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                               ASECO CORPORATION

                     1993 NON-EMPLOYEE DIRECTOR STOCK PLAN
            (Amended and Restated Effective as of August 11, 1998)

     1.   Purpose.  This plan, to be known as the 1993 Non-Employee Director
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Stock Plan (hereinafter, this "Plan") is intended to promote the interests of
Aseco Corporation (hereinafter, the "Company") by providing an inducement to
obtain and retain the services of qualified persons who are not employees or
officers of the Company to serve as members of its Board of Directors (the
"Board").

     2.   Available Shares.  The total number of shares of Common Stock, par
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value $.01 per share, of the Company (the "Common Stock"), which may be granted
under this Plan shall not exceed 165,000 shares, subject to adjustment in
accordance with paragraph 10 of this Plan.  Shares subject to this Plan are
authorized but unissued shares or shares that were once issued and subsequently
reacquired by the Company.  If any options granted under this Plan are
surrendered before exercise or lapse without exercise, in whole or in part, the
shares reserved therefor shall continue to be available under this Plan.

     3.   Administration.  This Plan shall be administered by the Board or by a
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committee appointed by the Board (the "Committee"). In the event the Board fails
to appoint or refrains from appointing a Committee, the Board shall have all
power and authority to administer this Plan.  In such event, the word
"Committee" wherever used herein shall be deemed to mean the Board.  The
Committee shall, subject to the provisions of the Plan, have the power to
construe this Plan, to determine all questions hereunder, and to adopt and amend
such rules and regulations for the administration of this Plan as it may deem
desirable.

     4.   Granting of Options.
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          (a) Initial Grant.  On the effective date of a registration statement
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on Form S-1 covering the initial public offering of the Company's Common Stock
(the "Effective Date"), each person who is then a member of the Board, and who
is not a current or former employee or officer of the Company, shall be
automatically granted, without further action by the Board, an option to
purchase 3,000 shares of the Common Stock.

          (b) Initial Grant to New Directors.  Subject to the availability of
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shares under this Plan, each person who is first elected as a member of the
Board after May 15, 1996 and during the term of this Plan, and who is not on the
date of such election a current or former employee or officer of the Company,
shall be automatically granted an option to purchase 15,000 shares of the Common
Stock on the date of his or her first election as a member of the Board.
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          (c) Automatic Grants.  On April 30 of each year commencing April 30,
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1996 and during the term of this Plan, each person who is then serving on the
Board, and who is not a current or former employee or officer of the Company,
shall automatically be granted an option to purchase 3,500 shares of the Common
Stock, subject to the availability of shares under this Plan.

          (d) Initial Option Adjuster.  On May 15, 1996, each person who is
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serving on the Board as of such date, who is not a current or former employee or
officer of the Company and who is to serve on the Board following the 1996
Annual Meeting of Stockholders of the Company shall automatically be granted an
option to purchase an additional 10,000 shares of Common Stock.

     Except for the specific options referred to above, no other options shall
be granted under this Plan.

     5.   Option Price.  The purchase price of the stock covered by an option
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granted pursuant to this Plan shall be 100% of the fair market value of such
shares on the day the option is granted.  The option price will be subject to
adjustment in accordance with the provisions of paragraph 10 of this Plan.  For
purposes of this Plan, if, at the time an option or Stock Award (defined below)
is granted under the Plan, the Company's Common Stock is publicly traded, "fair
market value" shall be determined as of the last business day for which the
prices or quotes discussed in this sentence are available prior to the date such
option or Stock Award is granted and shall mean (i) the average (on that date)
of the high and low prices of the Common Stock on the principal national
securities exchange on which the Common Stock is traded, if the Common Stock is
then traded on a national securities exchange; or (ii) the last reported sale
price (on that date) of the Common Stock on the Nasdaq National Market System,
if the Common Stock is not then traded on a national securities exchange; or
(iii) the closing bid price (or average of bid prices) last quoted (on that
date) by an established quotation service for over-the-counter National Market
System. If, at the time an option or Stock Award is granted under the Plan, the
Company's stock is not publicly traded, "fair market value" shall be the fair
market value on the date the option or Stock Award is granted as determined by
the Board in good faith.

