WO2021134671A1

WO2021134671A1 - Piezoelectric mems microphone, and preparation method for piezoelectric mems microphone

Info

Publication number: WO2021134671A1
Application number: PCT/CN2019/130908
Authority: WO
Inventors: 童贝; 石正雨; 李杨
Original assignee: 瑞声声学科技(深圳)有限公司; 瑞声科技（南京）有限公司
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2021-07-08

Abstract

Provided are a piezoelectric MEMS microphone, and a preparation method for the piezoelectric MEMS microphone. The piezoelectric MEMS microphone comprises several piezoelectric MEMS units, each piezoelectric MEMS unit comprising a substrate, a support piece and a diaphragm structure; the substrate comprises an annular peripheral wall surrounding an accommodating cavity; the support piece comprises a suspended support portion arranged in the accommodating cavity and separated from the peripheral wall, and extension arms extended from the peripheral wall to the suspended support portion; the diaphragm structure is partially fixed on the suspended support portion, and the diaphragm structure is provided with an anchor portion connected to the suspended support portion, and a movable portion connected to the anchor portion and suspended in the accommodating cavity. By means of the arrangement of the support piece, the diaphragm structure of the piezoelectric MEMS unit is partially fixed on the suspended support portion arranged within the accommodating cavity formed by the substrate, thereby altering the anchor point position of the diaphragm structure, and reducing the degree of deformation of the support piece during bending of the diaphragm structure. In addition, the support piece can prevent a traditional back cavity etching process from affecting the diaphragm structure.

Description

Piezoelectric MEMS microphone and preparation method of piezoelectric MEMS microphone

【Technical Field】

The invention relates to the technical field of acoustic-electric conversion, in particular to a piezoelectric MEMS microphone and a preparation method of the piezoelectric MEMS microphone.

【Background technique】

The prior art piezoelectric MEMS microphone adopts the bending of the diaphragm 101 and the bending of the cantilever beam 102 to generate a relatively large stress at the position of the anchor point (as shown by the arrows in Figures 16 and 17), so that the pressure covering it is generated. The electric film is pressed to produce electric charge output; for the diaphragm structure, the stiffness will increase after covering the piezoelectric film at the anchor point, so the stress under the same pressure condition will be compared with that of the uncovered piezoelectric layer. There is a certain decrease, which leads to a decrease in output voltage, so the sensitivity of the structure is relatively low, and it is difficult to implement practical applications; for the cantilever structure, due to the existence of the film structure stress, the deformation of the cantilever beam will be large (micron level). And if there are multiple symmetrical cantilever beams in the structure, it is inevitable that the bending degree of the cantilever beams will be different, which puts forward higher requirements for subsequent packaging technology.

Therefore, it is necessary to provide a new piezoelectric MEMS microphone.

[Summary of the invention]

The first object of the present invention is to provide a piezoelectric MEMS microphone with high sensitivity and capable of reducing the deformation degree of the support member during the bending process of the diaphragm structure.

The technical scheme of the present invention is as follows:

A piezoelectric MEMS microphone includes at least one piezoelectric MEMS unit, and the piezoelectric MEMS unit includes:

The base includes an annular peripheral wall that encloses a receiving cavity;

The supporting member includes a suspension support part arranged in the receiving cavity and spaced apart from the peripheral wall, and an extension arm extending from the peripheral wall to the suspension support part;

The diaphragm structure is partially fixed to the suspension support portion, the diaphragm structure has an anchor portion fixed to the suspension support portion and a movable portion connected with the anchor portion, and the movable portion is along The axial orthographic projection of the substrate falls into the receiving cavity.

As an improvement, the base includes a first substrate located on a side of the movable part close to the support, the receiving cavity includes a first cavity formed on the first substrate, and the peripheral wall includes a surrounding The first peripheral wall of the first cavity, the extension arm extends from the first peripheral wall to the suspension support portion, and the suspension support portion is disposed in the first cavity and connected to the The first peripheral wall is arranged at intervals.

As an improvement, the side surface of the suspension support portion facing the diaphragm structure is flush with the side surface of the first substrate facing the diaphragm structure, and the diaphragm structure is suspended on the first substrate. Outside of a cavity.

