Methodology to evaluate the impact of AMHS design characteristics on operational fab performance

Today's 300mm semiconductor facilities rely almost completely on Automated Material Handling Systems (AMHS) to transport wafers to equipment and storage areas in the wafer fabrication plant (fab). As the cost of equipment increases and the process technology becomes more and more sensitive to delivery times between steps, AMHS performance has become increasingly important to overall factory performance. Current AMHS design methods focus primarily on optimizing the balance between AMHS cost and AMHS performance. Understanding the influence of AMHS performance on fab operations has become an area of focus during the design process. This paper proposes a methodology to correlate AMHS performance measurements with simulated fab performance measures using a linked AMHS-fab model. This methodology facilitates model setup, scenario modification, model linkage, and calculations of performance impact. A sample evaluation study demonstrates the validation and analysis process, and derives conclusions applicable during the AMHS design process.