CN120246920B

CN120246920B - MEMS device and preparation method thereof

Info

Publication number: CN120246920B
Application number: CN202510735452.2A
Authority: CN
Inventors: 鲁列微
Original assignee: Xinlian Integrated Circuit Manufacturing Co ltd
Current assignee: Xinlian Integrated Circuit Manufacturing Co ltd
Priority date: 2025-06-04
Filing date: 2025-06-04
Publication date: 2025-08-29
Anticipated expiration: 2045-06-04
Also published as: CN120246920A

Abstract

The application relates to a preparation method of an MEMS device and the MEMS device, which comprise a substrate, a first vibrating diaphragm, a first bulge structure, a back plate and a second support structure, wherein the substrate comprises a first surface and a second surface which are opposite to each other, the first vibrating diaphragm is located on the side of the first surface and comprises a first movable area and a first fixed area, the first bulge structure is located on one side of the first vibrating diaphragm, which is far away from the substrate, and is connected with the first movable area, the cross section area of the first bulge structure is reduced along a first direction, the cross section is parallel to a plane of the first surface, the first direction is the direction from the second surface to the first surface, the material of the first bulge structure comprises SiN, the Si content in the first bulge structure is reduced and the N content in the first bulge structure is increased along the first direction, the first support structure is located on one side of the first vibrating diaphragm, which is far away from the substrate, the back plate is located on one side of the first support structure, the projection of the first bulge structure falls into the projection range of the back plate, and the reliability of the device is improved.

Description

MEMS device and preparation method thereof

Technical Field

The application relates to the technical field of semiconductors, in particular to a preparation method of an MEMS device and the MEMS device.

Background

With the rapid development of electronic technology, micro-Electro-MECHANICAL SYSTEM, MEMS (Micro-Electro-MECHANICAL SYSTEM, MEMS) devices have been increasingly used in terms of their small size, easy installation, high temperature resistance, good stability, high automation degree, suitability for mass production, and the like. Among the MEMS devices, the MEMS microphone, the MEMS pressure sensor and the like realize the device function by using the capacitor formed by the diaphragm and the back plate, specifically, the vibration of the diaphragm changes the distance between the diaphragm and the back plate, so that the capacitance of the capacitor changes, and the capacitance change can be amplified and converted into an electrical signal to be output, thereby realizing the device function.

The deformation of the vibrating diaphragm during vibration is usually temporary and recoverable, but in the actual preparation process, the vibrating diaphragm can also undergo subsequent multi-channel high-temperature processes after being formed, the strength of the vibrating diaphragm is weakened, and then the vibrating diaphragm can be permanently deformed during the vibration process, so that the capacitor formed by the vibrating diaphragm and the back electrode plate is changed, and the reliability of the device is reduced.

Disclosure of Invention

In view of the above, an embodiment of the present application provides a method for manufacturing a MEMS device and a MEMS device for solving at least one of the problems in the background art.

In a first aspect, an embodiment of the present application provides a MEMS device, including:

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 at an outer periphery of the first movable region;

A first bump structure located on a side of the first diaphragm away from the substrate and connected to the first movable region, the cross-sectional area of the first bump structure decreasing along a first direction, the cross-section being a plane parallel to the first surface, the first direction being a direction from the second surface to the first surface;

the first supporting structure is positioned on one side of the first vibrating diaphragm away from the substrate and is connected to the first fixing area;

and the back electrode plate is positioned on one side of the first supporting structure, which is far away from the first vibrating diaphragm, wherein in the first direction, the projection of the first bulge structure falls into the projection range of the back electrode plate.

With reference to the first aspect of the present application, in an optional implementation manner, the method further includes:

A first reinforcing structure located at a side of the first diaphragm away from the substrate, the cross-sectional area of the first reinforcing structure decreasing along the first direction, the first reinforcing structure and the first bump structure being formed based on the same material layer in the same process;

a portion of the first reinforcing structure is embedded within the first support structure.

In combination with the first aspect of the present application, in an alternative embodiment, the cross-sectional area of the first reinforcing structure is larger than the cross-sectional area of the first protruding structure in the same plane.

the second vibrating diaphragm is positioned at one side of the back electrode plate, which is far away from the first vibrating diaphragm;

The second support structure is positioned between the back electrode plate and the second vibrating diaphragm so as to enable the second vibrating diaphragm and the back electrode plate to be arranged at intervals;

a through opening penetrating the back plate along the first direction;

the support column comprises a first support part connected to the first vibrating diaphragm, a third support part connected to the second vibrating diaphragm and a second support part connected between the first support part and the third support part along the first direction, wherein the cross-sectional area of the first support part is reduced along the first direction, the cross-sectional area of the third support part is increased along the first direction, the second support part passes through the through hole, and the cross-sectional area of the first support part and the cross-sectional area of the third support part are both larger than the cross-sectional area of the second support part;

the first supporting portion and the first bump structure are formed based on the same material layer in the same process;

the material of the third support portion includes SiN, and Si content in the third support portion increases and N content decreases along the first direction.

With reference to 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 at an outer periphery of the second movable area;

The MEMS device further comprises a second bulge structure, a first bulge and a second bulge, wherein the second bulge structure is positioned on one side of the second vibrating diaphragm, which is towards the back electrode plate, and is connected to the second movable area, and the cross section area of the second bulge structure is increased along the first direction;

the second bump structure and the third supporting portion are formed based on the same material layer in the same process.

In a second aspect, an embodiment of the present application provides a method for preparing a MEMS device, where the method includes:

Providing a substrate comprising a first surface and a second surface opposite to each other;

forming a first diaphragm on the first surface side, wherein the first diaphragm comprises a first movable area and a fixed area positioned at the periphery of the first movable area;

Forming a first semiconductor material layer on the first vibrating film, wherein the material of the first semiconductor material layer comprises SiN, the Si content in the first semiconductor material layer is reduced and the N content is increased 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 bump structure on the first movable region, a cross-sectional area of the first bump 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 bump structure;

and forming a back electrode plate on the first sacrificial layer, wherein in the first direction, the projection of the first bulge structure falls into the projection range of the back electrode plate.

In combination with the second aspect of the application, in an alternative embodiment,

The first wet etching process is performed on the first semiconductor material layer, and a first reinforcing structure is formed, the first reinforcing structure is located on one side, away from the substrate, of the first vibrating diaphragm and is connected to the first fixing area, and the cross-sectional area of the first reinforcing structure is reduced along the first direction;

After the back electrode plate is formed on the first sacrificial layer, the method further comprises the steps of removing part of the first sacrificial layer, forming the rest of the first sacrificial layer into a first supporting structure located on the first fixing area, and embedding part of the first reinforcing structure into the first supporting structure.

In the same plane, the cross-sectional area of the first reinforcing structure is larger than the cross-sectional area of the first protruding structure.

The first wet etching process is performed on the first semiconductor material layer, and a first supporting portion is formed, wherein the cross-sectional area of the first supporting portion is reduced along the first direction;

a through hole penetrating through the back plate along a first direction is formed in the back plate;

After the forming the back electrode plate on the first sacrificial layer, the method further comprises:

forming a second sacrificial layer which covers the back electrode plate and fills the through hole;

forming a through hole penetrating through the second sacrificial layer and the first sacrificial layer and penetrating through the through hole, wherein the through hole exposes the first supporting part;

Filling a second semiconductor material layer in the through hole to form a second supporting part;

forming a third semiconductor material layer covering the second sacrificial layer and the second support portion, 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;

the first support part, the second support part and the third support part are sequentially connected to form a support column, wherein the cross-sectional area of the first support part and the cross-sectional area of the third support part are larger than the cross-sectional area of the second support part;

And forming a second vibrating diaphragm on the third supporting part.

