Ultrathin carbon overcoats: processing, characterization and tribological performance

The thickness of carbon overcoats has been reduced to 30 Å or less to achieve high areal density in magnetic media. Presently, technologies such as ion beam deposition and plasma enhanced chemical vapor deposition (PECVD) produce thin carbon overcoats with a high fraction of sp³ bonding. These hard and dense overcoats exhibit good wear durability and corrosion resistance. This paper discusses processing, characterization, and tribological and corrosion performance of ultrathin overcoats (30 Å or less) produced by PECVD. The physical and chemical properties of the carbon overcoat affect the carbon-lubricant bonding, which subsequently determines the head-disk interaction. Since optimal properties of the carbon vary at the lubricant and magnetic layer interfaces, an interfacial functionality approach is needed for the design of thin overcoats. Functionalized carbon overcoat is a design that consists of a PECVD carbon layer with a sputtered functional layer on top. Characterization and tribological performance and comparison of functionalized carbon overcoat with PECVD carbon is also presented.