Pressure type fingerprint sensor fabrication method
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United States of America Patent
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-
Jul 6, 2004
Grant Date -
Nov 20, 2003
app pub date -
May 13, 2003
filing date -
May 17, 2002
priority date (Note) -
Expired
status (Latency Note)
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Abstract
The present invention provides a fabrication method of a pressure type fingerprint sensor, which uses the commercial integrated circuit process to form the sensor and the processing circuit together on the same chip. The present invention comprises a plurality of capacitive pressure sensors arranged in a 2-D array and applies the charge sharing principle to each capacitive pressure sensor for signal reading. The main structure of each pressure sensor is a pair of plate electrodes with an air gap between them to form a plate sensor capacitor, wherein the plate electrodes comprise a floating electrode and a fixed electrode. When the finger ridge contacts the floating electrode, the pressure from the finger changes the spacing of the air gap so as to change the capacitance of the plate sensor capacitor. The 2-D sensor array can read the 2-D pressure distribution pressed by the finger ridge to construct the fingerprint pattern.
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