ACM Research (ACMR) 10-Q 9 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 03, 2020
Entity Listings [Line Items]
Entity Registrant Name	ACM Research, Inc.
Entity Central Index Key	0001680062
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-38273
Entity Tax Identification Number	94-3290283
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	42307 Osgood Road, Suite I
Entity Address, City or Town	Fremont
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94539
City Area Code	510
Local Phone Number	445-3700
Title of 12(b) Security	Class A Common Stock, $0.0001 par value
Trading Symbol	ACMR
Security Exchange Name	NASDAQ
Class A Common Stock [Member]
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		16,662,218
Class B Common Stock [Member]
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		1,802,606

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 92,203	$ 58,261
Restricted cash	0	59,598
Trading securities (note 11)	23,888	0
Accounts receivable, less allowance for doubtful accounts of $0 as of September 30, 2020 and December 31, 2019 (note 3)	59,796	31,091
Other receivables	6,177	2,603
Inventories (note 4)	64,182	44,796
Prepaid expenses	5,531	2,047
Total current assets	251,777	198,396
Property, plant and equipment, net (note 5)	5,974	3,619
Land use right, net (note 2)	9,284	0
Operating lease right-of-use assets, net (note 8)	4,568	3,887
Intangible assets, net	335	344
Deferred tax assets (note 17)	10,093	5,331
Long-term investments (note 10)	6,580	5,934
Other long-term assets	8,008	192
Total assets	296,619	217,703
Current liabilities:
Short-term borrowings (note 6)	28,327	13,753
Accounts payable	35,639	13,262
Advances from customers	8,011	9,129
Income taxes payable	3,589	3,129
Other payables and accrued expenses (note 7)	18,494	12,874
Current portion of operating lease liability (note 8)	1,388	1,355
Deferred revenue	819	0
Total current liabilities	96,267	53,502
Long-term operating lease liability (note 8)	3,180	2,532
Other long-term liabilities (note 9)	6,454	4,186
Total liabilities	105,901	60,220
Commitments and contingencies (note 18)
Redeemable non-controlling interests (note 15)	0	60,162
Stockholders' equity:
Additional paid in capital	100,145	83,487
Accumulated surplus	25,758	15,507
Accumulated other comprehensive income (loss)	1,037	(1,675)
Total ACM Research, Inc. stockholders' equity	126,942	97,321
Non-controlling interests	63,776	0
Total stockholders' equity	190,718	97,321
Total liabilities, redeemable non-controlling interests, and stockholders' equity	296,619	217,703
Class A Common Stock [Member]
Stockholders' equity:
Common stock	2	2
Class B Common Stock [Member]
Stockholders' equity:
Common stock	$ 0	$ 0

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 0	$ 0
Class A Common Stock [Member]
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	16,657,135	16,182,151
Common stock, shares outstanding (in shares)	16,657,135	16,182,151
Class B Common Stock [Member]
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,409,738	2,409,738
Common stock, shares issued (in shares)	1,802,606	1,862,608
Common stock, shares outstanding (in shares)	1,802,606	1,862,608

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) [Abstract]
Revenue	$ 47,665	$ 33,427	$ 111,062	$ 82,916
Cost of revenue	27,324	17,173	61,137	44,705
Gross profit	20,341	16,254	49,925	38,211
Operating expenses:
Sales and marketing	3,924	3,886	11,524	8,679
Research and development	4,343	3,492	13,241	9,598
General and administrative	4,568	1,846	9,100	5,992
Total operating expenses, net	12,835	9,224	33,865	24,269
Income from operations	7,506	7,030	16,060	13,942
Interest income	179	95	834	128
Interest expense	(272)	(205)	(611)	(538)
Change in fair value of financial liability	(6,533)	0	(11,964)	0
Unrealized gain on trading securities	8,970	0	8,970	0
Other income (expense), net	(1,759)	1,850	(933)	2,132
Equity income (loss) in net income (loss) of affiliates	182	(9)	539	260
Income before income taxes	8,273	8,761	12,895	15,924
Income tax benefit (expense) (note 17)	1,747	328	(416)	(667)
Net income	10,020	9,089	12,479	15,257
Less: Net income attributable to non-controlling interests and redeemable non-controlling interests	1,393	307	2,228	307
Net income attributable to ACM Research, Inc.	8,627	8,782	10,251	14,950
Comprehensive income:
Net income	10,020	9,089	12,479	15,257
Foreign currency translation adjustment	5,757	(2,591)	4,099	(2,902)
Comprehensive Income	15,777	6,498	16,578	12,355
Less: Comprehensive income attributable to non-controlling interests and redeemable non-controlling interests	2,698	307	3,614	307
Comprehensive income attributable to ACM Research, Inc.	$ 13,079	$ 6,191	$ 12,964	$ 12,048
Net income attributable to ACM Research, Inc. per common share (note 2):
Basic (in dollars per share)	$ 0.47	$ 0.52	$ 0.57	$ 0.91
Diluted (in dollars per share)	$ 0.40	$ 0.45	$ 0.48	$ 0.80
Weighted average common shares outstanding used in computing per share amounts (note 2):
Basic (in shares)	18,201,943	16,999,746	18,124,665	16,381,944
Diluted (in shares)	21,555,296	19,354,214	21,257,661	18,699,010

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]Common Stock Class A [Member]	Common Stock [Member]Common Stock Class B [Member]	Additional Paid-In Capital [Member]	Accumulated Surplus (Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	Total
Beginning balance at Dec. 31, 2018	$ 1	$ 0	$ 56,567	$ (3,387)	$ (857)		$ 52,324
Beginning balance (in shares) at Dec. 31, 2018	14,110,315	1,898,423
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 0	$ 0	0	14,950	0		14,950
Foreign currency translation adjustment	0	0	0	0	(2,220)		(2,220)
Exercise of stock options	$ 0	$ 0	312	0	0		312
Exercise of stock options (in shares)	193,642	0
Cancellation of stock options	$ 0	$ 0	(576)	0	0
Cancellation of stock options (In shares)	0	0
Stock-based compensation	$ 0	$ 0	2,919	0	0		2,919
Issuance of Class A common stock in connection with public offering	$ 1	$ 0	26,462	0	0		26,463
Issuance of Class A common stock in connection with public offering (in shares)	2,053,572	0
Share repurchase\cancellation	$ 0	$ 0	(2,827)	0	0		(2,827)
Share repurchase\cancellation (in shares)	(214,286)	0
Conversion of class B common stock to Class A common stock	$ 0	$ 0	0	0	0		0
Conversion of class B common stock to Class A common stock (in shares)	35,815	(35,815)
Ending balance at Sep. 30, 2019	$ 2	$ 0	82,857	11,563	(3,077)		91,345
Ending balance (in shares) at Sep. 30, 2019	16,179,058	1,862,608
Beginning balance at Jun. 30, 2019	$ 1	$ 0	58,101	2,781	(1,168)		59,715
Beginning balance (in shares) at Jun. 30, 2019	14,229,942	1,883,423
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 0	$ 0	0	8,782	0		8,782
Foreign currency translation adjustment	0	0	0	0	(1,909)		(1,909)
Exercise of stock options	$ 0	$ 0	140	0	0		140
Exercise of stock options (in shares)	89,015	0
Cancellation of stock options		$ 0	(576)	0	0		(576)
Cancellation of stock options (In shares)	0	0
Stock-based compensation	$ 0	$ 0	1,557	0	0		1,557
Issuance of Class A common stock in connection with public offering	$ 1	$ 0	26,462	0	0		26,463
Issuance of Class A common stock in connection with public offering (in shares)	2,053,572	0
Share repurchase\cancellation	$ 0	$ 0	(2,827)	0	0		(2,827)
Share repurchase\cancellation (in shares)	(214,286)	0
Conversion of class B common stock to Class A common stock	$ 0	$ 0	0	0	0		0
Conversion of class B common stock to Class A common stock (in shares)	20,815	(20,815)
Ending balance at Sep. 30, 2019	$ 2	$ 0	82,857	11,563	(3,077)		91,345
Ending balance (in shares) at Sep. 30, 2019	16,179,058	1,862,608
Beginning balance at Dec. 31, 2019	$ 2	$ 0	83,487	15,507	(1,675)	$ 0	97,321
Beginning balance (in shares) at Dec. 31, 2019	16,182,151	1,862,608
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 0	$ 0	0	10,251	0	1,585	11,836
Foreign currency translation adjustment	0	0	0	0	2,712	2,233	4,945
Exercise of stock options	$ 0	$ 0	2,191	0	0	0	2,191
Exercise of stock options (in shares)	592,946	0
Stock-based compensation	$ 0	$ 0	4,323	0	0	0	4,323
Share repurchase\cancellation	$ 0	$ 0	(9,715)	0	0	0	(9,715)
Share repurchase\cancellation (in shares)	(242,681)	0
Conversion of class B common stock to Class A common stock	$ 0	$ 0	0	0	0	0	0
Conversion of class B common stock to Class A common stock (in shares)	60,002	(60,002)
Issuance of warrants (note 12)	$ 0	$ 0	19,859	0	0	0	19,859
Exercise of stock warrant	$ 0	$ 0	0	0	0	0	0
Exercise of stock warrant (in shares)	64,717	0
Reclassification of redeemable non-controlling interest	$ 0	$ 0	0	0	0	59,958	59,958
Ending balance at Sep. 30, 2020	$ 2	$ 0	100,145	25,758	1,037	63,776	190,718
Ending balance (in shares) at Sep. 30, 2020	16,657,135	1,802,606
Beginning balance at Jun. 30, 2020	$ 2	$ 0	76,189	17,131	(3,415)	61,078	150,985
Beginning balance (in shares) at Jun. 30, 2020	16,250,092	1,802,606
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 0	$ 0	0	8,627	0	1,393	10,020
Foreign currency translation adjustment	0	0	0	0	4,452	1,305	5,757
Exercise of stock options	$ 0	$ 0	1,318	0	0	0	1,318
Exercise of stock options (in shares)	407,043	0
Stock-based compensation	$ 0	$ 0	2,779	0	0	0	2,779
Issuance of warrants (note 12)	0	0	19,859	0	0	0	19,859
Ending balance at Sep. 30, 2020	$ 2	$ 0	$ 100,145	$ 25,758	$ 1,037	$ 63,776	$ 190,718
Ending balance (in shares) at Sep. 30, 2020	16,657,135	1,802,606

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 12,479	$ 15,257
Adjustments to reconcile net income from operations to net cash used in operating activities:
Depreciation and amortization	774	586
Loss on disposals of property, plant and equipment	1	296
Equity income in net income of affiliates	(539)	(260)
Unrealized gain on trading securities	(8,970)	0
Deferred income taxes	(4,632)	(757)
Stock-based compensation	4,323	2,919
Change in fair value of financial liability	11,964	0
Net changes in operating assets and liabilities:
Accounts receivable	(27,575)	(19,634)
Other receivables	(3,512)	1,187
Inventory	(18,362)	(5,889)
Prepaid expenses	(3,371)	323
Other long-term assets	(839)	(182)
Accounts payable	22,023	(417)
Advances from customers	(1,142)	746
Income tax payable	389	162
Other payables and accrued expenses	5,962	2,352
Deferred revenue	819	0
Other long-term liabilities	2,172	(1,441)
Net cash flow used in operating activities	(8,036)	(4,752)
Cash flows from investing activities:
Purchase of property and equipment	(3,583)	(832)
Purchase of intangible assets	(81)	(114)
Purchase of land-use-right	(9,331)	0
Purchase of trading securities	(14,680)	0
Prepayment for property	(6,978)	0
Investments in unconsolidated affiliates	0	(4,348)
Net cash used in investing activities	(34,653)	(5,294)
Cash flows from financing activities:
Proceeds from short-term borrowings	31,068	18,267
Repayments of short-term borrowings	(16,881)	(11,770)
Repayments of notes payable	(1,820)	0
Proceeds from stock option exercise to common stock	2,191	312
Proceeds from issuance of Class A common stock in connection with public offering, net of direct issuance expenses of $2,287	0	26,463
Payment for repurchase of Class A common stock	0	(785)
Payment for cancellation of stock option	0	(576)
Proceeds from issuance of common stock to redeemable Non-controlling interest	0	27,264
Net cash provided by financing activities	14,558	59,175
Effect of exchange rate changes on cash, cash equivalents and restricted cash	2,475	(2,407)
Net increase (decrease) in cash, cash equivalents and restricted cash	(25,656)	46,722
Cash, cash equivalents and restricted cash at beginning of period	117,859	27,124
Cash, cash equivalents and restricted cash at end of period	92,203	73,846
Supplemental disclosure of cash flow information:
Interest paid	611	538
Cash paid for income taxes	4,606	0
Reconciliation of cash, cash equivalents and restricted cash in condensed consolidated statements of cash flows:
Cash and cash equivalents	92,203	47,264
Restricted cash	0	26,582
Non-cash financing activities:
Warrant conversion to common stock	399	0
Share cancellation, note 12	9,715	0
Issuance of warrant for settlement of financial liability and cancellation of note receivable	$ 19,859	$ 0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Cash flows from financing activities:
Direct issuance expenses	$ 2,287

