SCHEDULE 14A

(Rule 14A-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  ☒                              Filed by a Party other than the Registrant  ☐

Check the appropriate box:

ULTRA CLEAN HOLDINGS, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if Other Than the Registrant)

Payment of Filing Fee (Check the appropriate box):

ULTRA CLEAN HOLDINGS, INC.

26462 Corporate Avenue

Hayward, CA 94545

NOTICE OF 20182021 ANNUAL MEETING OF STOCKHOLDERS OF

ULTRA CLEAN HOLDINGS, INC.

Sincerely,

/s/ James P. Scholhamer

James P. Scholhamer

Chief Executive Officer

April 19, 201826, 2021

ULTRA CLEAN HOLDINGS, INC.

20182021 ANNUAL MEETING OF STOCKHOLDERS

NOTICE OF ANNUAL MEETING AND PROXY STATEMENT

TABLE OF CONTENTS

ULTRA CLEAN HOLDINGS, INC.

26462 Corporate Avenue

Hayward, CA 94545

PROXY STATEMENT FOR 20182021 ANNUAL MEETING OF STOCKHOLDERS

May 15, 201820, 2021

INFORMATION CONCERNING SOLICITATION AND VOTING

Your vote is very important. For this reason, our Board of Directors is requesting that you permit your shares of common stock to be represented at our 20182021 Annual Meeting of Stockholders by the proxies named on the enclosed proxy card. This proxy statement contains important information for you to consider in deciding how to vote on the matters brought before the meeting. The date of this proxy statement is April 19, 2018.26, 2021. The proxy statement and form of proxy are first being mailed to our stockholders on or about April 20, 2018.27, 2021.

Important Notice Regarding The Availability Of Proxy Materials For The Stockholder Meeting To Be Held On May 15, 2018:20, 2021: This Proxy Statement, along with our 20172020 Annual Report to Stockholders, is available on the following website: http://materials.proxyvote.com/90385V.

General Information

Ultra Clean Holdings, Inc., referred to in this proxy statement as “Ultra Clean,” the “Company” or “we,” is soliciting the enclosed proxy for use at our Annual Meeting of Stockholders to be held on May 15, 201820, 2021 at 12:30 p.m., Pacific time or at any adjournment thereof for the purposes set forth in this proxy statement. OurDue to the continued public health impact of the coronavirus outbreak (COVID-19), our annual meeting will be helda virtual meeting of stockholders, which will be conducted via a live audio webcast. You will be able to attend the Annual Meeting, submit your questions and vote online during the meeting by visiting www.virtualshareholdermeeting.com/UCTT2021.

In the event of an adjournment, postponement or emergency that may change the Annual Meeting’s time, date or location, we will make an announcement, issue a press release or post information at the offices of Davis Polk & Wardwell LLP, 1600 El Camino Real, Menlo Park, California 94025.www.uct.com/investors to notify stockholders, as appropriate. Information on or accessible through our website is not incorporated by reference in this Proxy Statement.

Who May Attend and Vote at Our Annual Meeting

All holders of our common stock, as reflected in our records at the close of business on March 21, 2018,31, 2021, the record date for voting, may attend and vote at the meeting. To attendbe admitted to the annual meeting,Annual Meeting at www.virtualshareholdermeeting.com/UCTT2021, you must present photo identification for admittance. If you are not a stockholder of record but hold shares as a beneficial owner in street name, you must also provide proof of beneficial ownership as ofenter the record date, such ascontrol number found on your most recent account statement prior to the record date, a copy of theproxy card, voting instruction card provided by your broker, bank, trustee,form or nominee, or other similar evidence of ownership.notice you previously received.

Each share of common stock that you owned on the record date entitles you to one vote on each matter properly brought before the meeting. As of the record date, there were issued and outstanding 38,718,17340,659,905 shares of our common stock, $0.001 par value.

Holding Shares as a “Beneficial Owner” (or in “Street Name”)

Most stockholders are considered the “beneficial owners” of their shares, that is, they hold their shares through a broker, bank or nominee rather than directly in their own names. As summarized below, there are some distinctions between shares held of record and those owned beneficially or in “street name.”

Stockholder of RecordRecord.. If your shares are registered directly in your name with our transfer agent, you are considered the stockholder of record with respect to those shares. If you are a stockholder of record, we are sending paper copies of the proxy materials directly to you. As our stockholder of record, you have the right to grant your voting proxy directly to us by signing and mailing the enclosed proxy card or by voting on the Internet or telephone or in person at the annual meeting.

Beneficial OwnerOwner.. If your shares are held in a stock brokerage account or by a bank or nominee, you are considered the beneficial owner of shares held in street name, and the proxy statement is being forwarded to you by or on behalf of your broker, bank or nominee (who is considered the stockholder of record with respect to those shares). As the beneficial owner, you have the right to direct your broker, bank, or nominee how to vote by following the instructions you receive from your broker, bank or nominee. You are also invited to attend the annual meeting. However, since you are not the stockholder of record, you may not vote these shares in person at the annual meeting unless you request, complete and deliver a proxy from your broker, bank or nominee.

How to Vote

You may vote in person at the virtual meeting or by proxy.

Voting by Proxy.If you are a stockholder of record, you may vote by proxy over the Internet, by telephone or by mail if you complete and return the enclosed proxy card by following the instructions on the proxy card. If your shares are held in street name, you have the right to direct your broker, bank or nominee how to vote by following the instructions you receive from your broker, bank or nominee. The shares voted electronically, telephonically or represented by the proxy cards received, properly marked, dated, signed and not revoked, will be voted at the annual meeting. We recommend that you vote by proxy even if you plan to attend the meeting. You may change your vote at the meeting even if you have previously submitted a proxy.

Voting at the Annual Meeting. The method or timing of your vote will not limit your right to vote at the annual meeting if you attend the annual meeting and vote in person.meeting. However, if your shares are held in the name of a bank, broker or other nominee, you must obtain a legal proxy, executed in your favor, from the holder of record to be able to vote at the annual meeting. You should allow yourself enough time prior to the annual meeting to obtain this proxy from the holder of record.

How Proxies Work

This proxy statement is furnished in connection with the solicitation of proxies by us for use at the annual meeting and at any adjournment of that meeting. If you give us your proxy, you authorize us to vote your shares at the meeting in the manner you direct. You may vote for all, some or none of our director candidates. You may also vote for or against the other proposals, or you may abstain from voting.

If you give us your proxy but do not specify how your shares shall be voted on a particular matter, your shares will be voted:

Changing or Revoking Your Vote

You have the right to revoke your previously submitted proxy at any time before your proxy is exercised at the annual meeting.

If you are the stockholder of record, you may revoke your proxy by resubmitting your vote on a later date on the Internet or by telephone (only your latest Internet or telephone proxy submitted prior to the annual meeting will be counted), by signing and returning a new proxy card with a later date, by attending and voting at the annual meeting and voting in person or by giving written notice to our Secretary that you wish to revoke your previously submitted proxy.

If you hold shares beneficially in street name, you may revoke your proxy by submitting new voting instructions to your broker, bank or nominee by following the instructions they providedprovide you or, if you have obtained a legal proxy from your broker, bank or nominee giving you the right to vote your shares, by attending and voting at the annual meeting and voting in person.meeting.

Note that for both stockholders of record and beneficial owners, attendance at the annual meeting will not cause your previously granted proxy to be revoked unless you specifically so request or vote in person at the annual meeting.

Important Notice Regarding Delivery of Stockholder Documents

Only one proxy statement, annual report and set of accompanying materials, if applicable, are being delivered by us to multiple stockholders sharing an address, who have consented to receiving one set of such materials, until we receive contrary instructions from any such stockholders. We will deliver, promptly upon written or oral request, a separate copy of such materials to a stockholder at a shared address to which a single copy of such materials was delivered. A stockholder who wishes to receive a separate copy of the proxy statement and accompanying materials now or in the future, or stockholders sharing an address who are receiving multiple copies of the proxy statement and accompanying materials and wish to receive a single copy of such materials, should submit a request to Broadridge, c/o Householding Department, 51 Mercedes Way, Edgewood, NY 11717 or call800-542-1061.

Attending in Person

Any stockholder of record may vote in person at the annual meeting of our stockholders. All meeting attendees will be required to present a valid, government-issued photo identification, such as a driver’s license or passport, in order to enter the meeting.

If you are a beneficial owner and your shares are held in the name of your broker, bank or nominee, you must bring a proxy from your broker, bank or nominee in order to vote in person.

Votes Needed to Hold the Meeting and Approve Proposals

In order to carry on the business of the annual meeting, stockholders entitled to cast a majority of the votes at a meeting of stockholders must be represented at the meeting, either in person or by proxy. In accordance with Delaware law, only votes cast “for” a matter constitute affirmative votes. A properly executed proxy marked “abstain” with respect to any matter will not be voted, although it will be counted for purposes of determining whether there is a quorum. Since abstentions will not be votes cast for a particular proposal, they will have the same effect as negative votes or votes against that proposal. Brokernon-votes are also counted for the purpose of determining the presence of a quorum. Brokernon-votes occur when shares held by a broker on behalf of a beneficial owner are not voted with respect to a particular proposal, which generally occurs when the broker has not received voting instructions from the beneficial owner and lacks the discretionary authority to vote the shares itself.

Election of DirectorsDirectors.. Our Amended and Restated Bylaws provides that a director nominee must receive a majority of the votes cast with respect to such nominee in uncontested director elections (i.e., the number of shares voted “for” a director nominee must exceed the number of shares voted “against” such nominee). If an incumbent director nominee fails to receive a majority of the votes cast in an uncontested election, the director shall immediately tender his or her resignation to the Board. The Nominating and Corporate Governance Committee of the Board, or such other committee designated by the Board, shall make a recommendation to the Board as to whether to accept or reject the resignation of such incumbent director, or whether other action should be taken. The Board shall act on the resignation, taking into account the committee’s recommendation, and publicly disclose its decision regarding the resignation within 90 days following certification of the election

results. If the Board accepts a director’s resignation, or if a nominee for director is not elected and the nominee is not an incumbent director, the remaining members of the Board may fill the resulting vacancy or may decrease the size of the Board.

Brokers do not have discretionary authority to vote shares without instructions from beneficial owners in the election of directors. Therefore, beneficial owners who are not stockholders of record and who want their votes to be counted in the election of directors must give voting instructions to their bank, broker or nominee before the date of the annual meeting.

Ratification of the appointment of our independent registered public accounting firmfirm.. The affirmative vote of the holders of a majority of the shares of common stock present in person or represented by proxy and entitled to vote on the proposal will be required to ratify the appointment of our independent registered public accounting firm for the current fiscal year. We believe that the ratification of our independent registered public accounting firm is a routine proposal for which brokers may vote shares held on behalf of beneficial owners who have not given voting instructions with respect to that proposal.

Advisory vote on the compensation of our named executive officersofficers.. The affirmative vote of the holders of a majority of the shares of common stock present in person or represented by proxy and entitled to vote on the proposal will be sufficient to approve, by an advisory,non-binding vote, the compensation of our named executive officers for fiscal 2017.2020. The advisory vote on the compensation of our named executive officers, while held annually, is not considered a routine proposal; therefore, brokers lack the discretionary authority to vote shares without instructions from beneficial owners for this proposal.

