Simulation-based optimiziation to design equipment health-aware dispatching rules

In this paper, we discuss the construction of dispatching rules for semiconductor wafer fabrication facilities (wafer fabs) that take equipment health issues into account. Monitoring the equipment health status of critical machines is important to maintain process quality and to reduce rework and scrap. Usually, there is a tradeoff between quality- and productivity-related goals in wafer fabs. Obtaining an appropriate compromise between these two objectives is addressed by considering blended dispatching rules. Simulation-based optimization based on variable neighborhood search (VNS) using a reduced simulation model of a wafer fab is applied to determine appropriate weights for the different priority indices. We demonstrate by simulation experiments that the obtained blended dispatching rule performs well compared to dispatching rules that are designed only for a single quality- or productivity-related objective.