Near edge X-ray absorption fine structure study for optimization of hard diamond-like carbon film formation with Ar cluster ion beam

Diamond-like carbon (DLC) film deposited using C60 vapor with simultaneous irradiation of an Ar cluster ion beam was characterized by a near edge X-ray absorption fine structure (NEXAFS), in order to optimize the hard DLC film deposition conditions. Contents of sp2 orbitals in the films, which were estimated from NEXAFS spectra, are 30% lower than that of a conventional DLC film deposited by a RF plasma method. Those contents were obtained under the flux ratio of the C60 molecules to the Ar cluster ions to range from 1 to 20, at 5keV of Ar cluster ion acceleration energy. Average hardness of the films was 50 GPa under these flux ratios. This hardness was three times higher than that of a conventional DLC film. Furthermore, the lowest sp2 content and above-mentioned high hardness were obtained at room temperature of the substrate when the depositions were performed in the range of the substrate temperature from room temperature to 250degC. (author)