Film bulk acoustic resonators in thin LN-LT layers
Acoustic resonator devices, filter devices, and methods of fabrication are disclosed. A resonator device includes a single-crystal piezoelectric plate having a front surface and a back surface opposite the front surface, wherein the back surface is coupled to a surface of a substrate. A floating back-side conductor pattern is formed on a portion of the back surface. A front-side conductor pattern including two electrodes is formed on a portion of the front surface opposite the back-side conductor.
1. An acoustic resonator device comprising:
a single-crystal piezoelectric plate having a front surface and a back surface opposite the front surface, wherein the back surface is coupled to a surface of a substrate;
a floating back-side conductor pattern formed on the back surface; and
a front-side conductor pattern comprising two electrodes formed on a portion of the front surface opposite the back-side conductor pattern, wherein the front-side conductor pattern comprises interleaved fingers connected to busbars of opposite polarity, and wherein the interleaved fingers have a non-rectangular shape.
2. The device of claim 1 , wherein a radio frequency signal applied between the two electrodes excites a primary acoustic mode in the single-crystal piezoelectric plate.
3. The device of claim 1 , wherein the back-side conductor pattern is an acoustic Bragg reflector.
4. The device of claim 3 , wherein the acoustic Bragg reflector is between the surface of the substrate and the back surface of the single-crystal piezoelectric plate.
5. The device of claim 1 , wherein a portion of the single-crystal piezoelectric plate between the two electrodes is recessed to form a slot.
6. A method of fabricating an acoustic resonator device comprising:
coupling a back surface of a single-crystal piezoelectric plate to a substrate, the single-crystal piezoelectric plate having a front surface opposite the back surface;
forming a floating back-side conductor pattern on the back surface; and
forming a front-side conductor pattern consisting of two electrodes on a portion of the front surface opposite the back-side conductor pattern, wherein the front-side conductor pattern comprises interleaved fingers connected to busbars of opposite polarity, and wherein the interleaved fingers have a non-rectangular shape.
7. The method of claim 6 , wherein a radio frequency signal applied between the two electrodes excites a primary acoustic mode in the single-crystal piezoelectric plate.
8. The method of claim 6 , wherein the back-side conductor pattern is an acoustic Bragg reflector.
9. The method of claim 8 , wherein the acoustic Bragg reflector is between the substrate and the back surface of the single-crystal piezoelectric plate.
10. The method of claim 6 , wherein a portion of the single-crystal piezoelectric plate between the two electrodes is removed to form a slot.
11. An acoustic resonator device comprising:
a single-crystal piezoelectric plate having a front surface and a back surface opposite the front surface, wherein the back surface is coupled to a surface of a substrate;
a floating back-side conductor pattern formed on the back surface; and
a front-side conductor pattern comprising two electrodes formed on a portion of the front surface opposite the back-side conductor pattern, wherein a portion of the single-crystal piezoelectric plate between the two electrodes is recessed to form a slot.
12. The device of claim 11 , wherein a radio frequency signal applied between the two electrodes excites a primary acoustic mode in the single-crystal piezoelectric plate.
13. The device of claim 11 , wherein the back-side conductor pattern is an acoustic Bragg reflector.
14. The device of claim 13 , wherein the acoustic Bragg reflector is between the surface of the substrate and the back surface of the single-crystal piezoelectric plate.
15. A method of fabricating an acoustic resonator device comprising:
coupling a back surface of a single-crystal piezoelectric plate to a substrate, the single-crystal piezoelectric plate having a front surface opposite the back surface;
forming a floating back-side conductor pattern on the back surface; and
forming a front-side conductor pattern consisting of two electrodes on a portion of the front surface opposite the back-side conductor pattern, wherein a portion of the single-crystal piezoelectric plate between the two electrodes is recessed to form a slot.
16. The method of claim 15 , wherein a radio frequency signal applied between the two electrodes excites a primary acoustic mode in the single-crystal piezoelectric plate.
17. The method of claim 15 , wherein the back-side conductor pattern is an acoustic Bragg reflector.
18. The method of claim 15 , wherein the acoustic Bragg reflector is between the substrate and the back surface of the single-crystal piezoelectric plate.