Mechanical properties of d.c. magnetron-sputtered and pulsed vacuum arc deposited ultra-thin nitrogenated carbon coatings

Nitrogenated carbon coatings (CNx) are widely used as protective coatings o n magnetic hard disks. In this paper, the mechanical properties of such coa tings produced with d.c, magnetron-sputtering and filtered high-current vac uum arcs (KCA) are compared, An AFM-based scratching technique has been use d that allows the generation and characterization of scratches with residua l depths in the Angstrom range. With this technique, the very beginning of plastic deformation and the scratching resistance of ultra-thin coatings (5 nm) can be investigated. The scratching resistance of different sets of fi lms was compared to Raman spectra, X-ray photoelectron spectroscopy (XPS) a nd surface acoustic wave (SAW) measurements. For samples with a higher resi stance against mechanical penetration on a sub-nanometer scale, a higher Yo ung's modulus and a downshift of the Raman G and 700 cm(-1) peak position w as observed. It turned out that for magnetron-sputtered films, the resistan ce against mechanical penetration increases with higher nitrogenation, wher eas the films produced by HCA show an inverse tendency. The scratching resi stance and the Young's modulus of HCA films decrease nearly linearly with i ncreased deposition temperature. (C) 2001 Elsevier Science B.V. All rights reserved.