Mattson Technology (MTSN) 10-K 11 Mar 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Mar. 04, 2016	Jun. 28, 2015
Document and Entity Information
Entity Registrant Name	MATTSON TECHNOLOGY INC
Entity Central Index Key	928,421
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		75,602,144
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 257,678,608

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Net revenue	$ 172,532	$ 178,404	$ 119,434
Cost of goods sold	107,785	119,587	82,028
Gross margin	64,747	58,817	37,406
Operating expenses:
Research, development and engineering	18,831	19,426	16,915
Selling, general and administrative	31,870	28,866	27,842
Restructuring and other charges	2,526	412	3,662
Total operating expenses	53,227	48,704	48,419
Income (loss) from operations	11,520	10,113	(11,013)
Interest income (expense), net	(135)	(228)	(494)
Other income (expense), net	(208)	335	(10)
Income (loss) before income taxes	11,177	10,220	(11,517)
Provision for (benefit from) income taxes	862	339	(542)
Net income (loss)	$ 10,315	$ 9,881	$ (10,975)
Net income (loss) per share:
Basic (in usd per share)	$ 0.14	$ 0.14	$ (0.19)
Diluted (in usd per share)	$ 0.13	$ 0.13	$ (0.19)
Shares used in computing net income (loss) per share:
Basic (in shares)	74,916	71,897	58,944
Diluted (in shares)	76,815	73,403	58,944

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 10,315	$ 9,881	$ (10,975)
Other comprehensive loss, net of tax
Changes in foreign currency translation adjustments	(1,882)	(2,659)	(148)
Change in unrealized investment loss	0	0	(29)
Other comprehensive loss	(1,882)	(2,659)	(177)
Comprehensive income (loss)	$ 8,433	$ 7,222	$ (11,152)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 33,427	$ 22,760
Accounts receivable, net of allowance for doubtful accounts of $672 as of December 31, 2015 and $669 as of December 31, 2014	21,685	33,578
Advance billings	1,639	4,653
Inventories	50,020	40,579
Prepaid expenses and other current assets	6,057	9,767
Total current assets	112,828	111,337
Property and equipment, net	8,236	7,534
Restricted cash	1,811	1,993
Other assets	438	623
Total assets	123,313	121,487
Current liabilities:
Accounts payable	16,912	22,434
Accrued compensation and benefits	4,707	4,601
Deferred revenues, current	5,144	9,110
Other current liabilities	6,195	6,630
Total current liabilities	32,958	42,775
Deferred revenues, non-current	375	1,160
Other liabilities	2,456	2,442
Total liabilities	$ 35,789	$ 46,377
Commitments and contingencies (Note 7)
Stockholders' equity:
Preferred stock, 2,000 shares authorized; none issued and outstanding	$ 0	$ 0
Common stock, par value $0.001, 120,000 shares authorized; 79,853 shares issued and 75,443 shares outstanding as of December 31, 2015; 78,267 shares issued and 74,009 shares outstanding as of December 31, 2014	80	78
Additional paid-in capital	692,407	687,871
Accumulated other comprehensive income	16,289	18,171
Treasury stock, 4,410 shares as of December 31, 2015 and 4,258 shares as of December 31, 2014	(38,640)	(38,083)
Accumulated deficit	(582,612)	(592,927)
Total stockholders' equity	87,524	75,110
Total liabilities and stockholders' equity	$ 123,313	$ 121,487

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Allowance for Doubtful Accounts	$ 672	$ 669
Stockholders' equity:
Preferred stock, shares authorized (in shares)	2,000	2,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value per share (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	120,000	120,000
Common stock, shares issued (in shares)	79,853	78,267
Common stock, shares, outstanding (in shares)	75,443	74,009
Treasury stock, shares (in shares)	4,410	4,258

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Treasury Stock	Accumulated Deficit
Beginning balance, stockholders' equity at Dec. 31, 2012	$ 43,292	$ 63	$ 652,041	$ 21,007	$ (37,986)	$ (591,833)
Beginnng balance, stockholders' equity (in shares) at Dec. 31, 2012		62,908			(4,181)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(10,975)
Other comprehensive loss, net of tax	(177)			(177)
Shares issued under employee stock plan, net	445		445
Shares issued under employee stock plan, net (in shares)		413
Shares issued under employee stock purchase plan	131		131
Shares issued under employee stock purchase plan (in shares)		63
Stock-based compensation expense	1,433		1,433
Ending balance, stockholders' equity at Dec. 31, 2013	34,149	$ 63	654,050	20,830	$ (37,986)	(602,808)
Ending balance, stockholders' equity (in shares) at Dec. 31, 2013		63,384			(4,181)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	9,881
Other comprehensive loss, net of tax	(2,659)			(2,659)
Shares issued under employee stock plan, net	307	$ 1	403		$ (97)
Shares issued under employee stock plan, net (in shares)		718			(77)
Shares issued under employee stock purchase plan	181		181
Shares issued under employee stock purchase plan (in shares)		83
Shares issued in connection with public offering, net of offering costs	31,725	$ 14	31,711
Shares issued in connection with public offering, net of offering costs (in shares)		14,082
Stock-based compensation expense	1,526		1,526
Ending balance, stockholders' equity at Dec. 31, 2014	75,110	$ 78	687,871	18,171	$ (38,083)	(592,927)
Ending balance, stockholders' equity (in shares) at Dec. 31, 2014		78,267			(4,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	10,315					10,315
Other comprehensive loss, net of tax	(1,882)			(1,882)
Shares issued under employee stock plan, net	1,384	$ 2	1,939		$ (557)
Shares issued under employee stock plan, net (in shares)		1,479			(152)
Shares issued under employee stock purchase plan	317		317
Shares issued under employee stock purchase plan (in shares)		107
Stock-based compensation expense	2,280		2,280
Ending balance, stockholders' equity at Dec. 31, 2015	$ 87,524	$ 80	$ 692,407	$ 16,289	$ (38,640)	$ (582,612)
Ending balance, stockholders' equity (in shares) at Dec. 31, 2015		79,853			(4,410)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ 10,315	$ 9,881	$ (10,975)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	2,927	2,805	3,971
Stock-based compensation	2,280	1,526	1,433
Deferred income taxes	163	145	(450)
Other non-cash items	(86)	59	(156)
Changes in assets and liabilities:
Accounts receivable	11,805	(7,332)	(10,702)
Advance billings	3,014	(1,307)	(1,626)
Inventories	(12,939)	(7,519)	(5,317)
Prepaid expenses and other current assets	3,179	(4,878)	(536)
Other assets	250	34	85
Accounts payable	(5,292)	(3,979)	14,687
Accrued compensation and benefits and other current liabilities	(395)	4,149	(4,554)
Deferred revenue	(4,744)	(808)	1,830
Other liabilities	264	(434)	(526)
Net cash provided by (used in) operating activities	10,741	(7,658)	(12,836)
Cash flows from investing activities:
(Increase) decrease in restricted cash	167	69	(202)
Purchases of property and equipment	(1,357)	(1,395)	(1,171)
Proceeds from sales of property and equipment	0	12	0
Net cash used in investing activities	(1,190)	(1,314)	(1,373)
Cash flows from financing activities:
Proceeds from revolving credit facility, net of borrowing costs	0	0	28,611
Repayment of revolving credit facility	0	(14,000)	(15,000)
Proceeds from issuance of common stock, net	1,701	32,213	576
Net cash provided by financing activities	1,701	18,213	14,187
Effect of exchange rate changes on cash and cash equivalents	(585)	(1,059)	246
Net increase in cash and cash equivalents	10,667	8,182	224
Cash and cash equivalents, beginning of period	22,760	14,578	14,354
Cash and cash equivalents, end of period	33,427	22,760	14,578
Supplemental Disclosure:
Cash paid for interest	94	210	578
Cash paid for income taxes, net of refunds	$ 419	$ 107	$ 422

BASIS OF PRESENTATION AND SIGNI

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES Nature of Operations Mattson Technology, Inc. (referred to in this Annual Report on Form 10-K as "Mattson," "we," "us," or "our") was incorporated in California in 1988 and reincorporated in Delaware in 1997. We design, manufacture, market and globally support semiconductor wafer processing equipment used in the fabrication of integrated circuits. Basis of Presentation The consolidated financial statements include the accounts of Mattson and all our subsidiaries. All inter-company balances and transactions have been eliminated. Our fiscal year ends on December 31. Our interim fiscal quarters are based upon the first quarter ending on the Sunday closest to March 31, with the second and third fiscal quarters each being exactly 13 weeks long. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("U.S. GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reported periods. We evaluate our estimates on an ongoing basis, including those related to the useful lives and fair value of long-lived assets, measurement of warranty obligations, valuation allowances for deferred tax assets, the fair value of stock-based compensation, estimates for allowance for doubtful accounts, and valuation of excess and obsolete inventories. Our estimates and assumptions can be subjective and complex and, consequently, actual results could differ materially from those estimates. Reclassifications For presentation purposes, certain prior period amounts have been reclassified to conform to the reporting in the current period financial statements. These reclassifications do not affect our net income, cash flows or stockholders' equity. Cash and Cash Equivalents We consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Our cash and cash equivalents are carried at fair market value, and consist primarily of cash balances and high-grade money market funds. Concentration of Credit Risk We maintain our cash and cash equivalents with several financial institutions. Deposits held with banks may exceed the amount of insurance provided by the Federal Deposit Insurance Corporation on such deposits. Generally these deposits may be redeemed upon demand and are maintained with financial institutions with reputable credit. We may invest in a variety of financial instruments, such as U.S. treasury bills and notes, commercial paper, money market funds and corporate bonds. We limit the amount of credit exposure to any one financial institution or commercial issuer. Historically, we have not experienced significant losses on these investments. Our trade accounts receivable are concentrated with companies in the semiconductor industry and are derived from sales in the U.S., Asia and Europe. As of December 31, 2015, five customers accounted for 10 percent or more of our accounts receivable, with each representing approximately 36 percent, 12 percent , 12 percent , 11 percent and 10 percent of our total net accounts receivable, respectively. As of December 31, 2014, one customer accounted for 74 percent of our total net accounts receivable. Allowance for Doubtful Accounts We perform ongoing credit evaluations of our customers and record specific allowances for doubtful accounts when a customer is unable to meet its financial obligations, as in the case of bankruptcy filings or deteriorated financial position. We estimate the allowance for doubtful accounts for all other customers based on factors such as current trends, the length of time the receivables are past due and historical collection experience. We write-off a receivable when all rights, remedies and recourses against the account and its principals are exhausted and record a benefit when previously reserved accounts are collected. Fair Value Measurements of Assets and Liabilities We measure certain of our assets and liabilities at fair value, using observable market data. The authoritative guidance on fair value measurement defines fair value as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, and establishes a valuation hierarchy based on the level of independent objective evidence available regarding the value of assets or liabilities. The authoritative guidance also establishes three classes of assets or liabilities: Level 1 consisting of assets and liabilities for which there are quoted prices for identical instruments in active markets; Level 2 consisting of assets and liabilities for which observable inputs other than Level 1 inputs are used such as prices for similar assets or liabilities in active markets or for identical assets or liabilities in less active markets and model-derived valuations for which the variables are derived from or corroborated by observable market data; and Level 3 consisting of assets or liabilities for which there are unobservable inputs to the valuation methodology that are significant to the measurement of the fair value. The category within the valuation hierarchy is based on the lowest level of input that is significant to the fair value measurement. Inventories Inventories are stated at the lower of cost or market, with cost determined on a first-in, first-out basis, and include material, labor and manufacturing overhead costs. Finished goods are reported as inventories until title transfers to the customer. Under our terms of sale, title generally transfers when we complete physical transfer of the products to the freight carrier, unless other customer practices or terms and conditions prevail. All inter-company profits pertaining to the sales and purchases of inventory among our subsidiaries are eliminated from the consolidated financial statements. We assess the valuation of all inventories, including manufacturing raw materials, work-in-process, finished goods and spare parts, at the end of each reporting period. Although we attempt to forecast future inventory demand, given the competitive pressures and cyclical nature of the semiconductor industry, there may be significant unanticipated changes in demand or technological developments that could have a significant impact on the value of our inventories and reported operating results in future periods. The carrying value of our inventory is reduced for estimated excess and obsolescence, which is the difference between its cost and the estimated market value based upon assumptions about future demand. We evaluate the inventory carrying value for potential excess and obsolete inventory exposures by analyzing historical and anticipated demand. In addition, inventories are evaluated for potential obsolescence due to the effect of known and anticipated engineering change orders and new products. If actual demand were to be substantially lower than estimated, additional inventory adjustments for excess or obsolete inventory might be required, which could have a material adverse effect on our business, financial condition and results of operations. Inventory includes evaluation tools placed at customer sites as part of our marketing efforts. We typically amortize the cost of the evaluation tools over an estimated period of five years, taking into consideration the estimated cost to refurbish the tools and the estimated net realizable value of the tools. The amortization charges are reported as selling, general and administrative expenses. Amortization expense was $0.1 million , $0.4 million and $1.5 million for the years ended December 31, 2015, 2014 and 2013, respectively. Property and Equipment Property and equipment are stated at cost. Depreciation is computed using the straight-line method based upon the estimated useful lives of the assets, which range from three to seven years. Leasehold improvements are amortized using the straight-line method over the useful lives or the term of the related lease, whichever is shorter. Depreciation expense was $2.8 million , $2.2 million and $2.2 million for the years ended December 31, 2015, 2014 and 2013, respectively. When assets are retired or otherwise disposed of, the assets and the associated accumulated depreciation are removed from the accounts. Repair and maintenance costs are expensed as incurred. Long-Lived Assets We review our long-lived assets, including property and equipment and intangibles, for impairment whenever events or changes in circumstances indicate that the carrying amounts of these assets may not be recoverable. Recoverability is measured by a comparison of the assets' carrying amount to their expected future undiscounted net cash flows. If such assets are considered to be impaired, the impairment to be recognized is measured based on the amount by which the carrying amount of the asset exceeds its fair value. We had no impairment charges in 2015, 2014 and 2013. Warranty The warranty we offer on equipment sales is generally twelve months, except where previous customer agreements state otherwise. A provision for the estimated cost of warranty, based on historical costs, is recorded as a cost of goods sold when the revenue is recognized for the sale of the related equipment. Our warranty obligations require us to repair or replace defective products or parts during the warranty period at no cost to the customer. The actual system performance and/or field expense profiles may differ from historical experience, and in those cases we adjust our warranty reserves accordingly. Actual warranty reserves and settlements against reserves are highly dependent on our equipment volumes. Revenue Recognition We derive revenues from the following primary sources - equipment (tool or system) sales, spare part sales and service and maintenance contracts. In accordance with the authoritative guidance on revenue recognition, we recognize revenue on equipment sales as follows: 1) for equipment sales of existing products with new specifications and for sales of new products, revenue is recognized upon customer acceptance; 2) for equipment sales to existing customers with previously demonstrated equipment acceptance, or equipment sales to new customers purchasing equipment with established reliability, we recognize revenue on a multiple element approach in which revenue is recognized upon the delivery of the separate elements to the customer. The revenue we recognize on a delivered element is limited to the amount that is not contingent upon the delivery of additional items such as installation and customer acceptance, and upon transfer of title. For equipment sales we generally recognize revenue for 90 percent of the total invoice amount as revenue upon shipment while 100 percent of the equipment's cost is recognized upon shipment. The remaining portion, generally 10 percent of the total invoice amount, is contingent upon customer acceptance and is recognized once installation services are completed and final customer acceptance of the equipment is received. The revenue relating to the undelivered elements is deferred using the relative selling price method, which allocates revenue to each element using the estimated selling prices for the deliverables when vendor-specific objective evidence or third-party evidence is not available. We have determined that the fair value of installation services is substantially less than the 10 percent of the total invoice amount typically assigned to the installation element in our customer agreements. As such, since the amount collectible upon successful installation and customer acceptance exceeds the fair value of the installation services, we defer the amount collectible upon successful installation and customer acceptance. From time to time, we allow customers to evaluate equipment, with the customer maintaining the right to return the equipment at its discretion with limited or no penalty. For this type of arrangement, we do not recognize revenue until customer acceptance is received. For spare parts, we recognize revenue upon shipment. For service and maintenance contracts, we recognize revenue on a straight-line basis over the service period of the related contract or as services are performed. In all cases, revenue is only recognized when persuasive evidence of an arrangement exists, delivery has occurred, the price is fixed or determinable and collectability is reasonably assured. Accounts receivable for which revenue has not been recognized are classified as advance billings. Research, Development and Engineering Expenses Research, development and engineering expenses include the personnel-related costs and outside consulting expenses associated with the research, development and engineering of new products and enhancements to existing products, facility related costs and other corporate allocations. These costs are expensed as incurred. Restructuring We recognize expenses related to employee termination benefits when the benefit arrangement is communicated to the employee and no significant future services are required of the employee. If an employee is required to render service until a specific termination date, which goes beyond the legal requirement or contractual notice period, in order to receive the termination benefits, the fair value of the associated liability would be recognized ratably over the future service period. Severance costs are determined in accordance with local statutory requirements and our policies. We recognize the present value of facility lease termination obligations, net of estimated sublease income and other exit costs, when there are future lease payments with no future economic benefit. Sublease income is estimated based on current market rates for similar properties. If we are unable to sublease the facility on a timely basis or if we are forced to sublease the facility at lower rates due to changes in market conditions, we would adjust the restructuring liability accordingly. Stock-Based Compensation We measure the fair value of all stock-based awards, including stock options, restricted stock units, and purchase rights under our employee stock purchase plan, on the date of grant and recognize the related stock-based compensation expense on a straight-line basis over the requisite service period, which is generally the vesting period. We use the Black-Scholes option-pricing model to determine the fair value of certain of our stock-based awards. The determination of fair value using the Black-Scholes model is affected by our stock price as well as assumptions regarding a number of complex and subjective variables, which includes expected stock price volatility over the term of the awards, actual and projected employee exercise and cancellation behaviors, risk-free interest rates, and expected dividends. We estimate the expected life of options based on an analysis of our historical experience of employee exercise and post-vesting termination behavior considered in relation to the contractual life of the option; expected volatility is based on the historical volatility of our common stock; and the risk-free interest rate is equal to the U.S. Treasury rate with a maturity approximating the expected life of the option. We do not currently pay cash dividends on our common stock and do not anticipate doing so in the foreseeable future; accordingly, the expected dividend yield is zero. We estimate forfeiture rates on stock-based awards at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from those estimates. Such forfeiture estimates are based on historical experience. If the assumptions for estimating stock-based compensation expense change in future periods, the amount of future stock-based compensation may differ significantly from the amount that we recorded in the current and prior periods. Stock-based compensation expense for the years ended December 31, 2015, 2014 and 2013 was $2.3 million , $1.5 million and $1.4 million , respectively. We did not capitalize any stock-based compensation as inventory in the years ended December 31, 2015, 2014 and 2013 as such amounts were immaterial. Foreign Currency The functional currencies of our foreign subsidiaries are their local currencies. All assets and liabilities of these foreign operations are translated into the U.S. dollar using exchange rates in effect at the end of the period, and revenues and costs are translated using average exchange rates for the period. Gains or losses from translation of foreign operations where the local currencies are the functional currency are included as a component of accumulated other comprehensive income in the accompanying consolidated balance sheets. Foreign currency transaction gains and losses are recorded in other income (expense), net in the accompanying consolidated statements of operations. For the years ended December 31, 2015, 2014 and 2013, we recorded a $0.3 million net foreign currency transaction loss, a $0.3 million net foreign currency transaction gain and a $0.6 million net foreign currency transaction loss, respectively. At December 31, 2015 and 2014, the cumulative translation adjustment was $16.3 million and $18.2 million , respectively. Income Taxes We provide for income taxes in accordance with the authoritative guidance, which requires a liability-based approach in accounting for income taxes. Deferred income tax assets and liabilities are recorded based on the differences between the financial statement and tax bases of assets and liabilities using enacted tax rates. Valuation allowances are provided against deferred income tax assets, which are not likely to be realized. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate resolution. Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases , which requires recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This guidance will be effective for us in the first quarter of fiscal 2019, with early adoption permitted. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In November 2015, the FASB issued ASU No. 2015-17, Income Taxes: Balance Sheet Classification of Deferred Taxes . This amendment eliminates the requirement to bifurcate deferred taxes between current and non-current on the balance sheet and requires that deferred tax liabilities and assets be classified as non-current on the balance sheet. This guidance will be effective for us in the first quarter of fiscal 2018, with early adoption permitted. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs. Debt issuance costs are specified incremental costs, other than those paid to the lender, that are directly attributable to issuing a debt instrument (i.e., third party costs). Prior to the adoption of this standard, debt issuance costs were required to be presented in the balance sheet as a deferred charge (i.e., an asset). This presentation differed from the presentation for a debt discount, which is a direct adjustment to the carrying value of the debt (i.e., a contra liability). This new standard requires that all costs incurred to issue debt be presented in the balance sheet as a direct deduction from the carrying value of the debt. This guidance will be effective for us in the first quarter of fiscal 2016, with early adoption permitted. We do not expect the adoption of this accounting standard to have a material impact on our financial statements and footnote disclosures. In August 2015, the FASB issued ASU No. 2015-15, Interest – Imputation of Interest: Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements. ASU 2015-15 provides additional guidance to ASU 2015-03, which did not address presentation or subsequent measurement of debt issuance costs related to line of credit arrangements. ASU 2015-15 noted that the SEC staff would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line of credit arrangement, regardless of whether there are any outstanding borrowings on the line of credit arrangement. As of December 31, 2015, we continue to record our unamortized debt issuance costs in connection with our revolving credit facility as an asset. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The FASB issued ASU 2014-09 to clarify the principles for recognizing revenue and to develop a common revenue standard for GAAP and International Financial Reporting Standards. The standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes the most current revenue recognition guidance. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers: Deferral of the Effective Date , deferring the effective date of ASU 2014-09 by one year. This guidance will be effective for us in the first quarter of fiscal 2018, with early adoption permitted for annual periods beginning after December 15, 2016. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In July 2015, the FASB issued ASU No. 2015-11, Inventory: Simplifying the Measurement of Inventory . Under ASU 2015-11, we are required to measure inventory at the lower of cost and net realizable value. The new guidance clarifies that net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. This guidance is effective for us in the first quarter of fiscal 2017, with early adoption permitted. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements—Going Concern . The update provides U.S. GAAP guidance on management’s responsibility in evaluating whether there is substantial doubt about a company’s ability to continue as a going concern and about related footnote disclosures. For each reporting period, management will be required to evaluate whether there are conditions or events that raise substantial doubt about a company’s ability to continue as a going concern within one year from the date the financial statements are issued. This guidance is effective for us beginning with our annual financial statements for fiscal 2017. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures.

