A new scheduling approach using combined dispatching criteria in semiconductor manufacturing systems.

摘要

Today's highly competitive semiconductor markets place a greater emphasis on responsiveness to customers. In the past competition has been primarily in the product design arena but in the last several years, short lead times and high on-time delivery performance have become equally important to winning customer satisfaction. To meet these criteria, the recent thrust of manufacturing management has been on using effective scheduling techniques to manage wafer movement. Dispatching policies are the most common scheduling tools used in wafer fabs today due to the complexity of the scheduling problem. Most previous research has focused on the use of single dispatching criteria, such as Critical Ratio (CR), to optimize factory performance. None of these single rules has proven completely satisfactory for a wafer fab. They also lack the capability to handle multiple re-entrant flows to effectively balance the line output and only focus on a single performance measure. This research proposes a new dispatching approach that combines different criteria together into a single rule. The objective is to simultaneously optimize the different responses. This is accomplished using a linear combination with relative weights. The weights' assignments are optimized using desirability functions. The responses of interest in this research are on time delivery, variance of lateness, cycle time and variance of cycle time. Results demonstrate that the proposed approach is superior to the use of single dispatching criteria. The results show an average of 20% improvement for all responses.