A Lot Dispatching Strategy Integrating WIP Management and Wafer Start Control

Abstract

Compound priority dispatching (CPD) is a new dispatching strategy for semiconductor wafer fabrication. It takes into account both work-in-progress (WIP) management and wafer start control. The compound priority of wafers is calculated based upon fab wafer start status, the current processing step, and the amount of WIP in the current, the upstream, and the downstream steps. Simulation results demonstrate that, for a given fab model, CPD can reduce the mean total queue time (MTQT) by 50% and increase the throughput rate by 20% compared with first- in-first-out (FIFO) and shortest remaining processing time (SRPT) scheduling (dispatching) strategies.