Single-wafer cluster tool performance: an analysis of the effects of redundant chambers and revisitation sequences on throughput

Recent trends in the semiconductor industry indicate the need to explore alternatives to batch-wafer manufacturing. One proposed alternative is a micro-factory based on cluster tools. This paper presents an analysis of the effect of redundant chambers and chamber revisitation process sequences on the throughput in an individual cluster tool. Theoretical models which quantify the time required to process a lot of wafers in a cluster tool are developed for these situations. The differences between scheduling algorithms which use the load-lock as a queue and those that do not are also explored. Finally, the models developed in the work are integrated into a model which bounds the minimum theoretical turn-around-time which can be achieved in a cluster based fab.