Preparation method of MEMS device and MEMS device

Abstract

The invention relates to a preparation method of an MEMS device and the MEMS device, and the MEMS device comprises a substrate which comprises a first surface and a second surface which are opposite to each other; a first diaphragm located on the first surface side and including a first movable region and a first fixed region; the first protruding structure is located on the side, away from the substrate, of the first vibrating diaphragm and connected to the first movable area, the area of the cross section of the first protruding structure is decreased in the first direction, the cross section is a plane parallel to the first surface, and the first direction is the direction from the second surface to the first surface; the material of the first bulge structure comprises SiN, and the content of Si in the first bulge structure is reduced and the content of N in the first bulge structure is increased in the first direction; the first supporting structure is located on the side, away from the substrate, of the first vibrating diaphragm and connected to the first fixing area; the back polar plate is positioned on one side, far away from the first vibrating diaphragm, of the first supporting structure; wherein in the first direction, the projection of the first convex structure falls into the projection range of the back polar plate; therefore, the reliability of the device is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and particularly to a method for manufacturing a MEMS device and a MEMS device. Background Art

[0002] With the rapid development of electronic technology, micro-electro-mechanical system (MEMS) devices have been increasingly widely used due to their advantages such as small size, easy installation, high temperature resistance, good stability, high degree of automation, and suitability for mass production. Among many MEMS devices, devices such as MEMS microphones and MEMS pressure sensors utilize a capacitor formed by a diaphragm and a backplate to achieve the device functions. Specifically, the vibration of the diaphragm causes a change in the distance between the diaphragm and the backplate, thereby changing the capacitance of the capacitor. The capacitance change can be amplified and converted into an electrical signal output, thus realizing the device functions.

[0003] The deformation of the diaphragm during vibration is usually temporary and recoverable. However, in the actual manufacturing process, the diaphragm will also undergo multiple subsequent high-temperature processes after being formed, resulting in a weakened diaphragm strength. Subsequently, the diaphragm may undergo permanent deformation during vibration, causing a change in the capacitor formed by the diaphragm and the backplate and reducing the device reliability. Summary of the Invention

[0004] In view of this, embodiments of the present application provide a method for manufacturing a MEMS device and a MEMS device to solve at least one problem in the background art.

[0005] In a first aspect, embodiments of the present application provide a MEMS device, including: A substrate, including a first surface and a second surface opposite to each other; A first diaphragm, located on the side of the first surface. The first diaphragm includes a first movable region and a first fixed region located outside the first movable region; A first convex structure, located on the side of the first diaphragm away from the substrate and connected to the first movable region. The cross-sectional area of the first convex structure decreases along a first direction, the cross-section is a plane parallel to the first surface, and the first direction is the direction from the second surface to the first surface; the material of the first convex structure includes SiN, and along the first direction, the Si content in the first convex structure decreases and the N content increases; A first support structure, located on the side of the first diaphragm away from the substrate and connected to the first fixed region; The back plate is located on the side of the first support structure away from the first diaphragm; wherein, in the first direction, the projection of the first convex structure falls within the projection range of the back plate.

[0006] Combined with the first aspect of the present application, in an alternative embodiment, it further includes: The first strengthening structure is located on the side of the first diaphragm away from the substrate. The cross-sectional area of the first strengthening structure decreases along the first direction. The first strengthening structure and the first convex structure are formed based on the same material layer in the same process; Part of the first strengthening structure is embedded in the first support structure.

[0007] Combined with the first aspect of the present application, in an alternative embodiment, in the same plane, the cross-sectional area of the first strengthening structure is larger than the cross-sectional area of the first convex structure.

[0008] Combined with the first aspect of the present application, in an alternative embodiment, it further includes: The second diaphragm is located on the side of the back plate away from the first diaphragm; The second support structure is located between the back plate and the second diaphragm to keep the second diaphragm spaced from the back plate; The through hole penetrates the back plate along the first direction; The support column includes a first support portion connected to the first diaphragm, a third support portion connected to the second diaphragm, and a second support portion connected between the first support portion and the third support portion along the first direction. The cross-sectional area of the first support portion decreases along the first direction. The cross-sectional area of the third support portion increases along the first direction. The second support portion passes through the through hole. The cross-sectional areas of both the first support portion and the third support portion are larger than the cross-sectional area of the second support portion; The first support portion and the first convex structure are formed based on the same material layer in the same process; The material of the third support portion includes SiN, and along the first direction, the Si content in the third support portion increases and the N content decreases.

[0009] Combined with the first aspect of the present application, in an alternative embodiment, the second diaphragm includes a second movable area and a second fixed area located outside the second movable area; The MEMS device further includes: a second convex structure, located on a side of the second diaphragm facing the back plate and connected to the second movable region, and a cross-sectional area of the second convex structure increases along the first direction; wherein, in the first direction, a projection of the second convex structure falls within a projection range of the back plate; The second convex structure and the third support portion are formed from the same material layer in the same process.

[0010] In a second aspect, an embodiment of the present application provides a method for manufacturing a MEMS device, the method including: Providing a substrate, the substrate including a first surface and a second surface opposite to each other; Forming a first diaphragm on the first surface side, the first diaphragm including a first movable region and a fixed region located on an outer periphery of the first movable region; Forming a first semiconductor material layer on the first diaphragm, a material of the first semiconductor material layer including SiN, and an Si content in the first semiconductor material layer decreases and an N content increases along a first direction, the first direction being a direction from the second surface to the first surface; Performing a first wet etching process on the first semiconductor material layer to form a first convex structure on the first movable region, a cross-sectional area of the first convex structure decreasing along the first direction, and the cross-section being a plane parallel to the first surface; Forming a first sacrificial layer covering the first diaphragm and the first convex structure; Forming a back plate on the first sacrificial layer; wherein, in the first direction, a projection of the first convex structure falls within a projection range of the back plate.

[0011] Combined with the second aspect of the present application, in an optional implementation manner, When performing the first wet etching process on the first semiconductor material layer, a first strengthening structure is further formed, the first strengthening structure being located on a side of the first diaphragm away from the substrate and connected to the first fixed region, and a cross-sectional area of the first strengthening structure decreasing along the first direction; After forming the back plate on the first sacrificial layer, the method further includes: removing a part of the first sacrificial layer, and a remaining part of the first sacrificial layer is formed into a first support structure located on the first fixed region, and a part of the first strengthening structure is embedded in the first support structure.

[0012] Combined with the second aspect of the present application, in an optional implementation manner, In the same plane, a cross-sectional area of the first strengthening structure is larger than a cross-sectional area of the first convex structure.

[0013] In connection with the second aspect of the present application, in an alternative embodiment, When performing the first wet etching process on the first semiconductor material layer, a first support portion is further formed, and the cross-sectional area of the first support portion decreases along the first direction; A through hole penetrating the back plate along the first direction is formed in the back plate; After forming the back plate on the first sacrificial layer, the method further includes: Forming a second sacrificial layer covering the back plate and filling the through hole; Forming a through hole penetrating the second sacrificial layer and the first sacrificial layer and passing through the through hole, and the through hole exposes the first support portion; Filling the through hole with a second semiconductor material layer to form a second support portion; Forming a third semiconductor material layer covering the second sacrificial layer and the second support portion, the material of the third semiconductor material layer includes SiN, and along the first direction, the Si content in the third semiconductor material layer increases and the N content decreases; Performing a second wet etching process on the third semiconductor material layer to form a third support portion, and the cross-sectional area of the third support portion increases along the first direction; the first support portion, the second support portion, and the third support portion are sequentially connected to form a support column, wherein the cross-sectional areas of the first support portion and the third support portion are both larger than the cross-sectional area of the second support portion; Forming a second vibration membrane on the third support portion.

[0014] In connection with the second aspect of the present application, in an alternative embodiment, the second vibration membrane includes a second movable region and a second fixed region located outside the second movable region; When performing the second wet etching process on the third semiconductor material layer, a second convex structure is further formed, and the second convex structure is located on the side of the second vibration membrane facing the back plate and is connected to the second movable region, and the cross-sectional area of the second convex structure increases along the first direction; wherein, in the first direction, the projection of the second convex structure falls within the projection range of the back plate.

[0015] In combination with the second aspect of the present application, in an alternative embodiment, before forming the second diaphragm on the third support portion, the method further includes: forming a third sacrificial layer covering the side wall of the third support portion and the second sacrificial layer, a top surface of the third sacrificial layer and a top end of the third support portion form a flat plane, the top surface of the third sacrificial layer is a surface of the third sacrificial layer away from the second sacrificial layer, and the top end of the third support portion is an end of the third support portion away from the second sacrificial layer; The second diaphragm covers the third sacrificial layer and the third support portion.

