AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI-FrM

Paper MI-FrM3
Interface Reactions between Quaternary Cobalt Alloys and Carbon Overcoats in Thin Film Disk Media

Friday, October 6, 2000, 9:00 am, Room 206

Session: Magnetic Recording: Media and Heads
Presenter: J.-U. Thiele, IBM Storage Technology Division
Authors: J.-U. Thiele, IBM Storage Technology Division
D.J. Pocker, IBM Storage Technology Division
R.L. White, IBM Storage Technology Division
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In the magnetic disk drive industry's quest for ever higher data storage areal densities, the head-to-disk spacing and consequently the film thicknesses of all functional layers of magnetic media continue to decrease. In the future the thicknesses of magnetic storage layers and carbon overcoat can be expected to approach the typical thicknesses of chemical interface reactions, i.e. thicknesses of the order of a few nanometers. Here we present a core level X-ray photoelectron spectroscopy study of interface reactions between CoPtCrB and CoPtCrTa magnetic alloy layers and 35 Å thick protective hydrogenated and nitrogenated carbon overcoats on metal hard disks. In comparing CoPtCrTa alloy films with a nitrogenated carbon overcoat to the same media with hydrogenated carbon overcoats we find a drop in coercivity of up to 200 Oe. The formation of tantalum nitride as well as small amounts of chromium nitride was detected in the photoelectron spectra. Conversely, spectra of nitrogenated carbon films on B-containing alloys showed the formation of boron nitride and small amounts of chromium nitride at the interface. The amount of boron nitride varies depending on substrate bias voltage and temperature. Surprisingly, no effects of these interface reactions on the magnetic properties of the disks could be detected. In summary, while the formation of boron nitride at the interface of CoPtCrB media and protective carbon overcoat does not affect the magnetic properties of the disks in the range of boron and nitrogen concentrations investigated here, small changes in the chemical environment of Ta and/or Cr can lead to significant changes in the magnetic properties of the CoPtCrTa media.