BALANCE SHEET DETAILS

BALANCE SHEET DETAILS	12 Months Ended
	Dec. 31, 2015
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Details	BALANCE SHEET DETAILS At December 31, 2015 and 2014, we had restricted cash of $1.8 million and $2.0 million , respectively, which is primarily related to secured standby letters of credit for our long-term leases. Accordingly, such amounts are classified as long term in the accompanying consolidated balance sheets. See Note 7. Commitments and Contingencies for additional details related to the standby letters of credit. Components of inventories as of December 31 are shown below (in thousands): 2015 2014 Inventories: Purchased parts and raw materials $ 33,624 $ 28,143 Work-in-process 12,793 10,832 Finished goods 3,603 1,604 $ 50,020 $ 40,579 Components of prepaid expenses and other current assets as of December 31 are shown below (in thousands): 2015 2014 Prepaid expenses and other current assets: Value-added tax $ 3,194 $ 4,184 Other current assets 2,863 5,583 $ 6,057 $ 9,767 Components of property and equipment as of December 31 are shown below (in thousands): 2015 2014 Property and equipment, net: Machinery and equipment $ 41,463 $ 40,777 Furniture and fixtures 8,531 9,079 Leasehold improvements 16,396 17,646 66,390 67,502 Less: accumulated depreciation (58,154 ) (59,968 ) $ 8,236 $ 7,534 Components of other current liabilities as of December 31 are shown below (in thousands): 2015 2014 Other current liabilities: Warranty $ 3,040 $ 2,803 Value-added tax 1,250 1,547 Accrued restructuring charge - current 8 366 Other 1,897 1,914 $ 6,195 $ 6,630

FAIR VALUE MEASUREMENT

FAIR VALUE MEASUREMENT	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurement	FAIR VALUE MEASUREMENT Our money market funds are classified within Level 1 of the fair value hierarchy, as these instruments are valued using quoted market prices. Specifically, we value our investments in money market securities and certificates of deposit on quoted market prices in active markets. As of December 31, 2015 and 2014, we had no assets or liabilities classified within Level 2 or Level 3 and there were no transfers of instruments between Level 1, Level 2 and Level 3 regarding fair value measurement. Cash and cash equivalents and restricted cash are carried at fair value. Accounts receivable and accounts payable are valued at their carrying amounts, which approximate fair value due to their short-term nature. Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets and liabilities measured at fair value on a recurring basis are shown in the table below by their corresponding balance sheet captions and consisted of the following types of instruments as of December 31 (in thousands): 2015 2014 Fair Value Measurements at Reporting Date Using Fair Value Measurements at Reporting Date Using (Level 1) Total (Level 1) Total Assets measured at fair value: Cash and cash equivalents: (1) Money market funds $ 15,011 $ 15,011 $ 7,007 $ 7,007 Restricted cash: Money market funds 1,808 1,808 1,806 1,806 Total assets measured at fair value $ 16,819 $ 16,819 $ 8,813 $ 8,813 (1) Excludes $18.4 million and $15.8 million in cash held in our bank accounts at December 31, 2015 and December 31, 2014, respectively.

BUSINESS COMBINATION

BUSINESS COMBINATION	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Business Combination	BUSINESS COMBINATION Agreement and Plan of Merger On December 1, 2015, Mattson entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Beijing E-town Dragon Semiconductor Industry Investment Center (Limited Partnership), a People's Republic of China ("PRC") limited partnership (“Parent”), providing for the merger of an indirect subsidiary of Parent (“Merger Sub”) with and into Mattson (the “Merger”), with Mattson surviving the Merger as a subsidiary of Parent (the “Surviving Corporation”). The Merger Agreement was unanimously approved by Mattson’s Board of Directors (the “Board”). Pursuant to the terms and subject to the conditions of the Merger Agreement, at the Effective Time of the Merger, each share of Mattson’s common stock, par value $0.001 per share (the “Company Common Stock”), outstanding immediately prior to the Effective Time will be cancelled and automatically converted into the right to receive $3.80 in cash, without interest (the “Merger Consideration”), excluding any shares owned by Mattson, Parent or Merger Sub or any of their respective wholly-owned subsidiaries (which will be cancelled) and any shares with respect to which appraisal rights have been properly exercised under Delaware law. Beijing E-Town International Investment & Development Co., Ltd., the parent company to Parent, has irrevocably and unconditionally guaranteed to the Company the due and punctual payment and performance of Parent’s and Merger Sub’s obligations under the Merger Agreement. At the Effective Time, each option to purchase shares of Company Common Stock (a “Company Option”) that is outstanding and either (i) vested as of the Effective Time or (ii) held by a non-employee member of the Board will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (a) the aggregate number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, by (b) the Merger Consideration, less the per share exercise price of such Company Option. At the Effective Time, each Company Option that is outstanding, unvested and held by an employee who continues employment with Parent or any of its subsidiaries (including the Surviving Corporation) after the Merger will either (i) conditioned upon receipt of an executed Award Surrender Agreement (included in the Merger Agreement) by the Company at least one business day prior to the Effective Time, be converted into the right to receive an amount in cash determined by multiplying (a) the aggregate number of shares of Company Common Stock represented by such Company Option immediately prior to the Effective Time by (b) the Merger Consideration, less the per share exercise price of such Company Option (the “Unvested Option Consideration”), or (ii) be assumed by the Surviving Corporation, on the same terms, conditions and vesting schedule applicable to such Company Option immediately prior to the Effective Time (an “Assumed Option”), except that (x) the number of shares of the Surviving Corporation’s common stock for which such Assumed Option will be exercisable will equal the product (rounded down to the next whole number, with no cash paid for any fractional share eliminated by such rounding) of the number of shares of Company Common Stock that were issuable upon exercise of such Company Option immediately prior to the Effective Time and the Exchange Ratio (as defined in the Merger Agreement) and (y) the per share exercise price for the shares of the Surviving Corporation’s common stock issuable upon exercise of such Assumed Option will equal the quotient (rounded up to the next whole cent) obtained by dividing the exercise price per share of such Company Option immediately prior to the Effective Time by the Exchange Ratio. The Unvested Option Consideration will be subject to the same vesting restrictions and continued service requirements applicable to such Company Option as are in effect immediately prior to the Effective Time, except that any portion of the Unvested Option Consideration remaining outstanding as of December 31, 2016 will fully accelerate in full and be paid as of such date. At the Effective Time, each Company restricted stock unit (a “Company RSU”) that is outstanding and either (i) vested as of the Effective Time or (ii) held by a non-employee member of the Board will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (a) the aggregate number of shares of Company Common Stock subject to such Company RSU immediately prior to the Effective Time by (b) the Merger Consideration. At the Effective Time, all other outstanding Company RSUs not described in the immediately preceding sentence will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (x) the aggregate number of shares of Company Common Stock subject to such Company RSU immediately prior to the Effective Time by (y) the Merger Consideration (the “Unvested RSU Consideration”). The Unvested RSU Consideration will be subject to the same vesting restrictions and continued service requirements applicable to such Company RSU immediately prior to the Effective Time. The closing of the Merger is subject to the adoption of the Merger Agreement by the affirmative vote of holders of a majority of the outstanding shares of the Company Common Stock (the “Company Stockholder Approval”). The obligations of the parties to consummate the Merger are also subject to the satisfaction (or waiver, if applicable) of various customary conditions, including (i) the expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, (ii) filings and approvals with or by certain governmental authorities, including governmental authorities in the PRC and Taiwan, (iii) the absence of certain governmental orders prohibiting the Merger, (iv) the accuracy of the representations and warranties of each party contained in the Merger Agreement (subject to certain materiality qualifications) and (v) each party’s compliance with or performance of the covenants and agreements in the Merger Agreement in all material respects. The Company has made customary representations, warranties and covenants in the Merger Agreement, including, among others, covenants (i) to conduct its business in all material respects in the ordinary course consistent with past practices during the period between the execution of the Merger Agreement and the closing of the Merger, (ii) not to engage in specified types of transactions or take certain actions during the interim period unless consented to in writing by Parent, (iii) to convene and hold a meeting of its stockholders for the purpose of obtaining the Company Stockholder Approval and (iv) subject to certain exceptions, not to withdraw (or qualify or modify in a manner adverse to Parent) the recommendation of the Board that the Company’s stockholders adopt the Merger Agreement. The Company is also subject to customary restrictions on its ability to solicit alternative acquisition proposals from third parties and to provide non-public information to, and participate in discussions and engage in negotiations with, third parties regarding alternative acquisition proposals, with customary exceptions for alternative acquisition proposals that the Board determines either constitutes or could reasonably be expected to lead to a Superior Proposal (as defined in the Merger Agreement). Parent also has agreed to various covenants in the Merger Agreement, including, among others, covenants to take actions that may be necessary in order to obtain approval of the Merger with certain governmental authorities, subject to certain exceptions. The Merger Agreement contains certain termination rights for the Company and Parent. Upon termination of the Merger Agreement under specified circumstances, including in connection with the Company’s entry into a definitive agreement providing for the consummation of a Superior Proposal as permitted under the Merger Agreement, the Company will be required to pay Parent a termination fee of approximately $8.6 million . The Merger Agreement also provides that, upon termination of the Merger Agreement under specified circumstances, Parent will be required to pay the Company a termination fee of approximately $17.2 million (the “Parent Termination Fee”). The Parent Termination Fee will become payable from Parent to the Company if the Merger Agreement is terminated by the Company in the event that (i) Parent breaches its covenants such that the applicable closing condition regarding performance of covenants would not be satisfied or (ii) all of Parent’s conditions to closing are satisfied or waived and Parent has failed to consummate the Merger. Voting Agreement Concurrent with the execution of the Merger Agreement, the directors and certain executive officers of Mattson, in their capacities as holders of Company Common Stock or other equity interests of the Company, entered into a Voting Agreement with Parent (the “Voting Agreement”) pursuant to which each agreed, among other things, to (i) vote their Company Common Stock for the approval of the Merger Agreement and against any alternative proposal, and (ii) comply with certain restrictions on the disposition of their Company Common Stock, subject to the terms and conditions contained in the Voting Agreement. Each stockholder party to the Voting Agreement has granted an irrevocable proxy in favor of Parent to vote his or her shares or other equity interests as required by the terms of the Voting Agreement. The Voting Agreement will terminate upon the earlier of (a) the Effective Time, (b) the termination of the Voting Agreement by Parent, (c) the termination of the Merger Agreement in accordance with its terms or (d) a material modification, waiver or amendment of the Merger Agreement that (x) reduces the amount or changes the form of consideration to be paid to such stockholder party or (y) creates any additional conditions to the consummation of the Merger (unless such stockholder consents to such modification, waiver or amendment).