DESCRIPTION OF BUSINESS

DESCRIPTION OF BUSINESS	9 Months Ended
	Sep. 30, 2020
DESCRIPTION OF BUSINESS [Abstract]
DESCRIPTION OF BUSINESS	NOTE 1 – DESCRIPTION OF BUSINESS ACM Research, Inc. (“ACM”) and its subsidiaries (collectively with ACM, the “Company”) develop, manufacture and sell single-wafer wet cleaning equipment used to improve the manufacturing process and yield for advanced integrated chips. The Company markets and sells its single-wafer wet-cleaning equipment, under the brand name “Ultra C,” based on the Company’s proprietary Space Alternated Phase Shift (“SAPS”) and Timely Energized Bubble Oscillation (“TEBO”) technologies. These tools are designed to remove random defects from a wafer surface efficiently, without damaging the wafer or its features, even at increasingly advanced process nodes. ACM was incorporated in California in 1998, and it initially focused on developing tools for manufacturing process steps involving the integration of ultra low-K materials and copper. The Company’s early efforts focused on stress-free copper-polishing technology, and it sold tools based on that technology in the early 2000s. In 2006 the Company established its operational center in Shanghai in the People’s Republic of China (the “PRC”), where it operates through ACM’s subsidiary ACM Research (Shanghai), Inc. (“ACM Shanghai”). ACM Shanghai was formed initially in 2005 to help establish and build relationships with integrated circuit manufacturers in the PRC, and the Company initially financed its Shanghai operations in part through sales of non-controlling equity interests in ACM Shanghai. In 2007 the Company began to focus its development efforts on single-wafer wet-cleaning solutions for the front-end chip fabrication process. The Company introduced its SAPS megasonic technology, which can be applied in wet wafer cleaning at numerous steps during the chip fabrication process, in 2009. It introduced its TEBO technology, which can be applied at numerous steps during the fabrication of small node two-dimensional conventional and three-dimensional patterned wafers, in March 2016. The Company has designed its equipment models for SAPS and TEBO solutions using a modular configuration that enables it to create a wet-cleaning tool meeting the specific requirements of a customer, while using pre-existing designs for chamber, electrical, chemical delivery and other modules. In August 2018, the Company introduced its Ultra-C Tahoe wafer cleaning tool, which can deliver high cleaning performance with significantly less sulfuric acid than typically consumed by conventional high-temperature single-wafer cleaning tools. The Company also offers a range of custom-made equipment, including cleaners, coaters and developers, to back-end wafer assembly and packaging factories, principally in the PRC. In 2011 ACM Shanghai formed a wholly owned subsidiary in the PRC, ACM Research (Wuxi), Inc. (“ACM Wuxi”), to manage sales and service operations. In June 2017 ACM formed a wholly owned subsidiary in Hong Kong, CleanChip Technologies Limited (“CleanChip”), to act on the Company’s behalf in Asian markets outside the PRC by, for example, serving as a trading partner between ACM Shanghai and its customers, procuring raw materials and components, performing sales and marketing activities, and making strategic investments. In December 2017 ACM formed a wholly owned subsidiary in the Republic of Korea, ACM Research Korea CO., LTD. (“ACM Korea”), to serve customers based in Republic of Korea and perform sales, marketing, research and development activities for new products and solutions. In March 2019 ACM Shanghai formed a wholly owned subsidiary in the PRC, Shengwei Research (Shanghai), Inc. (“ACM Shengwei”), to manage activities related to addition of future long-term production capacity. In June 2019 CleanChip formed a wholly owned subsidiary in California, ACM Research (CA), Inc. (“ACM California”), to provide procurement services on behalf of ACM Shanghai. In June 2019 ACM announced plans to complete over the next three years a listing (the “STAR Listing”) of shares of ACM Shanghai on the Shanghai Stock Exchange’s new Sci-Tech innovAtion boaRd, known as the STAR Market, and a concurrent initial public offering (the “STAR IPO”) of ACM Shanghai shares in the PRC. ACM Shanghai is currently ACM’s primary operating subsidiary, and at the time of announcement, was wholly owned by ACM. To meet a STAR Listing requirement that it have multiple independent stockholders in the PRC, ACM Shanghai completed private placements of its shares in June and November 2019, following which, as of September 30, 2020, the private placement investors held a total of 8.3% of the outstanding shares of ACM Shanghai and ACM Research held the remaining 91.7%. As part of the STAR Listing process, in June 2020 the ownership interests held by the private investors were reclassified from redeemable non-controlling interests to non-controlling interests as the redemption feature was terminated. (Note 15). In preparation for the STAR IPO, the Company completed a reorganization in December 2019 that included the sale of all of the shares of CleanChip by ACM to ACM Shanghai for $3,500. The reorganization and sale had no impact on the Company’s consolidated financial statements. The Company has direct or indirect interests in the following subsidiaries: Effective interest held as at Name of subsidiaries Place and date of incorporation September 30, 2020 December 31, 2019 ACM Research (Shanghai), Inc. China, May 2005 91.7 % 91.7 % ACM Research (Wuxi), Inc. China, July 2011 91.7 % 91.7 % CleanChip Technologies Limited Hong Kong, June 2017 91.7 % 91.7 % ACM Research Korea CO., LTD. Korea, December 2017 91.7 % 91.7 % Shengwei Research (Shanghai), Inc. China, March 2019 91.7 % 91.7 % ACM Research (CA), Inc. USA, June 2019 91.7 % 91.7 % ACM Research (Cayman), Inc. Cayman Islands, April 2019 100.0 % 100.0 %

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2020
SIGNIFICANT ACCOUNTING POLICIES [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	NOTE 2 – SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Principles of Consolidation The Company’s consolidated financial statements include the accounts of ACM and its subsidiaries, including ACM Shanghai and its subsidiaries, which include ACM Wuxi, ACM Shengwei and CleanChip (the subsidiaries of which include ACM California and ACM Korea). ACM’s subsidiaries are those entities in which ACM, directly and indirectly, controls more than one half of the voting power. All significant intercompany transactions and balances have been eliminated upon consolidation. The accompanying condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and the rules and regulations of the Securities and Exchange Commission for reporting on Form 10-Q. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. The unaudited condensed consolidated financial statements herein should be read in conjunction with the historical consolidated financial statements of the Company for the year ended December 31, 2019 included in ACM’s Annual Report on Form 10-K for the year ended December 31, 2019. The accompanying condensed consolidated balance sheet as of September 30, 2020, condensed consolidated statements of operations and comprehensive income for the three and nine months ended September 30, 2020 and 2019, condensed consolidated statements of changes in stockholders’ equity for the three and nine months ended September 30, 2020 and 2019, and condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019 are unaudited. In the opinion of management, the unaudited condensed consolidated financial statements of the Company reflect all adjustments that are necessary for a fair presentation of the Company’s financial position and results of operations. Such adjustments are of a normal recurring nature, unless otherwise noted. The balance sheet as of September 30, 2020 and the results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results to be expected for COVID-19 Assessment The outbreak of COVID-19, the coronavirus, has grown both in the United States and globally, and related government and private sector responsive actions have adversely affected the Company’s business operations. In December 2019 a series of emergency quarantine measures taken by the PRC government disrupted domestic business activities during the weeks after the initial outbreak of COVID-19. Since that time, an increasing number of countries, including the United States, have imposed restrictions on travel to and from the PRC and elsewhere, as well as general movement restrictions, business closures and other measures imposed to slow the spread of COVID-19. The situation continues to develop, however, and it is impossible to predict the effect and ultimate impact of the COVID-19 outbreak on the Company’s business operations and results. While the quarantine, social distancing and other regulatory measures instituted or recommended in response to COVID-19 are expected to be temporary, the duration of the business disruptions, and related financial impact, cannot be estimated at this time. The COVID-19 outbreak has been declared a worldwide health pandemic that could adversely affect the economies and financial markets of many countries, resulting in an economic downturn and changes in global economic policy that could reduce demand for the Company’s products and its customers’ chips and have a material adverse impact on the Company’s business, operating results and financial condition. Through September Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the balance sheet date and the reported revenue and expenses during the reported period in the condensed consolidated financial statements and accompanying notes. The Company’s significant accounting estimates and assumptions include, but are not limited to, those used for the valuation and recognition of stock-based compensation arrangements and valuation of financial liability, realization of deferred tax assets, assessment for impairment of long-lived assets, allowance for doubtful accounts, inventory valuation for excess and obsolete inventories, lower of cost and market value or net realizable value of inventories, depreciable lives of property and equipment, and useful life of intangible assets. Management believes that the estimates, judgments and assumptions are reasonable, based on information available at the time they are made. Actual results could differ materially from those estimates. Basic and Diluted Net Income per Common Share Basic and diluted net income per common share is calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net income $ 10,020 $ 9,089 $ 12,479 $ 15,257 Net income attributable to non-controlling interests and redeemable non-controlling interests 1,393 307 2,228 307 Net income available to common stockholders, basic and diluted $ 8,627 $ 8,782 $ 10,251 $ 14,950 Weighted average shares outstanding, basic 18,201,943 16,999,746 18,124,665 16,381,944 Effect of dilutive securities 3,353,353 2,354,468 3,132,996 2,317,066 Weighted average shares outstanding, diluted 21,555,296 19,354,214 21,257,661 18,699,010 Net income per common share: Basic $ 0.47 $ 0.52 $ 0.57 $ 0.91 Diluted $ 0.40 $ 0.45 $ 0.48 $ 0.80 ACM has been authorized to issue Class A and Class B common stock since redomesticating in Delaware in November 2016. The two classes of common stock are substantially identical in all material respects, except for voting rights. Since ACM did not declare any dividends during the three and nine months ended September Diluted net income per common share reflects the potential dilution from securities that could share in ACM’s earnings. ACM’s potential dilutive securities consist of warrants and stock options for the three and nine months ended September Land use right, net The land use right represents the cost to purchase a right to use state-owned land in the PRC with lease terms of years The land use right is carried at cost less accumulated amortization and impairment losses, if any. Amortization is computed using the straight-line method over the term specified in the land use right certificate, which is years. Concentration of Credit Risk The Company is potentially subject to concentrations of credit risks in its accounts receivable. For the nine months ended September September September Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In August 2018, the Financial Accounting Standards Board Fair Value Measurement (Topic 820) Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815) and Leases (Topic 842), In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes

ACCOUNTS RECEIVABLE

ACCOUNTS RECEIVABLE	9 Months Ended
	Sep. 30, 2020
ACCOUNTS RECEIVABLE [Abstract]
ACCOUNTS RECEIVABLE	NOTE 3 – ACCOUNTS RECEIVABLE At September September 30, 2020 December 31, 2019 Accounts receivable $ 59,796 $ 31,091 Less: Allowance for doubtful accounts - - Total $ 59,796 $ 31,091 The Company reviews accounts receivable on a periodic basis and makes general and specific allowances when there is doubt as to the collectability of individual balances. No allowance for doubtful accounts was considered necessary at September September

INVENTORIES

INVENTORIES	9 Months Ended
	Sep. 30, 2020
INVENTORIES [Abstract]
INVENTORIES	NOTE 4 – INVENTORIES At September September 30, 2020 December 31, 2019 Raw materials $ 27,254 $ 15,105 Work in process 13,882 10,407 Finished goods 23,046 19,284 Total inventory $ 64,182 $ 44,796 System shipments of first-tools to an existing or prospective customer, for which ownership does not transfer until customer acceptance, are classified as finished goods inventory and carried at cost until ownership is transferred.

PROPERTY, PLANT AND EQUIPMENT,

PROPERTY, PLANT AND EQUIPMENT, NET	9 Months Ended
	Sep. 30, 2020
PROPERTY, PLANT AND EQUIPMENT, NET [Abstract]
PROPERTY, PLANT AND EQUIPMENT, NET	NOTE 5 – PROPERTY, PLANT AND EQUIPMENT, NET At September September 30, 2020 December 31, 2019 Manufacturing equipment $ 4,093 $ 3,902 Office equipment 926 627 Transportation equipment 177 124 Leasehold improvement 1,471 1,442 Total cost 6,667 6,095 Less: Total accumulated depreciation (3,751 ) (3,077 ) Construction in progress 3,058 601 Total property, plant and equipment, net $ 5,974 $ 3,619 Depreciation expense was $195 and $176 for the three months ended September 30, 2020 and 2019, respectively, and $ and $ for the nine months ended September 30, 2020 and 2019, respectively

