A Study On Wafer Fabrication On-time Delivery Improvement

Semiconductor wafer fabrication system is currently one of the most complex manufacturing systems in the world. Due to its own characteristics:large number of products、the production cycle time is very long、can be returned、equipment maintenance uncertainty, there is a large difference with the traditional mode of production. Because the semiconductor wafer fabrication is one of the high-investment, high-margin, high-risk and most intense competition in industry, semiconductor wafer manufacturing line modeling and optimization become the focus of the study by academic and engineering in recent years, which has profound theoretical significance and wide application prospect.Based on the 6 inches semiconductor wafer fabrication system and combined with B company specific project case. Firstly, we research the bottleneck capacity and the production cycle time, which affect the on-time delivery rate directly. Secondly, through setting up the Fab capacity calculation model, we identify the bottleneck resources and non-bottleneck resources in the production line. And then, we combine with the decomposition method which commonly used in large and complex systems, and take constraint management (TOC) together with other theories to carry out the equipment capacity improvement and the overall efficiency improvement continuously in the bottleneck resources. In addition, we maximize the bottlenecks throughput by selecting the optimization strategy in lots scheduling. For the non-bottleneck resources, we use the lots scheduling optimization strategy to effectively reduce the lots average waiting time in progress and increase the WIP transfer ratio from bottleneck resources to non-bottleneck resources, by adjusting the WIP distribution to indirectly improve the bottleneck capacity. Finally, based on the Fab capacity utilization fixedness, the production cycle time reduced both in the bottleneck resources and the non-bottleneck resources with low cost, which also achieved the on-time delivery rate which the Fab key performance index improvement.