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Open Access Nano Express

Versatile pattern generation of periodic, high aspect ratio Si nanostructure arrays with sub-50-nm resolution on a wafer scale

Jian-Wei Ho123*, Qixun Wee234, Jarrett Dumond3, Andrew Tay5 and Soo-Jin Chua2346*

Author Affiliations

1 NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore 117456, Singapore

2 Centre for Optoelectronics, Department of Electrical and Computer Engineering, National University of Singapore, Block E3 02-07, Engineering Drive 3, Singapore 119260, Singapore

3 Institute of Materials Research and Engineering, Agency for Science Technology and Research (A*STAR), 3 Research Link, Singapore 117602, Singapore

4 Singapore-MIT Alliance, National University of Singapore, Block E4 04-10, 4 Engineering Drive 3, Singapore 117576, Singapore

5 Department of Mechanical Engineering, National University of Singapore, Block EA 07-08, 9 Engineering Drive 1, Singapore 117576, Singapore

6 Singapore-MIT Alliance for Research and Technology Center, 1 CREATE Way, #10-01 CREATE Tower, Singapore 138602, Singapore

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Nanoscale Research Letters 2013, 8:506  doi:10.1186/1556-276X-8-506

Published: 1 December 2013

Abstract

We report on a method of fabricating variable patterns of periodic, high aspect ratio silicon nanostructures with sub-50-nm resolution on a wafer scale. The approach marries step-and-repeat nanoimprint lithography (NIL) and metal-catalyzed electroless etching (MCEE), enabling near perfectly ordered Si nanostructure arrays of user-defined patterns to be controllably and rapidly generated on a wafer scale. Periodic features possessing circular, hexagonal, and rectangular cross-sections with lateral dimensions down to sub-50 nm, in hexagonal or square array configurations and high array packing densities up to 5.13 × 107 structures/mm2 not achievable by conventional UV photolithography are fabricated using this top-down approach. By suitably tuning the duration of catalytic etching, variable aspect ratio Si nanostructures can be formed. As the etched Si pattern depends largely on the NIL mould which is patterned by electron beam lithography (EBL), the technique can be used to form patterns not possible with self-assembly methods, nanosphere, and interference lithography for replication on a wafer scale. Good chemical resistance of the nanoimprinted mask and adhesion to the Si substrate facilitate good pattern transfer and preserve the smooth top surface morphology of the Si nanostructures as shown in TEM. This approach is suitable for generating Si nanostructures of controlled dimensions and patterns, with high aspect ratio on a wafer level suitable for semiconductor device production.