Nanoscale wireframe SQUID on a cantilever by corner lithography

TL;DR

This paper introduces a novel fabrication method for nanoscale superconducting quantum interference devices (SQUIDs) on cantilever tips, enabling high-precision magnetic sensing with tunable and scalable features.

Contribution

It presents a new fabrication process combining corner lithography and shadow deposition to create wafer-scale, tunable nanoscale SQUIDs on cantilever probes.

Findings

SQUIDs with effective diameters down to 100 nm

Operation in magnetic fields up to 1 Tesla

Local flux modulation capability

Abstract

We present the fabrication of nanoscale superconducting quantum interference devices (SQUIDs) at the apex of wireframe tips on self-aligned superconducting cantilever probes. The probes are made on silicon wafers using molding techniques in combination with corner lithography, which results in a nanowire frame tip with a tuneable apex structure. A shadow effect deposition using magnetron sputtering of Nb creates self-aligned superconducting wireframes on cantilevers with accompanying device circuitry. Superconducting weak links are realized at the apex of the wireframes with the use of focused ion beam nanopatterning. The realized SQUIDs have effective diameters ranging from several micrometers down to 100 nm and can be operated in magnetic fields up to 1 T. Furthermore, the nanowires in the wireframe can be used to flux modulate the SQUID locally. This fabrication process enables the production of wafer-scale templates for probes based on on-tip superconducting devices.