Metaheuristic scheduling of 300-mm lots containing multiple orders

The standard unit of transfer in new semiconductor wafer fabrication facilities is the front opening unified pod (FOUP). Due to automated material handling system concerns, the number of FOUPs in a wafer fab is kept limited. Moreover, a certain number of new and larger 300-mm wafers will be placed in these FOUPs and this makes grouping orders from multiple customers into a job a necessity. Thereby, efficient utilization of the FOUP capacity while attaining good system performance is a challenge. We previously investigated optimization-based solution approaches for minimizing total weighted completion time and maximizing on-time delivery performance for the single machine multiple orders per job scheduling problem. We present two metaheuristic solution approaches for this scheduling problem under two different typical wafer fab machine environments: single unit processing and single lot processing. Experimental results demonstrate that the metaheuristic approaches can find near-optimal solutions for realistic-sized 300-mm scheduling problems in an acceptable amount of computation time.