<PAGE>

Exhibit 10h

                           ------------------------

                            KEY EMPLOYEE AGREEMENT

                           -------------------------

                                                        As of February 1, 2000


To:  Jack J. Schuss
     8 Cedar Street
     Newton, MA 02459

     The undersigned, Applied Science and Technology, Inc., a Delaware
corporation, as well as its successors and assigns (hereinafter collectively
referred to as the "Company"), hereby agree with you as follows:

     l.   Position and Responsibilities.
          -----------------------------

          1.1  You shall serve as Vice President, Engineering (or in such other
capacity as shall be designated by the President or Board of Directors and
reasonably acceptable to you). You will, to the best of your ability, devote
your full time and best efforts to the performance of your duties hereunder and
the business and affairs of the Company and perform such duties as may be
assigned to you by or on authority of the Company's President from time to time
and the duties customarily associated with such capacity from time to time and
at such place or places as the Company shall designate as appropriate and
necessary in connection with such employment.

          1.2  You will duly, punctually and faithfully perform and observe any
and all rules and regulations which the Company may now or shall hereafter
establish governing the conduct of its business.

          1.3  You will report directly to the Company's President and will be
based out of the Company's Woburn office.

     2.   Term of Employment.
          ------------------

          2.1  The initial term of this Agreement shall be for the period set
forth on Exhibit A annexed hereto commencing with the date hereof.  Thereafter,
         ---------
this Agreement shall be automatically renewed for successive periods of one
year, unless you or the Company shall give the other party not less than thirty
(30) days written notice of non-renewal.  Your employment with the Company may
be terminated as provided in Section 2.2.

                                      A-1
<PAGE>

          2.2  The Company shall have the right, upon written notice to you, to
     terminate your employment:
               (a)  immediately at any time for "Cause" (as defined herein
     subject to your right of cure and right to dispute as provided in Section
     2.3 herein); or

               (b)  at any time, without "Cause," provided that the Company
     shall be obligated to pay to you the Severance Benefits set forth in
     Section 6, Exhibit A, plus any sums then due to you, including those
                ---------
     expenses as are provided for in Section 4 of Exhibit A, less (i) applicable
                                                  ---------
     taxes and other required withholdings, and (ii) any amounts you may owe to
     the Company.  Payments under this Section 2.2 (b) shall not be due or
     payable if you are terminated at any time for "Cause" or if you voluntarily
     resign from your employment.

          2.3  For purposes of Section 2.2, the term "Cause" shall mean (a)
gross negligence or willful misconduct in the performance of assigned duties;
(b) material and repetitive refusal to perform or discharge the duties or
responsibilities assigned by the President of the Company provided the same are
not illegal, unethical or inconsistent with the position of Vice President,
Engineering, of a corporation and the failure to correct such refusal and
perform such duties or responsibilities within a reasonable period of time (but
in any event no less than seven (7) calendar days after written notice of such
failure); (c) conviction of a felony or misdemeanor involving moral turpitude;
(d) willful or prolonged absence from work not excused by a bona fide medical
disability as reasonably determined by a qualified physician mutually acceptable
to both you and the Company or other good cause as reasonably determined by the
Board of Directors; and (e) falseness of any warranty or representation by you
herein or the breach of your material obligations under this Agreement to the
material detriment of the Company.

          2.4  In the event of the Involuntary Termination (as hereinafter
defined) of your employment with the Company at any time, the Company hereby
agrees to provide you with Severance Benefits as defined in Section 6 of Exhibit
                                                                         -------
A hereto.  In this regard, the phrase "Involuntary Termination" shall mean (a)
-
any termination of your employment by the Company other than for "cause," as
defined in Section 2.3 or (b) any notice by the Company not to renew this
Agreement pursuant to Section 2.1.

          2.5  You shall have the right to terminate this Agreement upon not
less than thirty (30) days prior written notice to the Company.

     3.   Compensation.  You shall receive the compensation and benefits set
          ------------
forth on Exhibit A ("Compensation") for all services to be rendered by you
         ---------
hereunder and for your transfer of property rights pursuant to an agreement
relating to proprietary information and inventions of even date herewith
attached hereto as Exhibit C between you and the Company (the "Proprietary
Information and Inventions Agreement").

                                      A-2
<PAGE>

     4.   Other Activities During Employment.
          ----------------------------------

          4.1  Except for any outside employments and directorships currently
held by you as listed on Exhibit B, and/or except with the prior written consent
                         ---------
of the Company's Senior Vice President and Chief Operating Officer, you will not
during the term of this Agreement undertake or engage in any other employment,
occupation or business enterprise other than one in which you are an inactive
investor.

          4.2  You hereby agree that, except as disclosed on Exhibit B hereto,
                                                             ---------
during your employment hereunder, you will not, directly or indirectly, engage
(a) individually, (b) as an officer, (c) as a director, (d) as an employee, (e)
as a consultant, (f) as an advisor, (g) as an agent (whether a salesperson or
otherwise), (h) as a broker, or (i) as a partner, coventurer, stockholder or
other proprietor owning directly or indirectly more than two percent (2%)
interest, in any firm, corporation, partnership, trust, association, or other
organization which is engaged in the research, development, production,
manufacture or marketing of equipment or processes in direct competition with
the Company or any other line of business engaged in or under demonstrable
development by the Company (such firm, corporation, partnership, trust,
association, or other organization being hereinafter referred to as a
"Prohibited Enterprise").  Except as may be shown on Exhibit B, you hereby
                                                     ---------
represent that you are not engaged in any of the foregoing capacities (a)
through (i) in any Prohibited Enterprise.

