CN211378248U

CN211378248U - Piezoelectric MEMS microphone

Info

Publication number: CN211378248U
Application number: CN201922502174.9U
Authority: CN
Inventors: 石正雨; 童贝; 李杨
Original assignee: AAC Acoustic Technologies Shenzhen Co Ltd
Current assignee: AAC Technologies Holdings Shenzhen Co Ltd
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-08-28
Anticipated expiration: 2029-12-31

Abstract

The utility model provides a piezoelectric MEMS microphone, which comprises a substrate with a back cavity and at least one cantilever beam fixed on the substrate; the cantilever beam comprises a fixed part fixed on the substrate and a vibrating part extending from the fixed part and suspended in the back cavity; the cantilever beam includes two at least layers of sound sensor layer and presss from both sides and locates two adjacent structural layer between the sound sensor layer along the vibration direction, the sound sensor layer includes first electrode layer, second electrode layer and locates first electrode layer with the piezoelectric layer between the second electrode layer. The utility model discloses a through set up the structural layer between the acoustic sensor layer for the radius of curvature of cantilever beam is bigger, will produce bigger meeting an emergency when producing the same bending angle, thereby produces bigger output.

Description

Piezoelectric MEMS microphone

[ technical field ] A method for producing a semiconductor device

The utility model relates to a piezoelectricity MEMS microphone field.

[ background of the invention ]

The existing cantilever beam structure of 3 layers (electrode/piezoelectric material/electrode) or 5 layers (electrode/piezoelectric material/electrode) of the piezoelectric microphone has the problems that the cantilever beam amplitude is large, and the piezoelectric material strain is not large, so that the electric signal output is not enough.

Therefore, there is a need to provide a piezoelectric microphone that solves the above problems.

[ Utility model ] content

An object of the utility model is to provide a piezoelectric MEMS microphone aims at producing bigger meeting an emergency to produce bigger output.

The technical scheme of the utility model as follows:

a piezoelectric MEMS microphone, comprising:

a substrate having a back cavity;

at least one cantilever beam fixed to the base;

the cantilever beam comprises a fixed part fixed on the substrate and a vibrating part extending from the fixed part and suspended in the back cavity;

the cantilever beam includes two at least layers of sound sensor layer and presss from both sides and locates two adjacent structural layer between the sound sensor layer along the vibration direction, the sound sensor layer includes first electrode layer, second electrode layer and locates first electrode layer with the piezoelectric layer between the second electrode layer.

Further, the structural layer has a young's modulus that is less than the acoustic sensor layer.

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

Further, the structural layer has a thickness greater than the acoustic sensor layer.

Further, the fixed part is of an annular structure, at least two vibration parts are arranged at intervals along the circumferential direction of the fixed part, and each vibration part converges from the fixed part to the center of the fixed part.

Further, still including the suspension in the balancing portion of back of the body chamber and connect the balancing portion with the elastic connection spare between the vibration portion, the vibration portion is around locating the balancing portion and being located the balancing portion with between the fixed part.

Further, the vibration portion include with the fixed extension of fixed part and around establishing the extension periphery and with the vibration arm of fixed part interval setting, the vibration arm include with the extension is kept away from the fixed first vibration arm of one side of fixed part and certainly first vibration arm towards the fixed part is buckled and is extended and is located the alar part of extension both sides, the alar part with the extension interval sets up.

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

Furthermore, the elastic connecting piece comprises an elastic arm positioned between the balance part and the vibration part and connecting arms respectively bent and extended from two opposite end parts of the elastic arm to the balance part or the vibration part, and the extending directions of the two connecting arms are opposite.

Furthermore, the balance part or the vibration part is correspondingly provided with an avoiding groove for avoiding the elastic connecting piece.

Furthermore, the balance part is polygonal, and each vibration part is correspondingly connected to each side of the balance part.

The beneficial effects of the utility model reside in that: by providing a structural layer between the acoustic sensor layers, the radius of curvature of the cantilever is made larger, which will produce more strain when the same bending angle is produced, resulting in a larger output.

[ description of the drawings ]

Fig. 1 is a schematic structural diagram of a piezoelectric MEMS microphone according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along A-A of FIG. 1;

fig. 3 is a partially enlarged view of B in fig. 1.

In the figure:

100. a piezoelectric MEMS microphone; 1. a substrate; 10. a back cavity; 11. a cantilever beam; 2. an acoustic sensor layer; 21. a first electrode layer; 22. a second electrode layer; 23. a piezoelectric layer; 3. an insulating structure layer; 211. a fixed part; 212. a vibrating section; 213. a balancing section; 214. an elastic connecting member; 215. an extension portion; 216. a vibrating arm; 2161. a first vibrating arm; 2162. a wing portion; 2141. a spring arm; 2142. a connecting arm; 210. avoiding the groove.

[ detailed description ] embodiments

The present invention will be further described with reference to the accompanying drawings and embodiments.

Referring to fig. 1 and 2, a piezoelectric MEMS microphone 100 includes:

a substrate 1 having a back cavity 10;

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

the cantilever beam 11 comprises a fixed part 211 fixed on the substrate 1 and a vibrating part 212 extending from the fixed part 211 and suspended in the back cavity 10;

the cantilever beam 11 comprises at least two layers of acoustic sensor layers 2 and a structural layer 3 clamped between two adjacent acoustic sensor layers 2 along the vibration direction, wherein the acoustic sensor layers 2 comprise a first electrode layer 21, a second electrode layer 22 and a piezoelectric layer 23 arranged 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 larger strain is generated when the same bending angle is generated, and larger output is generated.