[0016] Compared with the prior art, the embodiments of the present application have the following beneficial effects: The MEMS device provided by the embodiment of the present application includes: a substrate, the substrate includes a first surface and a second surface opposite to each other; a first diaphragm, located on the first surface side, the first diaphragm includes a first movable region and a first fixed region located on the outer periphery of the first movable region; a first convex structure, located on the side of the first diaphragm away from the substrate and connected to the first movable region, the cross-sectional area of the first convex structure decreases along a first direction, the cross-section is a plane parallel to the first surface, and the first direction is the direction from the second surface to the first surface; the material of the first convex structure includes SiN, the Si content in the first convex structure decreases and the N content increases along the first direction; a first support structure, located on the side of the first diaphragm away from the substrate and connected to the first fixed region; a back plate, located on the side of the first support structure away from the first diaphragm; wherein, in the first direction, the projection of the first convex structure falls within the projection range of the back plate. Thus, by forming the first convex structure on the movable region of the first diaphragm, the thickness and strength of the movable region of the first diaphragm are increased, and the risk of permanent deformation due to insufficient diaphragm strength is reduced; the projection of the first convex structure falls within the projection range of the back plate, and the first convex structure can also be used as an anti-adhesion structure to prevent the diaphragm from adhering to the back plate during vibration, reducing the risk of device failure; moreover, the cross-sectional area of the first convex structure decreases along the first direction, while ensuring the strengthening effect of the first convex structure on the strength of the first diaphragm, the contact area between the first convex structure and the back plate is reduced, thereby shortening the contact time between the first convex structure and the back plate. After the first convex structure contacts the back plate, the first diaphragm can bounce away from the back plate faster, reducing the risk of permanent deformation of the first diaphragm due to a long contact state holding time; in addition, since the material of the first convex structure includes SiN, and the Si content in the first convex structure decreases and the N content increases along the first direction, the part of the material layer used to form the first convex structure that is farther away from the first diaphragm is more easily etched and removed. Thus, during the preparation process, the etching amount of the etching agent on the material layer increases along the first direction, and the first convex structure with a cross-sectional area decreasing along the first direction can be directly etched, making the dimensional accuracy of the first convex structure higher, the contour consistency better, and the strength higher; finally, the reliability of the device is improved.

[0017] The method for manufacturing a MEMS device provided by an embodiment of the present application includes: providing a substrate, where the substrate includes a first surface and a second surface opposite to each other; forming a first vibrating membrane on the first surface side, where the first vibrating membrane includes a first movable region and a first fixed region located on the outer periphery of the first movable region; forming a first semiconductor material layer on the first vibrating membrane, where the material of the first semiconductor material layer includes SiN, and the Si content in the first semiconductor material layer decreases and the N content increases along a first direction, and the first direction is the direction from the second surface to the first surface; performing a first wet etching process on the first semiconductor material layer to form a first convex structure on the first movable region, where the cross-sectional area of the first convex structure decreases along the first direction, and the cross-section is a plane parallel to the first surface; forming a first sacrificial layer covering the first vibrating membrane and the first convex structure; forming a back plate on the first sacrificial layer; where, in the first direction, the projection of the first convex structure falls within the projection range of the back plate. Thus, by forming the first convex structure on the movable region of the first vibrating membrane, the thickness and strength of the movable region of the first vibrating membrane are increased, and the risk of permanent deformation due to insufficient strength of the vibrating membrane is reduced; the projection of the first convex structure falls within the projection range of the back plate, and the first convex structure can also be used as an anti-adhesion structure to prevent the vibrating membrane from adhering to the back plate during vibration, reducing the risk of device failure; and, the cross-sectional area of the first convex structure decreases along the first direction, while ensuring the strengthening effect of the first convex structure on the strength of the first vibrating membrane, the contact area between the first convex structure and the back plate is reduced, thereby shortening the contact time between the first convex structure and the back plate. After the first convex structure contacts the back plate, the first vibrating membrane can bounce away from the back plate faster, reducing the risk of permanent deformation of the first vibrating membrane due to a long contact state holding time; specifically, by controlling the decrease of the Si content and the increase of the N content in the first semiconductor material layer along the first direction, the part of the first semiconductor material layer farther away from the first vibrating membrane is more easily etched and removed, so that the first convex structure with a cross-sectional area decreasing along the first direction can be directly etched, making the size accuracy of the first convex structure higher, the contour consistency better, and the strength higher; finally, the manufactured device has high reliability.

[0018] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation of the present application. In the drawings: Figure 1 It is a schematic cross-sectional structure diagram of a MEMS device provided by an embodiment of the present application; Figure 2 Schematic cross-sectional structure diagram of the first convex structure, the first strengthening structure, and the first supporting part provided for a specific example; Figure 3 Schematic cross-sectional structure diagram of the second convex structure, the second strengthening structure, and the third supporting part provided for a specific example; Figure 4 Schematic flow chart of the manufacturing method of the MEMS device provided by an embodiment of the present application; Figure 5 Schematic cross-sectional structure diagram of the first semiconductor material layer provided by an embodiment of the present application; Figure 6 Schematic cross-sectional structure diagram of the first semiconductor material layer provided for a specific example; Figure 7 Schematic cross-sectional structure diagram of the first convex structure, the first strengthening structure, and the first supporting part provided by an embodiment of the present application; Figure 8 Schematic cross-sectional structure diagram of the back plate and the second sacrificial layer provided by an embodiment of the present application; Figure 9 Schematic cross-sectional structure diagram of the through hole provided by an embodiment of the present application; Figure 10 Schematic cross-sectional structure diagram of the third semiconductor material layer provided by an embodiment of the present application; Figure 11 Schematic cross-sectional structure diagram of the third semiconductor material layer provided for a specific example; Figure 12 Schematic cross-sectional structure diagram of the second convex structure, the second strengthening structure, and the third supporting part provided by an embodiment of the present application; Figure 13 Schematic cross-sectional structure diagram of the third sacrificial layer provided by an embodiment of the present application; Figure 14 Schematic cross-sectional structure diagram of the second diaphragm provided by an embodiment of the present application; Figure 15 Schematic cross-sectional structure diagram of the back cavity provided by an embodiment of the present application.

[0020] Explanation of reference numerals: 100, substrate; 101, first surface; 102, second surface; 103, back cavity; 210, first diaphragm; 211, first movable area; 212, first fixed area; 213, first air hole; 220, second diaphragm; 221, second movable area; 222, second fixed area; 223, second air hole; 300, first semiconductor material layer; 301, first sub-layer of the first material layer; 302, second sub-layer of the first material layer; 303, third sub-layer of the first material layer; 310. First convex structure; 410. First strengthening structure; 500. Support column; 510. First support portion; 520. Second support portion; 530. Third support portion; 610. First sacrificial layer; 611. First support structure; 620. Second sacrificial layer; 621. Second support structure; 630. Third sacrificial layer; 640. Fourth sacrificial layer; 641. Third support structure; 601. First cavity; 602. Second cavity; 603. Third cavity; 604. Through hole; 700. Back plate; 710. First back - electrode insulating layer; 720. Back - electrode conductive layer; 730. Second back - electrode insulating layer; 701. Through port; 800. Third semiconductor material layer; 801. First sub - layer of the third material layer; 802. Second sub - layer of the third material layer; 803. Third sub - layer of the third material layer; 810. Second convex structure; 910. Second strengthening structure. Detailed implementation mode

[0021] The exemplary embodiments disclosed in the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the specific embodiments set forth herein. On the contrary, these embodiments are provided so that the present application can be more thoroughly understood and the scope of the present application disclosed can be completely conveyed to those skilled in the art.

[0022] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, to avoid confusion with the present application, some well - known technical features are not described; that is, not all features of the actual embodiments are described here, and the well - known functions and structures are not described in detail.

[0023] In the drawings, for clarity, the dimensions of layers, regions, elements and their relative dimensions may be exaggerated. The same reference numerals throughout the drawings denote the same elements.

[0024] When an element or layer is referred to as being “on,” “adjacent to,” “connected to,” or “coupled to” another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly adjacent to,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers. Although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below may be denoted as a second element, component, region, layer, or section without departing from the teachings of this application. And when discussing a second element, component, region, layer, or section, it does not imply that a first element, component, region, layer, or section necessarily exists in this application.

[0025] Spatial relationship terms such as “under,” “below,” “lower,” “beneath,” “above,” “upper,” etc. are used herein for convenience in describing the relationship of one element or feature shown in the figures to other elements or features. In addition to the orientation shown in the figures, spatial relationship terms are intended to include different orientations of the device in use and operation. For example, if the device in the figures is flipped, then an element or feature described as “under” or “beneath” or “below” other elements or features will be oriented “on” the other elements or features. Thus, the exemplary terms “under” and “below” can include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0026] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of this application. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. As used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0027] To fully understand this application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solutions of this application. The preferred embodiments of this application are described in detail below. However, in addition to these detailed descriptions, this application may have other embodiments.

[0028] Figure 1 This is a cross-sectional structure diagram of the MEMS device provided by the embodiment of the present application. As shown in the figure, the MEMS device includes: A substrate 100, including a first surface 101 and a second surface 102 opposite to each other; A first vibrating membrane 210, located on the side of the first surface 101. The first vibrating membrane 210 includes a first movable region 211 and a first fixed region 212 located on the outer periphery of the first movable region 211; A first convex structure 310, located on the side of the first vibrating membrane 210 away from the substrate 100 and connected to the first movable region 211. The cross-sectional area of the first convex structure 310 decreases along a first direction, and the cross-section is a plane parallel to the first surface 101. The first direction is the direction from the second surface 102 to the first surface 101; the material of the first convex structure 310 includes SiN, and the Si content in the first convex structure 310 decreases and the N content increases along the first direction; A first support structure 611, located on the side of the first vibrating membrane 210 away from the substrate 100 and connected to the first fixed region 212; A back plate 700, located on the side of the first support structure 611 away from the first vibrating membrane 210; wherein, in the first direction, the projection of the first convex structure 310 falls within the projection range of the back plate 700.

