Qualification management to reduce workload variability in semiconductor manufacturing

Variability is an inherent component of all production systems. To prevent variability propagation through the whole production line, variability must be constantly monitored, especially for bottleneck toolsets. In this paper, we propose measures to evaluate workload variability for a toolset configuration. Using industrial data, we show how making the toolset configuration more flexible by qualifying products on machines decreases variability. By quantifying the toolset workload variability, our variability measures makes it possible to estimate the variability reduction associated to each new qualification. The industrial results show significant workload variability reduction and capacity improvement.