Thin films of silicon carbide nitride (SiCxNy) were deposited in an r.f. magnetron sputtering system using a SiC target. Films of different compositions were deposited by varying the ratios of argon and nitrogen in the sputtering ambient. X-ray photoelectron spectroscopy and atomic force microscopy studies on the deposited films indicated that the chemical states as well as the surface roughness are highly sensitive to the nitrogen ratios during sputtering.