Analysis of gaseous species in chemical vapor deposition of SiC from MTS/H₂

Qualitative and quantitative analyses were carried out to investigate the effect of the deposition temperature, pressure and flow rate of chemical vapor deposition imposed on the concentrations of MTS/H₂ CVD SiC gaseous species through GC/MS method. Decomposition procedures of MTS in H₂ based on the reaction rate and concentrations of species were analyzed. The results show that: (1) the identified gaseous species are CH₄, C₂H₆, C₂H₄, C₃H₆, C₂H₂, MTS, SiCl₄ and CH₃SiHCl₂, of which the concentrations of CH4 and SiCl₄ are comparatively higher; (2) temperature, pressure and flow rate have great effect on the concentrations of gaseous species, and their regular patterns follow the same dependence as the thermodynamics; (3) MTS mainly starts with the cracking and decomposition of Si-C, and experiences three stages, the reaction with H₂, the formation of middle objects and also by-products. It is suggested that the main formation route of alkane is CH₃→C₂H₆ →C₂H₄→C₂H₂.