Diamond-like carbon coatings applied to hard disks

Amorphous carbon (a-C:H) films were prepared on the surface of magnetic disks using an electron cyclotron resonance assisted microwave plasma chemical vapour deposition (ECR-MPCVD) system with variable radio-frequency substrate bias voltage. As indicated by the atomic force microscopy measurements, the surfaces of the hard disks coated with 10 nm thick films were smoother than those of the uncoated disks. The scratch resistance of coated disks increased at biases greater than -90 V. Corrosion resistance of the coatings was also studied by exposure to vapour of hydrochloric acid (HCl) for 24 h. The analysis showed that the radio-frequency bias voltage was a critical parameter affecting the chemical compositions, mechanical properties and corrosion resistance of the films. (C) 2000 Elsevier Science S.A. All rights reserved.