With reference to the second aspect of the present application, in an alternative embodiment, the second diaphragm includes a second movable area and a second fixed area located at an outer periphery of the second movable area;

And performing a second wet etching process on the third semiconductor material layer to form a second protruding structure, wherein the second protruding structure is positioned on one side of the second vibrating diaphragm, which is towards the back electrode plate, and is connected to the second movable region, and the cross-sectional area of the second protruding structure is increased along the first direction, and the projection of the second protruding structure falls into the projection range of the back electrode plate in the first direction.

With reference to the second aspect of the present application, in an alternative embodiment, before the forming of the second diaphragm on the third supporting portion, the method further includes forming a third sacrificial layer covering the sidewall of the third supporting portion and the second sacrificial layer, wherein a top surface of the third sacrificial layer and a top end of the third supporting 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 supporting portion is an end of the third supporting portion away from the second sacrificial layer;

the second diaphragm covers the third sacrificial layer and the third supporting portion.

Compared with the prior art, the embodiment of the application has the following beneficial effects:

The MEMS device comprises a substrate, a first vibrating diaphragm, a first protruding structure, a back electrode plate and a first supporting structure, wherein the substrate comprises a first surface and a second surface which are opposite to each other, the first vibrating diaphragm is located on the side of the first surface, the first vibrating diaphragm comprises a first movable area and a first fixed area located on the periphery of the first movable area, the first protruding structure is located on one side, away from the substrate, of the first vibrating diaphragm and connected to the first movable area, the cross section area of the first protruding structure is reduced along a first direction, the cross section is a plane parallel to the first surface, the first direction is the direction from the second surface to the first surface, the material of the first protruding structure comprises SiN, the Si content in the first protruding structure is reduced and the N content is increased along the first direction, the first supporting structure is located on one side, away from the substrate, of the first vibrating diaphragm is connected to the first fixed area, the back electrode plate is located on one side, away from the first supporting structure, and the projection of the first protruding structure falls into the projection range of the back electrode plate in the first direction. The first bulge structure can be used as an anti-adhesion structure, adhesion to the back plate during vibration of the diaphragm is avoided, the risk of failure of a device is reduced, the cross section area of the first bulge structure is reduced along a first direction, the reinforcing effect of the first bulge structure on the strength of the first diaphragm is ensured, the contact area of the first bulge structure and the back plate is reduced, the contact time of the first bulge structure and the back plate is shortened, after the first bulge structure is in contact with the back plate, the first bulge structure can be sprung open towards the direction far away from the back plate more quickly, the risk of permanent deformation of the first diaphragm is reduced, in addition, the material of the first bulge structure comprises SiN, the content in the first bulge structure is reduced and the content of N is increased along the first direction, the cross section area of the first bulge structure is reduced, the etching material is more easily removed along the first direction, the cross section area of the first bulge structure is more easily removed along the first direction, the etching accuracy is further improved, the cross section area of the etching material is more easily removed along the first direction, and the etching accuracy is further improved, and the size of the first bulge structure is further increased along the first direction, the etching accuracy is further improved, and the cross section area of the first bulge structure is more removed along the direction of the etching material is more, and the etching the first bulge structure is more in the contact with the direction.

The MEMS device manufacturing method comprises the steps of providing a substrate, forming a first vibrating diaphragm on the side of the first surface, forming a first semiconductor material layer on the first vibrating diaphragm, forming a first sacrificial layer, and forming a back plate on the first sacrificial layer, wherein the first surface is in a direction from the second surface to the first surface, the first surface is opposite to the first surface, the cross section area of the first protruding structure is reduced along the first direction, the cross section of the first protruding structure is parallel to the plane of the first surface, the first sacrificial layer covers the first vibrating diaphragm and the first protruding structure, the back plate is formed on the first sacrificial layer, the first protruding structure is projected in the projection range of the back plate, and the first protruding structure is projected in the first direction. The method comprises the steps of forming a first bulge structure on a movable area of a first vibrating diaphragm, increasing the thickness and strength of the movable area of the first vibrating diaphragm, reducing the risk of permanent deformation caused by insufficient strength of the vibrating diaphragm, enabling the projection of the first bulge structure to fall into the projection range of a back plate, serving as an anti-adhesion structure, avoiding adhesion to the back plate when the vibrating diaphragm vibrates, reducing the risk of device failure, enabling the cross section area of the first bulge structure to be reduced along a first direction, guaranteeing the reinforcing effect of the first bulge structure on the strength of the first vibrating diaphragm, reducing the contact area of the first bulge structure and the back plate, reducing the contact time of the first bulge structure and the back plate, enabling the first bulge structure to be sprung open in a direction away from the back plate more quickly after the first bulge structure is contacted with the back plate, reducing the risk of permanent deformation of the first vibrating diaphragm when the contact state is kept for a long time, enabling the cross section area of the first bulge structure to be etched more easily to be removed when the first bulge structure is more away from the first semiconductor material layer along the first direction, enabling the cross section area of the first bulge structure to be etched more easily to be removed along the first direction, enabling the first bulge structure to be more high in accuracy, enabling the cross section area to be etched more excellent in the first direction, and enabling the size to be manufactured to be more high in the shape.

Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

FIG. 1 is a schematic cross-sectional view of a MEMS device according to an embodiment of the present application;

FIG. 2 is a schematic cross-sectional view of a first bump structure, a first reinforcing structure, and a first supporting portion according to a specific example;

FIG. 3 is a schematic cross-sectional view of a second bump structure, a second reinforcing structure, and a third supporting portion according to a specific example;

FIG. 4 is a schematic flow chart of a method for manufacturing a MEMS device according to an embodiment of the present application;

fig. 5 is a schematic cross-sectional view of a first semiconductor material layer according to an embodiment of the present application;

Fig. 6 is a schematic cross-sectional view of a first semiconductor material layer provided as a specific example;

FIG. 7 is a schematic cross-sectional view of a first protrusion structure, a first reinforcing structure and a first supporting portion according to an embodiment of the present application;

FIG. 8 is a schematic cross-sectional view of a back plate and a second sacrificial layer according to an embodiment of the present application;

FIG. 9 is a schematic cross-sectional view of a through hole according to an embodiment of the present application;

fig. 10 is a schematic cross-sectional view of a third semiconductor material layer according to an embodiment of the present application;

Fig. 11 is a schematic cross-sectional structure of a third semiconductor material layer provided as a specific example;

FIG. 12 is a schematic cross-sectional view of a second bump structure, a second reinforcing structure, and a third supporting portion according to an embodiment of the present application;

FIG. 13 is a schematic cross-sectional view of a third sacrificial layer according to an embodiment of the present application;

fig. 14 is a schematic cross-sectional structure of a second diaphragm according to an embodiment of the present application;

fig. 15 is a schematic cross-sectional structure of a back cavity according to an embodiment of the present application.

Reference numerals illustrate:

100. A substrate, 101, a first surface, 102, a second surface, 103, a 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. A first semiconductor material layer, 301, a first material layer first sub-layer, 302, a first material layer second sub-layer, 303, a first material layer third sub-layer;

310. a first bump structure;

410. a first reinforcing structure;

500. Support column, 510, first support part, 520, second support part, 530, third support part;

610. First sacrificial layer 611, first supporting structure 620, second sacrificial layer 621, second supporting structure 630, third sacrificial layer 640, fourth sacrificial layer 641, third supporting structure 601, first cavity 602, second cavity 603, third cavity 604, through hole;

700. back electrode plate, 710, first back electrode insulating layer, 720, back electrode conductive layer, 730, second back electrode insulating layer, 701, through hole;

800. Third semiconductor material layer, 801, third material layer first sub-layer, 802, third material layer second sub-layer, 803, third material layer third sub-layer;

810. a second bump structure;

910. And a second reinforcing structure.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the application are shown in the drawings, it should be understood that the application may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the application may be practiced without one or more of these details. In other instances, well-known functions and constructions are not described in detail since they would obscure the application in some of the features that are well known in the art, i.e., not all features of an actual embodiment are described herein.

