WO2021134669A1

WO2021134669A1 - Piezoelectric mems microphone

Info

Publication number: WO2021134669A1
Application number: PCT/CN2019/130904
Authority: WO
Inventors: 石正雨; 童贝; 李杨
Original assignee: 瑞声声学科技(深圳)有限公司
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2021-07-08

Abstract

Provided in the present utility model is a piezoelectric MEMS microphone. The piezoelectric MEMS microphone comprises a substrate with a back cavity, and at least one cantilever beam fixed on the substrate. The cantilever beam comprises a fixed part which is fixed on the substrate and a vibration part which extends from the fixed part and is suspended in the back cavity. The cantilever beam comprises at least two acoustic sensor layers and a structural layer clamped between two adjacent acoustic sensor layers in a vibration direction. Each acoustic sensor layer comprises a first electrode layer, a second electrode layer, and a piezoelectric layer arranged between the first electrode layer and the second electrode layer. In the present utility model, the structural layer is arranged between the acoustic sensor layers, such that the curvature radius of the cantilever beam is larger, a larger strain is generated when the same bending angle is generated, and a larger output is thus generated.

Description

Piezo MEMS microphone

Technical field

The utility model relates to the field of piezoelectric MEMS microphones.

Background technique

The existing piezoelectric microphone has a 3-layer (electrode/piezoelectric material/electrode) or 5-layer (electrode/piezoelectric material/electrode/piezoelectric material/electrode) cantilever beam structure. There is a large cantilever beam amplitude and piezoelectric material strain The problem of insufficient electrical signal output due to small size.

Therefore, it is necessary to provide a piezoelectric microphone that solves the above-mentioned problems.

Summary of the invention

technical problem

The purpose of the utility model is to provide a piezoelectric MEMS microphone, which aims to generate greater strain, thereby generating greater output.

The solution to the problem

Technical solutions

The technical scheme of the utility model is as follows:

A piezoelectric MEMS microphone includes:

Substrate with back cavity;

At least one cantilever beam fixed to the base;

The cantilever beam includes a fixed part fixed on the base and a vibrating part extending from the fixed part and suspended in the back cavity;

The cantilever beam includes at least two acoustic sensor layers along the vibration direction and a structural layer sandwiched between two adjacent acoustic sensor layers. The acoustic sensor layer includes a first electrode layer, a second electrode layer, and The piezoelectric layer between the first electrode layer and the second electrode layer.

Further, the Young's modulus of the structural layer is smaller than that of the acoustic sensor layer.

Further, the thickness of the structure layer is greater than the thickness of the first electrode layer and the thickness of the piezoelectric layer.

Further, the thickness of the structural layer is greater than that of the acoustic sensor layer.

Further, the fixing portion has an annular structure, at least two of the vibration portions are arranged at intervals along the circumferential direction of the fixing portion, and each of the vibration portions converges from the fixing portion toward the center of the fixing portion.

Further, it further includes a balance part suspended in the back cavity and an elastic connecting piece connected between the balance part and the vibrating part, the vibrating part is arranged around the balance part and located at the balance part. Between 部 and said fixed portion.

Further, the vibrating portion includes an extension portion fixed to the fixed portion and a vibrating arm arranged around the outer circumference of the extension portion and spaced apart from the fixed portion, and the vibrating arm includes an extension portion away from the extension portion. A first vibrating arm fixed on one side of the fixing portion and wing portions bent and extending from the first vibrating arm toward the fixing portion and located on both sides of the extension portion, the wing portion being spaced from the extension portion Set up.

Further, the first electrode layer of the extension part and the first electrode layer of the vibrating arm are insulated from each other.

Further, the elastic connecting member includes an elastic arm located between the balance portion and the vibrating portion, and bending arms extending from opposite ends of the elastic arm to the balance portion or the vibrating portion, respectively The connecting arms, the extension directions of the two connecting arms are opposite.

Further, the balance part or the vibrating part is correspondingly provided with an escape groove for avoiding the elastic connecting member.

Further, the balance portion is polygonal, and each vibrating portion is respectively connected to each side of the balance portion.

The beneficial effects of the invention

Beneficial effect

The beneficial effect of the utility model is that the structure layer is arranged between the acoustic sensor layers, so that the radius of curvature of the cantilever beam is larger, and when the same bending angle is generated, greater strain will be generated, thereby generating greater output.

