Journal of Sensor Science and Technology (센서학회지)

The Korean Sensors Society (한국센서학회)
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Design and fabrication of condenser microphone with rigid backplate and vertical acoustic holes using DRIE and wafer bonding technology

기판접합기술을 이용한 두꺼운 백플레이트와 수직음향구멍을 갖는 정전용량형 마이크로폰의 설계와 제작

  • Kwon, Hyu-Sang (KRISS Division of Physical Metrology, Mechanical Metrology Group) ;
  • Lee, Kwang-Cheol (KRISS Division of Advanced Technology, Leading-Edge Technology Group)
  • 권휴상 (한국표준과학연구원 기반표준부 역학그룹) ;
  • 이광철 (한국표준과학연구원 전략기술연구부 미래신수요측정그룹)
  • Published : 2007.01.31
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Abstract

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin (Au/Sn) eutectic solder bonding. The membrane chip has 2.5 mm${\times}$2.5 mm, $0.5{\mu}m$ thick low stress silicon nitride membrane, 2 mm${\times}$2 mm Au/Ni/Cr membrane electrode, and $3{\mu}m$ thick Au/Sn layer. The backplate chip has 2 mm${\times}$2 mm, $150{\mu}m$ thick single crystal silicon rigid backplate, 1.8 mm${\times}$1.8 mm backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50-60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is $39.8{\mu}V/Pa$ (-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

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References

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