Proceedings of the 2011 Winter Simulation Conference S. Jain, R.R. Creasey, J. Himmelspach, K.P. White, and M. Fu, eds. SIMULATING CONVEYOR-BASED AMHS LAYOUT CONFIGURATIONS IN SMALL WAFER LOT MANUFACTURING ENVIRONMENTS Leanna Miller Alger Bradley Ashley Tish Tongdan Jin Jesus A. Jimenez Robert Wright Texas State University-San Marcos Freescale Semiconductor, Inc. Ingram School of Engineering 6501 William Cannon Drive West 601 University Drive Austin, TX 78735, USA San Marcos, Texas 78666, USA ABSTRACT Automated material handling systems (AMHS) using conveyors have been recently proposed as a tech- nology option for next generation wafer fabrication facilities. This technology seems to provide an in- creasing capacity for moving and storing wafers in a continuous flow transport environment. The goal of this research is to design and test conveyor-based AMHS configurations, which include turntables and storage areas near the processing equipment. Simulation models were developed in AutoMod to deter- mine the best conveyor layout, with emphasis in comparing centralized versus distributed storage sys- tems. The AMHS factors under study comprise the number, location, and capacity of the storage areas. Simulation results show that the distributed storage approach provides improved performance; however, these systems require more capital investment than that needed for the centralized storage approach. 1 INTRODUCTION International SEMATECH Manufacturing Initiative (ISMI) launched the Next Generation Factory (NGF) program; this program aims to decrease the costs of the wafer processing facility (fab) by 30% and lower the wafer cycle time by 50% (ISMI 2011). NGF’s emphasis is on improving the fab and equipment productivity by implementing small lot manufacturing environments, improving predictive and preventive equipment maintenance capabilities, enhancing equipment quality assurance, reducing equipment setups, improving flow of wafers to equipment, among others projects. Small lot manufacturing (SLM) is a semiconductor manufacturing initiative that seeks to reduce the lot sizes from 25 wafers to 12 wafers per processing batch. SLM has shown significant improvements in the cycle time of high-product mix fabs (Bass and Wright 2008). However, the automated material handling system (AMHS) is a potential factor that will inhibit the productivity of such environments. For the purposes of the AMHS, each processing batch of 12 wafers is transported inside a front opening unified pod (FOUP), referred herein as a wafer carrier. Studies have shown that vehicle-based AMHS may become too congested in 12-wafer-lot systems due to the increased move requirements and high dependence on stockers (Jimenez et al. 2010). Conveyor-based AMHS are emerging as an alternative to existing vehicle-based AMHS for providing high-speed, high-throughput deliveries (Pettinato and Pillai 2005). Due to the higher availability of conveyors, the delivery time variability will be lower than in vehicle-based AMHS. The main reason is that in a vehicle-based system, a wafer carrier waits for a considerable amount of time at the tool port to 1944 978-1-4577-2109-0/11/$26.00 ©2011 IEEE