Anisotropy of silicon carbide crystal : Approaches in terms of surface process and high-temperature oxidation

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The anisotropy of physical and chemical properties of silicon carbide (SiC) crystal was investigated with the approaches in terms of surface process and high-temperature oxidation.1.Oxidation of SiCOxidation kinetics of CVD-SiC and single crystalline SiC in ozone-containing atmospheres at temperatures from 573 to 1273K up to 345.6ks were evaluated by the measurement of oxide thickness on the specimen. The oxidation rate of (0001^^_) C face in the ozone-containing atmospheres was much higher than that of (0001) Si face as well as in oxygen atmosphere previously reported. The measurement of the oxidation rates of single crystalline SiC revealed that the order of the oxidation rates was (0001^^_)> (12^^_10) >(101^^_0)> (0001). This order well corresponds to the density of carbon on the individual face. The oxidation rate on (0001) Si face in the ozone-containing atmospheres relatively increased compared with that in other oxidation atmospheres such as dry oxygen or wet oxygen. This result suggests that the use of ozone gas as oxidant in semiconductor device fabrication process might be effective for rapid oxidation at low temperatures.2.Surface process in SiCNegative crystal was introduced into the SiC single crystal. The shape change of the negative crystal was measured at 2473 K. The faceting of the negative crystal suggested that {0001} was stable face, a part of the Wulff shape, while {121^^_0} was unstable face, not a part of Wulff shape. The rate of shape change of the negative crystals obtained in the experiments was compared with that calculated using the model, in which the driving force of shape change assumed to be the difference of chemical potential on the surface. The rate controlling process of shape change was the surface attachment limited kinetics (SALK) for on-axis face, while the. contribution of surface diffusion on the rate controlling process was suggested for off-axis face.