This study uses the Taguchi method and Grey relational analysis in order to simultaneously improve the magnetic and corrosion performance in media. Higher resistivity and Co corrosion resistance of the overcoat film were found using higher source gas H/C ratio and gas flows. This trend is due to the fact that the Id/Ig ratio decreases with increasing source gas H/C ratio and flowrate, which indicate a compositional change from a less dominant sp3 structure towards a highly dominant sp3 structure. The optimal diamond-like carbon (DLC) deposition parameters are source gas C2H6, bias voltage of −100 V, anode voltage of 100 V and gas flow of 40 sccm. Compared with the standard DLC deposition conditions, this improved process result obtained from the optimisation of overcoat deposition parameters can achieve a 0·5 nm lower overcoat thickness with excellent corrosion resistance and a 0·90 dB higher SpSNR.