Approval of any other matter properly submitted to the stockholders at the annual meeting generally will require the affirmative vote of the holders of a majority of the shares of common stock present in person or represented by proxy and entitled to vote on that matter.

Security Ownership of Certain Beneficial Owners and Management

The table below sets forth information as of March 21, 2018 (the record date for our 2018 Annual Meeting)1, 2021 regarding the beneficial ownership (as defined by Rule13d-3(d)(1) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) of our common stock by:

In accordance with applicable rules of the Securities and Exchange Commission (the “SEC”), beneficial ownership includes voting or investment power with respect to securities and includes the shares issuable pursuant to stock options that are exercisable, and shares subject to restricted stock units that vest and are delivered, within 60 days of March 21, 2018.1, 2021. Shares issuable pursuant to the exercise of stock options, and restricted stock units that vest, in the 60 days following March 21, 2018,1, 2021, are deemed outstanding for the purpose of computing the ownership percentage of the person holding such options, or shares subject to restricted stock units, but are not deemed outstanding for computing the ownership percentage of any other person. The percentage of beneficial ownership for the following table is based on 38,718,17340,618,631 shares of common stock outstanding as of March 21, 2018.1, 2021.

The address of each of the named individuals in the table below is c/o Ultra Clean Holdings, Inc., 26462 Corporate Avenue, Hayward, CA 94545 unless otherwise indicated below. To our knowledge, except as indicated in the footnotes to this table and pursuant to applicable community property laws, the persons named in the table have sole voting and investment power with respect to all shares of common stock.

12, 2021.

(10)	Includes 7,500 restricted stock awards that vest on May 14, 2018. Also includes 15,000 shares held by the Revocable Trust of Leonid Mezhvinsky and Inna Mezhvinsky, dated April 26, 1988, for which Mr. Mezhvinsky is deemed a beneficial owner.

At the close of business on March 21, 2018,31, 2021, the record date, we had 38,718,17340,659,905 shares of common stock outstanding. Each share of our common stock is entitled to one vote on all matters properly submitted for a stockholder vote.

Delinquent Section 16(a) Beneficial Ownership Reporting ComplianceReports

Section 16(a) requires our directors, executive officers and beneficial holders of 10% or more of a registered class of our equity securities to file certain reports with the SEC regarding ownership of, and transactions in, our equity securities. Based solely on a review of Forms 3, 4 and 5 and amendments thereto furnished to us and written representations we received from our directors and officers required to file the reports, we believe that all of our directors, executive officers and beneficial holders of 10% or more of a registered class of our equity securities, filed, on a timely basis, all reports required by Section 16(a) of the Exchange Act for the year ended December 29, 2017, except:25, 2020.

Cost of Proxy Solicitation

We will pay the cost of this proxy solicitation. Some of our employees may also solicit proxies, without any additional compensation. We may also reimburse banks, brokerage firms and nominees for their expenses in forwarding proxy materials to their customers who are beneficial owners of our common stock and obtaining their voting instructions.

Deadline for Receipt of Stockholder Proposals

If you wish to submit a proposal for inclusion in the proxy statement for our 20192022 Annual Meeting of Stockholders, you must follow the procedures outlined in Rule14a-8 of the Exchange Act, and we must receive your proposal at the address below no later than December 21, 2018.January 20, 2022. Stockholders intending to present a proposal at the next annual meeting without the inclusion of such proposal in the Company’s proxy materials, including for the election of director nominees, must comply with the requirements set forth in our Amended and Restated Bylaws. The Amended and Restated Bylaws require, among other things, that a stockholder must submit a written notice of intent to present such a proposal at the address below not less than 90 days nor more than 120 days prior to the first anniversary of the preceding year’s annual meeting of stockholders (as long as the date of the annual meeting is not advanced more than 30 days prior to such anniversary date or delayed more than 70 days after such anniversary date, in which case notice must be received no earlier than 120 days prior to such meeting and no later than the later of 70 days prior to such meeting or the 10th day following the public

announcement of the date of such meeting). Therefore, we must receive notice of such proposal for the 20192022 Annual Meeting of Stockholders no earlier than January 15, 2019,20, 2022, and no later than February 14, 2019,19, 2022, otherwise such notice will be considered untimely and we will not be required to present it at the 20192022 Annual Meeting of

Stockholders. The Company reserves the right to reject, rule out of order or take other appropriate action with respect to any proposal that does not comply with these and other applicable requirements.

Contacting Ultra Clean

If you have questions or would like more information about the annual meeting, you can contact us in either of the following ways:

PROPOSAL 1: ELECTION OF DIRECTORS

Our Amended and Restated Bylaws provide that our Board of Directors shall be elected at the annual meeting of our stockholders, and each director so elected shall hold office until such director’s successor is elected and qualified or until such director’s earlier death, resignation or removal. Our Board of Directors, at the recommendation of the Nominating and Corporate Governance Committee, has recommended for nomination the nominees for director named below. All of these nominees currently serve as our directors. Each nominee has consented to serve as a nominee, to serve as a director if elected, and to being named a nominee in this Proxy Statement. If a director nominee becomes unavailable before the election, your proxy authorizes the people named as proxies to vote for a replacement nominee if our Board of Directors names one.

Our Amended and Restated Bylaws provide that a director nominee must receive a majority of the votes cast with respect to such nominee in uncontested director elections (i.e., the number of shares voted “for” a director nominee must exceed the number of shares voted “against” such nominee). If an incumbent director nominee fails to receive a majority of the votes cast in an uncontested election, the director shall immediately tender his or her resignation to the Board. The Nominating and Corporate Governance Committee of the Board, or such other committee designated by the Board, shall make a recommendation to the Board as to whether to accept or reject the resignation of such incumbent director, or whether other action should be taken. The Board shall act on the resignation, taking into account the committee’s recommendation, and publicly disclose its decision regarding the resignation within 90 days following certification of the election results. If the Board accepts a director’s resignation, or if a nominee for director is not elected and the nominee is not an incumbent director, the remaining members of the Board may fill the resulting vacancy or may decrease the size of the Board.

Members of our Board self-identify as set forth in the table below:

Set forth below is information about each of our nominees for director:

Clarence L. Granger has served as our Chairman since October 2006 and has been a member of our Board of Directors since May 2002. Mr. Granger formerly served as our Chief Executive Officer from November 2002 to January 2015. Mr. Granger served as our Executive Vice President and Chief Operating Officer from January 1998 to March 1999 and as our Executive Vice President of Operations from April 1996 to January 1998. Prior to joining Ultra Clean in April 1996, heMr. Granger served as vice presidentVice President of Media Operations for Seagate Technology, which designs, manufactures, markets and sells hard disk drives, from 1994 to 1996. Prior to that, Mr. Granger worked for HMT Technology, a supplier of high-performance thin-film disks, as chief executive officerChief Executive Officer from 1993 to 1994, as chief operating officerChief Operating Officer from 1991 to 1993 and as presidentPresident from 1989 to 1994. Prior to that, Mr. Granger worked for Xidex as vice presidentVice President and general manager,General Manager, Thin Film Disk Division, from 1988 to 1989, as vice president,Vice President, Santa Clara Oxide Disk Operations, from 1987 to 1988, as vice president,Vice President, U.S. Tape Operations, from 1986 to 1987 and as directorDirector of engineeringEngineering from 1983 to 1986. Mr. Granger holds a master’sMaster of scienceScience degree in industrial engineeringIndustrial Engineering from Stanford University and a bachelorBachelor of scienceScience degree in industrial engineeringIndustrial Engineering from the University of California at Berkeley. Our Board of Directors values Mr. Granger’s perspective as our former chief executive officerChief Executive Officer and his intimate knowledge of our employee base, operations, customers, suppliers and competitive position in the semiconductor capital equipment industry.

James P. Scholhamerjoined UCTthe Company as Chief Executive Officer and a member of our Board of Directors in January 2015.Prior to joining Ultra Clean, Mr. Scholhamer served as Corporate Vice President and General Manager of Applied Materials, Inc., leading the Equipment Products Group and Display Services Group of its Global Service Division from February 2011 to January 2015. Mr. Scholhamer joined Applied Materials, Inc. in 2006, where, prior to his most recent position, he served as Vice President of Operations-Energy, for the Environmental and Display Products Division from July 2006 to December 2008 and Corporate Vice President and General Manager of the Display Business Group from December 2008 to February 2011. Prior to that, Mr. Scholhamer worked for Applied Films Corporation as Vice President of Operations, Engineering and Research Development in the company’s German office from September 2002 to July 2006 and as Vice President of Thin Film Coating Division and Thin Film Equipment Division in the company’s Colorado office from July 2000 to September 2002. Mr. Scholhamer holds a Bachelor of Science degree in materialsMaterials and metallurgical engineeringMetallurgical Engineering from the University of Michigan. Our Board of Directors believes that Mr. Scholhamer brings strong engineering and operations experience to our Board of Directors and provides the Board of Directors with a unique perspective as our chief executiveChief Executive Officer and leader of our strategic planning process.

David T. ibnAlehas served as a director of Ultra Clean since November 2002 and served as our lead directorLead Director from February 2005 to February 2007. Mr. ibnAle is a Founding and Managing Partner of Advance Venture Partners, LLC. He has over twenty20 years of experience as an investor in small andmid-sized growth companies in the technology, media and communications sectors. Prior toco-founding AVPAdvance Venture Partners in 2014, Mr. ibnAle was a Managing Partner of Augusta Columbia Capital Group from 2011 to 2013, and a Managing Director of TPG Growth, the growth equity and middle market investment platform of TPG, from 2008 to 2011. Prior to joining TPG Growth, he was an investment professional and a Partner at Francisco Partners from 1999 to 2008, and he began his investing career at Summit Partners. Mr. ibnAle has served on the boards of directors of a number of public and private technology companies, and he currently serves on the boardsBoards of directorsDirectors of Above Average Productions, Hytrust,Affinity, E.Merge Technology Acquisition Corp., Ginger, Morning Consult, Nativo, UnifiedPebblePost and UrbanSitter. Mr. ibnAle holds a B.A.Bachelor of Arts degree in Public Policy and a M.A.Master’s degree in International Development Policy from Stanford University, and a M.B.A.Master’s degree in Business Administration from the Stanford University Graduate School of Business. Our Board of Directors values Mr. ibnAle’s experience as an investment professional, as well his experience in strategic planning and mergers and acquisitions, as he brings significant quantitative and qualitative financial experience to our Board of Directors. Mr. ibnAle qualifies as a financial expert and provides important support as a member of our Audit Committee.

Leonid Mezhvinsky has served as a director of Ultra Clean since February 2007. Mr. Mezhvinsky served as our president from June 2006 to December 2007, following our acquisition of Sieger Engineering, Inc. He has more than two decades of management experience andin-depth knowledge of machine shop, electro mechanical assemblies and system integration utilized in semiconductor, medical and biotech OEM products. Prior to joining Ultra Clean, Mr. Mezhvinsky was president and chief executive officer of Sieger Engineering, Inc. which he joined in 1982. Mr. Mezhvinsky holds the equivalent of a bachelor of science in Industrial Automation from The College of Industrial Automation, Odessa, Ukraine. Mr. Mezhvinsky brings to our Board of Directors substantial operational experience. As the former president of Sieger Engineering, which is now a part of our Company, he has a deep understanding of our competitors, suppliers, products and customers.

