Acoustic emission analysis of fracture events in Cu films with W overlayers

Alex A. Volinsky, William W. Gerberich

Research output: Contribution to journalConference articlepeer-review

6 Scopus citations


Indentation-induced delamination of thin films provides the basis for adhesion calculations. In the case of ductile Cu films plastic deformation usually prevents a film from debonding from the substrate. Deadhesion is facilitated by the use of a hard W superlayer, which promotes indenter-induced Cu film failure, increasing the delamination area by an order of magnitude. Radial as well as annular cracking acts like a secondary mechanism in the strain energy release, and can be resolved from excursions on the load-displacement curves. For the thicker Cu films no excursions were observed, though radial cracking took place. It is important to identify fracture events as they occur in order to understand the system behavior and accurately apply the analysis. An acoustic emission signal is used to detect the magnitude of fracture events in thin Cu films. For the films of different thickness from 40 nm to 3 microns the corresponding interfacial fracture energy ranged from 0.2 to over 100 J/m2. Limits of plastic energy dissipation are determined with the lower limit, the true work of adhesion, being associated with a dislocation emission criterion. Crack arrest marks were found upon the blister removal, and are proposed to represent the shape of the crack tip. Total acoustic emission energy was found to be inversely proportional to the strain energy release rate.

Original languageEnglish (US)
Pages (from-to)275-284
Number of pages10
JournalMaterials Research Society Symposium - Proceedings
StatePublished - 1999
EventProceedings of the 1999 MRS Spring Meeting - Symposium on 'Materials Reliability in Microelectronics IX' - San Francisco, CA, United States
Duration: Apr 6 1999Apr 8 1999


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