     6.   Period of Option.  Unless sooner terminated in accordance with the
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provisions of paragraph 8 of this Plan, an option granted hereunder shall expire
on the date which is ten (10) years after the date of grant of the option.

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<PAGE>
 
     7.   Vesting of Shares and Non-Transferability of Options.
          ---------------------------------------------------- 

          (a) Vesting.  Options granted under this Plan shall not be exercisable
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until they become vested.  Options granted pursuant to Sections 4(b), 4(c) and
4(d) of this Plan shall vest in the optionee and thus become exercisable
immediately by the optionee in two annual installments of 50% each on the first
and second anniversary of the date of grant.  Options granted pursuant to
Section 4(a) of the Plan shall be 100% vested on the date of grant and thus be
fully exercisable at any time prior to their expiration.

          (b) Legend on Certificates.  The certificates representing such shares
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shall carry such appropriate legend, and such written instructions shall be
given to the Company's transfer agent, as may be deemed necessary or advisable
by counsel to the Company in order to comply with the requirements of the
Securities Act of 1933 or any state securities laws.

          (c) Non-transferability.  Any option granted pursuant to this Plan
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shall not be assignable or transferable other than by will or the laws of
descent and distribution or pursuant to a domestic relations order and shall be
exercisable during the optionee's life time only by him or her.

     8.   Termination of Option Rights.
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          (a) In the event an optionee ceases to be a member of the Board for
any reason other than death or permanent disability, any then unexercised
portion of options granted to such optionee shall, to the extent not then
vested, immediately terminate and become void; any portion of an option which is
then vested but has not been exercised at the time the optionee so ceases to be
a member of the Board may be exercised, to the extent it is then vested, by the
optionee within two years of the date the optionee ceased to be a member of the
Board; and all options shall terminate after such two-year period has have
expired.

          (b) In the event that an optionee ceases to be a member of the Board
by reason of his or her death or permanent disability, any option granted to
such optionee shall be immediately, and automatically accelerated and become
fully vested and all unexercised options shall be exercisable by the optionee
(or by the optionee's personal representative, heir or legatee, in the event of
death) until the scheduled expiration date of the option.

     9.   Exercise of Option.  Subject to the terms and conditions of this Plan
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and the option agreements, an option granted hereunder shall, to the extent then
exercisable, be exercisable in whole or in part by giving written notice to the
Company by mail or in person addressed to Aseco Corporation, 500

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<PAGE>
 
Donald Lynch Boulevard, Marlboro, Massachusetts 01752, Attention: Chief
Financial Officer, stating the number of shares with respect to which the option
is being exercised, accompanied by payment in full for such shares. Payment may
be (a) in United States dollars in cash or by check, (b) in whole or in part in
shares of Common Stock of the Company already owned by the person or persons
exercising the option or shares subject to the option being exercised (subject
to such restrictions and guidelines as the Board may adopt from time to time),
valued at fair market value determined in accordance with the provisions of
paragraph 5 or (c) consistent with applicable law, through the delivery of an
assignment to the Company of a sufficient amount of the proceeds from the sale
of the Common Stock acquired upon exercise of the option and an authorization to
the broker or selling agent to pay that amount to the Company, which sale shall
be at the participant's direction at the time of exercise. There shall be no
such exercise at any one time as to fewer than one hundred (100) shares or all
of the remaining shares then purchasable by the person or persons exercising the
option, if fewer than one hundred (100) shares. The Company's transfer agent
shall, on behalf of the Company, prepare a certificate or certificates
representing such shares acquired pursuant to exercise of the option, shall
register the optionee as the owner of such shares on the books of the Company
and shall cause the fully executed certificates(s) representing such shares to
be delivered to the optionee as soon as practicable after payment of the option
price in full. The holder of an option shall not have any rights of a
stockholder with respect to the shares covered by the option, except to the
extent that one or more certificates for such shares shall be delivered to him
or her upon the due exercise of the option.

