Nano-patterned Medium Fabricated by the Artificially Aligned Self-Assembling Method

Abstract

A new method for fabricating a patterned magnetic recording medium is presented. This method uses the self-assembling phenomenon of the diblock copolymer. A tetragonal array of ordered polymer dots is aligned by a circumferential groove pattern on a disk substrate. The groove pattern is transferred from a Ni master plate by a nanoimprinting process. CoCrPt patterned media with a dot pattern were fabricated using this method (artificially aligned self-assembling (AASA) method). The dot size was about 40 nm in diameter. Magnetic estimations showed the single-domain CoCrPt dots with good magnetic isolation. The patterned medium showed a perpendicular magnetic orientation induced by the crystalline anisotropy. TEM observation revealed little physical damage in CoCrPt dots though an ion milling process was employed for etching the magnetic layer. Degradation in the magnetic anisotropy energy was also found to be slight by the estimation with a micromagnetic simulation. A master plate with the AASA pattern has been developed. This removes the annealing process from the fabrication process and improves the throughput. Pattern transfer of the AASA master into the photopolymer layer was successful.