WO2023087647A1

WO2023087647A1 - Mems microphone and manufacturing method therefor

Info

Publication number: WO2023087647A1
Application number: PCT/CN2022/094592
Authority: WO
Inventors: 冷华星
Original assignee: 无锡华润上华科技有限公司
Priority date: 2021-11-16
Filing date: 2022-05-24
Publication date: 2023-05-25
Also published as: CN116137694A

Abstract

An MEMS microphone and a manufacturing method therefor. The MEMS microphone comprises: a substrate (110); a backplate (130) arranged on the substrate (110); a plurality of support columns (144) arranged on the substrate (110); and a diaphragm (150) arranged on the support columns (144), wherein each of the support columns (144) is used for supporting the diaphragm (150); the diaphragm (150) is provided with an air hole (151), and penetrates the diaphragm (150); an airflow channel is formed in a space located between the diaphragm (150) and the backplate (130) and provided with no support column (144); the substrate (110) directly below the backplate (130) is not provided with a cavity; and the backplate (130) and the diaphragm (150) form a capacitor.

Description

MEMS microphone and manufacturing method thereof

Cross References to Related Applications

This application claims the priority of the Chinese patent application with the application number 2021113547454 and the title of the invention "MEMS microphone and its manufacturing method" filed with the China Patent Office on November 16, 2021, the entire contents of which are incorporated by reference in this application.

technical field

The invention relates to the technical field of semiconductor devices, in particular to a MEMS microphone and a method for manufacturing the MEMS microphone.

Background technique

The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

Micro-Electro-Mechanical System (MEMS) devices are usually produced using integrated circuit manufacturing techniques. Silicon-based microphones have broad application prospects in hearing aids and mobile communication equipment.

An exemplary MEMS microphone structure is shown in Figure 1, with a deep silicon etch cavity on the backside of the die (DIE). In operation, the gas passes through the acoustic hole of the microphone and finally exits the device through the deep silicon etch cavity.

However, the manufacturing cost of the MEMS microphone structure with deep silicon etching cavity structure is relatively high.

Contents of the invention

Based on this, it is necessary to provide a MEMS microphone with low manufacturing cost and a manufacturing method thereof.

A MEMS microphone, comprising: a substrate; a back plate, disposed on the substrate; a plurality of support columns, disposed on the substrate; a diaphragm, disposed on the support columns, each of the support columns For supporting the diaphragm, the diaphragm is provided with air holes, and the diaphragm is penetrated by the air holes; wherein, the space between the diaphragm and the back plate without each of the support columns forms an airflow channel, the substrate directly below the backplane does not have a cavity, and the backplane and diaphragm form a capacitor.

A method for manufacturing a MEMS microphone, comprising: forming a back plate on a substrate; forming a sacrificial layer on the back plate; patterning the sacrificial layer to form a plurality of support pillar filling holes; filling the holes in each support pillar forming support columns; forming a diaphragm directly in contact with each support column on the sacrificial layer, and air holes penetrating the diaphragm; removing the sacrificial layer outside the area surrounded by each support column; forming a The first welding pad on the upper surface of the backplane, and the second welding pad located on the upper surface of the diaphragm; removing the sacrificial layer inside the area surrounded by each of the supporting pillars.

The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects and advantages of the present application will be apparent from the description, drawings and claims.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the traditional technology. Obviously, the accompanying drawings in the following description are only the present invention For some embodiments of the application, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of an exemplary MEMS microphone structure;

Fig. 2 is a schematic cross-sectional view of a MEMS microphone structure in an embodiment;

Fig. 3 is a three-dimensional schematic diagram of a support column under the diaphragm in an embodiment;

Fig. 4 is the flowchart of the manufacturing method of MEMS microphone in an embodiment;

5a to 5g are schematic cross-sectional views of the device structure in the process of manufacturing the MEMS microphone by the manufacturing method shown in FIG. 4 in an embodiment;

6 is a schematic cross-sectional view of a MEMS microphone structure in another embodiment;

7a to 7e are schematic cross-sectional views of the device structure in the process of manufacturing the MEMS microphone by the manufacturing method shown in FIG. 4 in another embodiment.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the associated drawings. A preferred embodiment of the invention is shown in the drawings. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that 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 the other element or layer. A layer may be on, adjacent to, connected to, or coupled to other elements or layers, 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. layer. It will be understood that, although the terms first, second, third etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatial terms such as "below", "below", "below", "under", "on", "above", etc., in This may be used for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "below" or "beneath" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below" and "beneath" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial 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 invention. As used herein, the singular forms "a", "an" and "the/the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the terms "consists of" and/or "comprising", when used in this specification, identify the presence of stated features, integers, steps, operations, elements and/or parts, but do not exclude one or more other Presence or addition of features, integers, steps, operations, elements, parts and/or groups. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

Embodiments of the invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes shown are to be expected due to, for example, manufacturing techniques and/or tolerances. Thus, embodiments of the invention should not be limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation was performed. Thus, the regions shown in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the invention.

