Bulk acoustic wave resonator
View Patent ↗A bulk acoustic wave resonator includes a resonator region having electrodes and a piezoelectric layer among the electrodes. The piezoelectric layer has a groove that bounds at least part of an electroacoustically active region of the piezoelectric layer. A depth of the groove is at least 50% of a thickness of the piezoelectric layer.
1. A bulk acoustic wave resonator comprising:
a resonator region comprising electrodes and a piezoelectric layer among the electrodes;
wherein the piezoelectric layer has a groove that bounds at least part of an electroacoustically active region of the piezoelectric layer; and
wherein a depth of the groove is at least 50% of a thickness of the piezoelectric layer.
2. The bulk acoustic wave resonator of claim 1 , further comprising:
an acoustic mirror connected to the resonator region, the acoustic mirror comprising at least two layers, each of the at least two layers having a different acoustic impedance.
3. The bulk acoustic wave resonator of claim 2 , wherein a depth of the groove corresponds to a thickness of the piezoelectric layer.
4. The bulk acoustic wave resonator of claim 2 , wherein the acoustic mirror comprises an uppermost layer relative to a carrier substrate below the acoustic mirror; and
wherein the groove cuts into at least the uppermost mirror layer.
5. The bulk acoustic wave resonator of claim 1 , wherein the groove comprises an etched groove.
6. The bulk acoustic wave resonator of claim 1 , wherein the groove has a substantially V-shaped cross section.
7. The bulk acoustic wave resonator of claim 1 , wherein the piezoelectric layer comprises AlN.
8. The bulk acoustic wave resonator of claim 1 , further comprising:
an elastic material inside the groove.
9. The bulk acoustic wave resonator of claim 1 , wherein an angle of tilt of a piezoelectric axis within a region of the piezoelectric layer at least partially bounded by the groove does not exceed 2°.
10. The bulk acoustic wave resonator of claim 2 , wherein the groove comprises an etched groove.
11. The bulk acoustic wave resonator of claim 2 , wherein the groove has a substantially V-shaped cross section.
12. The bulk acoustic wave resonator of claim 2 , wherein the piezoelectric layer comprises AlN.
13. The bulk acoustic wave resonator of claim 2 , further comprising:
an elastic material inside the groove.
14. The bulk acoustic wave resonator of claim 2 , wherein an angle of tilt of a piezoelectric axis within a region of the piezoelectric layer at least partially bounded by the groove does not exceed 2°.
15. The bulk acoustic wave resonator of claim 1 , wherein the groove comprises a plurality of channels with intermittent interruptions that are disposed around the electroacoustically active region.
16. The bulk acoustic wave resonator of claim 1 , wherein the groove separates the electroacoustically active region of the piezoelectric layer from an outer region of the piezoelectric layer, the electroacoustically active region having a piezoelectric axis that is substantially vertically oriented and the outer region having a piezoelectric axis is tilted.