We have investigated the evolution of the microstructure, growth modes, and growth kinetics of β-SiC in a rapid thermal processor using FTIR, ESCA, and TEM. SiC layers were formed by reacting C2H4 with Si substrates between 900 and 1300°C at 5 torr. We found that SiC forms discrete nuclei at 900°C, a mixture of discrete nuclei with a thin β-SiC layer in between those nuclei at around 1000°C, and a continuous β-SiC layer above 1100°C. In all cases, β-SiC grows epitaxially on Si substrates. In addition, we identified that a graphitic carbon layer is formed on top of a continuous β-SiC layer. The thickness of the SiC layer was deduced from the integrated absorption spectra of FTIR and measured from the high resolution cross-sectional TEM micrographs. Kinetic data indicate that SiC grows rapidly at the initial stages of reaction. The growth rate, however, is retarded significantly as the reaction proceeds.