BULK ACOUSTIC WAVE (BAW) RESONATOR STRUCTURES, DEVICES AND SYSTEMS

Abstract

Techniques for improving Bulk Acoustic Wave (BAW) resonator structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. A top acoustic reflector including a first pair of top metal electrode layers may be electrically and acoustically coupled with the first layer of piezoelectric material to excite the piezoelectrically excitable main resonance mode at a resonant frequency.

Description

Claims

1. A bulk acoustic wave resonator comprising: a substrate;a stack including at least first, second and third piezoelectric layers, in which the first piezoelectric layer has a first piezoelectric axis orientation, and the second piezoelectric layer has a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first piezoelectric layer, and in which the first, second and third piezoelectric layers have respective thicknesses to facilitate the bulk acoustic wave resonator having a main resonant frequency substantially higher than ten GigaHertz; anda top multilayer acoustic reflector electrode including at least a triplet of top metal electrode layers electrically and acoustically coupled with the first, second and third piezoelectric layers to excite the main resonant frequency.

2. The bulk acoustic wave resonator as in claim 1 comprising a bottom multilayer acoustic reflector electrode.

3. The bulk acoustic wave resonator as in claim 2 in which a first mesa structure of the bulk acoustic wave resonator comprises the first, second and third piezoelectric layers, a second mesa structure of the bulk acoustic wave resonator comprises the bottom multilayer acoustic reflector electrode, and a third mesa structure of the bulk acoustic wave resonator comprises the top multilayer acoustic reflector electrode.

4. The bulk acoustic wave resonator as in claim 2 in which the bottom multilayer acoustic reflector electrode includes at least a triplet of bottom metal electrode layers electrically and acoustically coupled with the first, second and third piezoelectric layers to excite the main resonant frequency.

5. The bulk acoustic wave resonator as in claim 1 comprising an etched edge region extending through the first, second and third piezoelectric layers.

6. The bulk acoustic wave resonator as in claim 1 in which: the top multilayer acoustic reflector electrode includes at least a second triplet of top metal electrode layers electrically and acoustically coupled with the third piezoelectric layer to excite the main resonant frequency; andmembers of the triplet of top metal electrode layers and the second triplet of top metal electrode layers have respective acoustic impedances in an alternating arrangement.

7. The bulk acoustic wave resonator as in claim 1 comprising fourth and fifth piezoelectric layers arranged over the first, second and third piezoelectric layers.

8. The bulk acoustic wave resonator as in claim 1 in which the top multilayer acoustic reflector electrode has thermal resistance of three thousand degrees Kelvin per Watt or less at the main resonant frequency of the bulk acoustic wave resonator.

9. The bulk acoustic wave resonator as in claim 1 in which the bulk acoustic wave resonator has a quality factor of approximately 730 or greater.

10. The bulk acoustic wave resonator as in claim 1 in which the top multilayer acoustic reflector electrode has sheet resistance of less than one Ohm per square at the main resonant frequency of the bulk acoustic wave resonator.

11. The bulk acoustic wave resonator as in claim 1 in which the main resonant frequency of the bulk acoustic wave resonator is in a Ka band, as associated with an Institute of Electrical and Electronic Engineers (IEEE).

12. The bulk acoustic wave resonator as in claim 1 in which the main resonant frequency of the bulk acoustic wave resonator is in a 3rd Generation Partnership Project (3GPP) band.

13. The bulk acoustic wave resonator as in claim 1 in which the main resonant frequency of the bulk acoustic wave resonator is in at least one of a 3GPP n257 band, a 3GPP n258 band, a 3GPP n260 band, and a 3GPP n261 band.

14. The bulk acoustic wave resonator as in claim 1 in which a peak acoustic reflectivity of the top multilayer acoustic reflector electrode is in one of a Ku band, a K band, a Ka band, a V band, and a W band.

15. The bulk acoustic wave resonator as in claim 1 in which the main resonant frequency of the bulk acoustic wave resonator is in a 3GPP n258 band.

16. The bulk acoustic wave resonator as in claim 1 comprising: a via extending into the substrate; anda bottom electrode, in which the bottom electrode is at least partially disposed in the via.

17. An acoustic wave device, comprising: a top multilayer metal acoustic wave reflector;a bottom multilayer metal acoustic wave reflector; anda stack between the top multilayer metal acoustic wave reflector and the bottom multilayer metal acoustic wave reflector, the stack including at least first, second, third and fourth piezoelectric layers having respective thicknesses to facilitate a main acoustic resonance frequency of substantially greater than ten Gigahertz, in which: the top multilayer metal acoustic wave reflector includes at least a triplet of top metal layers electrically interfacing with the fourth piezoelectric layer;the bottom multilayer metal acoustic wave reflector at least a plurality of bottom metal layers electrically interfacing with the first piezoelectric layer; and the stack of piezoelectric layers is free of any interposing electrode.

18. The acoustic wave device of claim 17 in which the acoustic wave device has a quality factor of approximately 730 or greater.

