Superconducting tunnel junction fabrication on three-dimensional topography via direct laser writing

TL;DR

This paper introduces a novel 3D fabrication method for superconducting tunnel junctions using direct laser writing, enabling device creation on complex topographies beyond flat surfaces.

Contribution

It demonstrates the first successful fabrication of high-quality NIS tunnel junctions on 3D structures using maskless two-photon lithography.

Findings

Successful fabrication of NIS junctions on 20 μm tall 3D topography

Potential for sub-micron device fabrication on complex surfaces

Technique compatible with advanced resist coating methods

Abstract

Superconducting junctions are widely used in multitude of applications ranging from quantum information science and sensing to solid-state cooling. Traditionally, such devices must be fabricated on flat substrates using standard lithographic techniques. In this study, we demonstrate a highly versatile method that allows for superconducting junctions to be fabricated on a more complex topography. It is based on maskless direct laser writing (DLW) two-photon lithography, which allows writing in 3D space. We show that high-quality normal metal-insulator-superconductor (NIS) tunnel junctions can be fabricated on top of a 20 $\mu$m tall three-dimensional topography. Combined with more advanced resist coating methods, this technique could allow sub-micron device fabrication on almost any type of topography in the future.