MEMS chip, microphone and electronic equipment
By setting up a projection on the back plate of the MEMS chip and limiting its area, the reliability problems of the MEMS chip are solved, and higher diaphragm separation capabilities and lower risk of damage are achieved, thereby improving the overall performance of the chip.
Patent Information
- Application Number
- CN202510151255.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-11
- Publication Date
- 2025-05-23
AI Technical Summary
The existing MEMS chips are gradually difficult to meet the demand in terms of reliability, especially during the contact and separation of the diaphragm and the insulating layer, resulting in the chip being easily damaged.
By providing a protruding portion on the back plate of the MEMS chip and limiting the area of the second surface to the area of the first surface, the contact area between the protruding portion and the diaphragm is reduced, the separation ability of the diaphragm is improved, and the risk of the diaphragm being punctured is reduced.
This technical solution effectively improves the reliability of the MEMS chip, reduces the contact area between the diaphragm and the backplate, reduces the probability of chip damage, and improves the sensitivity of the chip.
Smart Images
Figure CN120034809A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of acoustic-electric conversion equipment, and in particular to a MEMS chip, a microphone and an electronic device. Background Art
[0002] With the progress of society and the development of technology, in recent years, the size of electronic products such as mobile phones and laptops has been continuously reduced, and people have higher and higher performance requirements for these portable electronic products, which also requires the size of the electronic parts that match them to be continuously reduced, and the performance and consistency to be continuously improved. MEMS microphones integrated by MEMS (Micro-Electro-Mechanical-System, MEMS for short) technology have begun to be applied in large quantities to electronic products such as mobile phones and laptops. Their packaging volume is smaller than that of traditional electret microphones, so they are favored by most microphone manufacturers.
[0003] A MEMS microphone is a package structure consisting of a metal shell and a substrate (Printed Circuit Board, PCB for short). A MEMS chip is provided on the surface of the circuit board inside the package structure, and a sound hole for receiving sound signals is provided at a position of the circuit board opposite to the MEMS chip. External sound acts on the MEMS chip through the sound hole to achieve a sound input effect. As the demand for MEMS microphones increases, the demand for the reliability of MEMS chips is also increasing. The reliability performance of existing MEMS chips is gradually unable to meet the demand. Summary of the invention
[0004] The main purpose of the present invention is to provide a MEMS chip, a microphone and an electronic device, aiming to solve the technical problem of how to improve the reliability of the MEMS chip.
[0005] To achieve the above-mentioned purpose, the MEMS chip proposed in the present invention includes a substrate, a diaphragm, a back plate, an insulating connection layer and a sacrificial layer, the substrate has a sound inlet, the diaphragm is connected to the substrate through the insulating connection layer, the back plate is connected to the diaphragm through the sacrificial layer, and a sound cavity is formed between the back plate and the diaphragm; the back plate includes a conductive layer and a first insulating layer and a second insulating layer arranged on both sides of the conductive layer, the second insulating layer is arranged close to the sound cavity, the second insulating layer includes a main body and a protruding portion, the protruding portions are all located in the sound cavity, the protruding portion includes a first surface, a second surface and a side surrounding surface connecting the first surface and the second surface, the first surface is connected to the first insulating layer, and the area of the second surface is smaller than the area of the first surface.
[0006] In one embodiment, a first point and a second point are arranged at intervals along the first direction on the outer edge of the first surface, a third point and a fourth point are arranged at intervals along the first direction on the outer edge of the second surface, the first point, the second point, the third point and the fourth point are arranged in the same plane, a plane where the first point, the second point, the third point and the fourth point are located is defined as a cross section, a normal direction of the cross section, the first direction and the vibration direction are arranged perpendicular to each other, an angle between a line between the first point and the third point and the first surface is defined as α, an angle between a line between the second point and the fourth point and the first surface is defined as β, then 0°<α<90°, 0°<β<90°.
[0007] In one embodiment, the second surface is a plane.
[0008] In one embodiment, the distance from the second surface to the first surface along the vibration direction is not greater than half of the distance between the first point and the second point in the first direction;
[0009] And / or, the second surface is arranged parallel to the first surface.
