A multi-stage fluctuation smoothing method for multiple bottlenecks in wafer fabrication

Abstract

The performance of a wafer fabrication system is constrained by its bottlenecks, which is often affected by the system fluctuations and unpredicted events, e.g., machine breakdown. Considering the re-entrant process flow in wafer fabrication, we propose a scheduling method that divides the process flow into several stages and protects the bottleneck step at each re-entrant stage from the system fluctuations. Furthermore, due to the multiple bottlenecks in wafer fabrication system, we identify the bottlenecks by sensitivity analysis on machines' capacity. Then, during the real-time scheduling, the bottlenecks with stronger constraints are assigned with higher priority than the bottlenecks with weaker constraints. Finally, a set of simulation experiments are performed to validate the effectiveness of the proposed method. © 2013 Springer-Verlag London.