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Proceedings Paper

Deformation of large micro-electromechanical systems (MEMS) due to thermal and intrinsic stresses
Author(s): Mohammed T.A. Saif; Noel C. MacDonald
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Paper Abstract

We present a theoretical and experimental study of large micro mechanical cantilever beams fabricated by the SCREAM (single crystal reactive ion etching and metallization) process. SCREAM beams consist of an SCS core coated by films of SiO2 or nitride and metal. Thermal and intrinsic stresses develop in the beams due to the films and tend to deform them. Such deformations result in non-planar structures. For small micro mechanical systems, the non-planarity is negligible. When the structures' size is of the order of few millimeters, the non-planarity may limit the performance of the device. Here, we first treat the thermal and intrinsic strains of the films as material properties and measure them experimentally for PECVD SiO2. We then develop a simple model to predict the deformation of cantilever beams due to the thermal and intrinsic strains of SiO2 or nitride film. The model predicts that the non-planarity of the beam can be controlled by properly choosing the cross sectional dimension of the beam. We validate the theoretical prediction by fabricating cantilever beams which deform with negative, positive, and almost zero curvature.

Paper Details

Date Published: 22 May 1995
PDF: 12 pages
Proc. SPIE 2441, Smart Structures and Materials 1995: Smart Materials, (22 May 1995); doi: 10.1117/12.209803
Show Author Affiliations
Mohammed T.A. Saif, Cornell Univ. (United States)
Noel C. MacDonald, Cornell Univ. (United States)

Published in SPIE Proceedings Vol. 2441:
Smart Structures and Materials 1995: Smart Materials
A. Peter Jardine, Editor(s)

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