SHORT-TERM BORROWINGS

SHORT-TERM BORROWINGS	9 Months Ended
	Sep. 30, 2020
SHORT-TERM BORROWINGS [Abstract]
SHORT-TERM BORROWINGS	NOTE 6 – SHORT-TERM BORROWINGS At September 30, 2020 and December 31, 2019, short-term borrowings consisted of the following: September 30, 2020 December 31, 2019 Line of credit up to RMB 50,000 from Bank of Shanghai Pudong Branch, due on January 23, 2020 with an annual interest rate of 5.22%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. It was fully repaid on January 23, 2020. $ - $ 5,057 Line of credit up to RMB 20,000 from Shanghai Rural Commercial Bank, due on February 21, 2020 with an annual interest rate of 5.66%, guaranteed by the Company’s CEO and pledged by accounts receivable. It was fully repaid on February 21, 2020. - 1,433 Line of credit up to RMB 20,000 from Bank of Communications, due on January 18, 2020 with an annual interest rate of 5.66% and fully repaid on January 19, 2020. - 1,433 Line of credit up to RMB 20,000 from Bank of Communications, due on January 22, 2020 with an annual interest rate of 5.66% and fully repaid on January 22, 2020. - 717 Line of credit up to RMB 20,000 from Bank of Communications, due on February 14, 2020 with an annual interest rate of 5.66% and fully repaid on February 14, 2020. - 717 Line of credit up to RMB 50,000 from China Everbright Bank, due on March 25, 2020 with an annual interest rate of 4.94%, guaranteed by the Company’s CEO and fully repaid on March 24, 2020. - 3,250 Line of credit up to RMB 50,000 from China Everbright Bank, due on April 17, 2020 with an annual interest rate of 5.66%, guaranteed by the Company’s CEO and fully repaid on April 2, 2020. - 1,146 Line of credit up to RMB 80,000 from China Everbright Bank, due on April 1, 2021 with an annual interest rate of 4.70%, guaranteed by the Company’s CEO. 4,404 - Line of credit up to RMB 80,000 from China Everbright Bank, due on June 27, 2021 with an annual interest rate of 4.25%, guaranteed by the Company’s CEO. 1,321 - Line of credit up to RMB 80,000 from China Everbright Bank, due on April 29, 2021 with an annual interest rate of 2.80%, guaranteed by the Company’s CEO. 820 - Line of credit up to RMB 80,000 from China Everbright Bank, due on June 27, 2021 with an annual interest rate of 2.70%, guaranteed by the Company’s CEO. 2,079 - Line of credit up to RMB 20,000 from Bank of Communications, due on April 12, 2021 with an annual interest rate of 4.65%. 1,468 - Line of credit up to RMB 20,000 from Bank of Communications, due on May 24, 2021 with an annual interest rate of 3.65%. 1,468 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on May 27, 2021 with an annual interest rate of 4.68%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 2,466 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on June 27, 2021 with an annual interest rate of 4.68%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 1,321 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on May 28, 2021 with an annual interest rate of 3.48%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 2,441 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on June 7, 2021 with an annual interest rate of 3.50%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 1,521 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on June 16, 2021 with an annual interest rate of 3.50%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 1,837 - Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on December 17, 2020 with annual interest rate of 4.35%, guaranteed by the Company’s CEO. 2,496 - Line of credit up to RMB 80,000 from China Merchants Bank,due on August 10, 2021 with annual interest rate of 3.85%. 1,321 - Line of credit up to RMB 80,000 from China Merchants Bank,due on August 25, 2021 with annual interest rate of 3.85%. 2,936 - Line of credit up to KRW 500,000 from Industrial Bank of Korea, due on July 11, 2021 with an annual interest rate of 3.99%,guaranteed by the ACM-KOREA CEO. 428 - Total $ 28,327 $ 13,753 Interest expense related to short-term borrowings amounted to $272 and $205 for the three months ended and , respectively, and $ and $ for the months ended and ,

OTHER PAYABLE AND ACCRUED EXPEN

OTHER PAYABLE AND ACCRUED EXPENSES	9 Months Ended
	Sep. 30, 2020
OTHER PAYABLE AND ACCRUED EXPENSES [Abstract]
OTHER PAYABLE AND ACCRUED EXPENSES	NOTE 7 – OTHER PAYABLE AND ACCRUED EXPENSES At September September 30, 2020 December 31, 2019 Accrued commissions $ 7,785 $ 4,082 Accrued warranty 3,449 2,811 Accrued payroll 2,960 2,092 Accrued professional fees 40 165 Accrued machine testing fees 1,481 1,456 Others 2,779 2,268 Total $ 18,494 $ 12,874

LEASES

LEASES	9 Months Ended
	Sep. 30, 2020
LEASES [Abstract]
LEASES	NOTE 8 – LEASES The Company leases space under non-cancelable operating leases for several office and manufacturing locations. These leases do not have significant rent escalation holidays, concessions, leasehold improvement incentives, or other build-out clauses. Further, the leases do not contain contingent rent provisions. Most leases include one or more options to renew. The exercise of lease renewal options is typically at the Company’s sole discretion; therefore, the majority of renewals to extend the lease terms are not included in the Company’s right-of-use assets and lease liabilities as they are not reasonably certain of exercise. The Company regularly evaluates the renewal options, and when they are reasonably certain of exercise, the Company includes the renewal period in its lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of the lease payments. The Company has a centrally managed treasury function; therefore, based on the applicable lease terms and the current economic environment, it applies a portfolio approach for determining the incremental borrowing rate. The components of lease expense were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Operating lease cost $ 384 $ 363 $ 1,139 $ 1,064 Short-term lease cost 73 92 170 117 Lease cost $ 457 $ 455 $ 1,309 $ 1,181 Supplemental cash flow information related to operating leases was as follows for the three and nine-month periods ended September 30, 2020 Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash outflow from operating leases $ 457 $ 455 $ 1,309 $ 1,181 Maturities of lease liabilities for all operating leases were as follows as of September 30, 2020 December 31, 2020 $ 390 2021 1,592 2022 1,580 2023 912 2024 872 2025 22 Total lease payments 5,368 Less: Interest (800 ) Present value of lease liabilities $ 4,568 The weighted average remaining lease terms and discount rates for all operating leases were as follows as of September 30, 2020 and December 31, 2019 September 30, 2020 December 31, 2019 Remaining lease term and discount rate: Weighted average remaining lease term (years) 3.70 3.02 Weighted average discount rate 5.29 % 5.43 %

OTHER LONG-TERM LIABILITIES

OTHER LONG-TERM LIABILITIES	9 Months Ended
	Sep. 30, 2020
OTHER LONG-TERM LIABILITIES [Abstract]
OTHER LONG-TERM LIABILITIES	NOTE 9 – OTHER LONG-TERM LIABILITIES Other long-term liabilities represent subsidies that we have received from governmental authorities, including China’s Ministry of Science and Technology, the Shanghai Municipal Commission of Economy and Information, and the Shanghai Science and Technology Committee, for development and commercialization of certain technology but have not yet earned and recognized. As of September 30, 2020 and December 31, 2019, other long-term liabilities consisted of the following unearned government subsidies: September 30, 2020 December 31, 2019 Subsidies to Stress Free Polishing project, commenced in 2008 and 2017 $ 1,126 $ 1,251 Subsidies to Electro Copper Plating project, commenced in 2014 2,188 2,666 Subsidies to Polytetrafluoroethylene, commenced in 2018 125 135 Subsidies to Tahoe-Single Bench Clean, commenced in 2020 1,962 - Subsidies to Backside Clean-YMTC National Project, commenced in 2020 751 - Other 302 134 Total $ 6,454 $ 4,186

LONG TERM INVESTMENTS

LONG TERM INVESTMENTS	9 Months Ended
	Sep. 30, 2020
LONG TERM INVESTMENTS [Abstract]
LONG TERM INVESTMENTS	NOTE 10 – LONG TERM INVESTMENTS In September 2017, ACM and Ninebell Co., Ltd. (“Ninebell”), a Korean company that is one of the Company’s principal materials suppliers, entered into an ordinary share purchase agreement, pursuant to which Ninebell issued to ACM ordinary shares representing 20% of Ninebell’s post-closing equity for a purchase price of $1,200, and a common stock purchase agreement, pursuant to which ACM issued 133,334 shares of Class A common stock to Ninebell for a purchase price of $1,000 at $7.50 per share. The investment in Ninebell is accounted for under the equity method. On June 27, 2019, ACM Shanghai and Shengyi Semiconductor Technology Co., Ltd. (“Shengyi”), a company based in Wuxi, China that is one of the Company’s components suppliers, entered into an agreement pursuant to which Shengyi issued to ACM Shanghai shares representing 15% of Shengyi’s post-closing equity for a purchase price of $109. The investment in Shengyi is accounted for under the equity method. On September 5, 2019, ACM Shanghai, entered into a Partnership Agreement with six other investors, as limited partners, and Beijing Shixi Qingliu Investment Co., Ltd., as general partner and manager, with respect to the formation of Hefei Shixi Chanheng Integrated Circuit Industry Venture Capital Fund Partnership (LP) (“Hefei Shixi”), a Chinese limited partnership based in Hefei, China. Pursuant to such Partnership Agreement, on September 30, 2019, ACM Shanghai invested $4,200, which represented 10% of the Partnership’s total subscribed capital. The investment in Hefei Shixi Chanheng Integrated Circuit Industry Venture Capital Fund Partnership (LP) is accounted for under the equity method. The components of long-term investments were as follows: September 30, 2020 December 31, 2019 Ninebell $ 2,088 $ 1,538 Shengyi 134 107 Hefei Shixi 4,358 4,289 Total $ 6,580 $ 5,934

TRADING SECURITIES

TRADING SECURITIES	9 Months Ended
	Sep. 30, 2020
TRADING SECURITIES [Abstract]
TRADING SECURITIES	NOTE 11 – TRADING SECURITIES Pursuant to a Partnership Agreement dated June 9, 2020 (the “Partnership Agreement”) and a Supplementary Agreement thereto dated June 15, 2020 (the “Supplementary Agreement”), ACM Shanghai became a limited partner of Qingdao Fortune-Tech Xinxing Capital Partnership (L.P.), a Chinese limited partnership based in Shanghai, China (the “Partnership”) of which China Fortune-Tech Capital Co., Ltd serves as general partner and thirteen unaffiliated entities serve, with ACM Shanghai, as limited partners. The Partnership was formed to establish a special fund that would purchase, in a strategic placement, shares of Semiconductor Manufacturing International Corporation, (“SMIC”) to be listed on the STAR Market. SMIC is a Shanghai-based foundry that has been a customer of the Company’s single-wafer wet-cleaning tools. The limited partners of the Partnership contributed to the fund a total of RMB billion ($ ), of which ACM Shanghai contributed RMB million ($ million), or of the total contribution, on June 18, 2020. Upon the closing of the SMIC offering in July 2020, the initial number of SMIC shares owned by the Partnership was apportioned to all of the limited partners in proportion to their respective capital contributions ( in the case of ACM Shanghai). All of the SMIC shares acquired by the Partnership are subject, under applicable Chinese laws, to lock-up restrictions that prevent sales of the shares for one year after the shares were acquired. Thereafter an individual limited partner will be able to instruct the general partner to sell, on behalf of the limited partner, all or a portion of the limited partner’s apportioned shares, subject to compliance with all laws, regulations, trading rules, the Partnership Agreement and the Supplementary Agreement. Alternatively, following the lock-up period, limited partners holding at least of the total SMIC shares held by the Partnership will be able, pursuant to a call auction in accordance with the Supplementary Agreement, to cause the general partner to arrange to sell all of the shares desired to be offered by each of the limited partners that complies with procedural requirements provided in the Supplementary Agreement. ACM Shanghai’s investment is accounted for as trading securities, and is stated at market value which is classified as Level 2 of the hierarchy established under ASC No. 820 with valuations based on quoted prices for identical securities in active markets, less a discount applied to reflect the remaining lock-up period. The components of trading securities were as follows: September 30, 2020 December 31, 2019 Trading securities listed in Shanghai Stock Exchange Cost $ 14,680 $ - Market value $ 23,888 $ - Unrealized gain on trading securities amounted to $8,970 for the three and nine months ended September 30, 2020.

FINANCIAL LIABILITY CARRIED AT

FINANCIAL LIABILITY CARRIED AT FAIR VALUE	9 Months Ended
	Sep. 30, 2020
FINANCIAL LIABILITY CARRIED AT FAIR VALUE [Abstract]
FINANCIAL LIABILITY CARRIED AT FAIR VALUE	NOTE 12 – FINANCIAL LIABILITY CARRIED AT FAIR VALUE In December 2016 Shengxin (Shanghai) Management Consulting Limited Partnership (“SMC”) paid 20,123,500 RMB ($2,981 as of the date of funding) (the “SMC Investment”) to ACM Shanghai for investment pursuant to terms to be subsequently negotiated. SMC is a PRC limited partnership partially owned by employees of ACM Shanghai. In March 2017 (a) ACM issued to SMC a warrant (the “Warrant”) exercisable to purchase 397,502 shares of Class A common stock at a price of $7.50 per share, for a total exercise price of $2,981, and (b) ACM Shanghai agreed to repay the SMC Investment within 60 days after the exercise of the Warrant. In March 2018 SMC exercised the Warrant in full, as a result of which (1) ACM issued 397,502 shares of Class A common stock to SMC, (2) SMC borrowed the funds to pay the Warrant exercise price pursuant to a senior secured promissory note (the “SMC Note”) in the principal amount of $2,981 issued to ACM Shanghai, which in turn issued to ACM a promissory note (the “Intercompany Note”) in the principal amount of $2,981 in payment of the Warrant exercise price. Each of the SMC Note and the Intercompany Note bears interest at a rate of 3.01% per annum and matures on August 17, 2023. The SMC Note was secured by a pledge of the shares issued upon exercise of the Warrant. In connection with its follow-on public offering of Class A common stock in August 2019, ACM agreed to purchase a total of 154,821 of the Warrant shares from SMC at a per share price of $13.195, of which (a) $1,161 was applied to reduce SMC’s obligations to ACM Shanghai under the SMC Note, and which ACM then withheld for its own account and applied to reduce ACM Shanghai’s obligations to ACM under the Intercompany Note, and (b) the remaining $882 was paid to SMC. In a separate transaction, ACM Shanghai repaid $1,161 of the SMC Investment in cash, which reduced the amount of the SMC Investment due to SMC to $1,820. The SMC Note and SMC Investment are offsetting items in the Company’s consolidated balance sheet in accordance with Accounting Standards Codification 210-20-45-1 up to April 30, 2020. In preparation for the STAR IPO, ACM Shanghai was required to terminate its financial relationship with SMC. In order to facilitate such termination, on April 30, 2020, ACM entered into two agreements relating to outstanding obligations among ACM Research, ACM Shanghai and SMC. Pursuant to such agreements: (i) ACM Shanghai assigned to ACM its rights under the SMC Note, including the right to receive payment of the $1,820 payable thereunder; (ii) ACM cancelled the outstanding $1,820 obligation of ACM Shanghai under the Intercompany Note; (iii) SMC surrendered its remaining 242,681 Warrant shares to ACM Research; and (iv) in exchange for such 242,681 Warrant shares, ACM agreed to deliver to SMC certain consideration (“SMC Consideration”) agreed upon by ACM Research and SMC, subject to obtaining certain PRC regulatory approvals. Under the agreements, if the required approvals were not obtained by December 31, 2023, ACM would cancel the SMC Note as consideration for the 242,681 Warrant shares. In a separate transaction in April 2020, ACM Shanghai repaid the remaining $1,820 of the SMC Investment in cash. For the period beginning April 30, 2020 the SMC Consideration is accounted for as a financial liability, and the Company applies fair value option to measure the SMC Consideration in accordance with Accounting Standards Codification 825-15-4a. On April 30, 2020, the SMC Consideration was $9,715. The financial liability was remeasured to fair value as of the end of each of the reporting periods. On July 29, 2020 ACM and SMC entered into an amended agreement under which, in settlement of the SMC Consideration, ACM issued to SMC a warrant (the “SMC 2020 Warrant”) to purchase 242,681 shares of Class A common stock at a purchase price of $7.50 per share, and ACM cancelled the SMC Note. The financial liability was remeasured to fair value of $21,679 as of July 29, 2020, and was retired with the issuance of the SMC 2020 Warrant. The Company recognized a change in fair value of financial liability of $6,533 and $11,964 for the three and nine months ended September 30, 2020, respectively, which was charged to the consolidated statement of operations. The SMC 2020 Warrant was initially measured at fair value at the issuance date and classified as equity permanently in accordance with Accounting Standards Codification 815. The fair value of the SMC 2020 Warrant amounted to $21,679 based on the grant date using the Black-Scholes valuation model with the following assumptions: Nine Months Ended September 30, 2020 Fair value of common share(1) $89.28 Expected term in years(2) 3.42 Volatility(3) 47.42% Risk-free interest rate(4) 0.15% Expected dividend(5) 0% (1) Fair value of Class A common stock was the closing market price of the Class A common stock on July 29, 2020. (2) Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110. (3) Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant. (4) Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant. (5) Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock.