REVOLVING CREDIT FACLITY (Notes

REVOLVING CREDIT FACLITY (Notes)	12 Months Ended
	Dec. 31, 2015
Revolving Credit Facility [Abstract]
Revolving Credit Facility	REVOLVING CREDIT FACILITY On April 12, 2013, we entered into a three -year $25.0 million senior secured revolving credit facility ("credit facility") with Silicon Valley Bank. On October 21, 2014, we entered into Amendment Agreement No. 4 with Silicon Valley Bank ("Amendment"), which extends the term of our credit facility to October 12, 2017 . In the absence of an event of default, any amounts outstanding under the credit facility may be repaid and re-borrowed anytime until the termination date. This Amendment also allows us to make a one-time request to increase the existing credit facility up to an additional $25.0 million . The Amendment also retroactively lowered our required minimum consolidated earnings before interest, tax, depreciation, and amortization ("EBITDA") from $6.0 million to $2.0 million for the two consecutive quarters immediately prior to the end of the reporting period, commencing with the fiscal quarter ended September 28, 2014; established a minimum quick ratio requirement equal to or greater than 1.00 through March 29, 2015 and 1.25 thereafter; and removed certain financial covenants when our "Available Funds," as defined in the Amendment to be cash, cash equivalents and availability under the credit agreement, are equal to or greater than $30.0 million as of the last day of such fiscal quarter. Under the Amendment, the advances available to us under the borrowing base formula increased to 85 percent of eligible accounts receivable and advance billings and 50 percent of eligible inventory. At our option, the borrowings under the credit facility can bear interest at an Alternate Base Rate (“ABR”) or Eurodollar Rate. ABR loans bear interest at a per annum rate equal to the greater of the Federal Funds Effective Rate plus 0.5 percent or the prime rate, plus an applicable margin. Eurodollar loans bear interest at a margin over British Bankers' Association LIBOR Rate divided by 1 minus Eurocurrency Reserve Requirements. The Amendment lowered the applicable margin, as defined in the Amendment, with respect to our interest rate on outstanding borrowings to zero percent for ABR loans and 2.75 percent per annum for Eurodollar loans. As of December 31, 2015, the effective interest rate on any outstanding borrowings would have been 3.50 percent per annum, which is variable and represents the greater of the Federal Funds Effective Rate plus 0.50 percent or the prime rate. If an event of default occurs under the credit facility, the interest rate will increase by 2.0 percent per annum. The obligations under the credit facility are guaranteed by Mattson International, Inc., our wholly-owned subsidiary (together with Mattson, collectively referred to as the “Loan Parties”), and are secured by substantially all of the assets of the Loan Parties, including a pledge of the capital stock holdings of the Loan Parties in certain of our direct subsidiaries. The credit facility contains customary affirmative covenants and negative covenants including financial covenants requiring us and our subsidiaries to maintain a minimum level of consolidated EBITDA, for two consecutive quarters, and a minimum quick ratio, as well as restrictions on liens, investments, indebtedness, fundamental changes, sale leaseback transactions, swap agreements, accounting changes, dispositions of property, making certain restricted payments (including restrictions on dividends and stock repurchases), entering into new lines of business, and transactions with affiliates. Additionally, our credit facility restricts our ability to pay dividends, subject to certain limited exceptions. The obligations under the credit facility may be accelerated upon the occurrence of an event of default under the credit facility, which includes customary events of default, including payment defaults, defaults in the performance of affirmative and negative covenants, the material inaccuracy of representations or warranties, bankruptcy and insolvency related defaults, defaults relating to matters such as ERISA, judgments, and a change of control. Due to the potential for acceleration of obligations under the credit facility upon the occurrence of certain events, some of which are outside our control, borrowings under the credit facility are classified within current liabilities in the consolidated balance sheets. We incurred $0.4 million in debt issuance costs in connection with the credit facility and a commitment fee of $62,500 related to the extension of the term of the facility from April 12, 2016 to October 12, 2017. These costs are being amortized over the term of the credit facility. In addition, we pay monthly commitment fees equal to 0.375 percent per annum on the unused portion of the credit facility. At December 31, 2015 and 2014, we had no outstanding borrowings under the credit facility.

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	12 Months Ended
	Dec. 31, 2015
Restructuring Charges [Abstract]
Restructuring Charges	RESTRUCTURING CHARGES In December 2011, our management approved and initiated a cost reduction plan ("2011 Restructuring Plan") as part of a broad-based cost reduction initiative. The 2011 Restructuring Plan included the consolidation of our manufacturing and research and development facilities, including contract termination costs related to two vacant facilities; moving a portion of our outsourced spare parts logistics operations in-house; and workforce reductions. The following table summarizes changes in our restructuring accrual for the years ended December 31, 2015, 2014 and 2013 (in thousands): Employee Contract Other Total Balance at December 31, 2012 $ 2,005 $ 1,600 $ — $ 3,605 Restructuring charges 2,413 825 424 3,662 Payments (4,406 ) (1,322 ) (399 ) (6,127 ) Reserve adjustments (12 ) — (25 ) (37 ) Balance at December 31, 2013 — 1,103 — 1,103 Restructuring charges 506 (94 ) — 412 Payments (358 ) (739 ) — (1,097 ) Reserve adjustments (20 ) (32 ) — (52 ) Balance at December 31, 2014 128 238 — 366 Restructuring charges — — — — Payments (123 ) (205 ) — (328 ) Reserve adjustments (5 ) (25 ) — (30 ) Balance at December 31, 2015 $ — $ 8 $ — $ 8 For the year ended December 31, 2015, we had no restructuring charges, and made scheduled payments of $0.3 million to settle these restructuring liabilities. During 2015, we also incurred $2.5 million in costs associated with the Merger Agreement with Parent, which was recorded as restructuring and other charges in our consolidated statement of operations for the year ended December 31, 2015, and for which the unpaid portions are reflected within our accounts payable and other current liabilities in our consolidated balance sheet at December 31, 2015. For the year ended December 31, 2014, we recorded restructuring charges of $0.4 million , which included $0.5 million related to workforce reductions and a $0.1 million benefit from a revised estimate of our future rent obligations for one of our vacant facilities. We paid $0.4 million in employee severance and $0.7 million in contract termination costs during 2014. For the year ended December 31, 2013, we recorded restructuring charges of $3.7 million , which included $2.8 million in employee severance and other costs relating primarily to recruiting costs for our new chief executive officer and severance expense for our former chief executive officer totaling approximately $0.6 million , and other workforce reductions. We also incurred $0.8 million in contract termination costs related to future rent obligations, net of sublease income, associated with two vacated leased facilities. We paid $4.8 million in employee severance and other costs and $1.3 million in contract termination costs during 2013. As of December 31, 2015, we had a minimal balance in accrued restructuring charges, which was classified within other current liabilities in our consolidated balance sheet. As of December 31, 2015, we also had approximately $2.5 million in accounts payable related to professional fees and deal-related costs associated with the Merger Agreement with Parent. As of December 31, 2014, we had $0.4 million in accrued restructuring charges, which was classified within other current liabilities in our consolidated balance sheet.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Warranty The warranty offered by us on our system sales is generally twelve months, except where previous customer agreements state otherwise, and excludes certain consumable maintenance items. A provision for the estimated cost of warranty, based on historical costs, is recorded as cost of sales when the revenue is recognized. Our warranty obligations require us to repair or replace defective products or parts during the warranty period at no cost to the customer. The actual system performance and/or field warranty expense profiles may differ from historical experience, and in those cases, we adjust our warranty accruals accordingly. The following table summarizes changes in our product warranty accrual for the years ended December 31 (in thousands): 2015 2014 2013 Beginning balance $ 2,803 $ 1,786 $ 1,691 Warranties issued in the period 3,021 2,783 2,031 Costs to service warranties (3,974 ) (3,059 ) (1,981 ) Warranty accrual adjustments 1,190 1,293 45 Ending balance $ 3,040 $ 2,803 $ 1,786 Operating Leases We hold various operating leases related to our worldwide facilities and equipment. Our minimum annual lease commitments with respect to our operating leases were as follows as of December 31, 2015 (in thousands): Year Ending December 31, Minimum Future Lease Payments 2016 $ 2,378 2017 2,288 2018 2,235 2019 2,272 2020 2,324 Thereafter 13,329 $ 24,826 Rent expense was $3.7 million , $4.1 million and $3.9 million in 2015, 2014 and 2013, respectively. We recorded sublease income related to our Exton, Pennsylvania and Vancouver, Canada facilities of $0.2 million , $0.2 million and $0.4 million for the years ended December 31, 2015, 2014 and 2013, respectively. During 2015, our leases in Exton, Pennsylvania and Vancouver, Canada expired and were not renewed. In 2005, we entered into a lease agreement for the building which serves as our corporate headquarters in Fremont, California. The lease is for a period of ten years, which commenced on May 31, 2007, and has an initial annual base rent cost of approximately $1.4 million , with annual increases of approximately 3.5 percent. We also are responsible for an additional minimum lease payment at the end of the lease term of approximately $1.5 million , subject to adjustment, under a restoration cost obligation provision, which is being recognized on a straight-line basis over the lease term. To secure this obligation, we provided the landlord a standby letter of credit of $1.5 million . On January 7, 2016, we entered into an amendment with the landlord, which extends the lease term through December 31, 2026. Under the terms of the amendment, the annual base rent was adjusted upwards to approximately $1.6 million during 2016, with annual increases of 3.0 percent through 2026. Guarantees Standby Letters of Credit In the ordinary course of business, our bank provides standby letters of credit or other guarantee instruments on our behalf to certain parties as required. The standby letters of credit are primarily secured by money market accounts, which are classified as restricted cash in the accompanying consolidated balance sheets. We have never recorded any liability in connection with these guarantee arrangements beyond what is required to appropriately account for the underlying transaction being guaranteed. We do not believe, based on historical experience and information currently available, that it is probable that any amounts will be required to be paid under such guarantee arrangements. As of December 31, 2015 , the maximum potential amount that we could be required to pay under our outstanding standby letters of credit was $1.7 million , which was secured by $1.8 million in money market fund accounts and recorded as restricted cash. Canadian Minister of Industries In connection with our acquisition of Vortek Industries, Ltd. ("Vortek") in 2004, we became party to an agreement between Vortek and the Canadian Minister of Industries (the "Minister") relating to an investment in Vortek by Technology Partnerships Canada. Under the agreement, as amended, we, or Vortek (renamed Mattson Technology, Canada, Inc. ("MTC")) agreed to various terms, including (i) payment by us of a royalty to the Minister of 1.4 percent of net revenues from certain Flash RTP products, up to a total of C$14.3 million (approximately $10.3 million based on the applicable exchange rate as of December 31, 2015 ), (ii) MTC maintaining a specified average workforce of employees in Canada, making certain investments and complying with certain manufacturing, each, through October 27, 2009, and (iii) certain other covenants concerning protection of intellectual property rights. Under the provisions of this agreement, if MTC is dissolved, files for bankruptcy or we, or MTC, do not materially satisfy the obligations pursuant to any material terms or conditions, the Minister could demand payment of liquidated damages in the amount of C$14.3 million less any royalties paid to the Minister. As of October 27, 2009, we were no longer subject to covenant (ii), as discussed above but are still subject to the remaining terms and conditions until the earlier of payment of royalty of C$14.3 million (approximately $10.3 million based on the applicable exchange rate as of December 31, 2015 ) or through December 31, 2020. We have recorded approximately C$0.6 million in cumulative royalty charges to date. The movement of our Canadian operations to Germany did not result in the dissolution of MTC. Indemnification Agreements We are a party to a variety of agreements, pursuant to which we may be obligated to indemnify other parties with respect to certain matters. Typically, these obligations arise in the context of contracts under which we may agree to hold other parties harmless against losses arising from a breach of representations or with respect to certain intellectual property, operations or tax-related matters. Our obligations under these agreements may be limited in terms of time and/or amount, and in some instances, we may have defenses to asserted claims and/or recourse against third parties for payments made. It is not possible to predict the maximum potential amount of future payments under these or similar agreements due to the conditional nature of our obligations and the unique facts and circumstances involved in each particular agreement. Historically, our payments under these agreements have not had a material effect on our financial position, results of operations or cash flows. We believe if we were to incur a loss in any of these matters, such loss would not have a material effect on our financial position, results of operations or cash flows. We indemnify our directors and certain employees as permitted by law, and have entered into indemnification agreements with our directors and certain senior officers. We have not recorded a liability associated with these indemnification agreements, as we historically have not incurred any material costs associated with such indemnification agreements. Costs associated with such indemnification agreements may be mitigated, in whole or only in part, by insurance coverage that we maintain. Government Agencies As an exporter, we must comply with various laws and regulations relating to the export of products and technology from the U.S. and other countries having jurisdiction over our operations. In the U.S. these laws include the International Traffic in Arms Regulations ("ITAR") administered by the State Department's Directorate of Defense Trade Controls, the Export Administration Regulations ("EAR") administered by the Bureau of Industry and Security ("BIS"), and trade sanctions against embargoed countries and destinations administered by the U.S. Department of Treasury, Office of Foreign Assets Control ("OFAC"). The EAR governs products, parts, technology and software which present military or weapons proliferation concerns, so-called "dual use" items, and ITAR governs military items listed on the United States Munitions List. Prior to shipping certain items, we must obtain an export license or verify that license exemptions are available. In addition, we must comply with certain requirements related to documentation, record keeping, plant visits and hiring of foreign nationals. As previously reported, in 2008 we self-disclosed to BIS certain inadvertent EAR violations. In April 2012, we entered into a settlement agreement with BIS that resolved in full all matters contained in our voluntary self-disclosure. Under the settlement, we agreed to a civil penalty of $0.9 million of which we paid $0.3 million in May 2012. Payment of the remaining $0.6 million was suspended for a one -year period ended April 30, 2013 and was waived given there were no violations during that period. Litigation Overview In the ordinary course of business, we are subject to claims and litigation, including claims that we infringe third party patents, trademarks and other intellectual property rights. Although we believe that it is unlikely that any current claims or actions will have a material adverse impact on our operating results or our financial position, given the uncertainty of litigation, we cannot be certain of this. The defense of claims or actions against us, even if without merit, could result in the expenditure of significant financial and managerial resources. We record a legal liability when we believe it is both probable that a liability has been incurred, and the amount can be reasonably estimated. We monitor developments in our legal matters that could affect the estimate we have previously accrued. Significant judgment is required to determine both probability and the estimated amount. Class Action Merger Litigation On December 14, 2015, a putative shareholder class action complaint was filed in the Court of Chancery of the State of Delaware against Mattson, Mattson’s Board of Directors, Beijing E-town Dragon Semiconductor Industry Investment Center (“Parent”), and Dragon Acquisition Sub, Inc. (“Merger Sub”), captioned Sally Mogle v. Mattson Technology, et al. , Case No. 11807 (Del. Ch.). On December 22, 2015, a second putative shareholder class action complaint was filed in the Court of Chancery of the State of Delaware against Mattson’s Board of Directors, Parent, and Merger Sub, captioned Philip Durgin v. Kannappan, et al. , Case No. 11837 (Del. Ch.). The complaints allege, among other things, that the Company’s directors breached their fiduciary duties by approving the Merger Agreement and that Parent and Merger Sub aided and abetted the alleged breaches of fiduciary duty. The complaints seek, among other things, either to enjoin the proposed transaction or to rescind it should it be consummated, as well as unspecified damages, including attorneys’ and experts’ fees. On January 12, 2016, a putative shareholder class action complaint was filed in the Superior Court of the State of California, Alameda County against Mattson, Mattson’s Board of Directors, Parent, and Merger Sub, captioned Mary Salinas v. Mattson Technology, et al. , Case No. RG16799807. The complaint alleges, among other things, that the Company’s directors breached their fiduciary duties by approving the Merger Agreement, and that Mattson, Parent, and Merger Sub aided and abetted the alleged breaches of fiduciary duty. The complaint seeks, among other things, to enjoin the stockholder vote on the proposed transaction and unspecified damages, including attorneys’ and experts’ fees. On February 11, 2016, the plaintiff filed an Amended Class Action Complaint alleging, among other things, that Mattson’s directors breached their fiduciary duties by approving the Merger Agreement and issuing an incomplete and misleading Preliminary Proxy Statement, and that Mattson, Parent and Merger Sub aided and abetted the alleged breaches of fiduciary duty. The complaint seeks, among other things, either to enjoin the proposed transaction or to rescind it should it be consummated, as well as unspecified damages, including attorneys’ and experts’ fees. On February 22, 2016, a second putative shareholder class action complaint was filed in the Superior Court of the State of California, Alameda County against Mattson, Mattson’s Board of Directors, Parent, and Merger Sub, captioned Darrell Brown v. Mattson Technology, et al. , Case No. RG16804802. The complaint alleges, among other things, that Mattson’s directors breached their fiduciary duties by approving the Merger Agreement and issuing an incomplete and misleading Preliminary Proxy Statement, and that Mattson, Parent, and Merger Sub aided and abetted the alleged breaches of fiduciary duty. The complaint seeks, among other things, either to enjoin the proposed transaction or to rescind it should it be consummated, as well as unspecified damages, including attorneys’ and experts’ fees. On February 18, 2016, a putative shareholder class action complaint was filed in the United States District Court for the Northern District of California against the Board, captioned Talbert v. Mattson Technology, et al. , No. 8:16-cv-00811-LHK. The complaint alleges, among other things, that Mattson and Mattson’s Board of Directors violated Sections 14(a) and 20(a) of the Securities Exchange Act of 1934 by making materially incomplete and misleading statements and/or omitting material information from the Preliminary Proxy Statement. The complaint seeks to enjoin the stockholder vote on the proposed transaction, unspecified damages, certain other equitable relief, and attorneys’ fees and costs. Mattson is reviewing the complaints and has not yet formally responded to them, but believes the plaintiffs’ allegations are without merit and intends to defend against them vigorously. However, litigation is inherently uncertain and there can be no assurance regarding the likelihood that Mattson’s defense of these actions will be successful. Additional complaints containing substantially similar allegations may be filed in the future. We are unable at this time to estimate the effect of these lawsuits on our financial position, results of operations or cash flows.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS' EQUITY Common Stock In February 2014, we completed a registered public offering of 14.1 million newly issued shares of our common stock. The common stock was issued at a price to the public of $2.45 per share. We received net proceeds of approximately $31.7 million from the offering after deducting approximately $2.8 million in underwriting discounts and offering expenses. Treasury Stock We report common stock repurchased as treasury stock in the accompanying consolidated balance sheets. Treasury stock as of December 31, 2015 and 2014 was 4.4 million and 4.3 million shares, respectively, at a total purchase price of $38.6 million and $38.1 million , respectively. Accumulated Other Comprehensive Income The activity in accumulated other comprehensive income ("AOCI") for the years ended December 31 is as follows (thousands): 2015 2014 2013 Foreign currency translation adjustments: Balance at beginning of period $ 18,171 $ 20,830 $ 20,978 Reclassification to earnings, net of tax impact — — (488 ) Change in currency translation adjustment, net of tax (1,882 ) (2,659 ) 340 Balance at end of period 16,289 18,171 20,830 Unrealized investment gain: Balance at beginning of period — — 29 Reclassification to earnings, net of tax — — (29 ) Balance at end of period — — — Accumulated other comprehensive income end of period $ 16,289 $ 18,171 $ 20,830 During the fourth quarter of fiscal year 2013, we recorded $0.5 million in other income (expense), net within our consolidated statement of operations related to the liquidation of our Japan and Italy subsidiaries and the release of the corresponding cumulative translation adjustment. Stockholder Rights Plan On July 28, 2005, we adopted a Stockholder Rights Plan ("the Rights Plan"), under which stockholders of record at the close of business on August 15, 2005 received one share purchase right ("Right") for each share of our common stock held on that date. The description and terms of the Rights are set forth in a Rights Agreement between us and Computershare Trust Company, N.A. (the “Rights Agent”), as successor to Mellon Investor Services, LLC, dated July 28, 2005 (as amended from time to time, the “Rights Agreement”). On May 5, 2015, we entered into Amendment No. 3 to Rights Agreement (the “Amendment”) to change the “Final Expiration Date” of the Rights Agreement from July 27, 2015 to May 5, 2015. As a result of the Amendment, effective as of the close of business on May 5, 2015, the Rights expired and were no longer outstanding and the Rights Agreement terminated by its terms.

