Micromechanical investigations of amorphous hydrogenated carbon films on silicon

Abstract

Amorphous hydrogen containing carbon films (α-C:H) can be obtained on various substrates by exposure to an rf-glow discharge in a low pressure hydrocarbon atmosphere. The films show interesting optical and mechanical properties and are thus attractive candidates for hard and wear resistant coatings. In this paper results of microhardness measurements on thin (0.8 μm) α-C:H films are presented which were taken with a specially designed microhardness tester which allows indentation depth as low as 50 nm. In this way the influence of the substrate on the hardness results can be minimized. A large influence of the film deposition parameters was found. The hardness of films deposited under high dc bias voltage (>1000 V) is comparable to or better than that of bulk silicon. Heat treatment of the films above 350 °C decreases the hardness significantly. The elastic properties of α-C:H may be estimated using the elastic relaxation of the indents.