INFLUENCE OF H-2 ADDITION AND GROWTH TEMPERATURE ON CVD OF SIC USING HEXAMETHYLDISILANE AND AR

Growth of cubic SiC has been carried out on Si (111) and (100) substrates and on 6H-SiC Lely crystals using chemical vapor deposition at atmospheric pressure. Hexamethyldisilane (HMDS) was used as the only precursor and pure Ar or a nonflammable mixture of 4% H-2 in Ar was used as the carrier gas. The crystallinity was characterized by x-ray diffraction and transmission electron microscopy, while the stoichiometry was revealed by Auger electron spectrometry (AES). It was found that polycrystalline layers were obtained at low growth temperatures and with pure Ar as the carrier gas, while the crystallinity improved at temperatures above 1300 degrees C and when H-2 was added. Under optimum growth conditions most of the grains are oriented with parallel epitaxy or with twinned epitaxy with respect to the substrate. In every case, however, there are some grains which are randomly oriented. The AES data show carbon accumulation on the surface of thick SiC layers. It thought that the major problem in growing single-crystalline SiC with HMDS in a H-2-poor atmosphere is the presence of excess carbon.