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Layered Al2O3-SiO2 and Al2O3-Ta2O5 thin-film composites for high dielectric strength, deposited by pulsed direct current and radio frequency magnetron sputtering

Hanby, Benjamin V.T.; Stuart, Bryan W.; Gimeno-Fabra, Miquel; Moffat, Jonathan; Gerada, Chris; Grant, David M.

Layered Al2O3-SiO2 and Al2O3-Ta2O5 thin-film composites for high dielectric strength, deposited by pulsed direct current and radio frequency magnetron sputtering Thumbnail


Authors

Benjamin V.T. Hanby

Bryan W. Stuart

Jonathan Moffat

DAVID GRANT DAVID.GRANT@NOTTINGHAM.AC.UK
Professor of Materials Science



Abstract

Multilayer thin films have the potential to act as high dielectric strength insulation for wire and microelectronics. In this study, films consisting of 2, 4 or 8 layers, composed of Al2O3 with SiO2 or Ta2O5, were prepared via pulsed direct current and radio frequency magnetron sputtering to a thickness of between 152 and 236 nm. The dielectric strengths of all films exceeded the 310 Vμm−1 achieved for PDC Al2O3. Maximum dielectric strengths were obtained for four layer composites; Al2O3-SiO2-Al2O3-SiO2 (466 Vμm−1) and Al2O3-Ta2O5-Al2O3-Ta2O5 (513 Vμm−1), each containing two PDC-Al2O3 and two RF-SiO2/Ta2O5 layers. Whilst the average dielectric strength was higher in the Ta2O5 composites, they suffered from higher leakage prior to breakdown with ca. 6.5 nA compared to ca. 0.1 nA for SiO2 composites. The mechanical properties of the composites were poorer due to increased intrinsic coating stress. Samples exhibited complete interfacial delamination with maximum coating adhesion strengths of 22 and 25 MPa. The variance resulted from larger coefficient of thermal expansion for Ta2O5 compared to SiO2. Sputtered composites of Al2O3 and either SiO2 or Ta2O5 had high breakdown strength with reasonable adhesion and could be suitable for insulating copper conductors in the aerospace and automotive industries.

Citation

Hanby, B. V., Stuart, B. W., Gimeno-Fabra, M., Moffat, J., Gerada, C., & Grant, D. M. (2019). Layered Al2O3-SiO2 and Al2O3-Ta2O5 thin-film composites for high dielectric strength, deposited by pulsed direct current and radio frequency magnetron sputtering. Applied Surface Science, 492, 328-336. https://doi.org/10.1016/j.apsusc.2019.06.202

Journal Article Type Article
Acceptance Date Jun 20, 2019
Online Publication Date Jun 21, 2019
Publication Date Oct 30, 2019
Deposit Date Jul 1, 2019
Publicly Available Date Mar 29, 2024
Journal Applied Surface Science
Print ISSN 0169-4332
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 492
Pages 328-336
DOI https://doi.org/10.1016/j.apsusc.2019.06.202
Keywords Magnetron sputtering; Multilayers; Dielectric strength; Adhesion; Insulation
Public URL https://nottingham-repository.worktribe.com/output/2247360
Publisher URL https://www.sciencedirect.com/science/article/pii/S016943321931918X
Additional Information This article is maintained by: Elsevier; Article Title: Layered Al2O3-SiO2 and Al2O3-Ta2O5 thin-film composites for high dielectric strength, deposited by pulsed direct current and radio frequency magnetron sputtering; Journal Title: Applied Surface Science; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.apsusc.2019.06.202; Content Type: article; Copyright: © 2019 The Authors. Published by Elsevier B.V.

The authors would like to thank the Nanoscale and Microscale Research Centre (nmRC) for providing access to instrumentation. This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/LO22494/1]. The authors also wish to acknowledge the support of the beacon in Propulsion Futures and the Institute for Aerospace Technology at the University of Nottingham.

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