[0010] In one embodiment, the second insulating layer further includes an arc-shaped protruding portion, the arc-shaped protruding portion includes a connecting surface and an arc-shaped curved surface, and the connecting surface is connected to the second surface.
[0011] In one embodiment, the point of the arc-shaped protrusion in the cross section that is farthest from the conductive layer is defined as an endpoint; the angle between the line between the endpoint and the first point and the connecting surface is defined as γ, and the angle between the line between the endpoint and the second point and the connecting surface is defined as θ, then 0°<γ<90°, 0°<θ<90°.
[0012] In one embodiment, the distance from the end point to the first surface along the vibration direction is less than half of the distance between the first point and the second point in the first direction, and the arc-shaped curved surface is concentrically arranged with the side surrounding surface and has the same curvature, so that the protrusion and the arc-shaped protrusion form an arch structure;
[0013] Alternatively, the distance from the endpoint to the first surface along the vibration direction is equal to half of the distance between the first point and the second point in the first direction, so that the protrusion and the arc-shaped protrusion form a hemispherical structure.
[0014] In one embodiment, the arc-shaped protrusion, the protrusion and the main body are integrally formed.
[0015] In one embodiment, the cross section is symmetrically arranged with the midline of the first surface as the axis of symmetry.
[0016] In one embodiment, the side surrounding surface bulges outward to form a side surrounding curved surface.
[0017] The present invention further provides a microphone, comprising a substrate and the above-mentioned MEMS chip, wherein the base is arranged on the substrate, and the substrate is provided with a sound hole connected to the sound inlet.
[0018] The present invention further provides an electronic device, comprising the above-mentioned microphone.
[0019] The technical solution of the present invention reduces the contact area between the protrusion and the diaphragm by arranging a protrusion on the main body and limiting the area of the second surface to be smaller than the area of the first surface, so that even if the diaphragm is in contact with the protrusion, it can be more easily separated, thereby improving the reliability of the MEMS chip. At the same time, since the second surface is in contact with the diaphragm as a planar structure, the risk of the diaphragm being punctured by the protrusion is reduced, thereby improving the reliability of the MEMS chip. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.
[0021] Figure 1 A schematic cross-sectional view of an embodiment of a MEMS chip provided by the present invention;
[0022] Figure 2 for Figure 1 A partial enlarged view of the middle A;
[0023] Figure 3 A schematic structural diagram of an embodiment of a spherical structure composed of a protrusion and an arc-shaped protrusion provided by the present invention;
[0024] Figure 4 A schematic structural diagram of an embodiment of an arch structure composed of a protrusion and an arc-shaped protrusion provided by the present invention;
[0025] Figure 5 A schematic structural diagram of an embodiment of a protrusion provided by the present invention.
[0026] Description of Figure Numbers:
[0027] 100. MEMS chip; 1. substrate; 11. sound inlet; 2. diaphragm; 3. back plate; 31. conductive layer; 32. first insulating layer; 33. second insulating layer; 331. main body; 332. raised portion; 3321. first surface; 3322. second surface; 3323. side surface; 333. arc-shaped raised portion; 3331. arc-shaped curved surface; 4. insulating connecting layer; 5. sacrificial layer; 61. first point; 62. second point; 63. third point; 64. fourth point; 7. endpoint; 8. acoustic cavity.
[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0030] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.
[0031] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.
[0032] With the progress of society and the development of technology, in recent years, the size of electronic products such as mobile phones and laptops has been continuously reduced, and people have higher and higher performance requirements for these portable electronic products, which also requires the size of the electronic parts that match them to be continuously reduced, and the performance and consistency to be continuously improved. MEMS microphones integrated by MEMS (Micro-Electro-Mechanical-System, MEMS for short) technology have begun to be applied in large quantities to electronic products such as mobile phones and laptops. Their packaging volume is smaller than that of traditional electret microphones, so they are favored by most microphone manufacturers.
[0033] A MEMS microphone is a package structure consisting of a metal shell and a substrate (Printed Circuit Board, PCB for short). A MEMS chip is provided on the surface of the circuit board inside the package structure, and a sound hole for receiving sound signals is provided at the position of the circuit board opposite to the MEMS chip. External sound acts on the MEMS chip through the sound hole to achieve the sound input effect. As the demand for MEMS microphones increases, the demand for the reliability of MEMS chips is also increasing. The reliability performance of existing MEMS chips is gradually unable to meet the demand.
