A MEMS microphone

Abstract

An embodiment of the present application discloses a microelectromechanical microphone. The microphone includes: a substrate, on which a sound hole is formed; a diaphragm, which is disposed on the substrate, covers the sound hole, and includes a diaphragm main body and a vent valve. The vent valve includes a valve flap and a vent hole formed in the diaphragm main body. The valve flap is connected to the diaphragm main body in a movable manner and extends into the vent hole; a sandwich part is arranged inside the diaphragm, is clamped inside the diaphragm along the thickness direction of the diaphragm, and is at least distributed in the area where the vent valve is located; a back plate, which is arranged above the diaphragm, is arranged in parallel with the diaphragm, and a predetermined gap is left between the back plate and the diaphragm.

Description

Technical Field

[0001] This application belongs to the field of microelectromechanical technology. Specifically, this application relates to a microelectromechanical microphone. Background Art

[0002] With the rapid development of electronic technology, MEMS (Micro-Electro-Mechanical System) microphones have been increasingly widely used due to their advantages such as small size, convenient SMT (Surface Mount Technology) installation, high temperature resistance, good stability, high automation level, and suitability for mass production.

[0003] Among them, MEMS microphone products contain MEMS chips based on capacitance detection. The capacitance of the MEMS chip will generate corresponding vibrations with different sound vibrations, thereby generating a changing electrical signal to achieve the function of sound-electricity conversion.

[0004] The diaphragm of the MEMS microphone is very thin, and when it is subjected to air flow impact, collision, etc., the diaphragm may be torn, damaged, or cracked. In the prior art, those skilled in the art have tried to add various structures to the diaphragm and back plate of the MEMS microphone to provide support, protection, pressure relief, etc. for the diaphragm. However, the problem of diaphragm rupture still occurs.

[0005] Therefore, it is necessary to further improve the structure of the MEMS microphone to reduce the risk of the diaphragm cracking when it is impacted. Summary of the Invention

[0006] An object of an embodiment of this application is to provide an improved microelectromechanical microphone, which includes:

[0007] A substrate, on which a sound hole is formed;

[0008] A diaphragm, which is arranged on the substrate, covers the sound hole, includes a diaphragm main body and a relief valve. The relief valve includes a valve flap and a relief hole opened on the diaphragm main body. The valve flap is connected to the diaphragm main body in a movable manner and extends into the relief hole;

[0009] A sandwich part is arranged inside the diaphragm. The sandwich part is clamped inside the diaphragm along the thickness direction of the diaphragm, and the sandwich part is at least distributed in the area where the relief valve is located;

[0010] A back plate, which is arranged above the diaphragm, is arranged in parallel with the diaphragm, and a predetermined gap is left between the back plate and the diaphragm.

[0011] Optionally, the sandwich part is silicon nitride and / or silicon oxide;

[0012] The diaphragm main body and the valve flap are made of polysilicon.

[0013] Optionally, the sandwich part is arranged at the area on the diaphragm main body where it is connected to the valve flap.

[0014] Optionally, the sandwich part is arranged in the valve flap and the diaphragm main body, and the sandwich part extends from inside the valve flap to inside the diaphragm main body.

[0015] Optionally, on both sides of the connection between the valve flap and the diaphragm main body, stress concentration areas are formed on the diaphragm main body, and the sandwich part is arranged in the stress concentration areas.

[0016] Optionally, a sandwich part is arranged inside the diaphragm main body around the air release hole.

[0017] Optionally, the valve flap is in a tilted and open posture relative to the air release hole.

[0018] Optionally, a sandwich part is arranged at the connection between the valve flap and the diaphragm main body, and the internal stresses in the diaphragm are different on the upper side and the lower side of the sandwich part.

[0019] Optionally, along the thickness direction of the diaphragm, the sandwich part is close to the upper side surface or the lower side surface of the diaphragm.

[0020] Optionally, support columns are formed on the side of the back plate facing the diaphragm;

[0021] In the area of the diaphragm corresponding to the support columns, a sandwich part is arranged inside the diaphragm.

[0022] Optionally, the diaphragm material above the sandwich part does not contact the diaphragm material around and below the sandwich part.

