Hard silicon carbonitride films obtained by RF-plasma-enhanced chemical vapour deposition using the single-source precursor bis(trimethylsilyl)carbodiimide

Amorphous silicon carbon nitride (Si/C/N) coatings were prepared oil steel substrates by RF plasma-enhanced chemical vapour deposition (RF-PECVD) from the single-SOLH-Cc precursor bis(trimethylsilyl)carbodiimide (BTSC). The films were characterised by X-ray diffraction (XRD), ellipsometry, FTIR, glow discharge optical emission spectroscopy (GDOES), optical microscopy, AFM, hardness measurements, scratch-, tribological- and corrosion-tests. The results of these studies show that the coatings obtained oil the RF-powered electrode (cathode) were black, thick (> 20 mu m) and hard (21-29 GPa), while those grown oil the grounded electrode (anode) were yellow, thin (< 4 mu m) and soft (similar to 5 GPa). Coatings on the anode contained around 19 at.% oxygen and exhibited silicon predominantly bonded to oxygen. In contrast, the oxygen content of the films deposited on the cathode was below 2 at.%. Silicon atoms in these coatings are co-ordinated predominantly to nitrogen and carbon. The surface Of all coatings was very smooth with a maximum rms roughness between 2 nm and 5 nm for an area of 5 mu m x 5 mu m. Scratch and tribological tests reveal a brittle nature of the cathode-coatings and rather weak adhesion to the metal substrates. Salt-spray tests indicate an excellent corrosion resistance of the material. (c) 2005 Elsevier Ltd. All rights reserved.