Composition and structure of epitaxial β-SiC films grown by reactive magnetron sputtering on Si(100) substrates

Abstract

Epitaxial β-SiC films have been grown on Si(100) substrates by reactive magnetron sputtering in mixed ArCH₄ discharges as a function of substrate temperature T_s (700–1200 °C) and methane partial pressures PCH₄ (0.1–1.6 mTorr). Auger electron spectroscopy showed that the carbon content in the films depends on both PCH₄ and T_S. Thus, the deomposition of the CH₄ molecules, necessary for SiC formation, occurs both through plasma decomposition and through pyrolysis. X-ray diffraction of asdeposited films grown at T_S>900°C showed only the β-SiC phase with a pronounced (200) preferred orientation. Cross-sectional transmission electron microscopy showed that films grown at 700°C consist of a microcrystalline-to-amorphous mixture of β-SiC and silicon. At T_S=900°C, highly (200) oriented single-phase β-SiC films were obtained with relatively sharp interface to silicon, but with stacking faults originating at the silicon interface and propagating throughout the film. Films grown at T_S=1000 and 1100°C were strongly (200) oriented but with rough interface and a faceted top surface. Also these films contained a high density of stacking faults. The interfacial reaction was also studies by exposing heated silicon surfaces (T_S=1200°C) to a CH₄ atmosphere. After 10 min exposure at PCH₄= 1.5 mTorr a converted epitaxial β-SiC layer about 50 nm thick formed with a rough interface and a faceted surface. Also these layers contained a high density of stacking faults.