MEMS microphone and electronic device

Abstract

The invention discloses an MEMS microphone and an electronic device. The MEMS microphone comprises a substrate structure, a diaphragm structure, a support structure and a back electrode structure. The vibrating diaphragm structure is stacked on one side of the substrate structure, the vibrating diaphragm structure comprises a first functional area located in the center and a plurality of second functional areas connected to the peripheral side of the first functional area and arranged in pairs, and each pair of second functional areas are located on the two opposite sides of the first functional area respectively; the supporting structure is stacked on one side of the substrate structure and surrounds the outer side of the vibrating diaphragm structure, and the supporting structure comprises a supporting part and a plurality of functional parts corresponding to the plurality of second functional areas; the back electrode structure is stacked on the side, away from the substrate structure, of the supporting structure and can form a parallel plate capacitor with the first functional area, and when the voltage between the vibrating diaphragm structure and the back electrode structure is larger than a set value, the first functional area can be attracted to the back electrode structure, so that the second functional area can form an interdigital capacitor with the corresponding functional part.

Description

Technical Field

[0001] This application relates to the technical field of acoustic devices, and more particularly, to a MEMS microphone and an electronic device. Background Art

[0002] A MEMS directional microphone is a microphone manufactured using microelectromechanical system (MEMS) technology. It can adjust its sensitivity according to the direction of the sound source, thereby improving the effects of speech recognition and noise reduction. However, such a directional microphone can only acquire sound signals in a specified direction. When it is necessary to collect sound signals in all directions or collect ambient noise instead of collecting sound signals in the specified direction, it is often necessary to additionally place an omnidirectional microphone, resulting in increased costs. Summary of the Invention

[0003] An object of this application is to provide a new technical solution for a MEMS microphone and an electronic device.

[0004] According to a first aspect of this application, there is provided a MEMS microphone, comprising:

[0005] A substrate structure, with a first through hole provided at the center of the substrate structure;

[0006] A diaphragm structure, which is stacked on one side of the substrate structure and is opposite to the first through hole. The diaphragm structure includes a first functional area at the center and a plurality of second functional areas arranged in pairs and connected to the periphery of the first functional area. Each pair of the second functional areas is located on opposite sides of the first functional area;

[0007] A support structure, which is stacked on one side of the substrate structure and surrounds the outside of the diaphragm structure. The support structure includes a support portion and a plurality of functional portions corresponding to the plurality of second functional areas;

[0008] A back electrode structure, which is stacked on the side of the support structure away from the substrate structure and can form a parallel plate capacitor with the first functional area. When the voltage between the diaphragm structure and the back electrode structure is greater than or equal to a set value, the first functional area can be attracted to the back electrode structure, enabling the second functional area to form an interdigital capacitor with the corresponding functional portion.

[0009] Optionally, the second functional area includes a connecting portion and a first interdigital portion, and the functional portion is a second interdigital portion;

[0010] When the voltage between the diaphragm structure and the back electrode structure is greater than the set value, the first interdigital portion and the second interdigital portion are inserted into each other to form the interdigital capacitor.

[0011] Optionally, the connecting portion is provided with a plurality of second through holes, and the plurality of second through holes are arranged in an array.

[0012] Optionally, the thickness of the second finger portion is less than the thickness of the connecting portion, and there is a gap between the second finger portion and the substrate structure.

[0013] Optionally, the diaphragm structure further includes a plurality of corrugated film portions, and each of the connecting portions is elastically connected to the periphery of the first functional region through one of the corrugated film portions.

[0014] Optionally, the corrugated film portion has a plurality of grooves arranged in parallel, so that the connecting portion and the first functional region form an elastic connection.

[0015] Optionally, a plurality of limiting posts are provided on the substrate structure, and the diaphragm structure is stacked on the substrate structure through the plurality of limiting posts;

[0016] When the voltage between the diaphragm structure and the back electrode structure is greater than a set value, the limiting posts can enable the second functional region and the corresponding functional portion to form the interdigital capacitor.

