COMPARISON OF OXIDATION RATES FOR A-SI1-XCX-H FILMS DEPOSITED FROM PULSED AND CONTINUOUS-WAVE RF PLASMAS

Oxidation rates for hydrogenated amorphous silicon carbide (a-Si1-xCx: H) films deposited from both pulsed and continuous wave (CW) SiH4/CH4 rf (13.56 MHz) plasmas have been measured using Fourier transform infr ared spectroscopy. Films deposited from CW plasmas oxidize much more r apidly than those deposited from equivalently powered pulsed plasmas. The effect of a diluent gas in the feed (He, Ar, or H-2) on film oxida tion rates has also been investigated With He and Ar, the CW films oxi dize faster than the pulsed films. With H-2 as the diluent, however, t he CW films do not oxidize as rapidly as other CW films, even after lo ng periods of time. This is most likely the result of hydrogen radical s annealing the films through reactions with active sites on the CW fi lms. Addition of H-2 also decreases the deposition rates in both pulse d and CW systems, suggesting H-2 contributes to the deposition reactio n scheme. Additional compositional changes in the a-Si1-xCx:H material s with addition of H-2 to the plasma feed gas are also discussed.