Schedulability analysis for dual-armed cluster tools with mixed-processing of multi-variety wafers

Wafer fabrication tends to small batch, and single wafer processing is effective in cluster tools. With the decrease of processes, redundant processing modules are adopted to improve the utilization of cluster tools. The scheduling of mixed-processing of multi-variety wafers should be developed for dual-armed cluster tools. Based on resource oriented Petri net model, we analyze the process by the traditional swap strategy, then wafer processing cycle time and robot cycle time are obtained. A theorem of the schedulability is achieved by analyzing the processing parameters of multi-variety wafers. The schedule is obtained by a scheduling determining programming. Finally, illustrative examples are presented to show the usage of the programming.