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 800K to 1800K 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.