The inclusion of future arrivals and downstream setups into wafer fabrication batch processing decisions

This paper presents a new batch machine dispatching policy that incorporates knowledge about future arrivals and the status of critical machines in subsequent (downstream) processing into the batch processing decision process. The intent is to create a methodology that balances the time lots spend waiting at a batch machine with the time spent in setup, thus improving the overall cycle time. Using discrete-event simulation, this heuristic is compared to existing heuristics that do not consider downstream operations to evaluate their impact on the cycle time both for a small three-machine system and a semiconductor manufacturing facility model. The results showed considerable improvement in cycle times for the small three-machine system. Results for the semiconductor-manufacturing model with downstream batching indicate that the new heuristic is robust but produces results consistent with the current standard heuristic; however, with further modifications, this heuristic may be capable of producing significantly better results.