Borderless Fab Scenarios in Hierarchical Planning Settings: A Simulation Study

Lots are transferred in borderless fab (BF) scenarios from one wafer fab to another nearby fab to carry out process steps of the transferred lots. BF aims to compensate for scarce bottleneck capacity in some of the wafer fabs. One goal of the master planning function is to distribute the demand over the wafer fabs such that situations are avoided where large queues of lots arise in the wafer fabs. Due to inaccurate modeling of capacities and lead times in master planning, this goal is not always reached. Wafer fabs are often heretogenous. This leads to additional costs for BF scenarios which might make them less attractive. We are interested in exploring conditions with respect to master planning and wafer fab heterogeneity under which BF scenarios are still beneficial. Master planning, production planning, and the BF lot transfers are carried out in a rolling horizon setting using a cloud-based infrastructure.