Manufacturing schedule of dual-armed cluster tools based on heuristic search

Cluster tools are fundamental equipments in over-8-inch wafer manufacturing. Due to the toolspsila unique physical structure and particular semiconductor manufacturing demands, the scheduling of cluster tools is more complex than normal Job-Shop problems. This paper proposes a scheduling algorithm for dual-armed cluster tools based on Heuristic Search. We mainly examine the scheduling technique under the most complex situation including residency constraints and multi-visit requirements. A periodic idea that every wafer enters into cluster tools in the same interval is proved still feasible under this situation. To find a conflict-free schedule under a fundamental period (FP) in short time, we define an evaluation function to select the most proper operation sequence from all the possibilities, and some feedback information from a conflict is used to prevent over pruning. Experiments under the most complex situations demonstrate the feasibility and effectiveness of this algorithm. Other experiments with looser constraints show its expansibility and adaptability.