Measurement of the elemental composition of a-SiC:H films by electron spectroscopy and high energy ion scattering spectrometry

Abstract

Amorphous hydrogenated silicon carbide (a-SiC:H) thin films were deposited at low (175 °C) and medium (600 °C) temperatures using plasma enhanced chemical vapor deposition. By variation of the precursor gases, a broad range of film stoichiometry was obtained. The a-SiC:H films were characterized by electron spectroscopy [x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES)], high energy ion scattering spectrometry [Rutherford backscattering spectrometry (RBS), elastic recoil detection], and ellipsometry. Quantitation of the carbon to silicon ratio was performed using elemental sensitivity factors in electron spectroscopy and compared with the inherently quantitative values obtained by RBS. The discrepancy between XPS and RBS was 5%–10%. The discrepancy between AES and RBS was significantly worse, but could be reduced to the same range as XPS with the use of an appropriate standard material. It was observed that ion beams typically used in sputter depth profiling did not result in significant preferential sputtering in the a-SiC:H films, but those used in ion scattering measurements can modify films with large hydrogen concentrations. Calculations of film thickness from the ion scattering data showed excellent agreement with results obtained from ellipsometry.