Nucleation behavior during the first stages of SiC growth on different substrates

Abstract
SiC films were deposited on bare Si(001), on MBE carbonized Si(001) and on thermally oxidized (300 nm thick) Si(001) to investigate the effect of the substrate surface on the nucleation behaviour and the subsequent SiC growth mode. The SiC film depositions were performed in a conventional hot-wall LPCVD reactor at temperatures around 1150°C. The precursor gas used was tetramethylsilane (TMS) mixed with H₂. Extensive morphological and structural characterization was carried out by AFM, SEM, XRD (rocking curves and texture measurements), WDS and TEM. The influence of the different nucleation surfaces on the quality of the grown film and its microstructure is discussed. On both bare Si and MBE carbonized substrates, a very thin film covers the substrate surface even after very short times. The presence of voids and hillocks on these samples is associated to Si-outdiffusion during the SiC growth. The resulting thick layers grown for longer times are single-crystalline 3C-SiC. On the contrary, SiC growth on thick SiO₂ proceeds via the formation of hexagonal pyramidal islands, which coalesce after very long deposition times.