AlN: A Hexagonal-Nitride Seed Layer Underneath Ru for Granular-Type Perpendicular Magnetic Recording Media

A new hexagonal-nitride material, AlN, is proposed in place of current metallic materials as a seed layer underneath the Ru layer for perpendicular recording media. It was found that (1) c-plane oriented AlN with wurtzite structure can be realized by direct current reactive sputtering, (2) c axis direction distribution (FWHM) of AlN decreases with the change in buffer structure from nano-crystalline to amorphous, which also results in reduction of the FWHM of Ru, (3) a Ru layer with low averaged grAlN size less than 8.0 nm retAlNs low FWHM at less than 4.0 degrees, and surface roughness with peak to valley of 2.0 nm is available by insertion of the AlN seed layer, (4) for substrate/FeCoB buffer (10 nm)/AlN/Ru/CoPtCr-SiO2 (16 nm) media, an increase in the thickness of the AlN layer is also effective for magnetic isolation of granular-type media, in addition to a decrease in the Ru layer thickness, which means that the AlN layer can substitute a part of the Ru layer.