Super-resolution Imaging by Evanescent Wave Coupling to Surface States on Effective Gain Media

TL;DR

This paper introduces a method using evanescent wave coupling to surface states on effective gain media to achieve super-resolution imaging at high numerical apertures in semiconductor lithography.

Contribution

It demonstrates how evanescent wave coupling to surface states on effective gain media can overcome surface confinement limits at high NAs, enabling higher resolution lithography.

Findings

Achieved high aspect ratio structures at NAs of 1.85 and beyond.

Countered image decay using sapphire on SiO2 layer.

Enabled 26-nm resolution at 193 nm wavelength.

Abstract

Higher resolution demands for semiconductor lithography may be fulfilled by higher numerical aperture (NA) systems. However, NAs more than the photoresist refractive index (~1.7) cause surface confinement of the image. In this letter we describe how evanescent wave coupling to effective gain medium surface states beneath the imaging layer can counter this problem. At {\lambda}=193 nm a layer of sapphire on SiO2 counters image decay by an effective-gain-medium resonance phenomena allowing evanescent interferometric lithography to create high aspect ratio structures at NAs of 1.85 (26-nm) and beyond.