Fabrication of magnetic nanodot array using electrochemical deposition processes

We investigated fabrication processes of magnetic nanodot arrays for the ultra-high density magnetic recording media by using an electrodeposition. A CoZrNb underlayer was sputter-deposited on a glass disk substrate as a soft magnetic underlayer (SUL). Nano-patterns were formed on the substrate by UV-nanoimprint lithography (UV-NIL) and CoPt was electrodeposited into the nano-patterns. For obtaining uniform CoPt nanodot arrays with high perpendicular coercivities, we applied thin Cu intermediate layer on CoZrNb SUL and minimized its thickness. As a result, we obtained CoPt nanodot arrays with 150-nm diameter, 300-nm pitches, and 20-nm heights, which have uniform structures, on the substrates with the construction of Cu (1-2 nm)/CoZrNb (100 nm)/Cr (5 nm)/glass disk. The perpendicular coercivity of the CoPt nanodot arrays was as high as 5.4 kOe. From these results, we showed that the Cu intermediate layer with even 1-2 nm thick considerably improved the deposition condition on the substrates with CoZrNb SUL to successfully fabricate CoPt nanodot arrays with the diameter and pitches of 80 nm and 160 nm with sufficient uniformity.