MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF A-B1-XNX-H FILMS PREPARED BY RF PACVD

Amorphous B1-xNx:H films were prepared in a capacitively coupled r.f. plasma-assisted chemical vapour deposition reactor at deposition temperatures below 200 degrees C starting from N-2-B2H6 (10% in H-2) gas mixtures. Films were deposited on Si, steel and glass substrates which were placed on the grounded and powered electrodes. By varying the partial pressures of the gases, the composition parameter x was varied between 0 and 0.55. Optical emission spectroscopy was used to monitor H-, B-and N-related plasma species. The film microstructure was characterized by IR spectroscopy in the wavenumber range 400-4000 cm(-1) Compressive film stress (bending beam method) and hardness (nanoindentation method) were measured as a function of composition and bias voltage. Wear and friction behaviours were studied under humid and dry N-2 ambient conditions using a ball-on-disc apparatus. A comparison between a-B:H films and a-C:H (diamond-like carbon) films reveals similar mechanical properties but a very different wear behaviour. This result is explained in terms of different friction mechanisms related to the formation of transfer layers.