Files

No attached file found for this publication.

Details

Authors
Abstract
A new testing method based on an on-chip concept has been developed to measure the fracture toughness of freestanding submicron films. Fracture mechanics models have been developed to address various types of crack configurations occurring in thin films on substrates. These models have been applied to a wide range of systems, providing relevant fracture toughness data that are important for the design and integrity assessment of coatings and microelectronics applications, for instance. Still, it is sometimes very complicated to deconvolute the constraint exerted by the substrate on the cracked film especially when it involves viscoelastic or plastic deformation. Furthermore, freestanding films allow, if sufficiently thin, direct observation in transmission electron microscopy (TEM) of the fracture mechanisms. The design of this new test configuration consists of two long actuator beams undergoing large internal stress. A specimen is attached to these two actuators, incorporating a notch patterned by means of e-beam lithography. The geometry resembles a double cantilever beam geometry classically used in fracture mechanics testing. At the start, both actuators and specimen lie on a sacrificial layer. Nothing happens. A chemical release step is then performed through the etching of the sacrificial layer. During the release of the test structure, the actuators contract, pulling then on the specimen. A crack is initiated from the notch tip, propagates and finally stops after the energy release rate decreases down to its critical value. This is a crack arrest measurement. For the sake of a proof of concept, 55 nm thick silicon nitride films were successfully tested using this new method. Analytical equations that describe the stress intensity factor (energy release rate) were developed and assessed towards finite element analysis (FE). The experimental results lead to a fracture toughness of these SiN films between 1.6- 1.73"[GPa" √μm "]" .
Affiliations

Citations

  • APA
  • Chicago
  • FWB

Jaddi, S., Coulombier, M., Raskin, J.-P., Pardoen, T., & et al. (2018). On a chip fracture mechanics test method. Proceedings of the 16th European Mechanics of Materials Conference EMMC16. Published. 16th European Mechanics of Materials Conference EMMC16, Nantes. https://hdl.handle.net/2078.5/226830