Control of Wafer Slot-Dependent Outgassing Defects during Semiconductor Manufacture Processes

In this paper, a study on a behavior of waiting-time related defect which strongly depends on a wafer slot position in FOUP (Front Opening Unified Pod) was carried out. The occurrence of the waiting-time dependent defects in the processing tools was found to be affected by the flow pattern, moisture and process outgassing distribution in equipment EFEM (Equipment Front End Module) and FOUP. In order to control this problem, which also causes to deteriorate the production yield, it is essential to establish a system that is capable of monitoring the wafer-level waiting- time of each wafer in the processing tools. Optimizing the flow pattern of air which contains humidity and process outgassing or AMC (Airborne Molecular Contaminants), and N2 purge gas in EFEM and FOUP is required as well. Various types of load-port N2 gas purging system inside EFEM and FOUP were reviewed using CFD (Computational Fluid Dynamics) simulations and a fully charged N2 circulating EFEM exhibited the best defect control performance.