CVD reactor design using three-dimensional computer simulation - Gas outlet effect

Chemical vapor deposition (CVD) films are widely used to make Very Large Sc ale Integrated Circuits (VLSIs). For optimum VLSI performance, precise cont rol of both film thickness and composition is required. For this purpose, w e carried out three-dimensional computer simulation of WSix CVD processes u sing WF6-SiH4 source gases in a cold-wall and single wafer type reactor. Fo r this simulation we used the reaction model, the radical chain reaction mo del for CVD film formation developed by using analysis of the reaction kine tics from the results in the simplified reactor. By this simulation, agreem ent between simulated and measured values was approximately 5%. On the basi s of this result, we investigated the effect of gas outlet number and outle t height position on the radial distribution of film deposition rate, compo sition and uniformity. When we selected the suitable outlet height position , the variation was improved remarkably less than 4%. This tendency might b e explained by the gas velocity and gas composition distribution in the rea ctor. These results demonstrate how CFD simulations can be used to optimize CVD reactor design.