CN114513731B

CN114513731B - Microphone assembly and electronic equipment

Info

Publication number: CN114513731B
Application number: CN202210414860.4A
Authority: CN
Inventors: 荣根兰; 刘青
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2022-04-20
Filing date: 2022-04-20
Publication date: 2022-06-21
Anticipated expiration: 2042-04-20
Also published as: CN114513731A; WO2023202417A1

Abstract

The invention provides a microphone assembly and electronic equipment, wherein the microphone assembly comprises a substrate, a vibrating diaphragm and a back plate, and the vibrating diaphragm is positioned between the substrate and the back plate in a direction perpendicular to the plane of the substrate; at least one sound hole penetrating through the diaphragm in the thickness direction is formed in the sound wave conduction area of the diaphragm, a partial area of the substrate forms a first electrode, and the first electrode is provided with at least one first hollow-out area; a partial area of the back plate forms a second electrode, and the second electrode is provided with at least one second hollow area; the sound wave conduction area of the diaphragm forms a third electrode; in a direction perpendicular to the plane of the substrate, projections of the first electrode, the third electrode and the second electrode overlap. The technical scheme provided by the invention realizes the differential capacitance scheme of the single diaphragm and improves the performance of the microphone assembly.

Description

Microphone assembly and electronic equipment

Technical Field

The invention relates to the technical field of microphones, in particular to a microphone assembly and electronic equipment.

Background

A microphone is a pressure sensor that finally converts a sound pressure signal into an electrical signal, and a small microphone manufactured by using a Micro Electro Mechanical System (MEMS) technology is called a Micro-Electro-Mechanical System (MEMS) microphone or a Micro microphone. MEMS microphone chips generally include a substrate, a diaphragm, and a backplate. The vibrating diaphragm and the back plate are important parts in an MEMS microphone chip, the vibrating diaphragm and the back plate are arranged in parallel and at intervals, the vibrating diaphragm and the back plate form two electrode plates of the flat capacitor, the vibrating diaphragm is used for vibrating under the action of sound waves, and the relative distance between the back plate and the vibrating diaphragm is changed, so that the capacitance value of the flat capacitor is changed, the change of the capacitance value is converted into an electric signal through a peripheral circuit, and the conversion of sound and electricity is realized.

Most of the existing MEMS microphones are composed of an induction diaphragm and a rigid back plate, and the microphones have low linearity and large harmonic distortion. With the expansion of the application scenarios of the MEMS microphone (for example, the application scenario of singing with a mobile phone, etc.), the requirement of the user on the voice quality of the MEMS microphone is higher and higher. In order to improve the signal-to-noise ratio of the electrical signal sensed by the MEMS microphone, in the prior art, the MEMS microphone generally adopts a multi-diaphragm mode or a multi-back-plate mode to obtain a differential electrical signal, but this increases the size of the MEMS microphone, and cannot meet the requirement of electronic products for being light and thin. Accordingly, there is a need for improvements in the art.

Disclosure of Invention

The present invention is directed to at least one of the technical problems of the prior art, and provides a microphone assembly and an electronic device.

The purpose of the invention is realized by adopting the following technical scheme:

according to an aspect of the present invention, there is provided a microphone assembly comprising: the vibrating diaphragm is positioned between the substrate and the back plate in a direction perpendicular to the plane of the substrate; the diaphragm is provided with a sound wave conduction region, and at least one sound hole penetrating through the diaphragm in the thickness direction is formed in the sound wave conduction region so as to transmit sound waves from an external space; a partial area of the substrate forms a first electrode, and the first electrode is provided with at least one first hollow area; a partial area of the back plate forms a second electrode, and the second electrode is provided with at least one second hollow-out area; the sound wave conduction area of the diaphragm forms a third electrode; in a direction perpendicular to a plane of the substrate, projections of the first electrode, the third electrode and the second electrode are overlapped, and the substrate further has at least one fourth hollowed-out area surrounding the first electrode to form a back cavity.

Optionally, the first electrode has only one first hollow-out region, the second electrode has only one second hollow-out region, and in a direction perpendicular to the plane of the substrate, projections of the first hollow-out region and the second hollow-out region overlap.

Optionally, the first hollowed-out area of the first electrode is located in the center of the first electrode, and the second hollowed-out area of the second electrode is located in the center of the second electrode.

