Development of an electret microphone in silicon

A.J. Sprenkels, R.A. Groothengel, A.J. Verloop, P. Bergveld

Research output: Contribution to journalArticleAcademic

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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.
Original languageEnglish
Pages (from-to)509-512
JournalSensors and actuators
Volume17
Issue number3-4
DOIs
Publication statusPublished - 1989

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Electrets
Microphones
Diaphragms
Silicon
Air
Silicon wafers
Polyethylene terephthalates
Metal foil
Electric fields
Networks (circuits)
Processing

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Sprenkels, A. J., Groothengel, R. A., Verloop, A. J., & Bergveld, P. (1989). Development of an electret microphone in silicon. Sensors and actuators, 17(3-4), 509-512. https://doi.org/10.1016/0250-6874(89)80038-1
Sprenkels, A.J. ; Groothengel, R.A. ; Verloop, A.J. ; Bergveld, P. / Development of an electret microphone in silicon. In: Sensors and actuators. 1989 ; Vol. 17, No. 3-4. pp. 509-512.
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Sprenkels, AJ, Groothengel, RA, Verloop, AJ & Bergveld, P 1989, 'Development of an electret microphone in silicon' Sensors and actuators, vol. 17, no. 3-4, pp. 509-512. https://doi.org/10.1016/0250-6874(89)80038-1

Development of an electret microphone in silicon. / Sprenkels, A.J.; Groothengel, R.A.; Verloop, A.J.; Bergveld, P.

In: Sensors and actuators, Vol. 17, No. 3-4, 1989, p. 509-512.

Research output: Contribution to journalArticleAcademic

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Sprenkels AJ, Groothengel RA, Verloop AJ, Bergveld P. Development of an electret microphone in silicon. Sensors and actuators. 1989;17(3-4):509-512. https://doi.org/10.1016/0250-6874(89)80038-1