[0029] Thereby, the reliability of the MEMS device is improved. Specifically, a first convex structure 310 is formed on the first movable region 211 of the first vibration membrane 210, substantially increasing the thickness of the first vibration membrane 210, thereby increasing the strength of the first vibration membrane 210 and reducing the risk of permanent deformation due to insufficient strength of the vibration membrane; the first convex structure 310 is located in the first movable region 211 of the first vibration membrane 210 and the projection of the first convex structure 310 falls within the projection range of the back plate 700. When the first vibration membrane 210 moves towards the back plate 700, the first convex structure 310 contacts the back plate 700 instead of the first vibration membrane 210. The first convex structure 310 can be used as an anti-adhesion structure to prevent the vibration membrane from adhering to the back plate 700 during vibration, reducing the risk of device failure; moreover, the cross-sectional area of the first convex structure 310 decreases along the first direction. While ensuring the strengthening effect of the first convex structure 310 on the strength of the first vibration membrane 210, the contact area between the first convex structure 310 and the back plate 700 is reduced, thereby shortening the contact time between the first convex structure 310 and the back plate 700. After the first convex structure 310 contacts the back plate 700, the first vibration membrane 210 can bounce away from the back plate 700 faster, reducing the risk of permanent deformation of the first vibration membrane 210 due to a long contact state retention time. In addition, since the material of the first convex structure 310 includes SiN, and the Si content in the first convex structure 310 decreases and the N content increases along the first direction, the part of the material layer farther from the first vibration membrane 210 is more easily etched and removed. Thus, during the preparation process, the etching amount of the etching agent on the material layer increases along the first direction, and the remaining material layer forms the first convex structure 310 with a cross-sectional area decreasing along the first direction. The first convex structure 310 has higher dimensional accuracy, better profile consistency, higher strength, and a simple process.

[0030] In some embodiments, the MEMS device is a MEMS microphone. Of course, the present application does not exclude that the MEMS device is any other suitable device well-known to those skilled in the art, such as a pressure sensor and other devices specifically.

[0031] The substrate 100 can be a silicon substrate, or can include Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs or other compound semiconductors, or can also include multi-layer structures composed of these semiconductors, etc. Alternatively, the substrate 100 can be silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanide on insulator (S-SiGeOI), silicon germanide on insulator (SiGeOI), and germanium on insulator (GeOI), etc. Those skilled in the art can select according to needs, and this embodiment does not limit this.

[0032] Please refer to Figure 1, a back cavity 103 penetrating the substrate 100 in the first direction is formed in the substrate 100.

[0033] In some embodiments, the MEMS device further includes: a third support structure 641 located on the side of the first diaphragm 210 facing the substrate 100 and connected to the first fixed area 212; a third cavity 603, and the third support structure 641 surrounds the third cavity 603. Thus, the first diaphragm 210 is spaced apart from the substrate 100 by the third support structure 641, and the third cavity 603 provides a space for the first diaphragm 210 to move in the second direction, and the second direction is the direction from the first surface 101 to the second surface 102.

[0034] The material of the third support structure 641 may include silicon oxide. Of course, the present application does not exclude the case where the material of the third support structure 641 is other materials, and this embodiment does not limit this.

[0035] In some embodiments, a first air hole 213 penetrating the first diaphragm 210 in the first direction is formed in the first diaphragm 210.

[0036] The material of the first diaphragm 210 may include polysilicon. Of course, the present application does not exclude the case where the material of the first diaphragm 210 is other materials, and this embodiment does not limit this.

[0037] It can be understood that the first movable area 211 of the first diaphragm 210 is the part of the first diaphragm 210 that can move in the first direction or the second direction, and the first fixed area 212 of the first diaphragm 210 is connected to the first support structure 611 and the third support structure 641 and is used to fix the first diaphragm 210, which is the immovable part of the first diaphragm 210.

[0038] In some embodiments, the Si content in the first convex structure 310 decreases linearly and the N content increases linearly in the first direction. The longitudinal cross-sectional shape of the first convex structure 310 is trapezoidal, and the longitudinal cross-section is a plane parallel to the first direction. Optionally, the included angle range between the side wall of the first convex structure 310 and the bottom end of the first convex structure 310 is 30° to 60°, and the bottom end of the first convex structure 310 is the end of the first convex structure 310 facing the first diaphragm 210. Controlling the inclination angle of the side wall of the first convex structure 310 within this range is more conducive to stress conduction. Of course, the present application does not exclude the case where the included angle between the side wall of the first convex structure 310 and the bottom end of the first convex structure 310 is greater than 0° and less than 30°.

[0039] In some embodiments, the Si content in the first convex structure 310 decreases in a gradient along the first direction and the N content increases in a gradient. Optionally, the first convex structure 310 includes a plurality of first material layer sub-layers stacked along the first direction. The Si content in the first material layer sub-layers decreases layer by layer along the first direction and the N content increases layer by layer. The Si content and the N content within a single first material layer sub-layer remain unchanged. The longitudinal cross-sectional shape of the first convex structure 310 is a stepped shape. As a specific example, please refer to Figure 2 , the first convex structure 310 includes a first sub-layer 301 of the first material layer, a second sub-layer 302 of the first material layer, and a third sub-layer 303 of the first material layer stacked in sequence along the first direction. The Si content within the first sub-layer 301 of the first material layer is all X1 and the N content is all Y1. The Si content within the second sub-layer 302 of the first material layer is all X2 and the N content is all Y2. The Si content within the third sub-layer 303 of the first material layer is all X3 and the N content is all Y3; from the first sub-layer 301 of the first material layer to the third sub-layer 303 of the first material layer, the Si content decreases and the N content increases. Specifically, X1>X2>X3, and Y1<Y2<Y3.

[0040] Optionally, the number of layers of the first material layer sub-layers is greater than or equal to 3.

[0041] The material of the first support structure 611 may include silicon oxide. Of course, this application does not exclude the case where the material of the first support structure 611 is other materials, and this embodiment does not limit this.

[0042] As Figure 1 shown, the MEMS device may further include a first cavity 601. The first support structure 611 surrounds the first cavity 601. The first cavity 601 provides a space for the first vibration membrane 210 to move along the first direction. The first cavity 601 communicates with the third cavity 603 through a first air hole 213.

[0043] Optionally, the MEMS device further includes a first strengthening structure 410 located on the side of the first vibration membrane 210 away from the substrate 100. The cross-sectional area of the first strengthening structure 410 decreases along the first direction. The first strengthening structure 410 and the first convex structure 310 are formed based on the same material layer in the same process; a part of the first strengthening structure 410 is embedded within the first support structure 611.

[0044] Thus, by providing the first reinforcement structure 410 on the first diaphragm 210, the thickness of the first diaphragm 210 is further increased to strengthen the strength of the first diaphragm 210; by providing the cross-sectional area of the first reinforcement structure 410 to decrease along the first direction, stress concentration can be reduced and reliability can be improved; a part of the first reinforcement structure 410 is embedded in the first support structure 611, such that the first reinforcement structure 410 can also serve as an anchoring structure to strengthen the connection strength between the second diaphragm 220 and the second support structure 621, thereby facilitating the strengthening of the reliability of the device.

[0045] The first reinforcement structure 410 and the first protrusion structure 310 are formed based on the same material layer in the same process, saving processes and costs. It should be noted that for the specific structure of the first reinforcement structure 410, reference can be made to the description of the first protrusion structure 310 and Figure 2 which will not be elaborated here.

[0046] Optionally, in the same plane, the cross-sectional area of the first reinforcement structure 410 is larger than the cross-sectional area of the first protrusion structure 310. It can be understood that the first protrusion structure 310 is located in the first movable region 211 and may contact the back plate 700 when the first diaphragm 210 moves. The size of the first protrusion structure 310 is relatively small, which can reduce the contact time and the risk of permanent deformation of the first diaphragm 210; the first reinforcement structure 410 is located in the first fixed region 212, and setting the size of the first reinforcement structure 410 to be relatively large is more conducive to strengthening the thickness and strength of the first diaphragm 210; thus, under their combined action, the strength and anti-sticking effect of the first diaphragm 210 are strengthened synchronously, which is beneficial to improving the reliability of the device.

[0047] In some embodiments, the back plate 700 may include a first back plate insulating layer 710, a back plate conductive layer 720, and a second back plate insulating layer 730 stacked in sequence along the first direction. The materials of the first back plate insulating layer 710 and the second back plate insulating layer 730 may include silicon nitride; the material of the back plate conductive layer 720 may include polysilicon. Of course, the embodiments of the present application do not exclude the case where the materials of the first back plate insulating layer 710, the back plate conductive layer 720, and the second back plate insulating layer 730 are other materials; in addition, the materials of the first back plate insulating layer 710 and the second back plate insulating layer 730 may also be different.

[0048] In some embodiments, the MEMS device further includes: A second diaphragm 220, located on a side of the back plate 700 away from the first diaphragm 210; A second support structure 621, located between the back plate 700 and the second diaphragm 220 to space the second diaphragm 220 from the back plate 700; A through hole 701, penetrating the back plate 700 along the first direction; The support column 500 includes a first support portion 510 connected to the first diaphragm 210, a third support portion 530 connected to the second diaphragm 220, and a second support portion 520 connected between the first support portion 510 and the third support portion 530 along a first direction; the cross-sectional area of the first support portion 510 decreases along the first direction; the cross-sectional area of the third support portion 530 increases along the first direction; the second support portion 520 passes through the through-hole 701; the cross-sectional areas of both the first support portion 510 and the third support portion 530 are larger than the cross-sectional area of the second support portion 520; The first support portion 510 and the first convex structure 310 are formed based on the same material layer in the same process; The material of the third support portion 530 includes SiN, and along the first direction, the Si content in the third support portion 530 increases and the N content decreases.

