Novel hybrid facing targets sputtered amorphous carbon overcoat for ultra-high density hard disk media

Amorphous carbon films form a critical protective layer on magnetic hard disk media. A novel in-house configured hybrid facing targets sputtering (HyFTS) utilizing a special magnetron arrangement was used to deposit amorphous carbon (a-C) overcoats. The corrosion inhibition ability and mechanical property were investigated and compared with that of the a-C overcoats deposited by conventional magnetron sputtering (CMS). Studies were done using electrochemical techniques and nano-scratch analysis to determine how corrosion inhibition ability changes at thickness of 2 nm and 5 nm and the scratch resistance of the two types of a-C overcoats, respectively. Electrochemical impedance spectroscopy and potentiodynamic polarization investigations have shown that a-C films deposited by HyFTS have good corrosion resistance even at 2 nm thickness. But at 2 nm, CMS deposited a-C overcoat shows sign of corrosion. Nano-scratch test has also shown improved scratch resistance of the HyFTS deposited a-C. This may be attributed to the better quality film with higher sp3 content deposited by HyFTS as a result of it having a higher amount of ionized species generated.