<PAGE>

         FIRST AMENDMENT TO UNSECURED COMMITTED REVOLVER LOAN AGREEMENT

      This FIRST AMENDMENT TO UNSECURED COMMITTED REVOLVER LOAN AGREEMENT is
dated as of March 6, 2000 by and between:

      CITIZENS BANK OF MASSACHUSETTS (as successor in interest to State Street
Bank and Trust Company), with an address of 28 State Street, Boston,
Massachusetts 02109 (hereinafter, the "BANK"); and

      APPLIED SCIENCE AND TECHNOLOGY, INC., a Delaware corporation, with a
principal place of business at 35 Cabot Road, Woburn, Massachusetts 01801
(hereinafter, the "BORROWER").

                                   BACKGROUND

      WHEREAS, the Borrower and the Bank entered into a certain loan arrangement
(hereinafter, the "LOAN ARRANGEMENT") evidenced by, among other documents,
instruments, and agreements, a certain Unsecured Committed Revolver Loan
Agreement dated as of May 1, 1997 (hereinafter, the "REVOLVER AGREEMENT") and a
certain Unsecured Committed Revolver Promissory Note dated as of May 1, 1997
(hereinafter, the "NOTE") in the original principal amount of $8,000,000.00 made
payable by the Borrower to the order of the Bank; and

      WHEREAS, the Borrower has requested and the Bank has agreed to restructure
the terms and provisions of the Loan Arrangement, including, without limitation,
(i) an extension of the Expiration (as defined in the Revolver Agreement) from
May 31, 2000 through April 1, 2003; (ii) a change in the interest rate options
available to the Borrower from the Prime Rate (as defined in the Revolver
Agreement) and the Market Rate (as defined in the Revolver Agreement) to the
Domestic Rate (as defined hereunder) and the LIBOR Rate (as defined hereunder)
and (iii) a change in the applicable financial covenants, as set forth herein;

      Accordingly, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, it is hereby agreed by and among
the Bank and the Borrower as follows:

      1.    All references to the "Note" in the Revolver Agreement shall mean
            the Note, as amended by that certain First Amendment to Unsecured
            Committed Revolver Promissory Note dated March 6, 2000.

      2.    The term "Loans" as set forth in Section 1.0 of Article I of the
            Revolver Agreement is hereby deleted in its entirety and replaced
            with the following:
<PAGE>

            " "Loans" shall mean Domestic Rate Loans, LIBOR Rate Loans and
            Standby Letters of Credit issued by the Bank from time to time
            hereunder".


      3.    The terms "Domestic Rate Loan" and "LIBOR Rate Loan" shall have the
            meanings ascribed to such terms within Exhibit A, attached to and
            made a part hereof. All other terms so defined within Exhibit A are
            hereby incorporated by reference.

      4.    The terms "Market Rate", "Market Rate Loan", "Prime Rate", and
            "Prime Rate Loan" as set forth in the Revolver Agreement are hereby
            deleted in their entirety.

      5.    The last sentence of Section 2.1 of Article II of the Revolver
            Agreement is hereby deleted in its entirety and replaced with the
            following:

            " The principal amount of the Revolver shall be payable upon the
            earlier of either (a) the expiration of this Agreement on April 1,
            2003 (the "Expiration") or (b) upon the occurrence of an Event of
            Default (subject to and as provided herein)."

      6.    Section 2.2 and 2.5 of Article II of the Revolver Agreement and
            Subsections (1), and (2) of Section 2.3 of Article II of the
            Revolver Agreement are hereby deleted in their entirety. All terms
            and conditions relating to the advances of Loans under the Revolver
            Agreement, the applicable rate of interest accruing on outstanding
            loans, and the repayment of such Loans shall be governed by the
            terms and provisions set forth within Exhibit A, attached hereto and
            made a part hereof.

      7.    Subsection (4) of Section 2.3 of Article II of the Revolver
            Agreement is hereby deleted in its entirety and replaced with the
            following:

            "Default Rate. Any principal amount not paid immediately upon
            acceleration by reason of an Event of Default shall bear interest
            thereafter, until paid, at a rate equal to the aggregate of the
            Domestic Rate plus four (4%) percent per annum (the "Default
            Rate")."