[0017] Optionally, a plurality of third through holes are provided at a position on the back electrode structure opposite to the first functional region;

[0018] The back electrode structure is provided with fourth through holes at positions opposite to each of the second functional regions, and the size of each fourth through hole completely covers the corresponding second functional region.

[0019] Optionally, there are four second functional regions, and the four second functional regions are respectively a first side portion, a second side portion, a third side portion and a fourth side portion;

[0020] Wherein, the first side portion and the third side portion are connected to opposite sides of the first functional region along a first direction, the second side portion and the fourth side portion are connected to opposite sides of the first functional region along a second direction, and the first direction is perpendicular to the second direction.

[0021] According to a second aspect of the present application, there is provided an electronic device, including: the MEMS microphone according to the first aspect.

[0022] By providing a diaphragm structure, a support structure and a back electrode structure, the MEMS microphone of the present application can control the use of a parallel plate capacitor to collect sound signals in all directions or use an interdigital capacitor to collect sound signals in a specified direction by adjusting the voltage between the back electrode structure and the diaphragm structure, thereby realizing the switching between the directional mode and the omnidirectional mode of the microphone, so that when applied, there is no need to provide an additional microphone, reducing the device cost.

[0023] Other features and advantages of the present application will become clear from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. Description of the Drawings

[0024] The drawings incorporated in and forming a part of the specification illustrate embodiments of the present application and, together with the description, are used to explain the principles of the present application.

[0025] Figure 1 It is a schematic cross-sectional view of the non-directional mode of a MEMS microphone provided by the present application.

[0026] Figure 2 It is a schematic cross-sectional view of the directional mode of a MEMS microphone provided by the present application.

[0027] Figure 3 It is a schematic top view of a back electrode structure provided by the present application.

[0028] Figure 4 It is one of the schematic top views of a diaphragm structure provided by the present application.

[0029] Figure 5 It is another schematic top view of a diaphragm structure provided by the present application.

[0030] Figure 6 It is yet another schematic top view of a diaphragm structure provided by the present application.

[0031] Figure 7 It is a schematic top view of a support structure provided by the present application.

[0032] Figure 8 It is a schematic top view of a substrate structure provided by the present application.

[0033] Figure 9 It is a schematic structural view of a corrugated film portion provided by the present application.

[0034] Figure 10 It is an analysis diagram of the working principle of the MEMS microphone provided by the present application.

[0035] Description of the Reference Numerals:

[0036] 1. Substrate structure; 11. First through hole; 12. Limit post; 2. Diaphragm structure; 21. First functional area; 22. Second functional area; 221. Connection part; 222. First interdigital part; 223. Second through hole; 2201. First side; 2202. Second side; 2203. Third side; 2204. Fourth side; 23. Corrugated film portion; 231. Groove; 3. Support structure; 31. Support part; 32. Second interdigital part; 4. Back electrode structure; 41. Third through hole; 42. Fourth through hole. Detailed Implementation Modes

[0037] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application.

[0038] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way a limitation on the present application or its application or use.

[0039] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the specification.

[0040] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0041] It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, further discussion thereof is not required in subsequent drawings.

[0042] As Figures 1 to 10 shown, according to a first aspect of the present application, there is provided a MEMS microphone, comprising: a substrate structure 1, a diaphragm structure 2, a support structure 3, and a back electrode structure 4; a first through hole 11 is provided at the center of the substrate structure 1; the diaphragm structure 2 is stacked on one side of the substrate structure 1 and is opposite to the first through hole 11, the diaphragm structure 2 includes a first functional area 21 at the center and a plurality of second functional areas 22 arranged in pairs and connected to the periphery of the first functional area 21, and each pair of second functional areas 22 are respectively located on opposite sides of the first functional area 21; the support structure 3 is stacked on one side of the substrate structure 1 and surrounds the outside of the diaphragm structure 2, the support structure 3 includes a support portion 31 and a plurality of functional portions corresponding to the plurality of second functional areas 22; the back electrode structure 4 is stacked on the side of the support structure 3 away from the substrate structure 1 and can form a parallel plate capacitor with the first functional area 21, and when the voltage between the diaphragm structure 2 and the back electrode structure 4 is greater than or equal to a set value, the first functional area 21 can be attracted to the back electrode structure 4, so that the second functional areas 22 can form interdigital capacitors with the corresponding functional portions.

