Determining the stress-strain behaviour of small devices by nanoindentation in combination with inverse methods

S. Stauss, P. Schwaller, J. L. Bucaille, R. Rabe, L. Rohr, J. Michler, E. Blank

Research output: Contribution to journalConference articlepeer-review

48 Citations (Scopus)

Abstract

The ongoing miniaturisation of thin films, coatings, micro-electromechanical systems (MEMS) components and devices demands for new characterising tools and methods. Conventional mechanical tests cannot be readily applied to small scales, first because one can expect new mechanical properties of such small-scale materials and second because minuscule samples are difficult to handle in conventional mechanical experiments such as tensile tests. Here we present a new method for determining the mechanical properties of LIGA (German acronym for 'Lithographie, Galvanoformung und Abformung') processed MEMS, mechanical watch parts and devices. The method is based on a reverse analysis of load-displacement data obtained from nanoindentation experiments that can be performed on micrometer sized volumes. To validate the method for typical applications in microengineering, a comparison of microtensile and nanoindentation tests is presented in this paper. The comparison of microtensile and nanoindentation tests showed that the elastic modulus obtained in nanoindentation for all tested materials was systematically about 15% higher than the values obtained in tensile testing, which can be attributed to the different size and microstructural levels that are probed. The numerical simulation of the nanoindentation tests allowed to estimate the true stress-true strain relationship up to strain levels of 30%, whereas in microtensile experiments the rheology of the tested materials can be determined to 5% only.

Original languageEnglish
Pages (from-to)818-825
Number of pages8
JournalMicroelectronic Engineering
Volume67-68
DOIs
Publication statusPublished - 2003 Jun
Externally publishedYes
EventProceedings of the 28th International Conference on MNE - Lugano, Switzerland
Duration: 2002 Sep 162002 Sep 19

Keywords

  • Finite-element simulation
  • Inverse method
  • LIGA process
  • Mechanical properties
  • Nanoindentation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering

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