The semiconductor field vocabulary used in this article is a technical vocabulary commonly used by those skilled in the art. For example, for P-type and N-type impurities, in order to distinguish the doping concentration, P+ type simply represents P-type with heavy doping concentration, and P-type represents medium P-type with doping concentration, P-type represents P-type with light doping concentration, N+ type represents N-type with heavy doping concentration, N-type represents N-type with medium doping concentration, and N-type represents light-doped concentration Type N.

The MEMS microphone structure shown in Figure 1 requires the formation of deep silicon etch cavities. Exemplary deep silicon etching chamber preparation methods include KOH (potassium hydroxide) wet etching and ICP (Inductively Coupled Plasma, inductively coupled plasma) dry etching, both of which are very expensive in terms of individual processing costs. The depth of the deep silicon etch chamber depends on the thickness of the substrate, usually 400 microns. The preparation of the process is usually to thin the wafer from the conventional thickness of 725 microns to 400 microns, and then perform deep silicon etching on the back to form a deep silicon etching cavity. If it is thinner, the wafer will become softer, and the warpage of the wafer will become larger, making it difficult to carry out subsequent backside lithography and etching, including wafer transportation and adsorption, which are prone to problems. This thinned thickness restricts the height of the device after packaging (the thickness of the wafer is not less than 400 microns, resulting in a higher height of the device after packaging), and the cost of subsequent laser scribing cannot be reduced due to the thicker wafer. This application removes the deep silicon etching cavity from the design, avoiding this cost. At the same time, the process can also realize the thinning of the wafer with the maximum thickness, and realize the thinnest substrate as possible.

FIG. 2 is a schematic cross-sectional structure diagram of a MEMS microphone in an embodiment. It is a capacitive MEMS microphone, including a substrate 110 , a back plate 130 , a support column 144 and a diaphragm 150 . The backplane 130 is disposed on the substrate 110 . Each support column 144 is disposed on the substrate 110 to support the diaphragm 150 . In one embodiment of the present application, the support columns 144 are distributed around the edge of the diaphragm 150 , as shown in FIG. 3 . In FIG. 3, each support column 144 is transparently processed. The diaphragm 150 and the back plate 130 form a flat plate capacitor, and the diaphragm 150 and the back plate 130 serve as the upper and lower plates of the capacitor respectively. The air hole 151 is provided through the diaphragm 150 , and the airflow can pass through the diaphragm 150 through the air hole 151 and flow out from the side of the support post 144 (through the gap between the support post and other support posts). Since the sides are used as gas flow channels, no cavities (deep etch cavities) are provided on the substrate 110 directly below the back plate 130 .

In the above-mentioned MEMS microphone, the airflow with sound waves can enter from the air hole 151 and flow out from the airflow channel between the diaphragm 150 and the backplate 130, so the substrate 110 directly below the backplate 130 is not provided with a deep etching cavity, which can save etching. The cost of etching to form a deep etch cavity. And because the substrate 110 under the back plate 130 is a solid structure without a cavity, the substrate 110 will not be too soft and warped if it is thinned to a very thin thickness, thereby reducing the scribing cost.

In one embodiment of the present application, the material of the substrate 110 is Si. In other embodiments, the material of the substrate 110 may also be other semiconductors or semiconductor compounds, such as one of Ge, SiGe, SiC, SiO ₂ or Si ₃ N ₄ .

FIG. 6 is a schematic cross-sectional view of a MEMS microphone structure in another embodiment. The main difference between it and the embodiment shown in FIG. 2 is that, compared with the structure shown in FIG. 6, FIG. 2 adds a dielectric layer 142 disposed on the back plate 130 , one end of each supporting column 144 is in direct contact with the dielectric layer 142 , and the other end is in direct contact with the diaphragm 150 .

In the embodiment shown in FIG. 2 , an insulating layer 120 is further provided between the substrate 110 and the backplane 130 . The insulating layer 120 is used to insulate the substrate 110 and the backplane 130 from each other. In one embodiment of the present application, the material of the insulating layer 120 is silicon oxide, such as silicon dioxide.

