Transversely-excited film bulk acoustic resonator package and method
Acoustic resonator devices and filters are disclosed. An acoustic resonator chip includes a piezoelectric plate attached to a substrate, a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A first conductor pattern formed on a surface of the piezoelectric plate includes interleaved fingers of an interdigital transducer on the diaphragm and a first plurality of contact pads. A second conductor pattern is formed on a surface of an interposer, the second conductor pattern including a second plurality of contact pads. Each pad of the first plurality of contact pads is directly connected to a respective pad of the second plurality of contact pads. A seal is formed between a perimeter of the piezoelectric plate and a perimeter of the interposer.
1. An acoustic resonator device comprising:
an acoustic resonator chip comprising:
a substrate;
a piezoelectric plate supported by a front surface of the substrate, a portion of the piezoelectric plate forming a diaphragm spanning a cavity; and
a first conductor pattern at a surface of the piezoelectric plate, the first conductor pattern comprising an interdigitated transducer (IDT), interleaved fingers of the IDT on the diaphragm, and a first plurality of contact pads;
an interposer comprising a second conductor pattern, the second conductor pattern comprising a second plurality of contact pads on a back surface of the interposer; and
a seal connecting a perimeter of the piezoelectric plate to a perimeter of the interposer,
wherein each contact pad of the first plurality of contact pads is directly connected to a respective contact pad of the second plurality of contact pads.
2. The acoustic resonator device of claim 1 , wherein
the cavity is a hole passing through a thickness of the substrate, and
the acoustic resonator device further comprises a cap bonded to a back surface of the substrate.
3. The acoustic resonator device of claim 1 , wherein
the first conductor pattern further comprises a first conductor about the perimeter of the piezoelectric plate,
the second conductor pattern further comprises a second conductor about the perimeter of the interposer, and
the seal is the first conductor directly bonded to the second conductor.
4. The acoustic resonator device of claim 1 , wherein the seal comprises an adhesive material.
5. The acoustic resonator device of claim 1 , wherein the interposer further comprises vias connecting the second plurality of contact pads to a third plurality of contact pads formed on the front surface of the interposer.
6. The acoustic resonator device of claim 5 , wherein
the interposer comprises a silicon base; and
the vias are through silicon vias.
7. The acoustic resonator device of claim 5 , wherein the interposer is a low temperature co-fired ceramic circuit card.
8. The acoustic resonator device of claim 5 , wherein the interposer is a printed circuit board.
9. The acoustic resonator device of claim 1 , the interposer further comprising:
a recess facing the diaphragm.
10. The acoustic resonator device of claim 9 , wherein a distance from a bottom of the recess to the diaphragm is greater than or equal to 15 microns and less than or equal to 100 microns.
11. The acoustic resonator device of claim 1 , wherein
the acoustic resonator device is a bandpass filter;
a plurality of cavities in the substrate;
a plurality of portions of the piezoelectric plate form a corresponding plurality of diaphragms spanning respective cavities of the plurality of cavities; and
the first conductor pattern includes a plurality of IDTs, interleaved fingers of each IDT on a respective diaphragm of the plurality of diaphragms.
12. The acoustic resonator device of claim 1 , wherein the IDT and the piezoelectric plate are configured such that a radio frequency signal applied to the IDT excites a bulk shear acoustic wave in the diaphragm.
13. A filter device comprising:
an acoustic resonator chip comprising:
a substrate;
at least one piezoelectric plate supported by a front surface of the substrate, portions of the at least one piezoelectric plate forming a plurality of diaphragms spanning respective cavities;
a first conductor pattern at a surface of the at least one piezoelectric plate, the first conductor pattern including:
a plurality of interdigitated transducers (IDTs) of a corresponding plurality of acoustic resonators, interleaved fingers of each of the IDTs on a respective diaphragm from the plurality of diaphragms, and
a first plurality of contact pads;
an interposer comprising a second conductor pattern, the second conductor pattern comprising a second plurality of contact pads on a back surface of the interposer; and
a seal connecting a perimeter of the at least one piezoelectric plate to a perimeter of the interposer,
wherein each contact pad of the first plurality of contact pads is directly connected to a respective contact pad of the second plurality of contact pads.
14. The filter device of claim 13 , wherein
the cavities are holes passing through a thickness of the substrate,
the filter device further comprising a cover bonded to a back surface of the substrate.
15. The filter device of claim 13 , wherein
the first conductor pattern further comprises a first conductor about the perimeter of the at least one piezoelectric plate,
the second conductor pattern further comprises a second conductor about the perimeter of the interposer, and
the seal is the first conductor directly bonded to the second conductor.
16. The filter device of claim 13 , wherein the seal comprises an adhesive material.
17. The filter device of claim 13 , wherein the interposer further comprises:
conductive vias to connect the second plurality of contact pads to a third plurality of contact pads on a front surface of the interposer.
18. The filter device of claim 17 , wherein
the interposer comprises a silicon base, and
the vias are through silicon vias (TSVs).
19. The filter device of claim 17 , wherein the interposer is a printed circuit board.
20. The filter device of claim 17 , wherein the interposer is a low temperature co-fired ceramic circuit card.
21. The filter device of claim 13 , further comprising:
a plurality of recesses in the back surface of the interposer facing the plurality of diaphragms.
22. The filter device of claim 13 , wherein each of the plurality of recesses has a depth such that a distance from a bottom of each recess to the respective diaphragm is greater than or equal to 15 microns and less than or equal to 100 microns.
23. The filter device of claim 13 , wherein the plurality of IDTs and the at least one piezoelectric plate are configured such that respective radio frequency signals applied to each of the plurality of IDTs excite bulk shear acoustic waves in the respective diaphragms.