Thermodynamic analysis of chemical vapor deposition of BCl₃-NH₃-SiCl₄-H₂-Ar system

The thermodynamic phase stability area diagrams of BCl₃-NH₃-SiCl₄-H₂-Ar system were plotted via Factsage software to predict the kinetic experimental results. The effects of parameters (i e, partial pressure of reactants, deposition temperature and total pressure) on the distribution regions of solid phase products were analyzed based on the diagrams. The results show that: (a) Solid phase products are mainly affected by deposition temperature. The area of BN+Si₃N₄ phase increases with the temperature rising from 650 to 900 °C, and decreases with the temperature rising from 900 to 1 200 °C; (b) When temperature and total pressure are constants, BN+Si₃N₄ phase exists at a high partial pressure of NH₃; (c) The effect of total system pressure is correlated to deposition temperature. The temperature ranging from 700 to 900 °C under low total pressure is the optimum condition for the deposition. (d) Appropriate kinetic parameters can be determined based on the results of thermodynamic calculation. Si–B–N coating is obtained via low pressure chemical vapor deposition. The analysis by X-ray photoelectron spectroscopy indicates that B–N and Si–N are the main chemical bonds of the coating.