Patterned bilayer plate microstructures subjected to thermal loading: Deformation and stresses

INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES

卷:46

Article

Zhang, Yanhang^1,2  Dunn, Martin L.³ 

[1] Boston Univ, Dept Mech Engn, Boston, MA 02215 USA

[2] Boston Univ, Dept Biomed Engn, Boston, MA 02215 USA

[3] Univ Colorado, Dept Mech Engn, Boulder, CO 80309 USA

关键词: Patterned plate microstructures;    Micro-electro-mechanical systems (MEMS);    Thermomechanical deformation;    Stress;    Curvature;    Geometric nonlinearity;    Generalized plane strain;    Finite element method;   

DOI  :  10.1016/j.ijsolstr.2008.08.020

来源: Elsevier

【 摘 要 】

We studied the deformation of a series of gold/polysilicon patterned plate microstructures fabricated by surface micromachining. The patterned plate microstructures were subjected to a uniform temperature change from 100 degrees C to room temperature that was intended to induce linear and geometrically nonlinear deformation. We used interferometry to measure full-field deformed shapes of the microstructures. From these measurements we determined the spatially-averaged curvature of the deformed microstructures within individual lines and across the entire plate. The deformation response of the patterned plates can be broadly characterized in terms of the average curvature as a function of temperature change and exhibits linear and geometrically nonlinear behavior. We modeled the deformation response of the patterned plates using geometrically nonlinear plate theory with the finite element method. Good agreement was obtained between predictions and measurements for both local curvature variations across lines and for the evolution of curvature of the entire plate with temperature change. Using a generalized plane strain approach with the finite element method we also modeled the spatial dependence of the stress distribution in the lines and substrate. For thick plates, our results agree with those of previous studies, showing a decrease in the von Mises stress in the metal lines with decreasing linewidth. For thinner substrates, though, we find the behavior with linewidth is opposite and there is a critical substrate thickness (about 10 mu m for the system in our Study) where the behavior with linewidth changes. These results have important implications in the design of patterned structures for micro-electro-mechanical systems (MEMS) applications where films are of comparable thickness to the underlying substrate. Published by Elsevier Ltd.

【 授权许可】

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