[0034] The inventors have discovered that the protrusions on the insulating layer on the back plate of existing MEMS chips are generally cylindrical. When the cylindrical protrusions come into contact with the diaphragm, due to their larger contact surface, it is difficult to separate the diaphragm from the protrusions on the insulating layer. Once the diaphragm is completely attached to the back plate, the MEMS chip will be damaged. Therefore, the traditional cylindrical protrusions lead to lower reliability of the MEMS chip.
[0035] The present invention provides a MEMS chip, aiming to solve the technical problem of how to improve the reliability of the MEMS chip.
[0036] See also Figure 1 , Figure 2 and Figure 5In one embodiment of the present invention, the MEMS chip includes a substrate 1, a diaphragm 2, a back plate 3, an insulating connection layer 4 and a sacrificial layer 5, the substrate 1 has a sound inlet 11, the diaphragm 2 is connected to the substrate 1 through the insulating connection layer 4, the back plate 3 is connected to the diaphragm 2 through the sacrificial layer 5, and a sound cavity 8 is formed between the back plate 3 and the diaphragm 2; the back plate 3 includes a conductive layer 31 and a first insulating layer 32 and a second insulating layer 33 arranged on both sides of the conductive layer 31, the second insulating layer 33 is arranged close to the sound cavity 8, the second insulating layer 33 includes a main body 331 and a protruding portion 332, the protruding portions 332 are all located in the sound cavity 8, the protruding portion 332 includes a first surface 3321, a second surface 3322 and a side surrounding surface 3323 connecting the first surface 3321 and the second surface 3322, the first surface 3321 is connected to the first insulating layer 32, and the area of the second surface 3322 is smaller than the area of the first surface 3321.
[0037] Compared with the traditional cylindrical protrusion, in the technical solution of the present invention, when the area of the first surface 3321 is the same as the area of the bottom surface or the top surface of the cylindrical protrusion, the area of the second surface 3322 in this embodiment is smaller than the area of the first surface 3321, so the area of the second surface 3322 is also smaller than the area of the bottom surface of the cylindrical protrusion (the surface where the cylindrical protrusion contacts the diaphragm 2), and the contact area between the diaphragm 2 and the second surface 3322 is smaller than the contact area between the diaphragm 2 and the cylindrical protrusion. Therefore, the protrusion of this embodiment Compared with the cylindrical protrusion, 332 reduces the contact area between the back plate 3 and the diaphragm 2, so that even if the diaphragm 2 contacts the protrusion 332, it can be separated more easily, which is convenient for the diaphragm 2 to return to a normal state, reduces the probability of damage to the MEMS chip caused by the diaphragm 2 being completely attached to the back plate 3, and improves the reliability of the MEMS chip. At the same time, since the second surface 3322 contacts the diaphragm 2 as a planar structure, the risk of the diaphragm 2 being punctured by the protrusion 332 is reduced, and the reliability of the MEMS chip is improved. It should be noted that the protrusion 332 provided in this application also effectively increases the effective capacitance area of the MEMS chip compared to the cylindrical protrusion, wherein the effective capacitance area of the MEMS chip refers to the area that actually plays a role in the capacitance calculation. It should also be noted that since the contact area between the protrusion 332 and the diaphragm 2 is reduced compared to the cylindrical protrusion, it is also found through simulation experiments that the sensitivity of the MEMS chip is also improved. It should be further explained that the MEMS chip can be applicable to a MEMS microphone chip, and can also be applicable to an accelerometer, a gyroscope, a pressure sensor, an ambient light sensor, etc., without any specific limitation here.
