Electrical contact arrangement for microfabricated ultrasonic transducer
An ultrasound-on-a-chip device has an ultrasonic transducer substrate with plurality of transducer cells, and an electrical substrate. For each transducer cell, one or more conductive bond connections are disposed between the ultrasonic transducer substrate and the electrical substrate. Examples of electrical substrates include CMOS chips, integrated circuits including analog circuits, interposers and printed circuit boards.
1 . An apparatus, comprising:
an ultrasound-on-a-chip device comprising an ultrasonic transducer substrate having a plurality of individual ultrasonic transducer cells disposed proximate a first side of the ultrasonic transducer substrate; and
for each individual transducer cell, multiple conductive bond connections disposed between a second side of the ultrasonic transducer substrate and an integrated circuit substrate, wherein the first side of the ultrasonic transducer substrate faces away from the integrated circuit substrate while the second side of the ultrasonic transducer substrate faces toward the integrated circuit substrate; and
a plurality of acoustically inactive regions of the ultrasonic transducer substrate each acoustically inactive region of the plurality of acoustically inactive regions including a single conductive bond connection connected to the integrated circuit substrate.
2 . The apparatus of claim 1 , wherein the multiple conductive bond connections are distributed substantially evenly with respect to an area of a transducer cell of the plurality of transducer cells.
3 . The apparatus of claim 1 , wherein multiple conductive bond connections comprise one or more of: thermal compression connections, eutectic connections and silicide connections.
4 . The apparatus of claim 1 , wherein the multiple conductive bond connections contact a conductive portion of a silicon layer of the ultrasonic transducer substrate at a first end thereof, and a metal layer of the integrated circuit substrate at a second end thereof.
5 . The apparatus of claim 1 , wherein the plurality of acoustically inactive regions of the ultrasonic transducer substrate are disposed between adjacent pairs of transducer cells of the plurality of transducer cells.
6 . The apparatus of claim 5 , wherein the plurality of transducer cells are electrically isolated from one another on a conductive portion of a silicon layer of the ultrasonic transducer substrate by isolation trenches formed in the silicon layer.
7 . The apparatus of claim 6 , wherein the isolation trenches form octagonal regions corresponding to individual transducer cells of the plurality of transducer cells.
8 . The apparatus of claim 7 , wherein the acoustically inactive regions are defined by a border between four adjacent octagonal regions.
9 . The apparatus of claim 1 , wherein each of the multiple bond connections is separated from a nearest neighbor bond connection by a distance of about 100 microns (μm) or less.