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High-sensitivity z-axis vibration sensor and method of fabricating the same

  • US 8,263,426 B2
  • Filed: 07/24/2009
  • Issued: 09/11/2012
  • Est. Priority Date: 12/03/2008
  • Status: Expired due to Fees
First Claim
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1. A method of fabricating a high-sensitivity MEMS-type z-axis vibration sensor, comprising:

  • providing a silicon on insulator (SOI) substrate comprising an upper silicon layer disposed over a thermal oxide layer, and a silicon wafer disposed under the thermal oxide layer;

    doping the upper silicon layer with impurities to form a lower electrode;

    forming a silicon dummy ring in the doped upper silicon layer to define a center mass region of the doped upper silicon layer;

    forming a second upper oxide layer to a predetermined thickness and a polysilicon layer over the doped upper silicon layer;

    doping the polysilicon layer with impurities to form a center ground electrode;

    forming a sacrificial oxide layer and an upper electrode over the doped polysilicon layer;

    etching a lower surface of the silicon wafer to isolate the center mass region of the doped upper silicon layer; and

    etching the sacrificial oxide layer and the second upper oxide layer through an upper surface of the upper electrode, and forming a vibration space in which the doped polysilicon layer is capable of vibrating in a z-axis direction.

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