Analysis and Control of Wafer Delays in a Dual-Armed Cluster Tool for a K-Cyclic Schedule

Abstract

We examine wafer delays, particularly the worst-case delay, of a dual-armed cluster tool for a K-cyclic schedule. We propose two useful concepts related to robot operations for the analyses, which are the time difference sigma and the robot delay R. By using these concepts, we formulate a mixed-integer linear programming for computing the worst-case wafer delay. An upper bound for the worst-case wafer delay and experimental results are suggested. We also suggest an improved wafer delay regulation method by exploiting workload balancing. We introduce the effects of workload balancing and the strategies for achieving workload balancing. Explanations related to the configuration of the tool also are suggested.