In the drawings, the size of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like numbers refer to like elements throughout.

When an element or layer is referred to as being "on," "adjacent," "connected to," or "coupled to" another element or layer, it can be directly on, adjacent, 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 present. Although the terms first, second, third, etc. may be used herein 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 could be termed a second element, component, region, layer or section without departing from the teachings of the present application. When a second element, component, region, layer or section is discussed, it does not necessarily mean that the first element, component, region, layer or section is present.

Spatial relationship terms such as "under", "above", "over" and the like may be used herein for convenience of description to describe one element or feature as illustrated in the figures in relation to another element or feature. In addition to the orientations shown in the drawings, the spatially relative terms are intended to encompass different orientations of the device in use and operation. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "under" and "under" may include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.

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

In order to provide a thorough understanding of the present application, detailed steps and detailed structures will be presented in the following description in order to explain the technical solution of the present application. Preferred embodiments of the present application are described in detail below, however, the present application may have other embodiments in addition to these detailed descriptions.

FIG. 1 is a cross-sectional structure diagram of a MEMS device according to an embodiment of the present application, as shown in the figure, the MEMS device includes:

a substrate 100 comprising a first surface 101 and a second surface 102 opposite to each other;

A first diaphragm 210 located on the first surface 101 side, the first diaphragm 210 including a first movable region 211 and a first fixed region 212 located at an outer periphery of the first movable region 211;

The first bump structure 310 is located on one side of the first diaphragm 210 away from the substrate 100 and connected to the first movable region 211, and the cross-sectional area of the first bump structure 310 is reduced along a first direction, the cross-section is a plane parallel to the first surface 101, and the first direction is a direction from the second surface 102 to the first surface 101;

The first support structure 611 is located on a side of the first diaphragm 210 away from the substrate 100 and is connected to the first fixing area 212;

The back plate 700 is located on one side of the first support structure 611 away from the first diaphragm 210, where the projection of the first protrusion structure 310 falls within the projection range of the back plate 700 in the first direction.

Thereby, the reliability of the MEMS device is improved. Specifically, the first bump structure 310 is formed on the first movable region 211 of the first diaphragm 210, so that the thickness of the first diaphragm 210 is substantially increased, the strength of the first diaphragm 210 is increased, the risk of permanent deformation due to insufficient strength of the diaphragm is reduced, the first bump structure 310 is located in the first movable region 211 of the first diaphragm 210, the projection of the first bump structure 310 falls within the projection range of the backplate 700, when the first diaphragm 210 moves towards the backplate 700, the first bump structure 310 replaces the first diaphragm 210 to contact the backplate 700, the first bump structure 310 can serve as an anti-blocking structure, adhesion to the backplate 700 during vibration of the diaphragm is avoided, the risk of device failure is reduced, the cross-sectional area of the first bump structure 310 is reduced along the first direction, the contact area between the first bump structure 310 and the backplate 700 is reduced while the reinforcing effect of the strength of the first bump structure 310 on the first diaphragm 210 is ensured, the contact time between the first bump structure 310 and the backplate 700 is shortened, after the first bump structure 310 contacts the backplate 700, the first bump structure 310 contacts the backplate 210, the first bump structure 700 can keep the first diaphragm 700 in a long-term elastic deformation state after the first bump structure 210 contacts the backplate 700, and the first bump structure is kept away from the backplate 700, and the risk of permanent deformation is reduced in the first direction. In addition, since the material of the first bump structure 310 includes SiN, and the Si content in the first bump structure 310 decreases and the N content increases along the first direction, the portion of the material layer used to form the first bump structure 310 that is farther from the first diaphragm 210 is more easily etched away, so that the etching amount of the material layer by the etchant along the first direction increases during the preparation process, the remaining material layer forms the first bump structure 310 with a cross-sectional area decreasing along the first direction, the dimensional accuracy of the first bump structure 310 is higher, the contour uniformity is better, the strength is higher, and the process is simple.

In some embodiments, the MEMS device is a MEMS microphone. Of course the application does not exclude that the MEMS device is any other suitable device known to the person skilled in the art, in particular such as a pressure sensor.

The substrate 100 may be a silicon substrate, may include Ge, siGe, siC, siGeC, inAs, gaAs, inP, inGaAs or other compound semiconductors, may include a multilayer structure formed of these semiconductors, or the like, or the substrate 100 may be silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-germanium-on-insulator (S-SiGeOI), silicon-germanium-on-insulator (SiGeOI), germanium-on-insulator (GeOI), or the like, which may be selected by those skilled in the art as needed, and the present embodiment is not limited thereto.

Referring to fig. 1, a back cavity 103 penetrating the substrate 100 along a first direction is formed in the substrate 100.

In some embodiments, the MEMS device further comprises a third support structure 641 located on a side of the first diaphragm 210 facing the substrate 100 and connected to the first fixed region 212, and a third cavity 603, the third support structure 641 surrounding the third cavity 603. Thus, the first diaphragm 210 is spaced 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 a second direction, which is the direction from the first surface 101 to the second surface 102.

The material of the third support structure 641 may include silicon oxide. Of course, the present application does not exclude the case that the material of the third support structure 641 is other than the material, which is not limited in this embodiment.

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

The material of the first diaphragm 210 may include polysilicon. Of course, the present application does not exclude the case that the material of the first diaphragm 210 is other materials, which is not limited in this embodiment.

It may be appreciated that the first movable region 211 of the first diaphragm 210 is a portion of the first diaphragm 210 that can move in the first direction or the second direction, and the first fixing region 212 of the first diaphragm 210 is connected to the first support structure 611 and the third support structure 641, for fixing the first diaphragm 210, and is an immovable portion of the first diaphragm 210.

In some embodiments, the Si content in the first bump structure 310 decreases linearly and the N content increases linearly along the first direction. The first bump structure 310 has a trapezoid shape in longitudinal section, which is a plane parallel to the first direction. Optionally, the angle between the sidewall of the first protruding structure 310 and the bottom end of the first protruding structure 310 ranges from 30 ° to 60 °, and the bottom end of the first protruding structure 310 is the end of the first protruding structure 310 facing the first diaphragm 210. Controlling the inclination angle of the sidewalls of the first bump structures 310 within this range is more advantageous for stress conduction. Of course, the present application does not exclude the case that the angle between the sidewall of the first protruding structure 310 and the bottom end of the first protruding structure 310 is greater than 0 ° and less than 30 °.

In some embodiments, the Si content in the first bump structure 310 decreases and the N content increases in a gradient along the first direction. Optionally, the first bump 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 and the N content increases layer by layer along the first direction, and 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 bump structure 310 is stepped. As a specific example, referring to fig. 2, the first bump structure 310 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 sequentially along a first direction, wherein Si content in the first material layer first sub-layer 301 is X1 and N content is Y1, si content in the first material layer second sub-layer 302 is X2 and N content is Y2, si content in the first material layer third sub-layer 303 is X3 and N content is Y3, si content decreases and N content increases progressively from the first material layer first sub-layer 301 to the first material layer third sub-layer 303, specifically, X1> X2> X3, and Y1< Y2< Y3.

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

The material of the first support structure 611 may include silicon oxide. Of course, the present application does not exclude the case that the material of the first support structure 611 is other materials, which is not limited in this embodiment.

