Document:

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                                                                     EXHIBIT 4.1

  NUMBER                                                           SHARES
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                            ULTRA CLEAN TECHNOLOGY (TM)

              INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

                                                             SEE REVERSE SIDE
                                                         FOR CERTAIN DEFINITIONS
                                                         -----------------------
                                                            CUSIP 90385V 10 7

THIS CERTIFIES THAT

IS THE OWNER OF

        FULLY PAID AND NON-ASSESSABLE COMMON SHARES, $0.001 PAR VALUE, OF

                           ULTRA CLEAN HOLDINGS, INC.

TRANSFERABLE ON THE BOOKS OF THE CORPORATION BY THE HOLDER HEREOF IN PERSON OR
BY ATTORNEY UPON SURRENDER OF THIS CERTIFICATE PROPERLY ENDORSED. THIS
CERTIFICATE IS NOT VALID UNLESS COUNTERSIGNED BY THE TRANSFER AGENT AND
REGISTRAR.

     IN WITNESS WHEREOF, THE SAID CORPORATION HAS CAUSED THIS CERTIFICATE TO BE
SIGNED BY FACSIMILE SIGNATURES OF ITS DULY AUTHORIZED OFFICERS.

     DATED:

        Secretary                                             President

The following abbreviations, when used in the inscription on the face of this
certificate, shall be construed as though they were written out in full
according to applicable laws and regulations:

TEN COM - as tenants in common

TEN END - as tenants by entireties

JT TEN - as joint tenants with right of survivorship and not as tenants in
common

UTMA - (Cust) Custodian (Minor) under Uniform Transfer to Minors Act (State)

Additional abbreviations may also be used though not in the above list.

For value received                  hereby sell, assign and transfer unto
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PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE
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PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS INCLUDING POSTAL ZIP CODE OF ASSIGNEE
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          Shares of the capital stock represented by the within Certificate, and
do hereby irrevocably constitute and appoint            Attorney to transfer the
said stock on books of the within-named Corporation with full power of
substitution in the premises.

Dated

NOTICE: THE SIGNATURE TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME AS
WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR WITHOUT ALTERATION
OR ENLARGEMENT OR ANY CHANGE WHATEVER.

SIGNATURE GUARANTEED
ALL GUARANTEES MUST BE MADE BY A FINANCIAL INSTITUTION (SUCH AS A BANK OR
BROKER) WHICH IS A PARTICIPANT IN THE SECURITIES TRANSFER AGENTS MEDALLION
PROGRAM ("STAMP"), THE NEW YORK STOCK EXCHANGE, INC. MEDALLION SIGNATURE PROGRAM
("MSP"), OR THE STOCK EXCHANGES MEDALLION PROGRAM ("SEMP") AND MUST NOT BE
DATED. GUARANTEES BY A NOTARY PUBLIC ARE NOT ACCEPTABLE.<PAGE>
                                                                    EXHIBIT 10.6

                                Option Agreement
                                    under the
                             Ultra Clean Corporation
                              Stock Incentive Plan

      Date of Grant:                                       _____________

      Name of Optionee:                                    _____________

      Number of Shares Subject to the Option:              _____________

      Exercise Price:                                      $____per share

         Ultra Clean Holdings, Inc., a Delaware corporation (the "COMPANY"),
hereby grants as of the date of grant set forth above (the "GRANT DATE") to the
above-named optionee ("OPTIONEE") an option (the "OPTION") to purchase from the
Company, for the price per share set forth above, the number of shares of common
stock of the Company ("SHARES") set forth above pursuant to the Ultra Clean
Holdings, Inc. Stock Incentive Plan (the "PLAN").

         Capitalized terms not otherwise defined herein shall have the same
meanings as in the Plan. The terms and conditions of the Option granted hereby,
to the extent not controlled by the terms and conditions contained in the Plan,
are as follows:

         1.       Exercise Price. The price at which each Share subject to this
Option may be purchased shall be the price set forth above.

         2.       Number of Shares, Exercise. The number of Shares for which the
Option may be exercised are set forth above. To the extent the Option has become
vested or exercisable in accordance with Section 3 hereof, the Option may be
exercised at any time through the date of expiration of the Option, as set forth
in Section 4 hereof.

