Simulation based real-time scheduling method for dispatching and rework control of semiconductor manufacturing system

Implementing effective and efficient scheduling methods is a critical means to gain competitiveness for wafer fabrication manufacturers in today´s global semiconductor market. Qualified scheduling approaches should make adaptive decisions based on real-time processing status. Most of real-time scheduling algorithms are open-loop ones, they do not continuously monitor the performance of the semiconductor manufacturing system (SMS) and select the optimal rule or strategy to improve performance. We develop a simulation based real-time scheduling (SBRS) mechanism in which dispatching rules and rework strategies vary dynamically based on real-time information. This paper also presents a real-time integrated scheduling (RIS) algorithm, which combines different dispatching rules and rework strategies. A case study is described to examine the performance impact of the scheduling method measured by cycle time, work in process, on-time delivery, and throughput. The results of the computational experiments show that the proposed scheduling method is superior to the use of static scheduling methods.