EMPLOYEE STOCK PLANS

EMPLOYEE STOCK PLANS	12 Months Ended
	Dec. 31, 2015
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Employee Stock Plans	EMPLOYEE STOCK PLANS As of December 31, 2015, we had approximately 4.1 million shares available for future grant under our 2012 Equity Incentive Plan (the "2012 Plan"). On May 28, 2015, the stockholders approved an amendment to our 2012 Plan: (i) increasing the number of shares reserved for issuance under the 2012 Plan by an additional 2.5 million shares, bringing the total shares reserved thereunder, to 19.5 million shares; and (ii) removing the 1.75 share accounting ratio applicable to stock awards and restricted stock units. Stock Options Options to purchase common stock granted under the 2012 Plan generally have terms not exceeding seven years. Options to purchase stock under our equity incentive plans are granted at exercise prices that are at least 100 percent of the fair market value of our common stock on the date of grant. Generally, 25 percent of the options vest on the first anniversary of the vesting commencement date, and the remaining options vest 1/36 per month for the next 36 months thereafter. In December 2013, our Board of Directors approved the adoption of monthly vesting of stock options for employees with a minimum of one year of service. We granted 0.7 million , 0.7 million and 1.6 million stock options during 2015, 2014 and 2013, respectively, with an estimated total grant date fair value of $1.2 million , $0.9 million and $1.4 million , respectively. We settle employee stock option exercises with newly issued common shares. The following table summarizes the stock option activity under all of our equity incentive plans for the years ended December 31, 2015 and 2014: Number of Shares Weighted- Weighted Average Remaining Contractual Life Aggregate Intrinsic Value (thousands) (years) (thousands) Outstanding at December 31, 2013 4,993 $ 2.18 4.9 $ 5,281 Granted 746 2.42 Exercised (486 ) 1.03 Forfeited or expired (333 ) 7.01 Outstanding at December 31, 2014 4,920 $ 2.01 4.2 $ 7,513 Granted 716 3.37 Exercised (1,017 ) 1.91 Forfeited or expired (447 ) 4.16 Outstanding at December 31, 2015 4,172 $ 2.04 4.1 $ 6,254 Vested and expected to vest at December 31, 2015 3,928 $ 2.00 4.0 $ 6,059 Exercisable at December 31, 2015 2,785 $ 1.80 3.5 $ 4,818 The aggregate intrinsic value represents the pre-tax differences between the exercise price of stock options and the quoted market price of our stock on December 31, 2015 for all in-the-money stock options. The following table provides supplemental information pertaining to our stock options for the years ended December 31 (in thousands, except weighted-average fair values): 2015 2014 2013 Weighted-average fair value of options granted $ 1.70 $ 1.24 $ 0.87 Intrinsic value of options exercised $ 2,449 $ 685 $ 386 Cash received from options exercised $ 1,940 $ 502 $ 445 Restricted Stock Units The 2012 Plan provides for grants of time-based and performance-based restricted stock units ("RSUs"). As of December 31, 2015 , we only had time-based RSUs outstanding. Historically, 25 percent of the time-based RSUs vest on each anniversary of the vesting commencement date or date of grant. In December 2013, our Board of Directors approved a quarterly vesting schedule for RSUs. On occasion, we grant time-based RSUs for varying purposes with different vesting schedules. Time-based RSUs granted under the 2012 Plan prior to May 28, 2015 are counted against the total number of shares of common stock available for grant at a ratio of 1.75 shares of common stock for every one share of common stock subject thereto, and RSUs granted on or after May 28, 2015 are counted against the total number of shares of common stock available for grant at a ratio of 1.00 share of common stock for every one share of common stock subject thereto. The following table summarizes RSU activity under all of our equity incentive plans for the years ended December 31, 2015 and 2014: Number of Shares Weighted Average Grant Date Fair Value (thousands) Outstanding at December 31, 2013 429 $ 1.45 Granted 697 2.42 Released (232 ) 1.99 Forfeited or Expired (17 ) 2.49 Outstanding at December 31, 2014 877 $ 2.06 Granted 994 3.33 Released (462 ) 2.57 Forfeited or Expired (120 ) 2.86 Outstanding at December 31, 2015 1,289 $ 2.78 Employee Stock Purchase Plan Our 1994 Employee Stock Purchase Plan (“1994 Plan”) was originally adopted by the Board of Directors and approved by the stockholders in 1994. In May 2014, the Board of Directors amended and restated the 1994 Plan, which was then approved by the stockholders, extending the term of the 1994 Plan by an additional ten years, with an expiration date of May 19, 2024 . Our 1994 Plan is a non-compensatory employee stock purchase plan ("ESPP"), which allows each eligible employee to withhold up to 15 percent of gross compensation over semi-annual six month ESPP periods to purchase shares of our common stock, limited to 2,000 shares per ESPP period through December 2013, and 4,000 shares per ESPP period thereafter. Under the ESPP, employees purchase stock at a price equal to 90 percent of the fair market value (generally the closing price of our common stock) on the last trading day prior to the end of the six month ESPP offering period. We reserved approximately 6.2 million shares of common stock for issuance under the ESPP, of which 2.4 million shares were available for issuance as of December 31, 2015 . We issued approximately 0.1 million shares under the ESPP in each of the years ended December 31, 2015, 2014 and 2013, with average purchase prices of $2.99 , $2.17 and $2.09 , respectively. Employee Savings Plan We have an employee retirement and savings plan (the "ESP"), which qualifies under section 401(k) of the Internal Revenue Code. All full-time employees of eligible age (over 21 years old) can participate in the ESP and can contribute up to an amount allowed by the applicable Internal Revenue Service guidelines. At our discretion, we can make matching contributions to the ESP equal to a percentage of the participants' contributions. For the years ended December 31, 2015, 2014 and 2013, we recorded 401(k) match contributions in the amount of $0.2 million , $0.2 million and $0.1 million , respectively.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION We account for stock-based compensation in accordance with the applicable authoritative guidance, which requires the measurement of stock-based compensation on the date of grant based on the fair value of the award, and the recognition of the expense over the requisite service period for the employee. Compensation related to RSUs is the intrinsic value on the date of grant, which is the closing price of our common stock less the employee exercise price, if any. Compensation related to stock options is determined using a stock option valuation model. Valuation Assumptions We use the Black-Scholes valuation model to determine the fair value of stock options. The Black-Scholes model requires the input of highly subjective assumptions, which are summarized in the table below for the years ended December 31: 2015 2014 2013 Expected dividend yield — — — Expected stock price volatility 66% 67% 83% Risk-free interest rate 1.2% 1.3% 0.9% Expected life of options in years 4.0 4.0 4.4 We estimate the expected life of options based on an analysis of our historical experience of employee exercise and post-vesting termination behavior considered in relation to the contractual life of the option. Expected volatility is based on the historical volatility of our common stock. The risk-free interest rate is the rate on a U.S. Treasury Bill, with a maturity approximating the expected life of the option. We do not currently pay cash dividends on our common stock and do not anticipate doing so in the foreseeable future. Accordingly, the expected dividend yield is zero . Stock-based compensation expense on time-based RSUs is determined based on the fair value of our common stock on the date of grant of the RSU and recognized over the vesting period. Our stock-based compensation for the years ended December 31 was as follows (in thousands): 2015 2014 2013 Stock-based compensation by type of award: Stock options $ 1,018 $ 994 $ 1,289 Restricted stock units 1,227 484 124 Employee stock purchase plan 35 48 20 $ 2,280 $ 1,526 $ 1,433 Stock-based compensation by category of expense: Cost of goods sold $ 167 $ 40 $ 52 Research, development and engineering 253 181 254 Selling, general and administrative 1,860 1,305 1,127 $ 2,280 $ 1,526 $ 1,433 We did not capitalize any stock-based compensation as inventory in the years ended December 31, 2015, 2014 and 2013 , as such amounts were immaterial. As of December 31, 2015 , we had $1.3 million in unrecognized stock-based compensation expense, net of estimated forfeitures, related to stock options that will be recognized over a weighted-average period of 2.2 years. As of December 31, 2015 , we had $2.6 million in unrecognized stock-based compensation expense, net of estimated forfeitures, related to unvested RSUs that will be recognized over a weighted-average period of 2.5 years.

GEOGRAPHIC AND CUSTOMER CONCENT

GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION	12 Months Ended
	Dec. 31, 2015
Geographic and Customer Concentration Information [Abstract]
Geographic and Customer Concentration Information	GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION The authoritative guidance on segment reporting and disclosure defines an operating segment as a component of an enterprise for which separate financial information is available that is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. For the purposes of evaluating our reportable segments, our Chief Executive Officer is the chief operating decision maker. We have one operating segment in which we design, manufacture and market advanced fabrication equipment for the semiconductor manufacturing industry. As our business is completely focused on one industry segment, the design, manufacture and marketing of advanced fabrication equipment to the semiconductor manufacturing industry, management believes that we have one reportable segment. Our net sales and profits are generated from the sales of systems and services in this one segment. The following table summarizes net revenue by geographic areas based on the installation locations of the systems and the location of services rendered (in thousands, except percentages): For the Years Ended December 31, 2015 2014 2013 Amount Percent Amount Percent Amount Percent Net revenue: United States $ 25,061 15 $ 25,716 14 $ 12,350 10 Korea 73,798 43 87,585 49 22,173 19 Taiwan 17,537 10 32,304 18 50,782 43 China 29,209 17 17,369 10 20,250 17 Other Asia 19,560 11 6,869 4 8,740 7 Europe and others 7,367 4 8,561 5 5,139 4 $ 172,532 100 $ 178,404 100 $ 119,434 100 In 2015, two customers accounted for 10 percent or more of our total net revenues. Sales to these customers represented 54 percent and 11 percent of our total net revenues, respectively. In 2014, one customer accounted for 10 percent or more of our total net revenues. Sales to this customer represented 61 percent of our total net revenues. In 2013, two customers accounted for 10 percent or more of our total net revenues. Sales to these customers represented approximately 35 percent and 33 percent of our total net revenues, respectively. As of December 31, 2015 , five customers accounted for 10 percent or more of our total net accounts receivable, representing approximately 36 percent, 12 percent , 12 percent , 11 percent and 10 percent of our total net accounts receivable, respectively. As of December 31, 2014 , one customer accounted for 10 percent or more of our net accounts receivable representing approximately 74 percent of our total net accounts receivable. Geographical information relating to our property and equipment, net, as of December 31 was as follows (in thousands): 2015 2014 Property and equipment, net: United States $ 3,350 $ 4,140 Germany 4,712 3,185 Others 174 209 $ 8,236 $ 7,534

