EXHIBIT 10.12 August 11, 1998 Mr. Sebastian J. Sicari 63 Townsend Farms Road Boxford, Massachusetts 01921 RE: Stock Options - ----------------- Dear Sebastian: On behalf of the Compensation Committee of the Board of Directors of Aseco Corporation (the "Company") please accept this letter as confirmation that, notwithstanding the terms of the stock option agreements pursuant to which your options to purchase common stock of the Company were granted (Schedule A ---------- attached lists your stock options), in the event your employment with the Company is terminated for any reason except for cause (as defined in your severance agreement with the Company as of December 30, 1996), each of your options shall be exercisable at any time prior to the earlier of (i) the third anniversary of the date your employment with the Company terminates or (ii) the expiration date of the option. Sincerely yours, /s/ Dr. Sheldon Buckler - -------------------------------------- Dr. Sheldon Buckler Chairman of the Compensation Committee SCHEDULE A ---------- Grant Date Number of Shares Exercise Price Expiration Date - ---------- ---------------- -------------- --------------- 1/12/94 75,000 $ 5.375 01/12/2004 05/15/95 10,000 $13.00 05/15/2005 08/23/96 67,500 $10.375 08/23/96 10/18/96 22,500 $ 9.875 10/18/2006 05/10/97 25,000 $ 9.875 05/10/2007 08/11/98 60,000 $ 3.16 08/11/2008