Long-term tool elimination planning for a wafer fab

Wafer manufacturers must make decisions regarding tool elimination due to changes caused by demand, product mixes, and overseas fab capacity expansion. Such a problem is raised by leading semiconductor manufacturers in Taiwan. This paper is aimed at developing a sound mechanism for tool portfolio elimination based on determining which equipment can be pruned. In the proposed mechanism, product mix, wafer output, capital expenditure, tool utilization, protective capacity, and cycle time are taken into the overall evaluation. This paper develops an integer programming model to avoid trial-and-error and to obtain the optimal solution. Compared to the current industry approach, the results show that the proposed mechanism can effectively identify the correct tools for elimination with a large capital savings and little cycle time impact.