As an improvement, the base further includes a second substrate stacked on the first substrate, the receiving cavity further includes a second cavity formed on the second substrate, and the peripheral wall further includes a surrounding On the second peripheral wall of the second cavity, the diaphragm structure is suspended in the second cavity and is spaced apart from the second peripheral wall.

As an improvement, the base includes a first substrate and a support plate provided on the first substrate, and the receiving cavity includes a first cavity formed on the first substrate and a support plate formed on the support plate. A third cavity, the peripheral wall includes a first peripheral wall that encloses the first cavity and a third peripheral wall that encloses the third cavity, and the extension arm extends from the third peripheral wall to the The suspension support part is arranged in the third cavity and spaced apart from the third peripheral wall.

As an improvement, the third peripheral wall includes an extension wall directly opposite to the movable portion and arranged at intervals, and a fixed wall provided between the extension wall and the first substrate. The fixed wall extends, and the thickness of the extension wall in a direction perpendicular to the vibration direction of the movable part is smaller than that of the fixed wall.

As an improvement, the suspension support portion is directly opposite to the fixed wall.

As an improvement, the diaphragm structure includes at least two movable parts spaced apart from each other, and the movable parts correspond to the anchoring parts one-to-one.

As an improvement, the diaphragm structure includes a first electrode sheet, a first piezoelectric diaphragm, and a second electrode sheet that are sequentially stacked along the vibration direction, and the first electrode sheet is disposed near the diaphragm structure. Said the side of the suspension support part.

As an improvement, the diaphragm structure further includes a second piezoelectric diaphragm laminated on the second electrode sheet and a third electrode sheet laminated on the second piezoelectric diaphragm.

As an improvement, the piezoelectric MEMS microphone includes several piezoelectric MEMS units, and the several piezoelectric MEMS units are spliced into the piezoelectric MEMS microphone.

As an improvement, the plurality of piezoelectric MEMS units are distributed in an array structure.

The second object of the present invention is to provide a method for manufacturing a piezoelectric MEMS microphone, including:

Providing a first substrate, and depositing a first oxide layer on the first substrate;

Depositing a diaphragm layer on the first oxide layer, and patterning the diaphragm layer to obtain a diaphragm structure, the diaphragm structure having an anchor portion and a movable portion connected to the anchor portion;

Etching forms a first cavity on the first substrate, and the remaining first substrate forms a first peripheral wall that surrounds the first cavity and a support, and the support includes a support provided in the first cavity And a suspension support portion arranged at intervals from the first peripheral wall and an extension arm extending from the first peripheral wall to the suspension support portion;

The first oxide layer is etched to suspend the movable part.

As an improvement, the preparation method further includes: depositing a diaphragm layer on the first oxide layer, and patterning the diaphragm layer to obtain the diaphragm structure, and then performing the following steps:

A second substrate is deposited on the first oxide layer, and the second substrate is patterned to form a second peripheral wall surrounding the diaphragm structure, and the diaphragm structure is spaced apart from the second peripheral wall.

The third object of the present invention is to provide a method for manufacturing a piezoelectric MEMS microphone, including:

A first silicon nitride layer is deposited on the first oxide layer, and the first silicon nitride layer is patterned. The remaining first silicon nitride layer forms a fixed wall and a supporting member, the supporting member includes A suspension support part arranged at intervals from the fixed wall and an extension arm extending from the fixed wall to the suspension support part;

A second oxide layer is deposited on the first silicon nitride layer after the patterning process, and the second oxide layer is planarized to keep the second oxide layer away from one side of the first substrate and A side surface of the suspension supporting portion away from the first substrate is flush;

A first polysilicon layer is deposited on the second oxide layer and the suspension support part, and the first polysilicon layer is patterned, and the suspension support part is far away from the first polysilicon layer. A positioning hole is formed on one side of the substrate;

Depositing a second silicon nitride layer on the positioning hole to thicken the suspension support portion, and remove the first polysilicon layer;

A third oxide layer is deposited on the peripheral side of the suspension support portion, and the third oxide layer is planarized to keep the third oxide layer away from a side surface of the first substrate and the suspension support portion One side away from the first substrate is flush;

Performing patterning treatment on both ends of the third oxide layer after the planarization treatment;

A diaphragm layer is deposited on the third oxide layer, and the diaphragm layer is patterned to obtain a diaphragm structure. The diaphragm structure has an anchor portion fixed to the suspension support portion and is connected to the anchor The moving part connected by the fixed part;

Etching the first substrate to form a first cavity, and the remaining first substrates to form a first peripheral wall surrounding the first cavity;

The first oxide layer is etched, and the second oxide layer and the third oxide layer are removed to suspend the movable part.