19. A resonator ladder filter comprising a plurality of acoustic wave resonator devices electrically coupled to facilitate the resonator ladder filter, in which the plurality of acoustic wave resonator devices includes at least a first acoustic wave resonator device, the first acoustic wave resonator device including at least: a top multilayer metal acoustic wave reflector;a bottom multilayer metal acoustic wave reflector; anda stack between the top multilayer metal acoustic wave reflector and the bottom multilayer metal acoustic wave reflector including at least first, second, third and fourth piezoelectric layers having respective thicknesses to facilitate a main acoustic resonance frequency substantially greater than ten GigaHertz, in which: the top multilayer metal acoustic wave reflector includes at least a triplet of top metal layers electrically interfacing with the fourth piezoelectric layer;the bottom multilayer metal acoustic wave reflector includes at least a plurality of metal layers electrically interfacing with the first piezoelectric layer; andthe stack of piezoelectric layers is free of any interposing electrode.

20. The resonator ladder filter of claim 19 in which the main acoustic resonance frequency of the first acoustic wave device is in the K band, as associated with an Institute of Electrical and Electronic Engineers (IEEE).

21. The resonator ladder filter of claim 19 in which the main acoustic resonance frequency of the first acoustic wave device is in at least one of a 3GPP n257 band, a 3GPP n258 band, a 3GPP n260 band, and a 3GPP n261 band.

22. A bulk acoustic wave resonator comprising: a substrate;a first piezoelectric layer having a first piezoelectric axis orientation;a second piezoelectric layer acoustically coupled to the first piezoelectric layer, the second piezoelectric layer having a second piezoelectric axis orientation that is antiparallel to the first piezoelectric axis orientation;third and fourth piezoelectric layers; anda first multilayer metal acoustic wave reflector including at least a first triplet of metal layers electrically interfacing with the fourth piezoelectric layer to facilitate exciting a main resonant frequency in one of a Ku band, a K band, a Ka band, a V band, and a W band.

23. The bulk acoustic wave resonator of claim 22 comprising fifth and sixth piezoelectric layers.

24. The bulk acoustic wave resonator of claim 22 comprising a second multilayer metal acoustic wave reflector electrically interfacing with the first piezoelectric layer, the second multilayer metal acoustic wave reflector including at least a second triplet of metal layers.

25. A ladder filter comprising: a plurality of bulk acoustic wave resonators, the plurality of bulk acoustic wave resonators being electrically coupled to facilitate the ladder filter, the plurality of bulk acoustic wave resonators including at least a first bulk acoustic wave resonator, the first bulk acoustic wave resonator including at least:a top multilayer acoustic reflector electrode;a bottom multilayer acoustic reflector electrode; anda stack including at least a triplet of piezoelectric layers between the top multilayer acoustic reflector electrode and the bottom multilayer acoustic reflector electrode, in which the top multilayer acoustic reflector electrode includes at least a triplet of top metal electrode layers electrically and acoustically coupled with the triplet of piezoelectric layers to facilitate exciting a main resonant frequency associated with the stack of piezoelectric layers, and in which the main resonant frequency associated with the stack of piezoelectric layers is in one of a Ku band, a K band, a Ka band, a V band, and a W band, as associated with an Institute of Electrical and Electronic Engineers (IEEE).

26. The ladder filter as in claim 25 in which the bottom multilayer acoustic reflector electrode includes at least a triplet of bottom metal electrode layers electrically and acoustically coupled with the triplet of piezoelectric layers to facilitate exciting the main resonant frequency.

27. The ladder filter as in claim 26 in which the triplet of top metal electrode layers includes at least a middle electrode layer having a middle acoustic impedance between a pair of electrode layers having acoustic impedances that are substantially different than the middle acoustic impedance of the middle electrode layer.

28. The ladder filter as in claim 25 in which: the triplet of piezoelectric layers includes at least a first piezoelectric layer having a first piezoelectric axis orientation; and the first bulk acoustic wave resonator includes at least a fourth piezoelectric layer having a fourth piezoelectric axis orientation that is antiparallel to the first piezoelectric orientation of the first piezoelectric layer.

29. An oscillator comprising: gain circuitry; anda bulk acoustic wave resonator including at least:a top multilayer acoustic reflector electrode; anda stack including at least first, second, third, and fourth piezoelectric layers, in which the first piezoelectric layer has a first piezoelectric axis orientation, and the second piezoelectric layer has a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first piezoelectric layer, in which the top multilayer acoustic reflector electrode includes at least a triplet of top metal electrode layers electrically coupled with the first, second, third and fourth piezoelectric layers and with the gain circuitry to facilitate exciting a main resonant frequency in one of a Ku band, a K band, a Ka band, a V band, and a W band, as associated with an Institute of Electrical and Electronic Engineers (IEEE).

30. The oscillator as in claim 29 in which: the gain circuitry includes at least a transistor; andthe bulk acoustic wave resonator includes at least a bottom multilayer acoustic reflector electrode, the bottom multilayer acoustic reflector electrode including at least a triplet of bottom metal electrode layers electrically and acoustically coupled with the first, second, third, and fourth piezoelectric layers.