[0043] Specifically, the MEMS microphone provided by the present application can simultaneously implement the functions of a directional microphone and an omnidirectional microphone. Among them, the substrate is arranged at the bottom layer and is used to support the entire microphone structure. The first through hole 11 provided in the center thereof can form a back hole with the diaphragm structure 2 to improve the sound collection effect of the microphone. The diaphragm structure 2 can vibrate under the action of a sound signal, and then convert the received sound signal into an electrical signal, so as to facilitate the storage or transmission of the sound signal, etc. The diaphragm structure 2 is stacked on the substrate structure 1, and the back electrode structure 4 is stacked on the substrate structure 1 through the support structure 3, and there is a gap between the diaphragm structure 2 and the back electrode structure 4, so that when the voltage between the back electrode structure 4 and the diaphragm structure 2 is below a set value, a parallel plate capacitor can be formed between the two, so as to realize the function of collecting sound signals or ambient noise in all directions in the omnidirectional mode of the MEMS microphone.

[0044] Further, when the voltage between the diaphragm structure 2 and the back electrode structure 4 is greater than or equal to the set value, the first functional area 21 on the back electrode structure 4 and the diaphragm structure 2 are attracted to each other under the action of static electricity, so that a plurality of second functional areas 22 are all in a suspended state. Then, a finger capacitor is formed between the second functional area 22 (a part of the structure, such as the tail) and the functional part at the corresponding position, so as to facilitate the sound signal in the set direction when the MEMS microphone is in the directional mode. Among them, the structure, shape, etc. of each functional part of the second functional area 22 can be designed in a matching manner according to actual needs. For example, the tail and the functional part of the second functional area 22 can be designed as a comb-shaped finger structure arranged and extending along the set direction to realize the collection of sound signals in this direction.

[0045] In the above embodiment, the set value of the voltage between the diaphragm structure 2 and the back electrode structure 4 is related to the distance, the facing area between the two, and the mass of the diaphragm structure 2. It can usually be designed to be about 5V to 20V, and can be specifically designed according to actual needs. Based on this, the switching between the directional mode and the omnidirectional mode of the MEMS microphone provided by the present application can be controlled by adjusting the voltage between the diaphragm structure 2 and the back electrode structure 4, and can be specifically carried out according to the use environment of the microphone, reducing the cost.

[0046] In this application, the number of the second functional regions 22 is an even number, such as two, four, six, eight, etc. Each pair is oppositely arranged on both sides of the first functional region 21, so that the second functional regions 22 can form two wings of a bionic fly ear in pairs to detect the incoming direction of sound pressure. When the sound pressure points to a pair of second functional regions 22, if both of the two second functional regions 22 move in the same direction, it is the bending mode of the diaphragm structure 2. If both of the two second functional regions 22 move in opposite directions, it is the swaying mode of the diaphragm structure 2. Its overall movement is a linear combination of the two modes. The movement of the two second functional regions 22 generates a change in the interdigital capacitance, realizing the resonance transmission of signals generated by sound pressure.

[0047] Optionally, as Figure 2 , Figures 4 to 7 shown, the second functional region 22 includes a connecting portion 221 and a first interdigital portion 222, and the functional portion is a second interdigital portion 32; when the voltage between the diaphragm structure 2 and the back electrode structure 4 is greater than a set value, the first interdigital portion 222 and the second interdigital portion 32 are inserted into each other to form an interdigital capacitance.

