WO2022110442A1

WO2022110442A1 - Piezoelectric mems microphone

Info

Publication number: WO2022110442A1
Application number: PCT/CN2020/139422
Authority: WO
Inventors: 童贝; 石正雨; 沈宇; 段炼
Original assignee: 瑞声声学科技(深圳)有限公司
Priority date: 2020-11-30
Filing date: 2020-12-25
Publication date: 2022-06-02
Also published as: CN214154838U

Abstract

The present application provides a piezoelectric MEMS microphone, comprising at least one piezoelectric MEMS unit. The piezoelectric MEMS unit comprises: a substrate, which comprises an annular peripheral wall defining an accommodation cavity, and a support structure arranged in the accommodation cavity; and a film structure, which is partially fixed to the support structure. The support structure comprises a support portion that is arranged spaced apart from the peripheral wall, and several extending arms extending to the support portion from the peripheral wall, wherein one end of each extending arm is connected to the support portion, and the other end thereof is connected to the peripheral wall so as to divide the accommodation cavity into several cavities; and a through hole penetrating the support portion is formed in the support portion in a vibration direction. The support structure in the present application comprises a support portion that is arranged spaced apart from the peripheral wall, and several extending arms extending to the support portion from the peripheral wall. The sound pressure at an air inlet is improved by providing a through hole in the support portion.

Description

Piezoelectric MEMS Microphone

technical field

The present application relates to the technical field of acoustics and electricity, and in particular, to a piezoelectric MEMS microphone.

Background technique

The existing piezoelectric MEMS unit includes a base, a support and a piezoelectric diaphragm, wherein the support includes four support beam structures and a support column, and the piezoelectric diaphragm includes four cantilever beam diaphragms corresponding to the support beam structures , the piezoelectric diaphragm is fixed on the support column at the center of the base, and the end of the cantilever beam diaphragm is warped under the action of sound pressure, so that the piezoelectric layer in the piezoelectric diaphragm is stressed to generate voltage output. The area is large, and the piezoelectric diaphragm above the support column has almost no voltage output; in addition, when the patch is placed on the PCB, it will affect the entry of the sound pressure of the air inlet.

technical problem

The purpose of the present application is to provide a MEMS microphone chip that improves the sound pressure of the air inlet and further improves the sensitivity.

technical solutions

In order to achieve the above purpose, the present application provides a piezoelectric MEMS microphone, comprising at least one piezoelectric MEMS unit, the piezoelectric MEMS unit comprising: a substrate, including an annular peripheral wall surrounding a receiving cavity and a the supporting structure; the diaphragm structure is partially fixed to the supporting structure; the supporting structure includes a supporting portion spaced from the peripheral wall and a number of extension arms extending from the peripheral wall to the supporting portion; the One end of the extension arm is connected to the support part, and the other end is connected to the peripheral wall to divide the receiving cavity into several cavities; the support part is formed with a through hole penetrating the support part along the vibration direction.

Preferably, the base includes a first substrate, the receiving cavity includes a first cavity formed on the first substrate, the peripheral wall includes a first peripheral wall surrounding the first cavity, and the support The portion includes a first support portion disposed in the first cavity and spaced apart from the first peripheral wall, and a plurality of the extension arms include a plurality of first support portions extending from the first peripheral wall to the first support portion. An extension arm, the through hole includes a first through hole formed along the vibration direction and penetrating the first support portion.

Preferably, the base further includes an isolation layer disposed between the first substrate and the diaphragm structure, and the projection profile of the isolation layer along the vibration direction is the same as that of the first substrate along the vibration direction. The projected contour shape of .

Preferably, the diaphragm structure is an integrated structure, including a fixed area and several movable parts, the fixed area includes an anchor part and several anchor arms radially extending from the edge of the anchor part, so The anchor portion is fixed to the support portion, the anchor arm is fixed to the extension arm, and each movable portion surrounds the anchor portion and is spaced from the anchor arm.

Preferably, the fixed area is provided above the support structure, and the movable portion falls into the cavity along the orthographic projection of the axial direction of the base.

Preferably, the diaphragm structure includes a first electrode layer, a first piezoelectric layer and a second electrode layer stacked in sequence along the vibration direction, and the first electrode layer is disposed on the diaphragm structure close to the support structure. side.

Preferably, the diaphragm structure further includes a second piezoelectric layer stacked on a side of the second electrode layer away from the first piezoelectric layer, and a second piezoelectric layer stacked on the second piezoelectric layer the third electrode layer.

