Tantalum thin films sputtered on silicon and on different seed layers: material characterization and coplanar waveguide resonator performance

Fuente: arXiv
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Auteurs principaux: Singer, Moritz, Schoof, Benedikt, Gupta, Harsh, Zahn, Daniela, Weber, Johannes, Tornow, Marc
Format: Preprint
Publié: 2024
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author Singer, Moritz
Schoof, Benedikt
Gupta, Harsh
Zahn, Daniela
Weber, Johannes
Tornow, Marc
author_facet Singer, Moritz
Schoof, Benedikt
Gupta, Harsh
Zahn, Daniela
Weber, Johannes
Tornow, Marc
contents Superconducting qubits are a promising platform for large-scale quantum computing. Besides the Josephson junction, most parts of a superconducting qubit are made of planar, patterned superconducting thin films. In the past, most qubit architectures have relied on niobium (Nb) as the material of choice for the superconducting layer. However, there is also a variety of alternative materials with potentially less losses, which may thereby result in increased qubit performance. One such material is tantalum (Ta), for which high-performance qubit components have already been demonstrated. In this study, we report the sputter-deposition of Ta thin films directly on heated and unheated silicon (Si) substrates as well as onto different, nanometer-thin seed layers from tantalum nitride (TaN), titanium nitride (TiN) or aluminum nitride (AlN) that were deposited first. The thin films are characterized in terms of surface morphology, crystal structure, phase composition, critical temperature, residual resistance ratio (RRR) and RF-performance. We obtain thin films indicative of pure alpha-Ta for high temperature (600°C) sputtering directly on silicon and for Ta deposited on TaN or TiN seed layers. Coplanar waveguide (CPW) resonator measurements show that the Ta deposited directly on the heated silicon substrate performs best with internal quality factors $Q_i$ reaching 1 x $10^6$ in the single-photon regime, measured at $T=100 {\space \rm mK}$.
format Preprint
id arxiv_https___arxiv_org_abs_2409_06041
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tantalum thin films sputtered on silicon and on different seed layers: material characterization and coplanar waveguide resonator performance
Singer, Moritz
Schoof, Benedikt
Gupta, Harsh
Zahn, Daniela
Weber, Johannes
Tornow, Marc
Materials Science
Quantum Physics
Superconducting qubits are a promising platform for large-scale quantum computing. Besides the Josephson junction, most parts of a superconducting qubit are made of planar, patterned superconducting thin films. In the past, most qubit architectures have relied on niobium (Nb) as the material of choice for the superconducting layer. However, there is also a variety of alternative materials with potentially less losses, which may thereby result in increased qubit performance. One such material is tantalum (Ta), for which high-performance qubit components have already been demonstrated. In this study, we report the sputter-deposition of Ta thin films directly on heated and unheated silicon (Si) substrates as well as onto different, nanometer-thin seed layers from tantalum nitride (TaN), titanium nitride (TiN) or aluminum nitride (AlN) that were deposited first. The thin films are characterized in terms of surface morphology, crystal structure, phase composition, critical temperature, residual resistance ratio (RRR) and RF-performance. We obtain thin films indicative of pure alpha-Ta for high temperature (600°C) sputtering directly on silicon and for Ta deposited on TaN or TiN seed layers. Coplanar waveguide (CPW) resonator measurements show that the Ta deposited directly on the heated silicon substrate performs best with internal quality factors $Q_i$ reaching 1 x $10^6$ in the single-photon regime, measured at $T=100 {\space \rm mK}$.
title Tantalum thin films sputtered on silicon and on different seed layers: material characterization and coplanar waveguide resonator performance
topic Materials Science
Quantum Physics
url https://arxiv.org/abs/2409.06041