[0049] Understandably, the MEMS device has a first diaphragm 210 and a second diaphragm 220, and this MEMS device can be called a "dual-diaphragm MEMS device". A support column 500 is usually arranged between the two diaphragms of the dual-diaphragm MEMS device, and the common support column 500 in the art is a vertical structure. Specifically, the longitudinal section of the support column 500 is rectangular; when the MEMS device works, the first diaphragm 210 and the second diaphragm 220 vibrate, and the stress conduction effect of the vertical support column 500 is poor, and stress concentration is likely to occur, affecting the reliability of the MEMS device. In some related technologies, by etching the first sacrificial layer for forming the first support structure 611 and the second sacrificial layer for forming the second support structure 621, a through-hole with a width larger at both ends than that in the middle part is formed, and a material is filled in the through-hole to form the support column 500. Although the width of both ends of the formed support column 500 is larger, which has a certain improvement on the support effect and stress conduction effect of the support column 500, voids will appear in the filled support column 500, and the structural precision and strength are poor, making it difficult to effectively improve the reliability of the device.

[0050] In the embodiment of the present application, it is controlled that the Si content in the first support portion 510 decreases and the N content increases along the first direction, the Si content in the third support portion 530 increases and the N content decreases, so as to change the wet etching rate. During actual preparation, the two ends of the support column 500, that is, the first support portion 510 and the third support portion 530, can be directly obtained by etching the material layer. The structural accuracy of the support column 500 is better and the support strength is higher. Moreover, the cross-sectional areas of both the first support portion 510 and the third support portion 530 are larger than the cross-sectional area of the second support portion 520. The cross-sectional area of the first support portion 510 decreases along the first direction, and the cross-sectional area of the third support portion 530 increases along the first direction. The contact area between the first support portion 510 and the first diaphragm 210 is larger, and the contact area between the third support portion 530 and the second diaphragm 220 is larger. The stress conduction effect is better, which is more conducive to avoiding stress concentration and improving the reliability of the device.

[0051] The first support portion 510 and the first protrusion structure 310 are formed based on the same material layer in the same process. Thereby, the process and cost can be saved. It should be noted that for the specific structure of the first support portion 510, reference can be specifically made to the description of the first protrusion structure 310 and Figure 2 the description thereof will not be elaborated here.

[0052] In some embodiments, the Si content in the third support portion 530 increases linearly and the N content decreases linearly along the first direction. The longitudinal cross-sectional shape of the third support portion 530 is trapezoidal. Optionally, the included angle range between the side wall of the third support portion 530 and the top end of the third support portion 530 is 30° to 60°, and the top end of the third support portion 530 is the end of the third support portion 530 facing the second diaphragm 220. Of course, the present application does not exclude the case where the included angle between the side wall of the third support portion 530 and the top end of the third support portion 530 is greater than 0° and less than 30°.

[0053] In some embodiments, the Si content in the third support portion 530 increases in a gradient manner and the N content decreases in a gradient manner along the first direction. Optionally, the third support portion 530 includes a plurality of third material layer sub-layers stacked along the first direction. The Si content in the third material layer sub-layers increases layer by layer and the N content decreases layer by layer along the first direction, and the Si content and the N content within a single third material layer sub-layer remain unchanged. The longitudinal cross-sectional shape of the third support portion 530 is stepped. As a specific example, please refer to Figure 3, the third support portion 530 includes a third material layer third sub-layer 803, a third material layer second sub-layer 802, and a third material layer first sub-layer 801 stacked in sequence along the first direction. The Si content in the third material layer first sub-layer 801 is all A1 and the N content is all B1. The Si content in the third material layer second sub-layer 802 is all A2 and the N content is all B2. The Si content in the third material layer third sub-layer 803 is all A3 and the N content is all B3; from the third material layer third sub-layer 803 to the third material layer first sub-layer 801, the Si content increases and the N content decreases. Specifically, A1 > A2 > A3, and B1 < B2 < B3.

[0054] Optionally, the number of sub-layers of the third material layer is greater than or equal to 3.

[0055] Optionally, the first support portion 510 and the third support portion 530 are symmetrically arranged with respect to the plane where the center of the second support portion 520 is located, and the plane where the center of the second support portion 520 is located is parallel to the plane where the first surface 101 is located. Thus, the two ends of the support column 500 are symmetrically arranged, the stress conduction effect of the support column 500 is better, the support effect is higher, which is beneficial to improving the device reliability. Specifically, in the first direction, the projection of the cross-section at the first position in the first support portion 510 completely overlaps with the projection of the cross-section at the second position in the third support portion 530, and the distance between the first position and the first diaphragm is equal to the distance between the second position and the second diaphragm. The thickness of the first support portion 510 is the same as the thickness of the third support portion 530.

[0056] In some embodiments, along the first direction, the Si content in the first support portion 510 decreases linearly and the N content increases linearly, and the Si content in the third support portion 530 increases linearly and the N content decreases linearly; the Si content and N content at the first position in the first support portion 510 correspond to the Si content and N content at the second position in the third support portion 530. Thus, it is beneficial to realize the symmetrical arrangement of the first support portion 510 and the third support portion 530.

[0057] In some embodiments, the Si content in the first support portion 510 decreases in a gradient along the first direction and the N content increases in a gradient; the Si content in the third support portion 530 increases in a gradient and the N content decreases in a gradient; the Si content and the N content at the first position in the first support portion 510 are correspondingly the same as the Si content and the N content at the second position in the third support portion 530. The first support portion 510 may include a plurality of first material layer sub-layers stacked along the first direction. The Si content of each first material layer sub-layer decreases layer by layer along the first direction and the N content increases layer by layer. The Si content and the N content within a single first material layer sub-layer are unchanged; the third support portion 530 includes a plurality of third material layer sub-layers stacked along the first direction. The Si content of each third material layer sub-layer increases layer by layer along the first direction and the N content decreases layer by layer. The Si content and the N content within a single third material layer sub-layer are unchanged; each first material layer sub-layer is sequentially sorted along the first direction starting from the first sub-layer of the first material layer, and the first sub-layer of the first material layer is the layer closest to the first diaphragm 210; each third material layer sub-layer is sequentially sorted along the second direction starting from the first sub-layer of the third material layer, and the first sub-layer of the third material layer is the layer closest to the second diaphragm 220; the Si content and the N content in the first material layer sub-layer with the same serial number are correspondingly the same as those in the third material layer sub-layer with the same serial number; the first material layer sub-layer and the third material layer sub-layer with the same serial number have the same thickness. The number of the first material layer sub-layers in the first support portion 510 is the same as the number of the third material layer sub-layers in the third support portion 530. In the first direction, the projections of the first material layer sub-layer and the third material layer sub-layer with the same serial number completely overlap. Thus, it is beneficial to realize the symmetric arrangement of the first support portion 510 and the third support portion 530.

[0058] As a specific example, please refer to Figure 2 and Figure 3, the first support portion 510 includes a first sub-layer 301 of the first material layer, a second sub-layer 302 of the first material layer, and a third sub-layer 303 of the first material layer stacked along the first direction. The third support portion 530 includes a third sub-layer 803 of the third material layer, a second sub-layer 802 of the third material layer, and a first sub-layer 801 of the third material layer stacked along the first direction. From the first sub-layer 301 of the first material layer to the third sub-layer 303 of the first material layer, and from the first sub-layer 801 of the third material layer to the third sub-layer 803 of the third material layer, the Si content decreases and the N content increases. The Si content and N content of the first sub-layer 301 of the first material layer are correspondingly equal to the Si content and N content of the first sub-layer 801 of the third material layer. The Si content and N content of the second sub-layer 302 of the first material layer are correspondingly equal to the Si content and N content of the second sub-layer 802 of the third material layer. The Si content and N content of the third sub-layer 303 of the first material layer are correspondingly equal to the Si content and N content of the third sub-layer 803 of the third material layer. The thickness of the first sub-layer 301 of the first material layer is correspondingly equal to the thickness of the first sub-layer 801 of the third material layer. The thickness of the second sub-layer 302 of the first material layer is correspondingly equal to the thickness of the second sub-layer 802 of the third material layer. The thickness of the third sub-layer 303 of the first material layer is correspondingly equal to the thickness of the third sub-layer 803 of the third material layer. In the first direction, the projection of the first sub-layer 301 of the first material layer completely overlaps with the projection of the first sub-layer 801 of the third material layer. The projection of the second sub-layer 302 of the first material layer completely overlaps with the projection of the second sub-layer 802 of the third material layer. The projection of the third sub-layer 303 of the first material layer completely overlaps with the projection of the third sub-layer 803 of the third material layer.

[0059] The material of the second support structure 621 may include silicon oxide. Of course, this application does not exclude the case where the material of the second support structure 621 is other materials, and this embodiment does not limit this.

[0060] Please refer to Figure 1 , the MEMS device further includes a second cavity 602, and the second support structure 621 surrounds the second cavity 602. The second cavity 602 provides a space for the second diaphragm 220 to move in the second direction. The second cavity 602 communicates with the first cavity 601 through a through-hole 701.

