Weighted grey relational analysis to evaluate multilevel dispatching rules in wafer fabrication

What is it about?

Wafer fabrication is complicated due to a high number of product mix and re-entrant process steps. Scheduling decisions are essential to control the operational performance of wafer fabrication effectively. This research proposes weighted grey relational analysis (WGRA) method to evaluate the performance of 325 multilevel dispatching rules in the batched wet clean process. Performance measures include cycle time, move, tool idling, and queue time. The research methodology involves multilevel dispatching rule generation, simulations, WGRA, and result analysis. The simulation model and data are obtained from a wafer fab in Malaysia. Two seasons varying in customer orders are defined. To benchmark performance and investigate the effect of varying values of coefficient, the models are compared against TOPSIS and VIKOR. Results show that the seasons prefer different multilevel dispatching rules. Compared to VIKOR and TOPSIS, WGRA generates more stable rankings in this study. The application illustrates the effectiveness and practicality of the WGRA model in analyzing multilevel dispatching rules.

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