Emily M. Liggett has served as a director of Ultra Clean since May 2014. Ms. Liggett is the Founder and Chief Executive Officer of Liggett Advisors, a strategy/implementation consulting business. She served as presidenta business coach and chief executive officerconsultant for Stanford Seed from 2017 to 2018. She was President and Chief Executive Officer of NovaTorque, Inc., a manufacturer of high-efficiency electric motor systems, from 2009 until late 2016, when it was acquired by Regal Beloit. She previously served as presidentPresident and chief executive officerChief Executive Officer of Apexon, Inc., a provider of supply chain optimization software solutions for global manufacturers, from 2004 to 2007. Ms. Liggett served as presidentPresident and chief executive officerChief Executive Officer of Capstone Turbine Corporation (provider of microturbine systems for clean, continuous distributed energy generation) from 2002 to 2003 and, prior to that, held various management and executive roles at Raychem Corporation (acquired by Tyco International in 1999) from 1984 to 2001, including corporate vice presidentCorporate Vice President of Raychem and managing directorManaging Director of Tyco Ventures. Ms. Liggett is presently a director of Materion Corporation since 2020, and of Kaiser Aluminum since 2018. She was a director of MTS Systems Corporation from 2010 to 2016 and was a director of Immersion Corporation from 2005 to 2011. She also currently servesserved on the Purdue University School of Engineering Advisory Board.Board from 2000 until 2018. Ms. Liggett holds a bachelorBachelor of scienceScience degree in chemical engineeringChemical Engineering from Purdue

University, a master’sMaster of scienceScience degree in engineeringEngineering and manufacturing systemsManufacturing Systems from Stanford University and a master’sMaster’s degree in business administrationBusiness Administration from the Stanford University Graduate School of Business. Ms. Liggett’s qualifications to serve on our Board of Directors include her chief executive officerChief Executive Officer and management experience in a variety of technical industrial companies. She has managed worldwide businesses, partnerships, and international joint ventures. She also has public company and private company operating and board experience, and expertise in strategy, operations, new product development, sales, marketing, and business development for highly technical businesses.

Thomas T. Edman has served as a director of Ultra Clean since June 2015. Mr. Edman has served as the Chief Executive Officer of TTM Technologies, Inc. since January 2014, as its President since January 2013 and as a member of its boardBoard of directorsDirectors since September 2004. From early 2011 to December 2012, Mr. Edman served as Group Vice President and General Manager of the AKT Display Business Group, which is a division of Applied Materials Inc., a publicly held provider of nanomanufacturing technology solutions. From 2006 to 2011, Mr. Edman served as Corporate Vice President of Corporate Business Development of Applied Materials, Inc. Prior to that, Mr. Edman served as President and Chief Executive Officer of Applied Films Corporation from May 1998 until Applied Materials, Inc. acquired Applied Films Corporation in July 2006. From June 1996 until May 1998, Mr. Edman served as Chief Operating Officer and Executive Vice President of Applied Films Corporation. From 1993 until joining Applied Films, Mr. Edman served as General Manager of the High Performance Materials Division of Marubeni Specialty Chemicals, Inc., a subsidiary of a major Japanese trading corporation. Mr. Edman presently serves on the boardBoard of directorsDirectors of the IPC, an electronic industry association.association and serves on the Executive Committee as Secretary and Treasurer. Mr. Edman previously served as Chairman

and as a member of the boardBoard of directorsDirectors of FlexTech, formerly the United States Display Consortium and the AeA (American Electronics Association). Mr. Edman holds a Bachelor of Arts degree in East Asian studiesStudies (Japan) from Yale University and a Master’s degree in Business Administration from The Wharton School at the University of Pennsylvania. Mr. Edman was nominated to the boardBoard of directorsDirectors because of his business acumen and experience in the technology industry, having served in numerous senior executive roles with sizeable technology companies, including as the chief executive officerChief Executive Officer of a public company. Mr. Edman also has extensive experience in Asia and with compensation-related matters.

Barbara V. Scherer has served as a director of Ultra Clean since June 2015. Ms. Scherer has served as a member of the boardBoard of directorsDirectors of NETGEAR, Inc., a global networking company that delivers innovative products to consumers, businesses and service providers, since August 2011 and as a member of the boardBoard of directorsDirectors of ANSYS, Inc., a publicly traded engineering simulation software and services company, since April 2013. Ms. Scherer was Senior Vice President, financeFinance and administrationAdministration and chief financial officerChief Financial Officer of Plantronics, Inc., a global leader in audio communication devices for businesses and consumers, from 1998 to 2012. In this position, she was responsible for all aspects of the company’s financial management, as well as information technology, legal and investor relations. She was Vice President, financeFinance and administrationAdministration and chief financial officerChief Financial Officer of Plantronics from 1997 to 1998. Prior to Plantronics, Ms. Scherer held various executive management positions spanning eleven11 years in the disk drive industry, was an associate with The Boston Consulting Group, and was a member of the corporate finance team at ARCO in Los Angeles. From 2004 through 2010, she served as a director of Keithley Instruments, Inc., a publicly traded test and measurement company, until its acquisition by Danaher Corporation. She also has experience serving on the boards ofnon-profit organizations. Ms. Scherer received B.A. degreesa Bachelor of Arts degree from the University of California at Santa Barbara and her M.B.A.Master’s degree in Business Administration from the School of Management at Yale University. With a career spanning more than 30 years including 25 years in senior financial leadership roles in the technology industry, Ms. Scherer provides the Company with practical and strategic insight into complex financial reporting and management issues as well as significant operational expertise.

Ernest E. Maddock has served as a director of Ultra Clean since June 2018. Mr. Maddock has held leadership positions at multiple global companies during his career. From 2015 through his recent retirement, he served as Senior Vice President and Chief Financial Officer of Micron Technology. Prior to joining Micron, Mr. Maddock served as Executive Vice President and Chief Financial Officer of Riverbed Technology. Prior to Riverbed, he spent 15 years at Lam Research Corporation (“Lam”), rising to Executive Vice President and Chief Financial Officer in 2008 and serving in that role until April 2013. His previous roles at Lam included Vice President, Customer Support Business Group; and Group Vice President and Senior Vice President of Global Operations. Mr. Maddock also served as a member of the Board of Directors for Intersil Corporation from July 2015 to February 2017. Mr. Maddock holds a Bachelor of Science degree in Industrial Management from the Georgia Institute of Technology and a Master’s degree in Business Administration from Georgia State University. Mr. Maddock was nominated to the Board of Directors because he provides the Company with practical and strategic insight into complex financial reporting and management issues as well as significant operational expertise.

Jacqueline A. Seto has served as a director of Ultra Clean since January 2020. Ms. Seto spent 22 years at Lam Research Corporation (“Lam”) from 1994 until 2016. During that time, she served as Group Vice President and General Manager of the Cleans Product Group at Lam from August 2011 until November 2015. Prior to this position, her previous roles at Lam included Corporate Vice President and General Manager in the Reliant Business Unit from April 2009 to August 2011, Vice President of Product and Strategic Marketing from November 2007 to March 2009, and Managing Director of Emerging Businesses from August 2003 until November 2007. Since 2016, Ms. Seto has served as Principal at Side People Consulting, partnering with well-established corporate and emerging companies and with non-profit organizations advising on strategic and business planning, change management and other executive service consulting. Ms. Seto holds a Bachelor of Engineering in Chemical Engineering from McGill University in Quebec. Ms. Seto currently serves as a member of the Board of Trustees for The Oregon Museum of Science and Industry (OMSI) since January 2018, as a

member of the Board of Directors for Masterranking.com since April 2015, and as a member of the Board of Directors for International Women’s Forum Oregon since August 2020. She previously served as a member of the Board of Directors for TriAegis Residential Services from June 2001 until April 2007 and as the Board Secretary for Prevent Child Abuse Oregon (PCAO) from October 2017 until February 2021. Ms. Seto was nominated to the Board of Directors because her deep understanding of the semiconductor industry and her proven experience in strategic thinking adds a valuable voice to the Company’s long and short term business planning.

There are no family relationships among any of our directors and executive officers. There are no arrangements or understandings between any of our directors and us pursuant to which such director was or is to be selected as a director or nominee. Information related to the compensation of our Board of Directors can be found under “—Director Compensation” below.

Board Recommendation

Our Board of Directors recommends that you vote “FOR” each of the nominees to the Board of Directors set forth in this Proposal 1.

Structure of Board of Directors and Corporate Governance Information

Director IndependenceIndependence. . We are required to comply with the director independence rules of the Nasdaq Stock Market (“Nasdaq”) and the SEC. These rules require that the board of directors of a listed company be composed of a majority of independent directors and that the audit committee, compensation committee and nominating and corporate governance committee be composed solely of independent directors.

Our Board of Directors has determined that each of our directors and director nominees is independent in accordance with applicable Nasdaq and SEC rules other than Messrs. Mezhvinsky andMr. Scholhamer. Accordingly, a majority of our current Board of Directors is independent as required by Nasdaq rules and, upon election of each of our director nominees at the 20182021 Annual Meeting of Stockholders, a majority of our Board of Directors will be independent as required by Nasdaq rules.

Director ResponsibilitiesResponsibilities.. We are governed by our Board of Directors and its various committees that meet throughout the year. Our Board of Directors currently consists of seven directors.eight directors after Ms. Seto was elected to serve as a director effective January 1, 2020. During 2017,2020, there were 13seven meetings of our Board of Directors. We expect directors to attend and prepare for all meetings of the Board of Directors and the meetings of the committees on which they serve. Each of our directors attended more than 75% of the aggregate number of meetings of the Board of Directors and the committees on which he or she served during 2017.2020.

Board Leadership StructureStructure.. Our corporate governance guidelines allow for the flexibility to combine or separate the offices of chairmanChairman and the chief executive officerChief Executive Officer to best serve the interests of the Company and its stockholders. Mr. Scholhamer serves as the chief executive officerChief Executive Officer of the Company and Mr. Granger serves as the chairmanChairman of our Board of Directors. Our Board of Directors believes our current board leadership structure to be an efficient and successful leadership model for the Company, promoting clear accountability and effective decision-making. The roles of our Chairman and Chief Executive Officer are separated to allow Mr. Scholhamer to develop and execute on our corporate strategy and focus onday-to-day operations and company performance. Our Board of Directors believes that our stockholders benefit from Mr. Granger’s service as Chairman due to his deep background and experience in our industry and his knowledge of our operations as our former chief executive officer.Chief Executive Officer. Our Board of Directors recognizes that a different leadership model may be warranted under different circumstances. Accordingly, our Board of Directors periodically reviews its leadership structure.

The Board also continually reviews the need for effective independent oversight. Each member of each of our Board of Director’s standing committees is an independent director, and each independent director is actively

involved in independent oversight. Our independent directors meet in executive session during each regularly scheduled quarterly meeting of our Board of Directors and periodically evaluate both our Chairman and our Chief Executive Officer.Officer as well as Board and committee performance. All directors have unrestricted access to management at all times and frequently communicate with the Chairman, the Chief Executive Officer and other members of management on a variety of topics. Given the above factors, our Board of Directors has historically determined that our leadership structure is appropriate.

