<PAGE>

Exhibit 10i

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

                        KEY EMPLOYEE AGREEMENT

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


To:  John Edward Ross                                       As of August 8, 2000
     2183 Shadow Ridge Way
     San Jose, CA  95138


     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:

     1.   Position and Responsibilities.
          -----------------------------

          1.1  You shall serve as President & Chief Operating Officer of the
Company which will officially be approved at the next Board of Directors
meeting.  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 Chief Executive Officer 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 are 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 Chief Executive
Officer, will be based out of the Company's Santa Clara office and, it is
anticipated that you will spend up to 50% of your time working at the
Wilmington, Massachusetts 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.

          2.2  The Company shall have the right, upon written notice to you, to
terminate

                                      A-1
<PAGE>

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 Chief Executive Officer of the Company provided
the same are not illegal, unethical or inconsistent with the position of
President & Chief Operating Officer 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
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) day's 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").

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

                                      A-2
<PAGE>

          4.1  Except for any outside employments and directorships currently
held by you as listed on Exhibit B, and except with the prior written consent of
                         ---------
the Company's Chief Executive 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.


     7.   Post Employment Activities.
          ---------------------------

          7.1  You agree that for a period of twelve (12) months commencing on
the

                                      A-3
<PAGE>

termination of your employment for any reason, you will not, directly or
indirectly in the states and territories of the United States, 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 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.

          7.2  You agree that during your employ and for a period of twelve (12)
months commencing on the termination of your employment for any reason, you
shall not, directly or indirectly, entice, solicit or encourage any Company
employee to leave the employ of the Company, nor shall you, directly or
indirectly, be involved in the recruitment of any Company employee.  You
acknowledge and agree that any and all "goodwill" associated with any customer
or account belongs exclusively to the Company including, but not limited to, any
goodwill created as a result of direct or indirect contacts or relationships
between yourself or the employees you supervise for the Company and any
customers or accounts of the Company.

     8.   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 10, 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.

     9.   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.

     10.  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

                                      A-4
<PAGE>

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.

     11.  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 agree 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 11 shall be deemed to be the date of delivery thereof.

     12.  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.

     13.  Complete Agreement; Amendments.  The foregoing including Exhibits A,
          ------------------------------
B, C and D 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.

     14.  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.

     15.  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.

     16.  Choice of Law; Enforceability; Waiver of Jury Trial.  John Edward Ross
          ---------------------------------------------------
acknowledges that a substantial portion of the Company's business is based out
of and directed from the Commonwealth of Massachusetts, where the Company is
headquartered and administers all employee compensation and benefits. John
Edward Ross also acknowledges that during the course of his employment with the
Company he has and will continue to have substantial contacts with
Massachusetts.

          This Agreement shall be deemed to have been made in the Commonwealth
of Massachusetts, shall take effect as an instrument under seal within
Massachusetts, and the validity, interpretation and performance of this
Agreement shall be governed by, and construed in accordance with, the internal
law of Massachusetts, without giving effect to conflict of law principles. Both
parties further acknowledge that the last act necessary to render this Agreement
enforceable is its execution by the Company in Massachusetts, and that the
Agreement thereafter shall be maintained in Massachusetts. Both parties agree
that any action, demand, claim or counterclaim relating to the terms and
provision of this Agreement, or to its breach, shall be

                                      A-5
<PAGE>

commenced in Massachusetts in a court of competent jurisdiction. Both parties
further acknowledge that venue shall exclusively lie in Massachusetts and that
material witnesses and documents would be located in Massachusetts. Both parties
further agree that any action, demand, claim or counterclaim shall be resolved
by a judge alone, and both parties hereby waive and forever renounce the right
to a trial before a civil jury.

     17.  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
Popeo, 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/ John Edward Ross               By:  /s/ Dr. Richard S. Post
------------------------------            --------------------------
(John Edward Ross)                        Dr. Richard S. Post, Chief Executive
                                          Officer

                                      A-6
<PAGE>

                                                                       EXHIBIT A
                                                                       ---------

                  EMPLOYMENT TERM, COMPENSATION AND BENEFITS
                              OF John Edward Ross

     1.   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
August 8, 2001.

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

          (a) Base Salary.  Your base salary ("Base Salary") shall be $9231.00
              -----------
payable on a bi-weekly basis ($240,006.00 on an annualized basis) through
September 30, 2001 payable in accordance with the Company's payroll policies.
Commencing October 1, 2001, 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 2001 which commences on July 1, 2000,
under which you shall be entitled to a bonus of up to 40% 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 65,000 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 in four equal annual installments on the anniversary date of such
grant.  A copy of the forms of option grant letter is attached hereto as
Exhibits D and E.  Notwithstanding the foregoing, in the event of a Change in
----------------
Control (as defined in Section 7 herein), 100% of such option shall vest
immediately prior but subject to the Change of Control.

                                      A-7
<PAGE>

     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.

     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 (with the exception of the termination of your employment
after a Change in Control either without Cause for non-performance reasons or
for Good Reason) a total amount equal to (100%) of your then current annual Base
Salary, or a pro-rated portion in the event that you start a full time position
with another company.  The Severance Benefits shall be paid via check to you in
(26) equal biweekly installments (or up until you start a full time position
with another company, whichever is sooner) commencing within ten (10) days after
the date of your termination of employment with the Company.  In the event of
the termination of your employment after a Change in Control either without
Cause for non-performance reasons or for Good Reason, you shall be entitled to
the Good Reason Severance Benefits identified in Section 7(b)(5)(C) below.

