Capacity planning with capability for multiple semiconductor manufacturing fabs

A capacity planning system (CPS) that considers the capacity and capability of equipment is developed for multiple semiconductor manufacturing fabs. On the basis of pull philosophy and the assumption of infinite equipment capacity, the system determines each lot's release time, start fab, and the capability of the equipment. CPS includes three main modules-the WIP-Pulling Module (WPM), the Workload Accumulation Module (WAM) and the Wafer Release Module (WRM). WPM pulls WIP from the end of the process route to meet the master production schedule (MPS). WAM then calculates the expected equipment loading in different time buckets. If WIP cannot meet the MPS requirement, then for each lot to be released, WRM evaluates the expected loading of many fabs, based on the lot's planned start time, and then determines the lot release time, the start fab and the equipment capability, to optimize the workload balance among all fabs. Simulation results indicate the effectiveness and efficiency of this system. A CPS that combines Adjusted Release Time (ART) and Path Load performs best in terms of three performance measures. This finding shows that CPS based on the combination of ART and Path Load can efficiently balance the equipment workload among the various fabs, on various days, and across various equipment at various levels of demands.