In one embodiment of the present application, the diaphragm 150 is a flexible film, and the back plate 130 is a rigid film. Specifically, the vibrating membrane 150 is a layer of flexible film with tensile stress and conductivity, which can deform to a certain extent when the surrounding air vibrates, and forms a flat capacitor together with the back plate 130 as one pole of the flat capacitor. Since the substrate under the backplane 130 is not provided with a deep etching cavity, the backplane 130 is no longer separated from the substrate 110 (and the insulating layer 120 ), and the backplane 130 is fixed by the substrate 110 so that the diaphragm 150 is fixed when it vibrates. The substrate 110 forms a good support for the back plate 130 , so it is no longer necessary to place a large stress on the back plate 130 to ensure that the diaphragm 150 remains stationary when it vibrates. In one embodiment of the present application, the diaphragm 150 is softer than the back plate 130 .

In the embodiment shown in FIG. 2 , the air hole 151 is a circular air hole located in the middle of the diaphragm 150 . In other embodiments, a plurality of air holes 151 penetrating the vibrating membrane 150 can also be provided, and the air holes 151 can be in other shapes, such as oval, square or irregular patterns, and the specific shape and quantity of the air holes 151 can vary according to different devices. Depending on performance requirements. In an embodiment of the present application, each air hole 151 is located in the area surrounded by the orthographic projection of each supporting column 144 on the diaphragm 150 .

The diaphragm 150 and the back plate 130 are both conductive materials. In other embodiments, the diaphragm 150 and the back plate 130 may also be a composite layer structure including a conductive layer, such as one or more of the following materials: Si, Ge, SiGe, SiC, Al, W, Ti , or Al/W/Ti nitrides. In one embodiment of the present application, the material of the diaphragm 150 includes polysilicon. In one embodiment of the present application, the material of the backplane 130 includes polysilicon.

It can be understood that FIG. 2 is an example of some main structures of the MEMS microphone, and the MEMS microphone may have other structures besides the structures shown in the figure.

In the embodiment shown in FIG. 3 , the diaphragm 150 has a circular cross section.

In one embodiment of the present application, the cavity between the diaphragm 150 and the dielectric layer 142 is formed by releasing the sacrificial layer. During the release process, the sacrificial layer at the position of the cavity is corroded, thereby forming cavity. In one embodiment of the present application, the release of the sacrificial layer is accomplished by wet etching. The etching solution for wet etching is BOE (Buffered Oxide Etch, buffered oxide etching solution), and the dielectric layer 142 and each support pillar 144 are made of materials resistant to corrosion by the buffered oxide etching solution. In one embodiment of the present application, the material of the dielectric layer 142 and each support pillar 144 is silicon nitride.

In one embodiment of the present application, the MEMS microphone further includes a first solder pad 162 disposed on the upper surface of the back plate 130 , and a second solder pad 164 disposed on the upper surface of the diaphragm 150 . In one embodiment of the present application, both the first pad 162 and the second pad 164 are made of metal, the first pad 162 is electrically connected to the backplane 130, and the second pad 164 is electrically connected to the diaphragm 150 . The first pad 162 and the second pad 164 can lead out the back plate 130 /diaphragm 150 when the MEMS microphone package is bonded.

The present application also provides a method for manufacturing a MEMS microphone, which can be used to manufacture the MEMS microphone described in any of the above embodiments. Fig. 4 is the flowchart of the manufacturing method of MEMS microphone in an embodiment, comprises the following steps:

S410, forming a backplane on the substrate.

Referring to FIG. 5 a , in one embodiment of the present application, polysilicon (Poly) may be deposited as the backplane 130 .

In the embodiment shown in FIG. 5a, before depositing polysilicon, a step of forming an insulating layer 120 on the substrate 110 is also included. Polysilicon is deposited on the insulating layer 120 . In one embodiment of the present application, the insulating layer 120 is formed by depositing silicon dioxide. In other embodiments, the insulating layer 120 may also be formed by thermal growth.

S420, forming a sacrificial layer on the backplane.

Referring to FIG. 5 b , in one embodiment of the present application, before forming the sacrificial layer 141 , a step of forming a dielectric layer 142 on the backplane 130 is also included. The dielectric layer 142 is made of BOE corrosion resistant material. Specifically, silicon nitride can be deposited on the backplane 130, and then the silicon nitride layer can be patterned (specifically, a photoresist can be coated on the silicon nitride layer, and then a corresponding photoresist plate can be used to expose the photoresist. develop, and etch the silicon nitride layer, and then remove the photoresist), to obtain the dielectric layer 142 .

