A dynamic WIP control strategy for bottlenecks in a wafer fabrication system

摘要

The performance of a wafer fabrication system is constrained by its bottlenecks, which are difficult to detect and improve due to the complexity within the system. To weaken the negative effects of bottlenecks, a work in process (WIP) strategy is proposed in this paper which focuses on offline target WIP level setting and online WIP control simultaneously. First, bottlenecks are detected and classified based on the constraint weights which are decided by the sensitivity of the system performance to the machine's fluctuant availability. Second, the target WIP level is allocated to the bottlenecks to avoid the process fluctuation caused by unpredictable events. Third, in real time scheduling, the upstream machine of the bottlenecks modifies its dispatching order to adjust the deviation of the WIP levels at the bottlenecks. Finally, a simulation platform is developed to validate the effectiveness of the proposed method.