Method for manufacturing MEMS microphone and MEMS microphone

Abstract

Embodiments of the present application relate to a preparation method of a MEMS microphone and the MEMS microphone. The preparation method comprises the following steps: providing a substrate, the substrate comprising a conductive region; forming a groove extending from a surface of the substrate to an interior; depositing an insulating material on the substrate to form an insulating isolation structure filled in the groove; forming a diaphragm and a back plate on the substrate, the diaphragm and the back plate being used to constitute a variable capacitor; forming a first electrode in conductive connection with the conductive region, a second electrode in conductive connection with the diaphragm, and a third electrode in conductive connection with the back plate; wherein a vertical projection of the second electrode on the surface of the substrate at least partially coincides with a forming position of the groove; in this way, the insulating isolation structure is used to improve a parasitic capacitance problem between the first electrode and the second electrode, and the sensitivity of the MEMS microphone is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated circuits, and in particular to a preparation method of a MEMS microphone and a MEMS microphone. BACKGROUND

[0002] The MEMS microphone refers to a microphone device prepared by a micro-electro-mechanical system (MEMS) process. The MEMS microphone is widely applied to mobile phones, earphones, notebook computers, video cameras and other devices due to its characteristics of miniaturization and thinness.

[0003] The existing MEMS microphone vibrates under the action of air flow during work, causing the capacitance between the diaphragm and the back plate to change, thereby converting the sound signal into an electrical signal. However, a parasitic capacitance may be formed inside the MEMS microphone during work, which seriously affects the sensitivity of the device. SUMMARY

[0004] Therefore, the embodiments of the present application provide a preparation method of a MEMS microphone and a MEMS microphone to solve at least one problem in the background art.

[0005] In a first aspect, the embodiments of the present application provide a preparation method of a MEMS microphone, and the method comprises:

[0006] providing a substrate, the substrate comprising a conductive region;

[0007] forming a groove extending from a surface of the substrate to an interior of the substrate;

[0008] depositing an insulating material on the substrate to form an insulating isolation structure filled in the groove;

[0009] forming a diaphragm and a back plate on the substrate, the diaphragm and the back plate being used to constitute a variable capacitor;

[0010] forming a first electrode in conductive connection with the conductive region, a second electrode in conductive connection with the diaphragm, and a third electrode in conductive connection with the back plate;

[0011] wherein a vertical projection of the second electrode on the surface of the substrate at least partially overlaps with a formation position of the groove.

[0012] In combination with the first aspect of the present application, in an optional implementation, the conductive region is formed by ion implantation on the substrate from the surface of the substrate, and the depth of ion implantation is a first depth.

[0013] The forming the recess extending from the surface of the substrate to the interior of the substrate comprises: forming a recess extending from the surface of the substrate to the interior of the substrate by a second depth;

[0014] The second depth is greater than or equal to the first depth.

[0015] With reference to the first aspect of the present application, in an optional implementation, the depositing the insulating material on the substrate comprises:

[0016] depositing the insulating material on the surface of the substrate and in the recess to form an insulating isolation structure filling the recess and a first sacrificial layer covering the surface of the substrate and the insulating isolation structure;

[0017] The first sacrificial layer is configured to be removed at least partially to form a cavity under the diaphragm.

[0018] With reference to the first aspect of the present application, in an optional implementation, after the depositing the insulating material on the substrate, the method further comprises:

[0019] performing a first planarization treatment on the upper surface of the first sacrificial layer by using a chemical mechanical polishing process;

[0020] performing a second planarization treatment on the upper surface of the first sacrificial layer by using a trimming process.

[0021] With reference to the first aspect of the present application, in an optional implementation, the insulating material comprises silicon dioxide.

[0022] With reference to the first aspect of the present application, in an optional implementation, a vertical projection of the second electrode on the surface of the substrate falls within the range of the insulating isolation structure.

