Initial decomposition of methyltrichlorosilane in the chemical vapor deposition of silicon-carbide

All of the possible initial decomposition pathways in the CVD process of preparing silicon carbides with CH3SiCl3–H2 precursors were searched theoretically. The geometries of the species were optimized with B3PW91/6-311G(d,p). The energy barriers and the reaction energies were evaluated with the accurate model chemistry at G3(MP2) level after a non-dynamical electronic correlation detection. The Gibbs free energies at 298.15 K and 1200 K for all the possible elementary reactions, including both direct decomposition and the radical attacking dissociations for MTS were reported. Nine transition states are firstly reported in initial decomposition of MTS. Comparisons with a previous theoretical study are excellent, but additional reactions studied here are found to be relevant as well.