Optimizing multichamber work cell management: an application to a DRAM wafer fab

The management of a work cell consisting of multichamber systems Endura 5500 PVD is addressed with the goals of maximizing production volume and facilitating maintenance plans. These objectives are pursued through suitable system configuration and loading. A mixed integer linear programming model incorporating such requirements as workload equalization and fault tolerance is devised to find optimal chamber assembly. The nominal productivity under distinct feasible production modes is evaluated by simulating Endura operation scheduling, and then utilized as problem input to compute nominal work cell productivity under steady-state inventory conditions. This method has been successfully adopted in an actual wafer fab to determine sputtering capacity allocation.