[0048] Specifically, in this application, the tail of the second functional region 22 can be designed as a comb-shaped first interdigital portion 222. The first interdigital portion 222 is connected to the side periphery of the first functional region 21 through the connecting portion 221. When the voltage between the diaphragm structure 2 and the back electrode structure 4 is greater than a set value, the first functional region 21 and the back electrode structure 4 are attracted to each other, and the first interdigital portion 222 and the second interdigital portion 32 can be inserted into each other to form an interdigital capacitance. Among them, the shape and mass of each connecting portion 221 can be adjusted according to actual needs, so that the diaphragm structure 2 can achieve a specific resonance frequency (for example, 20 - 20000 Hz), and the connecting portions 221 of the two paired second functional regions 22 are usually designed to have the same mass or shape, etc. In addition, the connection between the connecting portion 221 and the first functional region 21 is an elastic connection to improve the sensitivity of the microphone in the directivity mode.

[0049] Optionally, as Figures 4 to 6 shown, the connecting portion 221 is provided with a plurality of second through holes 223, and the plurality of second through holes 223 are arranged in an array.

[0050] Specifically, in this embodiment, the connecting portion 221 is provided with a plurality of second through holes 223, so that the mass of the connecting portion 221 can be adjusted by adjusting the size and quantity of the second through holes 223, etc., realizing that when the connecting portion 221 vibrates with the sound signal, the amplitude of its forced vibration is larger and the sensitivity is higher. Among them, the shape of the second through hole 223 can be circular, rectangular, triangular, etc. The plurality of second through holes 223 are arranged in an array so that the mass distribution of the connecting portion 221 is relatively uniform, facilitating the control of the accuracy of the insertion of the first interdigital portion 222 and the second interdigital portion 32.

[0051] Optionally, as Figures 1 to 2 shown, the thickness of the second interdigital portion 32 is less than that of the connecting portion 221, and there is a gap between the second interdigital portion 32 and the substrate structure 1.

[0052] Specifically, in this embodiment, by setting the thickness of the second interdigital portion 32 to be less than that of the corresponding connecting portion 221, a certain gap can be formed between the second interdigital portion 32 and the substrate structure 1 in the non-directional mode, avoiding contact or collision between the second interdigital portion 32 and the substrate, and improving the reliability of the structure.

[0053] Optionally, as Figures 4 to 6 shown, the diaphragm structure 2 further includes a plurality of corrugated film portions 23, and each connecting portion 221 is elastically connected to the periphery of the first functional region 21 through a corrugated film portion 23.

[0054] Specifically, in this embodiment, each second functional region 22 is elastically connected to the first functional region 21 through the corrugated film portion 23, so that when the first functional region 21 is attracted to the back electrode structure 4, the second functional region 22 can be suspended, and thus the interdigitation of the first interdigital portion 222 and the second interdigital portion 32 can be realized.

[0055] Optionally, as Figure 9 shown, the corrugated film portion 23 has a plurality of grooves 231 arranged in parallel, so that the connecting portion 221 and the first functional region 21 form an elastic connection.

[0056] Specifically, by adjusting the number, depth or width of the grooves 231 on the corrugated film portion 23 and other characteristics, the elastic coefficient of the corrugated film portion 23 can be adjusted, and then the amplitude of the forced vibration of the second functional region 22 can be adjusted, improving the sensitivity of the microphone.

[0057] Optionally, as Figure 1 、 Figure 2 and Figure 8 shown, a plurality of limiting posts 12 are arranged on the substrate structure 1, and the diaphragm structure 2 is stacked on the substrate structure 1 through the plurality of limiting posts 12; when the voltage between the diaphragm structure 2 and the back electrode structure 4 is greater than a set value, the limiting posts 12 can enable the second functional region 22 to form an interdigital capacitor with the corresponding functional portion.

[0058] Specifically, in this embodiment, the multiple limiting posts 12 provided on the substrate structure 1 can, on the one hand, provide vertical limitation for the diaphragm structure 2, and on the other hand, can also provide voltage for the diaphragm structure 2. Among them, the diaphragm structure 2 is designed with multiple small holes at positions corresponding to the multiple limiting posts 12. By inserting the limiting posts 12 into these small holes, the reliability of the limitation is further improved. For example, when four second functional areas 22 are provided, four rows of limiting posts 12 can be respectively provided in the edge area of the substrate structure 1 close to the first through hole 11, and four rows of small holes are respectively provided at the corresponding positions of the second functional areas 22, and the limiting posts 12 are inserted into the small holes one by one.

