IOP PUBLISHING
NANOTECHNOLOGY
Nanotechnology 24 (2013) 115306 (7pp)
doi:10.1088/0957-4484/24/11/115306
Post-lithography pattern modification and
its application to a tunable wire grid
polarizer
Michal Stach1, En-Chiang Chang1, Chung-Yuan Yang1 and
Cheng-Yao Lo1,2
1 Institute of NanoEngineering and MicroSystems, National Tsing Hua University, No. 101, Section 2,
Kuang Fu Road, Hsinchu, 30013, Taiwan, Republic of China
2 Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2,
Kuang Fu Road, Hsinchu, 30013, Taiwan, Republic of China
E-mail: chengyao@mx.nthu.edu.tw
Received 18 October 2012, in final form 28 January 2013
Published 28 February 2013
Online at stacks.iop.org/Nano/24/115306
Abstract
This study reports a simple and cost-effective post-lithography solution for reducing the
characteristic dimensions of structures on the nanometer scale using an external mechanical
force without any modification of the existing exposure system. In particular, this study
presents a tunable aluminum wire grid polarizer (WGP) made by a laser interference
lithography and i-line (365 nm) exposure setup on polyethylene naphthalate. The WGP
achieves a 58% maximum linewidth shrinkage of the metal nanowire on the polymer
substrate, and further improved the polarization extinction ratio by 83% with a defined
operation window and optimized strain. The simulations in this study prove the rise of the
extinction ratio with the modulation of the WGP pattern. Physical evidence explains the fall of
the extinction ratio for both the increase of the metal crack volume and the delaminated
randomly oriented fall-on fragments under extensive operation.
(Some figures may appear in colour only in the online journal)
1. Introduction
novel ideas such as electron-beam (e-beam) [13­15] and
focused ion-beam (FIB) [16, 17] writing as next-generation
Linewidth reduction, which is often necessary to meet
techniques. However, research on post-lithography process,
technological requirements, can be achieved using extreme
which could also further reduce pattern dimensions without
ultraviolet (EUV) lithography [1, 2] and immersion lithog-
performing an extra lithography process, is lacking.
raphy [3, 4]. Researchers and engineers generally achieve
Many research groups have focused on the elastic and
this by reducing the wavelength of the light source [5, 6],
plastic properties of inorganic nano-patterns fabricated on
enlarging the numerical aperture [7, 8] of the optical system
organic substrates with various materials and techniques.
or minimizing the process-related coefficient [9] during
The computational [18] and experimental [19, 20] results of
exposure. However, improving and overcoming the theoretical
these studies have potential applications in interconnections
limits [10] is challenging and costly, and encounters potential
and reliability improvements. However, most of these studies
issues in slowing down technological advancement and
viewed strain as a defect-forming or unexpected and unwanted
raising the investment barrier. The double patterning [11]
physical quantity. The critical strain points determined in
and photoresist (PR) treatment [12] methods have become
these studies only showed the drawbacks of material operation
two important proposals for pattern modification without
limits, and unintentionally concealed and neglected the
changing the exposure system. In addition to the parameters
potential advantages of the structure or the material in elastic
of conventional lithography, researchers have proposed
or plastic regions. Similarly, inorganic structures on organic
0957-4484/13/115306+07$33.00
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