Characterization of Head Overcoat for 1 Tb/in $^{2}$ Magnetic Recording

To achieve a 1 Tb/in² system, diamond-like carbon (DLC) on head and disk have to meet the criteria of corrosion- and wear-resistance at thicknesses of less than 2 nm. This paper will assess the performance of head and disk overcoat for a 1 Tb/in² system and beyond, with focus on the influence of DLC forming technologies, thickness, and substrate materials. To evaluate DLC film, sp³ fraction was measured by X-ray photoelectron spectroscopy (XPS). It was shown that DLC films fabricated by filtered cathodic vacuum arc (FCVA) would have less sp³ fraction with decreasing thickness. To evaluate corrosion- and wear-resistance, coverage and critical loads were measured by XPS and atomic force microscopy scratch test. XPS revealed that DLC films prepared by both FCVA and ion-assisted sputtering had sufficient coverage at thickness of down to 1 nm. Atomic force microscopy scratch test showed that critical load depends on substrate materials and DLC thickness, not on DLC forming methods.