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 transducer cells disposed proximate a first side of the ultrasonic transducer substrate;
for at least one transducer cell, one or more conductive bond connections disposed between a second side of the ultrasonic transducer substrate and an electrical substrate; and
a single conductive bond connection connected to at least one acoustically inactive region of a plurality of acoustically inactive regions of the ultrasonic transducer substrate, each single conductive bond connection disposed between the ultrasonic transducer substrate and the electrical substrate.
2. The apparatus of claim 1 , wherein the one or more 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 the one or more conductive bond connections comprise one or more of: thermal compression connections, eutectic connections and silicide connections.
4. The apparatus of claim 1 , wherein the one or more 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 electrical 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 one or more bond connections is separated from a nearest neighbor bond connection by a distance of about 100 microns (μm) or less.
10. The apparatus of claim 1 , wherein the ultrasonic transducer substrate and the electrical substrate are bonded together to define a plurality of cavities between them.
11. The apparatus of claim 10 , wherein each of the plurality of transducer cells corresponds to a cavity of the plurality of cavities.
12. The apparatus of claim 1 , further comprising a seal ring surrounding an ultrasonic transducer array defined by the plurality of transducer cells.
13. The apparatus of claim 12 , wherein the seal ring provides an electrical connection between the ultrasonic transducer substrate and the electrical substrate.
14. The apparatus of claim 1 , further comprising a probe, wherein the ultrasound-on-a-chip device is disposed within the probe.