A MEMS element and an electro-acoustic transducer

Abstract

The application provides a MEMS element and an electroacoustic conversion device, and relates to the technical field of microphones. The MEMS element comprises a spacer, a counter electrode, a first diaphragm and a second diaphragm. The spacer and the counter electrode are located on the same horizontal plane and are alternately arranged on the cross section of the MEMS element. The first diaphragm and the second diaphragm are respectively arranged on the opposite sides of the spacer and are in airtight connection. The first diaphragm comprises a plurality of first protrusions which are arranged at intervals along a first direction, and the second diaphragm comprises a plurality of second protrusions which are arranged at intervals along the first direction. The first protrusions and the second protrusions correspond to each other and are aligned to form a cavity, and the counter electrode is suspended in the cavity. The first protrusions comprise a first front wall and a first back wall, the second protrusions comprise a second front wall and a second back wall, and at least part of the first front wall, the first back wall, the second front wall or the second back wall is a sub-corrugated structure. The MEMS element can reduce the maximum stress applied to the diaphragm under high pressure impact, thereby improving the mechanical robustness of the device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electro-acoustic conversion devices, in particular to a MEMS element and an electro-acoustic conversion device. BACKGROUND

[0002] In the field of micro-electro-mechanical system (MEMS) microphones, certain structures can be designed with a sealed cavity surrounded by two corrugated diaphragms, wherein the sealed cavity presents a reduced air pressure, provided with a backplate acting as a counter electrode, to form a differential capacitive sensing system.

[0003] When the double diaphragm structure is subjected to high pressure (from a drop or air impact - about 1 MPa), the diaphragms will be subjected to high displacement upwards or downwards accordingly (about tens of microns). At such a high displacement, high stress will occur in the local part of the diaphragm, and cracks can be generated in the material, thereby causing damage to the structure, eventually leading to the damage of the microphone.

[0004] Therefore, it is desirable to provide an improved micro-electro-mechanical system element which at least overcomes one of the above problems. SUMMARY

[0005] To solve the above technical problems, an embodiment of the present application provides a MEMS element, comprising:

[0006] a plurality of spacers arranged along a first direction,

[0007] a plurality of counter electrodes arranged along the first direction,

[0008] a plurality of slots, each of which is formed between adjacent counter electrodes and spacers;

[0009] a first diaphragm comprising a plurality of first protrusions arranged along the first direction at intervals;

[0010] a second diaphragm comprising a plurality of second protrusions arranged along the first direction at intervals, the second protrusions extending away from the first protrusions;

[0011] the plurality of spacers and the plurality of counter electrodes are located on the same horizontal plane and are arranged alternately in a cross section of the MEMS element;

[0012] the first diaphragm and the second diaphragm are respectively arranged on opposite sides of the spacers and are airtightly connected;

[0013] the plurality of first protrusions correspond one-to-one to the plurality of second protrusions, and corresponding first protrusions and second protrusions are aligned with each other to form cavities, and the counter electrodes are suspended in the cavities;

[0014] The portion between two adjacent first protrusions is a first portion, the portion between two adjacent second protrusions is a second portion, the corresponding first portion and second portion are aligned, and the spacer is clamped between the first portion and the second portion;

[0015] The first protrusion comprises a first front wall and a first back wall oppositely arranged along the first direction, and the second protrusion comprises a second front wall and a second back wall oppositely arranged along the first direction;

[0016] At least part of the first front wall, the first back wall, the second front wall and the second back wall is a sub-wavy structure.

[0017] In some embodiments, the first front wall and the first back wall adjacent to the first portion of the spacer connected to the edge of the first diaphragm are sub-wavy structures, and the second front wall and the second back wall adjacent to the second portion of the spacer connected to the edge of the second diaphragm are sub-wavy structures.

[0018] In some embodiments, the first front wall and the first back wall adjacent to the first portion of the spacer connected to the outermost circle or the next outermost circle of the first diaphragm are sub-wavy structures, and the second front wall and the second back wall adjacent to the second portion of the spacer connected to the outermost circle or the next outermost circle of the second diaphragm are sub-wavy structures.