[0023] In a second aspect, the embodiments of the present application provide a MEMS microphone, comprising:

[0024] a substrate comprising a conductive region;

[0025] a diaphragm and a back plate on the substrate, the diaphragm and the back plate forming a variable capacitance;

[0026] a first electrode, a second electrode and a third electrode, which are respectively in conductive connection with the conductive region, the diaphragm and the back plate;

[0027] an insulating isolation structure extending from a surface of the substrate facing the diaphragm to the interior of the substrate, and a vertical projection of the second electrode on the surface of the substrate at least partially overlaps with the insulating isolation structure.

[0028] In an optional implementation of the second aspect of the present application, the insulating isolation structure extends through the conductive region.

[0029] In an optional implementation of the second aspect of the present application, a vertical projection of the second electrode on the surface of the substrate falls within the range of the insulating isolation structure.

[0030] In an optional implementation of the second aspect of the present application, a material of the insulating isolation structure comprises silicon dioxide.

[0031] The preparation method and the MEMS microphone provided by the embodiments of the present application comprise the following steps: providing a substrate, the substrate comprising a conductive region; forming a groove extending from a surface of the substrate to an interior; depositing an insulating material on the substrate to form an insulating isolation structure filled in the groove; forming a diaphragm and a back plate on the substrate, the diaphragm and the back plate being used to constitute a variable capacitor; forming a first electrode in conductive connection with the conductive region, a second electrode in conductive connection with the diaphragm, and a third electrode in conductive connection with the back plate; wherein a vertical projection of the second electrode on the surface of the substrate at least partially coincides with a forming position of the groove; in this way, the insulating isolation structure is used to improve a parasitic capacitance problem between the first electrode and the second electrode, and the sensitivity of the MEMS microphone is improved.

[0032] Additional aspects and advantages of the present application will be made apparent by the following description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are included to provide a further understanding of the present application, constitute a part of the present application, illustrate the illustrative embodiments of the present application and the description thereof, and serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0034] Figure 1 It is a cross-sectional structure schematic diagram of a MEMS microphone in a related art of the present application;

[0035] Figure 2 It is a flowchart schematic diagram of a preparation method of a MEMS microphone provided by the embodiments of the present application;

[0036] Figures 3 to 16 It is a cross-sectional structure schematic diagram of a MEMS microphone in a preparation process provided by the embodiments of the present application;

[0037] Figure 17 It is a cross-sectional structure schematic diagram of a MEMS microphone provided by a specific example of the present application. DETAILED DESCRIPTION

[0038] Exemplary embodiments of the present application will be described herein below with reference to the accompanying drawings. While exemplary embodiments of the present application are illustrated, it will be understood that the present application can be carried out in various ways without being limited to the particular embodiments set forth herein. Conversely, additional embodiments of the present application can from time to time be set forth, of which the person of ordinary skill in the art will avail himself / herself by virtue of the conceptual description of the application as set forth herein.

[0039] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one of ordinary skill in the art that the present application can be practiced without one or more of these specific details. In other instances, well-known features have not been described in detail so as not to unnecessarily obscure the present application.

[0040] In the drawings, the size of layers, regions, elements, and the like can be exaggerated for clarity. Like reference numerals can represent like elements throughout the several figures.

[0041] It will be understood that when an element or layer is referred to as being "on" or "adjacent" another element or layer, it can be directly on or adjacent the other element or layer or intervening elements or layers can also be present. In contrast, when an element is referred to as being "directly on" or "directly adjacent" another element or layer, there are no intervening elements or layers present. It will also be understood that, when an element is referred to as being "connected" or "coupled" to another element or layer, it can be directly connected or coupled to the other element or layer or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can 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. Similarly, a second element, component, region, layer or section discussed below could be termed a first element, component, region, layer or section without departing from the teachings of the present application.

[0042] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptions used herein interpreted accordingly.

[0043] 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 one or more of the associated listed items.

[0044] For a thorough understanding of the application, detailed descriptions will be made in the following description of specific embodiments and specific structures, in order to explain the technical solutions of the application. The preferred embodiments of the application are described in detail as follows, however, in addition to these detailed descriptions, the application can also have other implementation manners.

