Formation of microcrystalline SiC films by chemical transport with a high-pressure glow plasma of pure hydrogen

The formation of microcrystalline 3C-SiC films on Si substrates by the plasma-enhanced chemical transport method was investigated using a pure hydrogen glow plasma at 0.027 MPa. In this method, no source gas was necessary. Instead, the erosion products of a sintered 3C-SiC plate in a hydrogen plasma were used as the deposition source. By Fourier transform infrared (FT-IR) absorption gas analysis, the species generated by the hydrogen etching of sintered SiC were found to be SiH4 and CH4, which can serve as precursors for SiC film formation. The etch rate of sintered SiC by hydrogen plasma decreased with increasing source temperature. The maximum etch rate of the sintered SiC was 450 nm/min at an input power of 47 W/cm2. Films prepared by this method at substrate temperatures (Tsub) of 600 and 1073 K were analyzed by FT-IR absorption spectroscopy. An absorption peak at 800 cm- 1 related to Si–C bonds was clearly observed, but no significant hydrogen-related absorption peaks, such as C–H and Si–H, were observed in the prepared films. The deposition rate of SiC was about 8 nm/min, independent of Tsub. The SiC films had a columnar structure, and their surface morphologies revealed faceted growth. With decreasing Tsub, the lateral grain size became large. The current–voltage characteristics of a prepared SiC/Si heterojunction np diode showed rectifying behavior, demonstrating that the doping of an SiC film can be achieved without a doping gas source. The dopant distribution near the SiC/Si interface deduced from capacitance–voltage measurements suggests that the precise control of the initial growth stage is important to obtain a good SiC/Si interface.