[0019] In some embodiments, the first front wall and the first back wall adjacent to the first portion of the spacer connected to the outermost two or three circles of the first diaphragm are sub-wavy structures, and the second front wall and the second back wall adjacent to the second portion of the spacer connected to the outermost two or three circles of the second diaphragm are sub-wavy structures.

[0020] In some embodiments, the first front wall and the first back wall adjacent to the first portion of the spacer connected to all the spacers of the first diaphragm are sub-wavy structures, and the second front wall and the second back wall adjacent to the second portion of the spacer connected to all the spacers of the second diaphragm are sub-wavy structures.

[0021] In some embodiments, the sub-wavy structure comprises a third peak and a third valley connected to each other along the first direction, the third peak is connected to the first portion and the second portion respectively, and the third valley is connected to the top of the first protrusion and the second protrusion respectively.

[0022] In some embodiments, the top of the third peak and the bottom of the third valley are conical or flat.

[0023] In some embodiments, the top of the third peak is lower than or flush with the top of the first protrusion and the second protrusion.

[0024] In some embodiments, the bottom of the third valley is higher than or flush with the height of the first portion and the second portion.

[0025] In some embodiments, the length of the sub-wavy structure in the first direction is less than the length of the first protrusion, the second protrusion, the first portion, or the second portion.

[0026] In some embodiments, the sub-wavy structure is integrally formed with the first diaphragm or the second diaphragm.

[0027] In some embodiments, the first protrusion and the second protrusion have the same shape and size, and the first portion and the second portion have the same length.

[0028] In some embodiments, the top of the first protrusion and the second protrusion is flat, and the first portion and the second portion are flat.

[0029] In some embodiments, the cavity is sealed, and the internal pressure is less than the external atmospheric pressure.

[0030] In some embodiments, the cavity is in a vacuum state.

[0031] In some embodiments, the first direction is radial or transverse.

[0032] In some embodiments, the first diaphragm and the second diaphragm are made of conductive material, or include an insulating film with conductive elements.

[0033] In some embodiments, the first diaphragm and the second diaphragm each further include a plurality of radial spokes, which divide the first diaphragm and the second diaphragm into several parts in the circumferential direction.

[0034] In some embodiments, at least part of the counter electrode is suspended between the sub-wavy structure of the first diaphragm and the sub-wavy structure of the second diaphragm corresponding thereto, and the two opposite surfaces of the counter electrode are not in contact with the sub-wavy structure of the first diaphragm and the second diaphragm, respectively.

[0035] Compared with the prior art, the present application has the following beneficial effects:

[0036] By setting at least part of the first front wall, the first back wall, the second front wall, or the second back wall as a sub-wavy structure, since the sub-wavy structure has an additional bending degree of freedom, it allows it to have a different deformation from the double-diaphragm structure and release stress through the deformation, so it can share the stress at the corner where the first protrusion or the second protrusion is connected to the respective diaphragm, thereby ultimately reducing the maximum stress of the diaphragm; at the same time, the MEMS element can also maintain the original stiffness of the first diaphragm and the second diaphragm, so that the original performance is maintained, thereby greatly improving the robustness of the device, effectively reducing the maximum stress applied to the diaphragm under high pressure impact (falling, air impact), and ultimately improving the mechanical robustness of the device.

[0037] In addition, the micro-electro-mechanical system element of the present application has high acoustic compliance and sensitivity.

[0038] To solve the above technical problems, the present application also provides an electro-acoustic conversion device, comprising the MEMS element as described above, and a circuit electrically connected with the MEMS element.

[0039] The electro-acoustic conversion device has the same advantages as the MEMS element described above, and will not be described here again. BRIEF DESCRIPTION OF DRAWINGS

[0040] One or more embodiments are illustrated by way of example in the figures that form a part of this patent document. These example embodiments demonstrate, but do not limit, the scope of the embodiments. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like elements. Drawings illustrating the figures are not necessarily to scale and the emphasis is placed upon the illustrative nature of the embodiments.

