High-Rate Deposition of Amorphous SiC Films by Atmospheric Pressure Plasma Chemical Vapor Deposition (2nd Report)

Abstract

Using the atmospheric pressure plasma chemical vapor deposition (CVD) technique, further investigations were performed to improve the structure of the hydrogenated amorphous Si1-xCx(a-Si1-xCx:H) films deposited at extremely high rates. The films were prepared on Si(001) wafers at atmospheric pressure in a very high frequency (VHF) plasma of gas mixtures containing He, H2, SiH4 and CH4. Structure (C-H and Si-H bond densities) and composition of the a-Si1-xCx:H films were studied as functions of VHF power, CH4/SiH4 ratio and the substrate temperature by infrared (IR) absorption spectroscopy and Auger electron spectroscopy. Surface morphology of the films was observed by scanning electron microscope (SEM). It was implied that particles generated in gas phase deteriorated the film morphology and caused excessive incorporation of hydrogen atoms in the film. Both suppressing particle formation in gas phase and elimination of excessive hydrogen atoms bonded to C and Si atoms at the film-growing surface were important factors to enhance Si-C network formation. As a result of optimising the deposition parameters, a stoichiometric a-SiC:H film could be deposited at the substrate temperature of 550°C.