A bottom-inlet type MEMS acoustic sensor with wheel-shaped back-plate anchor

A bottom-inlet type micro-electro-mechanical system (MEMS) acoustic sensor with a wheel-shaped back-plate anchor is presented. Underneath the back-plate, the wheel-shape anchor is newly inserted to be adjusted to a fixed stator on a substrate. The 30 μm;-high back-plate anchor is patterned by deep reactive-ion etching (DRIE) and covered with a thick back-plate of 2.3 μm; thus, it can play an important role in protecting the foundations under the diaphragm anchors from other loads. Furthermore, structure-based equivalent circuit modeling for a capacitive-type MEMS acoustic sensor is implemented with a lumped model, which is subsequently divided into three main areas: acoustic, mechanical, and electrical domains. The acoustic sensor had an open-circuit sensitivity of -43.0 dBV/Pa at 1 kHz with a bias of 10.0 V, while the modeled open-circuit sensitivity was -42.7 dBV/Pa, which shows good agreement in the range from 100 Hz to 18 kHz. This demonstrates the validity of the structure-based equivalent circuit model for the prediction and design of the sensor.

[1]  Zhijian Li,et al.  Design and fabrication of silicon condenser microphone using corrugated diaphragm technique , 1996 .

[2]  J. Bergqvist,et al.  A silicon condenser microphone using bond and etch-back technology , 1994 .

[3]  T. Brosnihan,et al.  A MEMS Condenser Microphone for Consumer Applications , 2006, 19th IEEE International Conference on Micro Electro Mechanical Systems.

[4]  J. Bergqvist.  Finite-element modelling and characterization of a silicon condenser microphone with a highly perforated backplate , 1993 .

[5]  A. Ando,et al.  High-Performance Condenser Microphone With Single-Crystalline Silicon Diaphragm and Backplate , 2007, IEEE Sensors Journal.

[6]  Chi-Hoon Jun,et al.  Micromachined air-gap structure MEMS acoustic sensor using reproducible high-speed lateral etching and CMP process , 2006 .

[7]  Jun Ma,et al.  On the single-chip condenser miniature microphone using DRIE and backside etching techniques , 2003 .

[8]  Weileun Fang,et al.  Design and Implementation of a Capacitive-Type Microphone With Rigid Diaphragm and Flexible Spring Using the Two Poly Silicon Micromachining Processes , 2011, IEEE Sensors Journal.

[9]  H. Tilmans.  Equivalent circuit representation of electromechanical transducers: I. Lumped-parameter systems , 1996 .

[10]  Wouter Olthuis,et al.  A review of silicon microphones , 1994 .

[11]  M. Fuldner,et al.  Analytical analysis and finite element simulation of advanced membranes for silicon microphones , 2005, IEEE Sensors Journal.

[12]  Hannu Sipola,et al.  Capacitive microphone with low-stress polysilicon membrane and high-stress polysilicon backplate , 2000 .

[13]  Rongming Lin,et al.  Modeling and characterization of a silicon condenser microphone , 2004 .

[14]  Jaewoo Lee,et al.  A surface-micromachined MEMS acoustic sensor with X-shape bottom electrode anchor , 2009, 2009 IEEE Sensors.

[15]  Jaewoo Lee,et al.  A surface-micromachined MEMS acoustic sensor with back-plate anchors of 100 µm depth , 2011, 2011 IEEE SENSORS Proceedings.

[16]  Hong-Ching Her,et al.  Acoustic analysis and fabrication of microelectromechanical system capacitive microphones , 2008 .