Toshinori Ono

Fabrication of Planarized Discrete Track Media Using Gas Cluster Ion Beams

Fabrication of planarized discrete track media (DTM) by using gas cluster ion beams (GCIB) was demonstrated. Line-and-space patterns were fabricated using nanoimprint lithography and ion beam etching. These patterns were refilled by TiCr films, and the TiCr surface was planarized using Ar and N2-GCIBs. The GCIB process yielded excellent planarization of these patterns owing to the preferential modification of surface bumps and enhancement of the surface motion of atoms by GCIB irradiation. The flyability test of a slider flying at a 10-nm height on the DTM planarized with GCIBs indicated an almost 10% reduction in the acoustic emission (AE) output. Further, magnetic force microscope (MFM) and Kerr rotation measurements revealed that GCIB planarization did not produce any significant change in the magnetic characteristics of DTM. It was demonstrated that GCIB planarization is effective for fabricating DTM or similar structures such as bit-patterned media (BPM).

Fabrication of Discrete Track Media by Cr Ion Implantation

Discrete track media were successfully fabricated by Cr ion implantation. The saturation magnetization of the CoCrPt-SiO2 perpendicular recording layer was decreased down to 6% by implanting Cr ions with a dosage of 1 × 1017 ions/cm and an ion energy of 20 keV. A resist mask with a discrete track pattern was prepared by e-beam lithography and the pattern was transferred to the recording layer by Cr ion implantation. A clear magnetic contrast of the tracks was observed and the average surface roughness was maintained less than 1 nm. A clear servo signal was obtained by spin-stand measurement using a flying head. Feasibility of discrete track media fabrication by Cr ion implantation was confirmed.