Thermodynamic calculations and kinetic verifications on the chemical vapor deposition process of Si-C-N ceramic from the SiCl₃CH₃-NH₃-H₂-Ar precursors

Based on the Gibbs principle of minimum free energy and Factsage software, the thermodynamic phase diagram and three-dimensional yield map were firstly calculated from the SiCl₃CH₃-NH₃-H₂-Ar system. The effects of temperature, total pressure, reactant ratios of 3[NH₃]/[SiCl₃CH₃] and [H₂]/[SiCl₃CH₃] on the formation and yield of condensed phases were discussed. Predominant condensed phases at equilibrium were SiC, Si₃N₄ and graphite phases. The concentration of condensed phase products was used to confirm the composition of Si-C-N. Through the kinetic verification at 1173.15 K, it could be demonstrated that Si-C-N ceramics are obtained by chemical vapor deposition from the SiCl₃CH₃-NH₃-H₂-Ar system. The deposits were amorphous and mainly constituted by C-C, Si-N and Si-C bonds from XPS analysis, which were well consistent with the results of thermodynamic calculation. The real part and the imaginary part of permittivity were approximately 4 and 0, respectively, which indicated the amorphous deposits possess the low dielectric constant and loss.