[0061] In some embodiments, a second air hole 223 penetrating the second diaphragm 220 in the first direction is formed in the second diaphragm 220.

[0062] The material of the second diaphragm 220 may include polysilicon. Of course, this application does not exclude the case where the material of the second diaphragm 220 is other materials, and this embodiment does not limit this.

[0063] Optionally, in the first direction, the projection of the first air hole 213 falls within the projection range of the through hole 701. Further, the projection of the first air hole 213 is located at the center of the projection of the through hole 701.

[0064] Optionally, in the first direction, the projection of the second air hole 223 falls within the projection range of the through hole 701. Further, the projection of the second air hole 223 is located at the center of the projection of the through hole 701.

[0065] Optionally, the second diaphragm 220 includes a second movable region 221 and a second fixed region 222 located on the outer periphery of the second movable region 221; the MEMS device further includes: a second convex structure 810, located on the side of the second diaphragm 220 facing the back plate 700 and connected to the second movable region 221, and the cross-sectional area of the second convex structure 810 increases along the first direction; wherein, in the first direction, the projection of the second convex structure 810 falls within the projection range of the back plate 700; the second convex structure 810 and the third support portion 530 are formed based on the same material layer in the same process.

[0066] It can be understood that the second convex structure 810 and the third support portion 530 are formed based on the same material layer in the same process, which can save processes and costs. It should be noted that for the specific structure of the second convex structure 810, reference can be specifically made to the description of the third support portion 530 and Figure 3 and no more details will be elaborated here.

[0067] Thereby, the reliability of the MEMS device is improved. Specifically, the second convex structure 810 is formed on the second movable region 221 of the second diaphragm 220, which substantially increases the thickness of the second movable region 221 of the second diaphragm 220, thereby increasing the strength of the second diaphragm 220 and reducing the risk of permanent deformation due to insufficient diaphragm strength; the projection of the second convex structure 810 falls within the projection range of the back plate 700. When the second diaphragm 220 moves towards the back plate 700, the second convex structure 810 contacts the back plate 700 instead of the second diaphragm 220. The second convex structure 810 can be used as an anti-adhesion structure to prevent the diaphragm from adhering to the back plate 700 during vibration and reduce the risk of device failure; moreover, the cross-sectional area of the second convex structure 810 increases along the first direction. While ensuring the strengthening effect of the second convex structure 810 on the strength of the second diaphragm 220, the contact area between the second convex structure 810 and the back plate 700 is reduced, thereby shortening the contact time between the second convex structure 810 and the back plate 700. After the second convex structure 810 contacts the back plate 700, the second diaphragm 220 can bounce away from the back plate 700 faster, reducing the risk of permanent deformation of the second diaphragm 220 due to a long contact state retention time.

[0068] Understandably, during actual fabrication, the Si content of the material layer can be controlled to increase along the first direction while the N content decreases, causing the wet etching rate of the material layer to decrease along the first direction. Thus, when performing the wet etching process, the etching amount of the etching agent on the material layer increases, and the remaining material layer forms a second convex structure 810 with a cross-sectional area increasing along the first direction. The second convex structure 810 has higher dimensional accuracy, higher structural strength, and a simple process.

[0069] Understandably, the second movable region 221 of the second diaphragm 220 is the part where the second diaphragm 220 can move along the first direction or the second direction. The second fixed region 222 of the second diaphragm 220 is connected to the second support structure 621 and is used to fix the second diaphragm 220, which is the immovable part of the second diaphragm 220.

[0070] Optionally, the MEMS device further includes: a second strengthening structure 910, located on the side of the second diaphragm 220 facing the back plate 700, and the cross-sectional area of the second strengthening structure 910 increases along the first direction; the second strengthening structure 910 and the third support portion 530 are formed based on the same material layer in the same process; a part of the second strengthening structure 910 is embedded in the second support structure 621.

[0071] Thus, by providing the second support structure 621 on the second diaphragm 220, the thickness of the second diaphragm 220 is further increased, strengthening the strength of the second diaphragm 220; the second strengthening structure 910 and the third support portion 530 are formed based on the same material layer in the same process, saving processes and costs. It should be noted that for the specific structure of the second strengthening structure 910, reference can specifically be made to the description of the third support portion 530 and Figure 3 and the description thereof will not be elaborated here.

[0072] Optionally, in the same plane, the cross-sectional area of the second strengthening structure 910 is larger than the cross-sectional area of the second convex structure 810. Understandably, the second convex structure 810 is located in the second movable region 221 and will contact the back plate 700 when the second diaphragm 220 moves. The size of the second convex structure 810 is relatively small, which can reduce the contact area and time, and reduce the risk of permanent deformation of the second diaphragm 220; the second strengthening structure 910 is located in the second fixed region 222, and setting the size of the second strengthening structure 910 to be relatively large is more conducive to strengthening the thickness and strength of the second diaphragm 220; thus, under the synergistic effect of the two, the strength and anti-sticking effect of the second diaphragm 220 are strengthened synchronously, further improving the device reliability.

[0073] The embodiment of the present application also provides a method for fabricating a MEMS device. Please refer to Figure 4 The fabrication method includes: Step S101: Provide a substrate, the substrate including a first surface and a second surface opposite to each other; Step S102: Form a first diaphragm on the first surface side, the first diaphragm including a first movable region and a fixed region located on the outer periphery of the first movable region; Step S103: Form a first semiconductor material layer on the first diaphragm, the material of the first semiconductor material layer including SiN, the Si content in the first semiconductor material layer decreasing and the N content increasing along a first direction, the first direction being the direction from the second surface to the first surface; Step S104: Perform a first wet etching process on the first semiconductor material layer to form a first convex structure on the first movable region, the cross-sectional area of the first convex structure decreasing along the first direction, and the cross-section being a plane parallel to the first surface; Step S105: Form a first sacrificial layer covering the first diaphragm and the first convex structure; Step S106: Form a back plate on the first sacrificial layer; wherein, in the first direction, the projection of the first convex structure falls within the projection range of the back plate.

[0074] Thus, by forming the first convex structure on the first movable region of the first diaphragm, the thickness and strength of the movable region of the first diaphragm are increased, and the risk of permanent deformation due to insufficient diaphragm strength is reduced; the projection of the first convex structure falls within the projection range of the back plate, and the first convex structure can also serve as an anti-adhesion structure to prevent the diaphragm from adhering to the back plate during vibration, reducing the risk of device failure; moreover, the cross-sectional area of the first convex structure decreases along the first direction, while ensuring the strengthening effect of the first convex structure on the strength of the first diaphragm, the contact area between the first convex structure and the back plate is reduced, thereby shortening the contact time between the first convex structure and the back plate. After the first convex structure contacts the back plate, the first diaphragm can bounce away from the back plate faster, reducing the risk of permanent deformation of the first diaphragm due to a long contact state holding time; specifically, by controlling the Si content in the first semiconductor material layer to decrease and the N content to increase along the first direction, the part of the first semiconductor material layer farther from the first diaphragm is more easily etched and removed, so that the first convex structure with a cross-sectional area decreasing along the first direction can be directly etched, making the size accuracy of the first convex structure higher, the contour consistency better, and the strength higher; ultimately, the reliability of the prepared MEMS device is improved.

[0075] First, please refer to Figure 5 , perform Step S101 to provide a substrate 100, the substrate 100 including a first surface 101 and a second surface 102 opposite to each other.

[0076] Next, the manufacturing method may further include: forming a fourth sacrificial layer 640 on the first surface 101 side.

[0077] Next, perform step S102 to form a first diaphragm 210 on the first surface 101 side. The first diaphragm 210 includes a first movable region 211 and a first fixed region 212 located on the outer periphery of the first movable region 211.

[0078] In some embodiments, the preparation method may further include: forming a first air hole 213 penetrating the first diaphragm 210 along the first direction.

[0079] Next, perform step S103 to form a first semiconductor material layer 300 on the first diaphragm 210. The material of the first semiconductor material layer 300 includes SiN. Along the first direction, the Si content in the first semiconductor material layer 300 decreases and the N content increases. Thus, by controlling the Si content and N content in the first semiconductor material layer 300, the wet etching rate of the first semiconductor material layer 300 can be controlled, and then a structure with an expected shape can be obtained when the wet etching process is performed subsequently.

[0080] During actual preparation, the change of the Si content and N content in the first semiconductor material layer 300 can be regulated by adjusting the flow rate of the Si source gas and the flow rate of the N source gas.

[0081] In some embodiments, along the first direction, the Si content in the first semiconductor material layer 300 decreases linearly and the N content increases linearly.

[0082] In some embodiments, along the first direction, the Si content in the first semiconductor material layer 300 decreases in a gradient and the N content increases in a gradient. Optionally, the first semiconductor material layer 300 includes a plurality of first material layer sub-layers stacked along the first direction. Along the first direction, the Si content in the first material layer sub-layers decreases layer by layer and the N content increases layer by layer. The Si content and N content within a single first material layer sub-layer remain unchanged. As a specific example, please refer to Figure 6 , the first semiconductor material layer 300 includes a first material layer first sub-layer 301, a first material layer second sub-layer 302, and a first material layer third sub-layer 303 stacked in sequence along the first direction. The Si content within the first material layer first sub-layer 301 is all X1 and the N content is all Y1. The Si content within the first material layer second sub-layer 302 is all X2 and the N content is all Y2. The Si content within the first material layer third sub-layer 303 is all X3 and the N content is all Y3; from the first material layer first sub-layer 301 to the first material layer third sub-layer 303, the Si content decreases and the N content increases. Specifically, X1>X2>X3, and Y1<Y2<Y3.

