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

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

Research output: Journal PublicationArticlepeer-review

8 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)145-154
Number of pages10
JournalThin Solid Films
Publication statusPublished - 30 Sept 2018


  • Adhesion
  • Alumina
  • Dielectric strength
  • Magnetron sputtering
  • Pulsed

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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