[0045] Figure 1 A cross-sectional structure of a MEMS microphone in the related art of the application is shown. As shown in the figure, the MEMS microphone comprises a substrate 110, a diaphragm 140 and a back plate 170 formed on the substrate 110; wherein the diaphragm 140 and the back plate 170 constitute a variable capacitor, the diaphragm 140 vibrates under the action of air flow, causing the change of the capacitance between the diaphragm 140 and the back plate 170, thereby converting the sound signal into an electric signal. The second electrode 182 and the third electrode 183 are respectively in conductive connection with the diaphragm 140 and the back plate 170, for extracting the electric signal. In addition, the first electrode 181 is in conductive connection with the substrate 110, for leading away the charge on the surface of the substrate 110, avoiding interference to the above-mentioned electric signal.

[0046] However, during the operation of the MEMS microphone, a parasitic capacitance can be formed between the first electrode 181 and the second electrode 182, seriously affecting the sensitivity of the MEMS microphone.

[0047] To solve the above problems, the application provides a preparation method of a MEMS microphone and the MEMS microphone.

[0048] First, refer to Figure 2 . As shown in the figure, the preparation method of the MEMS microphone provided by the application comprises:

[0049] Step S01, providing a substrate, the substrate comprising a conductive region;

[0050] Step S02, forming a groove extending from the surface of the substrate to the interior;

[0051] Step S03, depositing an insulating material on the substrate to form an insulating isolation structure filled in the groove;

[0052] Step S04, forming a diaphragm and a back plate on the substrate, the diaphragm and the back plate being used to constitute a variable capacitor;

[0053] Step S05, forming a first electrode in conductive connection with the conductive region, a second electrode in conductive connection with the diaphragm, and a third electrode in conductive connection with the back plate;

[0054] The vertical projection of the second electrode on the surface of the substrate at least partially coincides with the forming position of the groove.

[0055] It can be understood that the application utilizes the insulating isolation structure to improve the parasitic capacitance problem between the first electrode and the second electrode, and improves the sensitivity of the MEMS microphone.

[0056] Next, in combination with the cross-sectional structure schematic diagram of the MEMS microphone in the preparation process shown in Figures 3 to 16 , the preparation method of the MEMS microphone shown in Figure 2 is further described in detail.

[0057] First, refer to Figure 3 . Step S01 is performed to provide a substrate 110, the substrate 110 comprising a conductive region (not shown in the figure).

[0058] The material of the substrate 110 can be any suitable base material known to those skilled in the art, for example, can be at least one of the following materials: silicon, germanium, silicon-on-insulator (SOI), germanium-on-insulator (GeOI), etc. The application takes the silicon substrate as an example for illustration.

[0059] The substrate 110 can comprise an upper surface 111 and a lower surface 112 opposite to each other. Among them, the upper surface 111 is usually the side forming the MEMS microphone, which can be referred to as "the surface 111 of the substrate facing the diaphragm" or "the surface 111 of the substrate" hereinafter.

[0060] The substrate 110 includes a conductive region, which can be a partial region of the substrate 110 or a whole conductive substrate.

[0061] Referring to Figure 17 In an example, the substrate 110 includes a conductive region 114. The conductive region 114 extends from the upper surface 111 to the interior of the substrate 110. In actual production, the conductive region 114 is formed by, for example, ion implantation on the surface 111 of the substrate 110, and the depth of ion implantation is a first depth.

[0062] The conductive region 114 can be formed in the entire surface layer region of the substrate 110 or in a partial surface layer region.

[0063] The conductive region 114 can be N-type. For example, when the substrate 110 is a silicon substrate, the conductive region 114 can be formed by phosphorus doping on the silicon substrate.

[0064] In addition, the substrate 110 can be an N-type substrate as a whole.

[0065] Next, referring to Figure 4 Step S02 is performed to form a groove 113 extending from the surface 111 to the interior of the substrate 110.

[0066] In actual production, a photoresist can be coated on the substrate 110 first, and then a patterned photoresist layer (not shown in the figure) is formed by exposure, development and other steps. The substrate 110 is etched using the patterned photoresist layer as a mask to form the groove 113.

