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High temperature pressure sensor with low parasitic capacitance

  • US 4,701,826 A
  • Filed: 10/30/1986
  • Issued: 10/20/1987
  • Est. Priority Date: 10/30/1986
  • Status: Expired due to Fees
First Claim
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1. A silicon variable capacitance pressure sensor including:

  • a first lightly doped n (or p)-type silicon wafer having a first cavity with a first p+ (or n+) doped capacitor plate with a highly doped first p+ (or n+) semiconductor path through said first wafer contacting said first capacitance plate;

    a second lightly doped n (or p)-type silicon wafer having a second p+ doped (or r+) capacitor plate with a highly doped second p+ (or n+) semiconductor path through said second wafer contacting said second capacitor plate;

    an insulating layer attached to said first and second silicon wafers at a region outside the extent of said first cavity preventing electrically conductive coupling between said first and second wafers, thereby reducing parasitic capacitance between the first and semiconductor paths;

    said first and second capacitor plates being highly doped semiconductor regions positioned adjacent each other and separated from each other by the depth of said cavity;

    said insulating layer being formed of silicon dioxide thereby producing a structure suitable for operation at relatively high temperature; and

    said first and second silicon wafers being adapted for having formed therein an integrated circuit.

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