Preparation of boron carbide thin films from reactive sputtering of boron

Boron carbide thin films were prepared by RF magnetron sputtering. The films were deposited onto CoCr/Cr/SiO2/Si(100) substrates with an RF power of 25, 50 and 75 W in the range of 200 degreesC. The reactive gas was introduced up to 1.5 vol% (CH4/(Ar + CH4)) during deposition, and the resulting composition of the films matched these ratios, as observed by Auger electron spectroscopy. In X-ray photoelectron spectroscopy, two well-resolved peaks in C (Is) spectra were observed around 284 eV, indicating C-C bond at 284.5 eV and B-C bond at 283.5 eV. The X-ray diffraction of these films revealed the amorphous or nanocrystalline characteristics. At the deposition conditions of 75 W, 100 degreesC and 1.0 vol%, the nanoindented films were hardened to 16 GPa and the scratched surfaces endured load of 50 N. In the wear test, the coefficient of friction was also measured down to 0.15. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.