[0023] One technical effect of the embodiment of the present application is that the air release valve arranged on the diaphragm can play a good air release role and reduce the risk of the diaphragm breaking under the action of air flow impact. The sandwich part improves the structural strength of the diaphragm at the air release valve and ensures structural stability.

[0024] Through the following detailed description of the exemplary embodiments of the present application with reference to the drawings, other features and advantages of the present application will become clear. Brief Description of the Drawings

[0025] The drawings incorporated in the specification and constituting a part of the specification illustrate the embodiments of the present application and, together with the description, are used to explain the principles of the present application.

[0026] Figure 1 It is a schematic side cross-sectional view of the MEMS microphone provided by the embodiment of the present application;

[0027] Figure 2 A top view schematic diagram of the diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0028] Figure 3 A side cross-sectional schematic diagram of the diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0029] Figure 4 A top view schematic diagram of the diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0030] Figure 5 A top view schematic diagram of another diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0031] Figure 6 A top view schematic diagram of the diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0032] Figure 7 A top view schematic diagram of the diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0033] Figure 8 A side cross-sectional schematic diagram of the diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0034] Figure 9 A side schematic diagram of the diaphragm of the MEMS microphone provided by the embodiment of the present application;

[0035] Figure 10 A schematic diagram of the process of the MEMS microphone provided by the embodiment of the present application;

[0036] Figure 11 A schematic diagram of the process of the MEMS microphone provided by the embodiment of the present application;

[0037] Figure 12 A schematic diagram of the process of the MEMS microphone provided by the embodiment of the present application. Detailed implementation manners

[0038] 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 values set forth in these embodiments do not limit the scope of the present application.

[0039] 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.

[0040] Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the specification.

[0041] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0042] It should be noted that like reference numerals and letters refer to like items in the following figures. Therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0043] The present application provides a microelectromechanical microphone. The present application has strengthened and improved the diaphragm of the microelectromechanical microphone by adding a sandwich part in the diaphragm, thereby reinforcing the structurally vulnerable parts of the diaphragm, achieving improved structural reliability of the diaphragm and reducing the risk of cracks and ruptures in the diaphragm.

[0044] As Figure 1 shown, the microelectromechanical microphone includes a substrate 1, a diaphragm 2, a sandwich part 24, and a backplate 3. The substrate 1 is a substrate structure of the microelectromechanical microphone, which is used to carry other structural components. A sound hole 11 is formed on the substrate 1, and the sound hole 11 is used for sound to pass through and reach the components of the microelectromechanical microphone, so that the microelectromechanical microphone can convert sound vibrations into mechanical vibrations and electrical signals.

[0045] The diaphragm 2 is disposed on the substrate 1. The diaphragm 2 can be directly disposed on the substrate 1 or indirectly fixed on the substrate 1 through an isolation layer, a support layer, etc. The substrate 1 is used to provide support for the diaphragm 2 and the backplate 3 components. The present application does not limit whether the substrate 1 supports the diaphragm 2 directly or indirectly. The diaphragm 2 covers the sound hole 11. As Figure 1 shown, the sound vibrations transmitted through the sound hole 11 can act on the diaphragm 2, thereby driving the diaphragm 2 to vibrate.

[0046] As Figure 1 and Figure 2 shown, the diaphragm 2 includes a diaphragm body 21 and a relief valve. The diaphragm body 21 is the overall structure of the diaphragm, which represents the main part of the film in the present application. It has an edge region sandwiched between structural layers and a suspended region extending above the sound hole 11. The relief valve refers to a valve-like structure disposed on the diaphragm body 21, which can be opened to a certain extent to relieve pressure in a timely manner when the diaphragm 2 is subjected to strong air flow impacts, reducing the risk of diaphragm rupture.

[0047] The relief valve includes a valve flap 23 and a vent hole 22. The vent hole 22 is opened on the diaphragm body 21. The vent hole 22 is a through hole on the diaphragm body 21. As Figure 1 and Figure 2As shown. The valve flap 23 is entirely located at the air vent 22. When it is flush with the air vent 22, it can block a large part of the air vent 22 or cover the entire air vent 22. The valve flap 23 is connected to the diaphragm main body 21, that is, the valve flap 23 is connected to the diaphragm main body 21 at the edge of the air vent 22. The connection form between the valve flap 23 and the diaphragm main body 21 is flexible and movable. When the valve flap 23 is impacted by air flow, it can deflect or open upward or downward, so that the air vent 22 is partially or completely opened, allowing a large air flow to quickly pass through the air vent 22. Through the movable connection between the valve flap 23 and the diaphragm main body 21, the valve flap 23 can extend into the air vent 22 and open and close relative to the air vent 22.

