Scheduling cluster tools in wafer fabrication using candidate list and simulated annealing

This paper presents a new method for scheduling cluster tools in semiconductor fabrication. A cluster tool consists of a group of single-wafer chambers organized around a wafer transport device, or robot. The cluster fabrication considered consists of serial cluster tools. Due to constraints imposed by multiple routes of each type of wafer and machines with no buffer, it is very difficult to find an optimal or near-optimal schedule. The proposed method uses a job requirement table with random keys as a solution representation, and simulated annealing to find an optimal or near-optimal schedule. To determine which operation can be scheduled, a candidate list is used. To show the effectiveness of the proposed method, a scheduling example of cluster fabrication is presented. From the experimental results, it is shown that the proposed method is promising.