Using a simple theoretical model, we calculated three-dimensional profiles of photoresists that were exposed by arbitrarily-shaped localized fields of high-transmission metal nano-apertures. We applied the finite-difference time-domain (FDTD) method to obtain the localized field distributions. These distributions are generated by excitation of localized surface plasmon polaritons underneath a circular, C-shaped or bowtie-shaped aperture. We predicted the two-dimensional exposure profiles of the photoresist as a function of the photoresist contrast when the results of the FDTD simulations were applied to the theoretical model. The three-dimensional exposure profiles of the photoresist were also visualized as a function of the exposure dose and the gap distance between the aperture and the photoresist. The three-dimensional exposure profiles provided useful information in determining the process parameters for nano-patterning by plasmonic lithography using the high-transmission nano-aperture.
We design a C-shaped aperture which overcomes the diffraction limit of light to produce a high-brightness nano-size
light spot. For optical nano lithography, we construct a nano patterning system using an optical probe which adopts a
solid immersion lens (SIL), the 120 nm thickness aluminum film on the bottom surface of the SIL and the C-shaped
aperture engraved in the metal film. Light source is a diode laser of 405nm wavelength to expose h-line photoresist(PR).
A linear stage holding the optical probe makes the nano aperture contact with the PR coated on silicon wafer. Using this
patterning system, we obtain sub 100nm array patterns and measure the system performance in various exposure
conditions to verify the feasibility of plasmonic lithography.
Due to the maturity of current laser technology, the limitation of empirical wavelengths of lasers useful for optical
microlithography makes spectrally investigated optimization very important for the design of C-shaped nano apertures;
in order to achieve high optical transmission as well as tight focusing, the resonant transmission of nano apertures
depends on the incident light's wavelength. The optically propagating transmission through the nano aperture,
determined by the effects of the propagating field and evanescent field, is also important in order to achieve deep
patterning. High power throughput and decaying behaviors of propagating light through nano apertures depend on their
resonance condition which is affected by geometric parameters and material properties as well as the wavelength of
incident light. In this report, we analyze the spectral properties of resonant transmission of light through a C-shaped
nano aperture in a metal film using a finite-difference time-domain (FDTD) simulation. These simulations may be
helpful for the design of C-shaped nano apertures for high power throughput with tight focusing. Furthermore, we show
that power dissipation of propagating light through the C-shaped nano aperture depends on metals.
In this paper, based on numerical study using the finite difference time domain method, we designed metal slits for
higher harmonic fringe patterns generated with surface plasmon interference lithography. The slits were designed to
generate higher fringe patterns having high intensity output, high contrast and good uniformity in sub-100nm scale.
After fabricating several types of slits on aluminum film mask according to the calculated designs with a focused ion
beam facility, lithography experiments using the aluminum slits were performed to record the near-filed fringe patterns
using i-line Hg lamp and SU-8 negative photoresist.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.