Local structural analysis of a-SiC x:H films formed by decomposition of tetramethylsilane in microwave discharge flow of Ar

Abstract

Hydrogenated amorphous silicon carbide ( a-SiC x :H) films were prepared by the decomposition of tetramethylsilane (TMS) with microwave discharge flow of Ar. When radio-frequency (RF) bias voltage (− V RF) was applied to the substrate, the film hardness increased as (2.39 ± 1.12)–(9.15 ± 0.55) GPa for − V RF = 0–100 V. The a-SiC x :H films prepared under various − V RF conditions were analyzed by the carbon-K near edge X-ray absorption fine structure (NEXAFS), by the elastic recoil detection analysis (ERDA), and by the X-ray photoelectron spectroscopy (XPS). From a quantitative analysis of NEXAFS, the sp 2/(sp 2+ sp 3) ratios of C atoms were evaluated as 67.9 ± 2.0, 55.4 ± 2.7, and 51.7 ± 0.7% for − V RF = 0, 60, and 100 V, respectively. From ERDA, hydrogen content of the film prepared under the condition of − V RF = 100 V was found to decrease 28% comparing with that under − V RF = 0 V. It is suggested that the cause of the increase of the film hardness when applying − V RF is predominantly the growth of the sp 3-hybridized structure of C atoms accompanied by the decrease of hydrogen terminations.