[0041] Figure 1 A top view of the MEMS element with radial corrugations in some embodiments of the present application;

[0042] Figure 2 A partial cross-sectional view of the MEMS element in an embodiment of the present application; Figure 1

[0043] Figure 3 A partial cross-sectional view of the MEMS element with sub-corrugations in some embodiments of the present application;

[0044] Figure 4 A partial cross-sectional view of the MEMS element with sub-corrugations in some other embodiments of the present application.

[0045] The reference signs are explained as follows. Here, the reference signs should not be understood as limiting the claims.

[0046] 11, spacer; 12, counter electrode; 13, slot; 2, first diaphragm; 21, first protrusion; 22, first portion; 211, first front wall; 212, first back wall; 4, spider; 3, second diaphragm; 31, second protrusion; 32, second portion; 311, second front wall; 312, second back wall; 41, cavity; 5, corrugated structure; 51, third peak; 52, third valley. DETAILED DESCRIPTION

[0047] ​The present application will be further described with reference to the drawings. It is to be noted that like elements or components in the various figures are denoted by the same reference numerals. The embodiments described herein are not meant to be an exhaustive description of various other embodiments of the application. Also, the embodiments described herein are not meant to be exhaustive descriptions of all aspects or alternatives of the embodiments described herein. Furthermore, the illustrated embodiments are not necessarily meant to have all aspects or advantages shown. In the description of the application, it is to be understood that the terms "first", "second", "third", etc. are used merely as labels, and are not intended to impose numerical or relative priorities such that a feature described as the "first" element is necessarily, or is intended to be, the most important element or step, or is necessarily, or is intended to be, the chronological first element or step. Unless otherwise indicated, the meaning of "a", "an", and "the" includes plural references.

[0048] The terminology used in the various embodiments described herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "comprises", "comprising", "includes", "including", "has", "having", "has" and "having" when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0049] Referring to Figures 1 to 4 In accordance with the present application, a MEMS element is provided. The MEMS element includes a plurality of spacers 11, a plurality of counter electrodes 12, a first diaphragm 2 and a second diaphragm 3. The plurality of spacers 11 and the plurality of counter electrodes 12 are arranged along a first direction, lie in the same horizontal plane, and are alternately arranged in a cross-section of the MEMS element. A gap is left between adjacent counter electrodes 12 and spacers 11 to form a slot 13. The first diaphragm 2 and the second diaphragm 3 have similar corrugated structures, each including a plurality of protrusions arranged along the first direction, and the protrusions of each diaphragm extend in opposite directions in a second direction. In addition, the first diaphragm 2 is arranged opposite to the second diaphragm 3 and is hermetically connected to the second diaphragm 3. The first direction is referred to as the radial or lateral direction, and the second direction is referred to as the vertical direction.

[0050] For the sake of convenience, the protrusions of the first diaphragm 2 are referred to as first protrusions 21, and the protrusions of the second diaphragm 3 are referred to as second protrusions 31. The first protrusions 21 and the second protrusions 31 can have the same shape and size. The shape of the first protrusions 21 and the second protrusions 31 can be rectangular, trapezoidal, or triangular, or the like, in a surface perpendicular to the first diaphragm 2 and the second diaphragm 3 (i.e., a surface in the second direction).

[0051] The portion of the first diaphragm 2 between two adjacent first protrusions 21 is referred to as a first portion 22 (i.e., the portion of the first diaphragm 2 other than the first protrusions 21), and the portion of the second diaphragm 3 between two adjacent second protrusions 31 is referred to as a second portion 32 (i.e., the portion of the second diaphragm 3 other than the second protrusions 31). The first portion 22 and the second portion 32 can have the same shape and size, and can be flat, for example. Thus, the first portion 22 and the second portion 32 can have the same length.

[0052] The first protrusions 21 and the second protrusions 31 are aligned with each other to form a cavity 41, and the counter electrode 12 is suspended in the cavity 41. The first portion 22 and the second portion 32 are aligned with each other, and are connected by the spacer 11. In other words, one end of the spacer 11 is connected to the first portion 22, and the other end of the spacer 11 is connected to the second portion 32, i.e., the spacer 11 is sandwiched between the first portion 22 and the second portion 32.

