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Konetschnik R.,University of Leoben | Daniel R.,University of Leoben | Brunner R.,Material Center Leoben Forschungs GmbH | Kiener D.,University of Leoben
AIP Advances | Year: 2017

Driven by the ongoing miniaturization and increasing integration in microelectronics devices, very thin metallic films became ever more important in recent years. Accordingly also the capability of determining specific physical and mechanical properties of such arrangements gained increasing importance. Miniaturized testing methods to evaluate, for example, the mechanical properties of thin metallic multilayers are therefore indispensable. A novel in-situ micromechanical approach is examined in the current study and compared to existing methods regarding their capability to determine the interface toughness of specific interfaces in multilayer configurations. Namely, sputter deposited copper and tungsten thin films with a thickness of approx. 500 nm on a stress-free silicon (100) substrate are investigated. The multilayer stacks consist of different materials that vary in microstructure, elastic properties and residual stress state. We examine the interface toughness via double cantilever beam tests, nanoindentation and novel miniaturized shear tests. The choice of a proper test method is indispensable when addressing strong interfaces, such as the W-Cu interface, in the presence of weaker ones. Finally, it is demonstrated that miniaturized shear testing is a very promising approach to test such strong interfaces as the interface of interest to fail is predefined by the sample geometry. © 2017 Author(s).

Abboud A.,University of Siegen | Kirchlechner C.,Max Planck Institute Für Eisenforschung | Kirchlechner C.,University of Leoben | Send S.,University of Siegen | And 7 more authors.
Review of Scientific Instruments | Year: 2014

μLaue diffraction with a polychromatic X-ray beam can be used to measure strain fields and crystal orientations of micro crystals. The hydrostatic strain tensor can be obtained once the energy profile of the reflections is measured. However, this remains a challenge both on the time scale and reproducibility of the beam position on the sample. In this review, we present a new approach to obtain the spatial and energy profiles of Laue spots by using a pn-junction charge-coupled device, an energy-dispersive area detector providing 3D resolution of incident X-rays. The morphology and energetic structure of various Bragg peaks from a single crystalline Cu micro-cantilever used as a test system were simultaneously acquired. The method facilitates the determination of the Laue spots' energy spectra without filtering the white X-ray beam. The synchrotron experiment was performed at the BM32 beamline of ESRF using polychromatic X-rays in the energy range between 5 and 25 keV and a beam size of 0.5 μm x 0.5 μm. The feasibility test on the well known system demonstrates the capabilities of the approach and introduces the "3D detector method" as a promising tool for material investigations to separate bending and strain for technical materials. © 2014 AIP Publishing LLC.

Treml R.,University of Leoben | Kozic D.,Material Center Leoben Forschungs GmbH | Schongrundner R.,Material Center Leoben Forschungs GmbH | Kolednik O.,Austrian Academy of Sciences | And 3 more authors.
Extreme Mechanics Letters | Year: 2016

Recently, the miniaturization of devices in the field of microelectronics has become more and more important. This also implies an increased complexity of the devices, where multilayer thin film systems play a major role. The use of various material combinations leads to the development of residual stresses, potentially causing cracks. Therefore, to prevent failures a thorough understanding of material properties such as the fracture toughness at small scales is indispensable, as these may differ significantly from bulk values. In this study we use miniaturized fracture tests to investigate the fracture behaviour of Cu-W-Cu and W-Cu-W trilayer thin film systems, having a thickness of 500nm per individual W or Cu layer. The films are subjected to differences in elastic properties and residual stress gradients that both influence the fracture behaviour and thus have to be included in all considerations. We demonstrate that for the W layers a valid J-integral can be evaluated. However, we find that the presented advanced treatment does not allow the extraction of valid fracture mechanical quantities for the Cu layers, pointing out the need to develop a more sophisticated approach for ductile materials. © 2016 Elsevier Ltd.

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