     10.  Adjustments Upon Changes in Capitalization and Other Matters.  Upon
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the occurrence of any of the following events, an optionee's rights with respect
to options granted to him or her hereunder shall be adjusted as hereinafter
provided:

          (a) If, after January 18, 1993, the shares of Common Stock shall be
subdivided or combined into a greater smaller number of shares or if the Company
shall issue any shares of Common Stock as a stock dividend on its outstanding
Common Stock, the number of shares of Common Stock deliverable upon the exercise
of options shall be appropriately increased or decreased proportionately, and
appropriate adjustments shall be made in the purchase price per share to reflect
such subdivision, combination or stock dividend.  No adjustment, however, shall
be made for the 1-for-2.4 reverse split of the Common Stock declared by the
Board on January 18, 1993.

          (b) Merger; Consolidation; Liquidation; Sale of Assets.  In the event
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the Company is merged into or consolidated with another corporation under
circumstances where the Company is not the surviving corporation, or if the
Company is liquidated or

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<PAGE>
 
sells or otherwise disposes of all or substantially all of its assets to another
corporation while unexercised options remain outstanding under the Plan, (i)
subject to the provisions of clauses (iii), (iv) and (v) below, after the
effective date of such merger, consolidation or sale, as the case may be, each
holder of an outstanding option shall be entitled, upon exercise of such option,
to receive in lieu of shares of Common Stock, shares of such stock or other
securities as the holders of shares of Common Stock received pursuant to the
terms of the merger, consolidation or sale; or (ii) the Board may waive any
discretionary limitations imposed with respect to the exercise of the option so
that all options from and after a date prior to the effective date of such
merger, consolidation, liquidation or sale, as the case may be, specified by the
Board, shall be exercisable in full; or (iii) all outstanding options may be
cancelled by the Board as of the effective date of any such merger,
consolidation, liquidation or sale, provided that notice of such cancellation
shall be given to each holder of an option, and each such holder thereof shall
have the right to exercise such option in full (without regard to any
discretionary limitations imposed with respect to the option) during a 30-day
period preceding the effective date of such merger, consolidation, liquidation
or sale; or (iv) all outstanding options may be cancelled by the Board as of the
date of any such merger, consolidation, liquidation or sale, provided that
notice of such cancellation shall be given to each holder of an option and each
such holder thereof shall have the right to exercise such option but only to the
extent exercisable in accordance with any discretionary limitations imposed with
respect to the option prior to the effective date of such merger, consolidation,
liquidation or sale; or (v) the Board may provide for the cancellation of all
outstanding options and for the payment to the holders thereof of some part or
all of the amount by which the value thereof exceeds the payment, if any, which
the holder would have been required to make to exercise such option.

          (c) Issuance of Securities.  Except as expressly provided herein, no
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issuance by the Company of shares of stock of any class, or securities
convertible into shares of stock of any class, shall affect, and no adjustment
by reason thereof shall be made with respect to, the number or price of shares
subject to options.  No adjustments shall be made for dividends paid in cash or
in property other than securities of the Company.

          (d) Adjustments.  Upon the happening of any of the foregoing events,
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the class and aggregate number of shares set forth in paragraph 2 of this Plan
that are subject to options which previously have been or subsequently may be
granted under this Plan shall also be appropriately adjusted to reflect such
events.  The Board shall determine the specific adjustments to be made under
this paragraph 10 and its determination shall be conclusive.

