Modeling staffing requirements within a semiconductor manufacturing environment

In this paper we demonstrate the use of an analytical queuing model and a simulation model for calculating the minimum staffing level in a semiconductor manufacturing environment. The analytical model analyzes the number of operators required to process wafers and perform operator-level equipment service and maintenance. Machine interference is modeled as an M/M/c queue with finite calling population. When compared to a simulation model, the analytical model yields close results in various factory loading and equipment maintenance plans. The analytical model is then implemented as an Intranet on line tool for staffing analysis in a Motorola factory. The implemented system allows fast and accurate analysis on different equipment groupings (assignments of equipment to bays), PM schedule, product mix, and operator loading assumptions.