[0083] Optionally, the number of layers of the first material layer sub-layers is greater than or equal to 3.

[0084] Next, please refer toFigure 7 Step S104 is performed to perform a first wet etching process on the first semiconductor material layer 300 to form a first convex structure 310 on the first movable region 211. The cross-sectional area of the first convex structure 310 decreases along the first direction. Thus, by forming the first convex structure 310 on the first movable region 211 of the first diaphragm 210, the thickness of the movable region of the first diaphragm 210 is increased, and the risk of permanent deformation due to insufficient diaphragm strength is reduced.

[0085] It can be understood that the higher the Si content and the lower the N content in the SiN layer, the easier it is to be etched and removed. Therefore, along the first direction, the Si content in the first semiconductor material layer 300 decreases and the N content increases. During the process of performing the first wet etching process, along the first direction, the etching amount of the etching agent on the first semiconductor material layer 300 decreases, and the remaining first semiconductor material layer 300 constitutes the first convex structure 310 with a cross-sectional area decreasing along the first direction.

[0086] The etching agent may include hydrofluoric acid or phosphoric acid.

[0087] In some embodiments, along the first direction, the Si content in the first semiconductor material layer 300 decreases linearly and the N content increases linearly; the longitudinal cross-sectional shape of the first convex structure 310 is trapezoidal. Optionally, the included angle between the side wall of the first convex structure 310 and the bottom end of the first convex structure 310 ranges from 30° to 60°. The bottom end of the first convex structure 310 is the end of the first convex structure 310 facing the first diaphragm 210. Of course, the present application does not exclude the case where the included angle between the side wall of the first convex structure 310 and the bottom end of the first convex structure 310 is greater than 0° and less than 30°.

[0088] In some embodiments, please refer to Figure 2 and Figure 6 , the first semiconductor material layer 300 includes a plurality of first material layer sub-layers stacked along the first direction. Along the first direction, the Si content in the first material layer sub-layers decreases layer by layer and the N content increases layer by layer. The Si content and the N content within a single first material layer sub-layer are unchanged; the longitudinal cross-sectional shape of the first convex structure 310 is stepped.

[0089] Optionally, please refer to Figure 7 , when performing step S104, a first wet etching process is performed on the first semiconductor material layer 300, and a first strengthening structure 410 is also formed. The first strengthening structure 410 is located on the side of the first diaphragm 210 away from the substrate 100 and is connected to the first fixed region 212. The cross-sectional area of the first strengthening structure 410 decreases along the first direction; please refer to Figure 1, in subsequent steps, specifically after forming the back plate 700 on the first sacrificial layer 610, the above method may further include: removing a part of the first sacrificial layer 610, and the remaining first sacrificial layer 610 is formed into a first support structure 611 located on the first fixed area 212, and a part of the first strengthening structure 410 is embedded in the first support structure 611.

[0090] Thus, the first strengthening structure 410 and the first convex structure 310 are formed based on the same material layer in the same process, saving processes and costs. It should be noted that for the specific structure of the first strengthening structure 410, reference may specifically be made to the description of the first convex structure 310 and Figure 2 . Details are not described herein again.

[0091] Optionally, in the same plane, the cross-sectional area of the first strengthening structure 410 is larger than the cross-sectional area of the first convex structure 310.

[0092] It can be understood that the first convex structure 310 is located in the first movable area 211. When the first diaphragm 210 moves, it will contact the back plate 700. The size of the first convex structure 310 is relatively small, which can reduce the contact time and the risk of permanent deformation of the first diaphragm 210; the first strengthening structure 410 is located in the first fixed area 212, and setting the size of the first strengthening structure 410 to be relatively large is more conducive to strengthening the thickness and strength of the first diaphragm 210; thus, under the synergistic effect of the two, the strength and anti-adhesion effect of the first diaphragm 210 are strengthened synchronously, which is beneficial to improving the reliability of the device.

[0093] Next, please refer to Figure 8 , and perform step S105 to form a first sacrificial layer 610 covering the first diaphragm 210 and the first convex structure 310.

[0094] The material of the first sacrificial layer 610 may include silicon oxide. Of course, this application does not exclude the case where the material of the first sacrificial layer 610 is other materials, and this embodiment does not limit this.

[0095] Next, step S106 is executed to form a back plate 700 on the first sacrificial layer 610; wherein, in the first direction, the projection of the first convex structure 310 falls within the projection range of the back plate 700. Thus, the first convex structure 310 can also serve as an anti-sticking structure to prevent the diaphragm from sticking to the back plate 700 during vibration, reducing the risk of device failure; moreover, the cross-sectional area of the first convex structure 310 decreases along the first direction. While ensuring the strengthening effect of the first convex structure 310 on the strength of the first diaphragm 210, the contact area between the first convex structure 310 and the back plate 700 is reduced, thereby shortening the contact time between the first convex structure 310 and the back plate 700. After the first convex structure 310 contacts the back plate 700, the first diaphragm 210 can bounce away from the back plate 700 faster, reducing the risk of permanent deformation of the first diaphragm 210 due to a long contact state holding time.

[0096] Optionally, please refer to Figure 1 , Figures 7 to 14 , when step S104 is executed, a first wet etching process is performed on the first semiconductor material layer 300, and a first support portion 510 is also formed. The cross-sectional area of the first support portion 510 decreases along the first direction; A through hole 701 penetrating the back plate 700 along the first direction is formed in the back plate 700; After step S106 is executed to form the back plate 700 on the first sacrificial layer 610, the method further includes: Forming a second sacrificial layer 620 covering the back plate 700 and filling the through hole 701; Forming a through hole 604 penetrating the second sacrificial layer 620 and the first sacrificial layer 610 and passing through the through hole 701, and the through hole 604 exposes the first support portion 510; Filling the through hole 604 with a second semiconductor material layer to form a second support portion 520; Forming a third semiconductor material layer 800 covering the second sacrificial layer 620 and the second support portion 520. The material of the third semiconductor material layer 800 includes SiN, and the Si content in the third semiconductor material layer 800 increases and the N content decreases along the first direction; Performing a second wet etching process on the third semiconductor material layer 800 to form a third support portion 530. The cross-sectional area of the third support portion 530 increases along the first direction; the first support portion 510, the second support portion 520, and the third support portion 530 are sequentially connected to form a support column 500, wherein the cross-sectional areas of the first support portion 510 and the third support portion 530 are both larger than the cross-sectional area of the second support portion 520; Forming a second diaphragm 220 on the third support portion 530.

[0097] In the embodiments of the present application, it is controlled that the Si content in the first semiconductor material layer 300 decreases and the N content increases along the first direction, and the Si content in the third semiconductor material layer 800 increases and the N content decreases, so as to change the wet etching rate. Thus, the two ends of the support column 500, namely the first support portion 510 and the third support portion 530, can be directly obtained by etching the material layer, and it is realized that the cross-sectional areas of both the first support portion 510 and the third support portion 530 are larger than the cross-sectional area of the second support portion 520. The structural accuracy of the support column 500 is better and the support strength is higher; the cross-sectional area of the first support portion 510 decreases along the first direction, and the cross-sectional area of the third support portion 530 increases along the first direction. The contact area between the first support portion 510 and the first vibration membrane 210 is larger, and the contact area between the third support portion 530 and the second vibration membrane 220 is larger, so the stress conduction effect is better and it is more beneficial to avoid stress concentration; thus, it is beneficial to improve the reliability of the MEMS device.

[0098] In some embodiments, the Si content in the third semiconductor material layer 800 increases linearly and the N content decreases linearly along the first direction. The longitudinal cross-sectional shape of the third support portion 530 is trapezoidal. Optionally, the included angle range between the side wall of the third support portion 530 and the top end of the third support portion 530 is 30° to 60°, and the top end of the third support portion 530 is the end of the third support portion 530 facing the second vibration membrane 220. Of course, the present application does not exclude the case where the included angle between the side wall of the third support portion 530 and the top end of the third support portion 530 is greater than 0° and less than 30°.

[0099] In some embodiments, the Si content in the third semiconductor material layer 800 increases in a gradient manner and the N content decreases in a gradient manner along the first direction. Optionally, the third semiconductor material layer 800 may include a plurality of third material layer sub-layers stacked along the first direction. The Si content in the third material layer sub-layers increases layer by layer and the N content decreases layer by layer along the first direction, and the Si content and the N content within a single third material layer sub-layer remain unchanged. As a specific example, please refer to Figure 11 , the third semiconductor material layer 800 includes a third material layer third sub-layer 803, a third material layer second sub-layer 802, and a third material layer first sub-layer 801 stacked in sequence along the first direction. The Si content in the third material layer first sub-layer 801 is all A1 and the N content is all B1. The Si content in the third material layer second sub-layer 802 is all A2 and the N content is all B2. The Si content in the third material layer third sub-layer 803 is all A3 and the N content is all B3; from the third material layer third sub-layer 803 to the third material layer first sub-layer 801, the Si content increases and the N content decreases. Specifically, A1 > A2 > A3, and B1 < B2 < B3. Please refer to Figure 3 , in the first direction, the cross-sectional shape of the third support portion 530 is stepped.

[0100] Optionally, the number of sub-layers of the third material layer is greater than or equal to 3.

