A comparison of control methods for production areas with time constraints and tool interruptions in semiconductor manufacturing

This paper investigates and compares different control mechanisms for timelink areas in a semiconductor manufacturing line with tool downs. Timelinks are time constraints between consecutive process steps. The goal of this paper is to search for good and practicable control mechanisms, that determine optimal release dates for lots in front of a timelink area with a minimum of time constraint violations. To evaluate good control mechanisms, this paper will investigate risk factors which are based especially on failure probability of tools, with the aid of survival analysis, at the end of a timelink area. These risk factors will be included in a mixed integer program (MIP) together with the time constraints. To test the developed scheduling method the MIP will be simulated in a hybrid model (symbioses of simulation and a mathematical solver) under the aspect of rolling horizon planning with a simulation of unscheduled tool downs. On the basis of the failure probability there will be also different capacity calculations to derive and compare dispatching rules. The dispatching rules are tested by a discrete simulation model that considers also unscheduled tool downs. At last the results of the MIP are compared with the prepared dispatching rules.