Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 53: Topical Session: Fundamentals of Fracture - Novel Experimental Techniques II

MM 53.3: Talk

Thursday, March 14, 2013, 12:15–12:30, H4

Bulge testing as a tool for investigating the fracture properties of thin films - Application to silicon nitride and gold membranes — •Benoit Merle and Mathias Göken — Department of Materials Science and Engineering, Institute I, University Erlangen-Nürnberg, Germany

The bulge test was developed into a valuable tool for investigating the fracture mechanism of very thin films (30 - 300 nm). The improved sample preparation includes milling a crack-like slit in the center of the membrane, using a Focused Ion Beam. The samples are then pressurized in the bulge test until failure occurs. Optionally, the experimental setup is inserted into an AFM, which allows in-situ imaging of the extension of the crack. The presentation will show applications on thin amorphous silicon nitride and nanocrystalline gold films. As a brittle material, silicon nitride is well suited for the quantitative measurement of the fracture toughness KIC. The bulge test results show that the fracture toughness does not depend on the thickness of the SiNx film, although its state changes from plane-strain to plane-stress. Since gold is a more ductile material, the focus was laid on the in-situ AFM observations of the crack propagation. Grain boundary sliding was observed to occur in these thin films, which probably accounts for the low toughness found for gold thin films.