Intuitive dispatching method to handle the 450 mm wafer and prioritize jobs in a conveyor of semiconductor industry

Abstract

An effective material handling system can help factories meet the transportation demands for new wafer size since the size increases from 300 mm to 450 mm. With advantages proved, conveyor-based automated materials handling system (AMHS) is chosen as the next generation transport system. However, this transport system also faces with the problems about traffic jams when having so much lot in loop and loading or unloading procedures. Besides, a higher priority lots should enjoy greater transportation privileges than those with a lower priority. Thus, one good dispatching rule is very helpful for an AMHS. This research proposes restructuring loop configurations for conveyor-based AMHS and develops an effective dispatching rule, named rota-caster in heuristic preemptive dispatching method (R-HPD). Simulation results demonstrate that the R-HDP can provide better performances than the best existed method (DPD). The R-HPD rule reduces the average delivery time by 49.4% for hot lots and 50.5% for normal lots. Moreover, the average delivery time of normal lot is not affected so much when bay loading and hot lot ratio increase.