[0101] Optionally, the first support portion 510 and the third support portion 530 are symmetrically arranged along the plane where the center of the second support portion 520 is located, and the plane where the center of the second support portion 520 is located is parallel to the plane where the first surface 101 is located. Thus, the two ends of the support column 500 are symmetrically arranged, the stress conduction effect of the support column 500 is better, the support effect is higher, and it is beneficial to improve the device reliability. Specifically, in the first direction, the projection of the cross-section at the first position in the first support portion 510 completely overlaps with the projection of the cross-section at the second position in the third support portion 530, and the distance between the first position and the first diaphragm is equal to the distance between the second position and the second diaphragm. The thickness of the first support portion 510 is the same as the thickness of the third support portion 530.

[0102] In some embodiments, along the first direction, the Si content in the first semiconductor material layer 300 linearly decreases and the N content linearly increases, and the Si content in the third semiconductor material layer 800 linearly increases and the N content linearly decreases; the Si content and the N content at the first position in the first semiconductor material layer 300 correspond to the Si content and the N content at the second position in the third semiconductor material layer 800. The thickness of the first semiconductor material layer 300 is the same as the thickness of the third semiconductor material layer 800. Thus, it is beneficial to realize the symmetrical arrangement of the first support portion 510 and the third support portion 530.

[0103] In some embodiments, the Si content in the first semiconductor material layer 300 decreases in a gradient along the first direction and the N content increases in a gradient; the Si content in the third semiconductor material layer 800 increases in a gradient and the N content decreases in a gradient; the Si content and the N content at the first position in the first semiconductor material layer 300 are correspondingly the same as the Si content and the N content at the second position in the third semiconductor material layer 800. The first semiconductor material layer 300 may include a plurality of first material layer sub-layers stacked along the first direction. The Si content of each first material layer sub-layer decreases layer by layer along the first direction and the N content increases layer by layer. The Si content and the N content within a single first material layer sub-layer are unchanged; the third semiconductor material layer 800 includes a plurality of third material layer sub-layers stacked along the first direction. The Si content of each third material layer sub-layer increases layer by layer along the first direction and the N content decreases layer by layer. The Si content and the N content within a single third material layer sub-layer are unchanged; each first material layer sub-layer is sequentially sorted along the first direction starting from the first sub-layer of the first material layer. The first sub-layer of the first material layer is the layer closest to the first diaphragm 210; each third material layer sub-layer is sequentially sorted along the second direction starting from the first sub-layer of the third material layer. The first sub-layer of the third material layer is the layer closest to the second diaphragm 220; the Si content and the N content of the first material layer sub-layer and the third material layer sub-layer with the same serial number are correspondingly the same; the thicknesses of the first material layer sub-layer and the third material layer sub-layer with the same serial number are correspondingly the same. The number of the first material layer sub-layers in the first semiconductor material layer 300 is the same as the number of the third material layer sub-layers in the third semiconductor material layer 800. Thus, it is beneficial to achieve the symmetric arrangement of the first support portion 510 and the third support portion 530.

[0104] In some embodiments, the process conditions of the first wet etching process are the same as those of the second wet etching process. Thus, it is beneficial to achieve the symmetric arrangement of the first support portion 510 and the third support portion 530.

[0105] The material of the second sacrificial layer 620 may include silicon oxide. Of course, the present application does not exclude the case where the material of the second sacrificial layer 620 is other materials, and this embodiment does not limit this.

[0106] Optionally, please refer to Figure 1 , the second diaphragm 220 includes a second movable region 221 and a second fixed region 222 located on the outer periphery of the second movable region 221; by performing the second wet etching process on the third semiconductor material layer 800, a second convex structure 810 is further formed. The second convex structure 810 is located on the side of the second diaphragm 220 facing the back plate 700 and is connected to the second movable region 221. The cross-sectional area of the second convex structure 810 increases along the first direction; wherein, in the first direction, the projection of the second convex structure 810 falls within the projection range of the back plate 700.

[0107] Understandably, the second protrusion structure 810 and the third support portion 530 are formed based on the same material layer in the same process, which can save processes and costs. It should be noted that for the specific structure of the second protrusion structure 810, reference can be made to the description of the third support portion 530 and Figure 3 which will not be elaborated here.

[0108] The second protrusion structure 810 is formed on the second movable region 221 of the second diaphragm 220, substantially increasing the thickness of the second movable region 221 of the second diaphragm 220, thereby increasing the strength of the second diaphragm 220 and reducing the risk of permanent deformation due to insufficient diaphragm strength; the projection of the second protrusion structure 810 falls within the projection range of the back plate 700. When the second diaphragm 220 moves towards the back plate 700, the second protrusion structure 810 contacts the back plate 700 instead of the second diaphragm 220. The second protrusion structure 810 can serve as an anti-sticking structure to prevent the diaphragm from sticking to the back plate 700 during vibration, reducing the risk of device failure; moreover, the cross-sectional area of the second protrusion structure 810 increases along the first direction. While ensuring the strengthening effect of the second protrusion structure 810 on the strength of the second diaphragm 220, the contact area between the second protrusion structure 810 and the back plate 700 is reduced, thereby shortening the contact time between the second protrusion structure 810 and the back plate 700. After the second protrusion structure 810 contacts the back plate 700, the second diaphragm 220 can bounce away from the back plate 700 faster, reducing the risk of permanent deformation of the second diaphragm 220 due to a long contact state retention time.

[0109] Optionally, please refer to Figure 13 , before forming the second diaphragm 220 on the third support portion 530, the above method may further include: forming a third sacrificial layer 630 covering the sidewall of the third support portion 530 and the second sacrificial layer 620. The top surface of the third sacrificial layer 630 and the top end of the third support portion 530 form a flat plane. The top surface of the third sacrificial layer 630 is the surface of the third sacrificial layer 630 away from the second sacrificial layer 620, and the top end of the third support portion 530 is the end of the third support portion 530 away from the second sacrificial layer 620; the second diaphragm 220 covers the third sacrificial layer 630 and the third support portion 530. Thus, by forming the third sacrificial layer 630, the top surface of the third sacrificial layer 630 and the top end of the third support portion 530 form a flat plane, enabling the second diaphragm 220 to be fabricated on the flat plane, ensuring the flatness of the second diaphragm 220, and facilitating the improvement of the reliability of the MEMS device.

[0110] Understandably, during actual preparation, a third sacrificial material layer covering the third support portion 530 and the second sacrificial layer 620 can be first formed; then a planarization process is performed on the third sacrificial material layer to make the top surface of the third sacrificial layer 630 and the top end of the third support portion 530 form a flat plane.

[0111] The material of the third sacrificial layer 630 can include silicon oxide. Of course, this application does not exclude the case where the material of the third sacrificial layer 630 is other materials, and this embodiment does not limit this.

[0112] In some embodiments, when performing a second wet etching process on the third semiconductor material layer 800, a second reinforcing structure 910 is further formed on the side of the second diaphragm 220 facing the back plate 700, and the cross-sectional area of the second reinforcing structure 910 increases along the first direction; please refer to Figure 1 , in subsequent steps, specifically after forming the back plate 700 on the first sacrificial layer 610, the above method further includes: removing a part of the second sacrificial layer 620 and the third sacrificial layer 630, and the remaining second sacrificial layer 620 and third sacrificial layer 630 are formed into a second support structure 621 located on the second fixed area 222, and a part of the second reinforcing structure 910 is embedded in the second support structure 621. Thus, by providing the second support structure 621 on the second diaphragm 220, the thickness of the second diaphragm 220 is further increased, and the strength of the second diaphragm 220 is enhanced; the second reinforcing structure 910 and the third support portion 530 are formed based on the same material layer in the same process, saving processes and costs. It should be noted that for the specific structure of the second reinforcing structure 910, reference can specifically be made to the description of the third support portion 530 and Figure 3 is not elaborated here.

[0113] In some embodiments, the surface layer of the first semiconductor material layer 300 on the side away from the first diaphragm 210 includes a first reserved area and a first etched area. The first reserved area is used to form at least one of the following: the top of the first convex structure 310, the top of the first strengthening structure 410, and the top of the first supporting portion 510. The top of the first convex structure 310 is the end of the first convex structure 310 away from the first diaphragm 210. The top of the first strengthening structure 410 is the end of the first strengthening structure 410 away from the first diaphragm 210. The top of the first supporting portion 510 is the end of the first supporting portion 510 away from the first diaphragm 210. Before performing the first wet etching process on the first semiconductor material layer 300, the preparation method further includes: forming a first mask layer on the first semiconductor material layer 300. The first mask layer includes a first shielding portion and a first opening portion. The first opening portion exposes the first etched area. In the first direction, the projection of the first shielding portion covers the projection of the first reserved area, and the projection area of the first shielding portion is larger than the projection area of the first reserved area. It can be understood that wet etching is isotropic etching, and the etchant will etch the side of the material layer. Therefore, setting the size of the first shielding portion to be larger than the size of the first reserved area leaves room for the process, making the sizes of the finally prepared first convex structure 310, first strengthening structure 410, or first supporting portion 510 more accurate.