[0067] The groove 113 is formed below the preset formation position of the second electrode. The formation position of the groove 113 at least partially overlaps with the preset formation position of the second electrode, so that the subsequent insulating isolation structure filled in the groove 113 can be located below the second electrode, thereby improving the parasitic capacitance problem between the second electrode and the first electrode.

[0068] Further, the formation position of the groove 113 can cover the preset formation position of the second electrode. In this way, after the insulating isolation structure and the second electrode are formed, the vertical projection of the second electrode on the surface 111 of the substrate 110 can fall within the range of the insulating isolation structure, so that the insulating isolation structure can better play an isolation role between the first electrode and the second electrode.

[0069] Optionally, the recess 113 can be formed in the range of the conductive region 114, and the subsequently formed insulating isolation structure can be surrounded by the conductive region 114. In this way, the insulating isolation structure is only formed at the position where it is necessary to avoid the generation of parasitic capacitance, and other positions are still used to guide the charges on the surface of the substrate 110 away.

[0070] In a specific example, the substrate 110 includes the conductive region 114, and the conductive region 114 has a first depth; and the recess 113 has a second depth; the second depth is greater than or equal to the first depth (for reference Figure 17 ). In this way, the part of the conductive region 114 at the position of the recess 113 is completely removed, and the subsequently formed insulating isolation structure can penetrate the conductive region 114, and better form the insulating isolation effect.

[0071] Next, please refer to Figure 5 Step S03 is performed, and the insulating material is deposited on the substrate 110 to form the insulating isolation structure 121 filled in the recess 113.

[0072] The insulating material can include silicon dioxide.

[0073] The insulating material can fill the recess 113. The shape, size and position of the insulating isolation structure 121 are consistent with those of the recess 113, and therefore, the shape, size and position of the insulating isolation structure 121 can be referred to the shape, size and position of the recess 113 described above.

[0074] As an optional embodiment, the deposition of the insulating material on the substrate 110 includes: depositing the insulating material on the surface 111 of the substrate 110 and in the recess 113 to form the insulating isolation structure 121 filled in the recess 113, and depositing a first sacrificial layer 122 on the surface 111 of the substrate 110 and on the insulating isolation structure 121. At least part of the first sacrificial layer 122 is used to be removed to form the cavity under the diaphragm. In this optional embodiment, the insulating isolation structure 121 can be formed by using the preparation process of the first sacrificial layer 122, without additional preparation process.

[0075] The deposition of the insulating material on the substrate 110 can be performed in multiple deposition modes.

[0076] Please continue to refer to Figure 5 Due to the presence of the recess 113, the upper surface of the first sacrificial layer 122 formed after the deposition of the insulating material has a pit 123, and the position of the pit 123 corresponds to the position of the recess 113.

[0077] Next, please refer to Figure 6 and Figure 7In order to make the subsequent process have a flat executable surface, the upper surface of the first sacrificial layer 122 can be subjected to a planarization treatment. Specifically, after the deposition of the insulating material on the substrate 110, the method further comprises: adopting a chemical mechanical polishing (CMP) process to perform a first planarization treatment on the upper surface of the first sacrificial layer 122 (as shown in FIG. 2B); and adopting a trimming process to perform a second planarization treatment on the upper surface of the first sacrificial layer 122 (as shown in FIG. 2C). Figure 6 Figure 7

[0078] After the first planarization treatment by the CMP process, the upper surface of the first sacrificial layer 122 can be relatively flat. Since in actual preparation, the depth of the groove 113 is often deep (such as greater than the depth of the conductive area 114), the upper surface cannot be formed flat enough by the CMP process alone. Therefore, the second planarization treatment is further performed by the trimming process to obtain the first sacrificial layer 122 with a more flat upper surface. The trimming process is specifically a dry trimming process, for example, a plasma trimming process.

[0079] Next, please refer to Figure 8 Part of the first sacrificial layer 122 is removed to facilitate the subsequent formation of the first electrode at this position.