Corporate GovernanceGovernance.. Our Board of Directors has adopted corporate governance guidelines. These guidelines address items such as the qualifications and responsibilities of our directors and director candidates and the corporate governance policies and standards applicable to us in general. In addition, we have adopted a code of business conduct and ethics that applies to all officers, directors and employees. Our corporate governance guidelines and our code of business conduct and ethics as well as the charters of the Nominating and Corporate Governance Committee, Audit Committee and Compensation Committee are available on our website at http://uct.com/investors/corporate-governance/.

Communicating with our Board of DirectorsDirectors.. Any stockholder wishing to communicate with our Board of Directors may send a letter to our Secretary at 26462 Corporate Avenue, Hayward, CA 94545. Communications intended specifically fornon-employee directors should be sent to the attention of the chair of the Nominating and Corporate Governance Committee.

Annual Meeting AttendanceAttendance.. Our Board of Directors has adopted a policy that all members should attend each annual meeting of stockholders when practical. SixEight of our seventhen nine incumbent directors attended the 20172020 Annual Meeting of Stockholders.

Risk Oversight

Our Board of Directors plays an active role, as a whole and also at the committee level, in overseeing the management of our risks. Our Board of Directors regularly reviews reports from the management team on areas of material risk to the Company, including operational, financial, legal and strategic risks. Each of the committees of our Board of Directors also oversees the management of company risks that fall within the committee’s areas of responsibility. The Audit Committee periodically reviews risks associated with financial reporting and internal controls, as well as risks associated with liquidity, customer credit and inventory reserves and insurance coverage.reserves. The Nominating and Corporate Governance Committee assists the Board in overseeing risks associated with board organization, membership, structure and corporate governance. The Compensation Committee assists the Board in reviewing whether any material risks arise from our compensation programs and in overseeing risks associated with succession planning for our executives. The Board also reviews our director and officer insurance annually.

Environmental, Human Capital, Social and Governance Considerations

The Company is committed to building customer trust on a foundation of competent personnel and suppliers, discipline to address customer requirements, robust business processes, governance and accountability and rapid and thorough problem solving, supported by a culture that emphasizes leadership, open and honest communication, prevention over reaction, training and mentoring, a strong governance system and a positive reward system. We apply our core values to work to build a responsible and sustainable end-to-end supply chain, ensure employee health and safety in the workplace, foster an atmosphere of acceptance, inclusion, trust and mutual respect in the workplace, promote employee engagement inside and outside the company and give back to communities. We are committed to efficient company management, protection of stockholders’ interests and transparency of corporate communications.

It is our policy to pursue our worldwide operations in a safe, socially and environmentally responsible manner that protects the health and wellbeing of our employees, our customers and the communities where we

operate while respecting the environment. Our operations are subject to federal, state and local regulatory requirements and foreign laws relating to environmental, waste management and health and safety matters, including measures relating to the release, use, storage, treatment, transportation, discharge, disposal and remediation of contaminants, hazardous substances and waste, as well as practices and procedures applicable to the construction and operation of our facilities.

Environmental:

Human Capital:

Social Responsibility:

Governance:

Committees of ourOur Board of Directors

Our Board of Directors has three principal committees. The following describes each committee’s current membership, the number of meetings held during 20172020 and its mission:

Audit CommitteeCommittee.. Among other matters, the Audit Committee is responsible for:

A copy of the Audit Committee’s charter is available on our website at http://uct.com/investors/corporate-governance/.

The current members of the Audit Committee are Ernest E. Maddock (chair), Barbara V. Scherer, (chair), Thomas T. Edman and David T. ibnAle. Our Board of Directors has determined that each member of the committee satisfies both the SEC’s

additional independence requirement for members of audit committees and the other requirements of Nasdaq for members of audit committees. The Board of Directors has also concluded that each member of the Audit Committee qualifies as an audit committee financial expert as defined by SEC rules and has the financial sophistication required by Nasdaq. The Audit Committee met fivefour times in 2017.2020.

Compensation CommitteeCommittee.. Among other matters, our Compensation Committee:

A copy of the Compensation Committee’s charter is available on our website at http://uct.com/investors/corporate-governance/. The Compensation Committee’s process for deliberations on executive compensation is described below under “Compensation Discussion and Analysis.”

As part of our oversight of our executive compensation program and in conjunction with the Compensation Committee, we consider the impact of our executive compensation program and the incentives created by different elements of the executive compensation program on our risk profile. In addition, we review all of our compensation policies and procedures, including the incentives that they create and factors that affect the likelihood of excessive risk-taking, to determine whether they present a significant risk to the Company. Based on this review, we have concluded that our compensation policies and procedures are not reasonably likely to have a material adverse effect on the Company.

The current members of the Compensation Committee are Thomas T. Edman (chair), David T. ibnAle, (chair), Thomas T. Edman and Emily M. Liggett.Liggett and Jacqueline A. Seto. Our Board of Directors has determined each member of the committee is independent as defined under Nasdaq and SEC rules. The Compensation Committee met sixseven times in 2017.2020.

Nominating and Corporate Governance CommitteeCommittee.. Among other matters, our Nominating and Corporate Governance Committee:

A copy of the Nominating and Corporate Governance Committee’s charter is available on our website at http://uct.com/investors/corporate-governance/.

The current members of the Nominating and Corporate Governance Committee are Emily M. Liggett (chair), Thomas T. Edman and Barbara V. Scherer.Scherer and Ernest E. Maddock. Our Board of Directors has determined that each member of the Nominating and Corporate Governance Committee is independent as defined under Nasdaq. The Nominating and Corporate Governance Committee met four times in 2017.2020.

Consideration of Director Nominees

Director QualificationsQualifications.. The Nominating and Corporate Governance Committee of the Board operates pursuant to a written charter and establishes membership criteria for the Board and each committee of the Board and recommends to the Board individuals for membership on the Board and its committees. There is no fixed set of qualifications that must be satisfied before a candidate will be considered. Rather, candidates for director

nominees are reviewed in the context of the current composition of our Board of Directors, our operating requirements and the interests of our stockholders. In conducting its assessment, the committee considers issues of judgment, diversity, age, skills, background, experience and such other factors as it deems appropriate given the needs of the Company and our Board of Directors. Although we do not have a formal policy with regard to the consideration of diversity, when identifying and selecting director nominees, the Nominating and Corporate Governance Committee also considers the impact a nominee would have in terms of increasing the diversity of our Board of Directors with respect to professional experience, skills, backgrounds, viewpoints and areas of expertise. The Nominating and Corporate Governance Committee also considers the independence, financial literacy and financial expertise standards required by our committee charters and applicable laws, rules and regulations, and the ability of the candidate to devote the time and attention necessary to serve as a director and a committee member.

Identifying and Evaluating Nominees for DirectorDirector.. In the event that vacancies are anticipated or otherwise arise, the Nominating and Corporate Governance Committee (or, if the Nominating and Corporate Governance Committee is not comprised solely of independent directors, our independent directors) considers various potential candidates for director. Candidates may come to the attention of the Nominating and Corporate Governance Committee (or our independent directors) through current directors, professional search firms engaged by us, stockholders or other persons. Candidates are evaluated at regular or special meetings of the Nominating and Corporate Governance Committee (or our independent directors) and may be considered at any point during the year.

Stockholder NomineesNominees.. Candidates for director recommended by stockholders will be considered by the Nominating and Corporate Governance Committee (or our independent directors).Committee. Such recommendations should include the candidate’s name, home and business contact information, detailed biographical data, relevant qualifications for membership on our Board of Directors, information regarding any relationships between the candidate and our Company within the last three years and a written indication by the recommended candidate of the candidate’s willingness to serve on our Board of Directors. Stockholder recommendations, with such accompanying information, should be sent to the attention of the Chair of the Nominating and Corporate Governance Committee at the address listed under “Information Concerning Solicitation and Voting—Contacting Ultra Clean.”

Stockholders also may nominate directors for election at our annual meeting of stockholders by following the provisions set forth in our Amended and Restated Bylaws. The deadline and procedures for stockholder nominations are disclosed elsewhere in this proxy statement under the caption “Information Concerning Solicitation and Voting—Deadline for Receipt of Stockholder Proposals.”

Director Compensation

For fiscal 2017, eachOur non-employee director was paid directors earn the following annual retainers for service on our Board of Directors and its standing committees:

No fee is paid for attendance at any Board of Directors or committee meeting. Cash retainers for Board and committee service are paid quarterly.

Annual Stock Awards

On an annual basis, each non-employee director is eligible to serve on such committee), and a $30,000receive an annual cash fee for serving as Chairmanaward of the Board.restricted stock. On the date of our 20172020 annual meeting of stockholders, each of our non-employee directordirectors at such time was granted a restricted stock award for 7,500with a value of approximately $130,000 (equating to 6,301 shares of our common stock based on the closing price of our common stock on the business day immediately prior to the grant date) that fully vests on the earlier of (i) the day before the 20182021 Annual Meeting of Stockholders and (ii) June 2, 2021. Ms. Seto, who was appointed to the Board effective January 1, 2020, was granted a restricted stock award for 2,256 shares of our common stock that fully vested on May 24, 2018.23, 2020.

Initial Stock Awards

Upon joining the Board (other than at an annual meeting), each non-employee director is eligible to receive an initial award of restricted stock, in an amount equal to the value of the annual non-employee director award for such year, pro-rated based on the length of services provided from appointment to the Board until the following annual stockholder meeting. The restricted stock will become fully vested on the date of the annual stockholder meeting following such award.

The following table sets forth compensation for ournon-employee directors for fiscal 2017:2020. Our only employee director during fiscal 2020, Mr. Scholhamer, does not receive separate compensation for service as a director. Information on Mr. Scholhamer’s compensation for fiscal 2020 is disclosed in the Summary Compensation Table below.

The Board of Directors has also adopted stock ownership guidelines for our Chief Executive Officer. The policy was amended in February 2020 to provide that our Chief Executive Officer should hold common stock with a value at least 3X his or her base salary, and that he or she be allowed three years from the date such person becomes our Chief Executive Officer to accumulate such number of shares of our common stock. The amendment to the policy was intended to bring it in line with more contemporary governance and peer practices. Our current Chief Executive Officer is currently in compliance with our stock ownership guidelines.

The Company’s Insider Trading Policy, which can be found on our website, provides that our securities shall not be made subject to hedge transactions or puts and calls. The Insider Trading Policy further prohibits any pledges of our securities by our directors and executive officers.

Payments to Compensation Consultant and its Affiliates

In April 2016, theThe Compensation Committee determined to engage Radford (“Radford”), a part of Aon plc,Semler Brossy, with respect to fiscal 20172020 executive officer andnon-employee director compensation matters. RadfordSemler Brossy was retained by our Compensation Committee to provide an independent review of the Company’s executive compensation programs, including an analysis of both the competitive market and the design of the programs for

2017. 2020. In addition, during 2017, Radford2020, Semler Brossy assisted the Compensation Committee with its CEO pay ratio analysis and its evaluation of the risks associated with our compensation programsits executive severance and change in control policies and provided our Compensation Committee with a director compensation assessment and assistance in developing our Compensation Discussion and Analysis in this proxy statement. RadfordSemler Brossy also furnished the Compensation Committee with reports on peer company practices relating to the following matters: short-term and long-term compensation program design; equity compensation; retention value of current equity holdings; target incentive opportunities; and compensation trends for board and committee members. We incurred $34,000 and $60,000 in fees for Radford’s work in fiscal years 2016 and 2017, respectively.trends. For further discussion of the work conducted by RadfordSemler Brossy as our compensation consultant, see “Compensation Discussion and Analysis—Process for Determining Executive Compensation.”