     5.   Former Employers.
          ----------------

          5.1  You represent and warrant that your employment by the Company
will not conflict with and will not be constrained by any prior or current
employment, consulting agreement or relationship whether oral or written.  You
represent and warrant that you do not possess confidential information arising
out of any such employment, consulting agreement or relationship which, in your
best judgment, would be utilized in connection with your employment by the
Company in the absence of Section 5.2.

          5.2  If, in spite of the second sentence of Section 5.1, you should
find that confidential information belonging to any other person or entity might
be usable in connection with the Company's business, you will not intentionally
disclose to the Company or use on behalf of the Company any confidential
information belonging to any of your former employers; but during your
employment by the Company you will use in the performance of your duties all
information which is generally known and used by persons with training and
experience comparable to your own all information which is common knowledge in
the industry or otherwise legally in the public domain.

     6.   Proprietary Information and Inventions.  You agree to execute, deliver
          --------------------------------------
and be bound by the provisions of the Proprietary Information and Inventions
Agreement.

                                      A-3
<PAGE>

     7.   Remedies.  Your obligations under the Proprietary Information and
          --------
Inventions Agreement and the provisions of Sections 4, 6, and 8 of this
Agreement (as modified by Section 9, if applicable) shall survive the expiration
or termination of your employment (whether through your resignation or
otherwise) with the Company.  You acknowledge that a remedy at law for any
breach or threatened breach by you of the provisions of the Proprietary
Information and Inventions Agreement would be inadequate and you therefore agree
that the Company shall be entitled to such injunctive or other equitable relief
in case of any such breach or threatened breach.

     8.   Assignment.  This Agreement and the rights and obligations of the
          ----------
parties hereto shall bind and inure to the benefit of any successor or
successors of the Company by reorganization, merger or consolidation and any
assignee of all or substantially all of its business and properties, but, except
as to any such successor or assignee of the Company, neither this Agreement nor
any rights or benefits hereunder may be assigned by the Company or by you,
except by operation of law.  The Company's obligations and those of any
successors or assignees of the Company under this Agreement, including but not
limited to the severance provisions and other compensation and benefits due to
you pursuant to Exhibit A hereto, will be a condition of and are to remain those
                ---------
of any successor or assignee.

     9.   Interpretation.  IT IS THE INTENT OF THE PARTIES THAT in case any one
          --------------
or more of the provisions contained in this Agreement shall, for any reason, be
held to be invalid, illegal or unenforceable in any respect, such invalidity,
illegality or unenforceability shall not affect the other provisions of this
Agreement, and this Agreement shall be construed as if such invalid, illegal or
unenforceable provision had never been contained herein.  MOREOVER, IT IS THE
INTENT OF THE PARTIES THAT in case any one or more of the provisions contained
in this Agreement shall for any reason be held to be excessively broad as to
duration, geographical scope, activity or subject, such provision shall be
construed by limiting and reducing it as determined by a court of competent
jurisdiction, so as to be enforceable to the extent compatible with applicable
law.

     10.  Notices.  Any notice which the Company is required to or may desire to
          -------
give you shall be given by personal delivery or registered or certified mail,
return receipt requested, addressed to you at your address of record with the
Company, or at such other place as you may from time to time designate in
writing.  Any notice which you are required or may desire to give to the Company
hereunder shall be given by personal delivery or by registered or certified
mail, return receipt requested, addressed to the Company at its principal
office, or at such other office as the Company may from time to time designate
in writing.  The date of personal delivery or the date of mailing any notice
under this Section 10 shall be deemed to be the date of delivery thereof.

     11.  Waivers.  If either party should waive any breach of any provision of
          -------
this Agreement, such party shall not thereby be deemed to have waived any
preceding or succeeding breach of the same or any other provision of this
Agreement.

                                      A-4
<PAGE>

     12.  Complete Agreement; Amendments.  The foregoing including Exhibits A,
          ------------------------------
B, C, D and E hereto, is the entire agreement of the parties with respect to the
subject matter hereof, superseding any previous oral or written communications,
representations, understandings, or agreements with the Company or any officer
or representative thereof.  Any amendment to this Agreement or waiver by the
Company of any right hereunder shall be effective only if evidenced by a written
instrument executed by the parties hereto, upon authorization of the Company's
Board of Directors.

     13.  Headings.  The headings of the Sections hereof are inserted for
          --------
convenience only and shall not be deemed to constitute a part hereof nor to
affect the meaning of this Agreement.

     14.  Counterparts.  This Agreement may be signed in two counterparts, each
          ------------
of which shall be deemed an original and both of which shall together constitute
one agreement.

     15.  Governing Law; Venue.  This Agreement shall be governed by and
          --------------------
construed under Massachusetts law.

     16.  Advice of Separate Counsel.  You acknowledge that you have been
          --------------------------
advised to review this Agreement with your own legal counsel and other advisors
of your choosing and that prior to entering into this Agreement, you have had
the opportunity to review this Agreement with your attorney and other advisors
and have not asked (or relied upon) Mintz, Levin, Cohn., Ferris, Glovsky and
Pope, P.C. to represent you in this matter.

     If you are in agreement with the foregoing, please sign your name below and
also at the bottom of the Proprietary Information and Inventions Agreement and
Stock Option Grant Letter, whereupon this Agreement shall become binding in
accordance with its terms.  Please then return this Agreement to the Company.
(You may retain for your records the accompanying counterpart of this Agreement
enclosed herewith).


ACCEPTED AND AGREED:                        APPLIED SCIENCE AND
                                            TECHNOLOGY, INC.


