In this study we first explain details of the semiconductor manufacturing processes and cluster tools. Then we discuss the problems in current fab layout and cluster tool architecture. As a solution to these problems, we propose the ILE (In-Line EFEM) architecture in which wafer movements are conducted through interconnected EFEMs (Equipment Front End Modules) instead of AMHS (Automated Material Handling System). Then we model the pilot ILE system using discrete event simulation and analyze the cycle time. Finally we compare three different scenarios of equipment layout in the ILE system in terms of cycle time.