Abstract
Semiconductor wafer fabrications are modeled as a re-entrant flow shop problem, in which the processing order of each lot is given, but each lot may enter a production line many times. Hence, a re-entrant flow shop is a very complicated problem, which has a property similar to a job shop problem. In this paper, we consider a scheduling method for a whole production line of re-entrant flow shop. A real wafer fabrication line consists of several hundreds of processes and requires re-scheduling many often. So we propose local search methods instead of seeking exact solutions. Some numerical results indicate that the proposed methods obtain good solutions in a short time.
