Modeling the variance of the durations of maintenance activities in semiconductor fabs

The reduction of equipment variability of availability can significantly reduce cycle times, improve yields, reduce time-to-market and lower overall operational costs. Despite extensive efforts to reduce variability of availability, however, the execution of preventive maintenance (PM) is still one of the main sources of equipment variability of availability in the industry. In this paper, a model for PM duration variance is proposed. The model is based on the parts of the PM and the standard PM flow, and it provides a framework for modeling and segmenting the PM duration variance in the semiconductor industry while highlighting inefficiencies and improvement opportunities.