As shown in fig. 1, the MEMS device may further include a first cavity 601, with a first support structure 611 surrounding the first cavity 601. The first cavity 601 provides a space for the first diaphragm 210 to move in a first direction. The first cavity 601 communicates with the third cavity 603 through the first air hole 213.

Optionally, the MEMS device further comprises a first reinforcing structure 410 located on a side of the first diaphragm 210 remote from the substrate 100, the cross-sectional area of the first reinforcing structure 410 decreasing along the first direction, the first reinforcing structure 410 being formed based on the same material layer in the same process as the first bump structure 310, and a portion of the first reinforcing structure 410 being embedded in the first supporting structure 611.

Therefore, the first diaphragm 210 is further increased in thickness by providing the first reinforcing structure 410 on the first diaphragm 210, the strength of the first diaphragm 210 is enhanced, the stress concentration can be reduced by providing the first reinforcing structure 410 with a reduced cross-sectional area along the first direction, and the reliability is improved, and the first reinforcing structure 410 is partially embedded into the first supporting structure 611, so that the first reinforcing structure 410 can also serve as an anchoring structure, enhancing the connection strength between the second diaphragm 220 and the second supporting structure 621, and further contributing to enhancing the reliability of the device.

The first reinforcing structure 410 and the first bump structure 310 are formed based on the same material layer in the same process, saving the process and the cost. It should be noted that, regarding the specific structure of the first reinforcing structure 410, reference may be made to the description of the first protruding structure 310 and fig. 2, and the description thereof will not be repeated here.

Optionally, the cross-sectional area of the first reinforcing structure 410 is larger than the cross-sectional area of the first bump structure 310 in the same plane. It will be appreciated 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, so that the size of the first protrusion structure 310 is relatively small, the contact time can be reduced, and the risk of permanent deformation of the first diaphragm 210 is reduced, the first reinforcement structure 410 is located in the first fixing region 212, and the size of the first reinforcement structure 410 is set relatively large, which is more beneficial to reinforcing the thickness and strength of the first diaphragm 210, and thus, under the synergistic effect of the two, the strength and anti-adhesion effect of the first diaphragm 210 are synchronously reinforced, which is beneficial to improving the reliability of the device.

In some embodiments, the back plate 700 may include a first back electrode insulating layer 710, a back electrode conductive layer 720, and a second back electrode insulating layer 730 stacked sequentially along a first direction. The materials of the first and second back electrode insulating layers 710 and 730 may include silicon nitride, and the material of the back electrode conductive layer 720 may include polysilicon. Of course, the embodiment of the present application does not exclude the case that the materials of the first back electrode insulating layer 710, the back electrode conductive layer 720, and the second back electrode insulating layer 730 are other materials, and in addition, the materials of the first back electrode insulating layer 710 and the second back electrode insulating layer 730 may be different.

In some embodiments, the MEMS device further comprises:

The second diaphragm 220 is positioned on one 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, so that the second diaphragm 220 is spaced apart from the back plate 700;

a through hole 701 penetrating the back plate 700 in the first direction;

The support column 500 includes a first support part 510 connected to the first diaphragm 210, a third support part 530 connected to the second diaphragm 220, and a second support part 520 connected between the first support part 510 and the third support part 530 in a first direction, wherein a cross-sectional area of the first support part 510 decreases in the first direction, a cross-sectional area of the third support part 530 increases in the first direction, the second support part 520 passes through the through-hole 701, and a cross-sectional area of the first support part 510 and a cross-sectional area of the third support part 530 are both larger than a cross-sectional area of the second support part 520;

The first support 510 and the first bump structure 310 are formed based on the same material layer in the same process;

the material of the third support 530 includes SiN, and the Si content in the third support 530 increases and the N content decreases in the first direction.

It will be appreciated that the MEMS device has a first diaphragm 210 and a second diaphragm 220, which may be referred to as a "dual diaphragm MEMS device". The support column 500 is generally disposed between the two diaphragms of the dual-diaphragm MEMS device, and the support column 500 is generally in 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, the stress conduction effect of the support column 500 in the vertical structure is poor, stress concentration is easy to occur, and the reliability of the MEMS device is affected. In some related arts, through etching the first sacrificial layer for forming the first support structure 611 and the second sacrificial layer for forming the second support structure 621, through holes having a width at both ends larger than that of the middle portion are formed, and the support pillars 500 are formed by filling materials in the through holes, and although the support pillars 500 are formed to have a larger width at both ends, the support effect and stress conduction effect on the support pillars 500 are improved to some extent, voids may occur in the filled support pillars 500, the structural accuracy and strength are poor, and it is difficult to effectively improve the reliability of the device.

In the embodiment of the application, the Si content in the first supporting part 510 is reduced and the N content is increased along the first direction, the Si content in the third supporting part 530 is increased and the N content is reduced, the wet etching rate is changed, during actual preparation, the two ends of the supporting column 500, namely the first supporting part 510 and the third supporting part 530, can be directly obtained through etching a material layer, the structural accuracy of the supporting column 500 is better, the supporting strength is higher, the cross-sectional area of the first supporting part 510 and the cross-sectional area of the third supporting part 530 are both larger than the cross-sectional area of the second supporting part 520, the cross-sectional area of the first supporting part 510 is reduced along the first direction, the cross-sectional area of the third supporting part 530 is increased along the first direction, the contact surface area of the first supporting part 510 and the first vibrating diaphragm 210 is larger, the contact surface area of the third supporting part 530 and the second vibrating diaphragm 220 is larger, the stress conduction effect is better, the stress concentration is avoided, and the reliability of the device is improved.

The first support 510 and the first bump structure 310 are formed based on the same material layer in the same process. Thereby saving process and cost. It should be noted that, regarding the specific structure of the first supporting portion 510, reference may be made to the description of the first protruding structure 310 and fig. 2, and details thereof are not repeated herein.

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

In some embodiments, the Si content in the third support 530 increases and the N content decreases in a gradient along the first direction. Alternatively, the third support 530 includes a plurality of third material layer sub-layers stacked in 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 in the first direction, and the Si content and the N content in the single third material layer sub-layers are unchanged. The longitudinal sectional shape of the third supporting portion 530 is stepped. As a specific example, referring to fig. 3, the third supporting 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 order along the first direction, wherein Si content in the third material layer first sub-layer 801 is A1 and N content is B1, si content in the third material layer second sub-layer 802 is A2 and N content is B2, si content in the third material layer third sub-layer 803 is A3 and N content is B3, and Si content increases and N content decreases from the third material layer third sub-layer 803 to the third material layer first sub-layer 801, specifically, A1> A2> A3, and B1< B2< B3.

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

Optionally, the first supporting portion 510 and the third supporting portion 530 are symmetrically disposed along a plane where a center of the second supporting portion 520 is located, and the plane where the center of the second supporting portion 520 is located is parallel to the plane where the first surface 101 is located. From this, the both ends symmetry setting of support column 500, support column 500 stress conduction effect is better, and the supporting effect is higher, is favorable 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 and the projection of the cross section at the second position in the third support portion 530 completely overlap, 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 part 510 is the same as that of the third support part 530.

In some embodiments, the Si content in the first support 510 decreases linearly and the N content increases linearly in the first direction, the Si content in the third support 530 increases linearly and the N content decreases linearly, and the Si content and the N content at the first location in the first support 510 correspond to the same Si content and the N content at the second location in the third support 530. Thereby, it is advantageous to achieve a symmetrical arrangement of the first support 510 and the third support 530.