[0038] See also Figure 5In one embodiment, a first point 61 and a second point 62 are arranged at intervals along the first direction on the outer edge of the first surface 3321, and a third point 63 and a fourth point 64 are arranged at intervals along the first direction on the outer edge of the second surface 3322. The first point 61, the second point 62, the third point 63 and the fourth point 64 are arranged in the same plane, and the plane where the first point 61, the second point 62, the third point 63 and the fourth point 64 are located is defined as a cross section. The normal direction of the cross section, the first direction and the vibration direction are arranged perpendicular to each other. The angle between the line between the first point 61 and the third point 63 and the first surface 3321 is defined as α, and the angle between the line between the second point 62 and the fourth point 64 and the first surface 3321 is defined as β, then 0°<α<90°, 0°<β<90°. By limiting the angle between the line between the first point 61 and the third point 63 and the first surface 3321 to be between 0° and 90°, and limiting the angle between the line between the second point 62 and the fourth point 64 and the first surface 3321 to be between 0° and 90°, the shape of the protrusion 332 is restricted, so that the projection of the second surface 3322 along the vibration direction can be located inside the first surface 3321, and the outer contour of the projection of the second surface 3322 is spaced from the outer edge of the first surface 3321, so that the structure of the protrusion 332 itself is relatively stable, thereby improving the reliability of the MEMS chip. Among them, the first direction is Figure 1 The left and right directions shown, the vibration direction is Figure 1 Up and down directions shown.
[0039] In one embodiment, the second surface 3322 is a plane. Compared with the case where wrinkles or protrusions are provided on the plane structure, the second surface 3322 is a plane structure, which can effectively reduce the contact area between the second surface 3322 and the diaphragm 2, thereby making it easier for the diaphragm 2 to separate from the back plate 3 and return to a normal state.
[0040] According to one embodiment of the present invention, the second surface 3322 is a wavy surface, and the crests and troughs of the wavy surface are arranged alternately in sequence. The wavy surface is formed to make it easier for the diaphragm 2 to be separated from the second surface 3322. If the diaphragm 2 contacts the crests of the wavy surface, the contact area is smaller than that of the second surface 3322 in contact with the plane structure, and it is easier to separate from the diaphragm 2, thereby improving the stability of the MEMS chip.
[0041] See also Figure 5In one embodiment, the distance from the second surface 3322 to the first surface 3321 along the vibration direction is not greater than half of the distance between the first point 61 and the second point 62 in the first direction; the distance from the second surface 3322 to the first surface 3321 may be less than half of the distance between the first point 61 and the second point 62, or the distance from the second surface 3322 to the first surface 3321 may be equal to half of the distance between the first point 61 and the second point 62. The distance from the second surface 3322 to the first surface 3321 is controlled to ensure that the second surface 3322 has a small contact area with the diaphragm 2 without causing the second surface 3322 to easily pierce the diaphragm 2 due to the small contact area. It should be noted that the distance from the second surface 3322 to the first surface 3321 along the vibration direction is Figure 5 As shown in a, the distance between the first point 61 and the second point 62 in the first direction is Figure 5 d shown.
[0042] In one embodiment, the second surface 3322 is arranged parallel to the first surface 3321. The second surface 3322 is parallel to the first surface 3321, thereby ensuring that the surface in contact with the diaphragm 2 is a plane, and avoiding the situation where the second surface 3322 is arranged tilted relative to the first surface 3321, and the surface in contact with the diaphragm 2 is the lower part of the second surface 3322, which is prone to form a structure that pierces the diaphragm 2 due to the tilt and the structural mutation at the connection between the second surface 3322 and the side surrounding surface 3323. Therefore, ensuring that the second surface 3322 is parallel to the first surface 3321 can effectively reduce the probability of the diaphragm 2 being pierced, and improve the reliability of the MEMS chip.
[0043] See also Figures 1 to 4 In one embodiment, the second insulating layer 33 further includes an arcuate protrusion 333, and the arcuate protrusion 333 includes a connecting surface and an arcuate curved surface 3331, and the connecting surface is connected to the second surface 3322. By setting the arcuate curved surface 3331 to contact the diaphragm 2, when the first surface 3321 has the same area as the top surface or the bottom surface of the cylinder and the end of the arcuate curved surface 3331 closest to the diaphragm 2 is located in the same plane as the bottom surface of the cylindrical protrusion, the diaphragm 2 will contact the bottom surface of the cylindrical protrusion when vibrating upward, and when the vibration amplitude is the same, the diaphragm 2 will only contact the end of the arcuate curved surface 3331 closest to the diaphragm 2, that is, when the cylindrical protrusion is used, the diaphragm 2 contacts a complete plane, and when contacting the arcuate curved surface 3331, the diaphragm 2 contacts a point on the arcuate curved surface 3331, thereby effectively reducing the contact area between the diaphragm 2 and the back plate 3, and improving the reliability of the MEMS chip. It should be noted that, since the diaphragm 2 contacts the arc surface 3331 , the diaphragm 2 is not easily punctured, which effectively improves the reliability of the MEMS chip.