/s/ Jack J. Schuss                          By: /s/ Dr. Richard S. Post
-----------------------------                   --------------------------------
Jack J. Schuss                                  Dr. Richard S. Post, President

                                      A-5
<PAGE>

                                                                       EXHIBIT A
                                                                       ---------

                  EMPLOYMENT TERM, COMPENSATION AND BENEFITS
                               OF JACK J. SCHUSS

     l.   Term.  The term of the Agreement to which this Exhibit A is attached
          ----
and made a part shall be for a period from the date of this Agreement through
February 1, 2001.

     2.   Compensation.
          ------------

          (a)  Base Salary.  Your base salary ("Base Salary") shall be $6,730.76
               -----------
payable on a bi-weekly basis ($175,000 on an annualized basis) through September
30, 2000, payable in accordance with the Company's payroll policies.  Commencing
October 1, 2000 your base salary shall be established by the Board of Director's
Compensation Committee.

          (b)  Bonuses.  The Company shall establish appropriate incentive
               -------
compensation plans ("Bonuses") for you for each fiscal year that you are
employed hereunder, commencing with Fiscal 2000  which commences on June 27,
1999, under which you shall be entitled to a prorated bonus of up to 30% of your
then current Base Salary based on the Company attaining certain financial and
other results and also based upon individual goals to be established for you.
Such Bonuses shall be properly approved by the Board of Directors or the
Compensation Committee of the Board of Directors.

     3.   Vacation, Insurance and Benefits; Expenses.  You shall be entitled to
          ------------------------------------------
all legal holidays recognized by the Company, and 15 days paid vacation per
annum.  Any unused vacation may be accrued or used in accordance with Company
policy. You shall be eligible for participation in any health, dental,  and
other group insurance plans which may be established and maintained by the
Company for all full-time employees or which the Company is required to maintain
by law.  You shall also be entitled to participate in any employee benefit
programs which the Company's Board of Directors may establish for Company
employees generally, including, but not limited to, bonuses and stock purchase
or option plans.  You will be eligible to participate in the Company's 401(k)
Plan. The Company shall reimburse you for all usual and ordinary business
expenses incurred by you in the scope of your employment hereunder in accordance
with the Company's expense reimbursement policy.

     4.   Initial Stock Options.  You shall be entitled to receive stock options
          ---------------------
to purchase up to an aggregate of 30,000 shares of common stock of the Company.
Such options shall be priced on the closing price of the Company's Common Stock
as reported by NASDAQ on the date you commence employment with the Company and
shall vest as follows: the stock options have a four year vesting period, with
20% vesting after six months, 20% vesting after one year, 20% at the end of two
years, 20% at the end of three years, and full vesting at the end of four years
in four equal annual installments on the anniversary date of such grant.  A copy
of the

                                      A-6
<PAGE>

forms of option grant letter is attached hereto as Exhibits D and E.
                                                   ----------------
Notwithstanding the foregoing, in the event of a Change of Control (as defined
in Section 7 herein), an additional 20% of such option shall vest upon the
Change of Control (but in any event not to exceed 100% of the original option
grant).

     5.   Subsequent Stock Options.  You shall be entitled to additional stock
          ------------------------
options as determined by the compensation committee of ASTeX's Board of
Director's in its sole discretion.  An additional 10,000 options may be granted
based on a performance review on or about October 1, 2000.  An additional 10,000
options may be granted based on a second review on or about October 1, 2001.

     6.   Severance Benefits.
          ------------------
          (a)  When provided for in this Agreement, you shall be entitled to
"Severance Benefits."  When used in this Agreement, the term "Severance
Benefits" shall mean a total amount equal to one hundred percent (100%) of your
then current Base Salary if you are involuntarily terminated for any reason
other than for cause, for a period not to exceed six (6) months or up until when
you start another full time position if it is prior to six months from your
termination date. The Severance Benefits shall be paid via check to you in six
(6) equal monthly installments commencing within ten (10) days after the date of
your termination of employment with the Company.

          (b)  In addition, the term "Severance Benefits" shall include the
continuation for you and your family, during the Severance Period, as defined
below, of all of the other benefits which are provided or available to you on
the last day of your actual service with the Company.  For purposes of this
Agreement, the term "Severance Period" means the period of six (6) months
beginning on the Date of Termination.

          (c)  The Severance Benefits referred to above will be in addition to,
and not in substitution for, any accrued and unpaid salary, vacation, pension or
other similar retirement benefits, and unreimbursed expenses to which you may be
otherwise entitled.

     7.   Change in Control.
          -----------------

          (a)  For purposes of this Agreement, "Change in Control" means and
shall be deemed to occur if any of the following occurs:  (i) the acquisition by
an individual, entity or group, as defined in Section 13(d)(3) or 14(d)(2) of
the Securities Exchange Act of 1934, as amended (the "Exchange Act"), of
beneficial ownership, as defined in Rule 13d-3 promulgated under the Exchange
Act, of 50% or more of either (A) the outstanding shares of common stock, $.01
par value per share, of the Company (the "Common Stock"), or (B) the combined
voting power of the voting securities of the Company entitled to vote generally
in the election of directors (the "Voting Securities"); or (ii) individuals who,
on November 21, 1997, constituted the Board of Directors of the Company (the
"Incumbent Board") cease for any reason to constitute at least a majority of the
Board of Directors of the Company; provided, however, that
                                   --------  -------