[0080] In specific preparation, this step can be realized by a photolithography process, specifically for example: first, a photoresist is coated on the first sacrificial layer 122, and then a patterned photoresist layer (not shown in the figure) is formed through exposure, development and other steps. The first sacrificial layer 122 is etched using the patterned photoresist layer as a mask to expose the substrate 110.

[0081] Next, step S04 is performed to form a diaphragm and a back plate on the substrate 110, which are used to constitute a variable capacitor.

[0082] In actual preparation, forming the diaphragm and the back plate can include the following steps:

[0083] First, please refer to Figure 9 The first dielectric layer 130 is formed.

[0084] The first dielectric layer 130 covers the upper surface of the first sacrificial layer 122 and the upper surface of the exposed substrate 110. In specific preparation, a step of planarizing the upper surface of the first dielectric layer 130 can also be included.

[0085] The material of the first dielectric layer 130 includes, for example, silicon nitride.

[0086] Next, please refer to​​Figure 10 and Figure 11 The vibrating diaphragm 140 is formed.

[0087] The vibrating diaphragm 140 is specifically formed on the first dielectric layer 130.

[0088] The material of the vibrating diaphragm 140 can be a conductive material, thereby serving as a lower electrode (or lower plate) of the variable capacitor; and the material specifically includes, for example, polysilicon, SiGe, or metal, etc.

[0089] In actual production, the forming process of the vibrating diaphragm 140 can include: first depositing a layer of conductive material on the first dielectric layer 130, and then removing the unnecessary part through a photolithography process, thereby forming the vibrating diaphragm 140 meeting the design requirements.

[0090] Please continue to refer to Figure 11 A through hole 141 can be formed on the vibrating diaphragm 140, which penetrates the vibrating diaphragm 140. In the subsequent process, a gas leakage structure can be formed at the position of the through hole 141.

[0091] Next, please refer to Figure 12 and Figure 13 The second dielectric layer 150 is formed.

[0092] The material of the second dielectric layer 150 can be the same as that of the first dielectric layer 130, for example, both including silicon nitride.

[0093] When the silicon nitride is deposited to form the second dielectric layer 150, the silicon nitride not only covers the upper surface of the vibrating diaphragm 140, but also can be filled in the through hole 141. Further, the unnecessary part can be removed through a photolithography process; and in this process, the second dielectric layer 150 covering the sidewall of the through hole 141 can be reserved.

[0094] Next, please refer to Figure 14 The second sacrificial layer 160 is formed.

[0095] The second sacrificial layer 160 is specifically formed on the second dielectric layer 150 and fills the through hole 141. At least part of the second sacrificial layer 160 is used to be removed to form a cavity above the vibrating diaphragm 140.

[0096] The material of the second sacrificial layer 160 can be the same as that of the first sacrificial layer 122, for example, both including silicon dioxide.

[0097] Next, please refer to Figure 15 The back plate 170 is formed.

[0098] The material of the back plate 170 can also be a conductive material, thereby serving as an upper electrode (or upper plate) of the variable capacitor; and the material specifically includes, for example, metal, etc.

[0099] As shown in Figure 15 , the back plate 170 not only includes the portion formed on the second sacrificial layer 160, but also includes the portion in contact with the outer side surface of the second sacrificial layer 160. The portion in contact with the outer side surface of the second sacrificial layer 160 can be used as a support structure. Of course, the present application is not limited thereto, and those skilled in the art can also use other steps to form a support structure to ensure that a cavity can be formed between the back plate 170 and the diaphragm 140 after at least part of the second sacrificial layer 160 is removed, without collapsing.

[0100] Next, please refer to Figure 16 . Step S05 is performed to form the first electrode 181 in conductive connection with the conductive region, the second electrode 182 in conductive connection with the diaphragm 140, and the third electrode 183 in conductive connection with the back plate 170.

[0101] The vertical projection of the second electrode 182 on the surface 111 of the substrate 110 at least partially overlaps the formation position of the groove (see the insulating isolation structure 121 in the figure). Further, the vertical projection of the second electrode 182 on the surface 111 of the substrate 110 falls within the range of the insulating isolation structure 121.