[0044] See also Figure 3 and Figure 4In one embodiment, the point of the arc-shaped protrusion 333 that is farthest from the conductive layer 31 in the cross section is defined as end point 7; the angle between the line between end point 7 and the first point 61 and the connection surface is defined as γ, and the angle between the line between end point 7 and the second point 62 and the connection surface is defined as θ, then 0°<γ<90°, 0°<θ<90°. By limiting the angle between the line between end point 7 and the first point 61 and the connection surface to 0° to 90°, and limiting the angle between the line between end point 7 and the second point 62 and the connection surface to 0° to 90°, the position of end point 7 is limited, ensuring that the arc-shaped protrusion 333 and the diaphragm 2 have a smaller contact area.
[0045] See also Figure 3 and Figure 4 In one embodiment, the distance from the end point 7 to the first surface 3321 along the vibration direction is less than half of the distance between the first point 61 and the second point 62 in the first direction, and the arc surface 3331 is concentrically arranged with the side surrounding surface 3323 and has the same curvature, so that the protrusion 332 and the arc protrusion 333 form an arch structure; or, the distance from the end point 7 to the first surface 3321 along the vibration direction is equal to half of the distance between the first point 61 and the second point 62 in the first direction, so that the protrusion 332 and the arc protrusion 333 form a hemispherical structure. The arc surface 3331 is concentrically arranged with the side surrounding surface 3323 and has the same curvature; ensuring that the arc surface 3331 and the side surrounding surface 3323 are concentrically arranged with the side surrounding surface 3323 and have the same curvature is to avoid a structural mutation at the connection between the arc surface 3331 and the side surrounding surface 3323, resulting in a sharp portion piercing the diaphragm 2. The connecting surface and the second surface 3322 have the same shape and size, the connecting surface and the second surface 3322 are arranged to overlap, and the connection between the arc surface 3331 and the outer peripheral surface 3323 is arranged to be smoothly transitioned. When the distance from the endpoint 7 to the first surface 3321 is equal to half of the distance between the first point 61 and the second point 62 in the first direction, the protrusion 332 and the arc-shaped protrusion 333 can be combined to form a hemispherical structure; when the distance from the endpoint 7 to the first surface 3321 is less than half of the distance between the first point 61 and the second point 62 in the first direction, the protrusion 332 and the arc-shaped protrusion 333 can be combined to form an arched structure. The distance from the endpoint 7 to the first surface 3321 along the vibration direction is Figure 3 and Figure 4 In h, the distance between the first point 61 and the second point 62 in the first direction is Figure 3 and Figure 4 In d.
[0046] In one embodiment, the arc-shaped protrusion 333, the protrusion 332 and the main body 331 are integrally formed parts, which is convenient for production and processing.
[0047] In one embodiment, the cross section is symmetrically arranged with the midline of the first surface 3321 as the symmetry axis. The cross section is symmetrically arranged with the midline of the first surface 3321 as the symmetry axis to ensure that the protrusion 332 has a more stable structure and can be more easily separated when the protrusion 332 contacts the diaphragm 2, thereby improving the reliability of the MEMS chip. Figures 3 to 5 The LL straight line is shown.
[0048] In one embodiment, the side surrounding surface 3323 bulges outward to form a side surrounding curved surface. The side surrounding surface 3323 bulges out from the line between the first point 61 and the third point 63, and the side surrounding surface 3323 also bulges out from the line between the second point 62 and the fourth point 64, thereby improving the structural strength and stability of the raised portion 332, and also ensuring that the second surface 3322 has a reasonable area to contact the diaphragm 2, thereby preventing the second surface 3322 from piercing the diaphragm 2 due to its small area. It should be noted that the side surrounding curved surface and the arc-shaped curved surface 3331 are both located outside the line between the endpoint 7 and the first point 61, and the side surrounding curved surface and the arc-shaped curved surface 3331 are both located outside the line between the endpoint 7 and the second point 62.