RELATED PARTY BALANCES AND TRAN

RELATED PARTY BALANCES AND TRANSACTIONS	9 Months Ended
	Sep. 30, 2020
RELATED PARTY BALANCES AND TRANSACTIONS [Abstract]
RELATED PARTY BALANCES AND TRANSACTIONS	NOTE 13 – RELATED PARTY BALANCES AND TRANSACTIONS Prepaid expenses September 30, 2020 December 31, 2019 Ninebell $ 2,272 $ 348 Accounts payable September 30, 2020 December 31, 2019 Ninebell $ 3,197 $ 727 Shengyi 609 488 Total $ 3,806 $ 1,215 Three Months Ended Nine Months Ended Purchase of materials 2020 2019 2020 2019 Ninebell $ 4,029 $ 2,591 $ 9,552 $ 7,395 Shengyi 599 261 1,113 453 Total $ 4,628 $ 2,852 $ 10,665 $ 7,848 Three Months Ended September 30 Nine Months Ended September 30 Service fee charged by 2020 2019 2020 2019 Shengyi $ 14 $ - $ 204 $ - Ninebell 22 - 22 - Total $ 36 $ - $ 226 $ -

COMMON STOCK

COMMON STOCK	9 Months Ended
	Sep. 30, 2020
COMMON STOCK [Abstract]
COMMON STOCK	NOTE 14 – COMMON STOCK ACM is authorized to issue 50,000,000 shares of Class A common stock and 2,409,738 shares of Class B common stock, each with a par value of $0.0001. Each share of Class A common stock is entitled to one vote, and each share of Class B common stock is entitled to twenty votes and is convertible at any time into one share of Class A common stock. Shares of Class A common stock and Class B common stock are treated equally, identically and ratably with respect to any dividends declared by the Board of Directors unless the Board of Directors declares different dividends to the Class A common stock and Class B common stock by getting approval from a majority of common stockholders. During the nine months ended September 30, 2020 and 2019, ACM issued 592,946 and 193,642 shares of Class A common stock upon option exercises by employees and non-employees, respectively. During the nine months ended September 30, 2020, ACM issued 64,717 shares of Class A common stock upon a cashless warrant exercise by a non-employee. During the three months ended September 30, 2020 and 2019, ACM issued and shares, respectively, of Class A common stock upon option exercises by employees and non-employees. During the nine months ended September 30, 2020, S MC transferred and cancelled its ownership of There were issued and outstanding 16,657,135 shares of Class A common stock and 1,802,606 shares of Class B common stock at September 30, 2020 and 16,182,151 shares of Class A common stock and 1,862,608 shares of Class B common stock at December 31, 2019.

REDEEMABLE NON-CONTROLLING INTE

REDEEMABLE NON-CONTROLLING INTERESTS	9 Months Ended
	Sep. 30, 2020
REDEEMABLE NON-CONTROLLING INTERESTS [Abstract]
REDEEMABLE NON-CONTROLLING INTERESTS	NOTE 15 – REDEEMABLE NON-CONTROLLING INTERESTS The components of the change in redeemable non-controlling interests for the nine months ended September 30, 2020 are presented in the following table: Balance at December 31, 2019 $ 60,162 Net income attributable to redeemable non-controlling interests 643 Effect of foreign currency translation gain attributable to redeemable non-controlling interests (847 ) Reclassification of redeemable non-controlling interest (59,958 ) Balance at September 30, 2020 $ - Upon the submission of application documents by ACM Shanghai for the STAR Listing and the STAR IPO to the Shanghai Stock Exchange during the second quarter of 2020, the redemption feature of the private placement funding (Note 1) terminated and the aggregate proceeds of the funding therefore were reclassified from redeemable non-controlling interests to non-controlling interests. Further, upon the termination of such redemption feature, the Company released the aggregate proceeds of the private placement funding from reserved cash, which the Company previously had voluntarily imposed in light of a potential redemption.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2020
STOCK-BASED COMPENSATION [Abstract]
STOCK-BASED COMPENSATION	NOTE 16 – STOCK-BASED COMPENSATION In January 2020 ACM Shanghai adopted a 2019 Stock Option Incentive Plan (the “Subsidiary Stock Option Plan”) that provides for, among other incentives, the granting to officers, directors, employees of options to purchase shares of ACM Shanghai’s common stock. The fair value of the stock options granted is estimated at the date of grant based on the Black-Scholes option pricing model using assumptions generally consistent with those used for ACM’s stock options. Because ACM Shanghai shares are not currently publicly traded, the expected volatility is estimated with reference to the average historical volatility of a group of publicly traded companies that are believed to have similar characteristics to ACM Shanghai. ACM’s stock-based compensation consists of employee and non-employee awards issued under the 1998 Stock Option Plan and the 2016 Omnibus Incentive Plan and as standalone options. ACM granted stock options to employees under the 2016 Omnibus Incentive Plan during the nine months ended September 30, 2020. The vesting condition may consist of service period determined by the Board of Directors for s grant or certain performance conditions determined by the Board of Directors for a grant. The fair value of the stock options granted with service period based condition is estimated at the date of grant using the Black-Scholes option pricing model. The fair value of the stock options granted with market based condition is estimated at the date of grant using the Monte Carlo simulation model. The following table summarizes the components of stock-based compensation expense included in the consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Stock-Based Compensation Expense: Cost of revenue $ 44 $ 154 $ 132 $ 213 Sales and marketing expense 237 172 495 252 Research and development expense 193 759 568 939 General and administrative expense 2,305 472 3,128 1,515 $ 2,779 $ 1,557 $ 4,323 $ 2,919 Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Stock-based compensation expense by type: Employee stock purchase plan $ 2,651 $ 1,329 $ 3,717 $ 1,841 Non-employee stock purchase plan 44 228 356 1,078 Subsidiary option grants 84 - 250 - $ 2,779 $ 1,557 $ 4,323 $ 2,919 Employee Awards The following table summarizes the Company’s employee share option activities during the nine months ended September 30, 2020: Number of Option Share Weighted Average Grant Date Fair Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term Outstanding at December 31, 2019 2,994,063 $ 2.59 $ 6.77 7.05 years Granted 778,399 11.98 28.70 Exercised (327,917 ) 1.56 4.33 Expired - - - Forfeited/cancelled (40,515 ) 4.94 13.04 Outstanding at September 30, 2020 3,404,030 $ 4.81 $ 11.95 7.14 years Vested and exercisable at September 30, 2020 2,061,793 As of September 30, 2020 and December 31, 2019, $ and $ , respectively, of total unrecognized employee stock-based compensation expense, net of estimated forfeitures, related to stock-based awards for ACM were expected to be recognized over a weighted-average period of years and years, respectively. Total recognized compensation cost may be adjusted for future changes in estimated forfeitures. Non-employee Awards The following table summarizes ACM’s non-employee stock option activities during the nine months ended September 30, 2020: Number of Option Shares Weighted Average Grant Date Fair Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term Outstanding at December 31, 2019 1,101,613 $ 0.82 $ 2.69 5.85 years Granted 20,000 10.29 25.60 Exercised (265,029 ) 0.91 3.34 Expired - Forfeited/cancelled (111 ) 0.30 0.75 Outstanding at September 30, 2020 856,473 $ 1.01 $ 3.02 5.11 years Vested and exercisable at September 30, 2020 819,819 As of September 30, 2020 and December 31, 2019, $ and $ , respectively, of total unrecognized non-employee stock-based compensation expense, net of estimated forfeitures, related to stock-based awards were expected to be recognized over a weighted-average period of years and years, respectively. Total recognized compensation cost may be adjusted for future changes in estimated forfeitures. The fair value of options granted to employee and non-employee with a is estimated on the grant date using the Black-Scholes valuation model with the following assumptions. Nine Months Ended September 30, Year Ended December 31, 2020 2019 Fair value of common share(1) $22.07-85.27 $13.64-16.81 Expected term in years(2) 5.50-6.25 6.25 Volatility(3) 42.17%-48.15% 39.91%-40.35% Risk-free interest rate(4) 0.27%-0.82% 1.69%-2.46% Expected dividend(5) 0% 0% (1) Fair value of Class A common stock value was the closing market price of the Class A common stock on the grant date. (2) Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110. (3) Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant. (4) Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant. (5) Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock. The fair value of option granted to employee with is estimated on the grant date using the Monte Carlo simulation model with the following assumptions. Nine Months Ended September 30 , 2020 Fair value of common share(1) $ Expected term in years(2) 9.20 - Volatility(3) 45.10% Risk-free interest rate(4) 2.68% Expected dividend(5) 0% (1) Fair value of Class A common stock value was the closing market price of the Class A common stock on the grant date. (2) Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110. (3) Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant. (4) Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant. (5) Expected dividend is assumed to be as ACM has no history or expectation of paying a dividend on its common stock. ACM Shanghai Option Grants The following table summarizes the ACM Shanghai employee stock option activities during the nine months ended September 30, 2020: Number of Option Shares in ACM Shanghai Weighted Average Grant Date Fair Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term Outstanding at December 31, 2019 - $ - $ - - Granted 5,869,808 0.22 1.87 Exercised - - - Expired - - - Forfeited/cancelled (330,770 ) 0.23 1.87 Outstanding at September 30, 2020 5,539,038 $ 0.22 $ 1.87 3.76 years Vested and exercisable at September 30, 2020 - During the three and nine months ended September 30, 2020, As of September 30, 2020, $ of total unrecognized non-employee stock-based compensation expense, net of estimated forfeitures, related to ACM Shanghai stock-based awards were expected to be recognized over a weighted-average period of years. Total recognized compensation cost may be adjusted for future changes in estimated forfeitures.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2020
INCOME TAXES [Abstract]
INCOME TAXES	NOTE 17 – INCOME TAXES Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry-forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period during which such rates are enacted. The Company considers all available evidence to determine whether it is more likely than not that some portion or all of the deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become realizable. Management considers the scheduled reversal of deferred tax liabilities (including the impact of available carryback and carry-forward periods) and projected taxable income in assessing the realizability of deferred tax assets. In making such judgments, significant weight is given to evidence that can be objectively verified. As of each reporting date, management considers new evidence, both positive and negative, that could affect its view of the future realization of deferred tax assets. Prior to September 30, 2019, the Company had recorded a valuation allowance for the full amount of net deferred tax assets in the United States, as the realization of deferred tax assets was uncertain. Since September 30, 2019, the Company has not maintained a valuation allowance except for a partial valuation allowance on certain U.S. deferred tax assets. In order to recognize the remaining U.S. deferred tax assets that continue to be subject to a valuation allowance, the Company will need to generate sufficient U.S. taxable income in future periods before the expiration of the deferred tax assets governed by the tax code. ACM Shanghai has shown a three-year historical cumulative profit and has projections of future income. As a result, the Company does not maintain a valuation allowance. The Company accounts for uncertain tax positions in accordance with the authoritative guidance on income taxes under which the Company may only recognize or continue to recognize tax positions that meet a more likely than not threshold. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as a component of the provision for income taxes. The Company’s effective tax rate differs from statutory rates of 21% for U.S. federal income tax purposes and 15% to 25% for Chinese income tax purposes due to the effects of the valuation allowance and certain permanent differences from book-tax differences. As a result, the Company recorded income tax benefit (expense) of $1,747 and $328 during the three months ended September 30, 2020 and 2019, respectively, and $ and $ during the nine months ended September 30, 2020 and 2019, respectively. As of September 30, 2020, the Company’s total unrecognized tax benefits were $155, which would not affect the effective tax rate if recognized. The Company will recognize interest and penalties, when they occur, related to uncertain tax provisions as a component of tax expense. No interest or penalties were recognized for the nine months ended September 30, 2020. The Company files income tax returns in the United States and state and foreign jurisdictions. The federal, state and foreign income tax returns are under the statute of limitations subject to tax examinations for the tax years ended December 31, 2009 through December 31, 2019. To the extent the Company has tax attribute carry-forwards, the tax years in which the attribute was generated may still be adjusted upon examination by the U.S. Internal Revenue Service, state or foreign tax authorities to the extent utilized in a future period. The Company’s effective tax rate differs from statutory rates of for U.S. federal income tax purposes and to for Chinese income tax purposes due to the effects of the valuation allowance and certain permanent differences as it pertains to book-tax differences in the value of client equity securities received for services and the treatment of stock-based compensation. The Company’s PRC subsidiaries, ACM Shanghai, ACM Wuxi and ACM Shengwei, are liable for PRC corporate income taxes at the rates of , and respectively. Pursuant to the Corporate Income Tax Law of the PRC, ACM’s PRC subsidiaries generally would be liable for PRC corporate income taxes as a rate of . According to Guoshuihan No. an entity certified as an “advanced and new technology enterprise” is entitled to a preferential income tax rate of . ACM Shanghai was certified as an “advanced and new technology enterprise” in and again in and with an effective period of . ACM files income tax returns in the United States and state and foreign jurisdictions. Those federal, state and foreign income tax returns are under the statute of limitations subject to tax examinations for 2009 through 2019. To the extent ACM has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the U.S. Internal Revenue Service or state or foreign tax authorities to the extent utilized in a future period. The U.S. Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was enacted on March 27, 2020. It contains several provisions that may have financial statement effects. Key aspects of the CARES Act include the following: • repealed the 80% taxable income limitation for 2018, 2019 and 2020, and allows those years to be carried back up to five years; • allows corporations to claim 100% of AMT credits in 2019, and provides for an election to take the entire refundable credit amount in 2018; • raised the Section 163(j) ATI limit from 30% to 50% for businesses; and • made technical corrections to TCJA for Qualified Improvement Property (“QIP”) and designates QIP as 15-year property for depreciation purposes, which makes QIP a category eligible for 100% bonus depreciation The CARES Act is not expected to have a material impact on income taxes in the Company’s consolidated financial statements. Income tax expense was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) Total income tax benefit (expense) $ 1,747 $ 328 $ (416 ) $ (667 )