In some embodiments, the Si content in the first support 510 is graded and the N content is graded and the Si content in the third support 530 is graded and the N content is graded and the Si content and the N content at the first location in the first support 510 are correspondingly the same as the Si content and the N content at the second location in the third support 530. The first support part 510 may include a plurality of first material layer sub-layers stacked in a first direction, the Si content of each first material layer sub-layer decreases and the N content of each first material layer increases from layer to layer in the first direction, the Si content and the N content of each first material layer sub-layer are unchanged, the third support part 530 includes a plurality of third material layer sub-layers stacked in the first direction, the Si content of each third material layer sub-layer increases and the N content of each third material layer sub-layer decreases from layer to layer in the first direction, the Si content and the N content of each first material layer sub-layer are unchanged, each first material layer sub-layer is sequentially ordered from the first material layer sub-layer to the first material layer, the first material layer sub-layer is sequentially ordered from the first material layer sub-layer to the third material layer, the first material layer sub-layer is sequentially ordered from the first material layer to the third material layer, the third material layer sub-layer is adjacent to the second material layer 220, the Si content and the N content of each third material layer sub-layer is unchanged, the Si content and the N content of each first material layer sub-layer is sequentially ordered from the first material layer to the first material layer. The number of the first material layer sub-layers in the first supporting part 510 is the same as the number of the third material layer sub-layers in the third supporting part 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 numbers are completely overlapped. Thereby, it is advantageous to achieve a symmetrical arrangement of the first support 510 and the third support 530.

As a specific example, referring to fig. 2 and 3, the first support 510 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 a first direction, the third support 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 the first direction, si contents decrease from the first material layer first sub-layer 301 to the first material layer third sub-layer 303, and si contents increase from the third material layer first sub-layer 801 to the third material layer third sub-layer 803. The Si content and the N content of the first material layer first sub-layer 301 are correspondingly equal to those of the third material layer first sub-layer 801, the Si content and the N content of the first material layer second sub-layer 302 are correspondingly equal to those of the third material layer second sub-layer 802, and the Si content and the N content of the first material layer third sub-layer 303 are correspondingly equal to those of the third material layer third sub-layer 803. The thickness of the first material layer first sub-layer 301 is correspondingly equal to the thickness of the third material layer first sub-layer 801, the thickness of the first material layer second sub-layer 302 is correspondingly equal to the thickness of the third material layer second sub-layer 802, and the thickness of the first material layer third sub-layer 303 is correspondingly equal to the thickness of the third material layer third sub-layer 803. In the first direction, the projection of the first material layer first sub-layer 301 completely overlaps the projection of the third material layer first sub-layer 801, the projection of the first material layer second sub-layer 302 completely overlaps the projection of the third material layer second sub-layer 802, and the projection of the first material layer third sub-layer 303 completely overlaps the projection of the third material layer third sub-layer 803.

The material of the second support structure 621 may comprise silicon oxide. Of course, the present application does not exclude the case that the material of the second support structure 621 is other material, which is not limited in this embodiment.

Referring to fig. 1, the mems device further includes a second cavity 602, and a second support structure 621 surrounds the second cavity 602. The second cavity 602 provides room for the second diaphragm 220 to move in a second direction. The second cavity 602 communicates with the first cavity 601 through the through port 701.

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

The material of the second diaphragm 220 may include polysilicon. Of course, the present application does not exclude the case that the material of the second diaphragm 220 is other materials, which is not limited in this embodiment.

Alternatively, 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.

Alternatively, 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.

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

It will be appreciated that the second bump structure 810 is formed on the same material layer in the same process as the third supporting portion 530, which may save process and cost. It should be noted that, regarding the specific structure of the second protruding structure 810, reference may be made specifically to the description of the third supporting portion 530 and fig. 3, and a detailed description is omitted herein.

Thereby, the reliability of the MEMS device is improved. Specifically, the second bump structure 810 is formed on the second movable region 221 of the second diaphragm 220, so that the thickness of the second movable region 221 of the second diaphragm 220 is substantially increased, the strength of the second diaphragm 220 is increased, the risk of permanent deformation due to insufficient strength of the diaphragm is reduced, the projection of the second bump structure 810 falls within the projection range of the backplate 700, when the second diaphragm 220 moves towards the backplate 700, the second bump structure 810 replaces the second diaphragm 220 to contact the backplate 700, the second bump structure 810 can serve as an anti-adhesion structure, adhesion to the backplate 700 during vibration of the diaphragm is avoided, the risk of failure of a device is reduced, the cross-sectional area of the second bump structure 810 is increased along the first direction, the contact area of the second bump structure 810 with the backplate 700 is reduced while the reinforcing effect of the strength of the second bump structure 810 on the second diaphragm 220 is ensured, the contact time of the second bump structure 810 with the backplate 700 is shortened, after the second bump structure 810 contacts the backplate 700, the second bump structure 810 can rapidly contact the backplate 700, the second diaphragm 220 can be kept away from the backplate 700, and the risk of permanent deformation is reduced in the long-time.

It will be appreciated that in actual fabrication, the Si content of the material layer along the first direction may be controlled to increase and the N content may be controlled to decrease, so that the wet etching rate of the material layer decreases along the first direction, and thus, when the wet etching process is performed, the etching amount of the etchant to the material layer increases, and the remaining material layer forms the second bump structure 810 having a cross-sectional area that increases along the first direction, the dimensional accuracy of the second bump structure 810 is higher, the structural strength is higher, and the process is simple.

It may be appreciated that the second movable area 221 of the second diaphragm 220 is a portion of the second diaphragm 220 that can move in the first direction or the second direction, and the second fixing area 222 of the second diaphragm 220 is connected to the second support structure 621, for fixing the second diaphragm 220, which is an immovable portion of the second diaphragm 220.

Optionally, the MEMS device further comprises a second reinforcing structure 910 located on a side of the second diaphragm 220 facing the back plate 700, the cross-sectional area of the second reinforcing structure 910 increasing along the first direction, the second reinforcing structure 910 being formed based on the same material layer in the same process as the third support 530, and a portion of the second reinforcing structure 910 being embedded in the second support 621.

Thus, the second supporting structure 621 is arranged on the second diaphragm 220, so that the thickness of the second diaphragm 220 is further increased, the strength of the second diaphragm 220 is enhanced, the second reinforcing structure 910 and the third supporting portion 530 are formed on the basis of the same material layer in the same process, and the process and the cost are saved. It should be noted that, regarding the specific structure of the second reinforcing structure 910, reference may be made to the description of the third supporting portion 530 and fig. 3, and details thereof are not repeated herein.

Optionally, the cross-sectional area of the second reinforcing structure 910 is larger than the cross-sectional area of the second bump structure 810 in the same plane. It will be appreciated that the second protrusion structure 810 is located in the second movable area 221 and contacts the back plate 700 when the second diaphragm 220 moves, so that the size of the second protrusion structure 810 is relatively small, the contact area and time can be reduced, the risk of permanent deformation of the second diaphragm 220 is reduced, the second reinforcing structure 910 is located in the second fixing area 222, the size of the second reinforcing structure 910 is relatively large, the thickness and strength of the second diaphragm 220 are more favorably enhanced, and therefore, the strength and anti-adhesion effect of the second diaphragm 220 are synchronously enhanced under the synergistic effect of the two, and the reliability of the device is further improved.

The embodiment of the application also provides a preparation method of the MEMS device, referring to FIG. 4, the preparation method comprises the following steps:

step S101, providing a substrate, wherein the substrate comprises a first surface and a second surface which are opposite to each other;

step S102, forming a first vibrating diaphragm on the first surface side, wherein the first vibrating diaphragm comprises a first movable area and a fixed area positioned at the periphery of the first movable area;

Step S103, forming a first semiconductor material layer on the first vibrating diaphragm, wherein the material of the first semiconductor material layer comprises SiN, the Si content in the first semiconductor material layer is reduced and the N content is increased along a first direction, and the first direction is the direction from the second surface to the first surface;

step S104, performing a first wet etching process on the first semiconductor material layer to form a first protruding structure on the first movable region, wherein the cross-sectional area of the first protruding structure is reduced along a first direction, and the cross-section is a plane parallel to the first surface;

Step 105, forming a first sacrificial layer covering the first diaphragm and the first bump structure;

and S106, forming a back electrode plate on the first sacrificial layer, wherein in the first direction, the projection of the first bulge structure falls into the projection range of the back electrode plate.

