Selection of dispatching rules on multiple dispatching decision points in real-time scheduling of a semiconductor wafer fabrication system

Abstract

Semiconductor wafer fabrication involves one of the most complex manufacturing processes ever used. To control such complex systems, it is a challenge to determine appropriate dispatching strategies under various system conditions. Dispatching strategies are classified into two categories: a vehicle-initiated dispatching policy and a machine-initiated dispatching policy. Both policies are important to improve the system performance, especially for the real time control of the system. However, there has been little research focusing on combining them under various situations for the semiconductor manufacturing system. In addition, it is shown that no single dispatching strategy consistently dominates others in all situations. Therefore, the goal of this study is to develop a scheduler for selection of dispatching rules for dispatching decision variables in order to obtain the desired performance measures given by a user for each production interval. For the proposed methodology, simulation and competitive neural network approaches are used. The results of the study indicate that applying our methodology to obtaining a dispatching strategy is an effective method considering the complexity of semiconductor wafer fabrication systems.