ケイ素を添加した酸窒化クロム薄膜の機械的特性とその微構造

Abstract

Cr-Si-N-O thin films were prepared by radio frequency reactive unbalanced magnetron sputtering. Compositional analysis of the thin films was carried out by Rutherford backscattering spectrometry and electron energy loss spectroscopy. It was found that these thin films contained approximately up to 11 mol% silicon. Film thicknesses were measured by using a scanning electron microscope; specimens had varying thicknesses from 200 nm to 2.5 μm arising from the changes in the locations of the samples and sputtering rates of targets. Phases in the samples were identified by X-ray diffraction. All samples showed only broad peaks based on NaCl-type-CrN. Diffraction peaks attributed to Cr2N, chromium oxides, and the silicon compounds were not observed. From the analysis of Fourier transform infrared spectroscopy, peaks attributed to the Cr-N bond of CrN, peaks attributed to the Si-O bond of SiO2 and peaks attributed to Si-N bond of Si3N4 were observed. There were no peaks attributed to chromium oxides. Microstructures were observed by transmission electron microscopy; grain size decreased with increasing silicon content. A nano-indentation method was used to measure indentation hardness and elastic modulus of the thin films. In accordance with a change of silicon content, the hardness increased up to a maximum value of 40 GPa and the elastic modulus was also increased from 185 to 215 GPa.