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 producing 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. Further, the radius of curvature of the cantilever beam 11 is made larger, which results in a larger strain and thus a larger output when the same bending angle is produced.

Preferably, the thickness of the insulating structure layer 3 is greater than that of the acoustic sensor layer 2. Further, the radius of curvature of the cantilever beam 11 is made larger, which results in a larger strain and thus a larger output when the same bending angle is produced.

Preferably, the fixing portion 211 is a ring structure, at least two of the vibrating portions 212 are disposed at intervals along a circumferential direction of the fixing portion 211, and each of the vibrating portions 212 converges from the fixing portion 211 toward a center of the fixing portion 211.

Preferably, the back cavity further comprises a balance part 213 suspended in the back cavity 10 and an elastic connecting piece 214 connected between the balance part 213 and the vibration part 212, wherein the vibration part 212 is wound on the balance part 213 and is located between the balance part 213 and the fixing part 211. The balance part 213 is arranged to further avoid the free end of the vibration part 212 from warping under the action of sound pressure, so that the vibration part 212 at the anchoring part is stressed to generate an electric signal, and the vibration part 212 is distributed along the circumferential direction of the balance part 213. 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.

Preferably, the vibration portion 212 includes an extension portion 215 fixed to the fixing portion 211 and a vibration arm 216 wound around the extension portion 215 and spaced from the fixing portion 211, the vibration arm 216 includes a first vibration arm 2161 fixed to a side of the extension portion 215 away from the fixing portion 211 and a wing portion 2162 bent and extended from the first vibration arm 2161 toward the fixing portion 211 and located at two sides of the extension portion 215, and the wing portion 2162 is spaced from the extension portion 215. In this way, compactness and structural consistency are improved.

It is preferable that the first electrode layer 21 of the extension portion 215 and the first electrode layer 21 of the vibration arm 216 are insulated from each other. The extension portion 215 and the vibrating arm 216 are insulated from each other, so that the extension portion 215 forms an electrode. As shown in fig. 1, the extension portion 215 and the vibrating arm 216 are insulated from each other by surface layer etching, but are not separated from each other as a whole, so that different electrode sensing regions can be provided in the extension portion 215 while ensuring vibration as a whole.

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

Preferably, the balance portion 213 or the vibration portion 212 is provided with an escape groove 210 for escaping from the elastic connection 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 of the vibration portions 212 is correspondingly connected to each side of the balance portion 213.

The above embodiments of the present invention are only described, and it should be noted that, for those skilled in the art, modifications can be made without departing from the inventive concept, but these all fall into the protection scope of the present invention.

Claims

1. A piezoelectric MEMS microphone, comprising:

a substrate having a back cavity;

at least one cantilever beam fixed to the base;

2. A piezoelectric MEMS microphone as defined in claim 1, wherein: the structural layer has a Young's modulus less than the acoustic sensor layer.

3. A piezoelectric MEMS microphone as defined in claim 1, wherein: the thickness of the structural layer is greater than the thickness of the first electrode layer and the thickness of the piezoelectric layer.

4. A piezoelectric MEMS microphone as defined in claim 3, wherein: the structural layer has a thickness greater than the acoustic sensor layer.

5. A piezoelectric MEMS microphone as defined in claim 1, wherein: the fixed part is of an annular structure, at least two vibration parts are arranged at intervals along the circumferential direction of the fixed part, and each vibration part converges from the fixed part to the center of the fixed part.

6. Piezoelectric MEMS microphone according to claim 5, characterized in that: still including the suspension in the balancing portion of back of the body chamber and connect the balancing portion with elastic connection spare between the vibration portion, the vibration portion is around locating the balancing portion just is located the balancing portion with between the fixed part.

7. A piezoelectric MEMS microphone as claimed in claim 6, wherein: the vibrating part include with the fixed extension of fixed part and around establishing the extension periphery and with the vibration arm that the fixed part interval set up, the vibration arm include with the extension is kept away from the fixed first vibration arm of one side of fixed part and certainly first vibration arm court the fixed part is buckled and is extended and be located the alar part of extension both sides, the alar part with the extension interval sets up.

8. Piezoelectric MEMS microphone according to claim 7, characterized in that: the first electrode layer of the extension portion and the first electrode layer of the vibration arm are insulated from each other.

9. A piezoelectric MEMS microphone as defined in claim 8, wherein: the elastic connecting piece comprises elastic arms located between the balance part and the vibration part and connecting arms respectively extending to the balance part or the vibration part from two opposite end parts of the elastic arms in a bending mode, and the extending directions of the two connecting arms are opposite.

10. A piezoelectric MEMS microphone as defined in claim 9, wherein: the balance part or the vibration part is correspondingly provided with an avoiding groove for avoiding the elastic connecting piece.

11. A piezoelectric MEMS microphone as defined in claim 8, wherein: the balance part is polygonal, and each vibration part is correspondingly connected to each side of the balance part.