Optionally, the first electrode has at least two first hollow-out areas and/or the second electrode has at least two second hollow-out areas, and in a direction perpendicular to the plane where the substrate is located, projections of areas formed by all the first hollow-out areas and areas formed by all the second hollow-out areas at least partially overlap.

Optionally, the back plate further has at least one third hollow area surrounding the second electrode to reduce squeeze film damping between the back plate and the diaphragm.

Optionally, a first supporting body for supporting the diaphragm is disposed on one side of the substrate close to the diaphragm, and a second supporting body for supporting the back plate is disposed on one side of the diaphragm away from the substrate; the first support body is positioned at the edge of the substrate, so that the vibrating diaphragm is suspended above the first electrode, and the first electrode and the vibrating diaphragm form a first variable capacitor; the second support body is located at the edge of the vibrating diaphragm, so that the back plate is suspended above the vibrating diaphragm, and the second electrode and the vibrating diaphragm form a second variable capacitor.

Optionally, the substrate further comprises: at least one first beam fixedly connecting the first electrode with the first support.

Optionally, at least one of the at least one first beam comprises a conductive medium to transmit electrical signals between the first electrode and an external circuit.

Optionally, the back plate further comprises: the second supporting part and the at least one second beam fixedly connect the second electrode with the second supporting part.

Optionally, at least one of the at least one second beam comprises a conductive medium to transmit electrical signals between the second electrode and an external circuit.

Furthermore, at least one first support structure is arranged between the first electrode and the second electrode, the first support structure penetrates through the sound hole of the diaphragm, and the first support structure is respectively abutted against the first electrode and the second electrode.

Optionally, the first support structure is composed of one of silicon nitride, silicon oxide, and a composite of silicon nitride and silicon oxide.

Optionally, the back plate further comprises: at least one back plate through hole, the at least one back plate through hole encircles the second electrode for reduce the squeeze film damping between the back plate and the vibrating diaphragm.

Optionally, in a direction perpendicular to the plane of the substrate, a dust-proof structure for protecting the second electrode is disposed on a side of the back plate away from the diaphragm.

Optionally, a third supporting body for supporting the dust-proof structure is arranged on one side of the back plate away from the diaphragm; the third support body is positioned at the edge of the back plate, so that the dustproof structure is suspended above the back plate.

Optionally, the edge of the acoustic wave conduction region is provided with a first baffle structure facing the second electrode, and a gap is formed between the first baffle structure and the second electrode.

Optionally, a second baffle structure facing the diaphragm is disposed at an edge of the second electrode, and a gap is formed between the second baffle structure and the diaphragm.

Optionally, the edge of the diaphragm is further provided with at least one annular protrusion, the annular protrusion is in a continuous annular shape or an interrupted annular shape, and the annular protrusion protrudes toward the back cavity or protrudes away from the back cavity to release stress of the diaphragm, wherein the at least one annular protrusion surrounds the sound wave conduction region.

Optionally, at least one gap structure is disposed at an edge of the diaphragm, so as to release stress of the diaphragm.

Optionally, the edge of the diaphragm is provided with a plurality of gap structures, and the plurality of gap structures are arranged in an annular shape.

According to another aspect of the present invention, there is also provided an electronic device including the microphone assembly according to any of the embodiments described above.

The microphone assembly and the electronic equipment provided by the invention can realize a differential capacitance scheme of a single diaphragm, and the performance of the microphone assembly is improved.

Furthermore, the back plate of the microphone assembly provided by the invention is provided with a large third hollow area, so that the squeeze film damping between the back plate and the vibrating diaphragm can be obviously reduced, in addition, a first supporting structure is also arranged between the first electrode and the second electrode, the first supporting structure is respectively abutted against the first electrode and the second electrode, the problems of second electrode shaking and second capacitor structure failure caused by insufficient supporting force of the second beam on the second electrode can be prevented, and the reliability of a microphone product is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other embodiments based on these drawings without creative efforts.

Fig. 1A is a perspective view of a microphone assembly according to an embodiment of the invention.

Fig. 1B is a schematic cross-sectional view of a portion of the microphone assembly of fig. 1A.

Fig. 1C is a schematic top view of a portion of the diaphragm in fig. 1A.

Fig. 1D is a schematic top view of a portion of the back plate of fig. 1A.

FIG. 1E is a schematic top view of a portion of the substrate of FIG. 1A.

