Capturing Tool Availability in the Capacity Model based on Actual Utilization

Abstract

For a semiconductor wafer fabrication factory, availability of equipment is a key fab performance metric for the periodic assessment of fab capacity. The current capacity model assumes an average of weekly actual availability for the equipment groups to evaluate the throughput of the equipment group for a given timeframe. This does not capture the cases of equipment groups that will have degradation in availability as they see more Work in Progress (WIP) coming through. This study proposes a new mathematical model to determine the availability of the equipment groups to be used in the capacity model based on the actual in-line utilization of the equipment group.