Characterization of hydrogenated amorphous Si1-xCx films prepared at extremely high rates using very high frequency plasma at atmospheric pressure

Using the atmospheric pressure plasma chemical vapour deposition (CVD) technique, hydrogenated amorphous Si1-xCx(a-Si1-xCx : H) films were deposited at extremely high deposition rates. The films were prepared on Si(001) wafers at atmospheric pressure in a very high frequency (150 MHz) plasma of gas mixtures containing He, H2, SiH4 and CH4. Film properties (structure, density and composition of a-Si1-xCx : H) were studied as functions of CH4 concentration and substrate temperature by transmission electron microscopy, Auger electron spectroscopy and infrared (IR) absorption spectroscopy. The relation between IR absorption spectra and chemical resistance of the films to 15% KOH solution was also investigated. The maximum deposition rate was 50 nm s-1, which was more than ten times faster than that achieved by the conventional plasma CVD technique. It was found that when the CH4 concentration was more than ten times higher than SiH4, the interaction of CH4 with SiH4 was saturated, and carbon-rich a-Si1-xCx : H films were formed. The density of the a-Si1-xCx : H films was about 1.5 g cm-3, being less than half of the crystalline value of SiC. The a-Si1-xCx : H film was not etched by a KOH solution, which was supported by IR analysis of the Si-C stretching vibration mode