[0102] The first electrode 181, the second electrode 182, and the third electrode 183 can be formed using common electrode materials, which are not specifically limited by the present application.

[0103] Please refer to Figure 17 , in a specific example, the first electrode 181 is in conductive connection with the conductive region 114.

[0104] In addition, for the case where the substrate 110 is a conductive substrate as a whole, the conductive connection between the first electrode 181 and the conductive region can be the conductive connection between the first electrode 181 and any part of the substrate 110; of course, in actual preparation, the conductive connection with the upper surface 111 of the substrate 110 is usually selected.

[0105] In order to form the first electrode 181 in conductive connection with the conductive region, the conductive region can be first exposed by etching process. Specifically, as shown in Figure 8 , the second dielectric layer 150 and the first dielectric layer 130 can be etched at the position where the first sacrificial layer 122 is removed, to form an opening (hereinafter referred to as "first opening") exposing the upper surface 111 of the substrate 110, and then the first electrode 181 is formed in the first opening.

[0106] Forming the second electrode 182 can include etching the back plate 170, the second sacrificial layer 160, and the second dielectric layer 150 to form an opening (hereinafter referred to as "second opening") exposing the diaphragm 140, and then forming the second electrode 182 in the second opening.

[0107] The forming of the third electrode 183 can include forming the third electrode 183 in contact with the back plate 170 on the upper surface of the back plate 170.

[0108] In addition, the method can further include a step of forming the acoustic hole 171 penetrating the back plate 170. When the MEMS microphone is working, air flow can enter the cavity through the acoustic hole 171 to cause the diaphragm 140 to vibrate, or air in the cavity is discharged through the acoustic hole 171.

[0109] In addition, the method can further include: removing at least part of the first sacrificial layer 122 to form a cavity (hereinafter referred to as "lower cavity 125") located below the diaphragm 140; and removing at least part of the second sacrificial layer 160 to form a cavity (hereinafter referred to as "upper cavity 162") located above the diaphragm 140. In this way, at least part of the diaphragm 140 is suspended between the upper cavity 162 and the lower cavity 125, and the upper cavity 162 and the lower cavity 125 provide a movable space for the diaphragm 140.

[0110] Please refer to Figure 16 Or Figure 17 Only part of the first sacrificial layer 122 can be removed, and the remaining first sacrificial layer 122 can be referred to as a lower support structure 124; in addition, only part of the second sacrificial layer 160 can be removed, and the remaining second sacrificial layer 160 can be referred to as an upper support structure 161. Thus, in the structure of the prepared MEMS microphone, the insulating isolation structure 121 is connected with the lower support structure 124, and both are formed in the same deposition process; the second electrode 182 is formed in the second opening penetrating the back plate 170, the upper support structure 161 and the second dielectric layer 150.

[0111] In addition, the method can further include removing part of the substrate 110 to form a back cavity 115 penetrating the substrate 110. The back cavity 115 is in communication with the lower cavity 125. In actual preparation, the back cavity 115 can be formed first, and then at least part of the first sacrificial layer 122 is removed through the back cavity 115 to form the lower cavity 125.

[0112] The second electrode 182 can be located between the first electrode 181 and the third electrode 183. Further, the second electrode 182 and the first electrode 181 can be located on the same side of the back cavity 115, and the third electrode 183 can be located on the other side of the back cavity 115. Of course, the present application is not limited thereto.

[0113] On this basis, the present application further provides a MEMS microphone, please refer to Figure 16 Or Figure 17The MEMS microphone comprises: a substrate 110 comprising a conductive region; a diaphragm 140 and a back plate 170 located on the substrate 110, the diaphragm 140 and the back plate 170 constituting a variable capacitor; a first electrode 181, a second electrode 182 and a third electrode 183, which are conductively connected with the conductive region, the diaphragm 140 and the back plate 170 respectively; and an insulating isolation structure 121 extending from a surface 111 of the substrate 110 facing the diaphragm 140 to the inside of the substrate 110, wherein a vertical projection of the second electrode 182 on the surface 111 of the substrate 110 at least partially overlaps the insulating isolation structure 121.

