Abstract
Semiconductor industry is capital-intensive industry. Due to increasing demand, many semiconductor companies raise their capacity substantially. How to reduce manufacturing cost becomes an important issue. The yield of wafer influences manufacturing cost directly. The use of control wafer is to control the wafer quality. For wafer manufacturing process, control wafer are used to maintain the quality of production wafer and monitor the environment of production equipments. Control wafers are not regular wafers for sale, but they are indispensable for wafers fabrication.Lack of control wafers will stop production line. In order to avoid this problem, most wafer factories keep a large number of control wafers inventory. A large number of control wafers imply a huge amount of inventory costs. Considering control wafer usage and downgrade rule, this study develop a control wafers production planning system to schedule the usage of control wafers under the assumption that control wafer can not be short.This study develops a linear programming model, based on the demand of manufacturing operation. By using this formulation, hopefully we can quickly obtain a plan, which minimize the usage of new control wafer.