Development of an electret microphone in silicon

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Sprenkels, A.J. and Groothengel, R.A. and Verloop, A.J. and Bergveld, P. (1989) Development of an electret microphone in silicon. Sensors and Actuators, 17 (3-4). pp. 509-512. ISSN 0250-6874

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Abstract:We describe a subminiature electret microphone, which has been realized in silicon using wafer processing techniques. The microphone consists of a rigid backplate fabricated in silicon and a 2.5 μm thick metallized Mylar foil (PETP) acting as the diaphragm. Between the diaphragm and the backplate a 20 μm thick air cavity and a 1.1 μm thick charged SiO2 layer are present. The SiO2 layer is used as the electret and generates an electric field in the air gap. The electret has been changed to 300 V using a corona-charging set-up. The time constant of the charge decay amounts to more than 100 years at ambient laboratory conditions.

The microphone cartridge, which measures 3 × 3 × 0.3 mm, shows an open-circuit sensitivity of about 2.5 mV/μbar at 1 kHz.
Item Type:Article
Copyright:© 1989 Elsevier Science
Faculty:
Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:
Link to this item:http://purl.utwente.nl/publications/70403
Official URL:http://dx.doi.org/10.1016/0250-6874(89)80038-1
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