[0059] Optionally, as Figure 3 shown, a plurality of third through holes 41 are provided at positions on the back electrode structure 4 opposite to the first functional area 21; the back electrode structure 4 is provided with fourth through holes 42 at positions opposite to each second functional area 22, and the size of each fourth through hole 42 completely covers the corresponding second functional area 22.

[0060] Specifically, in this embodiment, the multiple third through holes 41 on the back electrode structure 4 enable the sound signal to be transmitted to the first functional area 21 through the multiple third through holes 41 when the microphone is in the non - directional mode, so that the first functional area 21 is forced to vibrate, thereby realizing the reception of omnidirectional sound signals. At the same time, fourth through holes 42 are provided at positions corresponding to the second functional areas 22, so that when the first functional area 21 is attracted to the back electrode structure 4, the second functional areas 22 can be suspended, achieving the purpose of forming interdigitated capacitors with the functional parts, and providing a structural basis for the switching between the two modes of the microphone.

[0061] Optionally, as Figures 4 to 6 shown, four second functional areas 22 are provided, and the four second functional areas 22 are respectively a first side portion 2201, a second side portion 2202, a third side portion 2203, and a fourth side portion 2204; among them, the first side portion 2201 and the third side portion 2203 are connected to opposite sides of the first functional area 21 along a first direction ( Figures 4 to 6 the X direction in Figures 4 to 6 ), the second side portion 2202 and the fourth side portion 2204 are connected to opposite sides of the first functional area 21 along a second direction ( the Y direction in ), and the first direction is perpendicular to the second direction.

[0062] Specifically, in this embodiment, there are four second functional regions 22, and each second functional region 22 can be elastically connected to the periphery of the first functional region 21 through a corresponding diaphragm portion 23. When the microphone is in the directional mode (the voltage between the back electrode structure 4 and the diaphragm structure 2 is greater than or equal to the specified value), it can receive sound signals in the first direction and the second direction. When the microphone is in the non-directional mode, a parallel plate capacitor is formed between the first functional region 21 and the back electrode structure 4 to receive sound signals in all directions.

[0063] In the above structure, the working principle of the microphone refers to Figure 10 , where the four second functional regions 22 are respectively recorded as the first side portion 2201, the second side portion 2202, the third side portion 2203, and the fourth side portion 2204. Sound waves come to the diaphragm structure 2 at an angle φ with the horizontal plane, causing the first side portion 2201 and the third side portion 2203 to rotate clockwise by an angle θ 1 , and the second side portion 2202 and the fourth side portion 2204 to rotate counterclockwise by an angle θ 2 , and F is the sound pressure received by each side portion.

[0064] Analysis shows that only when the connecting portions 221 of each side portion vibrate up and down has a greater impact on the capacitance value of the corresponding interdigital capacitor, while the left and right rotation has a smaller impact on the final electrical output. After calculation, the frequency response output by the system is:

[0065]

[0066] Due to the small size of the MEMS microphone, the amplitude attenuation of the sound wave propagation in each connecting portion 221 is very small, so it is considered that there is a delay relationship between F i , and let:

[0067] F i (t) = F(t - t di ).

[0068] We get:

[0069]

[0070] It can be seen that the output amplitude is proportional to the delay difference, and the difference in the acoustic path length between each connecting portion 221 is proportional to the delay difference (the ratio is the speed of sound).

[0071] After calculation, the differences in the acoustic path lengths between the connecting portion 221 of the first side portion 2201 and the connecting portion 221 of the third side portion 2203, and between the connecting portion 221 of the second side portion 2202 and the connecting portion 221 of the fourth side portion 2204 are respectively: 2Lcosφ, 2Lsinφ.

[0072] Therefore, θ 1 , θ2 The magnitude of the output amplitude is also proportional to cosφ and sinφ.

[0073] The two finally obtained frequency response formulas are respectively the angle measurement formulas on the two planes where the two sets of connecting parts 221 are located. According to θ 1 and θ 2 Analyze to obtain the angle of the sound wave in three-dimensional space, so as to realize the measurement of the direction of the sound wave in the three-dimensional space.