Fig. 2 is a schematic partial sectional view of a microphone assembly according to another embodiment of the present invention.

Fig. 3A is a perspective view of a microphone assembly according to another embodiment of the invention.

Fig. 3B is a schematic top view of a portion of the back plate of fig. 3A.

Fig. 3C is a schematic top view of a portion of the substrate of fig. 3A.

Fig. 4 is a perspective view of a microphone assembly according to another embodiment of the present invention.

Fig. 5 to 6 are perspective views of a microphone assembly according to another embodiment of the present invention.

Fig. 7 is a perspective view of a microphone assembly according to another embodiment of the present invention.

Detailed Description

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following preferred embodiments are described in detail with reference to the accompanying drawings.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

The embodiment of the invention provides a microphone assembly which is a core component of an MEMS (micro-electromechanical systems) microphone and can be applied to electronic equipment with a sound acquisition function, such as a smart phone, a tablet personal computer, a recording pen, a hearing aid, vehicle-mounted equipment and the like. The embodiments of the present invention are not limited to the above application scenarios.

Example one

Fig. 1A is a schematic perspective view of a microphone assembly according to an embodiment of the present invention, and fig. 1B is a schematic partial sectional view of the microphone assembly in fig. 1A; FIG. 1C is a schematic diagram of a partial top view of the diaphragm of FIG. 1A; FIG. 1D is a schematic diagram of a partial top view of the back plate of FIG. 1A; FIG. 1E is a schematic top view of a portion of the substrate of FIG. 1A.

Referring to fig. 1A to fig. 1E, an embodiment of the invention provides a microphone assembly 1000 including a substrate 100, a diaphragm 200, and a backplate 300, wherein in a direction perpendicular to a plane of the substrate 100, the diaphragm 200 is located between the substrate 100 and the backplate 300; the diaphragm 200 has a sound wave conducting region 211, and at least one sound hole 212 penetrating the diaphragm 200 in the thickness direction is formed in the sound wave conducting region 211 to transmit sound waves from an external space; a partial area of the substrate 100 constitutes a first electrode 110, and the first electrode 110 has at least one first hollow area 118; a partial region of the back plate 300 forms a second electrode 310, and the second electrode 310 has at least one second hollow region 318; the acoustic wave conducting region 211 of the diaphragm 200 constitutes a third electrode 213; wherein, in a direction perpendicular to the plane of the substrate 100, the projections of the first electrode 110, the third electrode 213 and the second electrode 310 overlap; the substrate 100 further has at least one fourth hollow area 130, and the at least one fourth hollow area 130 surrounds the first electrode 110 to form a back cavity 131.

Preferably, the at least one fourth hollow region 130 is an annular back cavity 131, so that the space of the annular back cavity 131 is large enough to reduce the surface vibration of the diaphragm 200 caused by the reflected wave, thereby improving the sensitivity and accuracy of the detection of the electric signal of the microphone.

In the embodiment of the present invention, the diaphragm 200 includes a vibration region 210 and a support region 220, the vibration region 210 includes the acoustic wave conduction region 211, preferably, the acoustic wave conduction region 211 is located at the center of the vibration region 210, and at least one acoustic hole 212 penetrating through the diaphragm 200 in the thickness direction is disposed on the acoustic wave conduction region 211 to transmit the acoustic wave from the external space; therefore, the acoustic wave propagation region 211 is not only an effective acoustic wave propagation region of the diaphragm 200, but also an effective vibration region of the diaphragm 200.

In a direction perpendicular to the plane of the substrate 100, the third electrode 213 formed by the acoustic wave conducting region 211 of the diaphragm 200 is located between the first electrode 110 and the second electrode 310, and projections of the first electrode 110, the acoustic wave conducting region 211, and the second electrode 310 overlap, so that the first electrode 110 and the third electrode 213 form a first capacitor structure of the microphone assembly 1000, the second electrode 310 and the third electrode 213 form a second capacitor structure of the microphone assembly 1000, the first capacitor structure and the second capacitor structure share the same diaphragm 200, and the amplitude change of the diaphragm 200 in the acoustic wave conducting region 211 causes capacitance values in the first capacitor structure and the second capacitor structure to change, thereby the first capacitor structure and the second capacitor structure can form a differential capacitor structure, thereby improving the performance of the signal-to-noise ratio of the microphone assembly 1000 to realize sound-electricity conversion; moreover, since the first electrode 110 is formed in a partial region of the substrate 100, the first electrode 110 does not need to be additionally disposed between the substrate 100 and the diaphragm 200 to form a differential capacitor structure, and thus, the volume of the microphone assembly 1000 can be reduced, thereby meeting the requirements of light weight and thin weight of electronic products.