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2020
COMMITMENTS AND CONTINGENCIES [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 18 – COMMITMENTS AND CONTINGENCIES The Company leases offices under non-cancelable operating lease agreements. See note for future minimum lease payments under non-cancelable operating lease agreements with initial terms of year or more. As of September the Company had of open capital commitments. Covenants in ACM Shengwei’s Grant Contract for State-owned Construction Land Use Right in Shanghai City, with the China (Shanghai) Pilot Free Trade Zone Lin-gang Special Area Administration require, among other things, that ACM Shengwei pay liquidated damages in the event that (a) it does not make a total investment (including the costs of construction, fixtures, equipment and grant fees) of at least RMB 450.0 million ($63,400) or (b) within six years after the land use right is obtained, the Company does not (i) generate a minimum specified amount of annual sales of products manufactured on the granted land or (ii) pay to the PRC at least RMB 157.6 million ($22,000) in annual total taxes (including value-added taxes, corporate income tax, personal income taxes, urban maintenance and construction taxes, education surcharges, stamp taxes, and vehicle and shipping taxes) as a result of operations in connection with the granted land. From time to time the Company is subject to legal proceedings, including claims in the ordinary course of business and claims with respect to patent infringements. As of September 30, 2020, the Company did not have any legal proceedings.

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2020
SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The Company’s consolidated financial statements include the accounts of ACM and its subsidiaries, including ACM Shanghai and its subsidiaries, which include ACM Wuxi, ACM Shengwei and CleanChip (the subsidiaries of which include ACM California and ACM Korea). ACM’s subsidiaries are those entities in which ACM, directly and indirectly, controls more than one half of the voting power. All significant intercompany transactions and balances have been eliminated upon consolidation. The accompanying condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and the rules and regulations of the Securities and Exchange Commission for reporting on Form 10-Q. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. The unaudited condensed consolidated financial statements herein should be read in conjunction with the historical consolidated financial statements of the Company for the year ended December 31, 2019 included in ACM’s Annual Report on Form 10-K for the year ended December 31, 2019. The accompanying condensed consolidated balance sheet as of September 30, 2020, condensed consolidated statements of operations and comprehensive income for the three and nine months ended September 30, 2020 and 2019, condensed consolidated statements of changes in stockholders’ equity for the three and nine months ended September 30, 2020 and 2019, and condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019 are unaudited. In the opinion of management, the unaudited condensed consolidated financial statements of the Company reflect all adjustments that are necessary for a fair presentation of the Company’s financial position and results of operations. Such adjustments are of a normal recurring nature, unless otherwise noted. The balance sheet as of September 30, 2020 and the results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results to be expected for
COVID-19 Assessment	COVID-19 Assessment The outbreak of COVID-19, the coronavirus, has grown both in the United States and globally, and related government and private sector responsive actions have adversely affected the Company’s business operations. In December 2019 a series of emergency quarantine measures taken by the PRC government disrupted domestic business activities during the weeks after the initial outbreak of COVID-19. Since that time, an increasing number of countries, including the United States, have imposed restrictions on travel to and from the PRC and elsewhere, as well as general movement restrictions, business closures and other measures imposed to slow the spread of COVID-19. The situation continues to develop, however, and it is impossible to predict the effect and ultimate impact of the COVID-19 outbreak on the Company’s business operations and results. While the quarantine, social distancing and other regulatory measures instituted or recommended in response to COVID-19 are expected to be temporary, the duration of the business disruptions, and related financial impact, cannot be estimated at this time. The COVID-19 outbreak has been declared a worldwide health pandemic that could adversely affect the economies and financial markets of many countries, resulting in an economic downturn and changes in global economic policy that could reduce demand for the Company’s products and its customers’ chips and have a material adverse impact on the Company’s business, operating results and financial condition. Through September
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the balance sheet date and the reported revenue and expenses during the reported period in the condensed consolidated financial statements and accompanying notes. The Company’s significant accounting estimates and assumptions include, but are not limited to, those used for the valuation and recognition of stock-based compensation arrangements and valuation of financial liability, realization of deferred tax assets, assessment for impairment of long-lived assets, allowance for doubtful accounts, inventory valuation for excess and obsolete inventories, lower of cost and market value or net realizable value of inventories, depreciable lives of property and equipment, and useful life of intangible assets. Management believes that the estimates, judgments and assumptions are reasonable, based on information available at the time they are made. Actual results could differ materially from those estimates.
Basic and Diluted Net Income per Common Share	Basic and Diluted Net Income per Common Share Basic and diluted net income per common share is calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net income $ 10,020 $ 9,089 $ 12,479 $ 15,257 Net income attributable to non-controlling interests and redeemable non-controlling interests 1,393 307 2,228 307 Net income available to common stockholders, basic and diluted $ 8,627 $ 8,782 $ 10,251 $ 14,950 Weighted average shares outstanding, basic 18,201,943 16,999,746 18,124,665 16,381,944 Effect of dilutive securities 3,353,353 2,354,468 3,132,996 2,317,066 Weighted average shares outstanding, diluted 21,555,296 19,354,214 21,257,661 18,699,010 Net income per common share: Basic $ 0.47 $ 0.52 $ 0.57 $ 0.91 Diluted $ 0.40 $ 0.45 $ 0.48 $ 0.80 ACM has been authorized to issue Class A and Class B common stock since redomesticating in Delaware in November 2016. The two classes of common stock are substantially identical in all material respects, except for voting rights. Since ACM did not declare any dividends during the three and nine months ended September Diluted net income per common share reflects the potential dilution from securities that could share in ACM’s earnings. ACM’s potential dilutive securities consist of warrants and stock options for the three and nine months ended September
Land Use Rights, Net	Land use right, net The land use right represents the cost to purchase a right to use state-owned land in the PRC with lease terms of years The land use right is carried at cost less accumulated amortization and impairment losses, if any. Amortization is computed using the straight-line method over the term specified in the land use right certificate, which is years.
Concentration of Credit Risk	Concentration of Credit Risk The Company is potentially subject to concentrations of credit risks in its accounts receivable. For the nine months ended September September September
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In August 2018, the Financial Accounting Standards Board Fair Value Measurement (Topic 820) Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815) and Leases (Topic 842), In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes

DESCRIPTION OF BUSINESS (Tables

DESCRIPTION OF BUSINESS (Tables)	9 Months Ended
	Sep. 30, 2020
DESCRIPTION OF BUSINESS [Abstract]
Direct or Indirect Interests of Subsidiaries	The Company has direct or indirect interests in the following subsidiaries: Effective interest held as at Name of subsidiaries Place and date of incorporation September 30, 2020 December 31, 2019 ACM Research (Shanghai), Inc. China, May 2005 91.7 % 91.7 % ACM Research (Wuxi), Inc. China, July 2011 91.7 % 91.7 % CleanChip Technologies Limited Hong Kong, June 2017 91.7 % 91.7 % ACM Research Korea CO., LTD. Korea, December 2017 91.7 % 91.7 % Shengwei Research (Shanghai), Inc. China, March 2019 91.7 % 91.7 % ACM Research (CA), Inc. USA, June 2019 91.7 % 91.7 % ACM Research (Cayman), Inc. Cayman Islands, April 2019 100.0 % 100.0 %

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Sep. 30, 2020
SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Basic and Diluted Net Income per Common Share	Basic and diluted net income per common share is calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net income $ 10,020 $ 9,089 $ 12,479 $ 15,257 Net income attributable to non-controlling interests and redeemable non-controlling interests 1,393 307 2,228 307 Net income available to common stockholders, basic and diluted $ 8,627 $ 8,782 $ 10,251 $ 14,950 Weighted average shares outstanding, basic 18,201,943 16,999,746 18,124,665 16,381,944 Effect of dilutive securities 3,353,353 2,354,468 3,132,996 2,317,066 Weighted average shares outstanding, diluted 21,555,296 19,354,214 21,257,661 18,699,010 Net income per common share: Basic $ 0.47 $ 0.52 $ 0.57 $ 0.91 Diluted $ 0.40 $ 0.45 $ 0.48 $ 0.80

ACCOUNTS RECEIVABLE (Tables)

ACCOUNTS RECEIVABLE (Tables)	9 Months Ended
	Sep. 30, 2020
ACCOUNTS RECEIVABLE [Abstract]
Accounts Receivable	At September September 30, 2020 December 31, 2019 Accounts receivable $ 59,796 $ 31,091 Less: Allowance for doubtful accounts - - Total $ 59,796 $ 31,091

INVENTORIES (Tables)

INVENTORIES (Tables)	9 Months Ended
	Sep. 30, 2020
INVENTORIES [Abstract]
Inventory	At September September 30, 2020 December 31, 2019 Raw materials $ 27,254 $ 15,105 Work in process 13,882 10,407 Finished goods 23,046 19,284 Total inventory $ 64,182 $ 44,796

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT, NET (Tables)	9 Months Ended
	Sep. 30, 2020
PROPERTY, PLANT AND EQUIPMENT, NET [Abstract]
Property, Plant and Equipment	At September September 30, 2020 December 31, 2019 Manufacturing equipment $ 4,093 $ 3,902 Office equipment 926 627 Transportation equipment 177 124 Leasehold improvement 1,471 1,442 Total cost 6,667 6,095 Less: Total accumulated depreciation (3,751 ) (3,077 ) Construction in progress 3,058 601 Total property, plant and equipment, net $ 5,974 $ 3,619

SHORT-TERM BORROWINGS (Tables)

SHORT-TERM BORROWINGS (Tables)	9 Months Ended
	Sep. 30, 2020
SHORT-TERM BORROWINGS [Abstract]
Short-Term Borrowings	At September 30, 2020 and December 31, 2019, short-term borrowings consisted of the following: September 30, 2020 December 31, 2019 Line of credit up to RMB 50,000 from Bank of Shanghai Pudong Branch, due on January 23, 2020 with an annual interest rate of 5.22%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. It was fully repaid on January 23, 2020. $ - $ 5,057 Line of credit up to RMB 20,000 from Shanghai Rural Commercial Bank, due on February 21, 2020 with an annual interest rate of 5.66%, guaranteed by the Company’s CEO and pledged by accounts receivable. It was fully repaid on February 21, 2020. - 1,433 Line of credit up to RMB 20,000 from Bank of Communications, due on January 18, 2020 with an annual interest rate of 5.66% and fully repaid on January 19, 2020. - 1,433 Line of credit up to RMB 20,000 from Bank of Communications, due on January 22, 2020 with an annual interest rate of 5.66% and fully repaid on January 22, 2020. - 717 Line of credit up to RMB 20,000 from Bank of Communications, due on February 14, 2020 with an annual interest rate of 5.66% and fully repaid on February 14, 2020. - 717 Line of credit up to RMB 50,000 from China Everbright Bank, due on March 25, 2020 with an annual interest rate of 4.94%, guaranteed by the Company’s CEO and fully repaid on March 24, 2020. - 3,250 Line of credit up to RMB 50,000 from China Everbright Bank, due on April 17, 2020 with an annual interest rate of 5.66%, guaranteed by the Company’s CEO and fully repaid on April 2, 2020. - 1,146 Line of credit up to RMB 80,000 from China Everbright Bank, due on April 1, 2021 with an annual interest rate of 4.70%, guaranteed by the Company’s CEO. 4,404 - Line of credit up to RMB 80,000 from China Everbright Bank, due on June 27, 2021 with an annual interest rate of 4.25%, guaranteed by the Company’s CEO. 1,321 - Line of credit up to RMB 80,000 from China Everbright Bank, due on April 29, 2021 with an annual interest rate of 2.80%, guaranteed by the Company’s CEO. 820 - Line of credit up to RMB 80,000 from China Everbright Bank, due on June 27, 2021 with an annual interest rate of 2.70%, guaranteed by the Company’s CEO. 2,079 - Line of credit up to RMB 20,000 from Bank of Communications, due on April 12, 2021 with an annual interest rate of 4.65%. 1,468 - Line of credit up to RMB 20,000 from Bank of Communications, due on May 24, 2021 with an annual interest rate of 3.65%. 1,468 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on May 27, 2021 with an annual interest rate of 4.68%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 2,466 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on June 27, 2021 with an annual interest rate of 4.68%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 1,321 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on May 28, 2021 with an annual interest rate of 3.48%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 2,441 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on June 7, 2021 with an annual interest rate of 3.50%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 1,521 - Line of credit up to RMB 70,000 from Bank of Shanghai Pudong Branch, due on June 16, 2021 with an annual interest rate of 3.50%, guaranteed by the Company’s CEO and Cleanchip Technologies Limited. 1,837 - Line of credit up to RMB 30,000 from Bank of China Pudong Branch, due on December 17, 2020 with annual interest rate of 4.35%, guaranteed by the Company’s CEO. 2,496 - Line of credit up to RMB 80,000 from China Merchants Bank,due on August 10, 2021 with annual interest rate of 3.85%. 1,321 - Line of credit up to RMB 80,000 from China Merchants Bank,due on August 25, 2021 with annual interest rate of 3.85%. 2,936 - Line of credit up to KRW 500,000 from Industrial Bank of Korea, due on July 11, 2021 with an annual interest rate of 3.99%,guaranteed by the ACM-KOREA CEO. 428 - Total $ 28,327 $ 13,753

