AVS 49th International Symposium
    Thin Films Thursday Sessions
       Session TF-ThA

Paper TF-ThA8
Synthesis of Ultrasmooth CN@sub x@ Overcoats for 1 Tb/in@super 2@ Magnetic Storage Applications

Thursday, November 7, 2002, 4:20 pm, Room C-101

Session: Ultra Thin Films
Presenter: D.-J. Li, Northwestern University
Authors: D.-J. Li, Northwestern University
Y.-W. Chung, Northwestern University
Correspondent: Click to Email
Nitrogenated carbon (CN@sub x@) is now being used in protective overcoats of commercial hard disk systems, due to its compatibility with existing lubricants as well as desirable tribological and corrosion protection performance. The current goal of the disk drive industry is to increase the areal storage density to 1 Tb/in@super 2@ by reducing the head-disk spacing. Modeling calculations show that the protective overcoat thickness has to reduce from 4-5 nm in current dirves to 1.0 nm. In this case, producing an atomically smooth and dense CN@sub x@ coating with low defect density becomes crucial. The purpose of this work is to synthesize smooth and pinhole-free CN@sub x@ overcoats over large areas by controlling magnetron sputtering process parameters. Effects of sputter gas composition, target power, substrate bias, substrate tilt and rotation speed on film growth and properties were explored. One important finding from this study is the combined use of substrate tilt and rotation. AFM scans over large sampling areas show that thin CN@sub x@ films obtained at -100 V substrate bias with 45 degree substrate tilt and 20 rpm rotation have r.m.s roughness almost four times lower than those prepared without substrate tilt and rotation. These 1-nm thick ultrasmooth coatings reduced corrosion damage by a factor four compared with coatings of the same thickness grown without substrate tilt and rotation. This improved performance is likely a result of more efficient and uniform momentum transfer from energetic species in the plasma to surface atoms parallel to the surface during deposition in this configuration.