Ultrasmooth CNx overcoats for next-generation hard disks

De Jun Li*, Yip Wah Chung

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Ultrathin carbon nitride (CNx) overcoats were grown using pulsed dc magnetron sputtering. Substrates were mounted on a holder that allowed 45° tilt angle and rotation at different speeds. Effects of sputter gas composition, target power, substrate bias, substrate tilt, and rotation on film growth and properties were explored. Atomic force microscopy scans over large sampling areas show that thin CNx films obtained at -100 V substrate bias with 45° substrate tilt and 20 r/min rotation have root-mean-square roughness almost four times lower than those prepared without substrate tilt and rotation. Several percent of helium in an Ar-5%N2 sputter gas was found to improve surface roughness of these coatings. These 1-nm-thick ultrasmooth coatings reduced corrosion damage compared with coatings of the same thickness grown without substrate tilt and rotation. This improved performance appears to be directly related to the growth of smoother and denser coatings synthesized under the present conditions.

Original languageEnglish (US)
Pages (from-to)765-768
Number of pages4
JournalIeee Transactions on Magnetics
Issue number2 I
StatePublished - Mar 2003


  • Coatings
  • Corrosion
  • Hard disks
  • Sputtering

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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