Simple performance models for integrated processing tools

Integrated processing tools are becoming increasingly prevalent in modern fabs. Integrated tools consist of several process modules connected around a central handler such that the modules can process several wafers from the same lot simultaneously. Lithography cells and vacuum cluster tools are examples of integrated processors. Simple, intuitive models of the cycle time, throughput, and wafer cost of integrated tools are introduced. The models use two measurable parameters that aggregate tool operations: the incremental cycle time is the average increase in cycle time resulting from a lot size increment of one wafer and the fixed cycle time is the portion of cycle time that is independent of lot size. One example shows how an empirical analysis of a commercial CVD cluster tool was used with the models to identify opportunities to increase tool throughput. In a second example, analytical models of the incremental and fixed cycle times are used to provide insight into the effects of tool configuration on performance. Finally, simulations of single integrated tools are used to show some limitations of the model.