An event graph based simulation and scheduling analysis of multi-cluster tools

Simulation methods are extensively used in modeling complex scheduling problems. However, traditional layout of simulation models can become complicated when they are used to find optimal scheduling in complex systems such as multi-cluster tools for semiconductor manufacturing. In this paper, we study a decision-moving-done method of event driven simulation for multi-cluster tools. Based on this method, we are able to manage all the activities in the simulation. The proposed event graph based simulation study can further be integrated into a pruning search algorithm to find the optimal robot scheduling sequence. Incorporated with simulation model, the search algorithm detects deadlocks and significantly reduces the computing time. A chemical-mechanical planarization (CMP) polisher is used as an example of the multi-cluster cluster tools to illustrate the proposed event graph based simulation and scheduling analysis.