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The components of income (loss) before income taxes for the years ended December 31 are as follows (in thousands): 2015 2014 2013 Domestic income (loss) $ 8,104 $ 7,248 $ (21,743 ) Foreign income 3,073 2,972 10,226 Income (loss) before income taxes $ 11,177 $ 10,220 $ (11,517 ) The provision for (benefit from) income taxes for the years ended December 31 consists of the following (in thousands): 2015 2014 2013 Current: Federal $ — $ — $ (466 ) State 51 28 52 Foreign 667 160 (125 ) Total current 718 188 (539 ) Deferred: Federal — — — State — — — Foreign 144 151 (3 ) Total deferred 144 151 (3 ) Provisions for (benefit from) income taxes $ 862 $ 339 $ (542 ) The provision for (benefit from) income taxes reconciles to the amount computed by multiplying income (loss) before income taxes by the U.S. statutory rate of 35 percent as follows (in thousands): Years Ended December 31, 2015 2014 2013 Benefits at statutory rate $ 3,912 $ 3,577 $ (4,031 ) Deferred tax asset valuation allowance (3,705 ) (3,182 ) 5,256 Foreign earnings taxed at U.S. rates 208 403 1,966 Foreign earnings taxed at different rates (388 ) (540 ) (3,315 ) State taxes, net of Federal benefit 416 18 34 Nondeductible stock option expense 173 244 322 Uncertain tax position reserve release 41 (188 ) (579 ) Other 205 7 (195 ) Provision for (benefit from) income taxes $ 862 $ 339 $ (542 ) Deferred tax assets (liabilities) as of December 31 are comprised of the following (in thousands): 2015 2014 Net operating loss carryforwards $ 159,722 $ 161,422 Reserves not currently deductible 6,106 7,547 Tax credit carryforwards 849 849 Depreciation 5,073 6,006 Deferred revenue 1,749 1,186 Other 1,599 (161 ) Total deferred tax asset 175,098 176,849 Valuation allowance (173,081 ) (176,786 ) Net deferred tax asset 2,017 63 Deferred tax liability (2,291 ) (192 ) Net deferred tax asset (liability) $ (274 ) $ (129 ) The valuation allowance as of December 31, 2015 and 2014 is against all deferred tax assets for all jurisdictions except Korea. Our valuation allowance was determined in accordance with the applicable authoritative guidance, which requires an assessment of both positive and negative evidence when determining whether it is more likely than not that deferred assets are recoverable, with such assessment being required on a jurisdiction-by-jurisdiction basis. In assessing the need for a valuation allowance in the current year, management considered historical levels of income and losses, expectations and risks associated with estimates of future taxable income and ongoing prudent and feasible tax planning strategies. Factors considered in providing a valuation allowance include the lack of a significant history of consistent profits, the cyclical nature of the overall semiconductor market thereby negatively impacting our ability to sustain or grow revenues and earnings and the lack of carry-back capacity to realize these assets. Based on the absence of sufficient positive objective evidence, management is unable to assert that it is more likely than not that we will generate sufficient taxable income to realize these remaining net deferred assets. The amount of the deferred tax asset valuation allowance, however, could be reduced in future periods to the extent that future taxable income is realized. As of December 31, 2015, we had Federal and state net operating loss carryforwards of approximately $447.9 million and $113.0 million , respectively, which will begin expiring in 2018 for Federal and 2016 for state. We also have foreign net operating loss carryforwards in Canada and Germany of approximately $38.0 million and $29.2 million , respectively. Canada's net operating loss carryforwards begin expiring in 2026. The German net operating loss carryforward has an indefinite carryover life. Our net operating losses include those acquired as a result of our acquisitions of Vortek, STEAG Semiconductor Division, CFM and Concept Systems Design, Inc. ("Concept"). The Federal and state net operating losses acquired from the STEAG Semiconductor Division, CFM and Concept are also subject to change in control limitations as defined in Section 382 of the Internal Revenue Code. If certain substantial changes in our ownership occur, there would be an additional annual limitation on the amount of the net operating loss carryforwards that can be utilized. As of December 31, 2015, we had research credit carryforwards of approximately $2.7 million and $4.0 million for Federal and state income tax purposes, respectively. If not utilized, the Federal carryforward will expire in various amounts beginning in 2017. The California tax credit can be carried forward indefinitely. We provide U.S. income taxes on the earnings of foreign subsidiaries unless the subsidiaries' earnings are considered indefinitely reinvested outside the U.S. As of December 31, 2015, U.S. income taxes were not provided for on a cumulative total of $0.4 million of undistributed earnings for certain foreign subsidiaries. If these earnings were repatriated, we would be subject to additional U.S. income taxes (subject to an adjustment for foreign tax credits). It is not practical to determine the income tax liability that might be incurred if these earnings were to be repatriated. We intend to permanently reinvest all foreign unremitted earnings of foreign subsidiaries outside of the U.S., except for Germany, Korea and Canada. Our indefinitely reinvested non-U.S. earnings have been deployed in active business operations, and it is unlikely that we will repatriate any portion of our indefinitely reinvested non-U.S. earnings in the future. As of December 31, 2015, our total unrecognized tax benefits were approximately $24.3 million exclusive of interest and penalties described below. Included in the $24.3 million is approximately $0.2 million of unrecognized tax benefits (net of Federal benefit), that if recognized, would favorably affect the effective tax rate in a future period before consideration of changes in the valuation allowance. We anticipate there will be no significant decrease in our unrecognized tax benefits within the next twelve months. Our practice is to recognize interest and/or penalties related to unrecognized tax benefits in income tax expense. Provisions for income taxes included estimated interest of zero , $0.1 million and $0.1 million for each of the years ended December 31, 2015, 2014 and 2013, respectively. As of December 31, 2015 and 2014, we had $0.1 million and $0.1 million , respectively, accrued for estimated interest. We had no accruals for estimated penalties as of December 31, 2015 and 2014. We are subject to United States Federal income tax as well as to income taxes in Germany, Korea and various other foreign and U.S. state jurisdictions. Our Federal and state income tax returns are generally not subject to examination by tax authorities for years before 2012 and 2011, respectively. However, due to the fact that we have net operating losses and credits carried forward, certain items attributable to technically closed years are still subject to adjustment by the relevant taxing authority through an adjustment to the tax attributes carried forward to open years. Our German and Korea income tax returns are generally not subject to examination by tax authorities before 2010. We had no material tax audits in progress as of December 31, 2015. A reconciliation of unrecognized tax benefits is as follows (in thousands): Years Ended December 31, 2015 2014 2013 Balance at the beginning of the year $ 25,100 $ 25,500 $ 25,900 Tax positions related to current and prior years: Additions — — 1,000 Reductions — (100 ) (100 ) Expiration of statutes of limitations (800 ) (300 ) (1,300 ) Balance at the end of the year $ 24,300 $ 25,100 $ 25,500

NET INCOME (LOSS) PER SHARE

NET INCOME (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	NET INCOME (LOSS) PER SHARE We present both basic and diluted net income (loss) per share on the face of our consolidated statements of operations in accordance with the authoritative guidance on earnings per share. Basic net income (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares of common stock outstanding for the period. Diluted net income (loss) per share is computed using the weighted-average number of shares of common stock outstanding plus the effect of common stock equivalents, unless the common stock equivalents are anti-dilutive. The potential dilutive shares of our common stock are determined using the treasury stock method. Under the treasury stock method, the amount the employee must pay for exercising stock options, the amount of compensation cost yet to be recognized for future service, and the amount of tax benefits that is to be recorded when the award becomes deductible are assumed be used to repurchase shares. The following table presents the computation of net income (loss) per share of common stock (in thousands, except for per share data): Years Ended December 31, 2015 2014 2013 Basic and diluted net income (loss) per share of common stock: Numerator: Net income (loss) $ 10,315 $ 9,881 $ (10,975 ) Denominator: Weighted-average shares outstanding - basic 74,916 71,897 58,944 Effect of dilutive stock options and restricted stock units 1,899 1,506 — Weighted-average shares outstanding - diluted 76,815 73,403 58,944 Net income (loss) per share of common stock: Basic $ 0.14 $ 0.14 $ (0.19 ) Diluted $ 0.13 $ 0.13 $ (0.19 ) For the years ended December 31, 2015 and 2014, options and RSUs totaling 1.2 million and 2.3 million , respectively, were excluded from diluted net income per share because their inclusion would have been anti-dilutive. Options are considered anti-dilutive if the exercise price exceeds the average stock price for the applicable period. For the year ended December 31, 2013, options to purchase our common stock and restricted stock units totaling 4.7 million were excluded from diluted net loss per share because their inclusion would have been anti-dilutive, since we had a net loss for the year ended December 31, 2013. Accordingly, basic and diluted net loss per share were the same for the year ended December 31, 2013.

SUPPLEMENTARY FINANCIAL INFORMA

SUPPLEMENTARY FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Supplementary Financial Information	Supplementary Financial Information Selected Quarterly Consolidated Financial Data (Unaudited) The following tables set forth our unaudited condensed consolidated statements of operations data for the eight quarterly periods ended December 31, 2015. We have prepared this unaudited information on a basis consistent with our audited consolidated financial statements, reflecting all normal recurring adjustments that we consider necessary for a fair presentation of our financial position and operating results for the fiscal quarters presented. Basic and diluted income (loss) per share is computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted income (loss) per share. The following tables set forth selected unaudited financial data for each quarter for the last two fiscal years (in thousands, except for per share amounts): Three Months Ended March 29, June 28, September 27, 2015 December 31, 2015 Net revenue $ 58,254 $ 43,334 $ 38,894 $ 32,049 Gross margin $ 21,394 $ 16,019 $ 13,547 $ 13,787 Income (loss) from operations $ 7,303 $ 2,677 $ 1,702 $ (162 ) Net income (loss) $ 6,305 $ 2,581 $ 2,023 $ (594 ) Net income (loss) per share: Basic $ 0.08 $ 0.03 $ 0.03 $ (0.01 ) Diluted $ 0.08 $ 0.03 $ 0.03 $ (0.01 ) Shares used in computing net income (loss) per share: Basic 74,700 74,920 75,129 75,287 Diluted 77,265 77,019 76,546 75,287 Three Months Ended March 30, June 29, September 28, 2014 December 31, 2014 Net revenue $ 43,198 $ 42,029 $ 38,430 $ 54,747 Gross margin $ 14,646 $ 13,296 $ 12,998 $ 17,877 Income from operations $ 2,701 $ 2,049 $ 546 $ 4,817 Net income $ 2,465 $ 1,916 $ 537 $ 4,963 Net income per share: Basic $ 0.04 $ 0.03 $ 0.01 $ 0.07 Diluted $ 0.04 $ 0.03 $ 0.01 $ 0.07 Shares used in computing net income per share: Basic 66,275 73,532 73,731 73,861 Diluted 67,971 74,679 75,023 75,486

SCHEDULE II - VALUATION AND QUA

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts - Allowance for Doubtful Accounts	SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (in thousands) Allowance for Doubtful Accounts Year Ended December 31, Balance at Beginning of Year Charged (Credited) to Income Deduction and Other Balance at End of Year 2015 $ 669 $ 3 $ — $ 672 2014 $ 704 $ — $ (35 ) $ 669 2013 $ 541 $ 163 $ — $ 704 Deferred Tax Asset Valuation Allowance Year Ended December 31, Balance at Beginning of Year Charged (Credited) to Income Deduction and Other Balance at End of Year 2015 $ 176,786 $ — $ (3,705 ) $ 173,081 2014 $ 181,499 $ — $ (4,713 ) $ 176,786 2013 $ 175,300 $ 6,199 $ — $ 181,499

BASIS OF PRESENTATION AND SIG23

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of Mattson and all our subsidiaries. All inter-company balances and transactions have been eliminated. Our fiscal year ends on December 31. Our interim fiscal quarters are based upon the first quarter ending on the Sunday closest to March 31, with the second and third fiscal quarters each being exactly 13 weeks long.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("U.S. GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reported periods. We evaluate our estimates on an ongoing basis, including those related to the useful lives and fair value of long-lived assets, measurement of warranty obligations, valuation allowances for deferred tax assets, the fair value of stock-based compensation, estimates for allowance for doubtful accounts, and valuation of excess and obsolete inventories. Our estimates and assumptions can be subjective and complex and, consequently, actual results could differ materially from those estimates.
Reclassifications	Reclassifications For presentation purposes, certain prior period amounts have been reclassified to conform to the reporting in the current period financial statements. These reclassifications do not affect our net income, cash flows or stockholders' equity.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Our cash and cash equivalents are carried at fair market value, and consist primarily of cash balances and high-grade money market funds.
Concentration of Credit Risk	Concentration of Credit Risk We maintain our cash and cash equivalents with several financial institutions. Deposits held with banks may exceed the amount of insurance provided by the Federal Deposit Insurance Corporation on such deposits. Generally these deposits may be redeemed upon demand and are maintained with financial institutions with reputable credit. We may invest in a variety of financial instruments, such as U.S. treasury bills and notes, commercial paper, money market funds and corporate bonds. We limit the amount of credit exposure to any one financial institution or commercial issuer. Historically, we have not experienced significant losses on these investments. Our trade accounts receivable are concentrated with companies in the semiconductor industry and are derived from sales in the U.S., Asia and Europe.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts We perform ongoing credit evaluations of our customers and record specific allowances for doubtful accounts when a customer is unable to meet its financial obligations, as in the case of bankruptcy filings or deteriorated financial position. We estimate the allowance for doubtful accounts for all other customers based on factors such as current trends, the length of time the receivables are past due and historical collection experience. We write-off a receivable when all rights, remedies and recourses against the account and its principals are exhausted and record a benefit when previously reserved accounts are collected.
Fair Value Measurements of Assets and Liabilities	Fair Value Measurements of Assets and Liabilities We measure certain of our assets and liabilities at fair value, using observable market data. The authoritative guidance on fair value measurement defines fair value as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, and establishes a valuation hierarchy based on the level of independent objective evidence available regarding the value of assets or liabilities. The authoritative guidance also establishes three classes of assets or liabilities: Level 1 consisting of assets and liabilities for which there are quoted prices for identical instruments in active markets; Level 2 consisting of assets and liabilities for which observable inputs other than Level 1 inputs are used such as prices for similar assets or liabilities in active markets or for identical assets or liabilities in less active markets and model-derived valuations for which the variables are derived from or corroborated by observable market data; and Level 3 consisting of assets or liabilities for which there are unobservable inputs to the valuation methodology that are significant to the measurement of the fair value. The category within the valuation hierarchy is based on the lowest level of input that is significant to the fair value measurement.
Inventory	Inventories Inventories are stated at the lower of cost or market, with cost determined on a first-in, first-out basis, and include material, labor and manufacturing overhead costs. Finished goods are reported as inventories until title transfers to the customer. Under our terms of sale, title generally transfers when we complete physical transfer of the products to the freight carrier, unless other customer practices or terms and conditions prevail. All inter-company profits pertaining to the sales and purchases of inventory among our subsidiaries are eliminated from the consolidated financial statements. We assess the valuation of all inventories, including manufacturing raw materials, work-in-process, finished goods and spare parts, at the end of each reporting period. Although we attempt to forecast future inventory demand, given the competitive pressures and cyclical nature of the semiconductor industry, there may be significant unanticipated changes in demand or technological developments that could have a significant impact on the value of our inventories and reported operating results in future periods. The carrying value of our inventory is reduced for estimated excess and obsolescence, which is the difference between its cost and the estimated market value based upon assumptions about future demand. We evaluate the inventory carrying value for potential excess and obsolete inventory exposures by analyzing historical and anticipated demand. In addition, inventories are evaluated for potential obsolescence due to the effect of known and anticipated engineering change orders and new products. If actual demand were to be substantially lower than estimated, additional inventory adjustments for excess or obsolete inventory might be required, which could have a material adverse effect on our business, financial condition and results of operations. Inventory includes evaluation tools placed at customer sites as part of our marketing efforts. We typically amortize the cost of the evaluation tools over an estimated period of five years, taking into consideration the estimated cost to refurbish the tools and the estimated net realizable value of the tools. The amortization charges are reported as selling, general and administrative expenses.
Property and Equipment	Property and Equipment Property and equipment are stated at cost. Depreciation is computed using the straight-line method based upon the estimated useful lives of the assets, which range from three to seven years. Leasehold improvements are amortized using the straight-line method over the useful lives or the term of the related lease, whichever is shorter. Depreciation expense was $2.8 million , $2.2 million and $2.2 million for the years ended December 31, 2015, 2014 and 2013, respectively. When assets are retired or otherwise disposed of, the assets and the associated accumulated depreciation are removed from the accounts. Repair and maintenance costs are expensed as incurred.
Long-Lived Assets	Long-Lived Assets We review our long-lived assets, including property and equipment and intangibles, for impairment whenever events or changes in circumstances indicate that the carrying amounts of these assets may not be recoverable. Recoverability is measured by a comparison of the assets' carrying amount to their expected future undiscounted net cash flows. If such assets are considered to be impaired, the impairment to be recognized is measured based on the amount by which the carrying amount of the asset exceeds its fair value.
Warranty	Warranty The warranty we offer on equipment sales is generally twelve months, except where previous customer agreements state otherwise. A provision for the estimated cost of warranty, based on historical costs, is recorded as a cost of goods sold when the revenue is recognized for the sale of the related equipment. Our warranty obligations require us to repair or replace defective products or parts during the warranty period at no cost to the customer. The actual system performance and/or field expense profiles may differ from historical experience, and in those cases we adjust our warranty reserves accordingly. Actual warranty reserves and settlements against reserves are highly dependent on our equipment volumes.
Revenue Recognition	Revenue Recognition We derive revenues from the following primary sources - equipment (tool or system) sales, spare part sales and service and maintenance contracts. In accordance with the authoritative guidance on revenue recognition, we recognize revenue on equipment sales as follows: 1) for equipment sales of existing products with new specifications and for sales of new products, revenue is recognized upon customer acceptance; 2) for equipment sales to existing customers with previously demonstrated equipment acceptance, or equipment sales to new customers purchasing equipment with established reliability, we recognize revenue on a multiple element approach in which revenue is recognized upon the delivery of the separate elements to the customer. The revenue we recognize on a delivered element is limited to the amount that is not contingent upon the delivery of additional items such as installation and customer acceptance, and upon transfer of title. For equipment sales we generally recognize revenue for 90 percent of the total invoice amount as revenue upon shipment while 100 percent of the equipment's cost is recognized upon shipment. The remaining portion, generally 10 percent of the total invoice amount, is contingent upon customer acceptance and is recognized once installation services are completed and final customer acceptance of the equipment is received. The revenue relating to the undelivered elements is deferred using the relative selling price method, which allocates revenue to each element using the estimated selling prices for the deliverables when vendor-specific objective evidence or third-party evidence is not available. We have determined that the fair value of installation services is substantially less than the 10 percent of the total invoice amount typically assigned to the installation element in our customer agreements. As such, since the amount collectible upon successful installation and customer acceptance exceeds the fair value of the installation services, we defer the amount collectible upon successful installation and customer acceptance. From time to time, we allow customers to evaluate equipment, with the customer maintaining the right to return the equipment at its discretion with limited or no penalty. For this type of arrangement, we do not recognize revenue until customer acceptance is received. For spare parts, we recognize revenue upon shipment. For service and maintenance contracts, we recognize revenue on a straight-line basis over the service period of the related contract or as services are performed. In all cases, revenue is only recognized when persuasive evidence of an arrangement exists, delivery has occurred, the price is fixed or determinable and collectability is reasonably assured. Accounts receivable for which revenue has not been recognized are classified as advance billings.
Research Development and Engineering Expenses	Research, Development and Engineering Expenses Research, development and engineering expenses include the personnel-related costs and outside consulting expenses associated with the research, development and engineering of new products and enhancements to existing products, facility related costs and other corporate allocations. These costs are expensed as incurred.
Restructuring	Restructuring We recognize expenses related to employee termination benefits when the benefit arrangement is communicated to the employee and no significant future services are required of the employee. If an employee is required to render service until a specific termination date, which goes beyond the legal requirement or contractual notice period, in order to receive the termination benefits, the fair value of the associated liability would be recognized ratably over the future service period. Severance costs are determined in accordance with local statutory requirements and our policies. We recognize the present value of facility lease termination obligations, net of estimated sublease income and other exit costs, when there are future lease payments with no future economic benefit. Sublease income is estimated based on current market rates for similar properties. If we are unable to sublease the facility on a timely basis or if we are forced to sublease the facility at lower rates due to changes in market conditions, we would adjust the restructuring liability accordingly.
Share-based Compensation	Stock-Based Compensation We measure the fair value of all stock-based awards, including stock options, restricted stock units, and purchase rights under our employee stock purchase plan, on the date of grant and recognize the related stock-based compensation expense on a straight-line basis over the requisite service period, which is generally the vesting period. We use the Black-Scholes option-pricing model to determine the fair value of certain of our stock-based awards. The determination of fair value using the Black-Scholes model is affected by our stock price as well as assumptions regarding a number of complex and subjective variables, which includes expected stock price volatility over the term of the awards, actual and projected employee exercise and cancellation behaviors, risk-free interest rates, and expected dividends. We estimate the expected life of options based on an analysis of our historical experience of employee exercise and post-vesting termination behavior considered in relation to the contractual life of the option; expected volatility is based on the historical volatility of our common stock; and the risk-free interest rate is equal to the U.S. Treasury rate with a maturity approximating the expected life of the option. We do not currently pay cash dividends on our common stock and do not anticipate doing so in the foreseeable future; accordingly, the expected dividend yield is zero. We estimate forfeiture rates on stock-based awards at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from those estimates. Such forfeiture estimates are based on historical experience. If the assumptions for estimating stock-based compensation expense change in future periods, the amount of future stock-based compensation may differ significantly from the amount that we recorded in the current and prior periods.
Foreign Currency	Foreign Currency The functional currencies of our foreign subsidiaries are their local currencies. All assets and liabilities of these foreign operations are translated into the U.S. dollar using exchange rates in effect at the end of the period, and revenues and costs are translated using average exchange rates for the period. Gains or losses from translation of foreign operations where the local currencies are the functional currency are included as a component of accumulated other comprehensive income in the accompanying consolidated balance sheets. Foreign currency transaction gains and losses are recorded in other income (expense), net in the accompanying consolidated statements of operations.
Income Tax	Income Taxes We provide for income taxes in accordance with the authoritative guidance, which requires a liability-based approach in accounting for income taxes. Deferred income tax assets and liabilities are recorded based on the differences between the financial statement and tax bases of assets and liabilities using enacted tax rates. Valuation allowances are provided against deferred income tax assets, which are not likely to be realized. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate resolution.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases , which requires recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This guidance will be effective for us in the first quarter of fiscal 2019, with early adoption permitted. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In November 2015, the FASB issued ASU No. 2015-17, Income Taxes: Balance Sheet Classification of Deferred Taxes . This amendment eliminates the requirement to bifurcate deferred taxes between current and non-current on the balance sheet and requires that deferred tax liabilities and assets be classified as non-current on the balance sheet. This guidance will be effective for us in the first quarter of fiscal 2018, with early adoption permitted. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs. Debt issuance costs are specified incremental costs, other than those paid to the lender, that are directly attributable to issuing a debt instrument (i.e., third party costs). Prior to the adoption of this standard, debt issuance costs were required to be presented in the balance sheet as a deferred charge (i.e., an asset). This presentation differed from the presentation for a debt discount, which is a direct adjustment to the carrying value of the debt (i.e., a contra liability). This new standard requires that all costs incurred to issue debt be presented in the balance sheet as a direct deduction from the carrying value of the debt. This guidance will be effective for us in the first quarter of fiscal 2016, with early adoption permitted. We do not expect the adoption of this accounting standard to have a material impact on our financial statements and footnote disclosures. In August 2015, the FASB issued ASU No. 2015-15, Interest – Imputation of Interest: Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements. ASU 2015-15 provides additional guidance to ASU 2015-03, which did not address presentation or subsequent measurement of debt issuance costs related to line of credit arrangements. ASU 2015-15 noted that the SEC staff would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line of credit arrangement, regardless of whether there are any outstanding borrowings on the line of credit arrangement. As of December 31, 2015, we continue to record our unamortized debt issuance costs in connection with our revolving credit facility as an asset. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The FASB issued ASU 2014-09 to clarify the principles for recognizing revenue and to develop a common revenue standard for GAAP and International Financial Reporting Standards. The standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes the most current revenue recognition guidance. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers: Deferral of the Effective Date , deferring the effective date of ASU 2014-09 by one year. This guidance will be effective for us in the first quarter of fiscal 2018, with early adoption permitted for annual periods beginning after December 15, 2016. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In July 2015, the FASB issued ASU No. 2015-11, Inventory: Simplifying the Measurement of Inventory . Under ASU 2015-11, we are required to measure inventory at the lower of cost and net realizable value. The new guidance clarifies that net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. This guidance is effective for us in the first quarter of fiscal 2017, with early adoption permitted. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements—Going Concern . The update provides U.S. GAAP guidance on management’s responsibility in evaluating whether there is substantial doubt about a company’s ability to continue as a going concern and about related footnote disclosures. For each reporting period, management will be required to evaluate whether there are conditions or events that raise substantial doubt about a company’s ability to continue as a going concern within one year from the date the financial statements are issued. This guidance is effective for us beginning with our annual financial statements for fiscal 2017. We are currently evaluating the impact that the implementation of this standard will have on our financial statements and footnote disclosures.