Preferably, a plurality of the piezoelectric MEMS units are distributed in an array structure.

beneficial effect

The beneficial effect of the present application is to provide a piezoelectric MEMS microphone, the support structure of which includes a support portion spaced from a peripheral wall and a plurality of extension arms extending from the peripheral wall to the support portion; by arranging through holes in the support portion The sound pressure of the air intake is improved, and the sensitivity is further improved.

Description of drawings

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

2 is a front view of a piezoelectric MEMS unit according to an embodiment of the present invention;

3 is a perspective view of a piezoelectric MEMS unit according to an embodiment of the present invention;

4 is a bottom view of a piezoelectric MEMS unit according to an embodiment of the present invention;

5 is a cross-sectional view along the A-A direction in FIG. 3;

6 is a schematic structural diagram of a substrate according to an embodiment of the present invention;

7 is a perspective view of a substrate according to an embodiment of the present invention;

8 is a schematic structural diagram of a first substrate according to an embodiment of the present invention;

9 is a schematic structural diagram of an isolation layer according to an embodiment of the present invention;

10 is a schematic structural diagram of a diaphragm structure according to an embodiment of the present invention;

11 is a schematic structural diagram of a first electrode layer according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of a first piezoelectric layer according to an embodiment of the present invention.

Embodiments of the present invention

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

It should be noted that all directional indications (such as up, down, left, right, front, back, inside, outside, top, bottom...) in the embodiments of the present application are only used to explain the As shown in the figure), the relative positional relationship between the components, etc., if the specific posture changes, the directional indication also changes accordingly.

1 to 12, the present application provides a piezoelectric MEMS microphone. The piezoelectric MEMS microphone includes several piezoelectric MEMS units 1, and the several piezoelectric MEMS units 1 are distributed in an array structure. There are four MEMS units 1, which are distributed in a 2*2 array structure. Of course, to ensure a certain sensitivity or signal-to-noise ratio, the piezoelectric MEMS unit 1 can also be a 3*3 array structure distribution, a 4*4 array structure distribution, or More array-like structures.

Referring to FIG. 1 to FIG. 5 , the piezoelectric MEMS unit 1 includes a substrate 10 and a diaphragm structure 30 . The square substrate 10 has a receiving cavity 101 ; the diaphragm structure 30 is formed above the substrate 10 .

Referring to FIGS. 6 and 7 , the base 10 includes an annular peripheral wall 102 surrounding the receiving cavity 101 and a supporting structure disposed in the receiving cavity 101 ; the supporting structure includes a supporting portion 103 disposed at intervals from the peripheral wall 102 and a self-supporting structure. The peripheral wall 102 extends to a plurality of extending arms 104 of the support portion 103 , wherein the support portion 103 is disposed at the center of the receiving cavity 101 . One end of the extension arm 104 is connected to the support portion 103 , and the other end of the extension arm 104 is connected to the peripheral wall 102 to divide the receiving cavity 101 into a plurality of cavities 105 spaced along the circumference of the extension arm 104 .

The base 10 includes a first substrate 11 and an isolation layer 12 disposed between the first substrate 11 and the diaphragm structure 30 .

Referring to FIG. 8 , the first substrate 11 includes a first peripheral wall 112 surrounding the first cavity 111 , a first supporting portion 113 disposed in the first cavity 111 and spaced from the first peripheral wall 112 , and a first supporting portion 113 from the first peripheral The wall 112 extends to the first extension arm 114 of the first support portion 113, the first support portion 113 is arranged at the center of the first cavity 111, and the first support portion 113 and the first extension arm 114 constitute a first support structure; One end of an extension arm 114 is connected to the first support portion 113 , and the other end of the first extension arm 114 is connected to the first peripheral wall 112 to divide the first cavity 111 into a plurality of circumferential intervals along the first extension arm 114 The first sub-cavity 115 is provided; wherein, the first support portion 113 is formed with a first through hole 116 penetrating the first support portion 113 along the vibration direction, and the first through hole 116 is formed by etching.