[0048] As Figure 3 shown, a sandwich part 24 is arranged inside the diaphragm. The sandwich part 24 is clamped inside the diaphragm 2 along the thickness direction of the diaphragm 2. The sandwich part 24 is used to improve the structural strength of the diaphragm 2 and reduce phenomena such as rupture and tearing of the diaphragm. In the area where the air release valve is located, the diaphragm is particularly prone to cracks and ruptures because the structures of the air release port and the valve flap 23 are likely to form structural phenomena such as stress concentration and structural weakness. For example, at the edge of the position where the valve flap 23 and the diaphragm main body 21 are located, a structure prone to tearing will be formed in the area close to the air vent. When impacted, the valve flap 23 and the air vent 22 are more likely to be torn apart. In the technical solution of the present application, the area where the air release valve is located refers to the area on the diaphragm 2 close to the valve flap 23 and the air vent 22. In this relatively weak-structured area, the sandwich part 24 can be clamped inside both the diaphragm main body 21 and the valve flap 23 to improve the structural strength and reduce the possibility of tearing.

[0049] The back plate 3 is arranged on the base 1. In Figure 1 the shown embodiment, the back plate 3 is arranged above the diaphragm 2 through a support structure. The back plate 3 is parallel to the diaphragm 2, and a predetermined gap is left between the back plate 3 and the diaphragm. The predetermined gap leaves space for the vibration of the diaphragm 2 and also leaves space for the opening of the valve flap 23 on the diaphragm 2.

[0050] In the present application, an air release valve is arranged on the diaphragm. When the diaphragm is impacted by a large air flow, the air pressure can be quickly released through the opening of the air release valve, reducing the risk of the diaphragm being broken through. Further, for the weak structure formed by arranging the air release valve, the diaphragm main body and the valve flap are strengthened by arranging a sandwich inside the diaphragm. The sandwich part can be used to reinforce the weak structure generated by arranging the valve flap and reduce the risk of its rupture. Thus, the present application comprehensively improves the diaphragm of the MEMS microphone, strengthens the diaphragm from multiple aspects, and ensures the structural stability of the diaphragm.

[0051] The diaphragm 2 can be made of polysilicon to facilitate ensuring its electrical conductivity. Both the diaphragm body 21 and the valve flap 23 can be made of polysilicon. The diaphragm can form a capacitive structure with the back plate 3. When the diaphragm 2 vibrates, the capacitance changes, achieving the function of acoustic-electric conversion. Optionally, the interlayer portion 24 can be made of silicon nitride and / or silicon oxide materials. On the one hand, the structural strength of silicon nitride and silicon oxide is relatively large, which can better strengthen the diaphragm. On the other hand, silicon nitride and silicon oxide are usually non-conductive, and setting them in the inner layer of the diaphragm will not affect the electrical performance of the diaphragm.

[0052] Optionally, as Figure 4 shown, the interlayer portion 24 can be arranged at the area where the diaphragm body 21 is connected to the valve flap 23. When the valve flap 23 is subjected to a large impact, there is a possibility of being lifted upward as a whole. This position and attitude form a tendency to tear the valve flap 23 from the diaphragm body 21. Repeated occurrence of such air flow impacts may cause the valve flap 23 to be torn from the diaphragm body 21. In response, the interlayer portion 24 can be arranged on the diaphragm body 21. At the position where the valve flap 23 may open and tear, the structure of the diaphragm body 21 is strengthened, so that the acting force for lifting the valve flap 23 cannot damage the diaphragm body 21. Optionally, as Figure 4 shown, the width of the interlayer portion 24 can be greater than the width of the connection between the valve flap 23 and the diaphragm body 21. In this way, the part with a tearing tendency is completely penetrated by the interlayer portion 24, further reducing the risk of damage.

