Stepwise Reaction for Chemical Vapor Deposition of Stoichiometric SiC Films Using Methyltrichlorosilane and Hydrogen as Reactants

The film growth mechanism of stoichiometric SiC in a chemical vapor deposition reaction system using methyltrichlorosilane (MTS) and hydrogen (H2) as the reactants was investigated. Kinetic analysis of the film growth rate profiles was performed in two distinct reactors, a hot-wall tubular reactor and a macrocavity reactor. Macrocavity experiments at 1273 K revealed that MTS reacts at the substrate surface with a low sticking probability of 2.1 × 10–6, while the film growth is primarily contributed by the gas-phase reaction of the reactants. Moreover, the tubular reactor exhibited a unique film growth rate profile, featured by an initial increase followed by a decrease along the gas flow direction. This observation strongly suggested a stepwise reaction in which MTS/H2 reacts in the gas phase to form an intermediate species, which then contributes to film growth by reacting at the substrate surface. The apparent sticking probability of the gaseous intermediate species, derived from the best-fit surface reaction rate constant to the proposed stepwise reaction mechanism, was found to be approximately 1 × 10–3. The obtained sticking probability, being 3 orders of magnitude higher than that of MTS, indicated that the gaseous intermediate species may consist of a MTS/H2-derived active species that maintains the original Si–C bond structure, thereby leading to the stoichiometric SiC film growth.