STRUCTURAL, MECHANICAL AND TRIBOLOGICAL PROPERTIES OF PLASMA-ASSISTED CHEMICALLY VAPOR-DEPOSITED HYDROGENATED CXN1-X-H FILMS

Amorphous hydrogenated carbon nitride (a-CxN1-x:H) films were prepared at low deposition temperatures (below 150 degrees C) using a capacitively coupled r.f. plasma-assisted chemical vapour deposition process starting from CH4-N-2 gas mixtures. Films were deposited on glass, Si and steel substrates which were placed on the powered and grounded electrodes. The chemical composition of the films was analysed with electron probe microanalysis. By varying the CK4:N-2 partial pressure ratio, the N content of the films could be varied between 0 and 13 at.% at the powered electrode and between 0 and 35 at.% at the grounded electrode. Nanoindentation hardness measurements, film stress (bending beam test method) and wear measurements (against a steel ball in the ball-on-disc test) on films deposited at the powered electrode demonstrate that nitrogenation of amorphous carbon films leads to softer and less stressed materials. These results are explained in terms of the microstructural properties of our films which, according to our IR absorption spectroscopy and Raman spectroscopy measurements, can be interpreted on the basis of a familiar a-C:H cluster model.