[0053] Optionally, as Figure 2 shown, the interlayer portion 24 can also extend from inside the diaphragm body 21 to inside the valve flap 23 all the time. Most of the structure of the valve flap 23 hangs in the air vent hole 22 and is only connected to the diaphragm body 21 through a part of the structure. This part of the structure is relatively weak and there is a possibility of rupture. In response, the interlayer portion 24 can be arranged in the diaphragm body 21, and further extend the interlayer portion 24 into the valve flap 23 to strengthen the connection structure between the valve flap 23 and the diaphragm body 21. Figure 8 shows the side sectional structure of the above-mentioned interlayer portion 24. When the valve flap 23 bends upward and opens, the interlayer portion 24 extending into the valve flap 23 can also bend upward accordingly.

[0054] Optionally, the technical solution can control the dimension of the interlayer portion extending into the valve flap, thereby adjusting the opening performance of the valve flap. When the dimension of the interlayer portion extending into the valve flap is less than or equal to one-third of the dimension of the valve flap extending outward from the diaphragm body, the opening action of the valve flap is less affected by the interlayer portion, and the valve flap can form a large-angle opening posture when subjected to a large impact. If the dimension of the interlayer portion extending into the valve flap is greater than one-half of the dimension of the valve flap extending outward from the diaphragm body, the interlayer portion can limit the opening degree of the valve flap, reducing the potential risk of structural damage caused by the repeated large-angle opening of the valve flap. In the above setting method, the valve flap can usually be restricted to an opening posture with a maximum of 50° to 60°, reducing the possibility of being completely lifted.

[0055] On both sides of the connection between the valve flap 23 and the diaphragm body, stress concentration areas 25 are likely to form on the diaphragm body. As Figure 5 shown, no matter whether the structure on both sides of the root of the valve flap 23 is linear or arc-shaped, the phenomenon that the stress concentration area 25 will be subjected to greater force when the valve flap 23 opens cannot be completely changed. In this regard, an interlayer portion 24 can be provided in the stress concentration area 25 of the diaphragm body 21 to improve the structural strength of the entire stress concentration area 25. When a relatively complex structure is adopted on both sides of the connection of the valve flap 23, the interlayer portion 24 can be set at a certain distance from the edge of the air discharge hole 22 and from the connection of the valve flap 23 to reduce the process difficulty of setting the interlayer portion 24. When a linear structure or a simple arc structure is adopted on both sides of the connection of the valve flap 23, the interlayer portion 24 can be directly adjacent to the edge of the air discharge hole 22 and adjacent to the connection of the valve flap 23 and the diaphragm body 21, as Figure 6 shown.

[0056] Optionally, as Figure 7 shown, an interlayer portion 24 can also be provided around the air discharge hole 22. The interlayer portion 24 is provided at the position around the air discharge hole 22 of the diaphragm body 21. The air discharge hole 22 penetrates through the diaphragm body 21. In the processing technology, relatively weak structural points are likely to form at the edge of the air discharge hole 22 due to problems such as etching. Moreover, the opening of the air discharge hole 22 also affects the structural strength of the entire diaphragm body 21. Arranging the interlayer portion 24 around the air discharge hole 22 on the diaphragm body 21 can more effectively improve the structural stability of the entire diaphragm and reduce the risk of damage.

[0057] Optionally, the valve flap 23 can be maintained in a posture of tilting up and opening relative to the diaphragm body 21 to improve the air discharge capacity of the air release valve. Optionally, by providing an interlayer portion 24 on the valve flap 23 and making the interlayer portion 24 extend from the valve flap 23 to the diaphragm body 21, the internal stress and structural characteristics of the valve flap 23 itself can be changed, so that the valve flap 23 is maintained in an upward tilting posture.

[0058] In other embodiments, the tilted structural posture can also be achieved by controlling the processing technology of the diaphragm body and the valve flap. For example, the structure of the diaphragm body and the valve flap can be divided into two layers, upper and lower layers, for deposition, and after deposition, the internal stress of the upper and lower layers of the valve flap can be changed by heat treatment or other methods, so that the valve flap tilts upward.

