Properties of sputter-deposited hydrogenated carbon films as a tribological overcoat used in rigid magnetic disks

Abstract The physical and mechanical properties of hydrogenated carbon (H-C) films used in rigid magnetic disks were studied using various techniques. The H-C films were fabricated on 65 mm Al/NiP substrates using d.c. magnetron sputtering and a mixture of argon and hydrocarbon gases. The hydrogen concentration in the H-C layer, which was analyzed by hydrogen forward scattering, ranges from 4 to 28 at. %. The structure of the H-C films was studied by Raman spectroscopy. Raman analysis indicates that the H-C films with a higher hydrogen concentration show a down-shift of the G-band peak and a decrease in the ratio of the integrated intensity of the D band to that of the G band. From the measurement of electrical resistance, it was found that an increased hydrogen concentration in the H-C films increases the electrical resistance of the film. For the mechanical properties of the H-C films, the nanohardness and elastic modulus of H-C films 350thick were measured. The nanohardness and elastic modulus of thin H-C films obtained from the load and displacement curves were found to be strongly affected by the hydrogen concentration in the films. These physical and mechanical properties of H-C films deposited by sputtering are compared with those of thin films obtained by plasma-enhanced chemical vapor deposition techniques. These physical and mechanical properties of H-C films obtained from the sputtering process could provide excellent wear resistance in magnetic disk applications.