Part I of the paper was concerned with the influence of the surface area/volume ratio, [A S /V R ], temperature, and residence time on the deposition rate of silicon carbide from a 1:4 methyltrichlorosilane (MTS)/hydrogen mixture. In Part II, the composition of the gas phase and the deposit are investigated. It is shown that deposition rate maxima at about 900 C and 1025 C, frequently reported in the literature, result from a temperature-selective deposition of both SiC and Si. This selectivity is determined by the [A S /V R ] ratio because it controls the interaction of the gas phase and surface reactions. At a sufficiently high [A S /V R ] ratio, deposition of free silicon is completely suppressed and the rate maxima disappear simultaneously. Increasing the temperature generally favors deposition of stoichiometric silicon carbide. Results for the gas phase composition are used to discuss changes of gas phase chemistry responsible for the deposition of free silicon, as well as of stoichiometric silicon carbide. Higher chlorosilanes, as well as carbochlorosilanes, are postulated as intermediates of silicon and silicon carbide deposition, respectively.

The CVD of silicon carbide from methyltrichlorosilane (MTS) was studied at various surface area/volume ratios, using an MTS/H 2 mixture of 1:4. The total pressure was 90 kPa; the temperature was varied from 800 C to 1100 C at residence times of 0.9 s and 0.4 s. Steady-state deposition rates were determined as a function of reactor length. The deposition rate as a function of temperature, investigated at a low surface area/volume ratio, shows strong and weak intermediate maxima at temperatures of about 900 C and 1025 C, respectively. These maxima decrease at increasing surface area/volume ratio, leading to a continuous increase of the deposition rate at a sufficiently high surface area/volume ratio. A chemical model based on analyses of the deposits and the gas phase compositions is presented in Part II.