BALANCE SHEET DETAILS (Tables)

BALANCE SHEET DETAILS (Tables)	12 Months Ended
	Dec. 31, 2015
Balance Sheet Related Disclosures [Abstract]
Summary of Components of Inventories	Components of inventories as of December 31 are shown below (in thousands): 2015 2014 Inventories: Purchased parts and raw materials $ 33,624 $ 28,143 Work-in-process 12,793 10,832 Finished goods 3,603 1,604 $ 50,020 $ 40,579
Summary of Components of Prepaid Expense and Other Current Assets	Components of prepaid expenses and other current assets as of December 31 are shown below (in thousands): 2015 2014 Prepaid expenses and other current assets: Value-added tax $ 3,194 $ 4,184 Other current assets 2,863 5,583 $ 6,057 $ 9,767
Summary of Components of Property and Equipment	Components of property and equipment as of December 31 are shown below (in thousands): 2015 2014 Property and equipment, net: Machinery and equipment $ 41,463 $ 40,777 Furniture and fixtures 8,531 9,079 Leasehold improvements 16,396 17,646 66,390 67,502 Less: accumulated depreciation (58,154 ) (59,968 ) $ 8,236 $ 7,534
Summary of Components of Other Current Liabilities	Components of other current liabilities as of December 31 are shown below (in thousands): 2015 2014 Other current liabilities: Warranty $ 3,040 $ 2,803 Value-added tax 1,250 1,547 Accrued restructuring charge - current 8 366 Other 1,897 1,914 $ 6,195 $ 6,630

FAIR VALUE MEASUREMENT (Tables)

FAIR VALUE MEASUREMENT (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are shown in the table below by their corresponding balance sheet captions and consisted of the following types of instruments as of December 31 (in thousands): 2015 2014 Fair Value Measurements at Reporting Date Using Fair Value Measurements at Reporting Date Using (Level 1) Total (Level 1) Total Assets measured at fair value: Cash and cash equivalents: (1) Money market funds $ 15,011 $ 15,011 $ 7,007 $ 7,007 Restricted cash: Money market funds 1,808 1,808 1,806 1,806 Total assets measured at fair value $ 16,819 $ 16,819 $ 8,813 $ 8,813 (1) Excludes $18.4 million and $15.8 million in cash held in our bank accounts at December 31, 2015 and December 31, 2014, respectively.

RESTRUCTURING CHARGES (Tables)

RESTRUCTURING CHARGES (Tables)	12 Months Ended
	Dec. 31, 2015
Restructuring Charges [Abstract]
Summary of Changes in Restructuring Accrual	The following table summarizes changes in our restructuring accrual for the years ended December 31, 2015, 2014 and 2013 (in thousands): Employee Contract Other Total Balance at December 31, 2012 $ 2,005 $ 1,600 $ — $ 3,605 Restructuring charges 2,413 825 424 3,662 Payments (4,406 ) (1,322 ) (399 ) (6,127 ) Reserve adjustments (12 ) — (25 ) (37 ) Balance at December 31, 2013 — 1,103 — 1,103 Restructuring charges 506 (94 ) — 412 Payments (358 ) (739 ) — (1,097 ) Reserve adjustments (20 ) (32 ) — (52 ) Balance at December 31, 2014 128 238 — 366 Restructuring charges — — — — Payments (123 ) (205 ) — (328 ) Reserve adjustments (5 ) (25 ) — (30 ) Balance at December 31, 2015 $ — $ 8 $ — $ 8

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Summary of Changes in Product Warranty Accrual	The following table summarizes changes in our product warranty accrual for the years ended December 31 (in thousands): 2015 2014 2013 Beginning balance $ 2,803 $ 1,786 $ 1,691 Warranties issued in the period 3,021 2,783 2,031 Costs to service warranties (3,974 ) (3,059 ) (1,981 ) Warranty accrual adjustments 1,190 1,293 45 Ending balance $ 3,040 $ 2,803 $ 1,786
Schedule of Minimum Annual Lease Commitments with Respect to Operating Leases	We hold various operating leases related to our worldwide facilities and equipment. Our minimum annual lease commitments with respect to our operating leases were as follows as of December 31, 2015 (in thousands): Year Ending December 31, Minimum Future Lease Payments 2016 $ 2,378 2017 2,288 2018 2,235 2019 2,272 2020 2,324 Thereafter 13,329 $ 24,826

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Schedule of Activity in Accumulated Other Comprehensive Income	The activity in accumulated other comprehensive income ("AOCI") for the years ended December 31 is as follows (thousands): 2015 2014 2013 Foreign currency translation adjustments: Balance at beginning of period $ 18,171 $ 20,830 $ 20,978 Reclassification to earnings, net of tax impact — — (488 ) Change in currency translation adjustment, net of tax (1,882 ) (2,659 ) 340 Balance at end of period 16,289 18,171 20,830 Unrealized investment gain: Balance at beginning of period — — 29 Reclassification to earnings, net of tax — — (29 ) Balance at end of period — — — Accumulated other comprehensive income end of period $ 16,289 $ 18,171 $ 20,830

EMPLOYEE STOCK PLANS (Tables)

EMPLOYEE STOCK PLANS (Tables)	12 Months Ended
	Dec. 31, 2015
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Summary of Stock Option Activity	The following table summarizes the stock option activity under all of our equity incentive plans for the years ended December 31, 2015 and 2014: Number of Shares Weighted- Weighted Average Remaining Contractual Life Aggregate Intrinsic Value (thousands) (years) (thousands) Outstanding at December 31, 2013 4,993 $ 2.18 4.9 $ 5,281 Granted 746 2.42 Exercised (486 ) 1.03 Forfeited or expired (333 ) 7.01 Outstanding at December 31, 2014 4,920 $ 2.01 4.2 $ 7,513 Granted 716 3.37 Exercised (1,017 ) 1.91 Forfeited or expired (447 ) 4.16 Outstanding at December 31, 2015 4,172 $ 2.04 4.1 $ 6,254 Vested and expected to vest at December 31, 2015 3,928 $ 2.00 4.0 $ 6,059 Exercisable at December 31, 2015 2,785 $ 1.80 3.5 $ 4,818
Schedule of Supplemental Information Pertaining to Stock Options	The following table provides supplemental information pertaining to our stock options for the years ended December 31 (in thousands, except weighted-average fair values): 2015 2014 2013 Weighted-average fair value of options granted $ 1.70 $ 1.24 $ 0.87 Intrinsic value of options exercised $ 2,449 $ 685 $ 386 Cash received from options exercised $ 1,940 $ 502 $ 445
Summary of Restricted Stock Unit Activity	The following table summarizes RSU activity under all of our equity incentive plans for the years ended December 31, 2015 and 2014: Number of Shares Weighted Average Grant Date Fair Value (thousands) Outstanding at December 31, 2013 429 $ 1.45 Granted 697 2.42 Released (232 ) 1.99 Forfeited or Expired (17 ) 2.49 Outstanding at December 31, 2014 877 $ 2.06 Granted 994 3.33 Released (462 ) 2.57 Forfeited or Expired (120 ) 2.86 Outstanding at December 31, 2015 1,289 $ 2.78

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Black-Scholes Valuation Model used to Determine Fair Value of Stock Options	The Black-Scholes model requires the input of highly subjective assumptions, which are summarized in the table below for the years ended December 31: 2015 2014 2013 Expected dividend yield — — — Expected stock price volatility 66% 67% 83% Risk-free interest rate 1.2% 1.3% 0.9% Expected life of options in years 4.0 4.0 4.4
Schedule of Stock-based Compensation	Our stock-based compensation for the years ended December 31 was as follows (in thousands): 2015 2014 2013 Stock-based compensation by type of award: Stock options $ 1,018 $ 994 $ 1,289 Restricted stock units 1,227 484 124 Employee stock purchase plan 35 48 20 $ 2,280 $ 1,526 $ 1,433 Stock-based compensation by category of expense: Cost of goods sold $ 167 $ 40 $ 52 Research, development and engineering 253 181 254 Selling, general and administrative 1,860 1,305 1,127 $ 2,280 $ 1,526 $ 1,433

GEOGRAPHIC AND CUSTOMER CONCE31

GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2015
Geographic and Customer Concentration Information [Abstract]
Summary of Net Revenue by Geographic Areas Based on the Installation Locations of the Systems and the Location of Services Rendered	The following table summarizes net revenue by geographic areas based on the installation locations of the systems and the location of services rendered (in thousands, except percentages): For the Years Ended December 31, 2015 2014 2013 Amount Percent Amount Percent Amount Percent Net revenue: United States $ 25,061 15 $ 25,716 14 $ 12,350 10 Korea 73,798 43 87,585 49 22,173 19 Taiwan 17,537 10 32,304 18 50,782 43 China 29,209 17 17,369 10 20,250 17 Other Asia 19,560 11 6,869 4 8,740 7 Europe and others 7,367 4 8,561 5 5,139 4 $ 172,532 100 $ 178,404 100 $ 119,434 100
Summary of Geographic Information Relating to Property and Equipment, Net	Geographical information relating to our property and equipment, net, as of December 31 was as follows (in thousands): 2015 2014 Property and equipment, net: United States $ 3,350 $ 4,140 Germany 4,712 3,185 Others 174 209 $ 8,236 $ 7,534

