Local Equilibrium Phase Diagrams for SiC Deposition in a Hot Wall LPCVD Reactor

Abstract

AbstractThe traditional CVD phase diagrams are only valid for cold wall reactors because of the neglecting of the depletion effects in hot wall reactors. Due to the depletion effects along the reactor, the traditional CVD phase diagrams can not accurately predict the phases deposited on the substrate in a hot wall CVD system. In this paper, a new approach to calculate the local equilibrium CVD phase diagrams in a hot wall reactor is presented by combining the depletion effects with the equilibrium thermodynamic computer codes (SOLGASMIX–PV). In this study, the deposition of SiC using methyltrichlorosilane (MTS)–hydrogen (H2) was chosen to verify this new approach. The differences between the new CVD phase diagrams and the traditional phase diagrams were discussed. The calculated CVD phase diagrams were also compared with the experimental data. The single phase of SiC predicted by this approach is much better than the traditional phase diagrams. The experimental regions for depositing single phase SiC are larger than the calculated local phase diagrams because of the higher linear velocity of the gas flux under low pressure and the polarity of the Si carrying intermediate species.