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Proceedings Paper

2D simulation of multilayered MEMS structures
Author(s): Prakash R. Apte; Saurabh A. Chandorkar; Prasanna S. Gandhi
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Paper Abstract

MEMS device structures, particularly those made using Surface-Micromachining, consist of thin layers of insulator, silicon, silicon dioxide, silicon nitride, metal or poly-silicon held at few points onto a thick silicon substrate. These heterogeneous layers resemble closely to laminas of composites used in building structures. For these heterogeneous material systems, involving Metal-Insulator-Semiconductor layers, there is usually an inherent two dimensional thermal contraction of the various layers upon cooling from a growth temperature of 1000 to 1200 C down to room temperature. The thermal stress, so developed, could result in static deformation as well change the dynamic characteristics of the micro-parts. Thin heteroepitaxial layers, with lattice mismatch with the single crystal substrate, can also result in a built in stress. External effects like electrostatic potentials and magnetic fields applied to a layered structure can also result in contractions or extensions of specific layers that respond to applied fields. A generic formulation of governing equations of equilibrium and compatibility has been developed for laminated structures with various in-built stress effects like difference in temperature of formation and use; difference in lattice constants of heteroepitaxial layers; effects that involve dimensional changes like piezoelectric effect and magnetostriction. This paper aims at demonstrating, through simulations of a test structure of a doubly suspended resonator, how these multi-layer structures could exploit the static deformations to result in a robust (temperature-insensitive) dynamic response. The static deformation for temperature changes in a bi-layer of aluminum and silicon dioxide is simulated on ANSYS. The results of ANSYS match very well with a fabricated test device.

Paper Details

Date Published: 14 October 2003
PDF: 12 pages
Proc. SPIE 5062, Smart Materials, Structures, and Systems, (14 October 2003); doi: 10.1117/12.514905
Show Author Affiliations
Prakash R. Apte, Indian Institute of Technology, Mumbai (India)
Saurabh A. Chandorkar, Indian Institute of Technology, Mumbai (India)
Prasanna S. Gandhi, Indian Institute of Technology, Mumbai (India)

Published in SPIE Proceedings Vol. 5062:
Smart Materials, Structures, and Systems
S. Mohan; B. Dattaguru; S. Gopalakrishnan, Editor(s)

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