BRAGG MIRROR, RESONATOR AND FILTER DEVICE

• US 20190326881A1
• Filed: 07/03/2019
• Published: 10/24/2019
• Est. Priority Date: 01/05/2017
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: NURMELA, Arto Turo Ilmari, GU, Jian, WEI, Xiang
• Granted Patent: US 11,233,498 B2
• Time in Patent Office: Days
• CPC Class Codes: H03H 2003/025 the resonators or networks comprising an acoustic mirror
• CPC Class Codes: H03H 9/13 for networks consisting of piezoelectric or electrostrictive materials H03H9/145 takes precedence
• CPC Class Codes: H03H 9/17 having a single resonator crystal tuning forks H03H9/21
• CPC Class Codes: H03H 9/175 Acoustic mirrors

Abstract

Disclosed is a Bragg mirror, a resonator and a filter device comprised thereof. The Bragg mirror comprises a stack of plurality of layers arranged in an axial direction (A), wherein the plurality of layers comprises at least one first layer (L1) comprising, in a radial direction (r), a first material (M1) and a second material (M2), wherein the first material (M1) is a first metal and the second material (M2) is a different material with respect to the first material (M1), and wherein the first material (M1) is radially embedded by the second material (M2) in the first layer (L1), or vice versa. The resonator comprises a top electrode, a bottom electrode, a piezo electric layer arranged between the top electrode and the bottom electrode, a substrate, and a Bragg mirror arranged between the bottom electrode and the substrate.

Claims

1. A Bragg mirror comprising a stack of a plurality of layers arranged in an axial direction (A), wherein the plurality of layers comprises at least one first layer (L1) comprising, in a radial direction (r), a first material (M1) and a second material (M2), wherein the first material (M1) is a first metal and the second material (M2) is a different material with respect to the first material (M1), and wherein the first material (M1) is radially embedded by the second material (M2) in the first layer (L1), or wherein the second material (M2) is radially embedded by the first material (M1) in the first layer (L1).

2. The Bragg mirror according to claim 1, wherein a ratio of an acoustic velocity of the first material (M1) to an acoustic velocity of the second material (M2) is less than 0.94 or larger than 1.06.

3. The Bragg mirror according to claim 1, wherein a ratio of an acoustic impedance of the first material (M1) to an acoustic impedance of the second material (M2) is between 0.5 to 2.0.

4. The Bragg mirror according to claim 1, wherein the embedding material forms a loop surrounding the embedded material, and the embedded material (M1;

M2) forms a filling of the loop.

5. The Bragg mirror according to claim 1, wherein the plurality of layers comprises at least one second layer (L2) comprising a third material (M3), and at least one third layer (L3) comprising the first material (M1).

6. The Bragg mirror according to claim 5, wherein the third material (M3) is a second metal.

7. The Bragg mirror according to claim 6, wherein the first material (M1) is aluminium, the second material (M2) is silicon dioxide, and the third material (M3) is tungsten.

8. The Bragg mirror according to any of claim 5, wherein the plurality of layers comprises a plurality of said second layers (L2) and a plurality of said third layers (L3), wherein the plurality of second layers (L2) and the plurality of third layers (L3) are alternatingly arranged in the stack.

9. The Bragg mirror according to claim 8, wherein the plurality of second layers (L2) and the plurality of third layers (L3) are alternatingly arranged below the first layer (L1).

10. A resonator comprising:

a top electrode,

a bottom electrode,

a piezo electric layer arranged between the top electrode and the bottom electrode,

a substrate, and

the Bragg mirror according to claim 8, wherein the Bragg mirror is arranged between the bottom electrode and the substrate.

11. The resonator according to claim 10, wherein the top electrode in the axial direction overlaps the embedded material (M1;

M2).

12. The resonator according to claim 10, wherein the bottom electrode abuts the embedded material (M1;

M2).

13. The resonator according to any of claim 10, wherein a shape of the embedded material (M1;

M2) is the same shape as a shape of the top electrode.

14. The resonator according to any of claim 10, wherein a surface area of the embedded material (M1;

M2) is less than a surface area of the top electrode.

15. The resonator according to claim 14, wherein the surface area of the embedded material (M1;

M2) is between 67% to 98% of the surface area of the top electrode.

16. The resonator according to any of claim 10, wherein the top electrode, and the embedded material (M1;

M2) in the Bragg mirror are axially aligned relative to each other.

17. The resonator according to any of claim 10, wherein the bottom electrode abuts the first layer (L1).