Brief description of the drawings

Description of the drawings

FIG. 1 is a schematic diagram of the structure of a piezoelectric MEMS microphone provided by an embodiment of the utility model;

Figure 2 is a cross-sectional view along A-A of Figure 1;

Fig. 3 is a partial enlarged view of B in Fig. 1.

In the picture:

100. Piezoelectric MEMS microphone; 1. Substrate; 10. Back cavity; 11. Cantilever beam; 2. Acoustic sensor layer; 21. First electrode layer; 22. Second electrode layer; 23. Piezoelectric layer; 3. Insulation Structural layer; 211, fixed part; 212, vibrating part; 213, balance part; 214, elastic connector; 215, extension part; 216, vibrating arm; 2161, first vibrating arm; 2162, wing part; 2141, elastic arm 2142. Connecting arm; 210. Avoidance slot.

Invention embodiment

Detailed ways

The present utility model will be further explained below in conjunction with the drawings and embodiments.

1 and 2, a piezoelectric MEMS microphone 100 includes:

A substrate 1 with a back cavity 10;

At least one cantilever beam 11 fixed to the base 1;

The cantilever beam 11 includes a fixed portion 211 fixed on the base 1 and a vibration portion 212 extending from the fixed portion 211 and suspended in the back cavity 10;

The cantilever beam 11 includes at least two acoustic sensor layers 2 along the vibration direction and a structural layer 3 sandwiched between two adjacent acoustic sensor layers 2. The acoustic sensor layer 2 includes a first electrode layer 21 and a first electrode layer 21. The second electrode layer 22 and the piezoelectric layer 23 provided between the first electrode layer 21 and the second electrode layer 22.

The insulating structure layer 3 is arranged between the two acoustic sensor layers 2 so that the radius of curvature of the cantilever beam 11 is larger, and greater strain will be generated when the same bending angle is generated, thereby generating a greater output.

Preferably, the Young's modulus of the structural layer 3 is lower than the first electrode layer 21 and the piezoelectric layer 23, so that the mechanical energy converted from acoustic energy is concentrated in the piezoelectric layer, thereby generating a larger output.

The thickness of the structural layer 3 is greater than the thickness of the first electrode layer 21 and the thickness of the piezoelectric layer 23. Furthermore, the radius of curvature of the cantilever beam 11 is larger, and greater strain will be generated when the same bending angle is generated, thereby generating a greater output.

Preferably, the thickness of the insulating structure layer 3 is greater than that of the acoustic sensor layer 2. Furthermore, the radius of curvature of the cantilever beam 11 is larger, and greater strain will be generated when the same bending angle is generated, thereby generating a greater output.

Preferably, the fixed portion 211 has an annular structure, at least two of the vibrating portions 212 are arranged at intervals along the circumferential direction of the fixed portion 211, and each of the vibrating portions 212 extends from the fixed portion 211 toward the center of the fixed portion 211 Converge.

Preferably, it further includes a balance portion 213 suspended in the back cavity 10 and an elastic connector 214 connected between the balance portion 213 and the vibrating portion 212, and the vibrating portion 212 is arranged around the balance portion 213. And it is located between the balance portion 213 and the fixed portion 211. The balance portion 213 is provided to further avoid warping of the free end of the vibrating portion 212 under the action of sound pressure, which causes the vibrating portion 212 at the anchoring portion to be forced to generate an electric signal, and the vibrating portion 212 is distributed along the circumferential direction of the balance portion 213. The Young's modulus of the structural layer 3 is lower than that of the first electrode layer 21 and the piezoelectric layer 23, so that the mechanical energy converted from acoustic energy is concentrated in the piezoelectric layer, thereby generating a larger output.

Preferably, the vibrating portion 212 includes an extension portion 215 fixed to the fixing portion 211 and a vibrating arm 216 arranged around the outer circumference of the extension portion 215 and spaced apart from the fixing portion 211, and the vibrating arm 216 includes The first vibrating arm fixed on the side of the extension portion 215 away from the fixing portion 211 is 2161 and the wings bent and extended from the first vibrating arm 2161 toward the fixing portion 211 and located on both sides of the extension portion 215 The wing portion 2162 and the extension portion 215 are spaced apart. In this way, the compactness and structural consistency are improved.

