New Particle Monitoring Strategies in UPW for 300 mm Fabs
Process failures caused by particles in Ultra Pure Water (UPW) are relatively infrequent events, but with the move to 300 mm wafers and 90 nm line widths, they can have significant financial impact. Most particle monitoring strategies in the past focused on the use of the mobile and inline high sensitivity 0.05 micron particle counters. This paper examines the opportunities to improve performance, track data trends, and reduce cost by using a combination of both high sensitivity particle counters (to 0.03 microns) and less expensive lower sensitivity (0.1 microns) counters with very high sample volumes. The scope of this paper details the impact of size sensitivity, sample volume, and zero count level on particle counter performance. Practical monitoring considerations and particle distribution differences between poorly filtered and highly filtered systems are discussed.