Modeling of the Evolutions of Negative Ions in Silane Plasma Chemical Vapor Deposition for Various Process Conditions

概要

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The evolutions of negative ions in the silane plasma chemical vapor deposition (PCVD) reactor for semiconductor processing were analyzed, considering the effects of chemical reactions, fluid convection, diffusion and electrical migration. The 23 plasma chemical reactions and 18 chemical species which might be important for the evolutions of negative ions were considered in this analysis. The governing equations were solved numerically. Most of the negative ions are located in the bulk plasma region and the concentrations of negative ions are almost zero in the sheath regions, as they are expelled from the sheath regions to the bulk plasma by electrostatic repulsion. The concentrations of negative ions at the downstream sheath boundary were higher than those at the upstream sheath boundary due to the effect of convection. As the reactor pressure increases, the concentrations of neutrals and positive ions increase, but the concentrations of negative ions decrease, based on the reaction chemistry proposed in this study. As the electric field strength increases, the negative ion concentrations increase, because more negative ions are contained in the bulk region by the stronger electrostatic repulsive forces.
Publication Office, Japanese Journal of Applied Physics, Faculty of Science, University of Tokyoの論文
1997-07-30