As an improvement, the preparation method further includes: depositing a diaphragm layer on the third oxide layer, and patterning the diaphragm layer to obtain the diaphragm structure, and then performing the following steps:

A second polysilicon layer is deposited on the first silicon nitride layer, and the second polysilicon layer is patterned. The remaining second polysilicon layer forms an epitaxial wall. The epitaxial walls are directly opposite and arranged at intervals.

The beneficial effect of the present invention is that the piezoelectric MEMS microphone of the present invention fixes the diaphragm structure part to the suspension support part provided in the receiving cavity formed by the substrate by setting the support member, and the support member of the present invention can avoid the traditional back cavity The effect of the etching process on the diaphragm structure can also improve the sensitivity of the microphone to a certain extent.

【Explanation of the drawings】

FIG. 1 is a schematic structural diagram of a piezoelectric MEMS microphone according to Embodiment 1 of the present invention;

2 is a schematic diagram of the structure of the piezoelectric MEMS unit according to Embodiment 1 of the present invention;

FIG. 3 is a schematic structural view of the piezoelectric MEMS unit of the embodiment 1 of the present invention in another direction; FIG.

Figure 4 is a view from the A-A direction of Figure 3;

Figure 5 is a perspective view from the direction A-A of Figure 3;

6 is a schematic diagram of the structure of a piezoelectric MEMS unit according to Embodiment 2 of the present invention;

Figure 7 is a B-B view of Figure 6;

Figure 8 is a B-B perspective view of Figure 10;

FIG. 9 is a schematic structural diagram of a piezoelectric MEMS unit according to Embodiment 3 of the present invention;

FIG. 10 is a top view of a piezoelectric MEMS unit according to Embodiment 3 of the present invention;

Figure 11 is a C-C view of Figure 10;

Figure 12 is a C-C perspective view of Figure 10;

FIG. 13 is a flowchart of a method for manufacturing a piezoelectric MEMS microphone according to Embodiment 2 of the present invention; FIG.

14 and 15 are a flowchart of a method for manufacturing a piezoelectric MEMS microphone according to Embodiment 3 of the present invention;

FIG. 16 is a schematic diagram of the deformation caused by the bending of the diaphragm in the prior art;

Fig. 17 is a schematic diagram of deformation caused by bending of a cantilever beam in the prior art.

Attached icon number:

1. Piezoelectric MEMS microphone;

10. Piezoelectric MEMS unit;

100. Base; 11. First substrate; 111. First cavity; 112. First peripheral wall; 12. First oxide layer; 121. Fourth cavity; 122. Fourth peripheral wall; 13. Second substrate 131, second cavity; 132, second peripheral wall; 14, support plate; 141, third cavity; 142, third peripheral wall; 143, extension wall; 144, fixed wall; 15, containing cavity; 16, peripheral wall 17. The second oxide layer; 18, the first polysilicon layer; 19, the third oxide layer; 20, the positioning hole;

200. Support; 21. Suspended support part; 22. Extension arm;

300. Diaphragm structure; 31. Anchor part; 32. Movable part; 331. First electrode sheet; 332. First piezoelectric diaphragm; 333. Second electrode sheet; 334. Second piezoelectric diaphragm; 335 , The third electrode sheet.

【Detailed ways】

The present invention will be further described below in conjunction with the drawings and embodiments.

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

It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, the element may be directly on the other element or a centering element may exist at the same time. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or an intermediate element may be present at the same time.

Example 1

Referring to Figures 1 to 5 and Figure 13, an embodiment of the present invention provides a piezoelectric MEMS microphone 1. The piezoelectric MEMS microphone 1 includes a plurality of piezoelectric MEMS units 10, and the plurality of piezoelectric MEMS units 10 are spliced into a piezoelectric MEMS microphone. 1. Moreover, several piezoelectric MEMS units 10 are distributed in an array structure. In this embodiment, there are 4 piezoelectric MEMS units 10, which are distributed in a 2*2 array structure. Of course, to ensure a certain sensitivity or signal-to-noise In contrast, the piezoelectric MEMS unit 10 can also be designed into a 3*3 array structure distribution, a 4*4 array structure distribution or more array structures.

