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Fingerprint sensors using membrane switch arrays

  • US 7,638,350 B2
  • Filed: 05/02/2005
  • Issued: 12/29/2009
  • Est. Priority Date: 05/16/2000
  • Status: Expired due to Fees
First Claim
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1. A method of making an integrated texture sensor for sensing a texture that is protected from external contaminating particulates and will self-equalize using air from outside the sensor, comprising:

  • a) forming a plurality of conductive row lines and a plurality of conductive column lines on a substrate, each of the row lines being insulated from each other and each of the column lines being insulated from each other, the row lines and column lines intersecting to form a switch area between adjacent row lines and adjacent column lines;

    b) forming a lower electrode in each of a plurality of switch areas;

    c) forming a sacrificial area directly over each lower electrode and a non-sacrificial area around each sacrificial area;

    d) forming an individual membrane above each sacrificial area, the individual membrane being anchored to the non-sacrificial area, the individual membrane comprising an upper electrode disposed directly above the sacrificial area, wherein the individual membrane does not cover a channel area adjacent to the sacrificial area and is separate from individual membranes formed above other sacrificial areas;

    e) removing each sacrificial area by introducing a sacrificial etchant through the channel area, thereby forming a cavity region at each sacrificial area; and

    f) sealing the channel area adjacent to each sacrificial area by forming a vent seal having a thickness selected to close each cavity region from the external contaminating particulates while permitting self-equalization of air pressure within the each cavity region with air that is external to the sensor.

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