Kazuhiko Kobayashi

Preparation of Diamond Mold Using Electron Beam Lithography for Application to Nanoimprint Lithography

Diamond molds were fabricated by two types of fabrication processes, both of which use a conductive intermediate layer between the diamond surface and polymethylmethacrylate (PMMA) resist to prevent surface charge-up. Using a PtPd intermediate layer, electron beam lithography and ion beam etching, a denting line pattern of 600 nm width and 70 nm depth was fabricated. Using a carbon intermediate layer, electron beam lithography, PtPd lift-off and oxygen ion beam etching, a convex line pattern of 600 nm width and 110 nm height was fabricated. These diamond molds were pressed into PMMA on a silicon substrate that was heated to a temperature of 150°C and kept at a pressure of 23.5 MPa until the temperature dropped below 90°C, and then the diamond mold was released from the PMMA. The convex line pattern of 600 nm width and 150 nm height was imprinted using a denting diamond mold. The denting pattern of 1100 nm width and 180 nm height was imprinted using a convex diamond mold. PMMA patterns were transferred well over the imprinted area by the diamond molds.

Continuous-Stage-Movement Blankingless Electron-Beam Lithography for Patterned Media Template Fabrication

A slider and spindle (r–θ) stage electron beam (e-beam) mastering system with continuous-stage-movement blankingless beam shift lithography (BLSL) and flyback e-beam lithography (CSFL) brings together the features of high resolution, high accuracy, and high throughput to meet the various requirements for fabricating master templates for discrete track media and bit patterned media (BPM) for the next generation of hard disk drives. With the CSFL capability, we achieve multiple-overlay bit writing with one, two, four, and eight overlays for a BPM bit array to markedly improve track-to-track phase alignment accuracy from 5.6 nm sigma in a single write to 1.04 nm sigma in an eight overlay write. CSFL, in conjunction with the high-frequency response of the e-beam deflector, achieves 25 MHz high-throughput BPM bit array write with track pitches and bit pitches of 120 nm in the entire write range from 20 to 140 mm in diameter. This write takes only 11.6 h under the conditions of a line velocity of 3,000 mm/s, a beam current of 150 nA, a maximum rotation speed of 2,865 rpm, and a constant line velocity (CLV) write mode.