[0074] The specific method can be:

[0075] Calculate: and The division of the two is tanφ.

[0076] According to the second aspect of the present application, there is provided an electronic device, including: the MEMS microphone of the first aspect.

[0077] Specifically, in this embodiment, when the MEMS microphone provided in the first aspect is applied to an electronic device, it is possible to collect sound signals in two modes, namely, a directional mode and an omnidirectional mode, without setting an additional microphone, which reduces the manufacturing cost of the electronic device. Among them, the electronic device can be a tablet computer, a mobile phone, etc.

[0078] In the above embodiments, the differences between the various embodiments are mainly described. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the writing, it will not be elaborated here.

[0079] Although some specific embodiments of the present application have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for the purpose of illustration and not for the purpose of limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A MEMS microphone, characterized in that: include: A substrate structure, wherein a first through hole is disposed at the center of the substrate structure; A diaphragm structure, wherein the diaphragm structure is stacked on one side of the substrate structure and opposite to the first through hole, the diaphragm structure comprises a first functional area located in the center and a plurality of second functional areas connected to the periphery of the first functional area and arranged in pairs, and each pair of the second functional areas is respectively located on two opposite sides of the first functional area; A support structure, the support structure is stacked on one side of the substrate structure and surrounds the outer side of the diaphragm structure, the support structure includes a support portion and a plurality of functional portions corresponding to the plurality of second functional areas; A back pole structure, which is stacked on a side of the support structure away from the substrate structure and can form a parallel plate capacitor with the first functional area, and when the voltage between the diaphragm structure and the back pole structure is greater than or equal to a set value, the first functional area can be attracted to the back pole structure, so that the second functional area can form a finger capacitor with the corresponding functional part.

2. The MEMS microphone according to claim 1, characterized in that: The second functional area includes a connecting portion and a first interdigital portion, and the functional portion is the second interdigital portion; When the voltage between the diaphragm structure and the back electrode structure is greater than a set value, the first interdigital portion and the second interdigital portion are interlocked with each other to form the interdigital capacitor.

3. The MEMS microphone according to claim 2, characterized in that: The connecting portion is provided with a plurality of second through holes, and the plurality of second through holes are arranged in an array.

4. The MEMS microphone according to claim 2, characterized in that: The second interdigital portion has a thickness smaller than that of the connecting portion and has a gap between the second interdigital portion and the substrate structure.

5. The MEMS microphone according to claim 2, characterized in that: The diaphragm structure further includes a plurality of diaphragm portions, and each of the connecting portions is elastically connected to the peripheral side of the first functional area through one of the diaphragm portions.

6. The MEMS microphone according to claim 5, characterized in that: The patterned membrane portion has a plurality of grooves arranged in parallel, so that the connecting portion is elastically connected to the first functional area.

7. The MEMS microphone according to claim 1, characterized in that: A plurality of limiting posts are arranged on the substrate structure, and the diaphragm structure is stacked on the substrate structure through the plurality of limiting posts; When the voltage between the diaphragm structure and the back pole structure is greater than a set value, the limiting column can enable the second functional area and the corresponding functional part to form the interdigital capacitor.

8. The MEMS microphone according to claim 1, characterized in that: A plurality of third through holes are arranged on the back electrode structure at positions opposite to the first functional area; The back pole structure is provided with a fourth through hole at a position opposite to each of the second functional regions, and the size of each of the fourth through holes completely covers the corresponding second functional region.

9. The MEMS microphone according to claim 1, characterized in that: There are four second functional areas, and the four second functional areas are respectively a first side portion, a second side portion, a third side portion and a fourth side portion; The first side portion and the third side portion are connected to two opposite sides of the first functional area along a first direction, the second side portion and the fourth side portion are connected to two opposite sides of the first functional area along a second direction, and the first direction is perpendicular to the second direction.

10. An electronic device, characterized in that: include: The MEMS microphone according to any one of claims 1 to 9.

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