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MEDIA-COMPATIBLE ELECTRICALLY ISOLATED PRESSURE SENSOR FOR HIGH TEMPERATURE APPLICATIONS

  • US 20100224004A1
  • Filed: 03/03/2009
  • Published: 09/09/2010
  • Est. Priority Date: 03/03/2009
  • Status: Active Grant
First Claim
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1. A Micro-Electro-Mechanical System (MEMS) pressure sensor, comprising:

  • a gauge wafer, comprising;

    a micromachined structure comprising a diaphragm region and a pedestal region, wherein a first surface of the diaphragm region is configured to be accessed by a pressurized medium that exerts a pressure resulting in a deflection of the diaphragm region;

    an electrical insulation layer disposed on a second surface of the diaphragm region opposite to the first surface; and

    a plurality of sensing elements patterned on the electrical insulation layer disposed on the second surface of the diaphragm region, wherein a thermal expansion coefficient of the material of the sensing elements substantially matches with a thermal expansion coefficient of the material of the gauge wafer;

    a cap wafer coupled to the gauge wafer, comprising;

    a recess on an inner surface of the cap wafer facing the gauge wafer that defines a sealed reference cavity that encloses the sensing elements and prevents exposure of the sensing elements to external environment;

    a plurality of through-wafer embedded vias made of an electrically conductive material to bring out electrical connections from the sensing elements to an outer surface of the cap wafer opposite to the inner recessed surface; and

    a spacer wafer with a central aperture aligned to the diaphragm region, bonded to the pedestal region of the micromachined structure.

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