An optimal OHT dispatching system for 300 mm semiconductor manufacturing

This paper presents the development of an optimization-based system for OHT (overhead hoist transport) dispatching with blocking effects in 300 mm semiconductor manufacturing. The OHT dispatching problem is first formulated into an integer programming problem with OHT dynamics and location constraints. We adopt the linear programming solver, UNDO, to develop the optimal OHT dispatching system. Numerical results demonstrate that this approach performs well in minimizing the total completion time of transport jobs while minimizing the traveling times of empty but dispatched vehicles. It takes about 6.5 seconds to solve the problems of realistic scale. The developed optimal OHT dispatching system is effective and applicable in practice.