Comparative factory analysis of standard FOUP capacities

Wafers in a 300-mm semiconductor fabrication facility are transported throughout the factory in carriers called front opening unified pods (FOUPs). Two standard capacities of FOUPs are 25 and 13 wafers. This paper describes a simulation study designed to compare the performance of a factory employing different FOUP capacities. The main performance measure considered is work-in-process (WIP) and the resulting cycle time. Batching policy, order arrival rate, average order size, the automated material handling system (AMHS) and the number of batch tools largely effect the performance of the models. Most of the empirical results show that the 25-wafer FOUP capacity provides a lower WIP level in a moderately loaded semiconductor factory.