BATCHING AND SCHEDULING AT BATCH PROCESSING WORKSTATION IN A SEMICONDUCTOR FABRICATION FACILITY PRODUCING MULTIPLE PRODUCT TYPES WITH DISTINCT DUE DATES

摘要

This paper focuses on scheduling problems at batch processing workstations in a semiconductor wafer fab producing multiple-type products that have different due dates and different process flows. A batch processing workstation consists of parallel identical machines, each of which processes several wafer lots of the same recipe at the same time. What need to be determined in the scheduling problem considered here are how to group wafer lots into batches and when to process these batches for the objective of minimizing the total tardiness of the orders. Two new rules are developed based on the idea that waiting times of urgent lots have to be minimized for these lots to be completed as early as possible. Simulation experiments are carried out to compare new rules with the minimum batch size (MBS) rule, which is widely used in practice. Results show that new rules work better than the MBS rule.