Improving the performance of dispatching rules in semiconductor manufacturing by iterative simulation

In this paper, we consider semiconductor manufacturing processes that can be characterized by a diverse product mix, heterogeneous parallel machines, sequence-dependent setup times, a mix of different process types, i.e. single-wafer vs. batch processes, and reentrant process flows. We use dispatching rules that require the estimation of waiting times of the jobs. Based on the lead time iteration concept of Vepsalainen and Morton (1988), we obtain good waiting time estimates by using exponential smoothing techniques. We describe a database-driven architecture that allows for an efficient implementation of the suggested approach. We present results of computational experiments for reference models of semiconductor wafer fabrication facilities. The results demonstrate that the suggested approach leads to high quality solutions.