Dresden 2020 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 16: Poster Session Superconductivity, Cryogenic Particle Detectors, Cryotechnique
TT 16.23: Poster
Monday, March 16, 2020, 15:00–19:00, P2/EG
Development of a fabrication process for nanoSQUIDs with three independent Nb layers — •Silke Wolter1, Oliver Kieler1, Thomas Weimann1, Josepha Altmann2, Sylke Bechstein2, Jörn Beyer2, Julian Linek3, Reinhold Kleiner3, and Dieter Koelle3 — 1Fachbereich Quantenelektronik, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig — 2Fachbereich Kryosensorik, Physikalisch-Technische Bundesanstalt (PTB), Berlin — 3Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen
Nanometer-sized superconducting quantum interference devices, nanoSQUIDs (nSQs), offer high spatial resolution und high spin sensitivity approaching the order of 1 µB/Hz1/2 (µB is the Bohr magneton), making them suitable for the detection of the magnetic states of magnetic nanoparticles. Our fabrication technology for nSQs with overdamped SNS (S: superconductor, N: normal conductor) trilayer Nb-HfTi-Nb Josephson junctions is based on the combination of electron beam lithography with chemical-mechanical polishing and magnetron sputtering on thermally oxidized Si wafers to produce dc nSQs with 100-nm-dimensions for Nb lines and junctions (down to 80 nm× 80 nm). We extended the process from originally two to three independent Nb layers. This extension offers the possibility to increase the density of structures on the wafer and to realize superconducting vias to all Nb layers without the HfTi barrier. We present results on the yield of this process and measurements of nSQs characteristics.
This work was supported by the DFG (KI 698/3-2).