An experimental/computational approach to identify moduli and residual stress in MEMS radio-frequency switches

H. D. Espinosa*, Y. Zhu, M. Fischer, J. Hutchinson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

In this paper, we identify the Young's modulus and residual stress state of a free-standing thin aluminum membrane, used in MEMS radio-frequency (rf) switches. We have developed a new methodology that combines a membrane deflection experiment (MDE) and three-dimensional numerical simulations. Wafer-level MDE tests were conducted with a commercially available nanoindenter. The accuracy and usefulness of the MDE is confirmed by the repeatability and uniformity of measured load-deflection curves on a number of switches with both wedge and Berkovich tips. It was found that the load-deflection behavior is a function of membrane elastic properties, initial residual stress state and corresponding membrane shape. Furthermore, it was assessed that initial membrane shape has a strong effect on load-deflection curves; hence, its accurate characterization is critical. Through an iterative process and comparison between MDE data and numerical simulations, the Young's modulus and residual stress state, consistent with measured membrane shape, were identified. One important finding from this investigation is that variations in membrane elastic properties and residual stress state affect the load-deflection curve in different regimes. Changes in residual stress state significantly affect the load-deflection slope at small values of deflection. By contrast, variations in Young's modulus result in changes in load-deflection slope at large deflections. These features are helpful to decouple both effects in the identification process.

Original languageEnglish (US)
Pages (from-to)309-316
Number of pages8
JournalExperimental Mechanics
Volume43
Issue number3
DOIs
StatePublished - Sep 2003

Keywords

  • MEMS
  • Moduli
  • Nanoindentation
  • Residual stress
  • Rf switch

ASJC Scopus subject areas

  • Mechanics of Materials
  • Computational Mechanics

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