A modular production planning system for semiconductor manufacturing

This dissertation presents an optimization-based global production planning system, the Berkeley Planning System (BPS), for the semiconductor merchant industry. BPS is a result of the effort by a research group under the direction of Professor R. C. Leachman within the U.C. Berkeley Engineering Systems Research Center. The objective of the research is to develop and demonstrate a unique, integrated planning system which can significantly help improve customer service (specifically, on-time delivery) and resource productivity in the semiconductor industry.; BPS makes extensive use of Operations Research models to cope with the complexities of the planning problem in this industry. It is a modular planning software specifically designed to automatically generate capacity-feasible start and out schedules for all manufacturing areas, considering the peculiar product and production process structures of semiconductor manufacturing, and an availability schedule for use in quotation to customers of delivery dates.; Linear programming formulations are developed that incorporate dynamic production functions modeling the input-output relationships of semiconductor manufacturing processes. These functions allow one to represent complex capacity usage in a computationally tractable manner. Linear programming formulations are also developed to optimize the translation of demands for each marketed item into production requirements for the various manufacturing versions of the item, and to optimize the allocation of bin-distributed output among customer specifications. The objective functions of these linear programs maximize discounted cash flow and cash flow proxies for customer service. Multiple priority demand classes are defined. Customer service in higher priority classes constrains the scheduling of lower class demands, reflecting good customer service and management of forecasting uncertainties.; BPS consists of five calculation modules designed to decompose the overall production planning calculation for a semiconductor manufacturer into tractable pieces. The BPS software includes more than 50,000 lines of code. As of this writing, the BPS software is in regular use at one of the top ten merchant semiconductor firms in the United States, preparing production plans weekly for about 10,000 end products over a 1.5-year horizon. Compared to MRP (Manufacturing Resources Planning) systems, BPS is a major improvement in planning technology.