OTHER PAYABLE AND ACCRUED EXP_2

OTHER PAYABLE AND ACCRUED EXPENSES (Tables)	9 Months Ended
	Sep. 30, 2020
OTHER PAYABLE AND ACCRUED EXPENSES [Abstract]
Other Payable and Accrued Expenses	At September September 30, 2020 December 31, 2019 Accrued commissions $ 7,785 $ 4,082 Accrued warranty 3,449 2,811 Accrued payroll 2,960 2,092 Accrued professional fees 40 165 Accrued machine testing fees 1,481 1,456 Others 2,779 2,268 Total $ 18,494 $ 12,874

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Sep. 30, 2020
LEASES [Abstract]
Components of Lease Expense	The components of lease expense were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Operating lease cost $ 384 $ 363 $ 1,139 $ 1,064 Short-term lease cost 73 92 170 117 Lease cost $ 457 $ 455 $ 1,309 $ 1,181
Supplemental Cash Flow Information Related to Operating Leases	Supplemental cash flow information related to operating leases was as follows for the three and nine-month periods ended September 30, 2020 Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash outflow from operating leases $ 457 $ 455 $ 1,309 $ 1,181
Maturities of Lease Liabilities for Operating Leases	Maturities of lease liabilities for all operating leases were as follows as of September 30, 2020 December 31, 2020 $ 390 2021 1,592 2022 1,580 2023 912 2024 872 2025 22 Total lease payments 5,368 Less: Interest (800 ) Present value of lease liabilities $ 4,568
Weighted Average Remaining Lease Terms and Discount Rates for Operating Leases	The weighted average remaining lease terms and discount rates for all operating leases were as follows as of September 30, 2020 and December 31, 2019 September 30, 2020 December 31, 2019 Remaining lease term and discount rate: Weighted average remaining lease term (years) 3.70 3.02 Weighted average discount rate 5.29 % 5.43 %

OTHER LONG-TERM LIABILITIES (Ta

OTHER LONG-TERM LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2020
OTHER LONG-TERM LIABILITIES [Abstract]
Other Long-Term Liabilities	Other long-term liabilities represent subsidies that we have received from governmental authorities, including China’s Ministry of Science and Technology, the Shanghai Municipal Commission of Economy and Information, and the Shanghai Science and Technology Committee, for development and commercialization of certain technology but have not yet earned and recognized. As of September 30, 2020 and December 31, 2019, other long-term liabilities consisted of the following unearned government subsidies: September 30, 2020 December 31, 2019 Subsidies to Stress Free Polishing project, commenced in 2008 and 2017 $ 1,126 $ 1,251 Subsidies to Electro Copper Plating project, commenced in 2014 2,188 2,666 Subsidies to Polytetrafluoroethylene, commenced in 2018 125 135 Subsidies to Tahoe-Single Bench Clean, commenced in 2020 1,962 - Subsidies to Backside Clean-YMTC National Project, commenced in 2020 751 - Other 302 134 Total $ 6,454 $ 4,186

LONG TERM INVESTMENTS (Tables)

LONG TERM INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2020
LONG TERM INVESTMENTS [Abstract]
Components of Long-Term Investment	The components of long-term investments were as follows: September 30, 2020 December 31, 2019 Ninebell $ 2,088 $ 1,538 Shengyi 134 107 Hefei Shixi 4,358 4,289 Total $ 6,580 $ 5,934

TRADING SECURITIES (Tables)

TRADING SECURITIES (Tables)	9 Months Ended
	Sep. 30, 2020
TRADING SECURITIES [Abstract]
Components of Trading Securities	The components of trading securities were as follows: September 30, 2020 December 31, 2019 Trading securities listed in Shanghai Stock Exchange Cost $ 14,680 $ - Market value $ 23,888 $ -

FINANCIAL LIABILITY CARRIED A_2

FINANCIAL LIABILITY CARRIED AT FAIR VALUE (Tables)	9 Months Ended
	Sep. 30, 2020
FINANCIAL LIABILITY CARRIED AT FAIR VALUE [Abstract]
Assumptions Used to Determine Fair Value of Warrants	The SMC 2020 Warrant was initially measured at fair value at the issuance date and classified as equity permanently in accordance with Accounting Standards Codification 815. The fair value of the SMC 2020 Warrant amounted to $21,679 based on the grant date using the Black-Scholes valuation model with the following assumptions: Nine Months Ended September 30, 2020 Fair value of common share(1) $89.28 Expected term in years(2) 3.42 Volatility(3) 47.42% Risk-free interest rate(4) 0.15% Expected dividend(5) 0% (1) Fair value of Class A common stock was the closing market price of the Class A common stock on July 29, 2020. (2) Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110. (3) Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant. (4) Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant. (5) Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock.

RELATED PARTY BALANCES AND TR_2

RELATED PARTY BALANCES AND TRANSACTIONS (Tables)	9 Months Ended
	Sep. 30, 2020
RELATED PARTY BALANCES AND TRANSACTIONS [Abstract]
Related Party Balances and Transactions	Prepaid expenses September 30, 2020 December 31, 2019 Ninebell $ 2,272 $ 348 Accounts payable September 30, 2020 December 31, 2019 Ninebell $ 3,197 $ 727 Shengyi 609 488 Total $ 3,806 $ 1,215 Three Months Ended Nine Months Ended Purchase of materials 2020 2019 2020 2019 Ninebell $ 4,029 $ 2,591 $ 9,552 $ 7,395 Shengyi 599 261 1,113 453 Total $ 4,628 $ 2,852 $ 10,665 $ 7,848 Three Months Ended September 30 Nine Months Ended September 30 Service fee charged by 2020 2019 2020 2019 Shengyi $ 14 $ - $ 204 $ - Ninebell 22 - 22 - Total $ 36 $ - $ 226 $ -

REDEEMABLE NON-CONTROLLING IN_2

REDEEMABLE NON-CONTROLLING INTERESTS (Tables)	9 Months Ended
	Sep. 30, 2020
REDEEMABLE NON-CONTROLLING INTERESTS [Abstract]
Components of Change in Redeemable Non-controlling Interests	The components of the change in redeemable non-controlling interests for the nine months ended September 30, 2020 are presented in the following table: Balance at December 31, 2019 $ 60,162 Net income attributable to redeemable non-controlling interests 643 Effect of foreign currency translation gain attributable to redeemable non-controlling interests (847 ) Reclassification of redeemable non-controlling interest (59,958 ) Balance at September 30, 2020 $ -

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2020
Stock-Based Compensation [Abstract]
Components of Stock-based Compensation Expense	The following table summarizes the components of stock-based compensation expense included in the consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Stock-Based Compensation Expense: Cost of revenue $ 44 $ 154 $ 132 $ 213 Sales and marketing expense 237 172 495 252 Research and development expense 193 759 568 939 General and administrative expense 2,305 472 3,128 1,515 $ 2,779 $ 1,557 $ 4,323 $ 2,919 Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Stock-based compensation expense by type: Employee stock purchase plan $ 2,651 $ 1,329 $ 3,717 $ 1,841 Non-employee stock purchase plan 44 228 356 1,078 Subsidiary option grants 84 - 250 - $ 2,779 $ 1,557 $ 4,323 $ 2,919
Assumptions Used to Determine Fair Value of Share Options Granted	The fair value of options granted to employee and non-employee with a is estimated on the grant date using the Black-Scholes valuation model with the following assumptions. Nine Months Ended September 30, Year Ended December 31, 2020 2019 Fair value of common share(1) $22.07-85.27 $13.64-16.81 Expected term in years(2) 5.50-6.25 6.25 Volatility(3) 42.17%-48.15% 39.91%-40.35% Risk-free interest rate(4) 0.27%-0.82% 1.69%-2.46% Expected dividend(5) 0% 0% (1) Fair value of Class A common stock value was the closing market price of the Class A common stock on the grant date. (2) Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110. (3) Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant. (4) Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant. (5) Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock. The fair value of option granted to employee with is estimated on the grant date using the Monte Carlo simulation model with the following assumptions. Nine Months Ended September 30 , 2020 Fair value of common share(1) $ Expected term in years(2) 9.20 - Volatility(3) 45.10% Risk-free interest rate(4) 2.68% Expected dividend(5) 0% (1) Fair value of Class A common stock value was the closing market price of the Class A common stock on the grant date. (2) Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110. (3) Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant. (4) Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant. (5) Expected dividend is assumed to be as ACM has no history or expectation of paying a dividend on its common stock.
Employee Share Option [Member]
Stock-Based Compensation [Abstract]
Summary of Share Option Activities	The following table summarizes the Company’s employee share option activities during the nine months ended September 30, 2020: Number of Option Share Weighted Average Grant Date Fair Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term Outstanding at December 31, 2019 2,994,063 $ 2.59 $ 6.77 7.05 years Granted 778,399 11.98 28.70 Exercised (327,917 ) 1.56 4.33 Expired - - - Forfeited/cancelled (40,515 ) 4.94 13.04 Outstanding at September 30, 2020 3,404,030 $ 4.81 $ 11.95 7.14 years Vested and exercisable at September 30, 2020 2,061,793
Employee Share Option [Member] | ACM Shanghai [Member]
Stock-Based Compensation [Abstract]
Summary of Share Option Activities	The following table summarizes the ACM Shanghai employee stock option activities during the nine months ended September 30, 2020: Number of Option Shares in ACM Shanghai Weighted Average Grant Date Fair Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term Outstanding at December 31, 2019 - $ - $ - - Granted 5,869,808 0.22 1.87 Exercised - - - Expired - - - Forfeited/cancelled (330,770 ) 0.23 1.87 Outstanding at September 30, 2020 5,539,038 $ 0.22 $ 1.87 3.76 years Vested and exercisable at September 30, 2020 -
Non-Employee Stock Option [Member]
Stock-Based Compensation [Abstract]
Summary of Share Option Activities	The following table summarizes ACM’s non-employee stock option activities during the nine months ended September 30, 2020: Number of Option Shares Weighted Average Grant Date Fair Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term Outstanding at December 31, 2019 1,101,613 $ 0.82 $ 2.69 5.85 years Granted 20,000 10.29 25.60 Exercised (265,029 ) 0.91 3.34 Expired - Forfeited/cancelled (111 ) 0.30 0.75 Outstanding at September 30, 2020 856,473 $ 1.01 $ 3.02 5.11 years Vested and exercisable at September 30, 2020 819,819

INCOME TAXES (Tables)

INCOME TAXES (Tables)	9 Months Ended
	Sep. 30, 2020
INCOME TAXES [Abstract]
Income Tax Expense	Income tax expense was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) Total income tax benefit (expense) $ 1,747 $ 328 $ (416 ) $ (667 )

DESCRIPTION OF BUSINESS (Detail

DESCRIPTION OF BUSINESS (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
ACM Research (Shanghai), Inc. [Member]
Description of Business [Abstract]
Purchase of equity interest percentage	8.30%
Name of subsidiaries	ACM Research (Shanghai), Inc.
Term to complete listing of shares	3 years
Date and place of Incorporation	China, May 2005
Effective interest held as at	91.70%	91.70%
ACM Research (Wuxi), Inc. [Member]
Description of Business [Abstract]
Name of subsidiaries	ACM Research (Wuxi), Inc.
Date and place of Incorporation	China, July 2011
Effective interest held as at	91.70%	91.70%
CleanChip Technologies Limited [Member]
Description of Business [Abstract]
Proceeds from sale of interest in subsidiary		$ 3,500
Name of subsidiaries	CleanChip Technologies Limited
Date and place of Incorporation	Hong Kong, June 2017
Effective interest held as at	91.70%	91.70%
ACM Research Korea CO., LTD [Member]
Description of Business [Abstract]
Name of subsidiaries	ACM Research Korea CO., LTD.
Date and place of Incorporation	Korea, December 2017
Effective interest held as at	91.70%	91.70%
Shengwei Research (Shanghai), Inc. [Member]
Description of Business [Abstract]
Purchase of equity interest percentage		91.70%
Name of subsidiaries	Shengwei Research (Shanghai), Inc.
Date and place of Incorporation	China, March 2019
Effective interest held as at	91.70%	91.70%
ACM Research (CA), Inc. [Member]
Description of Business [Abstract]
Name of subsidiaries	ACM Research (CA), Inc.
Date and place of Incorporation	USA, June 2019
Effective interest held as at	91.70%	91.70%
ACM Research (Cayman), Inc. [Member]
Description of Business [Abstract]
Name of subsidiaries	ACM Research (Cayman), Inc.
Date and place of Incorporation	Cayman Islands, April 2019
Effective interest held as at	100.00%	100.00%

