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Method for making an all-silicon capacitive pressure sensor

  • US 5,706,565 A
  • Filed: 09/03/1996
  • Issued: 01/13/1998
  • Est. Priority Date: 09/03/1996
  • Status: Expired due to Term
First Claim
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1. A method for forming a capacitive pressure sensor, the method comprising the steps of:

  • providing a first semiconductor wafer having at least a portion thereof characterized by a first electrical conductivity;

    forming a cavity in the first semiconductor wafer so as to expose a region of the semiconductor wafer that yields a fixed capacitor plate of the capacitive pressure sensor;

    bonding a semiconductor diaphragm of the first electrical conductivity type to the semiconductor wafer such that the diaphragm overlies the fixed capacitor plate, is electrically insulated from the fixed capacitor plates, and forms a hermetic seal around the fixed capacitor plate, the diaphragm being a flexible capacitor plate of the capacitive pressure sensor;

    wherein the flexible capacitor plate forms a gap with the fixed capacitor plate of up to about ten micrometers, such that a capacitive output signal of the capacitive pressure sensor is produced by changes in contact area between the diaphragm and the semiconductor wafer in response to pressure applied to the diaphragm.

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