[0114] As an optional implementation, the insulating isolation structure 121 penetrates the conductive region 114.

[0115] As an optional implementation, a vertical projection of the second electrode 182 on the surface 111 of the substrate 110 falls within the range of the insulating isolation structure 121.

[0116] As an optional implementation, the material of the insulating isolation structure 121 comprises silicon dioxide.

[0117] It should be noted that the MEMS microphone embodiments provided in the present application and the preparation method embodiments of the MEMS microphone belong to the same concept; the technical features in the technical solutions recorded in each embodiment can be combined arbitrarily without conflict.

[0118] It should be understood that the above embodiments are exemplary and are not intended to include all possible embodiments of the claims. Various modifications and changes can also be made to the above embodiments without departing from the scope of the present disclosure. Similarly, any combination of the technical features of the above embodiments can be made to form additional embodiments of the present application that may not have been explicitly described. Therefore, the above embodiments only express several embodiments of the present application, and do not limit the protection scope of the patent of the present application.

Claims

1. A method of manufacturing a MEMS microphone, characterized by, The method comprises: providing a substrate comprising a conductive region; forming a recess extending from a surface of the substrate to an interior of the substrate, the recess having a depth greater than or equal to a depth of the conductive region, the recess being formed at a location within a range of the conductive region; depositing an insulating material on the substrate to form an insulating isolation structure filling the recess; forming a diaphragm and a back plate on the substrate, the diaphragm and the back plate being configured to constitute a variable capacitor; forming a first electrode in conductive connection with the conductive region, a second electrode in conductive connection with the diaphragm, and a third electrode in conductive connection with the back plate; wherein a vertical projection of the second electrode on the surface of the substrate at least partially overlaps with the location of the recess.

2. The method of claim 1, wherein the MEMS microphone is prepared by a method comprising: The conductive region is formed by ion implantation on the substrate from the surface of the substrate, the ion implantation having a first depth; The forming of the recess extending from the surface of the substrate to the interior of the substrate comprises forming a recess extending from the surface of the substrate to the interior of the substrate by a second depth; wherein the second depth is greater than or equal to the first depth.

3. The method of claim 1, wherein the MEMS microphone is prepared by: The depositing of the insulating material on the substrate comprises: depositing the insulating material on the surface of the substrate and in the recess to form an insulating isolation structure filling the recess, and a first sacrificial layer covering the surface of the substrate and the insulating isolation structure; wherein at least a portion of the first sacrificial layer is configured to be removed to form a cavity below the diaphragm.

4. The method of claim 3, wherein the MEMS microphone is prepared by: After the depositing of the insulating material on the substrate, the method further comprises: performing a first planarization process on an upper surface of the first sacrificial layer using a chemical mechanical polishing process; performing a second planarization process on the upper surface of the first sacrificial layer using a trimming process.

5. The method of claim 3, wherein the MEMS microphone is prepared by: The insulating material comprises silicon dioxide.

6. The method of claim 1, wherein the MEMS microphone is prepared by: The vertical projection of the second electrode on the surface of the substrate falls within a range of the insulating isolation structure.

7. A MEMS microphone, characterized by Comprises: a substrate comprising a conductive region; a diaphragm and a back plate on the substrate, the diaphragm and the back plate being configured to constitute a variable capacitor; a first electrode, a second electrode, and a third electrode in conductive connection with the conductive region, the diaphragm, and the back plate, respectively; an insulating isolation structure extending from a surface of the substrate facing the diaphragm to an interior of the substrate, a vertical projection of the second electrode on the surface of the substrate at least partially overlapping with the insulating isolation structure; the insulating isolation structure penetrating the conductive region; in a plane parallel to the surface of the substrate, the insulating isolation structure is surrounded by the conductive region.

8. The MEMS microphone according to claim 7, characterized in that, The vertical projection of the second electrode on the surface of the substrate falls within a range of the insulating isolation structure.

9. The MEMS microphone of claim 7, wherein, The material of the insulating isolation structure comprises silicon dioxide. The material of the insulating isolation structure comprises silicon dioxide.

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