SURFACE CHEMISTRY DURING SiC EPITAXIAL GROWTH USING ORGANO-SILANES

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SiC is a promising material for the next-generation power devices. This research, aiming at clarifying the surface chemistry during SiC epitaxy using organo-silanes as well as developing a low-temperature, high-quality SiC epitaxy, has yielded the following results.(1) Suppression of Si out-diffusion by using Organo-Silane method: By using an organo-silane as the source gas, which contains a chemically stable Si-C bond within the molecule, the out-diffusion of the Si atoms from the substrate was found to be greatly suppressed.(2) Development of OS-buffer method: In SiC/Si heteroepitaxy, a buffer interlayer is a must to moderate the 20% lattice mismatch between the SiC film and the Si substrate. Formerly, the buffer layer was formed with the carbonization method. The high temperature (〜900℃) required in the process, however, caused harmful surface roughness and voids in the Si substrates. In this study, a new method, named OS-buffer method, has been developed, in which organo-silane gas … More es are used to form the buffer layer in place of hydrocarbon gases. As a result, qualified bufferlayers can be grown at 600℃.(3) Development of OS-GSMBE method: Instead of using a pair of Si- and C-source gases as in the conventional SiC epitaxy, a single source of organo-silane gas was successfully used to grow qualified SiC epitaxial films. As a result, the growth temperature could be reduced from the former 1100℃ to 900℃. Surface hydrogen was also found to be harmful in obtaining qualified films.(4) Obtaining a single-domain SiC film on Si: The resistive heating method was found to be effective in obtaining a single-domain SiC film on Si substrates(5) Modeling of the Si growth: By obtaining the growth rate and the hydrogen coverage at the growing surface as a function of both the substrate temperature and the disilane pressure, the growth kinetics for the Si GSMBE has been clarified. Based on the result, a new growth model has been developed, which accounts for both the temperature- and the pressure-dependence of the growth rate unifiedly. Less