Optimal Cyclic Scheduling of Wafer-Residency-Time-Constrained Dual-Arm Cluster Tools by Configuring Processing Modules and Adjusting Robot Waiting Time

Optimal cyclic scheduling problems of wafer-residency-time-constrained (WRTC) dual-arm cluster tools (CTs) in semiconductor manufacturing remain open. Compared with existing methods that use all processing modules (PMs) to process wafers, we adopt a new approach that adjusts both PM count and robot waiting time to adjust the wafer processing cycle time of each wafer processing step. Based on it, we derive necessary and sufficient conditions for schedulability of WRTC dual-arm CTs, which are less conservative than previous ones. We then present an algorithm with which an optimal cyclic schedule can be efficiently realized. Examples are given to show the superiority of the developed method over existing ones.