PRECURSOR GAS EFFECT ON THE STRUCTURE AND PROPERTIES OF DIAMOND-LIKE CARBON-FILMS

The effect of precursor gases on the diamond-like carbon (DLC) film de position was investigated in the r.f. plasma-assisted CVD method. DLC films were deposited using methane or benzene as the precursor gas. Th e residual stresses, hardnesses, total hydrogen concentrations and ele ctron energy loss spectra were compared at the same value of V(b)/P1/2 . (Here, V(b) is the self-bias voltage of cathode and P the deposition pressure.) The values of V(b)/P1/2 ranges from 33 to 250 V mTorr-1/2 for methane and from 33 to 900 V mTorr-1/2 for benzene by changing the negative bias voltage from -100 to -900 V and deposition pressure fro m 1 to 100 mTorr. We observed significant differences between the stru ctures and properties of these films. In the same range of V(b)/P1/2 t he structure and properties of films deposited from benzene show chara cteristic behaviors of lower energy deposition than those from methane . The present observations are discussed in terms of the difference in the ion energy per carbon atom at the growth surface. The total hydro gen concentration in the films deposited from benzene is smaller by ab out 7 at.% in this experimental range.