Reservation based dispatching rule for wafer FAB with engineering lots

Presented in this paper is a dispatching rule for engineering lots by a wafer FAB. The proposed rule uses the concept of reservation to ensure greater capacity for the engineering lots. Although a reservation based rule was previously proposed by one of the authors, it has remained difficult to ensure the necessary capacity for the engineering lots because of variations in the processing time for each step of the process. In this paper, we enhanced the previously proposed rule to reflect the fact that batch tools often cause bottlenecks because of their long processing times. We developed a FAB model using the Measurement and Improvement of Manufacturing Capacity (MIMAC) dataset 6, and performed simulations with MozArt®. The simulation results clearly show the advantages of the enhanced reservation based dispatching rule over the previous version of the rule and that it is vital to identify an appropriate reservation range.