Abstract
In semiconductor manufacturing, critical layers of a wafer lot often required to be processed at the same photolithographic machine in order to meet stringent cross-layer registration requirement. Non-critical layers do not have such requirement.In this thesis, an algorithm was developed to balance the machine loading for photolithographic area considering the mixture of critical vs. non-critical layers constraints, the re-entrant nature in a fab, and the individual machine break down probabilities. The algorithm assigns the machines for critical layers based on the loading for the machines with respect to the critical layer’s remaining life-cycle loading and assigns the machine’s for non-critical layers based on relative dynamic loading of the available machines.Simulation results indicated better overall local balance, throughput, and in fab cycle time of this approach compare to random machine assignments and intuitive dynamic loads balancing approach. The research continued to test various common order releasing and dispatching combinations. Best machine combinations of order releasing and dispatching methods were identified.