                                      A-7
<PAGE>

any individual becoming a director subsequent to November 21, 1997, whose
election, or nomination for election by the Company's shareholders, was approved
by a vote of at least a majority of the directors then serving and comprising
the Incumbent Board shall be considered as though such individual were a member
of the Incumbent Board, but excluding, for this purpose, any such individual
whose initial assumption of office occurs as a result of either an actual or
threatened election contest (as such terms are used in Rule 14a-11 of Regulation
14A promulgated under the Exchange Act) or other actual or threatened
solicitation of proxies or consents; or (iii) approval by the Board of Directors
or the shareholders of the Company of a (A) tender offer to acquire any of the
Common Stock or voting securities, (B) reorganization, (C) merger or (D)
consolidation, other than a reorganization, merger or consolidation with respect
to which all or substantially all of the individuals and entities who were the
beneficial owners, immediately prior to such reorganization, merger or
consolidation, of the Common Stock and voting securities beneficially own,
directly or indirectly, immediately after such reorganization, merger or
consolidation, more than 80% of the then outstanding common stock and voting
securities (entitled to vote generally in the election of directors) of the
Company resulting from such reorganization, merger or consolidation in
substantially the same proportions as their respective ownership, immediately
prior to such reorganization, merger or consolidation, of the Common Stock and
the voting securities; or (iv) Approval by the Board of Directors or the
shareholders of the Company of (A) a complete or substantial liquidation or
dissolution of the Company, or (B) the sale or other disposition of all or
substantially all of the assets of the Company, excluding a reorganization of
the Corporation under the corporate laws of Delaware.

          (b)  In the event of your actual termination of employment
contemporaneous with or following a Change in Control, except (x) because of
your death, (y) by the Company for Cause or Disability (as hereinafter defined)
or (z) by you other than for Good Reason (as hereinafter defined):  (i) you
shall be entitled to receive, in lieu of the sums described in Section 6, an
amount equal to 100% of the Severance Benefits due and determined as if payable
under Section 6 above, for each full year or portion thereof you have been
employed by the Company, up to a maximum of 100% of the Severance Benefits
mentioned in Section 6 above, to be paid in accordance with the terms of this
Agreement;  and (ii) the following additional provisions shall apply (which
provisions shall supersede any other provisions of the Agreement, including but
not limited to Section 2 of the Agreement, to the extent such provisions are
inconsistent with the following provisions):

               (1)  Disability.  For purposes of this Section 7(b), termination
                    ----------
by the Company of your employment based on "Disability" shall mean termination
because of your absence from your duties with the Company on a full time basis
for one hundred eighty (180) consecutive days as a result of your incapacity due
to physical or mental illness, unless within thirty (30) days after Notice of
Termination (as hereinafter defined) is given to you following such absence, you
shall have returned to the full time performance of your duties.

               (2)  Good Reason.  Termination by you of your employment for
                    -----------
"Good Reason" shall mean termination based on:

                                      A-8
<PAGE>

                    (A)  a reduction by the Company (within two years following
the Change of Control) in your Base Salary as in effect immediately prior to the
Change in Control, other than a reduction in salaries generally for officers of
the Company;

               (3)  Notice of Termination.  Any purported termination by the
                    ---------------------
Company or by you following a Change in Control shall be communicated by written
notice to the other party hereto which indicates the specific termination
provision in this Agreement relied upon (the "Notice of Termination").

               (4)  Date of Termination.  "Date of Termination" following a
                    -------------------
Change in Control shall mean (A) if your employment is to be terminated for
Disability, thirty (30) days after Notice of Termination is given (provided that
you shall not have returned to the performance of your duties on a full-time
basis during such thirty (30) day period), (B) if your employment is to be
terminated by the Company for any reason other than death or Disability or by
you pursuant to Sections 7(b)(2)(F) or 7(b)(6) hereof or for any other Good
Reason, the date specified in the Notice of Termination, or (C) if your
employment is terminated on account of your death, the day after your death.

               (5)  Compensation Upon Termination or During Disability; Other
                    ---------------------------------------------------------
Agreements.
----------

                    (A)  During any period following a Change in Control of the
Company that you fail to perform your duties as a result of incapacity due to
physical or mental illness, you shall continue to receive your Base Salary at
the rate then in effect and any benefits or awards under any Plan shall continue
to accrue during such period, to the extent not inconsistent with such Plans,
until and unless your employment is terminated pursuant to and in accordance
with this Section 7(b). Thereafter, your benefits shall be determined in
accordance with the Plans then in effect.

                    (B)  If your employment is terminated for Cause following a
Change in Control of the Company, the Company shall pay to you your Base Salary
through the Date of Termination at the rate in effect just prior to the time a
Notice of Termination is given plus any benefits or awards (including both the
cash and stock components) which pursuant to the terms of any Plans have been
earned or become payable, but which have not yet been paid to you. Thereupon,
the Company shall have no further obligations to you under this Agreement.

               (6)  Successors, Binding Agreement.
                    -----------------------------

                    (A)  The Company will seek, by written request at least five
(5) business days prior to the time a Person becomes a Successor (as hereinafter
defined), to have such Person, by agreement in form and substance satisfactory
to you, assent to the fulfillment of the Company's obligations under this
Agreement. Failure of such Person to furnish such assent by the later of (i)
three (3) business days prior to the time such Person becomes a Successor or

                                      A-9
<PAGE>

(ii) two (2) business days after such Person receives a written request to so
assent shall constitute Good Reason for termination by you of your employment if
a Change in Control of the Company occurs or has occurred. For purposes of
Section 7, "Successor" shall mean any person that succeeds to, or has the
practical ability to control, the Company's business directly, by merger or
consolidation, or indirectly, by purchase of the Company's securities eligible
to vote for the election of directors, or otherwise.

                    (B)  This Agreement shall inure to the benefit of and be
enforceable by your personal legal representatives, executors, administrators,
successors, heirs, distributees, devisees and legatees. If you should die while
any amount would still be payable to you hereunder if you had continued to live,
all such amounts, unless otherwise provided herein, shall be paid in accordance
with the terms of this Agreement to your devisee, legatee or other designee or,
if no such designee exists, to your estate.