      8.    Section 3.0 of Article III of the Revolver Agreement is hereby
            deleted in its entirety and replaced with the following:



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<PAGE>

            "The proceeds of the Loans hereunder shall be used only for the
            purpose of supporting acquisition financing, letters of credit, and
            working capital requirements."

      9.    The date of the consolidated balance sheet set forth in Section 5.4
            of Article V of the Revolver Agreement shall be changed from "June
            29, 1996" to "June 26, 1999" and the date of the Borrower's Form
            10-K shall be changed from "1996" to "1999".

      10.   The date of the Borrower's Form 10-K set forth in Article V, Section
            5.7 of the Revolver shall be changed from "1996" to "1999".

      11.   All references to the "Acquisition Transaction" shall hereby be
            deleted in the entirety.

      12.   Section 8.0 of Article VIII of the Revolver is hereby deleted in its
            entirety and replaced with the following:

            "So long as the Note shall remain unpaid or the Bank shall have any
            commitment under this Agreement:

            1.    The Borrower will maintain Minimum Working Capital of not less
                  than $18,000,000.00 at the end of each of Borrower's fiscal
                  quarter.

            2.    The Borrower will maintain at all times a Maximum Debt to
                  Tangible Net Worth ratio of no more than: 1.50:1 from and
                  after December 31, 1999.

            3.    As of March 31, 1999, the Borrower will maintain a Tangible
                  Net Worth of not less than $30,000,000.00. Thereafter, the
                  Borrower's Tangible Net Worth will increase (as of the end of
                  each of the Borrower's quarters) by a minimum of an aggregate
                  of 40% of the prior quarter's Net Income.

            4.    The Borrower will maintain Minimum Debt Service Coverage
                  defined as the ratio of aggregate Net Income of the Borrower
                  plus aggregate depreciation, plus aggregate amortization, less
                  aggregate Capital Expenditures not financed on a



                                     - 3 -
<PAGE>

                  long-term basis to Current Maturities of Long Term Debt of the
                  Borrower of 1.75:1. This covenant shall be tested on a rolling
                  quarterly basis for a four fiscal quarter period.


            5.    The Borrower will not suffer a negative Net Income for two
                  fiscal quarters during any fiscal year.

                  All of the foregoing covenants shall be tested as of the last
                  day o f each of the Borrower's fiscal quarters commencing with
                  the Borrower's fiscal quarter first ending on March __, 2000.

                  Capitalized terms otherwise not defined herein shall be
            defined in accordance with GAAP."

      13.   Subsection (5) of Section 9.0 of Article IX of the Revolver
            Agreement is hereby deleted in its entirety and replaced with the
            following:

            "There exists any Event of Default as defined under that certain
            loan arrangement by and between ASTeX Realty Corp. and the Bank
            evidenced by, among other documents, instruments and agreements,
            that certain Loan Agreement dated as of March 6, 2000, and that
            certain Note dated as of March 6, 2000 in the original principal
            amount of $10,000,000.00."

      14.   Section 11.1 of Article XI of the Revolver Agreement is hereby
            deleted in its entirety and replaced with the following:

            "Each notice, demand, election or request provided for or permitted
            to be given pursuant to this Agreement or any other Loan Document
            (hereinafter in this Section referred to as "Notice") must be in
            writing and shall be deemed to have been properly given or served by
            personal delivery or by sending same by overnight courier or by
            depositing same in the United States Mail, postpaid and registered
            or certified, return receipt requested, and addressed as follows:

            If to the Bank;

                  Citizens Bank of Massachusetts
                  28 State Street
                  Boston, Massachusetts 02109
                  Attn: Ms. Suzanne Dwyer, Vice President



                                     - 4 -
<PAGE>

            With a copy to:

                  Riemer & Braunstein LLP
                  Three Center Plaza
                  Boston, Massachusetts 02108
                  Attn: Jonathan D. Yellin, Esquire