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Components of Income (Loss) Before Income Taxes	The components of income (loss) before income taxes for the years ended December 31 are as follows (in thousands): 2015 2014 2013 Domestic income (loss) $ 8,104 $ 7,248 $ (21,743 ) Foreign income 3,073 2,972 10,226 Income (loss) before income taxes $ 11,177 $ 10,220 $ (11,517 )
Schedule of Provision for (Benefit from) Income Taxes	The provision for (benefit from) income taxes for the years ended December 31 consists of the following (in thousands): 2015 2014 2013 Current: Federal $ — $ — $ (466 ) State 51 28 52 Foreign 667 160 (125 ) Total current 718 188 (539 ) Deferred: Federal — — — State — — — Foreign 144 151 (3 ) Total deferred 144 151 (3 ) Provisions for (benefit from) income taxes $ 862 $ 339 $ (542 )
Schedule of Provision for (Benefit from) Income Taxes Reconciliation to Amount Computed by Multiplying Income (Loss) Before Income Taxes by the U.S. Statutory Rate	The provision for (benefit from) income taxes reconciles to the amount computed by multiplying income (loss) before income taxes by the U.S. statutory rate of 35 percent as follows (in thousands): Years Ended December 31, 2015 2014 2013 Benefits at statutory rate $ 3,912 $ 3,577 $ (4,031 ) Deferred tax asset valuation allowance (3,705 ) (3,182 ) 5,256 Foreign earnings taxed at U.S. rates 208 403 1,966 Foreign earnings taxed at different rates (388 ) (540 ) (3,315 ) State taxes, net of Federal benefit 416 18 34 Nondeductible stock option expense 173 244 322 Uncertain tax position reserve release 41 (188 ) (579 ) Other 205 7 (195 ) Provision for (benefit from) income taxes $ 862 $ 339 $ (542 )
Schedule of Deferred Tax Assets and Liabilities	Deferred tax assets (liabilities) as of December 31 are comprised of the following (in thousands): 2015 2014 Net operating loss carryforwards $ 159,722 $ 161,422 Reserves not currently deductible 6,106 7,547 Tax credit carryforwards 849 849 Depreciation 5,073 6,006 Deferred revenue 1,749 1,186 Other 1,599 (161 ) Total deferred tax asset 175,098 176,849 Valuation allowance (173,081 ) (176,786 ) Net deferred tax asset 2,017 63 Deferred tax liability (2,291 ) (192 ) Net deferred tax asset (liability) $ (274 ) $ (129 )
Schedule of Reconciliation of Unrecognized Tax Benefits	A reconciliation of unrecognized tax benefits is as follows (in thousands): Years Ended December 31, 2015 2014 2013 Balance at the beginning of the year $ 25,100 $ 25,500 $ 25,900 Tax positions related to current and prior years: Additions — — 1,000 Reductions — (100 ) (100 ) Expiration of statutes of limitations (800 ) (300 ) (1,300 ) Balance at the end of the year $ 24,300 $ 25,100 $ 25,500

NET INCOME (LOSS) PER SHARE (Ta

NET INCOME (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Computation of Net Income (Loss) per Share of Common Stock	The following table presents the computation of net income (loss) per share of common stock (in thousands, except for per share data): Years Ended December 31, 2015 2014 2013 Basic and diluted net income (loss) per share of common stock: Numerator: Net income (loss) $ 10,315 $ 9,881 $ (10,975 ) Denominator: Weighted-average shares outstanding - basic 74,916 71,897 58,944 Effect of dilutive stock options and restricted stock units 1,899 1,506 — Weighted-average shares outstanding - diluted 76,815 73,403 58,944 Net income (loss) per share of common stock: Basic $ 0.14 $ 0.14 $ (0.19 ) Diluted $ 0.13 $ 0.13 $ (0.19 )

SUPPLEMENTARY FINANCIAL INFOR34

SUPPLEMENTARY FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Unaudited Financial Data for Each Quarter	The following tables set forth selected unaudited financial data for each quarter for the last two fiscal years (in thousands, except for per share amounts): Three Months Ended March 29, June 28, September 27, 2015 December 31, 2015 Net revenue $ 58,254 $ 43,334 $ 38,894 $ 32,049 Gross margin $ 21,394 $ 16,019 $ 13,547 $ 13,787 Income (loss) from operations $ 7,303 $ 2,677 $ 1,702 $ (162 ) Net income (loss) $ 6,305 $ 2,581 $ 2,023 $ (594 ) Net income (loss) per share: Basic $ 0.08 $ 0.03 $ 0.03 $ (0.01 ) Diluted $ 0.08 $ 0.03 $ 0.03 $ (0.01 ) Shares used in computing net income (loss) per share: Basic 74,700 74,920 75,129 75,287 Diluted 77,265 77,019 76,546 75,287 Three Months Ended March 30, June 29, September 28, 2014 December 31, 2014 Net revenue $ 43,198 $ 42,029 $ 38,430 $ 54,747 Gross margin $ 14,646 $ 13,296 $ 12,998 $ 17,877 Income from operations $ 2,701 $ 2,049 $ 546 $ 4,817 Net income $ 2,465 $ 1,916 $ 537 $ 4,963 Net income per share: Basic $ 0.04 $ 0.03 $ 0.01 $ 0.07 Diluted $ 0.04 $ 0.03 $ 0.01 $ 0.07 Shares used in computing net income per share: Basic 66,275 73,532 73,731 73,861 Diluted 67,971 74,679 75,023 75,486

BASIS OF PRESENTATION AND SIG35

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2015USD ($)customer	Dec. 31, 2014USD ($)customer	Dec. 31, 2013USD ($)
Accounting Policies [Line Items]
Estimated period of amortization for the cost of inventory evaluation tools	5 years
Amortization expense	$ 100,000	$ 400,000	$ 1,500,000
Depreciation expense	2,800,000	2,200,000	2,200,000
Impairment charge related to property and equipment	$ 0	0	0
General length of product warranty	12 months
Expected dividend yield	0.00%
Stock-based compensation expense	$ 2,280,000	1,526,000	1,433,000
Net foreign currency transaction loss	(300,000)		$ (600,000)
Net foreign currency transaction gain		300,000
Cumulative translation adjustment	$ 16,300,000	$ 18,200,000
Minimum
Accounting Policies [Line Items]
Estimated useful lives of assets	3 years
Maximum
Accounting Policies [Line Items]
Estimated useful lives of assets	7 years
Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Number of major customers | customer	5	1
Net accounts receivable, major customer A | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	36.00%	74.00%
Net accounts receivable, major customer B | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	12.00%
Net accounts receivable, major customer C | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	12.00%
Net accounts receivable, major customer D | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	11.00%
Net accounts receivable, major customer E | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	10.00%
Equipment sales
Accounting Policies [Line Items]
Percent revenue recognized upon shipment	90.00%
Percent cost recognized upon shipment	100.00%
Percent revenue recognized upon customer acceptance	10.00%
Installation services
Accounting Policies [Line Items]
Percentage of total invoice amount typically assigned to the installation element in customer agreements	10.00%

BALANCE SHEET DETAILS - Narrati

BALANCE SHEET DETAILS - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Balance Sheet Related Disclosures [Abstract]
Restricted cash	$ 1,811	$ 1,993

BALANCE SHEET DETAILS - Summary

BALANCE SHEET DETAILS - Summary of Components of Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Inventories:
Purchased parts and raw materials	$ 33,624	$ 28,143
Work-in-process	12,793	10,832
Finished goods	3,603	1,604
Inventories, net	$ 50,020	$ 40,579

BALANCE SHEET DETAILS - Summa38

BALANCE SHEET DETAILS - Summary of Components of Prepaid Expense and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Prepaid expenses and other current assets:
Value-added tax	$ 3,194	$ 4,184
Other current assets	2,863	5,583
Prepaid expenses and other current assets	$ 6,057	$ 9,767

BALANCE SHEET DETAILS - Summa39

BALANCE SHEET DETAILS - Summary of Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, and equipment, gross	$ 66,390	$ 67,502
Less: accumulated depreciation	(58,154)	(59,968)
Property and equipment, net	8,236	7,534
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, and equipment, gross	41,463	40,777
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, and equipment, gross	8,531	9,079
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, and equipment, gross	$ 16,396	$ 17,646

BALANCE SHEET DETAILS - Summa40

BALANCE SHEET DETAILS - Summary of Components of Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Other current liabilities:
Warranty	$ 3,040	$ 2,803
Value-added tax	1,250	1,547
Accrued restructuring charge - current	8	366
Other	1,897	1,914
Other current liabilities	$ 6,195	$ 6,630

FAIR VALUE MEASUREMENT - Schedu

FAIR VALUE MEASUREMENT - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets measured at fair value:
Total assets measured at fair value	$ 16,819	$ 8,813
Money market funds
Assets measured at fair value:
Cash and cash equivalents	15,011	7,007
Restricted cash	1,808	1,806
Fair value measurements at reporting date, level 1
Assets measured at fair value:
Total assets measured at fair value	16,819	8,813
Fair value measurements at reporting date, level 1 | Money market funds
Assets measured at fair value:
Cash and cash equivalents	15,011	7,007
Restricted cash	$ 1,808	$ 1,806

FAIR VALUE MEASUREMENT - Sche42

FAIR VALUE MEASUREMENT - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Footnote) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash	$ 18.4	$ 15.8

BUSINESS COMBINATION - Narrativ

BUSINESS COMBINATION - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 01, 2015	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Common stock, par value per share (in usd per share)		$ 0.001	$ 0.001
Beijing E-Town Dragon Semiconductor Industry Investment Center
Business Acquisition [Line Items]
Common stock, par value per share (in usd per share)	$ 0.001
Conversion of stock outstanding (in usd per share)	$ 3.80
Termination fee	$ 8.6
Beijing E-Town Dragon Semiconductor Industry Investment Center | Parent
Business Acquisition [Line Items]
Termination fee	$ 17.2

REVOLVING CREDIT FACLITY - Narr

REVOLVING CREDIT FACLITY - Narrative (Details)	Mar. 30, 2015	Oct. 21, 2014USD ($)Quarter	Oct. 20, 2014USD ($)	Apr. 12, 2013USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Line of Credit Facility [Line Items]
Debt issuance costs				$ 400,000
Revolving credit facility
Line of Credit Facility [Line Items]
Revolving credit facility, term				3 years
Revolving credit facility, maximum borrowing capacity				$ 25,000,000
Effective interest rate					3.50%
Percentage monthly commitment fee on unused portion of credit facility				0.375%
Revolving credit facility, amount outstanding					$ 0	$ 0
Revolving credit facility | Alternative base rate | Federal funds effective rate
Line of Credit Facility [Line Items]
Variable rate				0.50%
Revolving credit facility | Alternative base rate | Prime rate
Line of Credit Facility [Line Items]
Interest rate increase in an event of default				2.00%
Revolving credit facility | Eurodollar rate
Line of Credit Facility [Line Items]
Denominator of applicable margin				1
Revolving credit facility | Amended agreement No. 4
Line of Credit Facility [Line Items]
Revolving credit facility, one time additional borrowing		$ 25,000,000
Revolving credit facility, minimum EBITDA		$ 2,000,000	$ 6,000,000
Number of consecutive quarters immediately prior to end of reporting period to determine minimum EBITDA | Quarter		2
Minimum quick ratio	1.25	1
Covenant, minimum available funds		$ 30,000,000
Credit agreement, borrowing base components, percentage of eligible accounts receivable and advance billings		85.00%
Credit agreement, borrowing base components, percentage of eligible inventory minus reserves		50.00%
Commitment fee				$ 62,500
Revolving credit facility | Amended agreement No. 4 | Alternative base rate
Line of Credit Facility [Line Items]
Variable rate		0.00%
Revolving credit facility | Amended agreement No. 4 | Eurodollar rate
Line of Credit Facility [Line Items]
Variable rate		2.75%

RESTRUCTURING CHARGES - Summary

RESTRUCTURING CHARGES - Summary of Changes in Restructuring Accrual (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Reserve [Roll Forward]
Restructuring Reserve - Beginning Balance	$ 366	$ 1,103	$ 3,605
Restructuring charges	0	412	3,662
Payments	(328)	(1,097)	(6,127)
Reserve adjustments	(30)	(52)	(37)
Restructuring Reserve - Ending Balance	8	366	1,103
Employee severance costs
Restructuring Reserve [Roll Forward]
Restructuring Reserve - Beginning Balance	128	0	2,005
Restructuring charges	0	506	2,413
Payments	(123)	(358)	(4,406)
Reserve adjustments	(5)	(20)	(12)
Restructuring Reserve - Ending Balance	0	128	0
Contract termination costs
Restructuring Reserve [Roll Forward]
Restructuring Reserve - Beginning Balance	238	1,103	1,600
Restructuring charges	0	(94)	825
Payments	(205)	(739)	(1,322)
Reserve adjustments	(25)	(32)	0
Restructuring Reserve - Ending Balance	8	238	1,103
Other costs
Restructuring Reserve [Roll Forward]
Restructuring Reserve - Beginning Balance	0	0	0
Restructuring charges	0	0	424
Payments	0	0	(399)
Reserve adjustments	0	0	(25)
Restructuring Reserve - Ending Balance	$ 0	$ 0	$ 0

RESTRUCTURING CHARGES - Narrati

RESTRUCTURING CHARGES - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)facility	Dec. 31, 2012USD ($)	Dec. 31, 2011vacant_facility
Restructuring Cost and Reserve [Line Items]
Number of vacant facilities | vacant_facility					2
Restructuring charges	$ 0	$ 412	$ 3,662
Payments	(328)	(1,097)	$ (6,127)
Restructuring and other charges	2,500
Number of vacated leased facilities | facility			2
Accrued professional fees and deal-related costs	2,500
Accrued restructuring charges	8	366	$ 1,103	$ 3,605
Employee severance costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	506	2,413
Payments	(123)	(358)	(4,406)
Severance expense			600
Accrued restructuring charges	0	128	0	2,005
Employee severance and other costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			2,800
Payments			(4,800)
Contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	(94)	825
Payments	(205)	(739)	(1,322)
Accrued restructuring charges	$ 8	$ 238	$ 1,103	$ 1,600

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Summary of Changes in Product Warranty Accrual (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Product Warranty, Increase (Decrease) [Roll Forward]
Beginning balance	$ 2,803	$ 1,786	$ 1,691
Warranties issued in the period	3,021	2,783	2,031
Costs to service warranties	(3,974)	(3,059)	(1,981)
Warranty accrual adjustments	1,190	1,293	45
Ending balance	$ 3,040	$ 2,803	$ 1,786

COMMITMENTS AND CONTINGENCIES48

COMMITMENTS AND CONTINGENCIES - Schedule of Minimum Annual Lease Commitments with Respect to Operating Leases (Details) $ in Thousands	Dec. 31, 2015USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016	$ 2,378
2,017	2,288
2,018	2,235
2,019	2,272
2,020	2,324
Thereafter	13,329
Total	$ 24,826

COMMITMENTS AND CONTINGENCIES49

COMMITMENTS AND CONTINGENCIES - Narrative (Details) CAD in Millions	Jan. 07, 2016USD ($)	May. 31, 2007USD ($)	May. 31, 2012USD ($)	Apr. 30, 2012USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Apr. 30, 2013violation	Dec. 31, 2015CAD	Dec. 31, 2015CAD
Loss Contingencies [Line Items]
General length of product warranty					12 months
Rent expense					$ 3,700,000	$ 4,100,000	$ 3,900,000
Operating leases, future minimum payments, at end of lease term					13,329,000
Restricted cash					$ 1,811,000	1,993,000
Suspended payment period for remaining civil penalty								1 year
Vortek Industries
Loss Contingencies [Line Items]
Royalty guarantees payments, percentage of net sales from certain Flash RTP products					1.40%					1.40%
Vortek Industries | Royalty agreements
Loss Contingencies [Line Items]
Potential cash payment to Canadian Minister of Industries from certain Flash RTP products in connection with acquisition of Vortek Industries, Ltd.					$ 10,300,000					CAD 14.3
Cumulative royalty charges to date | CAD									CAD 0.6
Financial standby letter of credit
Loss Contingencies [Line Items]
Maximum potential amount required to pay under outstanding standby letters of credit					1,700,000
Regulatory violations
Loss Contingencies [Line Items]
Civil penalty				$ 900,000
Payment for civil penalty			$ 300,000
Remaining civil penalty contingency			$ 600,000
Number of violations | violation								0
Exton, Pennsylvania and Vancouver, Canada
Loss Contingencies [Line Items]
Sublease revenue					$ 200,000	$ 200,000	$ 400,000
Fremont, California
Loss Contingencies [Line Items]
Term of contract		10 years
Operating lease initial base rent cost		$ 1,400,000
Annual rent increase percentage		3.50%
Operating leases, future minimum payments, at end of lease term		$ 1,500,000
Fremont, California | Financial standby letter of credit
Loss Contingencies [Line Items]
Standby letter of credit		$ 1,500,000
Fremont, California | Subsequent Event
Loss Contingencies [Line Items]
Operating lease initial base rent cost	$ 1,600,000
Annual rent increase percentage	3.00%

STOCKHOLDERS' EQUITY - Narrativ

STOCKHOLDERS' EQUITY - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 28, 2005
Class of Stock [Line Items]
Shares issued in connection with public offering, net of offering costs (in shares)	14,100,000
Price per share (in usd per share)	$ 2.45
Proceeds from issuance of common stock, net	$ 31,700		$ 1,701	$ 32,213	$ 576
Underwriting discounts and offering expenses	$ 2,800
Total purchase price		$ 34,149	87,524	75,110	34,149	$ 43,292
Other income (expense) related to liquidation of subsidiaries			$ (208)	$ 335	$ (10)
Stockholder Rights Plan [Member]
Class of Stock [Line Items]
Share purchase right (in shares)							1
Treasury Stock
Class of Stock [Line Items]
Treasury stock, outstanding (in shares)		(4,181,000)	(4,410,000)	(4,258,000)	(4,181,000)	(4,181,000)
Total purchase price		$ (37,986)	$ (38,640)	$ (38,083)	$ (37,986)	$ (37,986)
Foreign currency translation adjustments | Reclassification out of AOCI
Class of Stock [Line Items]
Other income (expense) related to liquidation of subsidiaries		$ 500

