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A Virtual Wafer-based Scheduling Method for Dual-arm Cluster Tools with Chamber Cleaning Requirements

Cluster tools play a significant role in the entire process of wafer fabrication. Wafer residency time constraints and chamber cleaning requirements are commonly seen in etching, chemical vapor deposition, coating processes, etc. They make the scheduling problem of cluster tools more challenging. This work aims to provide a solution for dual-arm cluster tools with wafer residency time constraints and chamber cleaning requirements. To do so, it proposes a novel virtual wafer-based scheduling method. By this method, under a steady state, a process module (PM) processes either a real or virtual wafer at a time. When a PM processes a virtual one, its chamber performs a cleaning operation. In this way, we can meet not only the strict residency time constraints for real wafers, but also innovatively performs chamber cleaning operations as required. Based on such a novel scheduling method, an efficient binary integer programming model is established to maximize the throughput of cluster tools. Finally, experiments are performed to show the efficiency and effectiveness of the proposed method.