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 μm 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.
@article{arxiv.2009.09749,
title = {Superconducting tunnel junction fabrication on three-dimensional topography via direct laser writing},
author = {Samuli Heiskanen and Ilari J. Maasilta},
journal= {arXiv preprint arXiv:2009.09749},
year = {2021}
}