Referring to FIG. 9 , the isolation layer 12 includes a second peripheral wall 122 surrounding the second cavity 121 , a second supporting portion 123 disposed in the second cavity 121 and spaced from the second peripheral wall 122 , and extending from the second peripheral wall 122 to The second extension arm 124 of the second support portion 123 is arranged at the center of the second cavity 121 , and the second support portion 123 and the second extension arm 124 constitute a second support structure; the second extension arm 124 One end of the second extending arm 124 is connected to the second supporting portion 123 , and the other end of the second extending arm 124 is connected to the second peripheral wall 122 , thereby dividing the second cavity 121 into a plurality of second sub-sections spaced along the circumferential direction of the second extending arm 124 Cavity 125; wherein, the second support portion 123 is formed with a second through hole 126 penetrating the second support portion 123 along the vibration direction, and the second through hole 126 is formed by etching.

The first cavity 111 communicates with the second cavity 121 to form the receiving cavity 101 , the first peripheral wall 112 and the second peripheral wall 122 are enclosed to form the annular peripheral wall 102 ; the first support portion 113 and the second support portion 123 are stacked to form a base. The support part 103, the first extension arm 114 and the second extension arm 124 form the extension arm 104 of the base, and the support part 103 and the extension arm 104 form a support structure; the first sub-cavity 115 communicates with the second sub-cavity 125 to form a cavity 105. The extension arm 104 can be used to provide certain support and protection to the diaphragm structure 30 when the diaphragm structure 30 is greatly deformed, so as to prevent the diaphragm structure 30 from being broken.

The first through hole 116 and the second through hole 126 form the through hole 106 of the support portion 103 , that is, the support portion 103 has a circular cylindrical structure; The force generates a voltage output, which further improves the overall sensitivity of the piezoelectric MEMS unit 1 and reduces the influence on the sound pressure entering the air inlet.

The diaphragm structure 30 is an integral structure, including a fixed area 301 and a plurality of movable parts 302, the fixed area 301 includes an anchoring part 303 and a plurality of anchoring arms 304 arranged at intervals, each of the anchoring arms 304 Formed radially extending from the edge of the anchor portion 303 , the anchor portion 303 is fixed to the support portion 103 , the anchor arm 304 is fixed to the extension arm 104 , and each movable portion 302 surrounds The anchoring portion 303 is spaced apart from the anchoring arm 304 .

The diaphragm structure 30 of the piezoelectric MEMS unit 1 is fixed on the supporting structure of the substrate 10 through the anchoring portion 303 and several anchoring arms 304 radially extending from the edge of the anchoring portion 303 , and the diaphragm structure is enlarged. The contact area between the film structure 30 and the substrate 10 is reduced, thereby effectively reducing the risk of peeling off the membrane structure 30 from the substrate 10 .

In this embodiment, the orthographic projection of the movable portion 302 along the axial direction of the base 10 falls into the cavity 105 . Specifically, a movable portion 302 is suspended above each cavity 105 , and the projected contour of each movable portion 302 in the direction perpendicular to the diaphragm structure 30 is located at the position of the corresponding cavity 105 in the direction perpendicular to the diaphragm structure 30 . within the projected contour.

In this embodiment, the projected contour of the inner side wall of the annular peripheral wall 102 in the direction perpendicular to the diaphragm structure 30 can be a circle or a polygon, and the number of the extension arms 104 can be set according to actual needs, and the specific number is not limited. As a preferred embodiment, the number of the extension arms 104 is four.

In this embodiment, the projected contours of the inner sidewall of the annular peripheral wall 102 and the outer sidewall of the support portion 103 in the base 10 in the direction perpendicular to the diaphragm structure 30 are both circular; the anchor portion 303 is in the direction perpendicular to the diaphragm structure 30 The projected outline of the anchor arm 304 in the direction perpendicular to the diaphragm structure 30 is in the shape of a strip; the projected outline of the single movable part 302 in the direction perpendicular to the diaphragm structure 30 is in the shape of a fan ring.

The diaphragm structure 30 is formed by stacking at least three layers of materials. Optionally, the diaphragm structure 30 includes a first electrode layer 31, a first piezoelectric layer 32, and a second electrode layer 33 that are stacked in sequence along the vibration direction; or, the diaphragm structure 30 includes sequentially stacked along the vibration direction. The first electrode layer 31, the first piezoelectric layer 32, the second electrode layer 33, the second piezoelectric layer 34 and the third electrode layer 35; , the same applies to this application. Wherein, the first electrode layer 31 is disposed on the side of the diaphragm structure 30 close to the support structure.