                    (C)  For purposes of Section 7, the "Company" shall include
any subsidiaries of the Company and any corporation or other entity which is the
surviving or continuing entity in respect of any merger, consolidation or form
of business combination in which the Company ceases to exist; provided, however,
for purposes of determining whether a Change in Control has occurred herein, the
term "Company" shall refer to Applied Science and Technology, Inc. or its
Successor(s).

               (7)  Fees and Expenses; Mitigation.
                    -----------------------------

                    (A)  The Company shall reimburse you, on a current basis,
for all reasonable legal fees and related expenses incurred by you in connection
with the Agreement following a Change in Control of the Company, including
without limitation, (i) all such fees and expenses, if any, incurred in
contesting or disputing any termination of your employment or (ii) your seeking
to obtain or enforce any right or benefit provided by this Agreement, in each
case, regardless of whether or not your claim is upheld by a court of competent
jurisdiction; provided, however, you shall be required to repay any such amounts
to the Company to the extent that a court issues a final and non-appealable
order setting forth the determination that the position taken by you was
frivolous or advanced by you in bad faith.

                    (B)  You shall not be required to mitigate the amount of any
payment the Company becomes obligated to make to you in connection with this
Agreement, by seeking other employment or otherwise.

               (8)  Taxes.  All payments to be made to you under this Agreement
                    -----
will be subject to required withholding of federal, state and local income and
employment taxes.

          (c)  Notwithstanding any other provision of this Agreement, in the
event that any payment or benefit received or to be received by you as a result
of or in connection with a Change in Control, whether pursuant to the terms of
this Agreement or any other plan,

                                     A-10
<PAGE>

arrangement or agreement with the Company (all such payment and benefits being
hereinafter called the "Total Payments") would subject you to the excise tax
(the "Excise Tax") imposed under Section 4999 of the Internal Revenue Code of
1986, as amended (the "Code"), then, to the extent necessary to eliminate any
such imposition of the Excise Tax (after taking into account any reduction in
the Total Payments in accordance with the provisions of any other plan,
arrangement or agreement, if any), (a) any non-cash severance payments otherwise
payable to you shall first be reduced (if necessary, to zero), and (b) any cash
severance payment otherwise payable to you shall next be reduced. For purposes
of the immediately preceding sentence, (i) no portion of the Total Payments the
receipt or enjoyment of which you shall have effectively waived in writing shall
be taken into account, (ii) no portion of the Total Payment shall be taken into
account which in the opinion of nationally-recognized certified public
accountants (in each case as mutually selected by you and the Company) does not
constitute a "parachute payment" within the meaning of Section 280G of the Code,
including, without limitation, by reason of Section 280G(b)(2) or (b)(4)(A) of
the Code, (iii) any payments to you shall be reduced only to the extent
necessary so that the Total Payments [other than those referred to in clauses
(i) and (ii)] in their entirety constitute reasonable compensation for services
actually rendered within the meaning of Section 280G(4)(B) of the Code or are
otherwise not subject to disallowance as deductions, in the opinion of the tax
counsel or the accountants referred to in clause (ii); and (iv) the value of any
non-cash benefit or any deferred payment or benefit included in the Total
Payments shall be determined by such accountants in accordance with the
requirements of section 280G(d)(3) and (4) of the Code (and such determination
shall be reviewed by such tax counsel).

                     [THIS SPACE INTENTIONALLY LEFT BLANK]

                                     A-11
<PAGE>

                                                                       EXHIBIT B
                                                                       ---------



                   OUTSIDE EMPLOYMENTS AND DIRECTORSHIPS OF

                                JACK J. SCHUSS

                                      B-1
<PAGE>

                                                                       EXHIBIT C
                                                                       ---------

               ------------------------------------------------

               PROPRIETARY INFORMATION AND INVENTIONS AGREEMENT

               ------------------------------------------------

To:  Applied Science and Technology, Inc.
     35 Cabot Road
     Woburn, Massachusetts  01801

                                                As of February 1, 2000

     The undersigned, in consideration of and as a condition of my employment or
continued employment by you and/or by companies which you own, control, or are
affiliated with or their successors in business (collectively, the "Company"),
hereby agrees as follows:

     1.  Confidentiality.  I agree to keep confidential, except as the Company
         ---------------
may otherwise consent in writing, and, except for the Company's benefit, not to
disclose or make any use of at any time either during or subsequent to my
employment, any Inventions (as hereinafter defined), trade secrets, confidential
information, knowledge, data or other information of the Company relating to
products, processes, know-how, designs, formulas, test data, customer lists,
business plans, marketing plans and strategies, pricing strategies, or other
subject matter pertaining to any business of the Company or any of its
affiliates, which I may produce, obtain, or otherwise acquire during the course
of my employment, except as herein provided.  I further agree not to deliver,
reproduce or in any way allow any such trade secrets, confidential information,
knowledge, data or other information, or any documentation relating thereto, to
be delivered to or used by any third parties without specific direction or
consent of a duly authorized representative of the Company. There shall be no
restrictions applicable to trade secrets, confidential information, knowledge,
data or other information or portions thereof, or any other information supplied
by the Company which: (i) was in the undersign's possession prior to receipt
from the Company; (ii) has been or is rightfully obtained from a third party;
(iii) is or becomes publicly available other than through the fault or
negligence of the undersigned; or (iv) has been or is released without
restriction by the Company.

2.   Conflicting Employment; Return of Confidential Material. I agree that
     --------------------------------------------------------
during my employment with the Company I will not engage in any other employment,
occupation, consulting or other activity relating to the business in which the
Company is now or may hereafter become engaged, or which would otherwise
conflict with my obligations to the Company. In the event my employment with the
Company terminates for any reason whatsoever, I agree to promptly surrender and
deliver to the Company all records, materials, equipment, drawings, documents
and data of which I may obtain or produce during the course of my employment,
and I will not take with me any description containing or pertaining to any
confidential information, knowledge or data of the Company which I may produce
or obtain

                                      C-1
<PAGE>

during the course of my employment.

