Capacitive Silicon Microphone

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

doi:10.1238/Physica.Topical.079a00275

Capacitive Silicon Microphone

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

Research output: Contribution to journal › Article in a proceedings journal › Scientific › peer-review

2 Citations (Scopus)

Abstract

A capacitive silicon microphone has been fabricated. The component consists of two freestanding polysilicon membranes, a low-stress bending membrane and a high-stress backplate, which are separated by an air gap. Sound pressure changes the capacitance between the membranes. A back-chamber is arranged by encapsulation and static pressure changes are prevented with small equalisation holes in the bending membrane. The component is fabricated combining bulk and surface micromachining techniques. Silicon substrates are etched in TMAH and sacrificial oxide between the membranes is etched in PSG-etch followed by freeze drying to prevent sticking. The measured acoustic sensitivity of the microphone with 1 × 1 mm² membrane was 2mV/Pa (1 kHz frequency) and the resolution 35 dB (A-weighted sound level).

Original language	English
Pages (from-to)	275-278
Number of pages	4
Journal	Physica Scripta: Topical Issues
DOIs	https://doi.org/10.1238/Physica.Topical.079a00275
Publication status	Published - 1 Dec 1999
MoE publication type	A4 Article in a conference publication
Event	18th Nordic Semiconductor Meeting, NSM18 - Linköping, Sweden Duration: 8 Jun 1998 → 10 Jun 1998

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10.1238/Physica.Topical.079a00275

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title = "Capacitive Silicon Microphone",

abstract = "A capacitive silicon microphone has been fabricated. The component consists of two freestanding polysilicon membranes, a low-stress bending membrane and a high-stress backplate, which are separated by an air gap. Sound pressure changes the capacitance between the membranes. A back-chamber is arranged by encapsulation and static pressure changes are prevented with small equalisation holes in the bending membrane. The component is fabricated combining bulk and surface micromachining techniques. Silicon substrates are etched in TMAH and sacrificial oxide between the membranes is etched in PSG-etch followed by freeze drying to prevent sticking. The measured acoustic sensitivity of the microphone with 1 × 1 mm2 membrane was 2mV/Pa (1 kHz frequency) and the resolution 35 dB (A-weighted sound level).",

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AU - Torkkeli, Altti

AU - Saarilahti, Jaakko

AU - Seppä, Heikki

AU - Sipola, Hannu

AU - Rusanen, Outi

AU - Hietanen, Jarmo

PY - 1999/12/1

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N2 - A capacitive silicon microphone has been fabricated. The component consists of two freestanding polysilicon membranes, a low-stress bending membrane and a high-stress backplate, which are separated by an air gap. Sound pressure changes the capacitance between the membranes. A back-chamber is arranged by encapsulation and static pressure changes are prevented with small equalisation holes in the bending membrane. The component is fabricated combining bulk and surface micromachining techniques. Silicon substrates are etched in TMAH and sacrificial oxide between the membranes is etched in PSG-etch followed by freeze drying to prevent sticking. The measured acoustic sensitivity of the microphone with 1 × 1 mm2 membrane was 2mV/Pa (1 kHz frequency) and the resolution 35 dB (A-weighted sound level).

AB - A capacitive silicon microphone has been fabricated. The component consists of two freestanding polysilicon membranes, a low-stress bending membrane and a high-stress backplate, which are separated by an air gap. Sound pressure changes the capacitance between the membranes. A back-chamber is arranged by encapsulation and static pressure changes are prevented with small equalisation holes in the bending membrane. The component is fabricated combining bulk and surface micromachining techniques. Silicon substrates are etched in TMAH and sacrificial oxide between the membranes is etched in PSG-etch followed by freeze drying to prevent sticking. The measured acoustic sensitivity of the microphone with 1 × 1 mm2 membrane was 2mV/Pa (1 kHz frequency) and the resolution 35 dB (A-weighted sound level).

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