Deformation of large micro-electromechanical systems (MEMS) due to thermal and intrinsic stresses

Mohammed T.A. Saif; Noel C. MacDonald

doi:10.1117/12.209803

22 May 1995 Deformation of large micro-electromechanical systems (MEMS) due to thermal and intrinsic stresses

Mohammed T.A. Saif, Noel C. MacDonald

Proceedings Volume 2441, Smart Structures and Materials 1995: Smart Materials; (1995) https://doi.org/10.1117/12.209803
Event: Smart Structures and Materials '95, 1995, San Diego, CA, United States

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.

Citation Download Citation

Mohammed T.A. Saif and Noel C. MacDonald "Deformation of large micro-electromechanical systems (MEMS) due to thermal and intrinsic stresses", Proc. SPIE 2441, Smart Structures and Materials 1995: Smart Materials, (22 May 1995); https://doi.org/10.1117/12.209803

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