In other embodiments, the dielectric layer 142 may not be provided, and the structure obtained after step S420 is as shown in FIG. 7 a .

In one embodiment of the present application, silicon dioxide may be deposited on the backplane 130 and the dielectric layer 142 as the sacrificial layer 141 .

S430, patterning the sacrificial layer to form a plurality of supporting pillars filling the holes.

In one embodiment of the present application, a photoresist is coated on the sacrificial layer 141, and then a corresponding photoresist is used to expose the photoresist for development, and the sacrificial layer 141 is etched, and then the photoresist is removed. A support column filling hole 143 is formed at the position where the support column needs to be provided, as shown in FIG. 5c.

For the embodiment without the dielectric layer 142, the structure obtained after step S430 is as shown in FIG. 7b.

S440, forming a support column in each support column filling hole.

In one embodiment of the present application, a material resistant to BOE corrosion is deposited on the surface of the wafer, and the material is filled into each support column filling hole 143 to form a support column, as shown in FIG. 5d. Specifically, the material resistant to BOE corrosion may be silicon nitride. Excess (ie, on sacrificial layer 141 ) silicon nitride may be removed after deposition.

For the embodiment without the dielectric layer 142, the structure obtained after step S440 is as shown in FIG. 7c.

S450, forming a vibrating film in direct contact with each supporting column on the sacrificial layer, and air holes penetrating through the vibrating film.

In one embodiment of the present application, polysilicon is deposited on the sacrificial layer 141, and then the deposited polysilicon is patterned to obtain a diaphragm 150, as shown in FIG. 5e. Specifically, a photoresist may be coated on the polysilicon, and then a corresponding photoresist is used to expose the photoresist for development, and the polysilicon is etched to obtain the diaphragm 150, and then the photoresist is removed. An air hole 151 is formed at the center of the diaphragm 150 .

For the embodiment without the dielectric layer 142, the structure obtained after step S450 is as shown in FIG. 7d.

S460, removing the sacrificial layer outside the area surrounded by each support column.

Referring to FIG. 5 f , the sacrificial layer 141 outside each support pillar 144 is removed by an etching process, and the sacrificial layer 141 inside each support pillar 144 remains. The remaining sacrificial layer 141 can block the air hole 151 at the bottom of the air hole 151, so as to prevent the pad material deposited in the subsequent process from filling through the air hole 151 (accumulating on the dielectric layer 142).

For the embodiment without the dielectric layer 142, the structure obtained after step S460 is as shown in FIG. 7e.

S470, forming a first pad located on the upper surface of the backplane and a second pad located on the upper surface of the backplane.

In one embodiment of the present application, a metal layer is deposited, and then the first pad 162 on the upper surface of the backplane 130 and the first pad 162 on the upper surface of the diaphragm 164 are formed by pad (PAD) metal lithography and etching. The second pad 164, refer to FIG. 5g. The first pad 162 is electrically connected to the back plate 130 , and the second pad 164 is electrically connected to the diaphragm 150 . The first pad 162 and the second pad 164 can lead out the back plate 130 /diaphragm 150 when the MEMS microphone package is bonded.

S480, removing the sacrificial layer inside the area surrounded by each support column.

The sacrificial layer 141 inside the supporting pillars is removed by wet etching. In one embodiment of the present application, the remaining sacrificial layer 141 is released by BOE etching to obtain the structure shown in FIG. 2 .

For the embodiment in which the dielectric layer 142 is not provided, the structure obtained after step S480 is as shown in FIG. 6 .

In one embodiment of the present application, before releasing the sacrificial layer 141 , a step of thinning the backside of the substrate 110 is also included to reduce the thickness of the substrate 110 to a required thickness.

For the MEMS microphone produced by the above MEMS microphone manufacturing method, the airflow with sound waves can enter from the air hole 151 and flow out from the airflow channel between the diaphragm 150 and the back plate 130, so the above manufacturing method is not directly under the back plate 130 The substrate 110 is provided with a deep etch cavity, which can save the cost of etching to form the deep etch cavity. Moreover, since the substrate 110 under the back plate 130 is a solid structure without a cavity, the substrate 110 will not be too soft and warped if it is thinned to a very thin thickness, thereby reducing the scribing cost.

