An analysis of tool capabilities in the photolithography area of an asic fab

Photolithography is generally regarded as the most constraining element in semiconductor manufacturing. This is primarily attributable to the high capital investment and extensive re-entrant flows throughout this section. Cycle time management in this area is crucial to balance the trade off between tool utilization and cycle time. In a low volume, high product mix fab the inclusion of tool capabilities, and their status, can significantly affect tool utilization and overall cycle times. In this paper a simulation model is developed to aid cycle time decision making policies in the photolithography section of a low volume, high product mix fab. The objective of the study is to determine the optimum course of action, for varying levels of expected increased demand, while maintaining acceptable cycle times and minimizing total capital spent in photolithography. The actions reviewed include the increased use of capabilities where available, followed by the purchase of new photolithography equipment.