And a first support 101 for supporting the diaphragm 200 is disposed on one side of the substrate 100 close to the diaphragm 200, and a second support 102 for supporting the back plate 300 is disposed on one side of the diaphragm 200 away from the substrate 100.

The sound pressure load during normal operation and the blowing load during abnormal operation are both loaded to the diaphragm 200 through the back chamber 131. The first supporting body 101 is supported between the substrate 100 and the diaphragm 200, and is configured to electrically isolate the diaphragm 200 from the substrate 100, and provide a support for the diaphragm 200, so that the diaphragm 200 (the third electrode 213) and the first electrode 110 are disposed oppositely and at an interval, and a first oscillation acoustic cavity for the diaphragm 200 to vibrate is formed between the first electrode 110 and the diaphragm 200. The second support 102 is supported between the diaphragm 200 and the back plate 300, and is configured to electrically isolate the back plate 300 from the diaphragm 200, and provide support for the back plate 300, so that the diaphragm 200 (the third electrode 213) and the second electrode 310 are disposed oppositely and at an interval, so that a second oscillation acoustic cavity for the diaphragm to vibrate is formed between the second electrode 310 and the diaphragm 200.

Illustratively, the first supporting body 101 is located at an edge of the substrate 100 to support the diaphragm 200, so that the diaphragm 200 is suspended above the first electrode 110 and is insulated and spaced from the first electrode 110, and the first electrode 110 and the acoustic wave conducting region 211 of the diaphragm 200 form a first variable capacitance; here, the diaphragm 200 includes a vibration region 210 and a support region 220, wherein the support region 220 suspends the diaphragm 200 above the first electrode 110 through the first support 101, and forms a gap with a preset distance from the first electrode 110. The second support 102 is located at an edge of the diaphragm 200 to support the back plate 300, so that the back plate 300 is suspended above the diaphragm 200 and is insulated and spaced from the diaphragm 200, and the second electrode 310 and the acoustic wave conduction region 211 of the diaphragm 200 form a second variable capacitor. Through the first variable capacitor and the second variable capacitor, the output electric signal can be increased, so that the signal-to-noise ratio of the microphone is improved.

As shown in fig. 1E, the substrate 100 further includes: a first support part 120, at least one first beam 133, the at least one first beam 133 fixedly connecting the first electrode 110 with the first support part 120. Specifically, the first electrode 110 is supported and fixed by at least one first beam 133 extending outward toward the periphery of the substrate 100, and the at least one first beam 133 is connected to the first supporting portion 120 to support and fix the first electrode 110; wherein at least one of the at least one first beam 133 comprises a conductive medium to enable transmission of an electrical signal between the first electrode 110 and an external circuit (not shown). Illustratively, in some embodiments of the present invention, the area of the substrate 100 where the first electrode 110 is located is made of a conductive material, and the area of the substrate 100 other than the first electrode 110 is made of a non-conductive material, and a conductive film layer, such as electroplated copper, may be formed on at least one of the at least one beam 133 to implement an external circuit to apply a first voltage signal to the first electrode 110. Illustratively, in other embodiments of the present invention, the substrate 100 is a semiconductor substrate, and the substrate 100 includes a semiconductor material layer, which may be doped such that at least a portion of the semiconductor material layer has a conductive property for preparing the first electrode 110. Specifically, the region of the substrate 100 where the first electrode 110 is located may be doped in a semiconductor material layer to form an N-type dopant or a P-type dopant, and at least one of the regions of the substrate 100 where the at least one beam 133 is located may be doped in the semiconductor material layer to form the N-type dopant or the P-type dopant, so as to enable an external circuit to apply a first voltage signal to the first electrode 110.

Illustratively, the first supporting part 120 is located at an edge region of the substrate 100, and the first supporting part 120 is used for supporting the diaphragm 200, the back plate 300, various conductive electrodes (not shown), and the like. Specifically, in a direction perpendicular to the plane of the substrate 100, a first support 101 is disposed on a side surface of the first support part 120 to support the diaphragm 200, and a second support 102 is disposed on a side surface of the diaphragm 200 away from the first support part 120 to support the back plate 300. The first support 101 and the second support 102 are insulating supports, and may be, for example, silicon oxide or silicon nitride. The thickness of the first support 101 and the second support 102 is between 2-3 um, for example, the thickness of the first support 101 and the second support 102 is around 2.5 um.

