Boron carbon nitride (BCxNy) films were deposited on silicon wafers by RF magnetron sputtering of boron and graphite targets. BCN films with different compositions were obtained by varying the sputtering power of the graphite target (60, 180, 240 W). Chemical bonding states, composition and structure of the films were investigated by FTIR, XPS and AES analysis. The BCN films synthesized in this work were found to be B-C-N hybridized amorphous material, whose microstructure was examined with TEM observation. Mechanical properties of BCN films were compared to find the effect of the carbon sputtering power and resultant compositional changes on this ternary system. A BCN film with hardness of 15 GPa was synthesized at the high power of carbon source. With a higher sputtering power of carbon, hardness, elastic modulus and friction coefficients of a BCN film were increased due to the increase of strong B-C, C-C and C-N bonds in the amorphous BCN film. (C) 2003 Elsevier B.V. All rights reserved.