Boundary acoustic wave device
Aspects of this disclosure relate to an acoustic wave device that includes high velocity layers on opposing sides of a piezoelectric layer. A temperature compensation layer can be positioned between one of the high velocity layers and the piezoelectric layer. The acoustic wave device can be arranged to generate a boundary acoustic wave having a higher velocity than a respective acoustic velocity of each of the high velocity layers.
1. An acoustic wave device comprising:
a piezoelectric layer;
an interdigital transducer electrode on the piezoelectric layer;
high velocity layers on opposing side of the piezoelectric layer, the high velocity layers including a first high velocity layer having a first acoustic velocity and a second high velocity layer having a second acoustic velocity;
a temperature compensation layer in physical contact with the interdigital transducer electrode and positioned between the first high velocity layer and the piezoelectric layer; and
an adhesion layer within the temperature compensation layer such that the adhesion layer is positioned between a first portion of the temperature compensation layer and a second portion of the compensation layer, the adhesion layer arranged to enhance power durability of the acoustic wave device, the acoustic wave device being configured to generate a boundary acoustic wave such that acoustic energy is concentrated at an interface of the piezoelectric layer and the temperature compensation layer, the boundary acoustic wave having a velocity that is less than both the first acoustic velocity and the second acoustic velocity, the boundary acoustic wave having a wavelength of λ, and the thickness of the second high velocity layer being at least 10λ.
2. The acoustic wave device of claim 1 wherein the first acoustic velocity is substantially the same as the second acoustic velocity.
3. The acoustic wave device of claim 1 wherein the first acoustic velocity is different than the second acoustic velocity.
4. The acoustic wave device of claim 1 wherein the first high velocity layer is a silicon layer.
5. The acoustic wave device of claim 4 wherein the second high velocity layer is a second silicon layer.
6. The acoustic wave device of claim 1 wherein the first high velocity layer includes at least one of silicon nitride, aluminum nitride, diamond, quartz, or spinel.
7. The acoustic wave device of claim 1 wherein the piezoelectric layer is either a lithium tantalate layer or a lithium niobate layer.
8. The acoustic wave device of claim 1 further comprising a via extending through the acoustic wave device.
9. The acoustic wave device of claim 1 wherein the first high velocity layer has a thickness of at least 10λ.
10. The acoustic wave device of claim 1 further comprising a low velocity layer positioned between the piezoelectric layer and the second high velocity layer.
11. The acoustic wave device of claim 10 further comprising a second adhesion layer within the low velocity layer such that the second adhesion layer is positioned between a first portion of the low velocity layer and a second portion of the low velocity layer.
12. The acoustic wave device of claim 1 wherein the piezoelectric layer has a thickness of less than 2λ.
13. An acoustic wave device comprising:
a piezoelectric layer;
an interdigital transducer electrode on the piezoelectric layer;
silicon layers on opposing sides of the piezoelectric layer, the silicon layers including a first silicon layer and a second silicon layer; and
a silicon dioxide layer disposed between the first silicon layer and the piezoelectric layer, the acoustic wave device being configured to generate a boundary acoustic wave such that maximum displacement in an acoustic displacement distribution is centered at an interface of the piezoelectric layer and the silicon dioxide layer, the boundary acoustic wave having a wavelength of λ, the second silicon layer having a thickness sufficient to maintain mechanical durability of the acoustic wave device, the thickness of the second silicon layer being at least 10λ, and the acoustic wave device having a thickness in a range from 10 micrometers to 100 micrometers.
14. The acoustic wave device of claim 13 wherein the thickness of the second silicon layer is less than 100λ.
15. The acoustic wave device of claim 13 wherein the piezoelectric layer has a thickness of no greater than 2λ.
16. The acoustic wave device of claim 13 wherein the piezoelectric layer is a lithium tantalate layer.
17. The acoustic wave device of claim 13 wherein the piezoelectric layer is a lithium niobate layer.
18. The acoustic wave device of claim 13 further comprising a second silicon dioxide layer and an adhesion layer within the second silicon dioxide layer, the second silicon dioxide layer positioned on a side of the piezoelectric layer opposite to the silicon dioxide layer.
19. The acoustic wave device of claim 13 further comprising an adhesion layer within the silicon dioxide layer positioned between a first portion of the silicon dioxide layer and a second portion of the silicon dioxide layer.
20. An acoustic wave filter comprising an acoustic wave device that includes a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, silicon layers on opposing sides of the piezoelectric layer, a silicon dioxide layer disposed between one of the silicon layers and the piezoelectric layer, and an adhesion layer within the silicon dioxide layer, the acoustic wave device being configured to generate a boundary acoustic wave such that acoustic energy is concentrated at an interface of the piezoelectric layer and the silicon dioxide layer, at least one of the silicon layers having a thickness sufficient to maintain mechanical durability of the acoustic wave device, and the acoustic wave filter configured to filter a radio frequency signal.