[0053] The spacer 11 can be a pillar or the like. The spacer 11 can be integrally formed with the first diaphragm 2 or the second diaphragm 3. Alternatively, the spacer 11 can be formed between the first diaphragm 2 and the second diaphragm 3 after they are assembled together.

[0054] Note that the first diaphragm 2 and the second diaphragm 3 are corrugated conductive diaphragms, and have the same shape and size, and are typically circular. In some embodiments, the first diaphragm 2 and the second diaphragm 3 are divided into six portions in the circumferential direction, and adjacent portions are connected to each other by a spoke 4 extending in the radial direction of the diaphragm (i.e., the first direction). That is, the first diaphragm and the second diaphragm can further include a plurality of spokes 4. In other embodiments, the first diaphragm 2 and the second diaphragm 3 can have other shapes, such as a square, a hexagon, an octagon, or the like, without limitation.

[0055] In some embodiments, the first corrugated conductive diaphragm 2 and the second corrugated conductive diaphragm 3 can be made of a conductive material or include an insulating film on which a conductive element is provided. For example, the first corrugated conductive diaphragm 2 and the second corrugated conductive diaphragm 3 include a silicon nitride film, and a polysilicon electrode is formed on the surface of the diaphragm facing the counter electrode 12 to provide conductivity.

[0056] As Figures 2 to 4As shown, the first corrugated conductive membrane 2 includes a plurality of first protrusions 21 and a plurality of first portions arranged alternately along the first direction, and the second corrugated conductive membrane 3 includes a plurality of second protrusions 31 and a plurality of second portions arranged alternately along the first direction. The second protrusions 31 extend in a direction away from the first protrusions 21, while the second portions 32 extend in a direction toward the first portions 21. Since the first protrusions 21 and the second protrusions 31 have the same shape and size, and the first portions 22 and the second portions 32 also have the same shape and size, the first corrugated conductive membrane 2 and the second corrugated conductive membrane 3 have the same length.

[0057] It should be noted that the top of the first protrusions 21 and the second protrusions 32, for example, but not limited to, is flat, as shown. Figures 2 to 4 In other embodiments, the top of the first protrusions 21 and the second protrusions 32 can also be V-shaped, circular-arched or arc-shaped protrusions, which are not limited here.

[0058] The protrusions of the first membrane 2 and the second membrane 3 respectively include a front wall and a back wall arranged oppositely along the first direction. For the convenience of description, the front wall and the back wall of the first protrusions 21 can be referred to as the first front wall 211 and the first back wall 212, and the front wall and the back wall of the second protrusions 31 can be referred to as the second front wall 311 and the second back wall 312.

[0059] The inclination angles of the first front wall 211, the first back wall 212, the second front wall 311 and the second back wall 312 can be greater than 0°, but less than or equal to 90°.

[0060] Since the corner where the membrane is connected with the front wall and the back wall will have local high stress when the membrane is subjected to high pressure, which will cause damage to the structure. Therefore, in some embodiments, at least part of the front wall or the back wall is arranged as a sub-corrugated structure 5. Specifically, as shown in Figure 3 and Figure 4 At least part of the first front wall 211, the first back wall 212, the second front wall 311 or the second back wall 312 is a sub-corrugated structure 5.

[0061] When the membrane is subjected to high pressure, the sub-corrugated structure 5 can effectively reduce the local stress by its own buffering, thereby effectively reducing the maximum stress applied to the membrane under high pressure impact (falling, air impact), and ultimately improving the mechanical robustness of the device.

[0062] When a MEMS element is subjected to high pressure (e.g., from a drop or air impact, up to 1 MPa), the raised slopes corresponding to the outermost and second outermost spacers 11 experience the greatest local stress impact. Therefore, preferably, the front and rear walls adjacent to the first and second portions of the spacers 11 connected to the outermost or second outermost ring of the first and second diaphragms are configured as a sub-corrugated structure 5. In this case, the MEMS element can effectively reduce local stress while better maintaining its original characteristics.