STOCKHOLDERS' EQUITY - Schedule

STOCKHOLDERS' EQUITY - Schedule of Activity in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ 18,171	$ 20,830
Change in currency translation adjustment, net of tax	(1,882)	(2,659)	$ (148)
Balance at end of period	16,289	18,171	20,830
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	18,171	20,830	20,978
Reclassification to earnings, net of tax	0	0	(488)
Change in currency translation adjustment, net of tax		(2,659)	340
Balance at end of period	16,289	18,171	20,830
Unrealized investment gain
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	0	0	29
Reclassification to earnings, net of tax	0	0	(29)
Balance at end of period	$ 0	$ 0	$ 0

EMPLOYEE STOCK PLANS - Narrativ

EMPLOYEE STOCK PLANS - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	May. 28, 2015	May. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of options vesting on first anniversary of vesting commencement date				25.00%
Options granted in period (in shares)				716,000	746,000	1,600,000
Options, grant date fair value				$ 1.2	$ 0.9	$ 1.4
Defined contribution plan, employer discretionary contribution amount				$ 0.2	$ 0.2	$ 0.1
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate				2.78%
Time-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate			25.00%
Time-based restricted stock units | Prior to May 28, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant ratio				1.75
Time-based restricted stock units | On or after May 28, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant ratio				1
2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future grant (in shares)				4,100,000
Number of shares of additional common stock approved (in shares)	2,500,000
Number of shares reserved for issuance (in shares)	19,500,000
Grant ratio	1.75
2012 Equity Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price, as a percent of fair market value of common stock on grant date				100.00%
Percent of options vesting on first anniversary of vesting commencement date				25.00%
Vesting period				36 months
Employee requisite service period			1 year
2012 Equity Incentive Plan | Maximum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award terms				7 years
1994 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP extended term		10 years
ESPP offering period				6 months
1994 Plan | Employee stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future grant (in shares)				2,400,000
Number of shares reserved for issuance (in shares)				6,200,000
Exercise price, as a percent of fair market value of common stock on grant date				90.00%
Maximum employee subscription rate				15.00%
Maximum number of shares per employee (in shares)				4,000		2,000
Shares issued in period (in shares)				100,000
Average price of shares purchased, per share (in usd per share)			$ 2.09	$ 2.99	$ 2.17	$ 2.09

EMPLOYEE STOCK PLANS - Summary

EMPLOYEE STOCK PLANS - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Outstanding, beginning balance (in shares)	4,920	4,993
Granted (in shares)	716	746	1,600
Exercised (in shares)	(1,017)	(486)
Forfeited or expired (in shares)	(447)	(333)
Outstanding, ending balance (in shares)	4,172	4,920	4,993
Vested and expected to vest (in shares)	3,928
Exercisable (in shares)	2,785
Weighted-Average Exercise Price
Weighted-Average Exercise Price Per Share, beginning balance (in usd per share)	$ 2.01	$ 2.18
Weighted Average Exercise Price Per Share, Granted (in usd per share)	3.37	2.42
Weighted Average Exercise Price Per Share, Exercised (in usd per share)	1.91	1.03
Weighted Average Exercise Price Per Share, Forfeited or expired (in usd per share)	4.16	7.01
Weighted-Average Exercise Price Per Share, ending balance (in usd per share)	2.04	$ 2.01	$ 2.18
Weighted Average Exercise Price, Vested and expected to vest (in usd per share)	2
Weighted Average Exercise Price, Exercisable (in usd per share)	$ 1.80
Weighted Average Remaining Term
Weighted Average Remaining Contractual Life	4 years 1 month 15 days	4 years 2 months 12 days	4 years 10 months 24 days
Weighted Average Remaining Contractual Life, Vested and expected to vest	4 years
Weighted Average Remaining Contractual Life, Exercisable	3 years 6 months
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 6,254	$ 7,513	$ 5,281
Aggregate Intrinsic Value, Vested and expected to vest	6,059
Aggregate Intrinsic Value, Exercisable	$ 4,818

EMPLOYEE STOCK PLANS - Schedule

EMPLOYEE STOCK PLANS - Schedule of Supplemental Information Pertaining to Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Weighted-average fair value of options granted (in usd per share)	$ 1.70	$ 1.24	$ 0.87
Intrinsic value of options exercised	$ 2,449	$ 685	$ 386
Cash received from options exercised	$ 1,940	$ 502	$ 445

EMPLOYEE STOCK PLANS - Summar55

EMPLOYEE STOCK PLANS - Summary of Restricted Stock Unit Activity (Details) - Restricted stock units - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Number of Shares
Outstanding, beginning balance	877	429
Granted (in shares)	994	697
Released (in shares)	(462)	(232)
Forfeited or Expired (in shares)	(120)	(17)
Outstanding, ending balance	1,289	877
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, beginning balance (in usd per share)	$ 2.06	$ 1.45
Weighted Average Grant Date Fair Value, Granted (in usd per share)	3.33	2.42
Weighted Average Grant Date Fair Value, Released (in usd per share)	2.57	1.99
Weighted Average Grant Date Fair Value, Forfeited or Expired (in usd per share)	2.86	2.49
Weighted Average Grant Date Fair Value, ending balance (in usd per share)	$ 2.78	$ 2.06

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of Black-Scholes Valuation Model used to Determine Fair Value of Stock Options (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Black-Scholes Valuation Assumptions
Expected dividend yield	0.00%
Stock options
Black-Scholes Valuation Assumptions
Expected dividend yield	0.00%	0.00%	0.00%
Expected stock price volatility	66.00%	67.00%	83.00%
Risk-free interest rate	1.20%	1.30%	0.90%
Expected life of options in years	4 years	4 years	4 years 4 months 22 days

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Unrecognized stock-based compensation	$ 1.3
Weighted average recognition period for stock-based compensation	2 years 2 months 12 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation	$ 2.6
Weighted average recognition period for stock-based compensation	2 years 6 months

STOCK-BASED COMPENSATION - Sche

STOCK-BASED COMPENSATION - Schedule of Stock-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 2,280	$ 1,526	$ 1,433
Cost of goods sold
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	167	40	52
Research, development and engineering
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	253	181	254
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	1,860	1,305	1,127
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	1,018	994	1,289
Restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	1,227	484	124
Employee Stock Purchase Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 35	$ 48	$ 20

GEOGRAPHIC AND CUSTOMER CONCE59

GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION - Narrative (Details)	12 Months Ended
	Dec. 31, 2015reportable_segmentsegmentcustomer	Dec. 31, 2014customer	Dec. 31, 2013customer
Concentration Risk [Line Items]
Number of operating segment | segment	1
Number of reportable segment | reportable_segment	1
Customer concentration risk | Net revenue
Concentration Risk [Line Items]
Number of major customers	2	1	2
Customer concentration risk | Net revenue | Net revenue, major customer A
Concentration Risk [Line Items]
Concentration risk percentage	54.00%	61.00%	35.00%
Customer concentration risk | Net revenue | Net revenue, major customer B
Concentration Risk [Line Items]
Concentration risk percentage	11.00%		33.00%
Customer concentration risk | Accounts receivable
Concentration Risk [Line Items]
Number of major customers	5	1
Customer concentration risk | Accounts receivable | Net accounts receivable, major customer A
Concentration Risk [Line Items]
Concentration risk percentage	36.00%	74.00%
Customer concentration risk | Accounts receivable | Net accounts receivable, major customer B
Concentration Risk [Line Items]
Concentration risk percentage	12.00%
Customer concentration risk | Accounts receivable | Net accounts receivable, major customer C
Concentration Risk [Line Items]
Concentration risk percentage	12.00%
Customer concentration risk | Accounts receivable | Net accounts receivable, major customer D
Concentration Risk [Line Items]
Concentration risk percentage	11.00%
Customer concentration risk | Accounts receivable | Net accounts receivable, major customer E
Concentration Risk [Line Items]
Concentration risk percentage	10.00%

GEOGRAPHIC AND CUSTOMER CONCE60

GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION - Summary of Net Revenue by Geographic Areas Based on the Installation Locations of the Systems and the Location of Services Rendered (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 32,049	$ 38,894	$ 43,334	$ 58,254	$ 54,747	$ 38,430	$ 42,029	$ 43,198	$ 172,532	$ 178,404	$ 119,434
Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									100.00%	100.00%	100.00%
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 25,061	$ 25,716	$ 12,350
United States | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									15.00%	14.00%	10.00%
Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 73,798	$ 87,585	$ 22,173
Korea | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									43.00%	49.00%	19.00%
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 17,537	$ 32,304	$ 50,782
Taiwan | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									10.00%	18.00%	43.00%
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 29,209	$ 17,369	$ 20,250
China | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									17.00%	10.00%	17.00%
Other Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 19,560	$ 6,869	$ 8,740
Other Asia | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									11.00%	4.00%	7.00%
Europe and others
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 7,367	$ 8,561	$ 5,139
Europe and others | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									4.00%	5.00%	4.00%

GEOGRAPHIC AND CUSTOMER CONCE61

GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION - Summary of Geographic Information Relating to Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 8,236	$ 7,534
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	3,350	4,140
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	4,712	3,185
Others
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 174	$ 209

INCOME TAXES - Schedule of Comp

INCOME TAXES - Schedule of Components of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Domestic income (loss)	$ 8,104	$ 7,248	$ (21,743)
Foreign income	3,073	2,972	10,226
Income (loss) before income taxes	$ 11,177	$ 10,220	$ (11,517)

INCOME TAXES - Schedule of Prov

INCOME TAXES - Schedule of Provision for (Benefit from) Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 0	$ 0	$ (466)
State	51	28	52
Foreign	667	160	(125)
Total current	718	188	(539)
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	144	151	(3)
Total deferred	144	151	(3)
Provisions for (benefit from) income taxes	$ 862	$ 339	$ (542)

INCOME TAXES - Schedule of Pr64

INCOME TAXES - Schedule of Provision for (Benefit from) Income Taxes Reconciliation to Amount Computed by Multiplying Income (Loss) Before Income Taxes by the U.S. Statutory Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Benefits at statutory rate	$ 3,912	$ 3,577	$ (4,031)
Deferred tax asset valuation allowance	(3,705)	(3,182)	5,256
Foreign earnings taxed at U.S. rates	208	403	1,966
Foreign earnings taxed at different rates	(388)	(540)	(3,315)
State taxes, net of Federal benefit	416	18	34
Nondeductible stock option expense	173	244	322
Uncertain tax position reserve release	41	(188)	(579)
Other	205	7	(195)
Provisions for (benefit from) income taxes	$ 862	$ 339	$ (542)

INCOME TAXES - Schedule of Defe

INCOME TAXES - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 159,722	$ 161,422
Reserves not currently deductible	6,106	7,547
Tax credit carryforwards	849	849
Depreciation	5,073	6,006
Deferred revenue	1,749	1,186
Other	1,599	(161)
Total deferred tax asset	175,098	176,849
Valuation allowance	(173,081)	(176,786)
Net deferred tax asset	2,017	63
Deferred tax liability	(2,291)	(192)
Net deferred tax asset (liability)	$ (274)	$ (129)

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
U.S. statutory rate	35.00%	35.00%	35.00%
Undistributed earnings of foreign subsidiaries	$ 400,000
Unrecognized tax benefits	24,300,000
Unrecognized tax benefits that would impact effective tax rate	200,000
Decrease in unrecognized tax benefits within the next twelve months	0
Unrecognized tax benefits, interest on income taxes expense	0	$ 100,000	$ 100,000
Unrecognized tax benefits, interest on income taxes accrued	100,000	100,000
Accruals for estimated penalties	0	$ 0
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	447,900,000
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	113,000,000
Canada | Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	38,000,000
Germany | Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	29,200,000
Research credit carryforward | Federal
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	2,700,000
Research credit carryforward | State
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	$ 4,000,000

INCOME TAXES - Schedule of Reco

INCOME TAXES - Schedule of Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 25,100	$ 25,500	$ 25,900
Tax positions related to current and prior years:
Additions	0	0	1,000
Reductions	0	(100)	(100)
Expiration of statutes of limitations	(800)	(300)	(1,300)
Balance at the end of the year	$ 24,300	$ 25,100	$ 25,500

NET INCOME (LOSS) PER SHARE - S

NET INCOME (LOSS) PER SHARE - Schedule of Computation of Net Income (Loss) per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income (loss)	$ (594)	$ 2,023	$ 2,581	$ 6,305	$ 4,963	$ 537	$ 1,916	$ 2,465	$ 10,315	$ 9,881	$ (10,975)
Denominator:
Weighted-average shares outstanding - basic (in shares)	75,287	75,129	74,920	74,700	73,861	73,731	73,532	66,275	74,916	71,897	58,944
Effect of dilutive stock options and restricted stock units (in shares)									1,899	1,506	0
Weighted-average shares outstanding - diluted (in shares)	75,287	76,546	77,019	77,265	75,486	75,023	74,679	67,971	76,815	73,403	58,944
Net income (loss) per share of common stock:
Basic (in usd per share)	$ (0.01)	$ 0.03	$ 0.03	$ 0.08	$ 0.07	$ 0.01	$ 0.03	$ 0.04	$ 0.14	$ 0.14	$ (0.19)
Diluted (in usd per share)	$ (0.01)	$ 0.03	$ 0.03	$ 0.08	$ 0.07	$ 0.01	$ 0.03	$ 0.04	$ 0.13	$ 0.13	$ (0.19)

NET INCOME (LOSS) PER SHARE - N

NET INCOME (LOSS) PER SHARE - Narrative (Details) - shares shares in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock options and restricted stock units
Schedule of Earnings Per Share [Line Items]
Total number of options to purchase common stock and restricted stock units, outstanding (in shares)	1.2	2.3	4.7

SUBSEQUENT EVENT (Details)

SUBSEQUENT EVENT (Details) - USD ($) $ in Thousands, shares in Millions	1 Months Ended	12 Months Ended
	Feb. 28, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Subsequent Event [Line Items]
Shares issued in connection with public offering, net of offering costs (in shares)	14.1
Proceeds from issuance of common stock, net	$ 31,700	$ 1,701	$ 32,213	$ 576

SUPPLEMENTARY FINANCIAL INFOR71

SUPPLEMENTARY FINANCIAL INFORMATION - Schedule of Selected Unaudited Financial Data for Each Quarter (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Net revenue	$ 32,049	$ 38,894	$ 43,334	$ 58,254	$ 54,747	$ 38,430	$ 42,029	$ 43,198	$ 172,532	$ 178,404	$ 119,434
Gross margin	13,787	13,547	16,019	21,394	17,877	12,998	13,296	14,646	64,747	58,817	37,406
Income (loss) from operations	(162)	1,702	2,677	7,303	4,817	546	2,049	2,701	11,520	10,113	(11,013)
Net income (loss)	$ (594)	$ 2,023	$ 2,581	$ 6,305	$ 4,963	$ 537	$ 1,916	$ 2,465	$ 10,315	$ 9,881	$ (10,975)
Net income (loss) per share:
Basic (in usd per share)	$ (0.01)	$ 0.03	$ 0.03	$ 0.08	$ 0.07	$ 0.01	$ 0.03	$ 0.04	$ 0.14	$ 0.14	$ (0.19)
Diluted (in usd per share)	$ (0.01)	$ 0.03	$ 0.03	$ 0.08	$ 0.07	$ 0.01	$ 0.03	$ 0.04	$ 0.13	$ 0.13	$ (0.19)
Shares used in computing net income (loss) per share:
Basic (in shares)	75,287	75,129	74,920	74,700	73,861	73,731	73,532	66,275	74,916	71,897	58,944
Diluted (in shares)	75,287	76,546	77,019	77,265	75,486	75,023	74,679	67,971	76,815	73,403	58,944

SCHEDULE II - VALUATION AND Q72

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 669	$ 704	$ 541
Charged (Credited) to Income	3	0	163
Deduction and Other	0	(35)	0
Balance at End of Year	672	669	704
Deferred Tax Asset Valuation Allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	176,786	181,499	175,300
Charged (Credited) to Income	0	0	6,199
Deduction and Other	(3,705)	(4,713)	0
Balance at End of Year	$ 173,081	$ 176,786	$ 181,499