     3.   Assignment of Inventions.
          ------------------------

          3.1  I hereby acknowledge and agree that the Company is the owner of
all Inventions.  In order to protect the Company's rights to such Inventions, by
executing this Agreement I hereby irrevocably assign to the Company all my
right, title and interest in and to all Inventions to the Company.

          3.2  For purposes of this Agreement, "Inventions" shall mean all
discoveries, processes, designs, technologies, devices, or improvements in any
of the foregoing or other ideas, whether or not patentable and whether or not
reduced to practice, made or conceived by me (whether solely or jointly with
others) during the period of my employment with the Company which relate in any
manner to the actual or demonstrably anticipated business, work, or research and
development of the Company, or result from or are suggested by any task assigned
to me or any work performed by me for or on behalf of the Company.

          3.3  Any discovery, process, design, technology, device, or
improvement in any of the foregoing or other ideas, whether or not patentable
and whether or not reduced to practice, made or conceived by me (whether solely
or jointly with others) which I develop entirely on my own time not using any of
the Company's equipment, supplies, facilities, or trade secret information
("Personal Invention") is excluded from this Agreement provided such Personal
Invention (a) does not relate to the actual or demonstrably anticipated
business, research and development of the Company, and (b) does not result,
directly or indirectly, from any work performed by me for the Company.

     4.   Disclosure of Inventions.  I agree that in connection with any
          ------------------------
Invention, I will promptly disclose such Invention to my immediate superior at
the Company in order to permit the Company to enforce its property rights to
such Invention in accordance with this Agreement.  My disclosure shall be
received in confidence by the Company.

     5.   Patents and Copyrights; Execution of Documents.
          ----------------------------------------------

          5.1  Upon request, I agree to assist the Company or its nominee (at
its expense) during and at any time subsequent to my employment in every
reasonable way to obtain for its own benefit patents and copyrights for
Inventions in any and all countries.  Such patents and copyrights shall be and
remain the sole and exclusive property of the Company or its nominee.  I agree
to perform such lawful acts as the Company deems to be necessary to allow it to
exercise all right, title and interest in and to such patents and copyrights.

          5.2  In connection with this Agreement, I agree to execute,
acknowledge and deliver to the Company or its nominee upon request and at its
expense all documents, including assignments of title, patent or copyright
applications, assignments of such applications, assignments of patents or
copyrights upon issuance, as the Company may determine necessary or

                                      C-2
<PAGE>

desirable to protect the Company's or its nominee's interest in Inventions,
and/or to use in obtaining patents or copyrights in any and all countries and to
vest title thereto in the Company or its nominee to any of the foregoing.

     6.   Maintenance of Records.  I agree to keep and maintain adequate and
          ----------------------
current written records of all Inventions made by me (in the form of notes,
sketches, drawings and other records as may be specified by the Company), which
records shall be available to and remain the sole property of the Company at all
times.

     7.   Prior Inventions.  It is understood that all Personal Inventions, if
          ----------------
any, whether patented or unpatented, which I made prior to my employment by the
Company, are excluded from this Agreement.  To preclude any possible
uncertainty, I have set forth on Schedule A attached hereto a complete list of
all of my prior Personal Inventions, including numbers of all patents and patent
applications and a brief description of all unpatented Personal Inventions which
are not the property of a previous employer.  I represent and covenant that the
list is complete and that, if no items are on the list, I have no such prior
Personal Inventions.  I agree to notify the Company in writing before I make any
disclosure or perform any work on behalf of the Company which  appears to
threaten or conflict with proprietary rights I claim in any Personal Invention.
In the event of my failure to give such notice, I agree that I will make no
claim against the Company with respect to any such Personal Invention.

     8.   Other Obligations.  I acknowledge that the Company from time to time
          -----------------
may have agreements with other persons or with the U.S. Government or agencies
thereof, which impose obligations or restrictions on the Company regarding
Inventions made during the course of work thereunder or regarding the
confidential nature of such work.  I agree to be bound by all such obligations
and restrictions and to take all action necessary to discharge the Company's
obligations.

     9.   Trade Secrets of Others.  I represent that my performance of all the
          -----------------------
terms of this Agreement and as an employee of the Company does not and will not
breach any agreement to keep confidential proprietary information, knowledge or
data acquired by me in confidence or in trust prior to my employment with the
Company, and I will not disclose to the Company, or induce the Company to use,
any confidential or proprietary information or material belonging to any
previous employer or others.  I agree not to enter into any agreement either
written or oral in conflict herewith.

     10.  Modification.  I agree that any subsequent change or changes in my
          ------------
employment duties, salary or compensation or, if applicable, in any Employment
Agreement between the Company and me, shall not affect the validity or scope of
this Agreement.

     11.  Successors and Assigns.  This Agreement shall be binding upon my
          ----------------------
heirs, executors, administrators or other legal representatives and is for the
benefit of the Company, its successors and assigns.

                                      C-3
<PAGE>

     12.  Interpretation.  IT IS THE INTENT OF THE PARTIES THAT in case any one
          --------------
or more of the provisions contained in this Agreement shall, for any reason, be
held to be invalid, illegal or unenforceable in any respect, such invalidity,
illegality or unenforceability shall not affect the other provisions of this
Agreement, and this Agreement shall be construed as if such invalid, illegal or
unenforceable provision had never been contained herein.  MOREOVER, IT IS THE
INTENT OF THE PARTIES THAT in case any one or more of the provisions contained
in this Agreement shall for any reason be held to be excessively broad as to
duration, geographical scope, activity or subject, such provision shall be
construed by limiting and reducing it in accordance with a judgment of a court
of competent jurisdiction, so as to be enforceable to the extent compatible with
applicable law.

