EPITAXIAL-GROWTH OF BETA-SIC ON SI BY RTCVD WITH C3H8 AND SIH4

The structural properties of beta-SiC thin films grown on (100) Si by rapid thermal chemical vapor deposition (RTCVD) are reported. SiC growth was achieved bv the reaction of SiH4 (5% in H-2) and C3H8 (5% in H-2) from 1100 to 1300-degrees-C. The SiC growth was preceded by the formation of a carbonization buffer layer at 1200 to 1340-degrees-C. SiC growth rate of 0.5 to 1 nm/s was obtained. The SiC films were evaluated by X-ray diffraction, ellipsometry, SEM, and TEM analysis. From a structural point of view, the optimum conditions for carbonization were obtained at a temperature of 1300-degrees-c a temperature ramp-up rate of around 50-degrees-C/s, a C3H8 flow rate of 11 sccm accompanied bv 1.5 lpm H-2 flow. Optimum conditions for subsequent SiC growth were obtained at 1200-degrees-C, 11 sccm C3H8 flow rate, 13 sccm SiH4 flow rate, and 1.5 lpm H-2 flow rate. Both X-ray and electron diffraction indicated a single-crystal expitaxial cubic SiC thin film. The 2-theta peak at 41.44-degrees characteristic of (100) SiC had a full width at half maximum (FWHM) signal of 0.18 to 0.22-degrees. The propane flow rate has been observed to have a strong effect on the SiC film thickness. morphology, and void formation. A possible mechanism for this phenomenon has been proposed based on nucleation site density and Si surface diffusion.