Capacitive microphone with low-stress polysilicon membrane and high-stress polysilicon backplate

Altti Torkkeli, Outi Rusanen, Jaakko Saarilahti, Heikki Seppä, Hannu Sipola, Jarmo Hietanen

Research output: Contribution to journalArticleScientificpeer-review

72 Citations (Scopus)

Abstract

A capacitive single-chip silicon microphone with very low-stress polysilicon membrane was fabricated. A mechanism for stress-releasing due to the high stress of the perforated membrane was introduced. With the achieved stress level of 2 MPa, a microphone with the membrane area of 1 mm2 can be optimally designed, although the measured components did not show the optimal resolution due to excessive acoustic resistance. With a membrane area of 1 mm2, the acoustical sensitivity was 4 mV/Pa (at 1 kHz) and the noise equivalent sound level was 33.5 dB (A), which are adequate values for many applications. The packaged components were tested with a thermal cycle between -40 °C and +60 °C, and due to low packaging-related stresses, no buckling of the membranes was observed.

Original languageEnglish
Pages (from-to)116-123
JournalSensors and Actuators A: Physical
Volume85
Issue number1
DOIs
Publication statusPublished - 25 Aug 2000
MoE publication typeA1 Journal article-refereed

Fingerprint

Microphones
microphones
Polysilicon
membranes
Membranes
acoustics
releasing
Silicon
buckling
Acoustic noise
packaging
Buckling
Packaging
Acoustics
chips
Acoustic waves
cycles
sensitivity
silicon

Keywords

  • capacitive
  • microphone
  • polysilicon
  • stress

Cite this

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abstract = "A capacitive single-chip silicon microphone with very low-stress polysilicon membrane was fabricated. A mechanism for stress-releasing due to the high stress of the perforated membrane was introduced. With the achieved stress level of 2 MPa, a microphone with the membrane area of 1 mm2 can be optimally designed, although the measured components did not show the optimal resolution due to excessive acoustic resistance. With a membrane area of 1 mm2, the acoustical sensitivity was 4 mV/Pa (at 1 kHz) and the noise equivalent sound level was 33.5 dB (A), which are adequate values for many applications. The packaged components were tested with a thermal cycle between -40 °C and +60 °C, and due to low packaging-related stresses, no buckling of the membranes was observed.",
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Capacitive microphone with low-stress polysilicon membrane and high-stress polysilicon backplate. / Torkkeli, Altti; Rusanen, Outi; Saarilahti, Jaakko; Seppä, Heikki; Sipola, Hannu; Hietanen, Jarmo.

In: Sensors and Actuators A: Physical, Vol. 85, No. 1, 25.08.2000, p. 116-123.

Research output: Contribution to journalArticleScientificpeer-review

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AU - Torkkeli, Altti

AU - Rusanen, Outi

AU - Saarilahti, Jaakko

AU - Seppä, Heikki

AU - Sipola, Hannu

AU - Hietanen, Jarmo

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AB - A capacitive single-chip silicon microphone with very low-stress polysilicon membrane was fabricated. A mechanism for stress-releasing due to the high stress of the perforated membrane was introduced. With the achieved stress level of 2 MPa, a microphone with the membrane area of 1 mm2 can be optimally designed, although the measured components did not show the optimal resolution due to excessive acoustic resistance. With a membrane area of 1 mm2, the acoustical sensitivity was 4 mV/Pa (at 1 kHz) and the noise equivalent sound level was 33.5 dB (A), which are adequate values for many applications. The packaged components were tested with a thermal cycle between -40 °C and +60 °C, and due to low packaging-related stresses, no buckling of the membranes was observed.

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