Pushing the resolution of photolithography down to 15nm by surface plasmon interference

Abstract

A deep ultraviolet plasmonic structure is designed and a surface plasmon interference lithography method using the structure is proposed to generate large-area periodic nanopatterns. By exciting the anti-symmetric coupled surface plasmon polaritons in the structure, ultrahigh resolution periodic patterns can be formed in a photoresist. The resolution of the generated patterns can be tuned by changing the refractive index and thickness of the photoresist. We demonstrate numerically that one-dimensional and two-dimensional patterns with a half-pitch resolution of 14.6 nm can be generated in a 25 nm-thick photoresist by using the structure under 193 nm illumination. Furthermore, the half-pitch resolution of the generated patterns can be down to 13 nm if high refractive index photoresists are used. Our findings open up an avenue to push the half-pitch resolution of photolithography towards 10 nm.

Nanostructure and Microstructure Fabrication: From Desired Properties to Suitable Processes

“…A challenge with plasmonic lithography is that SPPs decay faster than photons (in the order of 5–20 nm), only allowing for proximity lengths that are much shorter than those achieved with proximity photolithography . Feature sizes down to 22 nm have been demonstrated, by projecting a ring‐shaped interference pattern of plasmonic oscillations on a resist layer .…”

Plasmonic Lithography: Recent Progress

“…Xu et al in 2009 mathematically simulated the surface plasmon modes of such cavity, showing feasibility of utilizing antisymmetric SPP modes to create deep subdiffractional and high aspect ratio structures . Dong et al pushed the simulated resolution to as small as 15 nm (half pitch) using 193 nm illumination . Early results presented by Gao et al showed an improvement of the low aspect ratio from smaller than 1:4 height:half‐pitch to about 1:1.4 .…”

“…A typical plasmon cavity setup. Reproduced with permission under a Creative Commons 3.0 licence . Copyright 2014, The Nature Publishing Group.…”

Optical elements based on silicon photonics

“…Due to the wavelengths typically used for optical transport and silicon's high index of refraction, the feature sizes required for processing these silicon WGs are on the order of 0.3-1 µm. The lithography requirements needed to process WGs with these sizes are easily available today [3].…”