Ž . Diamond and Related Materials 9 2000 17901794 Chemical bonding, structure, and hardness of carbon nitride thin films W.T. Zheng a,b,d,  , W.X. Yu a , H.B. Li a , Y.M. Wang a , P.J. Cao b , Z.S. Jin b , E. Broitman c , J.-E. Sundgren c a Department of Materials Science, Jilin Uni  ersity, Changchun 130023, PR China b State Key Laboratory of Superhard Materials, Jilin Uni  ersity, Changchun 130023, PR China c Department of Physics, Linkoping Uni  ersity, S-581 83 Linkoping, Sweden d National Key Laboratory of Ion, Electron, Laser Modification, Da Lian Science and Technology Uni  ersity, Dalian 116024, PR China Abstract Ž . Carbon nitride films are deposited on Si 001 substrates by reactive d.c. magnetron sputtering graphite in a pure N discharge. 2 Ž . The chemical bonding and structure of carbon nitride films were probed using Fourier transformation infrared FTIR and near Ž . edge X-ray absorption fine structure NEXAFS , and the hardness was evaluated using nanoindentation experiments. The Ž . structure and hardness for the films are dependent on the substrate temperature T . FTIR and NEXAFS spectra show that N s atoms are bound to sp 1 , sp 2 and sp 3 hybridized C atoms, and the intensity of   resonance for C1s NEXAFS spectra is the lowest for the film grown at T 350°C, having a turbostratic-like structure, high hardness and stress. The correlation between the s structure and hardness of carbon nitride films is discussed.  2000 Elsevier Science S.A. All rights reserved. Keywords: Nitrides; Bonding; Structure; Hardness 1. Introduction Carbon nitride films have attracted the attention of various investigators due to their interesting character- istics and wide range of promising applications such as cutting tools, wear resistance, and a hard barrier against  corrosion 1 . Despite their technological importance, very few studies on the correlation between the struc- ture and mechanical properties of the CN materials have appeared in the literature. In previous papers, we reported on the effects of nitrogen partial pressure, Ž .   substrate temperature T 2 , substrate bias 3 and s  substrate materials 4 on the carbon nitride film depo- sition rate, nitrogen content, chemical bonding states of C and N atoms, and structure in the films. Among these growth parameters, substrate temperature has  Corresponding author. Ž . E-mail address: mat@mail.jlu.edu.cn W.T. Zheng . been identified to be the most important in determin-   ing the final film characteristics 2  5 . Therefore, in this study, we study the temperature dependence of the chemical bonding, structure and hardness of carbon nitride films deposited by d.c. magnetron sputtering. In particular, the correlation between the structure and mechanical properties of the films is investigated. 2. Experimental details Ž . Deposition of carbon nitride thin films on Si 001 substrates was carried out by d.c. magnetron sputtering with a base pressure of 1  10 6 Pa. The target was a high-purity 99.99% pyrolytic graphite disc, 75.6 mm in diameter by 3 mm thick, separated by 10 cm from the resistively heated substrate holder. The target was sput- ter-cleaned prior to deposition, with a shutter shielding Ž . the substrate from the depositing species. The Si 001 substrates were wafers with a resistivity of approxi- 0925-963500$ - see front matter  2000 Elsevier Science S.A. All rights reserved. Ž . PII: S 0 9 2 5 - 9 6 3 5 00 00314-9