Multiple orders per job formation and release strategies in large-scale wafer fabs: a simulation study

Abstract

In this paper, multiple orders per job type formation and release strategies are described for semiconductor wafer fabrication facilities (wafer fabs). Different orders are grouped into one job because orders of an individual customer very often fill only a portion of a Front-Opening Unified Pod (FOUP). After job formation, an FOUP is assigned to each job and is used to move the job throughout the wafer fab. We determine an acceptable number of FOUPs given a prescribed order release rate to find appropriate values for on-time delivery performance measures, cycle time, and throughput by discrete event simulation. On the other hand, given a prescribed number of FOUPs and target values for these performance measures, we look for an appropriate order release rate. Simulation experiments with models for large-scale wafer fabs are performed to solve these two problems. We also discuss a complementary analytical method to determine an appropriate number of FOUPs in some specific situations.

Keywords:

• multiple orders per job
• semiconductor manufacturing
• simulation
• CONWIP

Acknowledgements

The authors gratefully acknowledge the simulation efforts of Alex Horn. This work was initiated while the first author was visiting the Arizona State University Modeling and Analysis of Semiconductor Manufacturing (MASM) Lab in spring 2007.