LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION (LPCVD) OF BETA-SIC ON SI(100) USING MTS IN A HOT-WALL REACTOR

Stoichiometric beta - SiC thin films with a high preferred orientation of (111) planes were successfully deposited on Si(100) substrates at a relatively low temperature of 1050-degrees-C from the mixture of methyltrichlorosilane (CH3SiCl3 or MTS) and H-2 in a hot wall LPCVD reactor. No etching of the Si substrate and smooth topography of the deposit were observed at high H-2/MTS ratios and/or low deposition pressures. The presences of excess silicon, excess carbon, or incorporated hydrogen atoms in the films were not detected. Poor topography, degradation in preferred orientation, and etching of the Si substrate were observed at high va lues of deposition pressure, MTS concentration, and temperature. The etching on the Si substrate was due to the out-diffusion of Si atoms from the substrate and the presence of Cl-containing radicals resulting from the decomposition of MTS molecules while transporting to the Si substrates. A deposition mechanism was proposed to model the deposition of SiC in a hot wall reactor by using (1) gas phase decomposition of MTS molecules, (2) adsorption of the intermediates on the surface, and (3) reaction of the adsorbed intermediates to form SiC. The deposition rates were predicted very well for various deposition conditions in a hot wall LPCVD reactor.