To: DTselentis who wrote (21436 ) 3/24/1999 5:08:00 PM From: TechHunter Respond to of 25960
New Cymer Patent today....companysleuth.com PATENT No: 5887014 ISSUE DATE: Mar-23-1999 Process for selecting operating range for narrow band excimer laser ASSIGNEE: Cymer, Inc. San Diego, CA INVENTOR: Das; Palash P. Vista, CA OTHER DETAILS: Legal Rep: Ross, Esq.; John R. Application Date: Aug-20-1997 Application Number: 915030 Primary Examiner: Bovernick; Rodney ABSTRACT: A process for selecting an operating range for a narrow band KrF or ArF excimer laser. The laser is operated at a desired pulse energy until the fluorine concentration has depleted sufficiently so that the charging voltage needed for the desired pulse energy is at or near a predetermined maximum range. The average charging voltage, the average line width, and the average energy sigma are recorded; and the fluorine concentration is estimated or determined. A quantity of fluorine, at least sufficient to cause a measurable decrease in the charging voltage needed to produce the desired pulse energy, is injected; and another set of data is recorded. Another similar quantity of fluorine is injected, and another set of data is recorded. These two steps are repeated until the voltage is at or near a predetermined minimum voltage range. The recorded data are used to select an optional operating range. The data may be plotted to make the selection easier. The selection criteria may be determined based on the needs of the laser user. Normally the selection process will involve an intelligent compromise in which minimum values of charging voltage, fluorine concentration, line width and energy sigma are desired. For most uses, the optimal operating range will be a voltage range of 20% of the total possible voltage range and not close to either the minimum operating range or the maximum operating range.