SIGNIFICANT ACCOUNTING POLICI_4

SIGNIFICANT ACCOUNTING POLICIES, Basic and Diluted Net Income per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator [Abstract]
Net income	$ 10,020	$ 9,089	$ 12,479	$ 15,257
Net income attributable to non-controlling interests and redeemable non-controlling interests	1,393	307	2,228	307
Net income attributable to ACM Research, Inc.	$ 8,627	$ 8,782	$ 10,251	$ 14,950
Weighted average shares outstanding, basic (in shares)	18,201,943	16,999,746	18,124,665	16,381,944
Effect of dilutive securities (in shares)	3,353,353	2,354,468	3,132,996	2,317,066
Weighted average shares outstanding, diluted (in shares)	21,555,296	19,354,214	21,257,661	18,699,010
Net income per common share:
Basic (in dollars per share)	$ 0.47	$ 0.52	$ 0.57	$ 0.91
Diluted (in dollars per share)	$ 0.40	$ 0.45	$ 0.48	$ 0.80

SIGNIFICANT ACCOUNTING POLICI_5

SIGNIFICANT ACCOUNTING POLICIES, Land Use Rights, Net (Details)	9 Months Ended
	Sep. 30, 2020
SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Right to use land lease term	50 years

SIGNIFICANT ACCOUNTING POLICI_6

SIGNIFICANT ACCOUNTING POLICIES, Concentration of Credit Risk (Details) - Customer	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accounts Receivable [Member]
Concentration of Credit Risk [Abstract]
Number of major customers	3	3	3	3
Concentration of credit risk	72.10%	98.60%	79.80%	72.30%
Revenue Benchmark [Member]
Concentration of Credit Risk [Abstract]
Number of major customers	3	3
Concentration of credit risk	76.90%	67.70%

ACCOUNTS RECEIVABLE (Details)

ACCOUNTS RECEIVABLE (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts Receivable [Abstract]
Accounts receivable	$ 59,796	$ 31,091
Less: allowance for doubtful accounts	0	0
Total	59,796	31,091
Accounts receivable pledged as collateral for borrowings	$ 0	$ 1,433

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Inventory [Abstract]
Raw materials	$ 27,254	$ 15,105
Work in process	13,882	10,407
Finished goods	23,046	19,284
Total inventory	$ 64,182	$ 44,796

PROPERTY, PLANT AND EQUIPMENT_3

PROPERTY, PLANT AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Total cost	$ 6,667		$ 6,667		$ 6,095
Less: Total accumulated depreciation	(3,751)		(3,751)		(3,077)
Construction in progress	3,058		3,058		601
Total property, plant and equipment, net	5,974		5,974		3,619
Depreciation expense	195	$ 176	569	$ 528
Manufacturing Equipment [Member]
Property, Plant and Equipment [Abstract]
Total cost	4,093		4,093		3,902
Office Equipment [Member]
Property, Plant and Equipment [Abstract]
Total cost	926		926		627
Transportation Equipment [Member]
Property, Plant and Equipment [Abstract]
Total cost	177		177		124
Leasehold Improvement [Member]
Property, Plant and Equipment [Abstract]
Total cost	$ 1,471		$ 1,471		$ 1,442

SHORT-TERM BORROWINGS (Details)

SHORT-TERM BORROWINGS (Details) ₩ in Thousands, ¥ in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020CNY (¥)	Sep. 30, 2020KRW (₩)	Dec. 31, 2019USD ($)
Short-Term Borrowings [Abstract]
Short-term borrowings	$ 28,327		$ 28,327				$ 13,753
Interest expense related to short-term borrowings	272	$ 205	611	$ 538
Line of Credit Due on January 23, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				5,057
Maximum borrowing capacity | ¥					¥ 50,000
Annual interest rate			5.22%
Line of credit due date			Jan. 23, 2020
Line of Credit Due on February 21, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				1,433
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Feb. 21, 2020
Line of Credit Due on January 18, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				1,433
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Jan. 19, 2020
Line of Credit Due on January 22, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				717
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Jan. 22, 2020
Line of Credit Due on February 14, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				717
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Feb. 14, 2020
Line of Credit Due on March 25, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				3,250
Maximum borrowing capacity | ¥					50,000
Annual interest rate			4.94%
Line of credit due date			Mar. 24, 2020
Line of Credit Due on April 17, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				1,146
Maximum borrowing capacity | ¥					50,000
Annual interest rate			5.66%
Line of credit due date			Apr. 2, 2020
Line of Credit Due on April 1, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	4,404		$ 4,404				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			4.70%
Line of credit due date			Apr. 1, 2021
Line of Credit Due on June 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,321		$ 1,321				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			4.25%
Line of credit due date			Jun. 27, 2021
Line of Credit Due on April 29, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	820		$ 820				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			2.80%
Line of credit due date			Apr. 29, 2021
Line of Credit Due on June 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,079		$ 2,079				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			2.70%
Line of credit due date			Jun. 27, 2021
Line of Credit Due on April 12, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,468		$ 1,468				0
Maximum borrowing capacity | ¥					20,000
Annual interest rate			4.65%
Line of credit due date			Apr. 12, 2021
Line of Credit Due on May 24, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,468		$ 1,468				0
Maximum borrowing capacity | ¥					20,000
Annual interest rate			3.65%
Line of credit due date			May 24, 2021
Line of Credit Due on May 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,466		$ 2,466				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			4.68%
Line of credit due date			May 27, 2021
Line of Credit Due on June 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,321		$ 1,321				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			4.68%
Line of credit due date			Jun. 27, 2021
Line of Credit Due on May 28, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,441		$ 2,441				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			3.48%
Line of credit due date			May 28, 2021
Line of Credit Due on June 7, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,521		$ 1,521				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			3.50%
Line of credit due date			Jun. 7, 2021
Line of Credit Due on June 16, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,837		$ 1,837				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			3.50%
Line of credit due date			Jun. 16, 2021
Line of Credit Due on December 17, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,496		$ 2,496				0
Maximum borrowing capacity | ¥					30,000
Annual interest rate			4.35%
Line of credit due date			Dec. 17, 2020
Line of Credit Due on August 10, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,321		$ 1,321				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			3.85%
Line of credit due date			Aug. 10, 2021
Line of Credit Due on August 25, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,936		$ 2,936				0
Maximum borrowing capacity | ¥					¥ 80,000
Annual interest rate			3.85%
Line of credit due date			Aug. 25, 2021
Line of Credit Due on July 11, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	$ 428		$ 428				$ 0
Maximum borrowing capacity | ₩						₩ 500,000
Annual interest rate			3.99%
Line of credit due date			Jul. 11, 2021

OTHER PAYABLE AND ACCRUED EXP_3

OTHER PAYABLE AND ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
OTHER PAYABLE AND ACCRUED EXPENSES [Abstract]
Accrued commissions	$ 7,785	$ 4,082
Accrued warranty	3,449	2,811
Accrued payroll	2,960	2,092
Accrued professional fees	40	165
Accrued machine testing fees	1,481	1,456
Others	2,779	2,268
Total	$ 18,494	$ 12,874

LEASES (Details)

LEASES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Components of lease expense [Abstract]
Operating lease cost	$ 384	$ 363	$ 1,139	$ 1,064
Short-term lease cost	73	92	170	117
Lease cost	457	455	1,309	1,181
Cash paid for amounts included in the measurement of lease liabilities [Abstract]
Operating cash outflow from operating leases	457	$ 455	1,309	$ 1,181
Maturities of lease liabilities [Abstract]
2020	390		390
2021	1,592		1,592
2022	1,580		1,580
2023	912		912
2024	872		872
2025	22		22
Total lease payments	5,368		5,368
Less: interest	(800)		(800)
Present value of lease liabilities	$ 4,568		$ 4,568
Weighted average remaining lease terms and discount rates [Abstract]
Weighted average remaining lease term	3 years 8 months 12 days		3 years 8 months 12 days		3 years 7 days
Weighted average discount rate	5.29%		5.29%		5.43%

OTHER LONG-TERM LIABILITIES (De

OTHER LONG-TERM LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Long-term Liabilities [Abstract]
Other long-term liabilities	$ 6,454	$ 4,186
Subsidies to Stress Free Polishing Project, Commenced in 2008 and 2017 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	1,126	1,251
Subsidies to Electro Copper Plating Project, Commenced in 2014 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	2,188	2,666
Subsidies to Polytetrafluoroethylene, Commenced in 2018 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	125	135
Subsidies to Tahoe-Single Bench Clean, Commenced in 2020 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	1,962	0
Subsidies to Backside Clean-YMTC National Project, Commenced in 2020
Other Long-term Liabilities [Abstract]
Other long-term liabilities	751	0
Other [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	$ 302	$ 134

LONG TERM INVESTMENTS (Details)

LONG TERM INVESTMENTS (Details) $ / shares in Units, $ in Thousands	Sep. 05, 2019shares	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 27, 2019USD ($)	Sep. 11, 2017USD ($)$ / sharesshares
Classification of Investments [Abstract]
Total		$ 6,580	$ 5,934
Ninebell [Member]
Investments [Abstract]
Percentage of ordinary shares issued						20.00%
Purchase price						$ 1,200
Classification of Investments [Abstract]
Total		2,088	1,538
Ninebell [Member] | Class A Common Stock [Member]
Investments [Abstract]
Purchase price						$ 1,000
Shares issued (in shares) | shares						133,334
Share price (in dollars per share) | $ / shares						$ 7.50
Shengyi [Member]
Investments [Abstract]
Percentage of ordinary shares issued					15.00%
Investment - equity method					$ 109
Number of investors with agreements entered | shares	6
Classification of Investments [Abstract]
Total		134	107
Hefei Shixi [Member]
Investments [Abstract]
Investment in partnership				$ 4,200
Ownership percentage in partnership				10.00%
Classification of Investments [Abstract]
Total		$ 4,358	$ 4,289

TRADING SECURITIES (Details)

TRADING SECURITIES (Details) $ in Thousands, ¥ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 18, 2020USD ($)	Jun. 18, 2020CNY (¥)	Dec. 31, 2019USD ($)
Trading securities listed in Shanghai Stock Exchange [Abstract]
Cost	$ 14,680	$ 14,680			$ 0
Market value	23,888	23,888			$ 0
Unrealized gain on trading securities	$ 8,970	$ 8,970
Qingdao LP [Member]
Investments [Abstract]
Total capital fund of limited partnership			$ 315,000	¥ 2,224
Investment in partnership			$ 14,200	¥ 100
Ownership percentage in partnership			4.30%	4.30%
SMIC [Member] | Minimum [Member]
Investments [Abstract]
Ownership percentage in partnership	30.00%	30.00%

FINANCIAL LIABILITY CARRIED A_3

FINANCIAL LIABILITY CARRIED AT FAIR VALUE (Details) $ / shares in Units, ¥ in Thousands, $ in Thousands

Jul. 29, 2020USD ($)$ / sharesshares

Apr. 30, 2020USD ($)Agreementshares

Aug. 31, 2019USD ($)$ / sharesshares

Mar. 31, 2018USD ($)shares

Mar. 31, 2017USD ($)$ / sharesshares

Sep. 30, 2020USD ($)$ / sharesshares

Sep. 30, 2019USD ($)

Sep. 30, 2020USD ($)$ / sharesshares

Sep. 30, 2019USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2016CNY (¥)

Related Party Transaction [Abstract]

Shares issued value

$ 26,463

$ 26,463

Change in fair value of financial liability

$ 6,533

$ 0

$ 11,964

$ 0

SMC 2020 Warrants [Member]

Related Party Transaction [Abstract]

Financial liability carried at fair value

$ 21,679

Change in fair value of financial liability

6,533

11,964

Fair value warrant amount

$ 21,679

$ 21,679

Fair Value of Options Granted [Abstract]

Fair value of common share (in dollars per share) | $ / shares

[1]

$ 89.28

$ 89.28

Expected term

[2]

3 years 5 months 1 day

Volatility

[3]

47.42%

Expected dividend

[4]

0.15%

Risk-free interest rate

[5]

0.00%

Common Class A [Member]

Fair Value of Options Granted [Abstract]

Fair value of common share (in dollars per share) | $ / shares

$ 13.195

Common Class A [Member] | SMC 2020 Warrants [Member]

Related Party Transaction [Abstract]

Shares issued (in shares) | shares

242,681

Fair Value of Options Granted [Abstract]

Fair value of common share (in dollars per share) | $ / shares

$ 7.50

ACM Shanghai [Member]

Related Party Transaction [Abstract]

Repayments of notes

$ 1,161

Number of agreement | Agreement

2

ACM Shanghai [Member] | Senior Secured Promissory Note [Member]

Related Party Transaction [Abstract]

Receivables

$ 1,820

ACM Shanghai [Member] | Intercompany Note [Member]

Related Party Transaction [Abstract]

Promissory note principal amount

$ 2,981

Interest rate on promissory note

3.01%

Promissory note maturity date

Aug. 17, 2023

Fair value warrant amount

$ 1,820

SMC [Member]

Related Party Transaction [Abstract]

Payment for investment

$ 2,981

¥ 20,123,500

Investment repayment period

60 days

Number of shares repurchased/surrender in exchange (in shares) | shares

242,681

154,821

Repayments of notes

$ 882

Investment due amount

$ 1,820

Consideration price in fair value

$ 9,715

Fair Value of Options Granted [Abstract]

Fair value of common share (in dollars per share) | $ / shares

$ 13.195

SMC [Member] | Senior Secured Promissory Note [Member]

Related Party Transaction [Abstract]

Promissory note principal amount

$ 2,981

Interest rate on promissory note

3.01%

Promissory note maturity date

Aug. 17, 2023

SMC [Member] | Common Class A [Member]

Related Party Transaction [Abstract]

Shares issued (in shares) | shares

397,502

Shares issued value

$ 2,981

Number of shares repurchased/surrender in exchange (in shares) | shares

242,681

242,681

Fair Value of Options Granted [Abstract]

Fair value of common share (in dollars per share) | $ / shares

$ 7.50

SMC [Member] | Common Class A [Member] | Senior Secured Promissory Note [Member]

Related Party Transaction [Abstract]

Exercise of common stock warrant issued (in shares) | shares

397,502

SMC [Member] | ACM Shanghai [Member]

Related Party Transaction [Abstract]

Repayment of investment in cash

$ 1,820

$ 1,161

[1]

Fair value of Class A common stock was the closing market price of the Class A common stock on July 29, 2020.