         3.       Vesting. The Option shall vest and become exercisable on the
following schedule:(1)

                  (a)      The Option shall become vested and exercisable as to
         25% of the Shares constituting the Option on the first anniversary of
         the Grant Date, subject to Optionee's continued employment or service
         with the Company on such date.

                  (b)      Thereafter, the Option shall become vested and
         exercisable at a rate of 1/48 of the Shares constituting the Option per
         month, subject to Optionee's continued employment or service with the
         Company on each such date.

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         (1) This is the standard four-year vesting with one-year cliff. The
Board may decide on different vesting schedules for awards.

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         4.       Term of Option. The term of the Option commences on the Grant
Date and expires upon the earliest of the following:

                           (i)      immediately upon termination of Optionee's
                  employment or service with the Company and its Affiliates for
                  any reason, to the extent such Option is not yet vested or
                  does not become vested as a result of such termination;

                           (ii)     three months after termination of Optionee's
                  employment or service with the Company and its Affiliates by
                  Participant or by the Company or any of its Affiliates (other
                  than as a result of death or Disability or termination by the
                  Company for Cause);

                           (iii)    one year after Optionee's employment or
                  service with the Company and its Affiliates is terminated by
                  reason of Optionee's death or Disability;

                           (iv)     immediately upon termination of Optionee's
                  employment or service with the Company and its Affiliates by
                  the Company or any of its Affiliates for Cause;

                           (v)      the day before the tenth (10th) anniversary
                  of the Grant Date;

                           (vi)     in the event of a Change of Control, to the
                  extent not continued or assumed in accordance with Section
                  10(a) of the Plan; or

                           (vii)    in accordance with Section 10(b) of the
                  Plan.

         5.       Exercise.

                  (a)      Manner of Exercise. During the term of the Option set
         forth in Section 4 above, Optionee (or his representative, devisee or
         heir, as applicable) may exercise any portion of this Option which has
         become exercisable in accordance with the terms hereof as to all or any
         of the Shares then available for purchase by delivering to the Company
         written notice in the form specified by the Company. Payment shall be
         (i) in cash, by certified or bank cashier check payable to the order of
         the Company, free from all collection charges, (ii) in the discretion
         of the Committee, in Shares (provided such shares shall have been held
         by Optionee for at least six months unless the Committee determines in
         its sole discretion that such six-month holding period is not necessary
         to comply with any accounting, legal or regulatory requirement) having
         a Fair Market Value on the date of exercise equal to the full amount of
         the Exercise Price therefor, (iii) if approved by the Committee, in
         accordance with a cashless exercise program; or (iv) in such other form
         as may be permitted by the Committee. Only one stock certificate will
         be issued unless Optionee otherwise requests in writing. Shares
         purchased upon exercise of the Option will be issued in the name of
         Optionee or

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         Optionee's permitted transferee. Optionee shall not be entitled to any
         rights as a stockholder of the Company in respect of any Shares covered
         by this Option until such shares of Stock shall have been paid for in
         full and issued to Optionee.

                  (b)      Tax Withholding. By exercising the Option, Optionee
         agrees that, as a condition to any exercise of the Option, the Company
         may require Optionee to enter into an arrangement providing for the
         payment by Optionee to the Company of any tax withholding obligation of
         the Company arising by reason of (1) the exercise of the Option, (2)
         the lapse of any substantial risk of forfeiture to which the Shares are
         subject at the time of exercise, or (3) the disposition of Shares
         acquired upon such exercise. At any time Optionee exercises the Option,
         in whole or in part, or at any time as requested by the Company,
         Optionee hereby authorizes withholding from payroll and any other
         amounts payable to Optionee, any sums required to satisfy the federal,
         state, local and foreign tax withholding obligations of the Company, if
         any, which arise in connection with the Option.

