Open Access Nano Express

SML resist processing for high-aspect-ratio and high-sensitivity electron beam lithography

Mohammad Ali Mohammad1*, Steven K Dew1 and Maria Stepanova12

Author affiliations

1 Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4, Canada

2 National Institute for Nanotechnology NRC, 11421 Saskatchewan Drive, Edmonton, Alberta, T6G 2M9, Canada

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Citation and License

Nanoscale Research Letters 2013, 8:139  doi:10.1186/1556-276X-8-139

Published: 27 March 2013

Abstract

A detailed process characterization of SML electron beam resist for high-aspect-ratio nanopatterning at high sensitivity is presented. SML contrast curves were generated for methyl isobutyl ketone (MIBK), MIBK/isopropyl alcohol (IPA) (1:3), IPA/water (7:3), n-amyl acetate, xylene, and xylene/methanol (3:1) developers. Using IPA/water developer, the sensitivity of SML was improved considerably and found to be comparable to benchmark polymethylmethacrylate (PMMA) resist without affecting the aspect ratio performance. Employing 30-keV exposures and ultrasonic IPA/water development, an aspect ratio of 9:1 in 50-nm half-pitch dense grating patterns was achieved representing a greater than two times improvement over PMMA. Through demonstration of 25-nm lift-off features, the pattern transfer performance of SML is also addressed.

Keywords:
SML resist; Electron beam lithography; High-aspect-ratio nanolithography; Nanolithography; Nanofabrication; Lift-off; Preventing pattern collapse; Resists (85.40.Hp); Electron beam lithography (85.40.Hp); Nanolithography (81.16.Nd)