Scheduling MEMS manufacturing

This paper focuses on the production scheduling in MEMS (microelectromechanical system) manufacturing. The whole MEMS production process can be organized into three sub-processes, i.e., the wafer front-end process, the wafer cap process and the back-end process. Every wafer processed by the wafer front-end process needs to be bonded with a wafer that is manufactured in the wafer cap process, and then it will be sent to the back-end process. Therefore, the synchronization of the release of wafers into the front-end process as well as the wafer cap process becomes an important topic. Ineffective coordination will create a long cycle time and large WIP (work-in-process). Four synchronization rules are developed and they are evaluated together with two release rules and five dispatching rules. The performance measures considered are cycle time, throughput rate and WIP. A visual interactive simulation model is constructed to imitate the production line. The simulation results indicate that synchronization rules, release rules, and dispatching rules, have significant impacts on the performance of MEMS manufacturing and the best policy combination is Littlesyn-CONWIP-SRPT.