[0049] The present invention further provides a microphone, which includes a substrate and the above-mentioned MEMS chip, wherein a base 1 is arranged on the substrate, and a sound hole connected to a sound inlet 11 is opened on the substrate. Since the microphone adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.
[0050] The present invention also provides an electronic device, the electronic device including the microphone. Since the electronic device adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here. Among them, the electronic device can be a mobile phone, a tablet, a smart watch, etc.
[0051] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.
Claims
1. A MEMS chip, comprising a substrate, a diaphragm, a back plate, an insulating connection layer and a sacrificial layer, wherein the substrate has a sound inlet, the diaphragm is connected to the substrate through the insulating connection layer, the back plate is connected to the diaphragm through the sacrificial layer, and a sound cavity is formed between the back plate and the diaphragm; characterized in that: The back plate includes a conductive layer and a first insulating layer and a second insulating layer arranged on both sides of the conductive layer, the second insulating layer is arranged close to the sound cavity, the second insulating layer includes a main body and a raised portion, the raised portions are all located in the sound cavity, the raised portions include a first surface, a second surface and a side surrounding surface connecting the first surface and the second surface, the first surface is connected to the first insulating layer, and the area of the second surface is smaller than the area of the first surface.
2. The MEMS chip according to claim 1, characterized in that: The outer edge of the first surface is provided with a first point and a second point at intervals along the first direction, the outer edge of the second surface is provided with a third point and a fourth point at intervals along the first direction, the first point, the second point, the third point and the fourth point are arranged in the same plane, the plane where the first point, the second point, the third point and the fourth point are located is defined as a cross section, the normal direction of the cross section, the first direction and the vibration direction are arranged perpendicular to each other, the angle between the line between the first point and the third point and the first surface is defined as α, the angle between the line between the second point and the fourth point and the first surface is defined as β, then 0°<α<90°, 0°<β<90°.
3. The MEMS chip according to claim 2, characterized in that: The second surface is a plane.
4. The MEMS chip according to claim 3, characterized in that: The distance between the second surface and the first surface along the vibration direction is no greater than half of the distance between the first point and the second point in the first direction; And / or, the second surface is arranged parallel to the first surface.
5. The MEMS chip according to claim 2, characterized in that: The second insulating layer further includes an arc-shaped protruding portion, the arc-shaped protruding portion includes a connecting surface and an arc-shaped curved surface, and the connecting surface is connected to the second surface.
6. The MEMS chip according to claim 5, characterized in that: defining a point in the cross section where the arc-shaped protrusion is farthest from the conductive layer as an endpoint; Define the angle between the line between the endpoint and the first point and the connecting surface as γ, and define the angle between the line between the endpoint and the second point and the connecting surface as θ, then 0°<γ<90°, 0°<θ<90°.
7. The MEMS chip according to claim 6, characterized in that: The distance between the end point and the first surface along the vibration direction is less than half of the distance between the first point and the second point in the first direction, and the arc-shaped curved surface is concentrically arranged with the side surrounding surface and has the same curvature, so that the convex portion and the arc-shaped convex portion form an arch structure; Alternatively, the distance from the endpoint to the first surface along the vibration direction is equal to half of the distance between the first point and the second point in the first direction, so that the protrusion and the arc-shaped protrusion form a hemispherical structure.
8. The MEMS chip according to claim 5, characterized in that: The arc-shaped protrusion, the protrusion and the main body are integrally formed parts.
9. The MEMS chip according to any one of claims 2 to 8, characterized in that: The cross section is symmetrically arranged with the midline of the first surface as the axis of symmetry.
10. The MEMS chip according to any one of claims 1 to 8, characterized in that: The side surrounding surfaces bulge outwards to form side surrounding curved surfaces.
11. A microphone, characterized in that: The microphone comprises a substrate and a MEMS chip as claimed in any one of claims 1 to 10, the base is arranged on the substrate, and the substrate is provided with a sound hole connected to the sound inlet.
12. An electronic device, characterized in that: The electronic device comprises the microphone as claimed in claim 11.