Impact of Sampling on W@R and Metrology Time delay
Résumé
The metrology is a very important step in the semiconductor manufacturing process. A 100% inspection rate is ideal to ensure high quality of product and good performances of production tools. However, this causes an increase in the size of the metrology machines' queues, and then, a process slowdown. In addition, the high cost of meteorology machines prevents the possibility of their multiplication. This paper studies the impact of the reduction of the inspection rate on performances of production system. The evolution of the Wafer at Risk (W@R) measure is used as a performance indicator of the sampling strategy. The metrology delay time is also considered in order to evaluate the risk exposure of the process tools.