Acoustic wave devices with thermal bypass
An acoustic wave device can have a plurality of coupling portions configured to electrically couple electrodes of the device to the substrate of the device to provide a bypass current pathway through the substrate for heat management. The substrate can be a semiconductor material, which can become more conductive as the temperature increases so that the bypass current pathway diverts more power through the substrate as the temperature increases. The acoustic wave device can be a surface acoustic wave device, which can have an interdigital transducer electrode that has the coupling portions on each of the bus bars and extending through the piezoelectric layer to contact the substrate. The acoustic wave device can be a bulk acoustic wave device in some implementations.
1 . An acoustic wave device comprising:
a substrate that decreases in electrical resistivity in response to an increase in temperature;
a piezoelectric layer over the substrate; and
an interdigital transducer electrode over the piezoelectric layer, the interdigital transducer electrode including a first bus bar, a second bus bar and a plurality of fingers that transfer electrical current from the first bus bar to the second bus bar via a first pathway, the interdigital transducer electrode including a plurality of coupling portions with at least a first coupling portion coupled to the first bus bar and at least a second coupling portion connected to the second bus bar, the first and second coupling portions extend through at least part of the piezoelectric layer towards the substrate to electrically couple first and second bus bars with the substrate and transfer electrical current from the first bus bar to the second bus bar via a second pathway through the substrate to bypass the first pathway based at least in part on the temperature of the substrate.
2 . The device of claim 1 , wherein the substrate is made of a semiconductor material.
3 . The device of claim 1 , wherein the substrate is made of silicon.
4 . The device of claim 1 , wherein one or more of the plurality of coupling portions extend completely through the piezoelectric layer.
5 . The device of claim 1 , wherein one or more of the plurality of coupling portions are in direct contact with the substrate.
6 . The device of claim 1 , wherein one or more of the plurality of coupling portions are in ohmic contact with the substrate.
7 . The device of claim 1 , wherein one or more of the plurality of coupling portions are capacitively coupled to the substrate.
8 . The device of claim 7 , wherein a dielectric material is disposed between the one or more of the plurality of coupling portions and the substrate.
9 . The device of claim 1 , further comprising a dielectric layer between the piezoelectric layer and the substrate.
10 . The device of claim 9 , wherein one or more of the plurality of coupling portions extend at least partially through the dielectric layer.
11 . The device of claim 9 , wherein one or more of the plurality of coupling portions extend completely through the dielectric layer.
12 . The device of claim 1 , wherein the plurality of coupling portions are configured to provide a bypass current pathway through the substrate.
13 . The device of claim 1 , wherein the interdigital transducer electrode includes a first bus bar with a first coupling portion that electrically couples the first bus bar to the substrate and a second bus bar with a second coupling portion that electrical couples the second bus bar to the substrate.
14 . An acoustic wave device comprising:
a substrate that decreases in electrical resistivity in response to an increase in temperature;
a piezoelectric layer over the substrate; and
an interdigital transducer electrode, the piezoelectric layer disposed between the substrate and the interdigital transducer electrode, the interdigital transducer electrode including a first bus bar, second bus bar, a first plurality of fingers extending from the first bus bar toward the second bus bar, a second plurality of fingers extending towards the first bus bar, a first coupling portion on the first bus bar that extends through at least part of the piezoelectric layer towards the substrate to electrically couple the first bus bar to the substrate, and a second coupling portion on the second bus bar that extends through at least part of the piezoelectric layer towards the substrate to electrically couple the second bus bar to the substrate, the first and second coupling portions transfer electrical current from the first bus bar to the second bus bar through the substrate below the piezoelectric layer based at least in part on the temperature of the substrate.
15 . The device of claim 14 , wherein the substrate is made of a semiconductor material.
16 . The device of claim 14 , wherein the first and second coupling portions extend completely through the piezoelectric layer.
17 . The device of claim 14 , wherein the first and second coupling portions are in direct contact with the substrate.
18 . The device of claim 14 , wherein the first and second coupling portions are in ohmic contact with the substrate.
19 . The device of claim 14 , wherein the first and second coupling portions are capacitively coupled to the substrate.
20 . The device of claim 14 , further comprising a dielectric layer between the piezoelectric layer and the substrate.
21 . The device of claim 20 , wherein the first and second coupling portions extend at least partially through the dielectric layer.
22 . The device of claim 20 , wherein the first and second coupling portions extend completely through the dielectric layer.
23 . The device of claim 14 , wherein the first and second coupling portions are configured to provide a bypass current pathway through the substrate.
24 . The device of claim 14 , wherein the device is a surface acoustic wave device.
25 . The device of claim 14 , wherein the device is a multi-layer piezoelectric substrate device.
26 . A method of operating an acoustic wave device, the method comprising:
transferring electrical current from a first bus bar to a second bus bar via a first pathway through interdigitated fingers of an interdigital transducer electrode on a piezoelectric layer that is disposed between a substrate and the interdigital transducer electrode, the substrate decreasing in electrical resistivity in response to increasing temperature;
transferring electrical current from the first bus bar to the second bus bar via a second pathway through the substrate, the second pathway including a first coupling portion that extends from the first bus bar through the piezoelectric layer towards the substrate to electrically couple with the substrate, and the second pathway further including a second coupling portion that extends from the second bus bar through the piezoelectric layer towards the substrate to electrically couple with the substrate; and
bypassing the first pathway with the second pathway based at least in part on temperature of the substrate.