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

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

doi:10.1016/S0924-4247(00)00336-8

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 journal › Article › Scientific › peer-review

98 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 language	English
Pages (from-to)	116-123
Journal	Sensors and Actuators A: Physical
Volume	85
Issue number	1
DOIs	https://doi.org/10.1016/S0924-4247(00)00336-8
Publication status	Published - 25 Aug 2000
MoE publication type	A1 Journal article-refereed

Funding

The authors would like to thank the technical staff at VTT Electronics for processing and packaging the microphones and Jari Likonen from VTT Chemical technology for performing the SIMS measurements. The project was funded by TEKES, VTT, and the Finnish industry.

Keywords

capacitive
microphone
polysilicon
stress

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10.1016/S0924-4247(00)00336-8

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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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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KW - polysilicon

KW - stress

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

Abstract

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Keywords

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