Modeling vehicle-free transport to enable elimination of bottlenecks

摘要

Automated material handling systems (AMHS) are critical to the infrastructure of a 300mm fab. Modern AMHS must support movement demands that dynamically range from 1000 FOUP moves/hr up to 10,000. Demand in a single bay can exceed 1000 moves/hour. Many fabs are now interested in reducing their lot size to reduce cycle time and inventory. If the current 300mm Prime Initiative effort aligns semiconductor manufacturers and equipment suppliers to enable production of single wafer lots, movement demand will increase 25-fold. AMHS should never be a bottleneck to fab output, therefore very high capacity AMHS is required to support 300mm Prime. Results of a comparison study of the capacity of various AMHS layouts and a strategy for eliminating bottlenecks are presented.