Certain Relationships and Related Party Transactions

Transactions with DirectorsDirectors.. The Company leases a facility from an entity controlled by Leonid Mezhvinsky, one of our former directors. In the year ended December 29, 2017,25, 2020, we incurred rent and other expenses resulting from the lease of this facility of approximately $322,000.$438,000.

Related Person Transaction PolicyPolicy.. Our written Related Person Transaction Policy requires our Board of Directors or the Nominating and Corporate Governance Committee to review and approve all related person transactions. Our directors and officers are required to promptly notify our Chief Compliance Officer (which is currently the Chief Financial Officer)our General Counsel) of any transaction which potentially involves a related person. Our Board of Directors or the Nominating and Corporate Governance Committee then considers all relevant facts and circumstances, including without limitation the commercial reasonableness of the terms of the transaction, the benefit and perceived benefit, or lack thereof, to the Company, opportunity costs of alternate transactions, the materiality and character of the related person’s direct or indirect interest, and the actual or apparent conflict of interest of the related person. Our Board of Directors or the Nominating and Corporate Governance Committee will not approve or ratify a related person transaction unless it has determined that, upon consideration of all relevant information, the transaction is in, or not inconsistent with, the best interests of the Company and its stockholders.

Other than as disclosed above, since December 27, 2019, we have not entered into any transactions, nor are there any currently proposed transactions, between us and a related party where the amount involved exceeds, or would exceed, $120,000, and in which any related person had or will have a direct or indirect material interest.

PROPOSAL 2: RATIFICATION OF THE APPOINTMENT OF OUR INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Audit Committee has appointed Moss Adams LLP (“Moss Adams”) to serve as our independent registered public accounting firm for fiscal 2018.2021. We are asking you to ratify this appointment. Ratification of the appointment of Moss Adams as our independent registered public accounting firm for fiscal 20182021 requires the affirmative vote of the holders of a majority of our common stock present in person or represented by proxy at the annual meeting and entitled to vote thereon. Abstentions will have the same effect as negative votes for this proposal. Although ratification is not required for us to retain Moss Adams, in the event of a majority vote against ratification, the Audit Committee may reconsider its selection. Even if the appointment is ratified, the Audit Committee may, in its discretion, direct the appointment of a different independent registered public accounting firm at any time during the year if the Audit Committee determines that such a change would be in the Company’s and its stockholders’ best interests. A representative of Moss Adams is expected to be present at the annual meeting of stockholders, will have the opportunity to make a statement if he/she desires to do so and is expected to be available to respond to appropriate questions.

Audit Fees

Set forth below are the aggregate audit fees incurred for the professional services provided by Moss Adams and its affiliates in fiscal 20172020 and fiscal 2016.2019.

Audit fees consist of fees billed, or to be billed, for services rendered to us and our subsidiaries for the audit of our annual financial statements and internal control over financial reporting, reviews of our quarterly financial statements included in our quarterly reports on Form10-Q and audit services provided in connection with other statutory and regulatory filings. Audit fees decreased in 2020 primarily as a result of decreased hours associated with our Services division. Audit related fees for 2020 consisted of fees billed for services rendered to us for employee benefit plans. Audit related fees for 2019 consisted of fees billed for services rendered to us for employee benefit plans and acquisition-related due diligence activity.

Preapproval Policy of Audit Committee of Services Performed by Independent Auditors

The Audit Committee’s policy requires that the committee preapprove audit andnon-audit services to be provided by our independent auditors before the auditors are engaged to render services. The Audit Committee may delegate its authority topre-approve services to one or more Audit Committee members; provided that such designees present any such approvals to the full Audit Committee at the next Audit Committee meeting.

All services described above werepre-approved in accordance with the Audit Committee’spre-approval policies.

Board Recommendation

Our Board of Directors recommends that you vote “FOR” ratification of the appointment of Moss Adams LLP as our independent registered public accounting firm for fiscal 2018.2021.

REPORT OF THE AUDIT COMMITTEE

REPORT OF THE AUDIT COMMITTEE OF THE BOARD OF DIRECTORS

Notwithstanding any statement to the contrary in any of our previous or future filings with the Securities and Exchange Commission, this report of the Audit Committee of our Board of Directors shall not be deemed “filed” with the Securities and Exchange Commission or “soliciting material” under the Securities Exchange Act of 1934, as amended, and shall not be incorporated by reference into any such filings.

The Audit Committee, which currently consists of Ernest E. Maddock, Barbara V. Scherer, Thomas T. Edman and David T. ibnAle, evaluates audit performance, manages relations with our independent registered public accounting firm and evaluates policies and procedures relating to internal accounting functions and controls. The key responsibilities of our Audit Committee are set forth in our Audit Committee’s charter, which is available on our website athttp://uct.com/investors/corporate-governance/. This report relates to the activities undertaken by the Audit Committee in fulfilling such responsibilities.

The Audit Committee members are not professional auditors, and their functions are not intended to duplicate or to certify the activities of management and the independent registered public accounting firm. The Audit Committee oversees our financial reporting process on behalf of our Board of Directors. Our management has the primary responsibility for the financial statements and reporting process, including our systems of internal controls over financial reporting. In fulfilling its oversight responsibilities, the Audit Committee reviewed and discussed with management the audited financial statements included in the Annual Report on Form10-K for the year ended December 29, 2017.25, 2020. This review included a discussion of the quality and the acceptability of our financial reporting and internal control over financial reporting, including the clarity of disclosures in the financial statements.

The Audit Committee also reviewedhas discussed with ourthe independent registered public accounting firm, who is responsible for expressing an opinion onauditors the conformity of our audited financial statements with generally accepted accounting principles, their judgments as to the quality and the acceptability of our financial reporting and such other matters required to be discussed withby the Audit Committee under generally accepted auditing standards in the United States including Auditing Standard No. 16,Communications with Audit Committees, as adopted byapplicable requirements of the Public Company Accounting Oversight Board (the “PCAOB”(“PCAOB”). and the Commission. The Audit Committee has received the written disclosures and the letter from the independent registered public accounting firm required by applicable requirements of the PCAOB regarding the independent accountant’s communications with the Audit Committee concerning independence. The Audit Committee discussed with the independent registered public accounting firm such auditors’ independence from management and Ultra Clean, including the matters in such written disclosures required by applicable requirements of the PCAOB regarding the independent accountant’s communications with the Audit Committee concerning independence.

The Audit Committee further discussed with our independent registered public accounting firm the overall scope and plans for their audits. The Audit Committee meets periodically with the independent registered public accounting firm, with and without management present, to discuss any significant matters regarding internal control over financial reporting that have come to their attention during the audit, and to discuss the overall quality of our financial reporting.

In reliance on the reviews and discussions referred to above, the Audit Committee recommended to our Board of Directors and our Board of Directors approved that the audited financial statements and disclosures under “Management’s Discussion and Analysis of Financial Condition and Results of Operations” be included in the Annual Report on Form10-K for the year ended December 29, 2017,25, 2020, as filed with the Securities and Exchange Commission on March 14, 2018.February 23, 2021.

Members of the Audit Committee

Ernest E. Maddock, Chair

Barbara V. Scherer Chair

Thomas T. Edman

David T. ibnAle

PROPOSAL 3: ADVISORY VOTE APPROVING THE COMPENSATION OF THE NAMED EXECUTIVE OFFICERS

This proposal provides you with an opportunity to cast anon-binding, advisory vote approving the fiscal 20172020 compensation of our named executive officers as disclosed pursuant to the compensation disclosure rules of the SEC in this proxy statement, including the “Compensation Discussion and Analysis,” the compensation tables and other narrative executive compensation disclosures. AtIn a decision that factored in the non-binding advisory vote of our stockholders held at our 2017 Annual Meeting of Stockholders on the frequency of stockholder advisory votes on executive compensation, we adopted a proposaldetermined to hold anon-binding, advisory vote on executive compensation annually and are required to do so until ourannually. Our nextnon-binding, advisory vote on the frequency of stockholder advisory votes on executive compensation which is required to occur no later than our 2023 Annual Meeting of Stockholders.

As described in detail under the heading “Compensation Discussion and Analysis,” our executive compensation programs are designed to attract, motivate and retain our named executive officers, who are critical to our success. Under these programs, our named executive officers are rewarded for the achievement of specific short-term and long-term goals. We believe our 20172020 executive compensation is appropriate. Please see the “Compensation Discussion and Analysis” beginning on page 1823 for additional details about our executive compensation philosophy and programs, including information about the fiscal 20172020 compensation of our named executive officers. This advisory vote is not intended to address any specific item of compensation, but rather the overall compensation principles and practices and the fiscal 20172020 compensation of our named executive officers.

As an advisory vote, this proposal is not binding on us or our Board of Directors. The Compensation Committee and our Board of Directors value the opinions of the stockholders and will consider the outcome of the vote when making future compensation decisions.

Board Recommendation

Our Board of Directors recommends that you vote “FOR” the approval of the non-binding advisory vote on compensation of theour named executive officers for fiscal 20172020 as disclosed pursuant to the compensation disclosure rules of the SEC, which disclosure includes the “Compensation Discussion and Analysis,” the compensation tables and other narrative executive compensation disclosures in this proxy statement.

EXECUTIVE OFFICER COMPENSATION

Compensation Discussion and Analysis

The Compensation Discussion and Analysis, or CD&A, describes and analyzes our executive compensation philosophy and program in the context of the compensation paid during 2017,2020, the last fiscal year, to our chief executive officer, our chief financial officer,Chief Executive Officer, Chief Financial Officer, and each of our three other highest paid executive officers (collectively referred to as our named executive officers). Our named executive officers for fiscal 2017 are:2020 were:

Biographical information regarding these officers is set forth in our Annual Report on Form10-K filed with the SEC on March 14, 2018. Mr. Scholhamer’s biography is also set forth above with our other directors.

Fiscal 2017 Key Financial2020 Performance and Share PerformanceCompensation Highlights

As a general principle, it isDespite the Company’s goaladverse impacts and uncertainty caused by the COVID-19 pandemic, we were able to tiedeliver strong financial and market performance and maintain the Company’s performance closely with executive compensation. Therefore, in orderdesign of our in-flight incentive programs without having to provide proper context regarding the Company’s compensation practices and their correlation to themake any COVID-related program adjustments.

Performance Highlights:

The Company’s overall performance was very strong in 2020. We ended 2020 with total revenue of $1.4 billion, operating margin of 11.3% and earnings per share of $2.80. We believe we have continuously adjusted to the table below provideschanging work environment while staying focused on meeting customer demand and delivering strong return to shareholders. Higher volumes, coupled with a focus on operational efficiencies and a favorable product mix, resulted in improved profitability for fiscal year 2020 as compared to fiscal year 2019.

The following is a summary of key highlights of the Company’s financial and share performance for fiscal year 2017.2020.

