Bulk acoustic wave filter structure with conductive bridge forming electrical loop with an electrode

Patent metadata

Field	Value
Publication number	US-11528007-B2
Application number	US-202117176476-A
Country	US
Kind code	B2
Filing date	Feb 16, 2021
Priority date	Oct 26, 2020
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.

First claim

What is claimed is:

1. A bulk acoustic wave (BAW) filter structure, comprising:
a substrate;
at least one transducer over the substrate, the at least one transducer comprising:
a bottom electrode comprising a first electrical medial end and a first electrical distal end,
a top electrode,
a piezoelectric layer between the bottom electrode and the top electrode, and
a first conductive bridge offset from at least a portion of the bottom electrode by a first insulating volume,
wherein the first conductive bridge is electrically connected to the first electrical medial end and the first electrical distal end to form a first electrical loop between the first electrical medial end and the first electrical distal end of the bottom electrode.

2. The BAW filter structure of claim 1 , wherein the bottom electrode comprises a first active region portion, a first medial via portion external to the first active region portion and aligned with a first medial via, and a first distal via portion external to the first active region portion and aligned with a first distal via, the first medial via portion being a greater size than the first distal via portion.

3. The BAW filter structure of claim 2 , wherein the first medial via portion comprises a plurality of first medial via portions separated from each other by at least one first gap.

4. The BAW filter structure of claim 2 , wherein the first distal via portion comprises a single first distal via portion.

5. The BAW filter structure of claim 2 , wherein the first distal via portion comprises a plurality of first distal via portions separated from each other by a gap.

6. The BAW filter structure of claim 1 ,
further comprising a second conductive bridge offset from at least a portion of the top electrode by a second insulating volume,
wherein the top electrode comprises a second electrical medial end and a second electrical distal end,
wherein the second conductive bridge is electrically connected to the second electrical medial end and the second electrical distal end to form a second electrical loop between the second electrical medial end and the second electrical distal end of the top electrode.

7. The BAW filter structure of claim 6 , wherein the first insulating volume comprises at least a portion of a first Bragg reflector, and the second insulating volume comprises at least a portion of a second Bragg reflector.

8. The BAW filter structure of claim 6 ,
wherein the bottom electrode comprises a first active region portion, a first medial via portion aligned with a first medial via, and a first distal via portion aligned with a first distal via, the first medial via portion being a greater size than the first distal via portion;
wherein the top electrode comprises a second active region portion, a second medial via portion aligned with a second medial via, and a second distal via portion aligned with a second distal via, the second medial via portion being a greater size than the second distal via portion;
wherein the first distal via portion comprises a single first distal via portion;
wherein the first medial via portion comprises a plurality of first medial via portions separated from each other by a first gap;
wherein the second distal via portion comprises a single second distal via portion;
wherein the second medial via portion comprises a plurality of second medial via portions separated from each other by a second gap; and
wherein the single first distal via portion vertically aligns with the second gap, and the single second distal via portion vertically aligns with the first gap.

9. The BAW filter structure of claim 6 ,
wherein the bottom electrode comprises a first active region portion, a first medial via portion aligned with a first medial via, and a first distal via portion aligned with a first distal via, the first medial via portion being a greater size than the first distal via portion;
wherein the top electrode comprises a second active region portion, a second medial via portion aligned with a second medial via, and a second distal via portion aligned with a second distal via, the second medial via portion being a greater size than the second distal via portion;
wherein the first distal via portion comprises a plurality of first distal via portions;
wherein the first medial via portion comprises a plurality of first medial via portions separated from each other by a first plurality of gaps;
wherein the second distal via portion comprises a single second distal via portion;
wherein the second medial via portion comprises a plurality of second medial via portions separated from each other by a second plurality of gaps; and
wherein each of the first distal via portions vertically aligns with one of the second plurality of gaps, and each of the second distal via portions vertically aligns with one of the second plurality of gaps.

10. The BAW filter structure of claim 1 , wherein the first conductive bridge comprises:
a span portion,
a first medial conductive via electrically connecting the span portion to the first electrical medial end of the bottom electrode, and
a first distal conductive via electrically connecting the span portion to the first electrical distal end of the bottom electrode.

11. The BAW filter structure of claim 10 , wherein the first conductive bridge further comprises first side conductive vias extending between the first medial conductive via and the first distal conductive via to enclose the first insulating volume between the span portion and the bottom electrode.

12. The BAW filter structure of claim 1 ,
wherein the BAW filter structure comprises a coupled-resonator filter (CRF) structure; and
wherein the at least one transducer includes a first plurality of horizontally adjacent transducers, each of the first plurality of horizontally adjacent transducers including the first conductive bridge.

13. The BAW filter structure of claim 12 , further comprising a second plurality of horizontally adjacent transducers positioned above the first plurality of horizontally adjacent transducers with the first conductive bridge positioned between the first plurality of horizontally adjacent transducers and the second plurality of horizontally adjacent transducers.

14. The BAW filter structure of claim 1 , wherein the first conductive bridge comprises:
a span portion,
peripheral conductive vias enclosing the first insulating volume; and
internal conductive vias within the first insulating volume enclosed by the peripheral conductive vias.

15. The BAW filter structure of claim 1 , wherein the first insulating volume comprises an air cavity.

16. The BAW filter structure of claim 1 , wherein the first insulating volume comprises at least a portion of a first Bragg reflector.

17. The BAW filter structure of claim 1 ,
further comprising a first Bragg reflector positioned proximate the bottom electrode, the first Bragg reflector comprising a proximate metallic layer;
wherein the first conductive bridge comprises metallic vias extending between the bottom electrode and the proximate metallic layer of the first Bragg reflector.

18. The BAW filter structure of claim 1 , wherein the bottom electrode comprises a first active region portion, a first medial via portion external to the first active region portion and aligned with a first medial via, and a first distal via portion within the first active region portion and aligned with a first distal via.

19. The BAW filter structure of claim 1 ,
wherein the BAW filter structure comprise

Assignees

• Qorvo Us Inc

Inventors

• Yusuf Yazid
• Modarres-Zadeh Mohammad J
• Tag Andreas
• Stokes Paul
• Aigner Robert
• Fattinger Gernot

Classifications

• H03H9/13

  for networks consisting of piezoelectric or electrostrictive materials (for networks using surface acoustic waves H03H9/145) · CPC title

• H03H9/17

  having a single resonator (crystal tuning forks H03H9/21) · CPC title

• H03H9/02086

  Means for compensation or elimination of undesirable effects · CPC title

• H03H9/131 Primary

  consisting of a multilayered structure · CPC title

• H03H9/564

  implemented with thin-film techniques · CPC title