Effect of annealing on the composition, structure and mechanical properties of carbon nitride films deposited by middle-frequency magnetron sputtering

Carbon nitride films were deposited by middle-frequency reactive magnetron sputtering and annealed at different temperatures in nitrogen ambient. X-ray photoelectron spectroscopy, Raman scattering, transmission electron microscopy, and nano-indenter were used to characterize the as-deposited and annealed films. The analysis showed that annealing resulted in the dissociation of N and C in the films. The dissociation of C happened after 500 degrees C and lagged behind that of N. With the increase of annealing temperature, the disorder of sp(2) C decreased and the films were gradually graphitized. The microstructure changed from amorphous to fullerene-like CNx with the annealing temperature increasing to 500 degrees C, and then to nitridized graphite nanocrystals at 600 degrees C. The graphitization resulted in a drastic decreasing of hardness and modulus of the films. (C) 2006 Elsevier B.V. All rights reserved.