Open AccessAccurate near-field lithography modeling and quantitative mapping of the near-field distribution of a plasmonic nanoaperture in a metal
Author(s) -
Yongwoo Kim,
Howon Jung,
Seok Kim,
Jinhee Jang,
Jae Yong Lee,
Jae Won Hahn
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.019296
Subject(s) - optics , photoresist , optical proximity correction , nanolithography , critical dimension , materials science , near and far field , field (mathematics) , intensity (physics) , lithography , physics , nanotechnology , fabrication , layer (electronics) , medicine , alternative medicine , mathematics , pathology , pure mathematics
In nanolithography using optical near-field sources to push the critical dimension below the diffraction limit, optimization of process parameters is of utmost importance. Herein we present a simple analytic model to predict photoresist profiles with a localized evanescent exposure that decays exponentially in a photoresist of finite contrast. We introduce the concept of nominal developing thickness (NDT) to determine the proper developing process that yields the best topography of the exposure profile fitting to the isointensity contour. Based on this model, we experimentally investigated the NDT and obtained exposure profiles produced by the near-field distribution of a bowtie-shaped nanoaperture. The profiles were properly fit to the calculated results obtained by the finite differential time domain method. Using the threshold exposure dose of a photoresist, we can determine the absolute intensity of the intensity distribution of the near field and analyze the difference in decay rates of the near field distributions obtained via experiment and calculation. For maximum depth of 41 nm, we estimate the uncertainties in the measurements of profile and intensity to be less than 6% and about 1%, respectively. We expect this method will be useful in detecting the absolute value of the near-field distribution produced by nano-scale devices.