Acoustic wave device with high thermal conductivity layer on interdigital transducer
An acoustic wave device includes a piezoelectric substrate, interdigital transducer electrodes including a predetermined number of electrode fingers disposed on an upper surface of the substrate, and a dielectric material layer having a first portion and a second portion. The first portion is disposed on the upper surface of the substrate and between the interdigital transducer electrode fingers. The second portion is disposed above the interdigital transducer electrode fingers. The acoustic wave device further includes at least one thermally conductive bridge disposed within the dielectric material layer and contacting upper surfaces of at least two adjacent interdigital transducer electrode fingers to dissipate heat therefrom.
1. An acoustic wave device comprising:
a piezoelectric substrate;
interdigital transducer electrodes including electrode fingers disposed on an upper surface of the substrate;
a dielectric material layer disposed on the upper surface of the substrate and between the interdigital transducer electrode fingers; and
a thermally conductive bridge disposed within the dielectric material layer and contacting upper surfaces of at least two adjacent interdigital transducer electrode fingers to dissipate heat therefrom.
2. The acoustic wave device of claim 1 wherein the thermally conductive bridge includes cap layers disposed on the upper surfaces of the at least two adjacent interdigital transducer electrode fingers.
3. The acoustic wave device of claim 2 wherein the cap layers include a material having a higher thermal conductivity than the dielectric material.
4. The acoustic wave device of claim 2 wherein a first portion of the dielectric material disposed on the upper surface of the substrate and between the interdigital transducer electrode fingers has a different composition than a second portion of the dielectric material disposed above the interdigital transducer electrode fingers.
5. The acoustic wave device of claim 2 wherein the cap layers have same widths as respective ones of the interdigital transducer electrode fingers upon which they are disposed, the widths being measured in a direction parallel to a direction of propagation of a main acoustic wave through the acoustic wave device.
6. The acoustic wave device of claim 2 wherein the cap layers are thinner than the interdigital transducer electrodes and thinner than the dielectric material layer.
7. The acoustic wave device of claim 6 wherein the cap layers are between 10 nm and 50 nm thick.
8. The acoustic wave device of claim 2 wherein the thermally conductive bridge further includes a heat dissipating layer disposed on and extending between the cap layers.
9. The acoustic wave device of claim 8 wherein the heat dissipating layer includes a material having a higher thermal conductivity than the dielectric material.
10. The acoustic wave device of claim 8 wherein the heat dissipating layer is formed of a different material than the cap layers.
11. The acoustic wave device of claim 8 wherein the heat dissipating layer is formed of a same material as the cap layers.
12. The acoustic wave device of claim 8 wherein the heat dissipating layer has an electrical resistance sufficiently high to prevent short circuits between adjacent interdigital transducer electrodes though the heat dissipating layer.
13. The acoustic wave device of claim 12 wherein the heat dissipating layer is formed of a ceramic material.
14. The acoustic wave device of claim 13 wherein the heat dissipating layer is formed of one of silicon nitride, aluminum nitride, aluminum oxide, spinel, or diamond.
15. The acoustic wave device of claim 8 wherein the heat dissipating layer is thinner than the interdigital transducer electrodes and thinner than the dielectric material layer.
16. The acoustic wave device of claim 15 wherein the heat dissipating layer is between 10 nm and 200 nm thick.
17. The acoustic wave device of claim 8 wherein the heat dissipating layer is disposed between a first portion of the dielectric material and a second portion of the dielectric material, the first portion of the dielectric material being disposed on the upper surface of the substrate and between the interdigital transducer electrode fingers, the second portion of the dielectric material being disposed above the interdigital transducer electrode fingers.
18. The acoustic wave device of claim 1 wherein the thermally conductive bridge covers an area in which the interdigital transducer electrodes are interleaved.
19. The acoustic wave device of claim 18 wherein the thermally conductive bridge further covers portions of bus bar electrodes from which the interdigital transducer electrodes extend.
20. The acoustic wave device of claim 18 wherein the thermally conductive bridge further covers reflector electrodes disposed on opposite sides of the interdigital transducer electrodes.
21. The acoustic wave device of claim 1 wherein the thermally conductive bridge includes a plurality of separate heat dissipating layers covering different respective portions of the interdigital transducer electrodes.
22. A radio frequency filter including the acoustic wave device of claim 1 .
23. An electronics module including the radio frequency filter of claim 22 .
24. An electronic device including the electronics module of claim 23 .