Surface roughness characterization of disks intended for extremely high density recording

For extremely-high-density recording using conventional technologies, the fly-height needs to decrease to less than 10 nm. Under such conditions, surface roughness becomes a critical factor in ensuring reliable operation of HDDs. A detailed surface roughness technique known as the Birmingham-14 set of parameters is used to characterize extremely smooth disks, which includes amplitude, spatial, hybrid, and functional aspects of the disk roughness. Also, the effects of lubricant thickness on roughness is investigated, and lastly two different disks with similar RMS roughness values are compared to determine which roughness parameters may be indicative of disk dynamic performance.