1 to 5, the piezoelectric MEMS unit 10 includes a base 100, a support 200, and a diaphragm structure 300. The base 100 is square, the base 100 includes a first substrate 11, and the first substrate 11 includes a first cavity 111 The supporting member 200 includes a suspension supporting portion 21 arranged in the first cavity 111 and spaced apart from the first circumferential wall 112, and an extension arm extending from the first circumferential wall 112 to the suspension supporting portion 21 22. The suspension support portion 21 is provided at the center of the first cavity 111, the diaphragm structure 300 is suspended in the first cavity 111, and the diaphragm structure 300 is partially fixed to the suspension support portion 21. The diaphragm structure 300 has The anchor portion 31 fixed by the suspension support portion 21 and the movable portion 32 connected to the anchor portion 31 and suspended outside the first cavity 111.

Specifically, a side surface of the suspension support portion 21 facing the diaphragm structure 300 is flush with a side surface of the first substrate 11 facing the diaphragm structure 300. The extension arm 22 can be used to provide a certain degree of support and protection to the diaphragm structure 300 when the diaphragm structure 300 undergoes a large deformation, so as to prevent the diaphragm structure 300 from breaking.

1 to 5, the base 100 further includes a first oxide layer 12 provided on the first substrate 11, the first oxide layer 12 includes a fourth peripheral wall 122 surrounding a fourth cavity 121, the fourth cavity 121 and The first cavity 111 communicates, the first cavity 111 communicates with the fourth cavity 121 to form a receiving cavity 15, and the first peripheral wall 112 and the fourth peripheral wall 122 surround to form an annular peripheral wall 16.

In the piezoelectric MEMS microphone 1, the diaphragm structure 300 is suspended in the accommodating cavity 15 formed by the base 100 by setting the support 200, and the suspension supporting portion 21 is provided at the center of the first cavity 111, which changes the diaphragm structure 300 The anchor point position of the support member 200 reduces the deformation degree of the support member 200 during the bending process of the diaphragm structure 300, and the support member 200 can avoid the influence of the traditional back cavity etching process on the structure of the diaphragm structure 300. Increase the sensitivity of the microphone.

1 to 5 and 13, the diaphragm structure 300 includes at least two movable portions 32 spaced apart from each other, the movable portions 32 correspond to the anchor portions 31 one-to-one, and the diaphragm structure 300 includes successively stacked second portions along the vibration direction. An electrode sheet 331, a first piezoelectric film 332, a second electrode sheet 333, a second piezoelectric film 334, and a third electrode sheet 335. The material of the first electrode sheet 331 includes but is not limited to Mo, Ti/Mo, Pt, Al, W, etc., the materials of the first piezoelectric film 332 and the second piezoelectric film 334 include but are not limited to AlN, ZnO, PZT, AlScN, etc., the materials of the second electrode plate 333 and the third electrode plate 335 Including but not limited to AlN, ZnO, PZT, AlScN, etc., the second electrode sheet 333 and the third electrode sheet 335 Al, Mo, Pt, Au, TiN, etc. The first electrode sheet 331 is fixed on the suspension support portion 21. The diaphragm structure 300 is arranged in a multilayer structure so that the radius of curvature of the diaphragm structure 300 is larger. When the same bending angle is generated, the valve 33 will generate greater strain, thereby generating a greater output signal. In this embodiment, the diaphragm structure 300 includes four movable parts 32 and four anchor parts 31 corresponding to the movable parts 32 one-to-one. One movable part 32 and one anchor part 31 are integrally formed, and the whole is a fan-shaped structure. In addition, the four movable parts 32 and the four anchor parts 31 form a circular structure. It is understandable that in other embodiments, the number of movable parts 32 and anchoring parts 31 can be any required number, and the overall structure of the movable parts 32 and anchoring parts 31 can also be any shape, and at the same time, the The structure enclosed by the plurality of movable parts 32 and the anchoring part 31 may also have any shape.