[0114] In some embodiments, the surface layer of the third semiconductor material layer 800 on the side away from the second sacrificial layer 620 includes a second reserved area and a second etched area. The second reserved area is used to form at least one of the following: the top of the second convex structure 810, the top of the second strengthening structure 910, and the top of the third supporting portion 530. The top of the second convex structure 810 is the end of the second convex structure 810 away from the second sacrificial layer 620. The top of the second strengthening structure 910 is the end of the second strengthening structure 910 away from the second sacrificial layer 620. The top of the third supporting portion 530 is the end of the third supporting portion 530 away from the second sacrificial layer 620. Before performing the second wet etching process on the third semiconductor material layer 800, the preparation method further includes: forming a second mask layer on the third semiconductor material layer 800. The second mask layer includes a second shielding portion and a second opening portion. The second opening portion exposes the second etched area. In the first direction, the projection of the second shielding portion covers the projection of the second reserved area, and the projection area of the second shielding portion is larger than the projection area of the second reserved area. It can be understood that wet etching is isotropic etching, and the etchant will etch the side of the material layer. Therefore, setting the size of the second shielding portion to be larger than the size of the second reserved area leaves room for the process, making the sizes of the finally prepared second convex structure 810, second strengthening structure 910, or third supporting portion 530 more accurate.

[0115] The process of forming the first mask layer may include a first photolithography process, and the process of forming the second mask layer may include a second photolithography process.

[0116] In some embodiments, the mask plates in the first lithography process and the second lithography process have the same shape. Further, the mask plates in the first lithography process and the second lithography process are the same mask plate. Specifically, when performing the first lithography process, the mask plate in the second lithography process is used as the mask plate. This can save the preparation of the mask plate and save processes and costs.

[0117] Next, please refer to Figure 15 , and form a back cavity 103 penetrating the substrate 100 from the second surface 102 side.

[0118] Then, please refer to Figure 1 , etch away part of the fourth sacrificial layer 640 to form a third cavity 603, and the remaining fourth sacrificial layer 640 is formed into a third support structure 641 located on the first fixed area 212; etch away part of the first sacrificial layer 610 to form a first cavity 601, and the remaining first sacrificial layer 610 is formed into a first support structure 611 located on the first fixed area 212; etch away part of the second sacrificial layer 620 and the third sacrificial layer 630 to form a second cavity 602, and the remaining second sacrificial layer 620 and third sacrificial layer 630 are formed into a second support structure 621 located on the second fixed area 222.

[0119] It should be noted that the MEMS device embodiments provided in this application and the MEMS device manufacturing method embodiments belong to the same concept; among the technical features in the technical solutions recorded in each embodiment, they can be arbitrarily combined without conflict. However, it should be further noted that for the MEMS device provided in the embodiments of this application, the combination of its technical features can already solve the technical problems to be solved in this application; therefore, the MEMS device provided in the embodiments of this application can be independent of the MEMS device manufacturing method provided in the embodiments of this application, and any MEMS device prepared by a manufacturing method that can form the MEMS device structure provided in the embodiments of this application is within the protection scope of this application.

[0120] It should be understood that the above embodiments are all exemplary and do not cover all possible implementation manners. Without departing from the scope of the present disclosure, various deformations and changes can be made based on the above embodiments. Similarly, the technical features of the above embodiments can be arbitrarily combined to form other embodiments of this application that may not be clearly described. Therefore, the above embodiments only represent several implementation manners of this application and do not limit the protection scope of the patent of this application.

Claims

1. A MEMS device, characterized in that, Comprising: A substrate, including a first surface and a second surface opposite to each other; A first diaphragm, located on the first surface side, the first diaphragm including a first movable region and a first fixed region located on the outer periphery of the first movable region; A first convex structure, located on the side of the first diaphragm away from the substrate and connected to the first movable region, the cross-sectional area of the first convex structure decreasing along a first direction, the cross-section being a plane parallel to the first surface, the first direction being the direction from the second surface to the first surface; the material of the first convex structure includes SiN, and along the first direction, the Si content in the first convex structure decreases and the N content increases; A first support structure, located on the side of the first diaphragm away from the substrate and connected to the first fixed region; A back plate, located on the side of the first support structure away from the first diaphragm; wherein, in the first direction, the projection of the first convex structure falls within the projection range of the back plate.

2. The MEMS device according to claim 1, wherein Further comprising: A first strengthening structure, located on the side of the first diaphragm away from the substrate, the cross-sectional area of the first strengthening structure decreasing along the first direction, and the first strengthening structure and the first convex structure being formed based on the same material layer in the same process; Part of the first strengthening structure is embedded in the first support structure.

3. The MEMS device according to claim 2, wherein In the same plane, the cross-sectional area of the first strengthening structure is larger than the cross-sectional area of the first convex structure.

4. The MEMS device according to claim 1, characterized in that, Further comprising: A second diaphragm, located on the side of the back plate away from the first diaphragm; A second support structure, located between the back plate and the second diaphragm to space the second diaphragm from the back plate; A through hole, penetrating the back plate along the first direction; A support column, including a first support portion connected to the first diaphragm, a third support portion connected to the second diaphragm, and a second support portion connected between the first support portion and the third support portion along the first direction; the cross-sectional area of the first support portion decreases along the first direction; the cross-sectional area of the third support portion increases along the first direction; The second support portion passes through the through hole; the cross-sectional areas of the first support portion and the third support portion are both larger than the cross-sectional area of the second support portion; The first support portion and the first convex structure are formed based on the same material layer in the same process; The material of the third support portion includes SiN, and along the first direction, the Si content in the third support portion increases and the N content decreases.

5. The MEMS device according to claim 4, wherein The second diaphragm includes a second movable region and a second fixed region located on the outer periphery of the second movable region; The MEMS device further includes: a second convex structure, located on the side of the second diaphragm facing the back plate and connected to the second movable region, the cross-sectional area of the second convex structure increasing along the first direction; wherein, in the first direction, the projection of the second convex structure falls within the projection range of the back plate; The second convex structure and the third support part are formed based on the same material layer in the same process.

6. A method for fabricating a MEMS device, characterized in that, The method includes: providing a substrate including a first surface and a second surface opposite to each other; forming a first diaphragm on the first surface side, the first diaphragm including a first movable region and a first fixed region located on the outer periphery of the first movable region; forming a first semiconductor material layer on the first diaphragm, the material of the first semiconductor material layer including SiN, the Si content in the first semiconductor material layer decreasing and the N content increasing along a first direction, the first direction being the direction from the second surface to the first surface; performing a first wet etching process on the first semiconductor material layer to form a first convex structure on the first movable region, the cross-sectional area of the first convex structure decreasing along the first direction, the cross-section being a plane parallel to the first surface; forming a first sacrificial layer covering the first diaphragm and the first convex structure; forming a back plate on the first sacrificial layer; wherein, in the first direction, the projection of the first convex structure falls within the projection range of the back plate.

7. The method for manufacturing a MEMS device according to claim 6, characterized in that when performing the first wet etching process on the first semiconductor material layer, a first strengthening structure is further formed, the first strengthening structure being located on the side of the first diaphragm away from the substrate and connected to the first fixed region, the cross-sectional area of the first strengthening structure decreasing along the first direction; after forming the back plate on the first sacrificial layer, the method further includes: removing part of the first sacrificial layer, and the remaining first sacrificial layer is formed into a first support structure located on the first fixed region, and part of the first strengthening structure is embedded in the first support structure.

8. The method for manufacturing a MEMS device according to claim 7, characterized in that in the same plane, the cross-sectional area of the first strengthening structure is larger than the cross-sectional area of the first convex structure.

9. The method for manufacturing a MEMS device according to claim 6, characterized in that when performing the first wet etching process on the first semiconductor material layer, a first support part is further formed, the cross-sectional area of the first support part decreasing along the first direction; a through hole penetrating the back plate along the first direction is formed in the back plate; after forming the back plate on the first sacrificial layer, the method further includes: forming a second sacrificial layer covering the back plate and filling the through hole; forming a through hole penetrating the second sacrificial layer and the first sacrificial layer and passing through the through hole, the through hole exposing the first support part; filling the through hole with a second semiconductor material layer to form a second support part; forming a third semiconductor material layer covering the second sacrificial layer and the second support part, the material of the third semiconductor material layer including SiN, the Si content in the third semiconductor material layer increasing and the N content decreasing along the first direction; Perform a second wet etching process on the third semiconductor material layer to form a third support portion, the cross-sectional area of the third support portion increasing along the first direction; the first support portion, the second support portion, and the third support portion are sequentially connected to form a support column, wherein the cross-sectional areas of the first support portion and the third support portion are both larger than the cross-sectional area of the second support portion; Form a second vibrating membrane on the third support portion.

10. The manufacturing method of the MEMS device according to claim 9, characterized in that, The second vibrating membrane includes a second movable region and a second fixed region located on the outer periphery of the second movable region; Performing the second wet etching process on the third semiconductor material layer further forms a second convex structure, the second convex structure being located on the side of the second vibrating membrane facing the back plate and connected to the second movable region, the cross-sectional area of the second convex structure increasing along the first direction; wherein, in the first direction, the projection of the second convex structure falls within the projection range of the back plate.

11. The manufacturing method of the MEMS device according to claim 9, characterized in that, Before forming the second vibrating membrane on the third support portion, the method further includes: forming a third sacrificial layer covering the side wall of the third support portion and the second sacrificial layer, the top surface of the third sacrificial layer and the top end of the third support portion forming a flat plane, the top surface of the third sacrificial layer being the surface of the third sacrificial layer away from the second sacrificial layer, and the top end of the third support portion being the end of the third support portion away from the second sacrificial layer; The second vibrating membrane covers the third sacrificial layer and the third support portion.

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