[2]

Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110.

[3]

Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant.

[4]

Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant.

[5]

Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock.

RELATED PARTY BALANCES AND TR_3

RELATED PARTY BALANCES AND TRANSACTIONS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related Party Transaction [Abstract]
Accounts payable	$ 3,806		$ 3,806		$ 1,215
Purchase of materials	4,628	$ 2,852	10,665	$ 7,848
Service fee charged by	36	0	226	0
Ninebell Co., Ltd [Member]
Related Party Transaction [Abstract]
Prepaid expenses	2,272		2,272		348
Accounts payable	3,197		3,197		727
Purchase of materials	4,029	2,591	9,552	7,395
Service fee charged by	22	0	22	0
Shengyi Semiconductor Technology Co., Ltd [Member]
Related Party Transaction [Abstract]
Accounts payable	609		609		$ 488
Purchase of materials	599	261	1,113	453
Service fee charged by	$ 14	$ 0	$ 204	$ 0

COMMON STOCK (Details)

COMMON STOCK (Details)	1 Months Ended		3 Months Ended		9 Months Ended
	Apr. 30, 2020shares	Aug. 31, 2019shares	Sep. 30, 2020Vote$ / sharesshares	Sep. 30, 2019shares	Sep. 30, 2020Vote$ / sharesshares	Sep. 30, 2019shares	Dec. 31, 2019$ / sharesshares
Class of Stock [Abstract]
Number of shares cancelled (in shares)			242,681		242,681
SMC [Member]
Class of Stock [Abstract]
Share cancellation (in shares)	242,681	154,821
Common Class A [Member]
Class of Stock [Abstract]
Common stock, shares authorized (in shares)			50,000,000		50,000,000		50,000,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.0001		$ 0.0001		$ 0.0001
Number of votes for each share entitled | Vote			1		1
Common stock, shares issued (in shares)			16,657,135		16,657,135		16,182,151
Common stock, shares outstanding (in shares)			16,657,135		16,657,135		16,182,151
Common Class A [Member] | SMC [Member]
Class of Stock [Abstract]
Share cancellation (in shares)			242,681		242,681
Common Class A [Member] | Common Stock [Member]
Class of Stock [Abstract]
Exercise of common stock warrant issued (in shares)					64,717
Stock issued upon exercise of stock options (in shares)			407,043	89,015	592,946	193,642
Share cancellation (in shares)				214,286	242,681	214,286
Common Class B [Member]
Class of Stock [Abstract]
Common stock, shares authorized (in shares)			2,409,738		2,409,738		2,409,738
Common stock, par value (in dollars per share) | $ / shares			$ 0.0001		$ 0.0001		$ 0.0001
Number of votes for each share entitled | Vote			20		20
Convertible shares in to Class A common stock (in shares)					1
Common stock, shares issued (in shares)			1,802,606		1,802,606		1,862,608
Common stock, shares outstanding (in shares)			1,802,606		1,802,606		1,862,608
Common Class B [Member] | Common Stock [Member]
Class of Stock [Abstract]
Exercise of common stock warrant issued (in shares)					0
Stock issued upon exercise of stock options (in shares)			0	0	0	0
Share cancellation (in shares)				0	0	0

REDEEMABLE NON-CONTROLLING IN_3

REDEEMABLE NON-CONTROLLING INTERESTS (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Change in Redeemable Non-controlling Interests [Abstract]
Balance	$ 60,162
Net income attributable to redeemable non-controlling interests	643
Effect of foreign currency translation gain attributable to redeemable non-controlling interests	(847)
Reclassification of redeemable non-controlling interest	(59,958)
Balance	$ 0

STOCK-BASED COMPENSATION, Stock

STOCK-BASED COMPENSATION, Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	$ 2,779	$ 1,557	$ 4,323	$ 2,919
Employee Stock Purchase Plan [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	2,651	1,329	3,717	1,841
Employee Stock Purchase Plan [Member] | ACM Shanghai [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	84	0	250	0
Non-Employee Stock Purchase Plan [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	44	228	356	1,078
Cost of Revenue [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	44	154	132	213
Sales and Marketing Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	237	172	495	252
Research and Development Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	193	759	568	939
General and Administrative Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	$ 2,305	$ 472	$ 3,128	$ 1,515

STOCK-BASED COMPENSATION, Share

STOCK-BASED COMPENSATION, Share Option Activities (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Weighed Average Remaining Contractual Term [Abstract]
Stock-based compensation expense	$ 2,779	$ 1,557	$ 4,323	$ 2,919
Employee Share Option [Member]
Number of Option Share [Roll Forward]
Outstanding, beginning of period (in shares)			2,994,063
Granted (in shares)			778,399
Exercised (in shares)			(327,917)
Expired (in shares)			0
Forfeited/cancelled (in shares)			(40,515)
Outstanding, end of period (in shares)	3,404,030		3,404,030		2,994,063
Vested and exercisable (in shares)	2,061,793		2,061,793
Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)			$ 2.59
Granted (in dollars per share)			11.98
Exercised (in dollars per share)			1.56
Expired (in dollars per share)			0
Forfeited/cancelled (in dollars per share)			4.94
Outstanding at end of period (in dollars per share)	$ 4.81		4.81		$ 2.59
Weighted Average Exercise Price [Abstract]
Outstanding, beginning of period (in dollars per share)			6.77
Granted (in dollars per share)			28.70
Exercised (in dollars per share)			4.33
Expired (in dollars per share)			0
Forfeited/cancelled (in dollars per share)			13.04
Outstanding, end of period (in dollars per share)	$ 11.95		$ 11.95		$ 6.77
Weighed Average Remaining Contractual Term [Abstract]
Outstanding weighed average remaining contractual term			7 years 1 month 20 days		7 years 18 days
Stock-based compensation expense	$ 2,651	1,329	$ 3,717	1,841
Unrecognized employee stock-based compensation expense	$ 9,697		$ 9,697		$ 4,712
Weighted-average period over which unrecognized compensation is expected to be recognized			1 year 11 months 15 days		1 year 5 months 19 days
Employee Share Option [Member] | ACM Shanghai [Member]
Number of Option Share [Roll Forward]
Outstanding, beginning of period (in shares)			0
Granted (in shares)			5,869,808
Exercised (in shares)			0
Expired (in shares)			0
Forfeited/cancelled (in shares)			(330,770)
Outstanding, end of period (in shares)	5,539,038		5,539,038		0
Vested and exercisable (in shares)	0		0
Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)			$ 0
Granted (in dollars per share)			0.22
Exercised (in dollars per share)			0
Expired (in dollars per share)			0
Forfeited/cancelled (in dollars per share)			0.23
Outstanding at end of period (in dollars per share)	$ 0.22		0.22		$ 0
Weighted Average Exercise Price [Abstract]
Outstanding, beginning of period (in dollars per share)			0
Granted (in dollars per share)			1.87
Exercised (in dollars per share)			0
Expired (in dollars per share)			0
Forfeited/cancelled (in dollars per share)			1.87
Outstanding, end of period (in dollars per share)	$ 1.87		$ 1.87		$ 0
Weighed Average Remaining Contractual Term [Abstract]
Outstanding weighed average remaining contractual term			3 years 9 months 3 days		0 years
Stock-based compensation expense	$ 84	0	$ 250	0
Non-Employee Stock Option [Member]
Number of Option Share [Roll Forward]
Outstanding, beginning of period (in shares)			1,101,613
Granted (in shares)			20,000
Exercised (in shares)			(265,029)
Expired (in shares)			0
Forfeited/cancelled (in shares)			(111)
Outstanding, end of period (in shares)	856,473		856,473		1,101,613
Vested and exercisable (in shares)	819,819		819,819
Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)			$ 0.82
Granted (in dollars per share)			10.29
Exercised (in dollars per share)			0.91
Forfeited/cancelled (in dollars per share)			0.30
Outstanding at end of period (in dollars per share)	$ 1.01		1.01		$ 0.82
Weighted Average Exercise Price [Abstract]
Outstanding, beginning of period (in dollars per share)			2.69
Granted (in dollars per share)			25.60
Exercised (in dollars per share)			3.34
Forfeited/cancelled (in dollars per share)			0.75
Outstanding, end of period (in dollars per share)	$ 3.02		$ 3.02		$ 2.69
Weighed Average Remaining Contractual Term [Abstract]
Outstanding weighed average remaining contractual term			5 years 1 month 9 days		5 years 10 months 6 days
Stock-based compensation expense	$ 44	$ 228	$ 356	$ 1,078
Unrecognized employee stock-based compensation expense	235		$ 235		$ 406
Weighted-average period over which unrecognized compensation is expected to be recognized			1 month 9 days		2 months 23 days
Non-Employee Stock Option [Member] | ACM Shanghai [Member]
Weighed Average Remaining Contractual Term [Abstract]
Unrecognized employee stock-based compensation expense	$ 911		$ 911
Weighted-average period over which unrecognized compensation is expected to be recognized			2 years 9 months

STOCK-BASED COMPENSATION, Assum

STOCK-BASED COMPENSATION, Assumptions Used to Determine Fair Value of Share Options Granted (Details) - $ / shares		9 Months Ended	12 Months Ended
		Sep. 30, 2020	Dec. 31, 2019
Employee Share Option [Member] | Market Based [Member]
Fair Value of Options Granted [Abstract]
Fair value of common share (in dollars per share)	[1]	$ 22.07
Volatility	[2]	45.10%
Risk-free interest rate	[3]	2.68%
Expected dividend	[4]	0.00%
Employee Share Option [Member] | Market Based [Member] | Minimum [Member]
Fair Value of Options Granted [Abstract]
Expected term in years	[5]	9 years 2 months 12 days
Employee Share Option [Member] | Market Based [Member] | Maximum [Member]
Fair Value of Options Granted [Abstract]
Expected term in years	[5]	9 years 9 months 18 days
Employee and Non-employee Stock Option [Member] | Service Period Based [Member]
Fair Value of Options Granted [Abstract]
Expected term in years	[5]		6 years 3 months
Expected dividend	[4]	0.00%	0.00%
Employee and Non-employee Stock Option [Member] | Service Period Based [Member] | Minimum [Member]
Fair Value of Options Granted [Abstract]
Fair value of common share (in dollars per share)	[1]	$ 22.07	$ 13.64
Expected term in years	[5]	5 years 6 months
Volatility	[2]	42.17%	39.91%
Risk-free interest rate	[3]	0.27%	1.69%
Employee and Non-employee Stock Option [Member] | Service Period Based [Member] | Maximum [Member]
Fair Value of Options Granted [Abstract]
Fair value of common share (in dollars per share)	[1]	$ 85.27	$ 16.81
Expected term in years	[5]	6 years 3 months
Volatility	[2]	48.15%	40.35%
Risk-free interest rate	[3]	0.82%	2.46%
[1]	Fair value of Class A common stock value was the closing market price of the Class A common stock on the grant date.
[2]	Volatility is calculated based on the historical volatility of the stock of companies comparable to ACM in the period equal to the expected term of each grant.
[3]	Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant.
[4]	Expected dividend is assumed to be 0% as ACM has no history or expectation of paying a dividend on its common stock.
[5]	Expected term of share options is based on the average of the vesting period and the contractual term for each grant according to Staff Accounting Bulletin 110.

INCOME TAXES (Details)

INCOME TAXES (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)Subsidiary	Sep. 30, 2019USD ($)
Income Taxes [Abstract]
Statutory U.S federal income tax rate			21.00%
Total income tax benefit (expense)	$ 1,747	$ 328	$ (416)	$ (667)
Unrecognized tax benefits	155		155
Interest or penalties	0
Income Tax Expense [Abstract]
Total income tax benefit (expense)	$ 1,747	$ 328	$ (416)	$ (667)
China [Member]
Income Taxes [Abstract]
Number of subsidiaries | Subsidiary			3
Effective period of preferential income tax rate			3 years
China [Member] | ACM Research (Shanghai), Inc. [Member]
Income Taxes [Abstract]
Foreign corporate tax rate			15.00%
China [Member] | ACM Research (Wuxi), Inc. [Member]
Income Taxes [Abstract]
Foreign corporate tax rate			25.00%
China [Member] | Shengwei Research (Shanghai), Inc. [Member]
Income Taxes [Abstract]
Foreign corporate tax rate			25.00%

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands, ¥ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2020CNY (¥)
COMMITMENTS AND CONTINGENCIES [Abstract]
Open capital commitments	$ 1,369
Required liquidate damage value	$ 63,400	¥ 450
Land use rights period	6 years	6 years
Annual total taxes	$ 22,000	¥ 157.6