Optimal wet-furnace machine allocation for daily fab production

This paper presents the design of an efficient and near-optimal machine allocation method for wet bench and furnace machine groups to achieve daily production targets and high moves. The core of the method consists of an innovative integer linear programming problem formulation of the complex operation constraints such as variable size batching, queue time, cross fab transportation and linearization of the objective function, and the skillful application of an optimization tool suite. Test results over real fab data clearly demonstrated the superiority of the method than a currently practiced heuristic in bottleneck (furnace) machine utilization (potentially by 10-15%) and it leads to nearly 50% reduction in average total waiting time per FOUP. Its computation efficiency (in seconds) indicates a strong potential for both solving larger sized problems and extensions to dynamic allocations.