Systems of multiple cluster tools: configuration and performanceunder perfect reliability

摘要

By extrapolating technological trends, one can expect future fabsnto consist largely of highly reliable cluster tools. Such trends raisenthe issues of how cluster tools should be configured (i.e., how modulesnshould be grouped together), and the impact of configuration on optimalnlot size. This paper generates equation-based models to compare thenthroughput and cycle time of different systems that perform the samensequence of process steps, with the same total number of modules groupednin different ways into multiple cluster tools. The two extremes of thenspectrum of possible cluster tool configurations are considered: thenserial configuration, in which a wafer visits each module in the clusterntool, and the parallel configuration, in which all of the modules in thencluster tool are identical. The models predict the following for typicalncluster tool parameters and process times. When all process step timesnare identical, systems of serial-configured tools can achieve the samenthroughputs with lower cycle times, as their parallel-configuredncounterparts. However, if process times in the sequence significantlyndiffer from one another, then systems of parallel-configured tools maynachieve lower cycle times than their serial-configured counterparts atnhigh throughputs. Finally, the serial configuration significantlynreduces the lot size required to achieve total throughput capacity