[0063] In some embodiments, the front and rear walls adjacent to the first and second portions of the spacers 11 connected to the outermost two or three rings of the first and second diaphragms may be configured as sub-corrugated structures. In some embodiments, the front and rear walls adjacent to the first and second portions of all spacers connected to the first and second diaphragms may be configured as sub-corrugated structures.

[0064] like Figure 3 and Figure 4 As shown, to maintain the consistency of the diaphragm's radial or lateral extension, in some embodiments, the sub-corrugated structures 5 are also arranged along the first direction. However, in other embodiments, the corrugated structures 5 may also be arranged at an angle (e.g., 0° to 30°) to the first direction, for example, along... Figure 2 The original extension direction of the anterior or posterior wall is not restricted here.

[0065] The sub-corrugated structure 5 includes a third peak 51 and a third valley 52 interconnected along a first direction. The third peak 51 extends away from the first and second membranes, respectively, and the third valley 52 extends towards the first and second membranes, respectively. Specifically, the third peak 51 is connected to the first portion 22 and the second portion 32, and the third valley 52 is connected to the tops of the first protrusion 21 and the second protrusion 31. Here, the connection means that each end of the first portion 22 and the second portion 32 is connected to a third peak 51, and the third valley 52 is connected to the tops of the first protrusion 21 and the second protrusion 31, respectively.

[0066] The height of the third peak 51 is less than or equal to the height of the first protrusion 21 and the second protrusion 31. In some embodiments, the height of the third peak 51 is the same as the height of the first protrusion 21 and the second protrusion 31. The height referred to herein is the highest point.

[0067] The bottom of the third valley 52 is not lower than the height of the first portion 22 and the second portion 32. In some embodiments, the bottom of the third valley 52 is on the same plane as the first portion 22 and the second portion 32.

[0068] In some embodiments, the top of the third peak 51 and the bottom of the third valley 52 may be conical or flat.

[0069] In some embodiments, the length of the sub-corrugated structure 5 in the first direction is less than the length of the first protrusion 21, the second protrusion 31, the first portion 22, or the second portion 32. For example, including, but not limited to, the length of the sub-corrugated structure 5 in the first direction may be 1 / 2, 1 / 3, 1 / 4, 2 / 3, 3 / 4, 2 / 5, 4 / 5, etc., of the length of the first protrusion 21, the second protrusion 31, the first portion 22, or the second portion 32.

[0070] In some embodiments, the sub-corrugated structure 5 may be integrally formed with the first diaphragm 2 and / or the second diaphragm 3.

[0071] like Figure 4 As shown, there is usually a gap between the sub-corrugated structure 5 at the first front wall 211 of the first protrusion 21 and the sub-corrugated structure 5 at the second front wall 311 of the second protrusion 31. The counter electrode 12 can also be suspended in the gap. That is, at least a part of the counter electrode 12 is disposed between the sub-corrugated structure 5 of the first diaphragm 2 and the sub-corrugated structure 5 of the second diaphragm 3 opposite to it, and the two opposite surfaces of the counter electrode 12 do not contact the sub-corrugated structures 5 of the first diaphragm 2 and the second diaphragm 3.

[0072] Because the sub-corrugated structure 5 has additional bending degrees of freedom, it allows for different deformations compared to the dual-diaphragm structure, and stress is released through these deformations. Therefore, it can share the stress at the corners where the first protrusion 21 or the second protrusion 31 connects to their respective diaphragms, thereby ultimately reducing the maximum stress on the diaphragms. Simultaneously, the MEMS element can maintain its original stiffness and performance.

[0073] Another embodiment of the present invention provides an electroacoustic conversion device, including the above-described MEMS element and a circuit electrically connected to the MEMS element. The electroacoustic conversion device may be an MMEMS microphone or a speaker. Although the present invention has been described with reference to one or more embodiments, the above description of the embodiments is only intended to enable those skilled in the art to practice or use the present invention. Those skilled in the art should understand that various modifications can be made without departing from the spirit or scope of the invention. The embodiments described above should not be construed as limiting the present invention, and the scope of the invention should be determined by referring to the appended claims.

