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Strength of Surface Micromachined Diaphragms

Published online by Cambridge University Press:  10 February 2011

Xing Yang
Affiliation:
Caltech Micromachining Laboratory, 136-93, Electrical Engineering California Institute of Technology, Pasadena, CA 91125, [email protected]
Frances M. Siu
Affiliation:
Caltech Micromachining Laboratory, 136-93, Electrical Engineering California Institute of Technology, Pasadena, CA 91125
Yu-Chong Tai
Affiliation:
Caltech Micromachining Laboratory, 136-93, Electrical Engineering California Institute of Technology, Pasadena, CA 91125
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Abstract

This paper presents the study of the strength of surface micromachined diaphragms. It is found that the diaphragm strength strongly depends on the diaphragm boundary conditions. A new fabrication technique which does not change the mask and fabrication process is proposed to improve the common step-up boundary condition. Test diaphragms with diameters from 200 µm to 800 µm and three different boundary conditions have been fabricated using silicon nitride/PSG and silicon nitride/polysilicon surface micromachining processes. Experimentally, it is found that the strength of the diaphragms is significantly improved with the new boundary conditions. The application of this technique to other surface micromachined structures is also described.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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