Electrode-defined unsuspended acoustic resonator

1. A bulk acoustic resonator comprising:

a resonator body including:

a piezoelectric layer, wherein the piezoelectric layer is a single crystal of LiNbO 3 cut at an angle and having a thickness, the angle and the thickness being conducive to a Mode3 resonance or a Mode 4 resonance with a predetermined coupling efficiency;

a device layer located below the piezoelectric layer; and

a top conductive layer located above the piezoelectric layer opposite the device layer,

wherein substantially all of a surface of the device layer opposite the piezoelectric layer is for mounting the resonator body to a carrier that is not part of the resonator body.

2. The bulk acoustic resonator of claim 1 , wherein the single crystal of LiNbO 3 is cut at the angle of 130°±30°; 130°±20°; 130°±10°; 0°±30°; or 0°±20°.

3. The bulk acoustic resonator of claim 1 , wherein the single crystal of LiNbO 3 is cut at the angle of 0°±10°; and wherein the Mode3 or the Mode 4 resonance is at a frequency ≥0.1 GHz.

4. The bulk acoustic resonator of claim 1 , comprising at least one of the following:

the Mode3 resonance having the predetermined coupling efficiency ≥8%; and

the Mode4 resonance having the predetermined coupling efficiency ≥3%.

5. The bulk acoustic resonator of claim 4 , wherein, for the Mode4 resonance, the single crystal of LiNbO 3 has the thickness ≤0.5λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on the thickness of the single crystal of LiNbO 3 .

6. The bulk acoustic resonator of claim 4 , wherein, for the Mode3 resonance, the single crystal of LiNbO 3 has the thickness ≤2λ, wherein a value of λ is based on a dimension of a pattern or feature defined by top conductive layer or based on the thickness of the single crystal of LiNbO 3 .

7. The bulk acoustic resonator of claim 1 , further including, located between the piezoelectric layer and the device layer, a bottom conductive layer having a thickness ≥0.010λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on the thickness of the single crystal of LiNbO 3 .

8. The bulk acoustic resonator of claim 1 , wherein the device layer has a thickness ≥50 nm.

9. The bulk acoustic resonator of claim 1 , further including, located between the piezoelectric layer and the device layer, a layer of low acoustic impedance material having an acoustic impedance between 10 6 Pa-s/m 3 and 30×10 6 Pa-s/m 3 and a thickness ≥0.05λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on the thickness of the single crystal of LiNbO 3 .

10. The bulk acoustic resonator of claim 1 , further including, located between the piezoelectric layer and the device layer, a layer of high acoustic impedance material having an acoustic impedance between 10 6 Pa-s/m 3 and 630×106 Pa-s/m 3 and a thickness ≥0.05λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on the thickness of the single crystal of LiNbO 3 .

11. The bulk acoustic resonator of claim 1 , further including, located between the piezoelectric layer and the device layer, a temperature compensation layer comprising Si and oxygen having a thickness ≤2λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on the thickness of the single crystal of LiNbO 3 .

12. The bulk acoustic resonator of claim 1 , further including a passivation layer.

13. The bulk acoustic resonator of claim 1 , wherein the top conductive layer includes at least one pair of spaced conductive fingers.

14. The bulk acoustic resonator of claim 1 , further including, located between the piezoelectric layer and the device layer, plural alternating temperature compensation layers and high acoustic impedance layers.

15. The bulk acoustic resonator of claim 1 , wherein the device layer comprises at least one of the following: diamond; W; SiC; Ir, AlN, Al; Pt; Pd; Mo; Cr; Ti; Ta; an element from Group 3A or 4A of the periodic table of the elements; a transition element from Group 1B, 2B, 3B, 4B, 5B, 6B, 7B, or 8B of the periodic table of the elements; ceramic; glass; and polymer.

16. A bulk acoustic resonator comprising:

a resonator body including:

a piezoelectric layer, wherein the piezoelectric layer is a single crystal of LiNbO 3 ;

a device layer;

a top conductive layer on the piezoelectric layer opposite the device layer, wherein substantially all of a surface of the device layer opposite the piezoelectric layer is for mounting the resonator body to a carrier that is not part of the resonator body; and

plural alternating temperature compensation layers and high acoustic impedance layers located between the piezoelectric layer and the device layer.

17. The bulk acoustic resonator of claim 16 , wherein the single crystal of LiNbO 3 is cut at an angle of 130°±30°; 130°±20°; 130°±10°; 0°±30°; or 0°±20°.

18. The bulk acoustic resonator of claim 16 , wherein the single crystal of LiNbO 3 is cut at an angle of 0°±10°; and wherein a Mode3 or a Mode 4 resonance is at a frequency ≥0.1 GHz.

19. The bulk acoustic resonator of claim 16 , comprising at least one of the following:

a Mode3 resonance having a predetermined coupling efficiency ≥8%; and

a Mode4 resonance having a predetermined coupling efficiency ≥3%.

20. The bulk acoustic resonator of claim 19 ,

wherein, for the Mode4 resonance, the single crystal of LiNbO 3 has a thickness ≤0.5λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on the thickness of the single crystal of LiNbO 3 ; or

wherein, for the Mode3 resonance, the single crystal of LiNbO 3 has a thickness ≤2λ, wherein a value of λ is based on a dimension of a pattern or feature defined by top conductive layer or based on the thickness of the single crystal of LiNbO 3 .

21. The bulk acoustic resonator of claim 16 , further including:

a bottom conductive layer located between the piezoelectric layer and the device layer, the bottom conductive layer having a thickness ≥0.010λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on a thickness of the single crystal of LiNbO 3 ; and/or

a layer of low acoustic impedance material, located between the piezoelectric layer and the device layer, the low acoustic impedance material having an acoustic impedance between 10 6 Pa-s/m 3 and 30×10 6 Pa-s/m 3 and a thickness ≥0.05λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on a thickness of the single crystal of LiNbO 3 .

22. The bulk acoustic resonator of claim 16 , wherein one of the plural alternating temperature compensation layers and high acoustic impedance layers comprises:

a layer of high acoustic impedance material located between the piezoelectric layer and the device layer, the high acoustic impedance material having an acoustic impedance between 10 6 Pa-s/m 3 and 630×106 Pa-s/m 3 and a thickness ≥0.05λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on a thickness of the single crystal of LiNbO 3 ; and/or

a layer of temperature compensation material located between the piezoelectric layer and the device layer, the temperature compensation material comprising Si and oxygen and having a thickness ≤2λ, wherein a value of λ is based on a dimension of a pattern or feature defined by the top conductive layer or based on a thickness of the single crystal of LiNbO 3 .

23. The bulk acoustic resonator of claim 16 ,

wherein the top conductive layer includes at least one pair of spaced conductive fingers;

wherein the device layer has a thickness ≥50 nm; and/or

wherein the device layer comprises at least one of the following: diamond; W;

SiC; Ir, AlN, Al; Pt; Pd; Mo; Cr; Ti; Ta; an element from Group 3A or 4A of the periodic table of the elements; a transition element from Group 1B, 2B, 3B, 4B, 5B, 6B, 7B, or 8B of the periodic table of the elements; ceramic; glass; and polymer.