Micromachined capacitive electret microphone

Christiane Thielemann; Gisela Hess

doi:10.1117/12.341269

10 March 1999 Micromachined capacitive electret microphone

Christiane Thielemann, Gisela Hess

Proceedings Volume 3680, Design, Test, and Microfabrication of MEMS and MOEMS; (1999) https://doi.org/10.1117/12.341269
Event: Design, Test, and Microfabrication of MEMS/MOEMS, 1999, Paris, France

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.

Citation Download Citation

Christiane Thielemann and Gisela Hess "Micromachined capacitive electret microphone", Proc. SPIE 3680, Design, Test, and Microfabrication of MEMS and MOEMS, (10 March 1999); https://doi.org/10.1117/12.341269

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