Bulk-acoustic wave resonator

Patent metadata

Field	Value
Publication number	US-11595022-B2
Application number	US-202016898835-A
Country	US
Kind code	B2
Filing date	Jun 11, 2020
Priority date	Jul 31, 2019
Publication date	Feb 28, 2023
Grant date	Feb 28, 2023

Abstract

A bulk-acoustic wave resonator includes: a substrate; a lower electrode disposed on the substrate; a piezoelectric layer at least partially covering the lower electrode; and an upper electrode at least partially covering the piezoelectric layer. On a surface of the bulk-acoustic wave resonator, a centroid of an active area in which the lower electrode, the piezoelectric layer, and the upper electrode all overlap each other is aligned with a center of a rectangle defining an aspect ratio of the active area. The active area has a shape of a polygon symmetrical with respect to at least one axis passing through the center of the rectangle defining the aspect ratio. The aspect ratio is greater than or equal to 2 and less than or equal to 10.

First claim

What is claimed is:

1. A bulk-acoustic wave resonator, comprising:
a substrate;
a lower electrode disposed on the substrate;
a piezoelectric layer at least partially covering the lower electrode;
an upper electrode at least partially covering the piezoelectric layer;
an etch-preventing portion; and
a sacrificial layer disposed outside of the etch-preventing portion,
wherein, on a surface of the bulk-acoustic wave resonator, a centroid of an active area in which the lower electrode, the piezoelectric layer, and the upper electrode all overlap each other is aligned with a center of a rectangle defining an aspect ratio of the active area,
wherein the active area has a shape of a polygon symmetrical with respect to at least one axis passing through the center of the rectangle defining the aspect ratio, and
wherein the aspect ratio is greater than or equal to 2 and less than or equal to 10.

2. The bulk-acoustic wave resonator according to claim 1 , wherein the rectangle defining the aspect ratio is a rectangle having a largest aspect ratio among rectangles contacting three or more vertices of the polygon.

3. The bulk-acoustic wave resonator according to claim 1 , wherein the polygon is a polygon having N angles, wherein N is an even number greater than or equal to 4.

4. The bulk-acoustic wave resonator according to claim 1 , further comprising a membrane layer forming a cavity together with the substrate.

5. The bulk-acoustic wave resonator according to claim 4 , wherein the etch-preventing portion is disposed to surround the cavity.

6. The bulk-acoustic wave resonator according to claim 1 , further comprising an insertion layer at least partially disposed between the lower electrode and the piezoelectric layer.

7. The bulk-acoustic wave resonator according to claim 1 , further comprising a passivation layer disposed to expose a portion of the lower electrode and a portion of the upper electrode.

8. The bulk-acoustic wave resonator according to claim 7 , further comprising a metal pad contacting the exposed portion of the lower electrode and the exposed portion of the upper electrode.

9. A bulk-acoustic wave resonator, comprising:
a substrate;
a lower electrode disposed on the substrate;
a piezoelectric layer at least partially covering the lower electrode; and
an upper electrode at least partially covering the piezoelectric layer,
wherein a centroid of an active area in which the lower electrode, the piezoelectric layer, and the upper electrode all overlap each other matches a first axis coordinate value of a center of a rectangle defining an aspect ratio of the active area, and the centroid of the active area mismatches a second axis coordinate value of the center of the rectangle defining the aspect ratio of the active area, the first axis coordinate value being a coordinate value with respect to a first axis of the rectangle defining the aspect ratio, and the second axis coordinate value being a coordinate value with respect to a second axis of the rectangle defining the aspect ratio, and
wherein the bulk-acoustic wave resonator satisfies y′/h<0.067, y′ being a separation distance between the centroid of the active area and the center of the rectangle in a direction of the second axis, and h being a length of the active area in the direction of the second axis.

10. The bulk-acoustic wave resonator according to claim 9 , wherein the active area is symmetrical with respect to the first axis.

11. The bulk-acoustic wave resonator according to claim 9 , wherein the rectangle defining the aspect ratio is a rectangle having a largest aspect ratio among rectangles contacting three or more vertices of a perimeter shape of the active area.

12. The bulk-acoustic wave resonator according to claim 9 , further comprising an insertion layer partially disposed between the lower electrode and the piezoelectric layer.

13. The bulk-acoustic wave resonator according to claim 12 , wherein the insertion layer has a ring shape.

14. A bulk-acoustic wave resonator, comprising:
a lower electrode disposed on a substrate;
a piezoelectric layer disposed on the lower electrode; and
an upper electrode disposed on the piezoelectric layer,
wherein a perimeter of an active area in which the lower electrode, the piezoelectric layer, and the upper electrode all overlap each other has a shape of a polygon symmetrical with respect to at least one axis passing through a center of a rectangle defining an aspect ratio of the polygon,
wherein a centroid of the polygon is aligned with the center of the rectangle defining the aspect ratio, and
wherein the aspect ratio is greater than or equal to 2 and less than or equal to 10.

15. The bulk acoustic resonator of claim 14 , wherein the at least one axis includes only one axis.

16. The bulk acoustic resonator of claim 14 , wherein the polygon is either one of a rhombus, a hexagon, and an octagon.

17. The bulk-acoustic wave resonator of claim 14 , wherein the aspect ratio is greater than or equal to 2.4 and less than or equal to 5.6.

18. The bulk-acoustic resonator of claim 14 , wherein the rectangle defining the aspect ratio is a rectangle having a largest aspect ratio among rectangles contacting three or more vertices of the polygon.

19. A bulk-acoustic wave resonator, comprising:
a lower electrode disposed on a substrate;
a piezoelectric layer disposed on the lower electrode; and
an upper electrode disposed on the piezoelectric layer,
wherein an active area in which the lower electrode, the piezoelectric layer, and the upper electrode all overlap each other has a shape of a polygon,
wherein a centroid of the polygon matches a first axis coordinate value of a center of a rectangle defining an aspect ratio of the polygon, and the centroid of the active area mismatches a second axis coordinate value of the center of the rectangle defining the aspect ratio of the polygon, the first axis coordinate value being a coordinate value with respect to a first axis of the rectangle defining the aspect ratio, and the second axis coordinate value being a coordinate value with respect to a second axis of the rectangle defining the aspect ratio, and
wherein the bulk-acoustic wave resonator satisfies y′/h<0.067, y′ being a separation distance between the centroid of the active area and the center of the rectangle in a direction of the second axis, and h being a length of the active area in the direction of the second axis.

20. The bulk acoustic wave resonator of claim 19 , wherein the active area is symmetrical with respect to the first axis.

21. The bulk acoustic wave resonator of claim 19 , wherein the polygon is a hexagon.

Assignees

• Samsung Electro Mech

Inventors

• Han Won
• Kim Sung Wook
• Jeong Dae Hun
• Son Sang Uk
• Han Sang Heon
• Ryou Jeong Hoon

Classifications

• H03H9/132 Primary

  characterized by a particular shape · CPC title

• H03H9/17

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

• H03H9/05

  Holders or supports · CPC title

• H03H9/173

  Air-gaps · CPC title

• H03H9/25

  Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} · CPC title