Referring to FIG. 11 , the first electrode layer 31 includes a first electrode sheet 311 located at the movable portion 302 , a second electrode sheet 312 located at the anchor portion 303 and a third electrode located at the anchor arm 304 The sheet 313, the first electrode sheet 311, the second electrode sheet 312, and the third electrode sheet 313 are spaced apart from each other, and have a circular structure as a whole. The second electrode layer 33 and the third electrode layer 35 have the same structure as the first electrode layer 31 .

The second electrode layer 33 includes a fourth electrode sheet located at the movable portion 302 , a fifth electrode sheet located at the anchor portion 303 and a sixth electrode sheet located at the anchor arm 304 . The electrode sheet, the fifth electrode sheet, and the sixth electrode sheet are spaced apart from each other.

The third electrode layer 35 includes a seventh electrode sheet located at the movable portion 302, an eighth electrode sheet located at the anchor portion 303, and a ninth electrode sheet located at the anchor arm 304. The seventh electrode sheet is located at the anchor arm 304. The electrode sheet, the eighth electrode sheet, and the ninth electrode sheet are spaced apart from each other.

Referring to FIG. 12 , the first piezoelectric layer 32 includes a first movable portion 321 located in the movable portion 302 and a first fixed region 322 located in the fixed region 301 . The first movable portion 321 is connected to the first movable portion 321 . A fixed area 322 is connected. The first piezoelectric layer 32 is integrally formed and has a circular structure as a whole, that is, the first movable portion 321 is connected to the first fixed region 322 , which improves the reliability of the diaphragm structure 30 . The second piezoelectric layer 34 has the same structure as the first piezoelectric layer 32 .

The second piezoelectric layer 34 includes a second movable portion located in the movable portion 302 and a second fixed region located in the fixed region 301 , and the second movable portion is connected to the second fixed region.

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

Claims

1. A piezoelectric MEMS microphone, comprising at least one piezoelectric MEMS unit, the piezoelectric MEMS unit comprising: a substrate, including an annular peripheral wall enclosing a receiving cavity and a support structure arranged in the receiving cavity; a diaphragm structure , which is partially fixed to the support structure; it is characterized in that: the support structure includes a support part spaced from the peripheral wall and a plurality of extension arms extending from the peripheral wall to the support part; One end is connected to the support part, and the other end is connected to the peripheral wall to divide the receiving cavity into several cavities; the support part is formed with a through hole penetrating the support part along the vibration direction.

2. The piezoelectric MEMS microphone according to claim 1, wherein the base comprises a first substrate, the receiving cavity comprises a first cavity formed on the first substrate, and the peripheral wall comprises a surrounding wall. The first peripheral wall of the first cavity, the support portion includes a first support portion disposed in the first cavity and spaced apart from the first peripheral wall, and a plurality of the extension arms include a plurality of extending arms from the The first peripheral wall extends to a plurality of first extension arms of the first support portion, and the through hole includes a first through hole formed through the first support portion along the vibration direction.

3. The piezoelectric MEMS microphone according to claim 2, wherein the base further comprises an isolation layer disposed between the first substrate and the diaphragm structure, and the isolation layer vibrates along the The projected profile of the direction has the same shape as the projected profile of the first substrate along the vibration direction.

4. The piezoelectric MEMS microphone according to claim 1, wherein the diaphragm structure is an integral structure, comprising a fixed area and a plurality of movable parts, and the fixed area includes an anchoring part and a self-anchoring part Several anchoring arms formed by radially extending from the edge of the part, the anchoring parts are fixed to the supporting part, the anchoring arms are fixed to the extending arms, and each movable part surrounds the anchoring part , and is spaced from the anchor arm.

5. The piezoelectric MEMS microphone according to claim 4, wherein the fixed area is disposed above the support structure, and the movable portion falls into the cavity along the orthographic projection of the axial direction of the substrate in vivo.

6. The piezoelectric MEMS microphone according to claim 4, wherein the diaphragm structure comprises a first electrode layer, a first piezoelectric layer and a second electrode layer stacked in sequence along the vibration direction, the first electrode layer The electrode layer is disposed on the side of the membrane structure close to the support structure.

7. The piezoelectric MEMS microphone according to claim 6, wherein the diaphragm structure further comprises a second piezoelectric layer stacked on a side of the second electrode layer away from the first piezoelectric layer. an electrical layer and a third electrode layer stacked on the second piezoelectric layer.

8. The piezoelectric MEMS microphone according to claim 7, wherein a plurality of the piezoelectric MEMS units are distributed in an array structure