Identification of film-forming species during SiC-CVD of CH₃SiCl₃/H₂ by exploiting deep microtrenches

The surface reaction kinetics of chemical vapor deposition (CVD) of silicon carbide (SiC) from methyltrichlorosilane (MTS; CH₃SiCl₃) and hydrogen were studied to identify gaseous species contributing to SiC film formation. First, SiC was deposited into relatively deep microtrenches with aspect ratios of up to 64:1, and the film-thickness profiles within the deep microtrenches were analyzed to evaluate the sticking probabilities (η) of the film-forming species. Two film-forming species were identified with η of 10^–2 and 10^–5 at 1,000°C. Next, their partial pressures at several positions in the reactor were estimated from their respective η and deposition rates. The low-η species was identified as MTS by comparing the partial pressure measured by quadrupole mass spectrometer with that calculated by elementary reaction simulations. Similarly, the high-η species was likely CH₂SiCl₃ generated via gas-phase decomposition of MTS. Such identification is crucial to optimize the deposition conditions and also design of a reactor.