Daily scheduling for R&D semiconductor fabrication

The daily scheduling for a research and development (R&D) pilot line of semiconductor wafer fabrication is addressed. An integer programming problem formulation is given, which captures the salient features, such as high variety and very low volume, cyclic process flows, batching at diffusion machines, single mask for each photolithography operation, loop test, and engineering splitting and merging of wafer lots. A solution methodology for scheduling flow shops based on Lagrangian relaxation is extended to solve this class of problems. It may also effectively handle data inaccuracy and cope with production uncertainties. Numerical results demonstrate both the feasibility and potential of this method