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Program Speakers  Preliminary Program<< Back |
Dr. Thomas R. AlbrechtHitachi Global Storage Technologies, Inc. FABRICATION OF LARGE ARRAYS OF ~10 NM FEATURES FOR PATTERNED MEDIA In the hard disk drive (HDD) industry, further increases in data capacity via optimization of grain properties of conventional granular magnetic recording media have become increasingly difficult. In recent years, growth in areal density has slowed to <10% per year, after many decades of growth at 25 - 100% per year. Bit patterned media (BPM) stand as an alternative to granular media, offering a path to thermally stable recording at higher density by replacing the segregated random grains of conventional media with lithographically defined single domain islands. Cost effective high volume manufacturing of BPM, however, requires successful implementation of innovative methods of pattern generation, replication, and transfer to magnetic films. One viable fabrication strategy for BPM entails (1) a combination of rotary-stage e-beam lithography, block copolymer (BCP) self-assembly, and self-aligned double patterning (SADP) to create large area master patterns of dense features in circular tracks; (2) high volume pattern replication via UV-cure nanoimprinting; and (3) pattern transfer to a magnetic recording layer via ion beam etching, ion implantation, or templated growth. At the required ~10 nm feature size, achieving tight tolerances for CD, placement, and edge roughness requires utmost attention to mitigation of pattern degradation at every process step. BPM fabrication differs substantially from processes employed for semiconductor manufacturing. BPM feature size is significantly smaller than dimensions given by the semiconductor industry lithography roadmap. Patterns must be seamless (stitch-free) in circular patterns extending over a full 65 or 95 mm diameter disk. Furthermore, HDD media is produced in much higher volume and requires an exceedingly low cost target. Fortunately, BPM has only a single lithography step with minimal overlay requirements, and fairly high levels of defects can be tolerated. BCP self-assembly and SADP have proven to be indispensible for generating suitable BPM master patterns. The use of BCP self-assembly for BPM represents one of the most advanced applications of this newly developed lithographic process in the ~10 nm feature size regime. New pattern transfer approaches, such as block-selective infiltration synthesis, play a major role in successful use of BCP patterns for real device fabrication with tight tolerance control. The BPM fabrication approach described above has been successfully demonstrated at 1.2 teradot/in2. Recording studies on such media provide insight into the extendibility of BPM technology. Fabrication innovations driven by the HDD industry for BPM may also prove useful in other industries, opening routes to practical manufacturing solutions for a variety of new applications. |