These financial highlights demonstrate significant improvements

Compensation Highlights:

Governance and Executive Pay Policies and Practices

The Company is committed to responsible executive compensation and governance practices that support our business and talent strategies to compete in the semiconductor industry while also aligning with prevailing governance practices. The following list contains items that we believe are in the shareholder’s best interest and practices that we avoid due to the compensation paid to our named executive officers in 2017 as described below was aligned with the Company’s significantly improving performance.potential for a misalignment between pay and performance:

Overview of Compensation Program and Philosophy

OurAs a general principle, the Company seeks to tie executive compensation program, which is established byclosely with the Company’s performance. When assessing our compensation programs, our Compensation Committee is intended to meetrelies on three principal long-term objectives:guiding principles:

2.

motivate Motivate key employees to achieve short-termgoals using individual goals combined with a balanced scorecard approach at the corporate, business unit and long-term corporate goalsoperational levels that enhance stockholder value;value. For 2020, these corporate goals track with our longer-term objective of profitable growth and market share gains. And specific to 2020, our corporate goals also addressed the integration of newly-acquired businesses, including the integration of key talent.

To meet these objectives, we have historically adopted the following overriding long-term compensation policies:

Our Compensation Committee considers these policies in determining the appropriate allocation of base salaries, annual cash incentive compensation, long-term equity-based compensation and other benefits. Other considerations include our business objectives and environment, fiduciary and corporate responsibilities (including internal equity considerations and affordability), competitive practices and trends, regulatory requirements, and the mitigation of risks associated with these policies. Like most companies, we use a combination of fixed and variable compensation programs to reward and incentivize strong performance, as well as to align the interests of our executive officers with those of our stockholders. In determining the particular elements of compensation that will be used to implement our overall compensation policies, the Compensation Committee takes into consideration a number of factors related to corporate and individual performance, as further described below, as well as competitive practices among our peer group.

In 2017, after comparing the revenue, profitability, operating income, market capitalizationOur Board of Directors and certain other metricsCompensation Committee have a long-standing practice of our Company relative to other members of the 2017 Peer Group (described below), our compensation committee determined to revise its long-term compensation philosophy to generally target, on a long-term basis,targeting compensation at or around the 50th percentilemidrange of comparable companies for each element of our compensation program. Our long-term goal in prior years was to target total compensation, including base salaries, cash incentive awards and equity awards near the 50th percentile among similar companies, of which total cash compensation (including base pay and annual cash incentives) was targeted between the 25th and 50th percentile of such companies, and time and performance-based equity awards historically was targeted between the 50th and 75th percentile among such companies. We believeThe Compensation Committee believes that targeting overall, and each element of, compensation at or around the 50th percentilemidrange of peer compensation will enable us to remain competitive in attracting and retaining qualified executive officers while avoiding paying amounts in excess of what we believe is necessary to attract and retain such executive officers. Our Compensation Committee also retains the discretion to target compensation for specific individuals based on a variety of additional factors, including Company and individual performance.

Process for Determining Executive Compensation

Each year, our Compensation Committee, together with our senior management team, establishes performance targets for short-term and long-term incentive plans that require the achievement of significant financial results. Each year, our Compensation Committee determines compensation by assessing prior year performance against these established financial targets, as well as other factors such as the compensation paid by comparable companies (which may include comparisons to companies in broad-based compensation surveys or, for fiscal 2017,2020, our 2017 Peer Group), achievement of strategic objectives, improvements in market share and the professional development and potential of individual officers. Ultimately, the amount of compensation awarded to our executive officers is determined based on performance and what our Compensation Committee believes is in the best interests of our stockholders.

The Compensation Committee meets with our chief executive officerChief Executive Officer and other executives, including our senior vice presidentSenior Vice President of human resources,Human Resources, as necessary, to obtain recommendations with respect to Company compensation programs, practices and packages. The chief executive officer,Chief Executive Officer, in consultation with our senior vice presidentSenior Vice President of human resources,Human Resources, develops recommendations that he makes to the Compensation Committee on executive performance, base salary, annual bonus targets and equity compensation for the executive team and other employees, other than himself. Our senior vice presidentSenior Vice President of human resourcesHuman Resources also meets directly with the Compensation Committee (including outside the presence of our chief executive officer)Chief Executive Officer) to assist the Compensation Committee in its decision-making process, including its analysis of broad-based data from third-party industry surveys and other data on executive compensation. Although the Compensation Committee considers management’s recommendations with respect to executive compensation, the Compensation Committee makes all final decisions on executive compensation matters.

Our chief executive officerChief Executive Officer and senior vice presidentSenior Vice President of human resourcesHuman Resources attend most of the Compensation Committee’s meetings, but the Compensation Committee also holds executive sessions not attended by any members of management ornon-independent directors. The Compensation Committee deliberates and makes decisions with respect to performance and compensation without the chief executive officerChief Executive Officer and the Company’s other executives present. The Compensation Committee has the ultimate authority to make decisions with respect to the compensation of our executive officers, but may, if it chooses, delegate some of its responsibilities to subcommittees. The Compensation Committee has not in the past delegated authority with respect to the compensation of executive officers. The Compensation Committee has delegated to the chief executive officer the authority to grant equity awards to employees below the level of corporate vice president under guidelines approved by the Compensation Committee and to make salary adjustments and short-term bonus decisions for employees (other than executive officers) under guidelines approved by the Compensation Committee.

The Compensation Committee engaged RadfordSemler Brossy as its outside compensation consultant in April 20162019 to provide an independent review of the Company’s executive compensation program and recommend a course of action for fiscal year 2017,2020, including an analysis of both the competitive market and the design of our compensation programs. More specifically, RadfordSemler Brossy advised the Compensation Committee on the designation of peer group companies, evaluated the final list of peer companies approved by the Compensation Committee and provided competitive compensation data and analysis relating to the compensation of our chief executive officerChief Executive Officer and our other executive officers. RadfordSemler Brossy also furnished the Compensation Committee with reports on peer company practices relating to the following matters: short-term and long-term compensation program design; equity compensation; retention value of current equity holdings; target incentive opportunities; and compensation trends for board and committee members.trends. In addition, the Compensation ConsultantSemler Brossy assisted the Compensation Committee with its CEO pay ratio analysis and its evaluation of the risks associated with our compensation programsexecutive severance and change in control policies and provided our Compensation Committee with an assessment ofassistance in developing our directors’ compensation. RadfordCompensation Discussion and Analysis in this proxy statement. Semler Brossy attended meetings of the Compensation Committee regarding executive compensation and also communicated with the chair of the Compensation Committee outside of meetings. The consultant reported to the Committee rather than to management, although the consultant met with management from time to time for purposes of gathering information on proposals that management made or may make to the Compensation Committee. The Compensation Committee has the authority to replace the compensation consultant or hire additional consultants at any time.

RadfordSemler Brossy provides analyses and recommendations that inform the Compensation Committee’s decisions, but it does not decide or approve any compensation decisions. Except for the Company’s subscription to certain broad-based compensation survey data, RadfordSemler Brossy has not provided any services to the Company other than to the Compensation Committee and receives compensation from the Company only for services provided to the Compensation Committee. Our Compensation Committee assessed the independence of RadfordSemler Brossy pursuant to SEC and NASDAQNasdaq rules and concluded that RadfordSemler Brossy is independent and that Radford’sSemler Brossy’s work has not raised any conflict of interest. For a discussion of amounts paid to Radford for executive and director compensation consulting and other services, please see “Payments to Compensation Consultant and its Affiliates” above.

Compensation Structure

The following are the primary elements of our executive compensation program:

Pay Mix.We have selected the foregoing compensation elements because each is considered useful and/or necessary to meet one or more of the principal objectives of our compensation policy. For example, base salary and cash incentive target percentages are set with the goal of attracting employees and adequately compensating and rewarding them for their individual performance, level of responsibility, experience and the Company’s annual financial results, while our equity compensation programs are geared toward providing long-term incentives and rewards for the achievement of long-term business objectives and retaining key talent. We believe that these elements of compensation, when combined, are effective, and will continue to be effective, in achieving the objectives of our compensation program. The charts below depict the allocation of fixed versus “at-risk” pay for the total target compensation for our named executive officers in 2020:

Note: Figures include annualized base salary, target bonus, and grant date fair value of 2020 equity awards.

CEO Target Pay Mix Long Term Equity Incentive 63% Base Salary 19% Short-Term Cash Incentive 19% 81% of Pay 'At Risk' Other NEOs Average Target Pay Mix Long Term Equity Incentive 48% Base Salary 33% Short-Term Cash Incentive 19% 67% of Pay 'At Risk'

The Compensation Committee reviews base salary, cash incentive programs and long-term incentive programs on at least an annual basis. Other programs are reviewed from time to time to ensure that benefit levels remain competitive but are not included in the annual determination of an executive’s compensation package. In setting compensation levels for a particular executive, the Compensation Committee takes into consideration the proposed compensation package as a whole and each element individually, as well as the executive’s past and expected future contributions to our business.

Our Compensation Committee believes that the particular elements of compensation identified above produce a well-balanced mix of both fixed andat-risk compensation that collectively promote retention value and provide each executive officer with both short-term and long-term performance incentives. Base pay provides the executive officer with a measure of security as to the minimum level of compensation he or she will receive while the annual and long-term incentive components motivate the executive officer to focus on the business metrics that will maximize company performance over the long term. Our Compensation Committee believes that this approach will yield increases in stockholder value, provide an appropriate reward for our executive officers, and reduce the risk of loss of executive officers to competitors.

While each element of our compensation program is intended to motivate and encourage employees at all levels to drive performance and achieve superior results for our stockholders, each element is weighted differently for each of our named executive officers based on the employee’s position and ability to impact our financial results. In general, the percentage of performance-based pay, orat-risk pay, or pay based on the performance of the executive against corporate or individual goals, or that is based on the performance of our trading price, increases with job responsibility. This balance is intended to offer an opportunity for gain in the event of successful performance, matched with the prospect of less compensation when performance falls short of established financial and/or stockholder return targets. The table below depicts the allocation of fixed versus “at risk” pay for the total target compensation for our named executive officers in 2017:

Compensation Levels and BenchmarkingMarket Competitiveness.. Overall compensation levelstargets for executive officers are determined based on one or more of the following factors: the individual’s duties and responsibilities within our global Company; the individual’s experience and expertise; the compensation levels for the individual’s peers within our Company; compensation levels for similar positions in our industry or in the technology industry more generally; performance of the individual and our Company as a whole; and the levels of compensation necessary to recruit new executive officers. For fiscal 2017,2020, our Compensation Committee reviewed the compensation of our executive officers and compared it with both that of our 20172020 Peer Group and broader, composite global market survey data provided by Radford.from the Radford Global Technology Survey.

For purposes of fiscal 20172020 compensation decisions, RadfordSemler Brossy advised the Compensation Committee in October 20162019 (based on publicly available data at such time) on the designation of peer group companies, using the following criteria: companies in the semiconductor and semiconductor equipment sectors and technology hardwareelectronic manufacturing services and electronic equipment and instruments industries,non-industry companies with comparable revenues for the trailing 12 months and market capitalization to ours, and other companies selected by shareholder advisory services, as well as other qualitative factors. For the 20172020 Peer Group, the median revenue and market capitalization as of November 2019 was $346.1$602 million and $705.5$1,389 million, respectively, versus $468.3$1,100 million and $229.2$845 million, respectively, for the Company. To develop a competitive market composite for our named executive officers, RadfordSemler Brossy weighted composite market survey data, derived from both peer survey and general technology industry survey data, equally with named peer proxy data.