Further, in a direction perpendicular to the surface of the substrate 100, the projection of the second supporting body 102 and/or the projection of the first supporting body 101 are located within the projection range of the first supporting part 120, so that the first supporting part 120 can better bear the first supporting body 101 and the second supporting body 102. Preferably, in a direction perpendicular to the surface of the substrate 100, the projection of the second support 102 is located within the projection range of the first support 101.

As shown in fig. 1A-1B, in the embodiment of the present invention, at least one annular protrusion 215 is further disposed at the edge of the vibration region 210 near the support region 220, the annular protrusion 215 is in a continuous ring shape or an interrupted ring shape, and the annular protrusion 215 protrudes toward the back cavity 131 or protrudes away from the back cavity 131 to release the stress of the diaphragm 200, so as to improve the sensitivity of the microphone; wherein the at least one annular protrusion 215 surrounds the acoustic wave conducting region 211.

As shown in fig. 1D, for example, in the embodiment of the present invention, the back plate 300 further has at least one third hollow area 330, and the at least one third hollow area 330 surrounds the second electrode 310 to reduce squeeze film damping between the back plate 300 and the diaphragm 200. This is because, when the microphone is small in size, squeeze film damping is generated in the gaps between the second electrode 310 and the diaphragm 200 and between the first electrode 110 and the diaphragm 200, which may limit the frequency response bandwidth of the microphone, and therefore, at least one third hollow region 330 needs to be disposed on the backplate 300 to reduce the squeeze film damping. In addition, the at least one third hollow-out region 330 disposed on the back plate 300 can enable more sound pressure load (sound wave airflow) to be transmitted to the sound wave transmission region of the diaphragm 200, which can be used to increase the sensitivity of the microphone to the sound wave airflow and improve the performance of the microphone product.

For example, in the embodiment of the present invention, the first electrode 110 has only one first hollow-out region 118, the second electrode 310 has only one second hollow-out region 318, and in a direction perpendicular to the plane of the substrate 100, projections of the first hollow-out region 118 and the second hollow-out region 318 overlap.

Further, in the embodiment of the present invention, the first hollow area 118 of the first electrode 110 is located in the center of the first electrode 110, and the second hollow area 318 of the second electrode 310 is located in the center of the second electrode 310. This is because, the center of the diaphragm 200 is generally the area where the deformation of the diaphragm 200 occurs most, when the external acoustic airflow enters from the side of the substrate 100 away from the diaphragm 200, if the area directly facing the center of the diaphragm 200 is blocked, the external acoustic airflow can only diffract to the acoustic wave conducting area 211 on the side of the diaphragm 200 close to the back cavity 131 through the annular back cavity 131, so as to increase the effective vibration area of the center of the diaphragm 200 directly facing the acoustic airflow, so that the diaphragm 200 can maximally follow the acoustic airflow to generate displacement deformation, the first hollow area 118 of the first electrode 110 is located in the center of the first electrode 110 to increase the electrical signal of the differential capacitance structure, thereby increasing the signal-to-noise ratio of the microphone. Or, when the external acoustic airflow is coming from the side of the back plate 300 away from the diaphragm 200, if the area directly facing the center of the diaphragm 200 is blocked, the external acoustic airflow can only diffract to the acoustic wave conducting area 211 on the side of the diaphragm 200 close to the third hollow-out area 330 through the third hollow-out area 330, so as to increase the effective vibration area of the center of the diaphragm 200 directly facing the acoustic airflow, and enable the diaphragm 200 to generate displacement deformation to the maximum extent following the acoustic airflow, the second hollow-out area 318 of the second electrode 310 is located at the center of the second electrode 310, so as to increase the electrical signal of the differential capacitor structure, thereby increasing the signal-to-noise ratio of the microphone. And overlapping the projection of the first hollow-out region 118 and the projection of the second hollow-out region 318 in a direction perpendicular to the plane of the substrate 100 can also facilitate displacement deformation of the diaphragm 200.

