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Author: Dean, T. ×

Publications Search Results

Now showing 1 - 6 of 6
  • Publication
    Investigations of the impact of initial stresses on fracture and delamination risks of an avionics MEMS pressure sensor
    ( 2018)
    Auersperg, Jürgen
    ;
    Auerswald, E.
    ;
    Collet, C.
    ;
    Dean, T.
    ;
    Vogel, D.
    ;
    Winkler, T.
    ;
    Rzepka, Sven
    Silicon based pressure sensors often take advantage of piezo-resistive gages which are normally embedded by multiple silicon oxide and silicon nitride layers where gold lines form a Wheatstone bridge (Meti et al., 2016; Bae et al., 2004 [2]). Because of manufacturing - stepwise deposition of multiple layers - significant layer residual stresses occur in the GPa range in tension and compression (Zhou et al., 2017 [3]). But also anodic bonding of the silicon MEMS device on usually glassy substrates results in additional initial stresses (Chou et al., 2009 [4] and Sandvan et al. [5]). Especially in avionics MEMS applications such stresses by far exceed the stresses arising under sensor operation and determine the major risks for cracking and delamination. Furthermore, those stresses could lead to a signal drift of the overall sensor over a long period of time - another important trustworthiness risk (Espinosa and Prorok, 2003 [6]).
  • Publication
    Effects of residual stresses on cracking and delamination risks of an avionics MEMS pressure sensor
    ( 2017)
    Auersperg, Jürgen
    ;
    Auerswald, E.
    ;
    Collet, C.
    ;
    Dean, T.
    ;
    Vogel, D.
    ;
    Winkler, T.
    ;
    Rzepka, Sven
    Silicon based pressure sensors often take advantage of piezo-resistive gages which are normally embedded by multiple silicon oxide and silicon nitride layers where gold lines form a Wheatstone bridge. As a result of manufacturing - stepwise deposition of multiple layers - significant layer residual stresses occur in the GPa range in tension and compression. But also anodic bonding of the silicon MEMS device on usually glassy substrates results in additional initial stresses. Especially in avionics MEMS applications such stresses by far exceed the stresses arising under sensor operation and determine the major risks for cracking and delamination. Furthermore, those stresses could lead to a signal drift of the overall sensor over a long period of time - another important trustworthiness risk.
  • Publication
    Effects of residual stresses on cracking and delamination risks of an avionics MEMS pressure sensor
    ( 2016)
    Auersperg, Jürgen
    ;
    Collet, C.
    ;
    Dean, T.
    ;
    Vogel, D.
    ;
    Winkler, T.
    Silicon based pressure sensors often take advantage of piezo-resistive gages which are normally embedded by multiple silicon oxide and silicon nitride layers where gold lines form a Wheatstone bridge. As a result of manufacturing - stepwise deposition of multiple layers - significant layer residual stresses in the GPa range occur in tension and compression. Especially in avionics MEMS applications such stresses determine the major risks for cracking and delamination. To overcome the related reliability issues the authors performed experiments and nonlinear FEM-simulations. Basic information about the residual stresses in the gage stack were captured by a Focused Ion Beam (FIB) trench technique combined with digital image correlation. These results enriched the data base for finite element studies with the ABAQUSTM. Especially delamination risks were investigated by a surface based cohesive contact approach which simulates the initiation and propagation of damage and cracking within and underneath the gage layer. The cracking risk is investigated by means of an Extended Finite Element Method (XFEM). Both, crack initiation location as well as crack path are results of XFEM simulations. Several design variations have been investigated and compared to give insights to potential crack initiation sites and to evaluate the risk of fracture during processing.
  • Publication
    Analysis of active micromembranes with nanometer resolution
    ( 2004)
    Aswendt, P.
    ;
    Dean, T.
    The paper describes methodology, instrumentation, and experiments for the study of the mechanical behaviour of MEMS, especially active micromembranes. The technique of speckle interferometry is extended to high microscopic magnification and short wavelength of laser light. Micromembrane arrays different in size and shape were analysed with respect to plezo response, resonance, and cross-talk. Challenging issues for the optical measurement are the micrometer lateral size of the details, the nanometer deflection, and the Megahertz frequencies of resonant vibrations.
  • Publication