            If to the Borrower:

                  Applied Science and Technology, Inc.
                  35 Cabot Road
                  Woburn, Massachusetts 01801
                  Attn: William S. Hurley, Senior Vice President and
                        Chief Financial Officer

            With a copy to:

                  Mintz Levin Cohn Ferris Glovsky & Popeo, PC
                  1 Financial Center
                  Boston, Massachusetts 02111
                  Attn: Stephen T. Langer, Esquire

            Each Notice shall be effective upon being personally delivered or
            upon being sent by overnight courier or upon being deposited in the
            United States Mail as aforesaid. The time period in which a response
            to such Notice must be given or any action taken with respect
            thereto (if any), however, shall commence to run from the date of
            receipt if personally delivered or sent by overnight courier, or if
            so deposited in the United States Mail, the earlier of three (3)
            Business Days following such deposit or the date of receipt as
            disclosed on the return receipt. Rejection or other refusal to
            accept or the inability to deliver because of changed address for
            which no Notice was given shall be deemed to be receipt of the
            Notice sent. By giving at least thirty (30) days' prior Notice
            thereof, the Borrower or the Bank shall have the right from time to
            time and at any time during the term of this Agreement to change
            their respective addresses and each shall have the right to specify
            as its address any other address within the United States of
            America."

      15.   The Borrower hereby ratifies, confirms, and reaffirms all of the
            terms and conditions of the Revolver Agreement, and all of the other
            documents, instruments, and agreements evidencing the Loan
            Arrangement including, without limitation, the Note. In addition,
            the Borrower acknowledges and agrees that the Bank is not agreeing
            by this First Amendment to Unsecured Committed Revolver Loan
            Agreement to amend, modify, or alter any of the terms and conditions
            of the Loan Arrangement except to the extent provided herein.

      16.   Any determination that any provision of this First Amendment to
            Unsecured Committed Revolver Loan Agreement or any application
            hereof is invalid, illegal or unenforceable in any respect and in
            any instance



                                     - 5 -
<PAGE>

            shall not effect the validity, legality, or enforceability of such
            provision in any other instance, or the validity, legality or
            enforceability of any other provisions of this First Amendment to
            Unsecured Committed Revolver Loan Agreement.

      17.   The Borrower shall pay on demand all costs and expenses of the Bank,
            including, without limitation, reasonable attorneys' fees in
            connection with the preparation, negotiation, execution and delivery
            of this First Amendment to Unsecured Committed Revolver Loan
            Agreement.

      18.   The Borrower warrants and represents that the Borrower has consulted
            with independent legal counsel of the Borrower's selection in
            connection with this First Amendment to Unsecured Committed Revolver
            Loan Agreement and is not relying on any representations or
            warranties of the Bank or its counsel in entering into this First
            Amendment to Unsecured Committed Revolver Loan Agreement.

      19.   The Borrower acknowledges, confirms and agrees that it has no
            offsets, defenses, claims or counterclaims against the Bank with
            respect to any of the Borrower's liabilities and obligations to the
            Bank under the Loan Arrangement, and to the extent that the Borrower
            has any such claims under the Loan Arrangement, the Borrower
            affirmatively WAIVES and RENOUNCES such claims as of the date
            hereof.


                                     - 6 -
<PAGE>

      IN WITNESS WHEREOF, this First Amendment to Unsecured Committed Revolver
Loan Agreement has been executed as a sealed instrument as of the date first set
forth above.



WITNESS:                                  BORROWER

/s/ C. L. Glynn                           APPLIED SCIENCE AND TECHNOLOGY, INC.
------------------
                                          By:  /s/ William S. Hurley
                                              ---------------------------------
                                          Name: William S. Hurley
                                          Title: Senior Vice President and
                                                 Chief Financial Officer



Acknowledged and Agreed to:
CITIZENS BANK OF MASSACHUSETTS

By:    /s/ Suzanne L. Dwyer
    ---------------------------------
Name:  Suzanne L. Dwyer
      -------------------------------
Title: Vice President
       ------------------------------



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