Surface characterization of Co/CNx granular films fabricated by nanolamination

Cobalt-carbon thin films proposed for use as granular magnetic media are ge nerally prepared by co-deposition sputtering. An alternative method is nano lamination of the component layers (media and matrix) followed by annealing , We have produced and characterized thin-film granular structures prepared from nanolaminate layers of Co and CNx. For the as-deposited samples, only metallic cobalt is observed with XPS and a constant nitrogen concentration x similar to 0.15 was measured for the carbon nitride layers. The annealed films have oxidized cobalt in the very near surface region. Atomic force m icroscopy measurements show that the surface of the film roughens significa ntly upon annealing, with the RMS roughness increasing from 0.2 to 1.0 nm. Thus, it appears that the nanostructural evolution caused by the annealing process, which gives rise to grain formation, also degrades the smooth surf ace of the CNx capping layer and exposes some of the cobalt to ambient. The potential implications of these observations on tribological performance a re explored. Copyright (C) 2000 John Wiley & Sons, Ltd.