                  (c)      Lock-up Period. By exercising the Option, Optionee
         agrees that the Company (or a representative of the underwriter(s))
         may, in connection with any underwritten registration of the offering
         of any securities of the Company under the Securities Act (including
         the Company's Initial Public Offering), require that Optionee not sell,
         dispose of, transfer, make any short sale of, grant any option for the
         purchase of, or enter into any hedging or similar transaction with the
         same economic effect as a sale, any Shares or other securities of the
         Company held by Optionee, for a period of time specified by the
         underwriter(s) (not to exceed one hundred eighty (180) days) following
         the effective date of the registration statement of the Company filed
         under the Securities Act. Optionee further agrees to execute and
         deliver such other agreements as may be reasonably requested by the
         Company and/or the underwriter(s) that are consistent with the
         foregoing or that are necessary to give further effect thereto. In
         order to enforce the foregoing covenant, the Company may impose
         stop-transfer instructions with respect to Optionee's Shares until the
         end of such period. The underwriters of the Company's stock are
         intended third party beneficiaries of this Subsection and shall have
         the right, power and authority to enforce the provisions hereof as
         though they were a party hereto.

         6.       Certificates. Certificates issued in respect of Shares
acquired upon exercise of the Option shall, unless the Committee otherwise
determines, be registered in the name of Optionee or Optionee's permitted
transferee. So long as Optionee is not bound by any transfer restrictions herein
or in the Plan, the Company shall deliver such certificates to Optionee or
Optionee's permitted transferee upon request. Such stock certificate shall carry
such appropriate legends, and such written instructions shall be given to the
Company transfer agent, as may be deemed necessary or advisable by counsel to
the Company in order to comply with the requirements of the Securities Act of
1933, any state securities laws or any other applicable laws.

         7.       Nontransferability of Option. This Option is personal to
Optionee and may be exercised only by Optionee or his or her representative in
the event of Optionee's

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Disability or death. Any Option shall not be transferable other than by will or
the laws of descent and distribution. Following transfer, any such Option shall
continue to be subject to the same terms and conditions as were applicable
immediately prior to transfer. The events of termination of employment or
service or death of Optionee set forth in the Plan shall continue to be applied
with respect to Optionee, following which the transferred Options shall be
exercisable by the transferee only to the extent and for the periods specified
in the Plan.

         8.       Employment Rights. This Option does not confer on Optionee any
right to continue in the employ or service of the Company or any Subsidiary or
interfere in any way with the right of the Company or any Subsidiary to
determine the terms of Optionee's employment or service.

         9.       Proprietary Information and Inventions Agreement. Optionee
shall, as a condition precedent to the exercise or settlement of an Award, have
executed and be in compliance with the Company's (or its subsidiary's) standard
form of confidentiality and non-disclosure agreement.

         10.      Terms of Plan, Interpretations. This Option and the terms and
conditions herein set forth are subject in all respects to the terms and
conditions of the Plan, which shall be controlling. All interpretations or
determinations of the Committee and/or the Board shall be binding and conclusive
upon Optionee and his legal representatives on any question arising hereunder.
Optionee acknowledges that he has received and reviewed a copy of the Plan.

         11.      Delegation. Optionee acknowledges that any powers, rights or
responsibilities of the Board and/or the Committee set forth herein may be
delegated to and exercised by any subcommittee thereof as permitted under the
Plan.

         12.      Notices. All notices hereunder to the party shall be delivered
or mailed to the following addresses:

         If to the Company:

                  Ultra Clean Holdings, Inc.
                  150 Independence Drive
                  Menlo Park, CA 94025
                  Attn:  Controller

         If to Optionee:

                  To the person and at the address specified on the signature
page.

         Such addresses for the service of notices may be changed at any time
provided notice of such change is furnished in advance to the other party.

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         13.      Entire Agreement. This Agreement contains the entire
understanding of the parties hereto in respect of the subject matter contained
herein. This Agreement and the Plan supersedes all prior agreements and
understandings between the parties hereto with respect to the subject matter
hereof.

         14.      Governing Law. This Option Agreement shall be governed by and
construed in accordance with the laws of the State of California, without
application of the conflict of laws principles thereof.

         15.      Counterparts. This Option Agreement may be signed in any
number of counterparts, each of which shall be an original, with the same effect
as if the signatures thereto and hereto were upon the same instrument.

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<PAGE>

         IN WITNESS WHEREOF, the undersigned have caused this Option Agreement
to be duly executed as of the date first above written.

                                         Ultra Clean Holdings, Inc.

                                         By:
                                            ___________________________________
                                            Name:
                                            Title:

                                         OPTIONEE:

                                         _______________________________________
                                         Name:
                                         Address:

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