Deposition of nanocomposite CNx/SiO2 films in inductively coupled r.f. discharge

Hard films were deposited in an inductively coupled r.f. discharge at a fre quency of 3.5 MHz by the chemical transport of carbon from a graphite targe t in a nitrogen atmosphere combined with evaporation from a quartz tube. Th e nitrogen flow was varied from 1.0 to 4.0 seem. The r.f. power supplied wa s in the range 2.5-3.5 kW. Silicon substrates were placed on the graphite h older whose temperature was 700-800 degrees C. In the emission spectra the CN, N-2 and C-2 molecular bands and the silicon, carbon, oxygen and nitroge n atomic lines were observed. The ratio of nitrogen to carbon in the films ranged from 0.1 to 0.55 while the ratio of oxygen to silicon was about 2 fo r all the films studied. The films had a maximum hardness of 35 GPa and the y showed a high elasticity up to 88%, good fracture toughness and adhesion to the substrate. Unlike carbon nitride films the CNx/SiO2 films were almos t non-absorbing in the visible range. (C) 2000 Elsevier Science S.A. All ri ghts reserved.