This embodiment also provides a method for manufacturing the piezoelectric MEMS microphone 1, including:

A first substrate 11 is provided, a first oxide layer 12 is deposited on the first substrate 11 by LPCVD or PECVD, and the first substrate 11 is a single crystal silicon substrate;

A diaphragm layer is deposited on the first oxide layer 12, and the diaphragm layer is patterned to obtain a diaphragm structure 300. The diaphragm structure 300 has an anchor portion 31 and a movable portion 32 connected to the anchor portion 31;

The first substrate 11 is etched to form a first cavity 111, and the remaining first substrate 11 forms a first peripheral wall 112 enclosing the first cavity 111 and a supporting member 200. The supporting member 200 includes a first cavity provided in the first cavity. 111 and a suspension support portion 21 spaced apart from the first peripheral wall 112 and an extension arm 22 extending from the first peripheral wall 112 to the suspension support portion 21;

The first oxide layer 12 is etched to suspend the movable part 32.

The manufacturing method of the piezoelectric MEMS microphone 1 of this embodiment directly etches the first substrate 11 to form the support 200, which can save costs and improve production efficiency.

Example 2

Referring to FIGS. 6-8 and 13, the piezoelectric MEMS unit 10 provided by this embodiment is compared with the piezoelectric MEMS unit 10 provided by Embodiment 1: The substrate 100 of this embodiment further includes a first oxide layer 12 The second substrate 13 is provided to prevent air leakage. The second substrate 13 includes a second peripheral wall 132 enclosing a second cavity 131. The diaphragm structure 300 is suspended in the second cavity 131 and is connected to the second cavity 131. The two peripheral walls 132 are arranged at intervals, the first cavity 111, the fourth cavity 121 and the second cavity 131 communicate with each other to form the receiving cavity 15, and the first peripheral wall 112, the fourth peripheral wall 122 and the second peripheral wall 132 enclose to form an annular peripheral wall 16.

The second substrate 13 is deposited on the first oxide layer 12, and the second substrate 13 is patterned to form a second peripheral wall 132 surrounding the diaphragm structure 300. The diaphragm structure 300 and the second peripheral wall 132 are spaced apart. The second substrate 13 is a polysilicon substrate;

The first oxide layer 12 is etched to suspend the movable part 32.

Example 3

Referring to FIGS. 9-12 and 14-15, the piezoelectric MEMS unit 10 provided in this embodiment is compared with the piezoelectric MEMS unit 10 provided in Embodiment 2: The structure of the substrate 100 in this embodiment is different. The position of the support 200 has also changed. The base 100 of this embodiment includes a first substrate 11, a first oxide layer 12 provided on the first substrate 11, a support plate 14 provided on the first oxide layer 12, and the first substrate 11 includes a first peripheral wall 112 enclosing a first cavity 111, and the first oxide layer 12 includes a fourth peripheral wall 122 enclosing a fourth cavity 121. The fourth cavity 121 communicates with the first cavity 111 and supports The plate 14 includes a third peripheral wall 142 enclosing a third cavity 141. The third peripheral wall 142 includes an extension wall 143 directly opposite to the movable portion 32 and spaced apart, and a fixed wall disposed between the extension wall 143 and the first substrate 11. 144. The thickness of the extension wall 143 in the direction perpendicular to the vibration direction of the movable part 32 is smaller than that of the fixed wall 144. The extension wall 143 can prevent air leakage. The first cavity 111, the fourth cavity 121 and the third cavity 141 are connected. A receiving cavity 15 is formed. The first peripheral wall 112, the fourth peripheral wall 122 and the third peripheral wall 142 are enclosed to form an annular peripheral wall 16. The extension arm 22 extends from the fixed wall 144 to the suspension support portion 21, and the suspension support portion 21 is connected to the fixed The wall 144 is directly opposite.

A first silicon nitride layer is deposited on the first oxide layer 12, and the first silicon nitride layer is patterned. The remaining first silicon nitride layer forms a fixed wall 144 and a supporting member 200. The supporting member 200 includes and fixed The wall 144 is provided with a suspension support portion 21 and an extension arm 22 extending from the fixed wall 144 to the suspension support portion 21;

The second oxide layer 17 is deposited on the support plate 14 after the patterning process, and the second oxide layer 17 is flattened by CMP so that the second oxide layer 17 is away from the side of the first substrate 11 and the suspension support 21 One side of the first substrate 11 is flush;