The method comprises the steps of forming a first bulge structure on a first movable area of a first vibrating diaphragm, increasing the thickness and strength of the movable area of the first vibrating diaphragm, reducing the risk of permanent deformation caused by insufficient strength of the vibrating diaphragm, enabling the projection of the first bulge structure to fall into the projection range of a back plate, serving as an anti-adhesion structure, avoiding adhesion to the back plate when the vibrating diaphragm vibrates, reducing the risk of device failure, enabling the cross section area of the first bulge structure to be reduced along a first direction, guaranteeing the reinforcing effect of the first bulge structure on the strength of the first vibrating diaphragm, reducing the contact area of the first bulge structure and the back plate, reducing the contact time of the first bulge structure and the back plate, enabling the first vibrating diaphragm to be sprung open in a direction away from the back plate faster after the first bulge structure is contacted with the back plate, reducing the risk of permanent deformation caused by long retention time of the first vibrating diaphragm, and enabling the Si content in the first semiconductor material layer to be reduced and the N content to be increased in a specific way, enabling the cross section area of the first semiconductor material layer to be reduced along the first direction, enabling the cross section area of the first bulge structure to be more easily removed along the first direction, enabling the cross section area of the first bulge structure to be etched to be more easily removed along the first direction, enabling the bulge structure to be more uniform, and enabling the cross section area to be more high in the accuracy to be manufactured, and more high in the reliability, and enabling the final to be more etching to be more easily etched.

First, referring to fig. 5, step S101 is performed to provide a substrate 100, where the substrate 100 includes a first surface 101 and a second surface 102 opposite to each other.

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

Next, step S102 is performed, where a first diaphragm 210 is formed on the first surface 101 side, and the first diaphragm 210 includes a first movable region 211 and a first fixed region 212 located at the outer periphery of the first movable region 211.

In some embodiments, the method of making may further include forming first air holes 213 extending through the first diaphragm 210 in the first direction.

Next, step S103 is performed to form a first semiconductor material layer 300 on the first diaphragm 210, where the material of the first semiconductor material layer 300 includes SiN, and the Si content in the first semiconductor material layer 300 decreases and the N content increases along the first direction. Thus, by controlling the Si content and the N content in the first semiconductor material layer 300, the wet etching rate of the first semiconductor material layer 300 can be controlled in turn, and then a structure of a desired shape can be obtained when the wet etching process is performed subsequently.

In actual production, the variation of the Si content and the N content in the first semiconductor material layer 300 can be controlled by adjusting the Si source gas introduction amount and the N source gas introduction amount.

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

In some embodiments, the Si content in the first semiconductor material layer 300 decreases and the N content increases in a gradient along the first direction. Alternatively, the first semiconductor material layer 300 includes a plurality of first material layer sub-layers stacked in 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 in the first direction, and the Si content and the N content in the single first material layer sub-layers are unchanged. As a specific example, referring to fig. 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 order along a first direction, wherein Si content in the first material layer first sub-layer 301 is X1 and N content is Y1, si content in the first material layer second sub-layer 302 is X2 and N content is Y2, si content in the first material layer third sub-layer 303 is X3 and N content is Y3, si content decreases and N content increases progressively, specifically, X1> X2> X3, and Y1< Y2< Y3.

Next, referring to fig. 7, step S104 is performed to perform a first wet etching process on the first semiconductor material layer 300 to form a first bump structure 310 on the first movable region 211, wherein a cross-sectional area of the first bump structure 310 decreases along the first direction. By forming the first protrusion structure 310 in 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.

It will be appreciated that the higher the Si content and the lower the N content in the SiN layer, the easier it is to etch. Accordingly, the Si content in the first semiconductor material layer 300 decreases and the N content increases in the first direction, and during the first wet etching process, the etching amount of the etchant to the first semiconductor material layer 300 decreases in the first direction, and the remaining first semiconductor material layer 300 constitutes the first bump structure 310 having a cross-sectional area decreasing in the first direction.

The etchant may include hydrofluoric acid or phosphoric acid.

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

In some embodiments, referring to fig. 2 and 6, the first semiconductor material layer 300 includes a plurality of first material layer sub-layers stacked along a first direction, the Si content in the first material layer sub-layers decreases layer by layer and the N content increases layer by layer along the first direction, the Si content and the N content in the single first material layer sub-layers are unchanged, and the longitudinal cross-sectional shape of the first bump structure 310 is a step shape.

Optionally, referring to fig. 7, in performing step S104, a first wet etching process is performed on the first semiconductor material layer 300, and a first reinforcing structure 410 is further formed, where the first reinforcing structure 410 is located on a side of the first diaphragm 210 away from the substrate 100 and is connected to the first fixing region 212, and a cross-sectional area of the first reinforcing structure 410 decreases along a first direction, and referring to fig. 1, after forming the back plate 700 on the first sacrificial layer 610 in a subsequent step, the method may further include removing a portion of the first sacrificial layer 610, forming a remaining first sacrificial layer 610 into a first supporting structure 611 located on the first fixing region 212, and embedding a portion of the first reinforcing structure 410 into the first supporting structure 611.

Thus, the first reinforcing structure 410 and the first bump structure 310 are formed based on the same material layer in the same process, saving the process and cost. It should be noted that, regarding the specific structure of the first reinforcing structure 410, reference may be made to the description of the first protruding structure 310 and fig. 2, and a detailed description is omitted herein.

Optionally, the cross-sectional area of the first reinforcing structure 410 is larger than the cross-sectional area of the first bump structure 310 in the same plane.

It will be appreciated that the first protrusion structure 310 is located in the first movable region 211 and contacts the back plate 700 when the first diaphragm 210 moves, so that the size of the first protrusion structure 310 is relatively small, the contact time can be reduced, and the risk of permanent deformation of the first diaphragm 210 is reduced, the first reinforcement structure 410 is located in the first fixing region 212, and the size of the first reinforcement structure 410 is set relatively large, which is more beneficial to reinforcing the thickness and strength of the first diaphragm 210, and therefore, the strength and anti-adhesion effect of the first diaphragm 210 are synchronously reinforced under the synergistic effect of the two, which is beneficial to improving the reliability of the device.

Next, referring to fig. 8, step S105 is performed to form a first sacrificial layer 610 covering the first diaphragm 210 and the first bump structure 310.

The material of the first sacrificial layer 610 may include silicon oxide. Of course, the present application does not exclude the case that the material of the first sacrificial layer 610 is other materials, which is not limited in this embodiment.

Next, step S106 is performed to form a back plate 700 on the first sacrificial layer 610, wherein the projection of the first bump structure 310 falls within the projection range of the back plate 700 in the first direction. In addition, the cross section area of the first bump structure 310 is reduced along the first direction, the contact area between the first bump structure 310 and the back plate 700 is reduced while the strength reinforcing effect of the first bump structure 310 on the first diaphragm 210 is ensured, so that the contact time between the first bump structure 310 and the back plate 700 is shortened, after the first bump structure 310 contacts the back plate 700, the first diaphragm 210 can spring away from the back plate 700 more quickly, and the permanent deformation risk of the first diaphragm 210 in a contact state for a long time is reduced.

