Superconducting Through-Substrate Vias on Sapphire Substrates for Quantum Circuits

Sapphire substrates have recently been recognized for their potential to improve the coherence time of superconducting qubits. However, due to challenges in via fabrication, silicon substrates have been predominantly used for qubits. In this study, we fabricated vias on sapphire substrates using las...

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Bibliographic Details
Published in:IEEE transactions on quantum engineering 2024, Vol.5, p.1-4
Main Authors: Mukasa, Kiyotaka, Nuruki, Yusuke, Kubo, Hayato, Narahara, Yoshihide, Umehara, Motohiro, Fujie, Kazuyuki
Format: Article
Language:English
Subjects:
Chemical vapor deposition
Coherence
Qubit
Qubits (quantum computing)
Sapphire
Sapphire substrates
Silicon substrates
Substrates
Superconducting films
Superconducting microwave devices
superconducting qubits
Superconducting transition temperature
Superconductivity
Thickness
through-substrate vias
Tin
Titanium nitride
titanium nitride (TiN)
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Summary:Sapphire substrates have recently been recognized for their potential to improve the coherence time of superconducting qubits. However, due to challenges in via fabrication, silicon substrates have been predominantly used for qubits. In this study, we fabricated vias on sapphire substrates using lasers and deposited TiN films by chemical vapor deposition. Cross-sectional views of the via confirmed uniform thickness of the TiN film along the via wall. In addition, the TiN film exhibited a superconducting transition at 4.5 K, demonstrating the successful deposition of a high-quality homogeneous superconducting film. This represents the first example of realizing superconducting through-substrate vias on sapphire substrates, a crucial first step toward achieving the 3-D integration of qubits while maintaining coherence time.
ISSN:2689-1808
2689-1808
DOI:10.1109/TQE.2024.3416963