The first polysilicon layer 18 is deposited on the second oxide layer 17 and the suspension support portion 21, and the first polysilicon layer 18 is patterned, on the side of the suspension support portion 21 away from the first substrate 11 Form positioning holes 20;

Depositing a second silicon nitride in the positioning hole 20 to thicken the suspension support portion 21, and removing the first polysilicon layer 18;

A third oxide layer 19 is deposited on the peripheral side of the suspension support portion 21, and a CMP planarization process is performed on the third oxide layer 19 to keep the third oxide layer 19 away from a side surface of the first substrate 11 and the suspension support portion 21 One side away from the first substrate 11 is flush;

Performing patterning treatment on both ends of the third oxide layer 19 after the CMP planarization treatment;

A diaphragm layer is deposited on the third oxide layer 19, and the diaphragm layer is patterned to obtain a diaphragm structure 300. The diaphragm structure 300 has an anchor portion 31 fixed to the suspension support portion 21 and an anchor portion 31 Connected moving part 32;

A second polysilicon layer is deposited on the first silicon nitride layer, and the second polysilicon layer is patterned. The remaining second polysilicon layer forms an epitaxial wall 143, and the movable portion 32 is directly opposite to the epitaxial wall 143 And the interval setting;

The first substrate 11 is etched to form a first cavity 111, and the remaining first substrate 11 forms a first peripheral wall 112 that encloses the first cavity 111;

The first oxide layer 12 is etched, and the second oxide layer 17 and the third oxide layer 19 are removed to suspend the movable part 32.

The above are only the embodiments of the present invention. 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 invention, but these all belong to the present invention. The scope of protection.

Claims

A piezoelectric MEMS microphone is characterized in that it includes at least one piezoelectric MEMS unit, and the piezoelectric MEMS unit includes:

The base includes an annular peripheral wall that encloses a receiving cavity;

The supporting member includes a suspension support part arranged in the receiving cavity and spaced apart from the peripheral wall, and an extension arm extending from the peripheral wall to the suspension support part;

The diaphragm structure is partially fixed to the suspension support portion, the diaphragm structure has an anchor portion fixed to the suspension support portion and a movable portion connected with the anchor portion, and the movable portion is along The axial orthographic projection of the substrate falls into the receiving cavity.
The piezoelectric MEMS microphone according to claim 1, wherein the base includes a first substrate located on a side of the movable part close to the support, and the receiving cavity includes a first substrate formed on the first substrate. A first cavity, the peripheral wall includes a first peripheral wall enclosing the first cavity, the extension arm extends from the first peripheral wall to the suspension support portion, the suspension support portion is provided It is arranged in the first cavity and spaced from the first peripheral wall.
The piezoelectric MEMS microphone according to claim 2, wherein a side surface of the suspension support portion facing the diaphragm structure is flush with a side surface of the first substrate facing the diaphragm structure. The diaphragm structure is suspended outside the first cavity.
The piezoelectric MEMS microphone according to claim 2, wherein the base further includes a second substrate stacked on the first substrate, and the receiving cavity further includes a second substrate formed on the second substrate. The cavity, the peripheral wall further includes a second peripheral wall enclosing the second cavity, and the diaphragm structure is suspended in the second cavity and is spaced apart from the second peripheral wall.
The piezoelectric MEMS microphone according to claim 1, wherein the base includes a first substrate and a support plate provided on the first substrate, and the receiving cavity includes a first substrate formed on the first substrate. A cavity and a third cavity formed on the support plate, the peripheral wall includes a first peripheral wall enclosing the first cavity and a third peripheral wall enclosing the third cavity, the extension arm Extending from the third peripheral wall to the suspension support portion, the suspension support portion is disposed in the third cavity and is spaced apart from the third peripheral wall.
The piezoelectric MEMS microphone according to claim 5, wherein the third peripheral wall comprises an epitaxial wall directly opposite to the movable part and arranged at intervals, and an epitaxial wall arranged between the epitaxial wall and the first substrate The extension arm extends from the fixed wall, and the thickness of the extension wall in a direction perpendicular to the vibration direction of the movable part is smaller than that of the fixed wall.
The piezoelectric MEMS microphone according to claim 6, wherein the suspension support portion is directly opposite to the fixed wall.
The piezoelectric MEMS microphone according to claim 1, wherein the diaphragm structure comprises at least two movable parts spaced apart from each other, and the movable parts correspond to the anchoring parts one-to-one.
8. The piezoelectric MEMS microphone according to claim 8, wherein the diaphragm structure includes a first electrode sheet, a first piezoelectric diaphragm and a second electrode sheet stacked in sequence along the vibration direction, and the first electrode The sheet is arranged on a side of the diaphragm structure close to the suspension support portion.
The piezoelectric MEMS microphone according to claim 9, wherein the diaphragm structure further comprises a second piezoelectric diaphragm stacked on the second electrode plate and a second piezoelectric diaphragm stacked on the second piezoelectric film. The third electrode on the chip.
The piezoelectric MEMS microphone according to any one of claims 1-10, wherein the piezoelectric MEMS microphone comprises a plurality of the piezoelectric MEMS microphones, and the plurality of piezoelectric MEMS units are spliced into the piezoelectric MEMS microphone.
The piezoelectric MEMS microphone according to claim 11, wherein the plurality of piezoelectric MEMS units are distributed in an array structure.
A method for manufacturing a piezoelectric MEMS microphone is characterized in that it comprises:

