<PAGE>

                                                                    EXHIBIT 10.5

                         CONSENT AND AMENDMENT AGREEMENT

                This Consent and Amendment Agreement (this "Agreement"), dated
as of February 7, 2003, is by and among ENTEGRIS, INC., a Minnesota corporation
(the "Borrower"), the Banks (defined in the Credit Agreement, defined below) and
WELLS FARGO BANK, NATIONAL ASSOCIATION, a national banking association, in its
separate capacity as administrative agent for the Banks (in such capacity, the
"Agent").

                The Borrower, the Banks and the Agent are parties to a Credit
Agreement dated as of November 30, 1999 (as amended, supplemented or modified to
date, the "Credit Agreement").

                The Borrower has requested the consent of the Agent and the
Banks to the Borrower's acquisition (the "Acquisition") of certain assets from
Asyst Technologies, Inc., a California corporation (the "Seller"), pursuant to
the terms of an Asset Purchase Agreement dated as of February 11, 2003 among
Entegris Cayman Ltd., a Cayman Island corporation and wholly-owned subsidiary of
the Borrower and the Borrower (collectively, the Borrower and such subsidiary
being the "Buyer") and the Seller (the "Purchase Agreement").

                The Agent and the Banks have agreed to provide such consent on
the terms and subject to the conditions of this Agreement.

                Accordingly, in consideration of the mutual covenants herein
contained, the parties hereto agree as follows:

                1.      Definitions. All capitalized terms used in this
Agreement not otherwise specifically defined herein shall have the meanings
given to such terms in the Credit Agreement.

                2.      Consent. Subject to the conditions set forth in this
Agreement, the Agent and the Banks consent to the Acquisition for all purposes
of the Credit Agreement and waive any Default or Event of Default which would
result therefrom absent such consent. The consent described above is limited to
its express terms. Except as expressly set forth above, the consent given in
this Section 2 shall not operate as a consent to or waiver of any Default, Event
of Default, breach of or other departure from any provision of the Credit
Agreement or any other Loan Document, whether existing or future and whether
known or unknown.

                3.      Amendment. The Credit Agreement is hereby amended to add
Section 5.11 as set forth below:

                "Section 5.11 Minimum Cash and Cash Equivalents. The Borrower
        will at all times maintain cash and cash equivalents of not less than
        $75,000,000, such cash and cash equivalents to at all times be owned
        solely by the Borrower."

                                        1

<PAGE>

                4.      Conditions Precedent. This Agreement shall become
effective when the Agent shall have received the following, each in form and
content acceptable to the Agent in its sole discretion:

                (a)     this Agreement, duly executed on behalf of the Borrower,
        the Banks and the Agent;

                (b)     Copies of the Articles of Incorporation and Bylaws of
        the Borrower certified by the Secretary or Assistant Secretary of the
        Borrower as being true and correct copies thereof;

                (c)     A certified copy of the resolutions of the board of
        directors of the Borrower evidencing approval of this Agreement and all
        matters contemplated hereby;

                (d)     A signed copy of a certificate of the Secretary or an
        Assistant Secretary of the Borrower, which shall certify the names of
        the officers of the Borrower authorized to sign this Agreement and the
        documents to be executed by the Borrower in connection therewith,
        together with the true signatures of such officers.

                (e)     A Certificate of good standing of the Borrower, dated
        not more than thirty (30) days prior to the date hereof;

                (f)     the Purchase Agreement, complete with all schedules and
        exhibits thereto, duly executed on behalf of all parties thereto;

                (g)     the Acquisition is completed in accordance with the
        terms of the Purchase Agreement, for an amount not to exceed the
        Purchase Price (as defined in the Purchase Agreement);

                (h)     the Borrower has executed and returned a commitment
        letter dated as of even date herewith relating to certain additional
        financing contemplated among the Agent, the Banks and the Borrower;

                5.      Representations and Warranties of the Borrower. The
Borrower hereby represents and warrants to the Agent and the Banks as follows:

                (a)     The Borrower has all requisite power and authority to
        execute and deliver this Agreement and to perform all of its obligations
        under this Agreement and the Credit Agreement as amended hereby and this
        Agreement has been duly executed and delivered by the Borrower and this
        Agreement and the Credit Agreement as amended hereby constitute the
        legal, valid and binding obligations of the Borrower, enforceable in
        accordance with their terms.

                (b)     The execution, delivery and performance by the Borrower
        of this Agreement and its performance of the Credit Agreement as amended
        hereby have

                                        2

<PAGE>

        been duly authorized by all necessary corporate action and do not (i)
        require any authorization, consent or approval by any governmental
        department, commission, board, bureau, agency or instrumentality,
        domestic or foreign, (ii) violate any provision of any law, rule or
        regulation or of any order, writ, injunction or decree presently in
        effect, having applicability to the Borrower, or the Articles of
        Incorporation or Bylaws of the Borrower, or (iii) result in a breach of
        or constitute a default under any indenture or loan or credit agreement
        or any other agreement, lease or instrument to which the Borrower is a
        party or by which it or its properties may be bound or affected.

                (c)     All of the representations and warranties contained in
        Article IV of the Credit Agreement are correct on and as of the date
        hereof as though made on and as of such date, except to the extent that
        such representations and warranties relate solely to an earlier date.

                6.      Counterparts. This Agreement may be executed in any
number of counterparts, each of which shall be deemed to be an original and all
of which counterparts taken together shall constitute but one and the same
instrument.

                7.      Costs and Expenses. All out-of-pocket costs and expenses
of the Agent (including fees of outside counsel to the Agent) incurred in
connection with this Agreement and the matters contemplated hereby will be
governed by Section 9.4 of the Credit Agreement and shall be deemed incurred in
connection with the negotiation of amendments to the Loan Documents.

                8.      References; Effect. All references in the Credit
Agreement to "this Agreement" shall be deemed to refer to the Credit Agreement
as amended by this Agreement; and any and all references in any of the other
Loan Documents to the "Credit Agreement" shall be deemed to refer to the Credit
Agreement as amended by this Agreement. Except as otherwise amended by this
Agreement, all of the terms and conditions of the Credit Agreement and the other
Loan Documents shall remain in full force and effect in accordance with their
terms.

                9.      Governing Law. This Agreement shall be governed by and
construed in accordance with the substantive laws of the State of Minnesota.

                            [Signature Page Follows]

                                        3

<PAGE>

                IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be executed by their respective officers thereunto duly authorized,
as of the date first above written.

                                          ENTEGRIS, INC.


                                          By           /s/  John Villas
                                             -----------------------------------
                                               Its    Chief Financial Officer
                                                   -----------------------------


                                          By       /s/  James E. Dauwalter
                                             -----------------------------------
                                               Its    Chief Executive Officer
                                                   -----------------------------


                                          WELLS FARGO BANK, NATIONAL
                                          ASSOCIATION, as a Bank and as Agent


                                          By      /s/  Richard G. Trembley
                                             -----------------------------------
                                               Its        Vice President
                                                   -----------------------------


                                          HARRIS TRUST AND SAVINGS BANK,
                                          as a Bank


                                          By       /s/ Michael M. Fordney
                                             -----------------------------------
                                               Its         Vice President
                                                   -----------------------------

               [Signature Page to Consent and Amendment Agreement]

                                        4