[0059] like Figure 8 As shown, optionally, an interlayer portion 24 is provided inside the connection between the valve flap 23 and the diaphragm body 21. By sandwiching the interlayer portion 24 and cooperating with the heat treatment process, the material on the upper and lower sides of the interlayer portion 24 can have different internal stresses. For example, since the interlayer portion 24 needs to be provided, the diaphragm 2 is divided into two layers, an upper layer material 201 and a lower layer material 202, at the location of the interlayer portion 24. During processing, the diaphragm material located at the lower layer is formed first, that is, the lower layer material 202 is formed first. Then the interlayer portion is provided, and finally the diaphragm material located at the upper layer is provided, that is, finally the upper layer material 201 is formed. Among them, different heat treatments are performed on the upper layer material 201 and the lower layer material 202 so that they have different internal stresses inside. In this way, after the valve flap is freely released, the valve flap will rise under the action of its own internal stress.

[0060] In addition to the heat treatment method, the thickness and position of the sandwich part can also be controlled to achieve the above-mentioned warping purpose. Figure 8 As shown, along the thickness direction of the diaphragm 2, the interlayer portion 24 can be offset upward by a certain thickness, or offset downward by a certain thickness, so that the material of the interlayer portion 24 occupies different thickness positions. Since the materials in the thickness direction of the structure here are different, the internal stress itself will be different, and the material of the interlayer portion usually has a higher strength than the diaphragm material. Therefore, if the interlayer portion has a certain offset in the thickness direction, it will cause the overall structure of the diaphragm to have uneven internal stress in the thickness direction. This method can also cause the valve flap 23 to be tilted to a certain extent. Figure 8 The method shown is to offset the interlayer part 24 downward by a certain distance in the thickness direction. The upper layer material 201 above the interlayer part 24 is thicker, and the diaphragm material is more flexible and easier to bend. The interlayer part 24 located at the lower position has a higher structural strength and is not easy to deform. In this way, the deformation of the upper side of the diaphragm is greater, and the valve flap 23 is more likely to bend upward.

[0061] This technical solution can combine the above-mentioned methods of setting the interlayer part, offsetting the interlayer part in the thickness direction, and heat treatment to achieve the ideal technical effect of valve flap tilting, and control the opening and tilting angles of the valve flap.

[0062] like Figure 1As shown, support posts 31 may be provided on the back plate 3. The support posts 31 are located on the surface of the back plate 3 facing the diaphragm, as Figure 1 shown, the support posts 31 extend downward. The support posts 31 are used to prevent the diaphragm 2 from adsorbing and adhering to the back plate 3. When the diaphragm 2 is impacted by a strong air flow or strongly vibrated, the diaphragm 2 may float upward and collide with the back plate 3. In this case, the diaphragm 2 may adhere to the back plate 3 and thus cannot be separated, and the function of the microphone is severely damaged. By providing the support posts 31, in the case of the above collision, the diaphragm can be stopped by the support posts 31, and only the ends of the support posts 31 will contact the diaphragm, and the diaphragm will not contact and adsorb to the plane of the back plate as a whole. In this way, the basic function of the microphone will not fail.

[0063] Further optionally, the above-mentioned sandwich portion 24 may be provided at the position of the diaphragm 2 corresponding to the support posts 31, as Figure 9 shown. When the diaphragm moves upward and collides with the back plate, the support posts 31 will stop the diaphragm. The diameter of the support posts 31 is relatively small, so the diaphragm may also be damaged. For this reason, by providing the sandwich portion 24 on the diaphragm, the risk of the support posts 31 piercing the diaphragm can be reduced. The area of the sandwich portion 24 on the diaphragm may be slightly larger than the diameter of the support posts. The sandwich portion covers a part of the area at the region of the diaphragm corresponding to the support portion, strengthening the strength of the region of the diaphragm corresponding to the support posts and improving the anti-impact and anti-rupture performance of the diaphragm. Optionally, for such a sandwich portion, its radial dimension may be 2 to 3 times the diameter of the support posts. The radial dimension of the sandwich portion refers to the diameter, side length, etc. of the sandwich portion.

