Fabrication and analysis of metallic nanoslit structures: advancements in the nanomasking method

Abstract

, "Fabrication and analysis of metallic nanoslit structures: advancements in the nanomasking method," J. Micro/Nanolith. MEMS MOEMS 17(1), 013501 (2018), doi: 10.1117/1.JMM.17.1.013501. Abstract. This work advances the fabrication capabilities of a two-step lithography technique known as nanomasking for patterning metallic nanoslit (nanogap) structures with sub-10-nm resolution, below the limit of the lithography tools used during the process. Control over structure and slit geometry is a key component of the reported method, exhibiting the control of lithographic methods while adding the potential for mass-production scale patterning speed during the secondary step of the process. The unique process allows for fabrication of interesting geometric combinations such as dual-width gratings that are otherwise difficult to create with the nanoscale resolution required for applications, such as nanoscale optics (plasmonics) and electronics. The method is advanced by introducing a bimetallic fabrication design concept and by demonstrating blanket nanomasking. Here, the need for the secondary lithography step is eliminated improving the mass-production capabilities of the technique. Analysis of the gap width and edge roughness is reported, with the average slit width measured at 7.4 AE 2.2 nm. It was found that while no long-range correlation exists between the roughness of either gap edge, and there are ranges in the order of tens of nanometers over which the slit edge roughness is correlated or anticorrelated across the gap. This work helps quantify the nanomasking process, which aids in future fabrications and leads toward the development of more accurate computational models for the optical and electrical properties of fabricated devices. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 UnportedLicense. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

The Role of Rayleigh-Wood Anomalies and Surface Plasmons in Optical Enhancement for Nano-Gratings

“…The operating wavelength, λ 0 , was fixed at 875 nm, near the bandgap of GaAs, so that we could optimize GaAs photodetectors. The top edges of the nanostructures were rounded with a 3-nm radius to more closely match the fabricated structures, as demonstrated by standard lithographic methods [ 25 , 26 ]. Optical properties of materials (frequency-dependent) were taken from experimental results [ 27 , 28 ].…”

Plasmonic Au Array SERS Substrate with Optimized Thin Film Oxide Substrate Layer

“…Devices are then proposed for improved plasmonic surface enhancement both at optimized geometries and at resonant modes with larger structures/gaps. With larger gap and wire geometries providing significant enhancement, reliance on advanced two-step nanogap or nanoslit lithographic techniques can be eliminated [ 18 , 33 , 34 , 35 ]. While there are many nice techniques for obtaining quality SERS substrates [ 36 , 37 ], this work highlights that there are some interesting optical features in patterned nanograting structures that have not been fully explored.…”