Technology of fabrication superconducting free-standing structures (FSS)

• Published in: Superconductor science & technology 2024-12, Vol.37 (12), p.125004
• Main Authors: Tarkhov, M A, Mumlyakov, A M, Shibalov, M V, Porokhov, N V, Vovk, N A, Nekludova, P A, Trofimov, I V, Filippov, I A
• Format: Article
• Language: English
• Subjects: bolometer; low pressure chemical etching; niobium nitride; superconducting free-standing structure; superconducting nanowire single photon detector
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/1361-6668/ad8af6

In this study, a method for fabrication of superconducting microstructures that are partially or completely isolated from the substrate has been proposed. Two configurations of suspended micro-bridges have been suggested, i.e. the first structure that features a T-shaped etching of the substrate and the second structure which is completely separated from the substrate through periodically positioned supports. The creation of suspended structures is based on the principle of gas-phase etching of amorphous silicon oxide in a mixture of hydrogen fluoride and ethanol gases. In the course of the experiments, it has been discovered that suspending micro-structures in the configuration of a micro-bridge results in a slight reduction in superconducting characteristics, ranging from 10%–15% of the initial parameters. It has also been demonstrated that the thermal coupling between the film and the substrate significantly affects the dissipation of thermal energy. The power dissipated into the substrate at room temperature can vary by up to 250 times based on the value of the micro-bridge undercutting.