Investigation of Substrate Surface Morphology Effects on Media Performance

An advanced perpendicular magnetic recording (PMR) media requires continuous improvements in substrate surface morphology and defects counts in order to lower the fly height of a read/write head, reduce the yield loss related media defects, and improve the magnetic performance. A PMR media texturing process is a process used to remove asperities to generate a smoother and better quality surface without leaving circumferential textured patterns on the surface. We have developed a glass substrate mechanical texturing process, E process, using a fine texturing tape with a fiber size of 0.35 μm and small nano-cluster diamond (NCD) abrasive particles with a size of 12 nm. The E process produces a lower surface roughness Ra (from 0.21 to 0.06 nm) and results in the lowest glide avalanche (from 6.35 to 2.54 nm). These results indicate that a better quality media with low-defectivity can be obtained using the new developed mechanical texturing process. This process generates a very smooth surface with few textured scratches and adequate textured removal amount. A smoother substrate with a lower Ra leads to a narrower dispersion of rocking angle, Δθ50 of Co(0001), and half width of transition, TW50, and therefore resulting in improvements of OW and SNR.