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Proceedings Paper

Micromachined capacitive electret microphone
Author(s): Christiane Thielemann; Gisela Hess
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Paper Abstract

Silicon-based electret materials are presented for the application in micro-machined sensors. Various dielectric layer systems of silicon dioxide and silicon nitride are investigated and compared to the well known single layer silicon dioxide. The superior material system silicon dioxide/silicon nitride is optimized in terms of charge stability, mechanical behavior and processing capabilities. Only the advantageous combination of low stress and good electret properties allows the realization of electret membranes for silicon microphones. Electret membranes were realized by means of an anisotropic etch process. Various measurements of charge stability were performed and evaluated. For the first time the application of an inorganic electret membrane in a micro-machined capacitive silicon microphone is presented and results are shown. An equivalent noise level of 32 dB could be achieved for an electret microphone with a 4 mm2 membrane area.

Paper Details

Date Published: 10 March 1999
PDF: 9 pages
Proc. SPIE 3680, Design, Test, and Microfabrication of MEMS and MOEMS, (10 March 1999); doi: 10.1117/12.341269
Show Author Affiliations
Christiane Thielemann, Fachhochschule Frankfurt am Main (Germany)
Gisela Hess, Technical Univ. of Darmstadt (Germany)

Published in SPIE Proceedings Vol. 3680:
Design, Test, and Microfabrication of MEMS and MOEMS
Bernard Courtois; Wolfgang Ehrfeld; Selden B. Crary; Wolfgang Ehrfeld; Hiroyuki Fujita; Jean Michel Karam; Karen W. Markus, Editor(s)

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