Perpendicular Media Overcoat Coverage Challenge

The perpendicular media investigated employed silicon oxide in the recording layer to facilitate grain segregation, as reported. Overcoat used for these studies includes sputtered CNx, SiNx and ion beam carbon. Method for corrosion assessment includes (1) ICP-MS measurement of extractable Co, (2) Electrochemical polarization curve, and (3) Temperature and Relative Humidity (T&RH) condensation test. Roughness-induced challenges on subsequent post processing steps is reported. Because PMR media is reported to have high surface roughness, our first study has been designed to quantify overcoat coverage limit and compare that with longitudinal media.