This resulted in a peer group that included companies which, along with the broader survey data discussed above, were used for benchmarking purposesassessing our competitive market positioning in 20172020 (collectively, the “2017 Peer“Peer Group”) as set forth below:

This peer group is not used for purposes of analyzing the Company’s stock price performance as compared to the NASDAQNasdaq Composite Index and the RDG Semiconductor Composite Index. For further information

regarding the Company’s cumulative total and relative stockholder return, see our graph included in our Annual Report on Form10-K for the year ended December 29, 2017.25, 2020.

As discussed above, our Compensation Committee has a long-term goalpractice of targeting the compensation levels of our executive officers at or around the 50th percentilemedian of the compensation of comparable officers at

comparable companies, as derived from peer group data and broader composite survey data. Our Compensation Committee may vary from this target range for various elements of compensation depending on the executive officer’s job performance, skill set, level of responsibilities, prior compensation and business conditions, or for other reasons. SignificantAny significant variations of our fiscal 20172020 pay decisions as compared to long-term targeted levels are further discussed below.

20172020 Say-on-Pay Results

At our 20172020 Annual Meeting of Stockholders, the stockholders approved, with approximately 98%90% of the votes cast, ournon-binding, advisory vote on our fiscal 20162020 executive compensation program(“say-on-pay”). After considering oursay-on-pay voting results and other factors addressed in the subsequent discussion, the Compensation Committee determined not to make changes to our executive compensation policies and practices as a result of the vote. At our fiscal 2017 Annual Meeting of Stockholders, a majority of the stockholders voted to hold thesay-on-pay vote on an annual basis. Our Board of Directors considered the results of the vote and agreed with the results. Therefore, we are including thesay-on-pay vote in this year’s proxy. Executive compensation decisions for fiscal 20172020 and other details are discussed below in this compensation discussion and analysis.

Cash Compensation

Base salaries and cash incentives are a significant portion of our executive compensation package. We believe this cash compensation helps us remain competitive in attracting and retaining executive talent. Cash incentives are also paid in order to motivate officers to achieve our business goals.

Base Salaries. Base salaries, and any increases or decreases to those levels for each executive officer, are reviewed and approved each year by our Compensation Committee. Such adjustments may be based on factors such as the overall performance of our Company, new roles and responsibilities assumed by the executive officer, the performance of the executive officer’s area of responsibility, the executive officer’s impact on strategic goals, the length of service with our Company, or revisions to or alignment with our long-term compensation philosophy. The Compensation Committee also takes into account the cyclical nature of our business (which results from the industries we serve (in particular the semiconductor industry) being highly cyclical, with recurring periods of over-supply of products) and the state of our industry and the economy in general. However, there is no specific weighting applied to any one factor in setting the level of base salary, and the process ultimately relies on the subjective exercise of our Compensation Committee’s judgment. Although salaries were targeted at or around the 50th percentilemidrange of our peer group for fiscal 2017,2020, our Compensation Committee also takestook into account historical compensation, internal parity with other executives, potential as a key contributor, and special recruiting and retention situations. The 20172020 base salaries for our named executive officers shown in the table below were generally within targeted levels.

In AprilMarch of 2017,2020, our Compensation Committee ultimately approved base salary increases for our named executive officers as set forth in the table below:

The Compensation Committee also determined to increase the base salaries of Ms. Savage, Mr. WilliamsChinnasami, Mr. Bentinck and Mr. SpeirsWilliams by between 2.4% and 4.9% to bettermore closely align their base salaries with market levels, consistent with the Compensation Committee’s long-term compensation philosophy. Mr. Williams’ base salary was consistent with market levels in fiscal 2016, and thus the Compensation Committee determined to award him a 3% increase in base salary consistent with industry survey data on executive compensation for similarly situated executives.

Our base salary levels were also set after considering the significance of the roles of these executives in our overall management for fiscal 20172020 and the Compensation Committee’s determination of the correlation of their responsibilities with our overall corporate operating performance. Overall, the Compensation Committee determined that the base salary levels/increases were consistent with the Company’s overall compensation objectives and appropriate to retain our executives at a point in time at which the Company was achievinghad achieved strong results and the semiconductor equipment industry had a strong outlook.in fiscal 2019.

Fiscal 20172020 Cash Incentive Bonuses. OurOn March 19, 2020 the Compensation Committee approved target incentive cash compensation for our executive officers for 2020 under our Management Bonus Plan for fiscal 2017 awarded participants with cash incentives upon the achievement of specified levels of operating income. All of the(the “Management Bonus Plan”). The Company’s employees with a title of director and aboveexecutive officers were eligible to participate in the Management Bonus Plan. InPlan, which provided for the opportunity to earn quarterly and annual bonuses based on corporate and individual performance during the fiscal 2017, we paidyear. Bonuses under the Management Bonus Plan are based on each executive officer’s annual target cash incentive bonuses onopportunity (established as a percentage of each executive officer’s base salary, referred to as the basis“Target Bonus”).

For each executive officer, 85% of the cash bonus opportunity under the Management Bonus Plan was evaluated based on multiples (ranging from 0 to 2) of the Target Bonus based on performance of the Company against corporate goals and objectives as approved by the Compensation Committee for the applicable measurement period, 65% of which was based on quarterly achievementfinancial and operating performance and paid out quarterly, and 35% of target operating incomewhich was based on annual corporate goals and objectives and paid out annually. In addition, for fiscal 2017. These targetseach executive officer, an additional 15% of their cash bonus opportunity under the Management Bonus Plan was evaluated based on a multiple (ranging from 0 to 1) of the Target Bonus based on individual performance against annual individual goals and objectives as approved by the Compensation Committee and paid out annually. Under this Management Bonus Plan, bonuses based on corporate goals and objectives were limited to no more than twice the same as achievement levels set for fiscal 2016, as set forth inamount of 85% of the table below. While achievementapplicable executive officer’s Target Bonus, and bonuses based on individual goals and objectives were limited to no more than 15% of the same in fiscal 2017 as compared to fiscal 2016, the available bonus pool increased with increasing operating income, thus providing increased opportunities for improving results.

applicable executive officer’s Target Bonus. The Compensation Committee sets annual performance goalsmay increase or decrease bonuses calculated under the Management Bonus Plan at its discretion based on corporate or individual performance.

Corporate goals and objectives under the beginningManagement Bonus Plan may include goals and objectives relating to operational performance (e.g., quality and delivery performance), growth, implementation of strategic programs, financial results as compared to the Company’s operating plan or other benchmarks, and human resource initiatives. Individual goals and objectives were tailored to each executive officer’s position and were designed to award performance based on the individual’s contribution to the Company’s growth, financial performance, structural organization and achievement of strategic initiatives.

Target Bonus opportunities under the Management Bonus Plan are reviewed and approved on an annual basis for each named executive officer and established based on each named executive officer’s role and level of responsibility within the organization. For fiscal year. For 2017,2020, the target bonus percentages as a percentage of base salary for each of our named executive officers were consistent with those for fiscal 2019, as follows:

Under the Management Bonus Plan, an executive’s total cash incentive compensation cannot exceed 200% of the applicable executive’s annual target cash incentive compensation over the applicable bonus period, without the approval of the Compensation Committee.

In line with the bonus plan structure, which calls for a mid-year review of financial goals, in July 2020, the Compensation Committee believedreviewed a revised version of the Company’s annual operating plan, which incorporated a revised financial forecast for the second half of fiscal 2020 based on management’s assessment of the current state of the business and the Company’s industry, including the changes in the business outlook of the Company’s major customers.

For fiscal 2020, bonuses earned by our named executive officers under the Management Bonus Plan were as follows:

Quarterly achievement of corporate goals and objectives for our named executive officers for 2020 was determined based on a corporate scorecard approved by the Compensation Committee at the time of the adoption

of the Management Bonus Plan. These quarterly corporate goals and objectives were set based on key performance indicators for (i) quality and delivery performance as measured by customer scorecards, various internal quantitative quality and delivery metrics and qualitative assessments of customer satisfaction and (ii) financial performance, as measured by the Company’s actual revenue and free cash flow against the Company’s annual operating plan for 2020. Each of these goals was considered challenging but achievable at the time they were established.

Annual achievement of corporate goals and objectives for our named executive officers for 2020 was also determined based on a corporate scorecard approved by the Compensation Committee at the time of the adoption of the Management Bonus Plan. These annual corporate goals and objectives were based on key performance indicators for (i) growth, measured by the Company’s semiconductor revenue growth as compared to the overall market for wafer fab equipment growth and Services division revenue growth from integrated device manufacturers as compared to the overall market, (ii) the achievement of key strategic programs for the Company in 2020, including the Company’s ERP implementation, expense reduction, site optimization and product transition goals and (iii) the achievement of key human capital strategic goals, including global alignment of employee benefits, information systems, compensation policies and development plans. Each of these goals was considered challenging but achievable at the time they were established.

Annual achievement of individual goals and objectives for our named executive officers for 2020 was determined based on an individual scorecard for each named executive officer approved by the Compensation Committee at the time of the adoption of the Management Bonus Plan. For our Chief Executive Officer, individual performance was determined based on the achievement of organizational and operational streamlining initiatives, personal development goals and cash flow and inventory management targets. For our Chief Financial Officer, individual performance was determined based on the achievement of finance and systems integration initiatives, succession planning initiatives and initiatives relating to the integration of QGT’s financial reporting. Each of these goals was considered challenging but achievable at the time they were established.

The Compensation Committee determined that operating income was the mostabove goals and objectives for the 2020 Management Bonus Plan were appropriate metric upon which to basedrive successful execution of specific, near-term strategic objectives for the Company, enhance accountability, and continue to emphasize the Company’s financial performance during the fiscal year in the achievement of annual cash incentive bonuses, due towhile at the factsame time balancing near-term financial performance with strategic and operational objectives that it is highly correlated with both revenuewould support the Company’s long-term growth and profitabilitylong-term strategies.

After each quarter of fiscal 2020, the Compensation Committee reviewed actual corporate performance against the quarterly corporate scorecards, and effectively holdsin February 2021, the Compensation Committee reviewed actual corporate performance for fiscal 2020 against the annual corporate scorecards. Quarterly corporate scorecard achievement multiples ranged from 1.3 to 2.0 for quality and delivery performance, 1.3 to 1.8 for financial performance based on revenue and 0.4 to 2.0 for financial performance based on free cash flow. Annual corporate scorecard achievement was 1.9 for growth, 1.1 for achievement of strategic programs and 0.7 for achievement of human capital initiatives. The Compensation Committee approved payouts under the Management Bonus Plan for each quarter in fiscal 2020 and for the annual 2020 period consistent with the Company’s scorecard achievement.

