Measuring the fracture toughness of ultra-thin films with application to AlTa coatings

Yong XIANG, James MCKINNELL, Wie Ming ANG, Joost J. VLASSAK*

*Corresponding author for this work

Research output: Journal PublicationsJournal Article (refereed)peer-review

24 Citations (Scopus)


An experimental technique is presented for measuring the fracture toughness of brittle thin films. In this technique, long rectangular membranes are fabricated from the film of interest using standard silicon micromachining techniques. A focused ion beam is then used to introduce pre-cracks of different lengths along the centerline of the membranes and the membranes are pressurized until rupture. The fracture stress of the membrane is measured as a function of pre-crack length and the fracture toughness of the film is determined from a simple fracture mechanics analysis. The technique is applicable to a wide range of materials and is especially suited for ultra-thin films. We have demonstrated the experimental procedure for a 150 nm AlTa intermetallic film and obtained a room-temperature fracture toughness of K1c = 4.44 ± 0.21 MPam1/2.

Original languageEnglish
Pages (from-to)173-179
Number of pages7
JournalInternational Journal of Fracture
Issue number3
Publication statusPublished - Apr 2007
Externally publishedYes

Bibliographical note

The work presented in this paper was funded by Hewlett-Packard and by the National Science Foundation under grant DMR-0133559.


  • Bulge test
  • Fracture toughness
  • Thin films


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