Finite-capacity production planning algorithms for a semiconductor wafer fabrication facility

We consider the problem of production planning for a semiconductor wafer fabrication facility producing application-specific integrated circuits (ASICS) to customer order. Using a simple planning algorithm based on forward scheduling for WIP and backward scheduling for new orders, the effects of the level of detail at which the production process is modelled was examined. A simulation study showed that considering all near-constraint workcentres explicitly as having finite-capacity gives the best results. Also examined were the effects of undercapacity planning, and it was shown that when coupled with a shop-floor scheduling procedure driven by the planned completion date rather than customer due dates, significant improvements in both delivery performance and system predictability were obtained.