A novel silicon-carbon precursor for oligomer chemical vapor deposition of silicon carbide for harsh environmental applications

Silicon carbide (SiC) films have been successfully deposited on various substrates by oligomer thermal chemical vapor deposition (OTCVD) from a novel, halogen free, oligomer precursor family of polysilyenemethylenes (PSMs) called SP-4000. The high quality films were grown at substrate temperatures in the range of 620degreesC to 850degreesC and at process pressures in the range of 1 - 200Torr. SP-4000 is a silicon carbide precursor with formula [-SiH2-CH2-](n), n=2-8, composed of an alternating silicon and carbon backbone with hydrogen side groups. Depositions on Si and graphite substrates yielded SiC films with Si/C ratios in the range 1.1 to 1.2 and thicknesses in the range 0.3 to 50 mum. Structural and chemical characterizations were performed by Auger electron spectroscopy (AES), x-ray diffraction (XRD), nuclear reaction analysis (NRA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The SiC coatings deposited at substrate temperatures below 1100degreesC were found to be amorphous. Ex-situ, post deposition annealing in inert gas ambient above 1100degreesC converted the SiC films to a polycrystalline phase.