Ultrathin CNx Overcoats for 1 Tb/in2 Hard Disk Drive Systems

Carbon nitride films were grown on silicon and hard disk substrates using pulsed dc magnetron sputtering in a single cathode deposition system. Substrates were mounted on a specially designed rotating holder that allowed 45° tilt angle and substrate rotation about the surface normal up to 20 rpm. AFM scans over 10×10 μm2 showed that 50 nm thick CNx films prepared under optimum substrate bias conditions have r.m.s. surface roughness almost four times lower than those prepared without substrate tilt and rotation. We observed a two-fold reduction in corrosion damage for hard disk substrates with 1 nm CNx overcoats deposited with substrate tilt and rotation. This improved performance is likely a result of more efficient and uniform momentum transfer parallel to the surface during deposition in this configuration.