Alternatively, referring to fig. 1 and 7 to 14, in performing step S104, a first wet etching process is performed on the first semiconductor material layer 300, and a first support portion 510 is further formed, wherein a cross-sectional area of the first support portion 510 decreases along a first direction;

a through hole 701 penetrating the back plate 700 in the first direction is formed in the back plate 700;

After performing step S106 to form the back plate 700 on the first sacrificial layer 610, the method further includes:

Forming a second sacrificial layer 620 that covers the back plate 700 and fills the via 701;

Forming a through hole 604 penetrating the second sacrificial layer 620 and the first sacrificial layer 610 and penetrating the through hole 701, the through hole 604 exposing the first support portion 510;

filling the second semiconductor material layer in the through holes 604 to form second supporting parts 520;

Forming a third semiconductor material layer 800 covering the second sacrificial layer 620 and the second support 520, the material of the third semiconductor material layer 800 including SiN, the Si content in the third semiconductor material layer 800 increasing and the N content decreasing 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 area of the first support portion 510 and the cross-sectional area of the third support portion 530 are both larger than the cross-sectional area of the second support portion 520;

the second diaphragm 220 is formed on the third support 530.

According to the embodiment of the application, the Si content in the first semiconductor material layer 300 is reduced and the N content is increased along the first direction, the Si content in the third semiconductor material layer 800 is increased and the N content is reduced, and the wet etching rate is changed, so that two ends of the support column 500, namely the first support part 510 and the third support part 530, can be directly obtained through etching the material layer, the cross section area of the first support part 510 and the cross section area of the third support part 530 are both larger than the cross section area of the second support part 520, the structural accuracy of the support column 500 is better, the support strength is higher, the cross section area of the first support part 510 is reduced along the first direction, the cross section area of the third support part 530 is increased along the first direction, the contact surface area of the first support part 510 and the first diaphragm 210 is larger, the contact surface area of the third support part 530 and the second diaphragm 220 is larger, the stress conduction effect is better, and stress concentration is more beneficial to avoiding, and therefore, the reliability of the MEMS device is beneficial to be improved.

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 third support 530 has a trapezoidal longitudinal cross-sectional shape. Optionally, an angle between a side wall of the third supporting portion 530 and a top end of the third supporting portion 530 ranges from 30 ° to 60 °, and the top end of the third supporting portion 530 is an end of the third supporting portion 530 facing the second diaphragm 220. Of course, the present application does not exclude the case that the angle between the side wall of the third supporting portion 530 and the top end of the third supporting portion 530 is greater than 0 ° and less than 30 °.

In some embodiments, the Si content in the third semiconductor material layer 800 increases and the N content decreases in a gradient along the first direction. Alternatively, the third semiconductor material layer 800 may include a plurality of third material layer sub-layers stacked in the first direction, the Si content in the third material layer sub-layers increasing layer by layer and the N content decreasing layer by layer in the first direction, the Si content and the N content within a single third material layer sub-layer being unchanged. As a specific example, referring to fig. 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 order along the first direction, the Si content in the third material layer first sub-layer 801 is A1 and the N content is B1, the Si content in the third material layer second sub-layer 802 is A2 and the N content is B2, the Si content in the third material layer third sub-layer 803 is A3 and the N content is B3, and the Si content increases and the N content decreases from the third material layer third sub-layer 803 to the third material layer first sub-layer 801, specifically, A1> A2> A3, and B1< B2< B3. Referring to fig. 3, in the first direction, the cross-sectional shape of the third supporting portion 530 is stepped.

In some embodiments, the Si content in the first semiconductor material layer 300 linearly decreases and the N content linearly increases along the first direction, the Si content in the third semiconductor material layer 800 linearly increases and the N content linearly decreases, and the Si content and the N content at the first location in the first semiconductor material layer 300 correspond to the same Si content and the N content at the second location 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. Thereby, it is advantageous to achieve a symmetrical arrangement of the first support 510 and the third support 530.

In some embodiments, the Si content in the first semiconductor material layer 300 is graded and the N content is graded in a first direction, the Si content in the third semiconductor material layer 800 is graded and the N content is graded in a first direction, and the Si content and the N content at a first location in the first semiconductor material layer 300 are correspondingly the same as the Si content and the N content at a second location in the third semiconductor material layer 800. The first semiconductor material layer 300 may include a plurality of first material layer sub-layers stacked in a first direction, the Si content of each first material layer sub-layer decreases and the N content of each first material layer increases from layer to layer in the first direction, the Si content and the N content of each third material layer sub-layer are unchanged, the third semiconductor material layer 800 includes a plurality of third material layer sub-layers stacked in the first direction, the Si content of each third material layer sub-layer increases and the N content of each third material layer sub-layer decreases from layer to layer in the first direction, the Si content and the N content of each first material layer sub-layer are unchanged, each first material layer sub-layer is a layer close to the first diaphragm 210 in the first direction, each third material layer sub-layer is a layer close to the second diaphragm 220 in the second direction, the Si content and the N content of each third material layer sub-layer are unchanged, the first material layer sub-layers with the same serial numbers and the corresponding first material layers with the same serial numbers and the same thickness of the third material layer with the same serial numbers. The number of first material layer sub-layers in the first semiconductor material layer 300 is the same as the number of third material layer sub-layers in the third semiconductor material layer 800. Thereby, it is advantageous to achieve a symmetrical arrangement of the first support 510 and the third support 530.

In some embodiments, the process conditions of the first wet etch process are the same as the process conditions of the second wet etch process. Thereby, it is advantageous to achieve a symmetrical arrangement of the first support 510 and the third support 530.

The material of the second sacrificial layer 620 may include silicon oxide. Of course, the present application does not exclude the case that the material of the second sacrificial layer 620 is other materials, which is not limited in this embodiment.

Optionally, referring to fig. 1, the second diaphragm 220 includes a second movable region 221 and a second fixed region 222 located at an outer periphery of the second movable region 221, a second wet etching process is performed on the third semiconductor material layer 800, and a second bump structure 810 is further formed, where the second bump structure 810 is located on a side of the second diaphragm 220 facing the back plate 700 and is connected to the second movable region 221, and a cross-sectional area of the second bump structure 810 increases along a first direction, and a projection of the second bump structure 810 in the first direction falls within a projection range of the back plate 700.

The second protrusion structure 810 is formed on the second movable region 221 of the second diaphragm 220, so that the thickness of the second movable region 221 of the second diaphragm 220 is substantially increased, the strength of the second diaphragm 220 is increased, the risk of permanent deformation due to insufficient diaphragm strength is reduced, the projection of the second protrusion structure 810 falls into the projection range of the back plate 700, when the second diaphragm 220 moves towards the back plate 700, the second protrusion structure 810 replaces the second diaphragm 220 to contact with the back plate 700, the second protrusion structure 810 can serve as an anti-adhesion structure, adhesion to the back plate 700 during diaphragm vibration is avoided, the risk of device failure is reduced, the cross-sectional area of the second protrusion structure 810 is increased along the first direction, the contact area of the second protrusion structure 810 with the back plate 700 is reduced while the reinforcing effect of the strength of the second protrusion structure 810 on the second diaphragm 220 is guaranteed, the contact time of the second protrusion structure 810 with the back plate 700 is shortened, after the second protrusion structure 810 contacts with the back plate 700, the second protrusion structure 810 can be more rapidly separated from the back plate 700, the second diaphragm 220 can be kept in a permanent deformation state in the direction, and the risk of permanent deformation of the second diaphragm is reduced.