          (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 up to twelve (12)
months beginning on the Date of Termination.  Not withstanding the foregoing,
such Severance Benefits shall be reduced by any compensation you receive as an
employee or consultant from any third party during the Severance period.

          (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 (August 8, 2000), 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 any individual
                                   --------  -------
becoming a director subsequent to August 8, 2000, whose election, or nomination
for

                                      A-8
<PAGE>

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, at any time within eighteen (18) months following a
Change in Control, a termination based on:

                                      A-9
<PAGE>

                    (A)  a reduction by the Company in your Base Salary as in
                         effect immediately prior to the Change in Control,
                         other than a reduction in salaries generally for
                         managers of the Company; or
                    (B)  your becoming ineligible for participation in the
                         Management Bonus Plan; or
                    (C)  the Company relocating you (without your consent) to an
                         office or location more than 50 miles from the office
                         where you had been providing services to the company
                         immediately prior to the Change in Control; or
                    (D)  a substantial and material diminution of your position
                         or duties as they existed prior to the Change in
                         Control. The parties hereby agree that a change in your
                         title or reporting obligations after a Change in
                         Control shall not, in and of itself, be deemed to
                         constitute a for "Good Reason." The parties further
                         agree that, upon written notice of the Employee's
                         decision to terminate for Good Reason, the Company
                         shall have ten (10) days in which to cure such "Good
                         Reason."

               (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.

                                      A-10
<PAGE>

                    (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.

                    (C)  In the event of a Change in Control and your employment
is terminated for "Good Reason" or without "Cause" for non-performance reasons
(provided that, unless such non-performance relates to gross negligence or gross
incompetence, you have been given written notice of such non-performance by the
Board of Directors and 14 calendar days to cure such non-performance after
receipt of such notice) within eighteen (18) months of the Change in Control,
you shall be entitled to for "Good Reason Severance Benefits." When used in this
Agreement, the term "Good Reason Severance Benefits" shall mean a total amount
equal to one hundred percent (100%) of your then current annual Base Salary. The
Good Reason Severance Benefits shall be paid via check to you in twenty six (26)
equal biweekly installments commencing within ten (10) days after the date of
your termination of employment with the Company. It shall also include the
continuation for you and your family, during the one year Severance Period
following your Date of Termination, of all of the other benefits which are
provided or available to you on the last day of your actual service with the
Company. The Good Reason Severance Benefits 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.

               (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
(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

                                      A-11
<PAGE>

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, 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

                                      A-12
<PAGE>

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-13
<PAGE>

                                                                       EXHIBIT B
                                                                       ---------



                   OUTSIDE EMPLOYMENTS AND DIRECTORSHIPS OF
                               John Edward Ross



Director for Life Quality Products (business provides bottled water for cancer
patients)

                                      B-1
<PAGE>

                                                                       EXHIBIT C
                                                                       ---------

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

                PROPRIETARY INFORMATION AND INVENTIONS AGREEMENT

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

To:  Applied Science and Technology, Inc.
     90 Industrial Way
     Wilmington, Massachusetts  01887-4610

                                                 As of August 8, 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.

     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 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

                                      C-1
<PAGE>

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 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

                                      C-2
<PAGE>

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.

     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

                                      C-3
<PAGE>

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/ John Edward Ross
                                          ------------------------------------
                                          John Edward Ross


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 John Edward Ross



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

                                 NONE

                                      C-6
<PAGE>

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

                     APPLIED SCIENCE AND TECHNOLOGY, INC.
                               90 Industrial Way
                     Wilmington, Massachusetts  01887-4610

                                                                  August 8, 2000


John Edward Ross
2183 Shadow Ridge Way
San Jose, CA  95138

Dear John:

     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
65,000 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 $12.625 per share, for a total exercise
price of $820,625. 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.

     (c)  The price at which this option may be exercised shall be $12.625 per
          share, for a total exercise price of $820,625.00.

     (d)  This option is exercisable commencing on August 8,2000 and at any time
          hereafter through August 8, 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

                                      E-1
<PAGE>

               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
               August 8, 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 August 8,
               2005.

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

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

                    August 8, 2000                               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%


     (e)  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).

     (f)  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.

     (g)  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.

                                      E-2
<PAGE>

     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/ William S. Hurley
                                    ----------------------------------------
                                    William S. Hurley, Senior Vice President


ACKNOWLEDGMENT AND ACCEPTANCE:



/s/ John Edward Ross
------------------------------
John Edward Ross


                                      E-3
<PAGE>

                                    EXHIBIT E-1 (Non-Qualified Option)
                                    ----------------------------------

                     APPLIED SCIENCE AND TECHNOLOGY, INC.
                               90 Industrial Way
                     Wilmington, Massachusetts  01887-4610

                                                   August 8, 2000


John Edward Ross
2183 Shadow Ridge Way
San Jose, CA  95138

Dear John:

     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: Remainder of 65,000
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
$12.625 per share, for a total exercise price of $820,625. 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.

     (c)  The price at which this option may be exercised shall be $12.625 per
          share, for a total exercise price of $820,625.00.

     (d)  This option is exercisable commencing on August 8, 2000 and at any
          time hereafter through August 8, 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.

                                      E-4
<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
               August 8, 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 August 8,
               2005.

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

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

                 August 8, 2000                             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%


     (e)  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).

     (f)  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.

     (g)  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 business decision for some employees. Therefore, we urge
you to review this opportunity

                                       5
<PAGE>

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/ William S. Hurley
                                 -------------------------------------------
                                 William S. Hurley, Senior Vice President


ACKNOWLEDGMENT AND ACCEPTANCE:



/s/ John Edward Ross
------------------------------
John Edward Ross


                                      E-6