Preferably, the first electrode layer 21 of the extension portion 215 and the first electrode layer 21 of the vibrating arm 216 are insulated from each other. The extension 215 and the vibrating arm 216 are insulated from each other, so that the extension 215 can form an electrode. As shown in FIG. 1, the extension 215 and the vibrating arm 216 are insulated from each other by surface etching, but the whole is not separated, so that different electrode sensing regions can be provided in the extension 215 on the premise of ensuring that the whole is vibrated.

Preferably, the elastic connecting member 214 includes an elastic arm 2141 located between the balance portion 213 and the vibrating portion 212, and respectively bends and extends from opposite ends of the elastic arm 2141 to the balance portion 213 or For the connecting arms 2142 of the vibrating portion 212, the extension directions of the two connecting arms 2142 are opposite. The elastic connecting member 214 has a simple structure, is easy to process, has good consistency, and has good elasticity.

Preferably, the balance portion 213 or the vibrating portion 212 is correspondingly provided with an escape groove 210 for avoiding the elastic connecting member 214. The avoiding groove 210 is provided to accommodate the elastic connecting member 214, so that the structure is compact and the consistency is good.

Preferably, the balance portion 213 is polygonal, and each vibrating portion 212 is connected to each side of the balance portion 213 respectively.

The above are only the embodiments of the present utility model. It should be pointed out here that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present utility model, but these all belong to The scope of protection of the utility model.

Claims

A piezoelectric MEMS microphone is characterized in that it comprises:

Substrate with back cavity;

At least one cantilever beam fixed to the base;

The cantilever beam includes a fixed part fixed on the base and a vibrating part extending from the fixed part and suspended in the back cavity;

The cantilever beam includes at least two acoustic sensor layers along the vibration direction and a structural layer sandwiched between two adjacent acoustic sensor layers. The acoustic sensor layer includes a first electrode layer, a second electrode layer, and The piezoelectric layer between the first electrode layer and the second electrode layer.
The piezoelectric MEMS microphone according to claim 1, wherein the Young's modulus of the structural layer is smaller than that of the acoustic sensor layer.
The piezoelectric MEMS microphone according to claim 1, wherein the thickness of the structure layer is greater than the thickness of the first electrode layer and the thickness of the piezoelectric layer.
The piezoelectric MEMS microphone according to claim 3, wherein the thickness of the structure layer is greater than that of the acoustic sensor layer.
The piezoelectric MEMS microphone according to claim 1, wherein the fixed portion has a ring structure, at least two of the vibrating portions are arranged at intervals along the circumferential direction of the fixed portion, and each vibrating portion is separated from the The fixed part converges toward the center of the fixed part.
The piezoelectric MEMS microphone according to claim 5, further comprising a balance part suspended in the back cavity and an elastic connecting member connected between the balance part and the vibrating part, the vibration The part is wound around the balance part and located between the balance part and the fixed part.
The piezoelectric MEMS microphone according to claim 6, wherein the vibrating part includes an extension part fixed to the fixed part and a vibrating arm arranged around the periphery of the extension part and spaced apart from the fixed part , The vibrating arm includes a first vibrating arm fixed to a side of the extension part away from the fixing part, and a bending extension extending from the first vibrating arm toward the fixing part and located on both sides of the extension part. A wing part, the wing part and the extension part are spaced apart.
7. The piezoelectric MEMS microphone according to claim 6, wherein the first electrode layer of the extension portion and the first electrode layer of the vibrating arm are insulated from each other.
The piezoelectric MEMS microphone according to claim 8, wherein the elastic connecting member comprises an elastic arm located between the balance part and the vibrating part, and the elastic arm is bent from opposite ends of the elastic arm. The connecting arms that are folded to extend to the balance part or the vibrating part, the extension directions of the two connecting arms are opposite.
The piezoelectric MEMS microphone according to claim 9, wherein the balance part or the vibrating part is correspondingly provided with an escape groove for avoiding the elastic connecting member.
8. The piezoelectric MEMS microphone according to claim 8, wherein the balance portion is polygonal, and each vibrating portion is respectively connected to each side of the balance portion.