Ultrahigh-density storage media prepared by artificially assisted self-assembling methods

Two types of recording media possessing nanodot structures were investigated. The media were prepared by an artificially assisted self-assembling (AASA) method, which includes simple nanopatterning using a nanoimprint and fine nanopatterning using self-assembling organic molecules. One type of recording media is circumferential magnetic patterned media prepared on a 2.5-in.-diam glass plate. A Ni master disk possessing spiral patterns with 60-250 nm width lands and a 400 nm width groove was pressed to a resist film on a CoCrPt film to transfer the spiral patterns. A diblock copolymer solution was cast into the obtained grooves, and then annealed to prepare self-assembling dot structures aligned along the grooves. According to the dot patterns, the lower magnetic films were patterned by ion milling to yield patterned media with 40 nm diameter. We have also prepared FePt dot media with high magnetic anisotropy for near-field and magnetic-field hybrid recording aiming at more than 1 Tbin.2 density. A Ni stamp disk with aligned dot structures was also prepared by the AASA method to produce patterned media at the lowest cost. The other type of media was organic patterned media for X-Y type near-field optical storage. Bulky dye molecules were evaporated in vacuum to produce self-assembling amorphous nanodots. The dots were arranged by the AASA method, i.e., according to the polymethylmethacrylate film hole arrays or chemically patterned surface.