Patent ID: 6906529

Claim:
A sensor device comprising: a substrate; a composite interconnect structure disposed on the substrate, the structure including layers of conductive and insulating material, the structure having an upper layer of insulating material that defines a sensing surface; circuit elements having regions within the substrate; conductive interconnects in the composite interconnect structure for interconnecting the circuit elements; and an array of pixels for sensing an object finger, in close proximity to the sensing surface; wherein each pixel includes a subarray of upper capacitor plates embedded in insulating material of the composite interconnect structure at a level just beneath the sensing surface, first and second lower capacitor plates disposed at a level beneath the upper capacitor plates, a memory cell corresponding to each upper capacitor plate for selectively connecting its respective upper capacitor plate to either the first or the second lower capacitor plate, and a sensor circuit connected to the first and second lower capacitor plates for generating an output signal at a predetermined time in a controlled sequence of events, whereby the output signal is a function of the capacitance sensed at the portion of the sensing surface corresponding to the pixel.