Optionally, referring to fig. 13, before forming the second diaphragm 220 on the third supporting portion 530, the method may further include forming a third sacrificial layer 630 covering a sidewall of the third supporting portion 530 and the second sacrificial layer 620, wherein a top surface of the third sacrificial layer 630 and a top end of the third supporting portion 530 form a flat plane, the top surface of the third sacrificial layer 630 is a surface of the third sacrificial layer 630 away from the second sacrificial layer 620, the top end of the third supporting portion 530 is an end of the third supporting portion 530 away from the second sacrificial layer 620, and the second diaphragm 220 covers the third sacrificial layer 630 and the third supporting 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 supporting portion 530 form a flat plane, so that the second diaphragm 220 can be prepared on the flat plane, the flatness of the second diaphragm 220 is ensured, and the reliability of the MEMS device is improved.

It will be appreciated that, in actual fabrication, a third sacrificial material layer covering the third supporting portion 530 and the second sacrificial layer 620 may be formed first, and then a planarization process is performed on the third sacrificial material layer so that a top surface of the third sacrificial layer 630 and a top end of the third supporting portion 530 form a flat plane.

The material of the third sacrificial layer 630 may include silicon oxide. Of course, the present application does not exclude the case where the material of the third sacrificial layer 630 is other materials, which is not limited in this embodiment.

In some embodiments, the second wet etching process is performed on the third semiconductor material layer 800, and a second reinforcing structure 910 is further formed on a side of the second diaphragm 220 facing the back plate 700, and a cross-sectional area of the second reinforcing structure 910 increases along the first direction, and in conjunction with fig. 1, after forming the back plate 700 on the first sacrificial layer 610 in a subsequent step, the method further includes removing a portion of the second sacrificial layer 620 and the third sacrificial layer 630, and forming the remaining second sacrificial layer 620 and the third sacrificial layer 630 as a second supporting structure 621 on the second fixing region 222, where a portion of the second reinforcing structure 910 is embedded in the second supporting structure 621. Thus, the second supporting structure 621 is arranged on the second diaphragm 220, so that the thickness of the second diaphragm 220 is further increased, the strength of the second diaphragm 220 is enhanced, the second reinforcing structure 910 and the third supporting portion 530 are formed on the basis of the same material layer in the same process, and the process and the cost are saved. It should be noted that, regarding the specific structure of the second reinforcing structure 910, reference may be made to the description of the third supporting portion 530 and fig. 3, and details thereof are not repeated herein.

In some embodiments, the surface layer of the first semiconductor material layer 300 on the side far from the first diaphragm 210 includes a first reserved area and a first etching area, the first reserved area is used for forming at least one of a top end of the first protruding structure 310, a top end of the first reinforcing structure 410 and a top end of the first supporting portion 510, the top end of the first protruding structure 310 is one end of the first protruding structure 310 far from the first diaphragm 210, the top end of the first reinforcing structure 410 is one end of the first reinforcing structure 410 far from the first diaphragm 210, the top end of the first supporting portion 510 is one end of the first supporting portion 510 far from the first diaphragm 210, and before the first wet etching process is performed 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 etching area, a projection of the first shielding portion covers a projection of the first reserved area in a first direction, and a projection area of the first shielding portion is larger than a projection area of the first reserved area. It will be appreciated that the wet etching is an isotropic etching, and the etchant will undercut the material layer, so that the size of the first shielding portion is larger than that of the first reserved area, and there is room for the process, so that the size of the finally prepared first bump structure 310, the first reinforcing structure 410 or the first supporting portion 510 is more accurate.

In some embodiments, the surface layer of the third semiconductor material layer 800 on the side far from the second sacrificial layer 620 includes a second reserved area and a second etching area, the second reserved area is used for forming at least one of a top end of the second protruding structure 810, a top end of the second reinforcing structure 910 and a top end of the third supporting portion 530, the top end of the second protruding structure 810 is one end of the second protruding structure 810 far from the second sacrificial layer 620, the top end of the second reinforcing structure 910 is one end of the third supporting portion 530 far from the second sacrificial layer 620, before the second wet etching process is performed 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 etching area, a projection of the second shielding portion covers a projection of the second reserved area in the first direction, and a projection area of the second shielding portion is larger than a projection area of the second reserved area. It will be appreciated that the wet etching is an isotropic etching, and the etchant will undercut the material layer, so that the second shielding portion is larger than the second retaining region, which allows room for the process, so that the size of the finally prepared second bump structure 810, second reinforcing structure 910 or third supporting portion 530 is more accurate.

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.

In some embodiments, the mask plate in the first photolithography process is the same shape as the mask plate in the second photolithography process. Further, the mask plate in the first photoetching process and the mask plate in the second photoetching process are the same mask plate. Specifically, when the first photoetching process is executed, a mask plate in the second photoetching process is adopted as the mask plate. Therefore, the preparation of the mask plate can be saved, and the working procedures and the cost are saved.

Next, referring to fig. 15, a back cavity 103 penetrating the substrate 100 is formed from the second surface 102 side.

Next, referring to fig. 1, a portion of the fourth sacrificial layer 640 is etched away to form a third cavity 603, a remaining fourth sacrificial layer 640 is formed as a third support structure 641 located on the first fixing region 212, a portion of the first sacrificial layer 610 is etched away to form a first cavity 601, a remaining first sacrificial layer 610 is formed as a first support structure 611 located on the first fixing region 212, a portion of the second sacrificial layer 620 and the third sacrificial layer 630 is etched away to form a second cavity 602, and a remaining second sacrificial layer 620 and third sacrificial layer 630 are formed as a second support structure 621 located on the second fixing region 222.

It should be noted that the embodiments of the MEMS device and the embodiments of the method for manufacturing the MEMS device provided by the present application belong to the same concept, and the technical features in the technical solutions described in the embodiments may be arbitrarily combined without any conflict. However, it should be further noted that the technical characteristics of the MEMS device provided by the embodiment of the present application may be combined to solve the technical problems to be solved by the present application, so that the MEMS device provided by the embodiment of the present application may not be limited by the method for manufacturing the MEMS device provided by the embodiment of the present application, and any MEMS device manufactured by the method for manufacturing the MEMS device structure provided by the embodiment of the present application is within the scope of protection of the present application.

It should be understood that the above examples are illustrative and are not intended to encompass all possible implementations. Various modifications and changes may be made in the above embodiments without departing from the scope of the disclosure. Likewise, the individual features of the above embodiments can also be combined arbitrarily to form further embodiments of the application which may not be explicitly described. Therefore, the above examples merely represent several embodiments of the present application and do not limit the scope of protection of the patent of the present application.

Claims

1. A MEMS device, comprising:

2. The MEMS device of claim 1, further comprising:

3. The MEMS device, as recited in claim 2,

4. The MEMS device of claim 1, further comprising:

a through opening penetrating the back plate along the first direction;

5. The MEMS device of claim 4, wherein the second diaphragm comprises a second movable region and a second fixed region located at an outer periphery of the second movable region;

6. A method of making a MEMS device, the method comprising:

Forming a first diaphragm on the first surface side, wherein the first diaphragm comprises a first movable area and a first fixed area positioned at the periphery of the first movable area;

7. The method of manufacturing a MEMS device of claim 6, wherein,

8. The method of manufacturing a MEMS device of claim 7, wherein,

9. The method of manufacturing a MEMS device of claim 6, wherein,

And forming a second vibrating diaphragm on the third supporting part.

10. The method of manufacturing a MEMS device according to claim 9, wherein the second diaphragm comprises a second movable region and a second fixed region located at an outer periphery of the second movable region;

11. The method of manufacturing a MEMS device according to claim 9, wherein before the second diaphragm is formed on the third supporting portion, the method further comprises forming a third sacrificial layer covering a sidewall of the third supporting portion and the second sacrificial layer, a top surface of the third sacrificial layer forming a flat plane with a top end of the third supporting portion, the top surface of the third sacrificial layer being a surface of the third sacrificial layer away from the second sacrificial layer, the top end of the third supporting portion being an end of the third supporting portion away from the second sacrificial layer;