Research on scheduling of cluster tools with residency time

Because of residency time constraits for cluster tools, it is very difficult to schedule them. This paper addresses their scheduling issues and conducts their schedulability and scheduling analysis. A linear programming model with temporal constraints of dual-blade robot and processing modules is developed. With the model, the cycle process of the dual-blade robot and processing module is analyzed. Based on the model and the analysis, necessary and sufficient conditions under which the system is schedulable are presented. At the same time, the control strategy to make the non-schedulability scheme into schedulable scheme is discussed by means of decreasing the processing mudule number and choosing the appropriate processing time. The simulation results show that the mentioned model and control strategy is helpful to decrease the number of the test wafers and to increase the wafer productivity.