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<PAGE>
 
     11.  Restrictions on Issuance of Shares.  Notwithstanding the provisions of
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paragraphs 4, 9 and 14 of this Plan, the Company shall have no obligation to
deliver any certificate or certificates upon exercise of an option or grant of a
Stock Award until one of the following conditions shall be satisfied:

          (i) The shares with respect to the Stock Award or which the option has
been exercised are at the time of the issue of such shares effectively
registered under applicable Federal and state securities laws as now in force or
hereafter amended; or

          (ii) Counsel for the Company shall have given an opinion that such
shares are exempt from registration under Federal and state securities laws as
now in force or hereafter amended; and the Company has complied with all
applicable laws and regulations with respect thereto, including without
limitation all regulations required by any stock exchange upon which the
Company's outstanding Common Stock is then listed.

     12.  Representation of Optionee.  If requested by the Company, the optionee
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shall deliver to the Company written representations and warranties upon
exercise of the option that are necessary to show compliance with Federal and
state securities laws, including representations and warranties to the effect
that a purchase of shares under the option is made for investment and not with a
view to their distribution (as that term is used in Securities Act of 1933).

     13.  Option Agreement.  Each option granted under the provisions of this
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Plan shall be evidenced by an option agreement, which agreement shall be duly
executed and delivered on behalf for the Company and by the optionee to whom
such option is granted.  The option agreement shall contain such terms,
provisions and conditions not inconsistent with this Plan as may be determined
by the officer executing it.

     14.  Annual Stock Awards.  Subject to the availability of shares under this
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Plan, on the date of each annual meeting of the Company's stockholders,
commencing with the annual meeting of stockholders held on August 11, 1998, each
person who is then a member of the Board, and is not a current or former
employee or officer of the Company, shall be awarded a number of shares of
Common Stock determined by dividing 5,000 by the fair market value of one share
of Common Stock on such date ("Stock Awards").

     15.  Termination and Amendment of Plan.  Options and Stock Awards may no
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longer be granted under this Plan after January 18, 2003, and this Plan shall
terminate when all options granted or to be granted hereunder are no longer
outstanding.  The Board may at any time terminate this Plan or make such
modification or amendment thereof as it deems advisable; provided, however, that
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the Board may not, without approval by the affirmative vote of

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<PAGE>
 
the holders of a majority of the shares of Common Stock present in person or by
proxy and entitled to vote at the meeting, (a) increase the maximum number of
shares for which options and Stock Awards may be granted under this Plan (except
by adjustment pursuant to Section 10), (b) materially modify the requirements as
to eligibility to participate in this Plan, (c) materially increase benefits
accruing to participants under this Plan, or (d) amend this Plan in any manner
which would cause Rule 16b-3 to become inapplicable to this Plan; and provided
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further that the provisions of this Plan specified in Rule 16b-3(c)(2)(ii)(A)
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(or any successor or amended provision thereof) under the Securities Exchange
Act of 1934 (including without limitation, provisions as to eligibility, amount,
price and timing of awards) may not be amended more than once every six months,
other than to comport with changes in the Internal Revenue Code, the Employee
Retirement Income Security Act, or the rules thereunder. Termination or any
modification or amendment of this Plan shall not, without consent of a
participant, affect his or her rights under an option or Stock Award previously
granted to him or her.

     16.  Withholding of Income Taxes.  Upon the exercise of an option or grant
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of a Stock Award hereunder, the Company, in accordance with Section 3402(a) of
the Internal Revenue Code, may require the participant to pay withholding taxes
in respect of amounts considered to be compensation includible in the
participant's gross income.

     17.  Compliance with Regulations.  It is the Company's intent that the Plan
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comply with all respects with Rule 16b-3 under the Securities Exchange Act of
1934 (or any successor or amended version thereof) and any applicable Securities
and Exchange Commission interpretations thereof.  If any provision of this Plan
is deemed not to be in compliance with Rule 16b-3, the provision shall be null
and void.

     18.  Governing Law.  The validity and construction of this Plan and the
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instruments evidencing options shall be governed by the laws of The Commonwealth
of Massachusetts, without giving effect to the principles of conflicts of law
thereof.

Date Approved by Board of
Directors of the Company:           August 11, 1998

Date Approved by Stockholders
of the Company:                     
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