Low molecular weight P2VP-b-PS-b-P2VP triblock copolymer (poly(2-vinlypyridine)-block-polystyrene-block-poly(2-vinylpyridine)] is doped with copper chloride and microphase separated into lamellar line patterns with ultrahigh area density. Salt-doped P2VP-b-PS-b-P2VP triblock copolymer is self-assembled on the top of the nanoimprinted photoresist template, and metallic nanowires with long-range ordering are prepared with platinum-salt infiltration and plasma etching.

Directed self-assembly (DSA) of block copolymer (BCP) holds great promise for many applications in nanolithography, including the next generation magnetic recording. In this work, directed self-assembly of block copolymer technique has been combined with rotary stage electron beam mastering to fabricate a circular full track nanoimprint template for bit patterned media (BPM) fabrication. In order to meet specific requirements in pattern structure and format between the data and the servo zone in a servo-integrated template, three types of lithographically defined prepatterns, (1) two-dimensional chemical pre-pattern, (2) twodimensional low-topographic pre-pattern, and (3) one-dimensional high-topographic pre-pattern, have been explored for DSA process with two types of commercially available BCP thin film materials: cylinder-forming poly(styrene-b-methyl methacrylate) (PS-b-PMMA) and sphere-forming poly(styrene-b-dimethylsiloxane) (PS-b-PDMS). All guided BCP patterns exhibit highly ordered hexagonal close-packed (hcp) structures with high pattern quality. Using these BCP patterns, two polarities of dots-array templates (hole-tone and pillar-tone) with integrated servo patterns have been fabricated on a fused silica substrate at a density greater than 1.0 Td/in 2. Furthermore, the fabricated master template has been used for UV-cure nanoimprint lithography process development on 2.5 inch disk size media. Good pattern uniformity in imprint resist has been achieved over an entire 2.4 mm wide band area. The imprint resist patterns have been further transferred into underlying CoCrPt media by ion beam etching. Evidently, for the first time, the patterned CoCrPt alloy dots (hcp pattern) have successfully been demonstrated at a high density of 1.5 Td/in 2 (pitch = 22.3 nm) for a guided media (≅ 7 kOe) and 3.2 Td/in 2 (pitch = 15.2 nm) for an unguided media (≅ 5 kOe).

A microcolumn array has been designed, fabricated, and tested. The 2ϫ2 array has a 2 cm pitch and operates at 1 keV. Key components include vertical interconnects, silicon low-distortion octupole deflectors, miniature long-range flexure-based tip positioners, and low-power thermal field emitters. Initial results show no observable crosstalk between columns during simultaneous operation at a 50 MHz beam blanking rate. Preliminary lithography results are presented.

A hybrid directed self-assembly approach is developed to fabricate unprecedented servo-integrated bit-patterned media templates, by combining sphere-forming block copolymers with 5 teradot/in.(2) resolution capability, nanoimprint and optical lithography with overlay control. Nanoimprint generates prepatterns with different dimensions in the data field and servo field, respectively, and optical lithography controls the selective self-assembly process in either field. Two distinct directed self-assembly techniques, low-topography graphoepitaxy and high-topography graphoepitaxy, are elegantly integrated to create bit-patterned templates with flexible embedded servo information. Spinstand magnetic test at 1 teradot/in.(2) shows a low bit error rate of 10(-2.43), indicating fully functioning bit-patterned media and great potential of this approach for fabricating future ultra-high-density magnetic storage media.

Abstract. Directed self-assembly (DSA) of block copolymers (BCPs) proves to be a viable solution for the ultrahigh density bit-patterned media (BPM) application. However, servo design integration is still extremely challenging since the servo layouts require more complex patterns than the simple arrays naturally achieved by the DSA process. We present an integration scheme to create BPM servo patterns by utilizing the BCP dot-array patterns. This proposed method is based on an imprint guided two-step DSA process, combined with conventional optical lithography to define two separate zones. Both the data zone and servo zone consist of selfassembled hexagonal dot arrays: a regular pattern in the data zone and an arbitrary pattern in the servo zone. This method was successfully used to fabricate a servo-integrated BPM template with an areal density of 1.5 Teradot∕inch 2 (Td∕in: 2 ) (L o ¼ 22.3 nm). Using the fabricated quartz template, CoCrPt BPM media has been successfully patterned by nanoimprint lithography and subsequent ion-beam etching process on a 2.5 in. disk. Further, using patterned-in servo wedges on 1.5 Td∕in:2 patterned CoCrPt media, we are able to close the servo control loop for track-following on a spin-stand test. The standard deviation of repeatable run-out over the full revolution is calculated to be about 4% of the 38.6 nm track pitch. This method is currently being used to fabricate a template at a much higher density of 3.2 Td∕in: 2 (L o ¼ 15.2 nm). © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.