Infrared study of carbon incorporation during chemical vapor deposition of SiC using methylsilanes

We use infrared absorption spectroscopy (IRAS) in the multiple internal reflection geometry to investigate the carbon incorporation during chemical vapor deposition of SiC on Si(1 0 0) using methylsilanes, SiHx(CH3)4−x (x=1–3). We have measured IRAS spectra in the SiH stretching vibration region of the Si(1 0 0) surface that was dosed with methylsilanes at temperatures ranging from 300 to 500°C. IRAS data demonstrate that at temperatures below 400°C, methylsilane is thermally decomposed to form a doubly occupied dimer (DOD, HSi–SiH) and a mixed adatom dimer (HSi–SiH). At higher temperatures, carbon atoms that are released from the methyl group, attack the backbonds of surface Si atoms to generate amorphous carbon-incorporated layers that include Si atoms having two or three C atoms bound to them. It is found that the carbon incorporation is enhanced with the increase of the number of methyl groups of methylsilane.