[0064] In this technical solution, the diaphragm can be formed by double-layer deposition, that is, first form a layer of diaphragm material, that is, the lower layer material 202, as Figure 10 shown. Then, deposit and form the sandwich portion 24 in the required area, as Figure 11 shown. For example, the sandwich portion 24 can be deposited and formed in the area where the air release valve is located; the sandwich portion 24 can be formed in the area corresponding to the support posts on the back plate. The sandwich portion 24 protrudes upward from the first layer of diaphragm material. Finally, another layer of diaphragm material, that is, the upper layer material 201, can be deposited to form a complete diaphragm, as Figure 12 shown. Since the sandwich portion 24 is interposed in some areas between the lower layer material 202 and the upper layer material 201, the thickness of the diaphragm can be slightly increased at the position where the sandwich portion 24 is provided, as Figure 3 shown. This also helps to improve the overall structural reliability of the diaphragm.

[0065] Optionally, as Figure 9As shown, for the interlayer portion 24 corresponding to the position of the support column, the upper layer material 201 above it preferably does not form a contact or connection relationship with the surrounding of the interlayer portion 24 and the lower layer material 202 below the interlayer portion. That is, the upper layer material 201 located on the side of the interlayer portion close to the back plate can be disconnected from the diaphragm material at other positions by means of etching or the like during the processing. This structural feature has two advantages. First, when the interlayer portion and the upper layer material 201 collide with the support column, the generated acting force and deformation are not easily transmitted to the surrounding diaphragm body, reducing the risk of damage to the diaphragm body. Second, the support column is formed on the back plate, and the back plate is used to form a capacitive structure with the diaphragm. There is a risk of capacitive short circuit when the support column contacts the interlayer portion and the upper layer material 201. Disconnecting the upper layer material 201 on the interlayer portion from the surrounding diaphragm material can reduce the short circuit risk and ensure the performance of the diaphragm and the microphone itself.

[0066] 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 illustration and not for 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 microelectromechanical microphone, characterized in that, Comprising: A substrate, on which sound holes are formed; A diaphragm, which is arranged on the substrate and covers the sound holes. The diaphragm includes a diaphragm body and a relief valve. The relief valve includes a valve flap and a relief hole formed in the diaphragm body. The valve flap is connected to the diaphragm body in a movable manner and extends into the relief hole; A sandwich part is arranged inside the diaphragm. The sandwich part is sandwiched inside the diaphragm along the thickness direction of the diaphragm, and the sandwich part is at least distributed in the area where the relief valve is located; A back plate, which is arranged above the diaphragm. The back plate is arranged in parallel with the diaphragm, and a predetermined gap is left between the back plate and the diaphragm; Support columns are formed on one side of the back plate facing the diaphragm; in the area of the diaphragm corresponding to the support columns, a sandwich part is arranged inside the diaphragm, and the diaphragm material above the sandwich part does not contact the diaphragm material around and below the sandwich part.

2. The microelectromechanical microphone according to claim 1, characterized in that, The sandwich part is silicon nitride and / or silicon oxide; The diaphragm body and the valve flap are polysilicon.

3. The microelectromechanical microphone according to claim 1, characterized in that, The sandwich part is arranged at the area on the diaphragm body where it is connected to the valve flap.

4. The microelectromechanical microphone according to claim 1, characterized in that, The sandwich part is arranged in the valve flap and the diaphragm body, and the sandwich part extends from inside the valve flap into the diaphragm body.

5. The microelectromechanical microphone according to claim 1, characterized in that, On both sides of the connection between the valve flap and the diaphragm body, stress concentration areas are formed on the diaphragm body, and the sandwich part is arranged in the stress concentration areas.

6. The microelectromechanical microphone according to claim 1, characterized in that, Around the relief hole, a sandwich part is arranged inside the diaphragm body.

7. The microelectromechanical microphone according to claim 1, characterized in that, The valve flap is in a tilted and open posture relative to the relief hole.

8. The microelectromechanical microphone according to claim 7, characterized in that, A sandwich part is arranged at the connection between the valve flap and the diaphragm body. The internal stress in the diaphragm is different on the upper side and the lower side of the sandwich part.

9. The microelectromechanical microphone according to claim 8, characterized in that, Along the thickness direction of the diaphragm, the sandwich part is close to the upper surface or the lower surface of the diaphragm.

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