EXHIBIT 10.31

                                                                      One of two

July 29, 1999

Ms. Kazuyo N. Heinink
9863 E. Gelding Drive
Scottsdale, AZ 85260

Dear Kazi,

It is my pleasure to offer you the position of Vice  President of Marketing  for
Semitool, Inc. reporting to me. The terms of this offer are as follows:

         1.       Your start date will be as soon as possible, but no later than
                  August 23, 1999.

         2.       Your base salary will be $150k per year, paid semi-monthly.

         3.       Considering specific goals and objectives we jointly compose,
                  you will be able to earn up to 30% of your base salary as a
                  bonus.

         4.       The company will provide company housing or a $1000.00 a month
                  housing  allowance  for  the  first  six  months  you  are  in
                  Kalispell.   After  this  period,   we  will   determine   the
                  appropriate  location for this  position.  If it requires that
                  you move,  Semitool will assist in the move of your  household
                  goods by providing a company  sponsored move, this item not to
                  exceed $15,000.00.

                  During the first six months, you will be afforded one trip per
                  month to Phoenix when it can be combined  with other  Semitool
                  business, booking in advance for the best possible rates.

                  The company  will provide a company car or leased car for your
                  use in  Kalispell,  and at the end of the first  six  months a
                  decision  will be made  regarding a company car,  based on the
                  location of the position.

         5.       As part of your  incentive  package  you will  receive  40,000
                  stock options.  Following Board approval,  they will be issued
                  and vested according to the current distribution plan. The
                  value of the stock option will be set the day it is
                  distributed.

         6.       You will be entitled to three weeks vacation  within the first
                  year  of  employment,   with  scheduling  subject  to  company
                  approval,  until you reach  ten years of  employment  when you
                  will be eligible for four weeks.

         7.       You will be  entitled  to all  standard  benefits  offered  to
                  Semitool employees,  some of which have waiting periods.  They
                  include life,  medical and dental  insurance  (eligibility the
                  first of the month following employment).

                  You will be eligible  for the 401(k)  Profit  Sharing  plan on
                  October 1, 1999.  However,  if you have funds  currently  in a
                  qualified  plan,  you may  roll  those  funds  over  into  the
                  Semitool 401(k) Plan prior to that date.

         8.       As a condition of your employment you will be required to sign
                  a Confidentiality/conflict of interest agreement.


<PAGE>


                                                                      Two of two
                                                                      K. Heinink

         9.       None of the above terms of this offer represents an agreement
                  by you or Semitool, Inc. for any specific length of
                  employment.  Either you or Semitool may, at any time,
                  terminate the employment relationship upon notice to the other
                  party. As with all Semitool employment positions, there is a
                  90 day probationary period.

                  Any  controversy  or  claim  arising  out  of  termination  of
                  employment after your probationary period has expired shall be
                  settled  by  arbitration  as  provided  in  Montana's  Uniform
                  Arbitration Act, 27-5-211 et seq., MCA.
                  The laws of Montana shall apply.

         10.      In the unlikely event you or Semitool  determines this working
                  relationship  is not to continue,  we will provide a six month
                  severance  package  to defray  the cost of your  finding a new
                  position.


Sincerely,                                Acceptance: I have read and understand
                                          all of the above and accept the terms
SEMITOOL, INC.                            of employment with Semitool, Inc.

                                          /s/Kazuyo N. Heinink
                                          --------------------------------------
                                          Kazuyo N. Heinink
Fabio Gualandris
President                                 Date  7/31/99
                                               ---------------------------------

/s/Fabio Gualandris
----------------------------