Behavior of oxygen doped SiC thin films: An x-ray photoelectron spectroscopy study

Thin silicon carbide films have been deposited by chemical vapor deposition on p-type (100) silicon substrates. The composition and bonds formed in th ese films have been analyzed by x-ray photoelectron spectroscopy (XPS) and infrared spectroscopy. The native surface oxide on the silicon carbide surf ace induced by air exposure has also been studied. Several phases are detec ted in the near-surface region: elemental Si, Si oxides (mainly SiO2), Si c arbide (SiC) and Si oxicarbides (SiOxCy). Quantitative XPS analysis results indicate that, for atomic oxygen fractions <0.15, the Si-C phases are domi nant in the films. Above this value no silicon oxicarbide is observed, but a multiphase material formed by elemental Si, Si oxides and Si carbides is observed. In spite of the film being a complex phase mixture, a simple rela tionship is found between the overall carbon and oxygen compositions. The c arbon atomic fraction in the film decreases quasilinearly as the oxygen con tent increases, with a slope of about -1. An overall composition of SiOxC3- x in the 0.5 <x <2 range is found for the phase mixture. A comparison with silicon carbide obtained by CHn+ ion implantation into monocrystalline sili con is made. (C) 2001 American Institute of Physics.