Thermodynamic calculation for the chemical vapor deposition of silicon carbonitride

In order to tailor the phase composition of silicon carbonitride (SiCN) by chemical vapor deposition or chemical vapor infiltration (CVD/CVI), it is necessary to set up a series of phase diagrams at a larger temperature range from 800 K to 1800 K using SiCl4, NH3, CH4/C3H6 and H2 as precursors. The equilibrium conditions of thermodynamic calculation were determined by temperatures, total pressures, dilute gas H2 and molar ratios of reactants. CVD phase diagrams provide a qualitative description of phase composition, while the deposition efficiencies directly give the conversion extent from precursors to condensed phases. The low temperature phases (Si3N4, C) and high temperature phase (SiC) are also proved by thermodynamic calculation of CVD SiCN, which gives a clear way to conduct the experiments.