Nanoscale 2.5-dimensional surface patterning with plasmonic lithography

Abstract

We report an extension of plasmonic lithography to nanoscale 2.5-dimensional (2.5D) surface patterning. To obtain the impulse response of a plasmonic lithography system, we described the field distribution of a point dipole source generated by a metallic ridge aperture with a theoretical model using the concepts of quasi-spherical waves and surface plasmon–polaritons. We performed deconvolution to construct an exposure map of a target shape for patterning. For practical applications, we fabricated several nanoscale and microscale structures, such as a cone, microlens array, nanoneedle, and a multiscale structure using the plasmonic lithography system. We verified the possibility of applying plasmonic lithography to multiscale structuring from a few tens of nanometres to a few micrometres in the lateral dimension. We obtained a root-mean-square error of 4.7 nm between the target shape and the patterned shape, and a surface roughness of 11.5 nm.

Plasmonic Lithography: Recent Progress

“…Plasmonic aperture probe writing was first introduced by Hahn's group . The bowtie aperture, fabricated using focused ion beam milling in 120 nm Al film with 20 nm center ridge gap, could be used directly for writing 50 nm wide 5–10 nm deep lines from 405 nm lasers in contact mode ( Figure ).…”

Quantitative analysis and modeling of line edge roughness in near-field lithography: toward high pattern quality in nanofabrication

“…Accordingly, a critical step to fully capture the effect of near-field distribution on the pattern quality is to quantify the PR PSF. Extraction of the PR PSF from spot-mapping patterns using a calibration process has been demonstrated, and it plays an important role in the pattern profile prediction [5][6]. However, LER is related to the edge roughness of the line patterns, which means that LER generation is mainly affected by the outermost edge field distribution at the exit of the plasmonic BNA.…”

“…Near-field lithography (NFL) is a sub-diffraction-limited nanopatterning technology by exploiting surface plasmon polaritons (SPPs) and the diffracted field such as quasi-spherical waves (QSWs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. These waves are excited by an incident light and confined in the horizontal plane and the perpendicular direction through strong near-field coupling via evanescent photons.…”

“…As an alternative low-cost nanofabrication, the pattern resolution of NFL has been successfully demonstrated with a below-20-nm half-pitch by employing a plasmonic bowtie nanoaperture (BNA) [3,14]. The advances in nanoscale feature-size controllability and scalability allow NFL to be used for 1-to 2.5-dimensional surface nanofabrication [2,3,6,15]. Furthermore, optical proximity correction methods have also been proposed to achieve high pattern fidelity control by adjusting the proximity effects caused by evanescent waves [16][17][18].…”

“…Furthermore, optical proximity correction methods have also been proposed to achieve high pattern fidelity control by adjusting the proximity effects caused by evanescent waves [16][17][18]. However, the previously reported experimental results suffer from a critical issue in terms of line edge roughness (LER) even over a small patterning area, which can limit the applications of NFL [2,3,6,16,19,20].…”