Mechanical and optical properties of hard SiCN coatings prepared by PECVD

Amorphous Si/C/N:H where synthesized by plasma enhanced chemical vapor deposition (PE-CVD) using the single-source precursors hexamethyldisilazane (HMDS) and bis(trimethylsilyl)carbodiimide (BTSC). The films produced using the HMDS precursor were rich in carbon, while the films synthesized from the BTSC precursor were high in nitrogen content. All films were amorphous and exhibited a similar hardness to SiC or Si 3 N 4 . Fundamental properties of the films were determined in tests such as ultra micro-hardness, elastic modulus, thickness and adhesion. To investigate the composition of the films, composition depth profiles were determined by GDOES. The wear behaviour was studied in sliding tests under oscillating motion. To investigate the wear mechanisms, the wear tracks were examined with topographical analysis, REM as well as EDX.

Development of PE-CVD Si/C/N:H films for tribological and corrosive complex-load conditions

Thin films of amorphous silicon carbide nitride (a-SiC x N y ) were deposited in a rf magnetron sputtering system using a SiC target. Films with various compositions were deposited on to silicon substrate by changing the N 2 /Ar gas ratios during sputtering. Nano-indentation studies were performed to investigate the mechanical properties of the SiCN films. Surface morphology of the films was characterized by using Atomic Force Microscope. X-ray Photoelectron Spectroscopy (XPS) data indicated that the chemical status is highly sensitive to the nitrogen ratios during sputtering.

Investigations on hardness of rf sputter deposited SiCN thin films

Amorphous silicon carbon nitride (Si/C/N) coatings were prepared on steel substrates by RF plasma-enhanced chemical vapour deposition (RF-PECVD) from the single-source 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 on the RF-powered electrode (cathode) were black, thick (>20 μm) and hard (21–29 GPa), while those grown on the grounded electrode (anode) were yellow, thin (<4 μm) and soft (∼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 μm × 5 μm. 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.

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

J. Alizadeh

Papers

Deposition and optical studies of silicon carbide nitride thin films