In one embodiment of the present application, the diaphragm 150 is a flexible film, and the back plate 130 is a rigid film. Specifically, the vibrating membrane 150 is a layer of flexible film with tensile stress and conductivity, which can deform to a certain extent when the surrounding air vibrates, and forms a flat capacitor together with the back plate 130 as one pole of the flat capacitor. Since the substrate under the backplane 130 is not provided with a deep etching cavity, the backplane 130 is no longer separated from the substrate 110 (and the insulating layer 120 ), and the backplane 130 is fixed by the substrate 110 so that it is fixed when the diaphragm 150 vibrates. The substrate 110 forms a good support for the back plate 130 , so it is no longer necessary to place a large stress on the back plate 130 to ensure that the diaphragm 150 remains stationary when it vibrates. In one embodiment of the present application, the diaphragm 150 is softer than the back plate 130 .

It should be understood that although the various steps in the flow chart of the present application are displayed in sequence according to the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in the flow chart of the present application may include multiple steps or stages, and these steps or stages are not necessarily executed at the same time, but may be executed at different times, and the steps or stages The execution sequence is not necessarily performed sequentially, but may be performed alternately or alternately with other steps or at least a part of steps or stages in other steps.

In the description of this specification, descriptions referring to the terms "some embodiments", "other embodiments", "ideal embodiments" and the like mean that specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in this specification. In at least one embodiment or example of the invention. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features of the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered to be within the range described in this specification.

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims

A MEMS microphone comprising:

Substrate;

a backplane disposed on the substrate;

a plurality of supporting pillars arranged on the substrate;

The diaphragm is arranged on the support columns, each of the support columns is used to support the diaphragm, the diaphragm is provided with air holes, and the diaphragm is penetrated by the air holes;

Wherein, the space between the diaphragm and the back plate is not provided with each of the support columns to form an air flow channel, the substrate directly below the back plate is not provided with a cavity, and the back plate and the diaphragm form a capacitor .
The MEMS microphone according to claim 1, further comprising a dielectric layer disposed on the back plate, one end of each of the supporting posts is in direct contact with the dielectric layer, and the other end is in direct contact with the vibration layer. membranes in direct contact.
The MEMS microphone according to claim 2, wherein the dielectric layer and each support column are made of materials resistant to corrosion by a buffer oxide etchant.
The MEMS microphone according to claim 1, wherein an insulating layer is further provided between the substrate and the back plate.
The MEMS microphone according to claim 1, wherein the diaphragm is a flexible film layer, and the back plate is a rigid film layer.
The MEMS microphone according to claim 1, wherein the material of the back plate comprises polysilicon, and/or the material of the diaphragm comprises polysilicon.
The MEMS microphone according to claim 1, wherein the diaphragm is provided with a plurality of air holes, and each of the air holes is located in an area surrounded by the orthographic projection of each of the support columns on the diaphragm.
MEMS microphone according to claim 1, is characterized in that, also comprises:

The first pad is arranged on the upper surface of the backplane;

The second welding pad is provided on the upper surface of the diaphragm.
The MEMS microphone according to claim 1, wherein the material of the first pad and the second pad is conductive metal or conductive alloy.
A method of manufacturing a MEMS microphone, comprising:

forming a backplane on the substrate;

forming a sacrificial layer on the backplane;

patterning the sacrificial layer to form a plurality of support post-filled holes;

forming a support post in each support post fill hole;

forming a diaphragm directly in contact with each support column on the sacrificial layer, and an air hole penetrating through the diaphragm;

removing the sacrificial layer outside the area surrounded by each of the support columns;

forming a first solder pad located on the upper surface of the backplane, and a second solder pad located on the upper surface of the diaphragm;

The sacrificial layer inside the area surrounded by each of the supporting pillars is removed.
The method according to claim 10, characterized in that, before the step of forming the backplane on the substrate, it also includes the step of forming an insulating layer on the substrate, and the step of forming the backplane on the substrate is A backplane is formed on the insulating layer.
The method according to claim 10, further comprising the step of forming a dielectric layer on the backplane before the step of forming a sacrificial layer on the backplane, and the step of forming a dielectric layer on the backplane The step of forming a sacrificial layer is to form a sacrificial layer on the dielectric layer.
The method according to claim 10, characterized in that, the dielectric layer and each support pillar are made of a material resistant to corrosion by a buffer oxide etchant, and the step of removing the sacrificial layer on the inner side of the support pillar The sacrificial layer is removed by etching with a buffered oxide etchant.
The method according to claim 10, wherein the step of forming a backplane on the substrate comprises depositing polysilicon as the backplane;

The step of forming a diaphragm in direct contact with each support column on the sacrificial layer and air holes penetrating through the diaphragm includes: depositing polysilicon on the sacrificial layer, and then patterning the deposited polysilicon to obtain the diaphragm.
The method according to claim 10, wherein the diaphragm is a flexible film layer, the diaphragm is a flexible film layer, and the back plate is a rigid film layer.