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Research Letters in Nanotechnology
Volume 2008, Article ID 765398, 4 pages
Research Letter

Achieving High Aspect Ratio of Track Length to Width in Molds for Discrete Track Recording Media

1Data Storage Institute, A STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, Singapore 117608
2Department of Electrical and Computer Engineering, National University of Singapore 4 Engineering Drive 3, Singapore 117576

Received 29 November 2007; Accepted 5 February 2008

Academic Editor: Sakhrat Khizroev

Copyright © 2008 K. O. Aung et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Discrete track media (DTM) fabricated by nanoimprint lithography (NIL) is considered as a potential technology for future hard disk drives (HDD). In the fabrication of a master mold for NIL, patterning the resist tracks with a narrow distribution in the width is the first critical step. This paper reports the challenges involved in the fabrication of high aspect ratio discrete tracks on Polymethylmethacrylate (PMMA) resist by means of electron beam lithography. It was observed that fabrication parameters applied for successful patterning of discrete tracks in nanoscale length were not directly suitable for the patterning of discrete tracks in micron scale. Hence different approaches such as thick layer resist coating, introducing of post exposure baking process, and varying of exposure parameters were used in order to achieve uniform sharp discrete tracks in micron scale length on the resist. The optimal parameters were used to pattern 20  ๐œ‡ m long tracks with 70 nm track pitch on the resist.