Providing a first substrate, and depositing a first oxide layer on the first substrate;

Depositing a diaphragm layer on the first oxide layer, and patterning the diaphragm layer to obtain a diaphragm structure, the diaphragm structure having an anchor portion and a movable portion connected to the anchor portion;

Etching forms a first cavity on the first substrate, and the remaining first substrate forms a first peripheral wall that surrounds the first cavity and a support, and the support includes a support provided in the first cavity And a suspension support portion arranged at intervals from the first peripheral wall and an extension arm extending from the first peripheral wall to the suspension support portion;

The first oxide layer is etched to suspend the movable part.
The preparation method according to claim 13, wherein the preparation method further comprises: depositing a diaphragm layer on the first oxide layer, and patterning the diaphragm layer to obtain a diaphragm structure, and then performing the following Process:

A second substrate is deposited on the first oxide layer, and the second substrate is patterned to form a second peripheral wall surrounding the diaphragm structure, and the diaphragm structure is spaced apart from the second peripheral wall.
A method for manufacturing a piezoelectric MEMS microphone is characterized in that it comprises:

Providing a first substrate, and depositing a first oxide layer on the first substrate;

A first silicon nitride layer is deposited on the first oxide layer, and the first silicon nitride layer is patterned. The remaining first silicon nitride layer forms a fixed wall and a supporting member, the supporting member includes A suspension support part arranged at intervals from the fixed wall and an extension arm extending from the fixed wall to the suspension support part;

A second oxide layer is deposited on the first silicon nitride layer after the patterning process, and the second oxide layer is planarized to keep the second oxide layer away from one side of the first substrate and A side surface of the suspension supporting portion away from the first substrate is flush;

A first polysilicon layer is deposited on the second oxide layer and the suspension support part, and the first polysilicon layer is patterned, and the suspension support part is far away from the first polysilicon layer. A positioning hole is formed on one side of the substrate;

Depositing a second silicon nitride layer on the positioning hole to thicken the suspension support portion, and remove the first polysilicon layer;

A third oxide layer is deposited on the peripheral side of the suspension support portion, and the third oxide layer is planarized to keep the third oxide layer away from a side surface of the first substrate and the suspension support portion One side away from the first substrate is flush;

Performing patterning treatment on both ends of the third oxide layer after the planarization treatment;

A diaphragm layer is deposited on the third oxide layer, and the diaphragm layer is patterned to obtain a diaphragm structure. The diaphragm structure has an anchor portion fixed to the suspension support portion and is connected to the anchor The moving part connected by the fixed part;

Etching the first substrate to form a first cavity, and the remaining first substrates to form a first peripheral wall surrounding the first cavity;

The first oxide layer is etched, and the second oxide layer and the third oxide layer are removed to suspend the movable part.
The preparation method according to claim 15, wherein the preparation method further comprises: depositing a diaphragm layer on the third oxide layer, and patterning the diaphragm layer to obtain the diaphragm structure, and then performing the following Process:

A second polysilicon layer is deposited on the first silicon nitride layer, and the second polysilicon layer is patterned. The remaining second polysilicon layer forms an epitaxial wall. The epitaxial walls are directly opposite and arranged at intervals.