A Spatio-Temporal Conflict Elimination Search Algorithm for Automated Material Handling Systems in Semiconductor Fabs

Automated material handling system (AMHS) ensures efficient transport of material from one place to another in the manufacturing area, which is widely adopted to transport wafers in semiconductor manufacturing facilities. Efficient transportation in AMHS is crucial for maintaining manufacturing chain continuity, preventing machine idle time, and reducing cycle times by minimizing waiting time between operations. In this paper, we propose a spatio-temporal conflict elimination search (STCS) algorithm to improve the transportation efficiency of AMHS, which incorporates a job dispatching strategy based on global vehicle movement and idle vehicle management based on a triggered move least policy. Besides, STCS resolves the collisions of vehicles at merge nodes by a spatio-temporal elimination method. Simulation experiments on real-world fab data show that the STCS algorithm achieves competitive performance regarding to the production efficiency and vehicle utilization. Some key features are analyzed to identify the intrinsic properties of AMHS, which encourages decision-makers to adopt proper configuration in different manners to reduce costs and improve efficiency.