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                                                                  EXHIBIT 10.18
 
                              SEVERANCE AGREEMENT
 
  This Severance Agreement is entered into as of this 21st day of April, 1998
by and between Aseco Corporation, a Delaware corporation (the "Company"), and
Phillip J. Villari (the "Employee").
 
                                   Recitals:
 
  WHEREAS, the Employee is an executive officer of the Company; and
 
  WHEREAS, the Company and the Employee wish to provide for the payment of
certain severance compensation by the Company to the Employee in the event the
Employee's employment by the Company is terminated.
 
  NOW, THEREFORE, in consideration of the Employee's continued service to the
Company and other good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the parties agree as follows:
 
1. Definitions.
 
  "Benefit Period" shall mean the six (6)-month period following the
Termination Date.
 
  "Cause" shall be deemed to exist if the Board of Directors of the Company or
its successor in good faith determines, after giving the Employee notice and
an opportunity to be heard, that the Employee has committed an act
constituting fraud, embezzlement, larceny or theft.
 
  "Change in Control" shall mean (i) the sale, lease, transfer or other
disposition by the Company of all or substantially all of its assets in a
single transaction or a series of related transactions; (ii) the merger or
consolidation of the Company with another entity in which the stockholders of
the Company immediately prior to such merger or consolidation hold less than
50% of the outstanding voting stock of the surviving or resulting corporation
immediately following such transaction; or (iii) the sale or exchange (to or
with any person or entity other than the Company) by the stockholders of the
Company of more than 50% of the outstanding voting stock of the Company in a
single transaction or series of related transactions.
 
  "Ineligibility Period" shall mean that portion of the Benefit Period when
the Employee is ineligible for coverage under the Company's group life or
group health insurance policies.
 
  "Termination Date" shall mean the effective date of the termination of the
Employee's employment with the Company.
 
  2. Severance.
 
  In the event the Employee's employment by the Company is terminated without
Cause by the Company or any successor within twelve (12) months following a
Change in Control, the Company or such successor shall (i) pay the Employee
within five days after the Termination Date a lump sum amount equal to six (6)
times the Employee's monthly base salary in effect at the time of such
termination (less applicable withholding taxes and FICA) and (ii) continue to
provide during the Benefit Period life and health insurance coverage to the
Employee, with benefits substantially comparable to those provided to
executive officers of the Company generally immediately prior to such
termination. Notwithstanding the foregoing, the Company shall have the right,
in lieu of providing such coverage during any Ineligibility Period, to pay the
Employee an amount equal to 200% of the amount it would have cost the Company
to provide such coverage during any Ineligibility Period, assuming the
Employee were eligible for coverage under the Company's group insurance
policies and assuming further no increase in premium costs under such policies
after the commencement of the Ineligibility Period.
 
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  3. Miscellaneous.
 
  3.1 This Agreement constitutes the entire agreement between the parties and
supersedes all prior agreements and understandings, whether written or oral,
relating to the subject matter of this Agreement.
 
  3.2 This Agreement may be amended or modified only by a written instrument
executed by both the Company and the Employee.
 
  3.3 This Agreement shall be construed, interpreted and enforced in
accordance with the laws of The Commonwealth of Massachusetts.
 
  3.3a. Upon a "change of control" at any time after you join Aseco, the
vesting of all stock options held by you shall be accelerated so that all such
options shall be immediately exercisable.
 
  If your employment is terminated by the Company or its successor at any time
within one year from the date of a "change of control" event, you shall be
entitled to a severance amount equal to six (6) times your monthly base salary
in effect at the time of such termination (less applicable withholding taxes
and FICA).
 
  3.4 This Agreement shall be binding upon and inure to the benefit of both
parties and their respective successors and assigns, including any corporation
with which or into which the Company may be merged or which may succeed to its
assets or business.
 
  3.5 The captions of the sections of this Agreement are for convenience of
reference only and in no way define, limit or affect the scope or substance of
any section of this Agreement.
 
  3.6 In case any provision of this Agreement shall be invalid, illegal or
otherwise unenforceable, the validity, legality and enforceability of the
remaining provisions shall in no way be affected or impaired thereby.
 
  IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year set forth above.
 
                                          ASECO CORPORATION
 
 
                                          By: _________________________________
                                                    President and CEO
 
                                          EMPLOYEE
 
 
                                          By: _________________________________
                                                    Phillip J. Villari
 
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