     13.  Waivers.  If either party should waive any breach of any provision of
          -------
this Agreement, he or it shall not thereby be deemed to have waived any
preceding or succeeding breach of the same or any other provision of this
Agreement.

     14.  Complete Agreement, Amendments.  I acknowledge receipt of this
          ------------------------------
Agreement, and agree that with respect to the subject matter thereof the
provisions of this Key Employee Agreement of which this Exhibit C is one part,
is my entire agreement with the Company, superseding any previous oral or
written communications, representations, understandings, or agreements with the
Company or any officer or representative thereof.  Any amendment to this
Agreement or waiver by either party of any right hereunder shall be effective
only if evidenced by a written instrument executed by the parties hereto, and,
in the case of the Company, upon written authorization of the Company's Board of
Directors.

     15.  Headings. The headings of the sections hereof are inserted for
          --------
convenience only and shall not be deemed to constitute a part hereof nor to
affect the meaning thereof.

     16.  Counterparts.  This Agreement may be signed in two counterparts, each
          ------------
of which shall be deemed an original and both of which shall together constitute
one agreement.

     17.  Governing Law.   This Agreement shall be governed by and construed
          -------------
under Massachusetts law.

                                      C-4
<PAGE>

     18   Employment Status.  Nothing in this Agreement shall affect in any
          -----------------
manner whatsoever the right or power of the Company to terminate the employment
of the Employee.

                                          EMPLOYEE



                                          /s/ Jack J. Schuss
                                          --------------------------------------
                                          Jack J. Schuss

Accepted and Agreed:
APPLIED SCIENCE AND TECHNOLOGY,  INC.



By: /s/ Dr. Richard S. Post
   ----------------------------------
   Dr. Richard S. Post, President

                                      C-5
<PAGE>

                                                                      SCHEDULE A
                                                                      ----------



                           LIST OF PRIOR INVENTIONS
                                      OF
                                JACK J. SCHUSS



                                                          Identifying Number or
Title                     Date                              Brief Description
-----                     ----                            ----------------------

                                      C-6
<PAGE>

                                        EXHIBIT D-1 (Incentive Stock Option)
                                        ------------------------------------

                     APPLIED SCIENCE AND TECHNOLOGY, INC.
                                 35 Cabot Road
                          Woburn, Massachusetts 01801

                                              Effective: February 1, 2000


Jack J. Schuss
8 Cedar Street
Newton, MA  02459

Dear Jack:

     I am pleased to advise you that APPLIED SCIENCE AND TECHNOLOGY, INC. (the
"Company") has, pursuant to its 1993 Stock Option Plan (the "1993 Plan"),
awarded you an incentive stock option to purchase [Note: The total grant of
30,000 shares will be divided between incentive stock options and non-qualified
options.  The incentive stock options will equal (a) the number of option shares
not to exceed $100,000 in value based on exercise price vesting in any single
calendar year, multiplied by (b) five (the five calendar years over which the
option vests).  The remaining options will be issued under a non-qualified stock
option - see attached] shares of the Common Stock, $.01 par value per share, of
the Company at an exercise price of $30.375 per share, for a total exercise
price of $911,250.00.  The Company is making this offer to "share the business"
with valued employees such as yourself.  We hope that by owning a piece of the
Company you will continue your efforts towards helping the Company grow and
succeed.

     The following terms and conditions are applicable with respect to this
option, and your signature below shall constitute your acknowledgment and
acceptance of same:

     (a)  This option shall not be transferable under any circumstances except
          by operation of law.  During your lifetime, this option is only
          exercisable by you, and after your death, is only exercisable by your
          estate.

     (b)  The price at which this option may be exercised shall be $30.375 per
          share, for a total exercise price of $911,250.00.

     (c)  This option is exercisable commencing six months from your hire date
          and at any time hereafter through February 1, 2005, subject to the
          following terms:

          (1)  In the event of termination of your employment with the Company
               (or a
<PAGE>

               parent or subsidiary of the Company) for any reason other than
               death or disability as defined in Internal Revenue Code Section
               22(e)(3), as amended (the "Code"), all unexercised options shall
               terminate immediately.

          (2)  In the event of termination of your employment as a result of
               your death, the outstanding options exercisable by you at the
               date of your death may be exercised by your estate until one (1)
               year from the date of your death, but in any event no later than
               February 1, 2005.

          (3)  In the event of termination of your employment as a result of
               your disability, as above defined, or in the event of a
               disability that lasts for more than ninety (90) days, all
               outstanding options exercisable by you at the date of such
               termination shall terminate one (1) year from the date your
               employment terminates, but in any event no later than February 1,
               2005.

          (4)  Notwithstanding anything herein to the contrary, the maximum
               extent to which this option may be exercised is as follows:

                    Dates                                  Up to
                    -----                                  -----

               After six (6) months of employment           20%
               After one (1) year of employment             40%
               After two (2) years of employment            60%
               After three (3) years of employment          80%
               After four (4) years of employment          100%


     (d)  This option may not be exercised as to less than one hundred (100)
          shares at any one time unless it is being exercised in full and the
          balance of the shares subject to this option is less than one hundred
          (100).

     (e)  The shares of Common Stock underlying this option and the exercise
          price therefore shall be appropriately adjusted from time to time for
          stock splits, reverse splits, stock dividends and reclassifications of
          shares.

