Mechanical properties and corrosion studies of amorphous carbon on magnetic disks prepared by ECR plasma technique

Diamond-like carbon (DLC) films were prepared on magnetic disk surfaces usi ng an electron cyclotron resonance assisted microwave plasma chemical vapor deposition (ECR-MPCVD) system with variable radio-frequency (r.f.) substra te bias. Surface roughness of DLC deposited on hard disks was investigated by atomic force microscopy (AFM), which revealed that the DLC coated surfac es are smoother than those of the uncoated disks. Nitrogen incorporation in to the films (a-C:N) further reduced the root-mean-square (RR IS) roughness to 2.5 Angstrom for films prepared at a substrate bias of - 120 V. Scratch resistance was improved when the DLC coatings were deposited at bias volta ges greater than -90 V. However, the nitrogen introduction into the films d eteriorated their scratch resistance. When the DLC films were subjected to an accelerated corrosive environment, pinhole density remarkably varied wit h the deposition conditions. The DLC films deposited with lower substrate b iases and nitrogen incorporation resulted in poorer corrosion resistance. I nternal stress, hydrogen content and graphitic cluster size of these films were correlated with data acquired by Raman analysis. (C) 2000 Elsevier Sci ence S.A. All rights reserved.