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1 CNRS-LEMD, 25 Rue des Martyrs, 380042 Grenoble cedex 9, France
2 Belarussian State University, Pr.F. Scoriny 4, 220080 Minsk, Belarus
3 Institute for Superhard Materials, 2 Avtozavodskaya Street, 07074 Kiev, Ukraine
| Pure copper and copper-carbon composite films have been deposited on silicon substrates by sputtering of a copper target associated with microwave plasma-enhanced chemical vapor deposition process of carbon from argon-methane mixtures of various compositions. The composition of films was determined by Rutherford backscattering spectroscopy (RBS) and Raman spectroscopy. The morphology of the surface and cross-section of samples was examined by scanning electron microscopy. The crystallographic structure was identified by x-ray diffraction techniques. The electrical resistivity of films was obtained by four point probe measurements. These composite films consisted of polycrystalline copper and amorphous carbon phase. The copper crystallite size was in the range 15-30 nm and less than 5 nm for a carbon content in Cu-C films ranging from 20 to 25 at. % and from 60 to 75 at. %, respectively. The electrical resistivity of Cu-C films containing 20 to 25 at. % of carbon was approximately 2.5 μΩ cm whereas the resistivity value can reach 107 μΩ cm for films containing 60 to 75 at. % of carbon. A large variation of grain size and electrical resistivity of nanostructured Cu-C composite thin films was noticed as the CH4 concentration in the gas phase was varied from 60 to 70 %. The hardness and Young modulus of films were deduced from nanoindentation measurements. The friction coefficient of films was determined by pin- on-disk tribological tests conducted under various conditions. The deposition rate, composition, morphology, structure, electrical resistivity, mechanical properties and friction properties of films were investigated as functions of the methane concentration in the gas phase or carbon content in the Cu-C composite films. |
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