Carbon nitride (CNx) films had been grown on Si (0 0 1) substrates using rf magnetron sputtering method in pure N-2 as substrate bias (V-b) was varied from 0 V to - 150 V and substrate temperature (T-s) kept at a constant of 350 degreesC. The chemical bonding states of CNx films were characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was observed that a predominant formation of sp(3) C-N bonds occurred in carbon nitride films grown at bias of -50 V. The scratch test was utilized for measurement of CNx coating adhesion on Si (0 0 1). and then the morphology of the films was analyzed using atomic force microscopy (AFM) experiments. The results revealed that CNx films grown at V-b = -100 V, having the smoothest surface with the lowest rms roughness of 0.75 nm, adhered much more strongly to the Si (0 0 1) substrate than at other substrate bias values. Furthermore, the effect of ion bombarding on the adhesion and roughness of CNx films on Si (0 0 1) was discussed. (C) 2002 Elsevier Science B.V. All rights reserved.