Dielectric breakdown of alumina thin films produced by pulsed direct current magnetron sputtering

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

Abstract

Alumina films (~2 μm thick) were deposited with a mixed Cu/Al interlayer onto copper. Direct current (DC)/Pulsed DC (PDC) magnetron sputtering techniques were independently compared for reactive alumina sputtering. In DC sputtered films, elemental aluminium of 9.2 at.% and nano-crystallites were present within the x-ray amorphous matrix, resulting from target arcing. Defects lead to premature dielectric breakdown/increased current leakage. PDC sputtering improved film quality by removing crystallites, metallic clusters and through thickness cracking. Time dependent dielectric breakdown (TDDB) measurements were carried out using conductive atomic force microscopy identified an improvement in dielectric strength (166 to 310 V μm−1) when switching from DC to PDC deposition power. TDDB suggested that at high applied field the dominant pre-breakdown conduction mechanism was Fowler-Nordheim tunnelling in DC films. Tensile pull-off adhesion ranged from 56 to 72 MPa and was highest following incorporation of an Cu/Al blended interfacial layer. Scratch testing indicated various cracking/buckling failures.

Citation

Hanby, B. V., Stuart, B. W., Grant, C., Moffat, J., Blissett, J., Gerada, C., Gimeno-Fabra, M., & Grant, D. M. (2018). Dielectric breakdown of alumina thin films produced by pulsed direct current magnetron sputtering. Thin Solid Films, 662, 145-154. https://doi.org/10.1016/j.tsf.2018.07.004

• Journal Article Type: Article
• Acceptance Date: Jul 4, 2018
• Online Publication Date: Jul 5, 2018
• Publication Date: Sep 30, 2018
• Deposit Date: Aug 8, 2018
• Publicly Available Date: Aug 8, 2018
• Journal: Thin Solid Films
• Print ISSN: 0040-6090
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 662
• Pages: 145-154
• DOI: https://doi.org/10.1016/j.tsf.2018.07.004
• Keywords: Alumina; Magnetron sputtering; Pulsed; Dielectric strength; Adhesion
• Public URL: https://nottingham-repository.worktribe.com/output/973034
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0040609018304590
• Additional Information: This article is maintained by: Elsevier; Article Title: Dielectric breakdown of alumina thin films produced by pulsed direct current magnetron sputtering; Journal Title: Thin Solid Films; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.tsf.2018.07.004; Content Type: article; Copyright: © 2018 The Authors. Published by Elsevier B.V.
• Contract Date: Aug 8, 2018