     (f)  In the event of a sale or acquisition of substantially all of the
          stock or assets of the Company, the Company shall give at least thirty
          (30) days' notice of such an event to you and you may exercise up to
          100% of the vested portion of this option; if you do not exercise the
          option within thirty (30) days of such notice, all unexercised
          portions of this option shall terminate and be of no further force or
          effect.  Notwithstanding the foregoing, additional shares underlying
          this option
<PAGE>

          grant may vest in accordance with the provisions of Exhibit A of your
          Employment Agreement of even date with the Company.


     This opportunity to purchase stock in the Company is being offered because
of the Company's desire to reward continuing loyal service.  Exercising options
may not be a prudent business decision for some employees.  Therefore, we urge
you to review this opportunity carefully and make a decision to exercise options
only if your personal financial situation makes this a wise choice.

     When you wish to exercise this stock option, please refer to the provisions
of this letter and then correspond in writing with the Secretary of the Company.
Further, please indicate your acknowledgment and acceptance of this option by
signing the enclosed copy of this letter and returning it to the undersigned.

                              Very truly yours,

                              APPLIED SCIENCE AND TECHNOLOGY, INC.



                              By: /s/ John M. Tarrh
                                 -------------------------------------
                                  John M. Tarrh, Senior Vice President


ACKNOWLEDGMENT AND ACCEPTANCE:



/s/ Jack J. Schuss
-----------------------------
Jack J. Schuss

<PAGE>

                                    EXHIBIT E (Non-Qualified Option)
                                    --------------------------------

                     APPLIED SCIENCE AND TECHNOLOGY, INC.
                                 35 Cabot Road
                          Woburn, Massachusetts 01801


                                         Effective: February 1, 2000


Jack J. Schuss
8 Cedar Street
Newton, MA 02459

Dear Jack:

     I am pleased to advise you that APPLIED SCIENCE AND TECHNOLOGY, INC. (the
"Company") has, pursuant to its 1993 Stock Option Plan (the "1993 Plan"),
awarded you a non-qualified stock option to purchase [Note: Remainder of 30,000
option grant not qualifying for incentive stock option treatment] shares of the
Common Stock, $.01 par value per share, of the Company at an exercise price of
$30.375 per share, for a total exercise price of $911,250.00. The Company is
making this offer to "share the business" with valued employees such as
yourself.  We hope that by owning a piece of the Company you will continue your
efforts towards helping the Company grow and succeed.

     The following terms and conditions are applicable with respect to this
option, and your signature below shall constitute your acknowledgment and
acceptance of same:

     (a)  This option shall not be transferable under any circumstances except
          by operation of law.  During your lifetime, this option is only
          exercisable by you, and after your death, is only exercisable by your
          estate.

     (b)  The price at which this option may be exercised shall be $30.375 per
          share, for a total exercise price of $911,250.00.

     (c)  This option is exercisable commencing six months from your hire date
          and at any time hereafter through February 1, 2005, subject to the
          following terms:

          (1)  In the event of termination of your employment with the Company
               (or a parent or subsidiary of the Company) for any reason other
               than death or disability as defined in Internal Revenue Code
               Section 22(e)(3), as amended (the "Code"), all unexercised
               options shall terminate immediately.
<PAGE>

          (2)  In the event of termination of your employment as a result of
               your death, the outstanding options exercisable by you at the
               date of your death may be exercised by your estate until one (1)
               year from the date of your death, but in any event no later than
               February 1, 2005.

          (3)  In the event of termination of your employment as a result of
               your disability, as above defined, or in the event of a
               disability that lasts for more than ninety (90) days, all
               outstanding options exercisable by you at the date of such
               termination shall terminate one (1) year from the date your
               employment terminates, but in any event no later than February 1,
               2005.

          (4)  Notwithstanding anything herein to the contrary, the maximum
               extent to which this option may be exercised is as follows:

                    Dates                                   Up to
                    -----                                   -----

               After six (6) months of employment            20%
               After one (1) year of employment              40%
               After two (2) years of employment             60%
               After three (3) years of employment           80%
               After four (4) years of employment           100%

     (d)  This option may not be exercised as to less than one hundred (100)
          shares at any one time unless it is being exercised in full and the
          balance of the shares subject to this option is less than one hundred
          (100).

     (e)  The shares of Common Stock underlying this option and the exercise
          price therefore shall be appropriately adjusted from time to time for
          stock splits, reverse splits, stock dividends and reclassifications of
          shares.

     (f)  In the event of a sale or acquisition of substantially all of the
          stock or assets of the Company, the Company shall give at least thirty
          (30) days' notice of such an event to you and you may exercise up to
          100% of the vested portion of this option; if you do not exercise the
          option within thirty (30) days of such notice, all unexercised
          portions of this option shall terminate and be of no further force or
          effect.  Notwithstanding the foregoing, additional shares underlying
          this option grant may vest in accordance with the provisions of
          Exhibit A of your Employment Agreement of even date with the Company.


     This opportunity to purchase stock in the Company is being offered because
of the Company's desire to reward continuing loyal service.  Exercising options
may not be a prudent
<PAGE>

business decision for some employees. Therefore, we urge you to review this
opportunity carefully and make a decision to exercise options only if your
personal financial situation makes this a wise choice.

     When you wish to exercise this stock option, please refer to the provisions
of this letter and then correspond in writing with the Secretary of the Company.
Further, please indicate your acknowledgment and acceptance of this option by
signing the enclosed copy of this letter and returning it to the undersigned.

                                   Very truly yours,

                                   APPLIED SCIENCE AND TECHNOLOGY, INC.



                                   By: /s/ John M. Tarrh
                                      ------------------------------------------
                                      John M. Tarrh, Senior Vice President


ACKNOWLEDGMENT AND ACCEPTANCE:



/s/ Jack J. Schuss
--------------------------------
Jack J. Schuss