DEPOSITION AND CHARACTERIZATION OF THIN BORON-CARBIDE COATINGS

Thin boron-carbide films were deposited using a PACVD process on Si substrates at room temperature. Various mixtures of B2H6/He and CH4, as well as the less hazardous B(CH3)3, have been used as process gases. The composition of the deposited films has been correlated with the B2H6/He/CH4 mixture used. When using B(CH3)3, the coatings were found to be slightly boron enriched compared to the gas phase stoichiometry. In both cases oxygen contaminants were additionally found (up to 5 at %) in the films. Most of the oxygen was incorporated from the residual gas at the beginning of the deposition. The coatings were hard and showed good adherence to the substrate; no film peel-off was observed after exposure to air. The films have been characterized, in-situ, by electron spectroscopy (XPS, UPS, AES), and by other methods (AES depth profiling, SEM, alpha-step).