Empirical Relationship between Cycle time Impact and Batching on Furnaces in Semiconductor Foundry

Semiconductor manufacturing (fab) is a highly complex, cost intensive and competitive industry. For a fab, batch factor for furnace tools is a key fab performance metric for capacity and cycle time assessment. Batch production is one of the manufacturing methods where, a group of wafers can be processed together in a batch in a given timeframe. Furnace tools have the ability to batch the wafers together. In this paper, we propose to establish the relationship between batch factor and cycle time to calculate the optimal batch factor within the permissible limits of cycle time. Most furnace tools need to wait for the same kind of wafers to improve its batch factor. Thus, to achieve large batch factor, the cycle time of the WIP at these furnace tools inadvertently becomes high. This creates a need to know how high batch factor can increase without adversely affecting the cycle time and help in making optimized batching decisions.