In February 2021, the Compensation Committee also reviewed each of our named executive officers accountable for Company performance.officers’ actual individual performance against the annual individual scorecards. Following this review, the Compensation Committee determined to award our Chief Executive Officer an annual individual bonus equal to 14% (out of 15%) of his Target Bonus based on his achievement of goals relating to streamlining operations, succession planning, personal development, cash flow in excess of the Company’s annual operating plan and inventory control improvements. The Compensation Committee determined to award our Chief Financial Officer an additional annual individual bonus equal to 11.3% (out of 15%) of her Target Bonus based on her achievement of

goals relating to finance and systems integration initiatives and succession planning initiatives. The Compensation Committee also believeddetermined to award our other named executive officers additional annual individual bonuses ranging from 7% to 10.5% (out of 15%) based on their achievement of individual goals relating to operational performance, personal development, site financial performance, functional and systems integration, achievement of operating income, to be an appropriate metric based on its historical correlation withcustomer ramps, non-management personnel initiatives and cost initiatives.

Overall, actual bonuses for our common share price. Eachnamed executive officer has a target annual incentive bonus opportunity, expressedofficers as a percentage of his or her base salary with thefor 2020 were greater than for 2019 due primarily to our ability to earn above (upeffectively manage our operations through COVID-19. We were able to meet additional, drop-in demand as competitors were impacted by closures and significantly outgrow our base markets of wafer fab equipment (WFE) and wafer starts. The Compensation Committee believes that the Company’s cash incentive awards to the named executive officers for 2020 aligned pay with performance for 2020, notwithstanding a maximum equal to two times their target incentive compensation for such fiscal year) or below that targetchallenging economic environment in the Company’s industries, based on ourstrong performance against goals and initiatives that were designed in significant part to support the Company’s actual performance.

For fiscal 2017, for purposes of our Management Bonus Plan, operating income refers to operating income calculated in accordance with accounting principles generally accepted in the United States, but excluding thenon-cash amortization costslong-term growth and othernon-recurring expenses relating to our acquisitions. Operating Income is measured on a quarterly basis.long-term strategies, rather than merely near-term financial results.

over time while imposing continued service requirements, and requiring time-based vesting of the earned performance units). In April of 2017,2020, the Compensation Committee granted the following long-term equity awards to our named executive officers:

The number of equity awards the Compensation Committee granted to each executive officer in April 20172020 was determined based on a variety of factors, including each individual executive’s job performance and his or her level of job responsibility. The Compensation Committee also considered the use of long-term equity awards as a means to retain and incentivize executives. The size of each equity award granted to a named executive officer in 2019 was determined based on target cash value rather than a target number of units. Accordingly, the number of equity awards granted is alsowas influenced by our stock price at the time the awards arewere granted, as well as new hires and promotions.

The number and target value of RSUs granted to Mr. Scholhamer in fiscal 20172020 was set at a target value of $1.5approximately $2 million, an increase from the target value for the RSU granted to Mr. Scholhamer in fiscal 2019, as part of the Compensation Committee’s long-term goal of bettermore closely aligning our chief executive officer’sChief Executive Officer’s equity awards with market levels, and also to recognize Mr. Scholhamer’s strong performance and significant contributions to our organization. The dollar value of Ms. Savage’s RSUs granted in April 2017 was set at a value lower than fiscal 2016 due to the fact that Ms. Savage had received a significant promotional grant of RSUs in fiscal 2016 when she was promoted to our chief financial officer. The Compensation Committee also considered its long-term goal of setting grants at a level consistent with the market 50^th percentilemidrange provided to comparable officers by members of our peer group in determining grants for ournon-CEO named executive officers for fiscal 2017,2020 (and in the case of new hires, at levels competitive for such executives in the employment market), while at the same time considering the relative positions of each named executive officer within our global organization and past grant practices. The 20172020 equity awards granted in April 20172020 for our named executive officers showshown in the table above were all generally within targeted levels, as adjusted to maintain internal equity for named executive officers with similar levels of responsibility within our Company.

Following the Compensation Committee’s April 2017 meeting, the Compensation Committee subsequently determined to make the following additional awards of RSUs in fiscal 2017:

The additional grants to Ms. Savage and Mr. Lev shown in the table above where made in July and August of 2017, respectively, in connection with their additional responsibilities during our CEO’s leave of absence discussed above. The additional grant to Mr. Williams was made in July 2017 and was recommended to our Compensation Committee by our chief executive officer to recognize Mr. Williams outstanding performance in fiscal 2017 against his personal goals and key performance indicators.

The equity awards granted during fiscal 20172020 to our named executive officers are set forth in detail under “Grants of Plan-Based Awards” below. All time-based RSUs granted to our named executive officers in fiscal 2017,2020, and all PSUs earned based on fiscal 20172020 performance, vest over a period of 3 years from the grant date in equal annual installments.

Promotional and New Hire GrantsGrants. . The Compensation Committee’s policy has been to make promotional grants on solely a time-based vesting schedule to enhance retention.

Mix of Performance versus Time-based “Refresh” Grants.The mix of time-based and performance-based awards for grants made in April of 20172020 described above was consistent with prior years. In allocating equity awards between time-based and performance-based awards, the Compensation Committee considers each named executive officer’s level of responsibility, and the relationship between that named executive officer’s performance and our common share price. Consistent with prior years, theThe Compensation Committee determined that 55% and 50% of the annual “refresh” equity awards that were granted to our chief executive officerChief Executive Officer and our chief financial officerChief Financial Officer,

respectively, would consist of performance-based awards, because their roles focus more on overall corporate performance than our other named executive officers. For our other named executive officers, consistent with prior years, the Compensation Committee determined that 25% of the equity awards would consist of performance-based awards. Performance-based awards granted in fiscal 20172020 to our named executive officers are earned according to the following performance criteria (determined based on performance in fiscal 2017)2020). For fiscal 2017,2020, for purposes of our performance-based awards, operating income is calculated consistent with our Management Bonus Plan.

The Compensation Committee determined, based on our actual results for fiscal 2017,2020, that 100% of the performance-based awards granted to eligible named executive officers in fiscal 20172020 were earned.

Grant PracticesPractices.. We have implemented procedures to regularize our equity award grant process, by making new hire grants and annual executive grants on the same day each month. The Compensation Committee has not granted, nor does it intend in the future to grant, equity compensation awards to executives in anticipation of the release of material nonpublic information that is likely to result in changes to the price of our common stock, such as a significant positive or negative earnings announcement.announcements. Because our equity awards typically vest over multiple years, we believe recipients are motivated to see our stock price rise in the long-term rather than benefit from an immediate but short-term increase in the price of our stock following a grant.

2021 Equity Design. Throughout 2020 and into early 2021, the Compensation Committee worked with Semler Brossy to revise the design of the annual PSU awards. The new PSU awards were granted in April 2021 and will be disclosed in next year’s proxy statement.

In determining the new PSU design, the Compensation Committee sought to maintain strong alignment with the go-forward business strategy while also extending the performance horizon over a full three-year period (versus a one- year period), expanding the performance measurement to include a balance of top-line, bottom-line, and shareholder returns, and providing commensurate upside and downside opportunity where participants are eligible to earn between 0% up to 200% of their target opportunity based on performance against pre-determined goals (versus 0% to 100% under the previous design).

The design is primarily focused on relative revenue growth against a custom set of peers within the semiconductor industry with modifiers based on three-year average operating margin versus plan and three-year relative total shareholder return compared to the same set of peers used for the relative revenue growth assessment.

As part of the transition from a one-year to a three-year PSU program in 2021, the Compensation Committee awarded one-time Transition RSUs to help bridge the gap in vesting creating by extending the full performance period to three years. The Company will provide more details on these awards next year as they were awarded in April 2021 along with the normal annual grants.

Other Benefit Plans

Deferred CompensationCompensation.. We maintain anon-qualified deferred compensation plan, which allows eligible employees, including executive officers and directors, to voluntarily defer receipt of thea portion of his/her salary above a specified amount and all or a portion of a bonus payment until the date or dates elected by the participant, thereby allowing the participating employee to defer taxation on such amounts. This plan gives highly compensated employees the opportunity to defer more compensation than they would otherwise be permitted to defer under atax-qualified retirement plan, such as our 401(k) plan. We believe that deferred compensation is a competitive practice to enable us to attract and retain top talent. We do not make matching or other employer contributions to the deferred compensation plan because we believe the deferral opportunity is enough of a benefit on its own.

Executive PerquisitesPerquisites.. We offer limited perquisites to our executive officers. In addition to health care coverage that is generally available to our other employees, our executive officers are eligible for annual physical examinations more extensive than under the Company’s standard plans. In connection with Mr. Lev’s assignment to our Asian facilities at our request, we also agreed to make Mr. Lev whole for any income taxes for which he is responsible above that which he would be responsible for if he received a comparable salary as a resident the United States. No such tax equalization payments were made to Mr. Lev for fiscal 2017. See “—Summary Compensation Table” below for more information.

Other Benefits.We also offer a number of other benefits to the executive officers pursuant to benefit programs that provide for broad-based employee participation. For example, our retirement plan is atax-qualified 401(k) plan, which is a broad-based employee plan. Under the 401(k) plan, all participating employees (including executive officers) are eligible to receive limited matching contributions that are subject to vesting over time.

The main objectives of our benefits programs are to give our employees access to quality healthcare, financial protection from unforeseen events, assistance in achieving retirement financial goals, enhanced health and productivity and to provide support for global workforce mobility, in full compliance with applicable legal requirements. These generally available benefits typically do not specifically factor into decisions regarding an individual executive’s total compensation or equity award package.

Post-Termination Arrangements

Our post-termination arrangements with our named executive officers are described in this proxy statement below. We believe the severance benefits under these agreements or policies are reasonable in amount and provide protection to key executive officers who would be likely to receive similar benefits from our competitors. The Compensation Committee reviews the potential costs and triggering events of employment and severance agreements and policies before approving them and will continue to consider appropriate and reasonable measures to encourage retention.

Accounting and Tax Considerations

In designing our executive compensation programs, the Compensation Committee generally considers the accounting and tax effects as well as direct costs. We recognize a charge to earnings for accounting purposes when equity awards are granted. The Compensation Committee considers the impact to dilution and overhang when making decisions pertaining to equity instruments.

We do not require executive compensation to be tax deductible for the Company, but instead balance the cost and benefits of tax deductibility to comply with our executive compensation goals. This includes consideration of Section 162(m) of the Internal Revenue Code, which generally limits our ability to deduct compensation paid to each “covered employee” (as defined in the Internal Revenue Code) to the extent such individual’s compensation exceeds $1  million in any one year.

Compensation Committee Report

The Compensation Committee of the Board of Directors of Ultra Clean Holdings, Inc. has reviewed and discussed the Compensation Discussion and Analysis, which appears in this proxy statement, with the

management of Ultra Clean Holdings, Inc. Based on this review and discussion, the Compensation Committee recommended to the Board of Directors that the Compensation Discussion and Analysis be included in Ultra Clean Holdings, Inc.’s proxy statement.

Members of the Compensation Committee

Thomas T. Edman, Chair

David T. ibnAle Chair

Thomas T. Edman

Emily M. Liggett

Jacqueline A. Seto

Summary Compensation Table

The following table shows compensation information for the three most recently completed fiscal years for our principal executive officer, our principal financial officer and our other three most highly compensated executive officers as of December 29, 201725, 2020 (collectively, our “named executive officers”):