| Summary: | 碩士 === 國立交通大學 === 工業工程與管理系所 === 93 === In today’s versatile environment, semiconductor industry not only needs the flexible production advantage to expand the market by customization, but it also needs to decrease R&D time in advanced process or engineering lots by shortening production cycle time in the attempt to create future market. In order to shorten the production cycle time of specific products or engineering lots, a higher priority is often given to these lots in current wafer fabrication. To meet the importance of multiple-priority orders in the semiconductor industry, this research proposes a decision model in the aggregate production planning stage. The decision model simultaneously considers the positive and negative effects and future benefits of multiple-priority orders in the selection of the optimal priority mix.
The optimal priority mix decision model first develops analytic mechanism for setting upper-limit of higher priority orders. With such a limit, we set all the available priority mixes under the same throughput tartget. Then we use simulation model to obtain production performance foe each available priority mix based on the current capacity and the assumption that bottleneck cannot be shifted and hot lots are not restricted by batch size constraint. Next, a production performance assessment mechanism is developed to appraise the losses due to the reduction of production performance under each multiple-priority mix, and then each of the uncompetitive mixes is deleted. Next, an optimal priority mix selection mechanism first utilizes an immediate profit standardization module to generate a no-scale objective measure for each feasible priority mix based on its profit. Aslo an invisible benefit assessment module is developed based on analytical hierarchy process to produce a subjective measure for each feasible priority mix based on future benefit of each mix. Finally, the objective and subjective information is integrated so as to select the optimal priority mix which will lead to the maximum benefit for the entire system.
Experiment result shows that the proposed decision model supplies a complete planning and decision process for managers to select the optimal priority mix. This model not only has a comprehensive analysis on the financial impact by multiple-priority orders, but also considers the future benefit that higher-priority orders can offer under different priority mixes. Through the decision process, managers can get relevant and complete information to determine the optimal priority mix. The result can provide production system with reference for accepting and managing orders in the future.
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