Claims

1. A microelectromechanical system, MEMS, element, characterized by The application relates to a MEMS element, comprising: a plurality of spacers arranged along a first direction, a plurality of counter electrodes arranged along the first direction, a plurality of slots, each slot being formed between adjacent counter electrodes and spacers; a first diaphragm comprising a plurality of first protrusions arranged along the first direction; a second diaphragm comprising a plurality of second protrusions arranged along the first direction, the second protrusions extending away from the first protrusions; the plurality of spacers and the plurality of counter electrodes are located in the same horizontal plane and are alternately arranged in a cross section of the MEMS element; the first diaphragm and the second diaphragm are arranged on opposite sides of the spacers and are hermetically connected; the plurality of first protrusions correspond to the plurality of second protrusions one by one, and corresponding first protrusions and second protrusions are aligned with each other to form cavities, the counter electrodes are suspended in the cavities; a portion between two adjacent first protrusions is a first portion, a portion between two adjacent second protrusions is a second portion, and corresponding first portions and second portions are aligned, the spacers being arranged between the first portions and the second portions; the first protrusions comprise first front walls and first back walls arranged oppositely along the first direction, and the second protrusions comprise second front walls and second back walls arranged oppositely along the first direction; the first diaphragm and the second diaphragm are circular and have the same shape and size, and each comprise a plurality of radial spokes, the radial spokes dividing the first diaphragm and the second diaphragm into a plurality of portions in a circumferential direction; the first direction is a radial direction or a transverse direction; the first front walls and the first back walls adjacent to the first portions of all the spacers connected to the first diaphragm are sub-wavy structures, and the second front walls and the second back walls adjacent to the second portions of all the spacers connected to the second diaphragm are sub-wavy structures.

2. The MEMS element according to claim 1, characterized in that the sub-wavy structures comprise third peaks and third valleys connected to each other along the first direction, the third peaks being connected to the first portions and the second portions, and the third valleys being connected to the top of the first protrusions and the second protrusions.

3. The MEMS element according to claim 2, characterized in that the top of the third peak and the bottom of the third valley are conical or flat.

4. The MEMS element according to claim 3, characterized in that the top of the third peak is lower than or flush with the top of the first protrusions and the second protrusions.

5. The MEMS element according to claim 3, characterized in that the bottom of the third valley is higher than or flush with the height of the first portions and the second portions.

6. The MEMS element of claim 1, wherein, the length of the sub-wavy structure in the first direction is smaller than the length of the first protrusions, the second protrusions, the first portions or the second portions.

7. The MEMS element of claim 1, wherein, the sub-wavy structure is integrally formed with the first diaphragm or the second diaphragm.

8. The MEMS element of claim 1, wherein, the shape and size of the first protrusions are the same as those of the second protrusions, and the length of the first portions is the same as that of the second portions.

9. The MEMS element of claim 1, wherein, the top of the first protrusions and the second protrusions is flat, and the first portions and the second portions are flat.

10. The MEMS element of claim 1, wherein, the cavities are sealed, and the pressure inside the cavities is smaller than the external atmospheric pressure.

11. The MEMS element of claim 1, wherein, the cavities are in a vacuum state.

12. The MEMS element of claim 1, wherein, the first diaphragm and the second diaphragm are made of conductive materials, or comprise an insulating film on which conductive elements are arranged.

13. The MEMS element of claim 1, wherein, At least a part of the counter electrode is suspended between the subcorrugated structure of the first diaphragm and the subcorrugated structure of the second diaphragm corresponding thereto, and two opposite surfaces of the counter electrode are not in contact with the subcorrugated structures of the first diaphragm and the second diaphragm, respectively.

14. An electro-acoustic transducer device, characterized by A MEMS element as claimed in any one of claims 1 to 13, and an electric circuit electrically connected to the MEMS element.

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