Fabrication and Recording of Bit Patterned Media Prepared by Rotary Stage Electron Beam Lithography

Abstract

Bit patterned media (BPM) is a promising technology for hard disk drive recording at ultra-high areal densities of 1 Tbit/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and beyond. However, for BPM to be commercially viable, nanoscale bit patterns must be fabricated at low cost on a large scale and with low defect densities. The most likely route to realizing such criteria is through the use of high throughput nanoimprint lithography followed by direct etching of the recording media, where the bit pattern template is generated by highly accurate electron beam mastering tools. In this work, we experimentally demonstrate the merits of rotary stage electron beam mastering and the subsequent effects of direct pattern transfer on BPM and servo arrays patterned into 2.5" commercially available CoCrPt perpendicular recording media (PRM) at a density of 366 Gbit/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The 42 nm pitch staggered bit patterns and corresponding servo arrays were lithographically generated by a Pioneer Corporation EBR-401 rotary stage electron beam mastering system and subsequently transferred into the media using a series of reactive ion etching and ion milling processes with C/SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> mask structures and a novel Al protection layer. The fabricated media was recorded and read back with a commercial recording head to verify pattern fidelity.