Illustratively, as shown in fig. 2, in further embodiments of the present invention, at least one gap structure 214 is disposed at an edge of the diaphragm 200 near the support region 220 to release stress of the diaphragm, thereby improving sensitivity of the microphone. Optionally, a plurality of gap structures 214 are disposed at the edge of the diaphragm 200 near the support region 220, and the plurality of gap structures 214 are arranged in a ring shape. And the edge of the vibration region 210 may be distributed with pores (not shown) according to design requirements, where the pores are set for a release process during wet etching when generated, for example, an insulating film layer below the diaphragm 200 is etched away by using a solution release method, so as to obtain the insulating first support 101 and the air gap. And this hole still can be used for balancing inside and outside atmospheric pressure to reduce the atmospheric pressure impact that receives in the vibrating process of vibrating diaphragm 200, make vibrating diaphragm 200 in the vibrating process, the high-pressure draught part that produces in first vibration acoustic cavity and second vibration acoustic cavity discharges the exterior space through the hole, improves acoustic effect, and can prevent in the vibrating process, because the vibration that the pressure differential of vibrating diaphragm 200 both sides leads to causes the problem that vibrating diaphragm 200 damages.

In the embodiment of the present invention, as shown in fig. 1D, the back plate 300 further includes: a second supporting portion 320, at least one second beam 303, wherein the at least one second beam 303 fixedly connects the second electrode 310 and the second supporting portion 320. Further, the at least one second beam 303 is electrically connected to the second electrode 310, and at least one of the at least one second beam 303 includes a conductive medium to transmit an electrical signal between the second electrode 310 and an external circuit.

In the embodiment of the present invention, in order to reduce squeeze film damping between the back plate 300 and the diaphragm 200, the back plate 300 has at least one third hollow area 330 surrounding the second electrode 310, and the second electrode 310 is fixedly connected to the second supporting portion 320 through the at least one second beam 303, but since the second beam 303 has insufficient supporting force when supporting and fixing the second electrode 310, a problem of shaking of the second electrode 310 may occur in the microphone assembly during operation, a problem of shaking of the second electrode 310 may be prevented in order to prevent shaking of the second electrode 310 or a problem of failure of the second capacitor structure due to insufficient supporting strength of the second electrode 310. Optionally, as shown in fig. 1A, fig. 1B and fig. 2, in an embodiment of the present invention, at least one first supporting structure 112 is disposed between the first electrode 110 and the second electrode 310, the first supporting structure 112 is disposed in the acoustic hole 212 of the diaphragm 200, and the first supporting structure 112 is abutted to the first electrode 110 and the second electrode 310 respectively, so as to support and fix the second electrode 310, prevent the second electrode 310 from shaking and insufficient supporting strength, and thus achieve fixing the relative position between the first electrode 110 and the second electrode 310. And the first supporting structure 112 is made of one of silicon nitride, silicon oxide and a composite material of silicon nitride and silicon oxide to ensure electrical insulation between the first electrode 110 and the second electrode 310.

Illustratively, as shown in fig. 1B and fig. 2, at least one first supporting structure 112 is formed on a side surface of the first electrode 110 facing the second electrode 310, the first supporting structure 112 is inserted into the sound hole 212 of the diaphragm 200, the first supporting structure 112 abuts against the second electrode 310 to support and fix the second electrode 310, and problems of jitter and insufficient supporting strength of the second electrode 310 are prevented, so that relative position fixation between the first electrode 110 and the second electrode 310 is achieved. Of course, in other embodiments of the present invention, at least one first supporting structure 112 may also be formed on a side surface of the second electrode 310 facing the first electrode 110, which is not described herein again.

Here, the upper and lower pole plates (the first electrode 110 and the second electrode 310) of the microphone assembly with the differential capacitor structure provided by the embodiment of the present invention are fixed, at this time, the upper and lower pole plates (the first electrode 110 and the second electrode 310) may be referred to as "static pole plates", and the middle diaphragm 200 is referred to as "dynamic pole plate", when a sound pressure load is applied to the microphone assembly, the middle diaphragm 200 vibrates therewith, so that the capacitance C between the upper and lower pole plates (between the first electrode 110 and the second electrode 310) is changed, and it is known that the C-d characteristic is a curve.

Exemplarily, in the microphone assembly with the differential capacitor structure, the initial gap of the first capacitor structure C1 is d0, the initial gap of the second capacitor structure C2 is also d0, the initial capacitance size of the first capacitor structure C1 is C0, the initial capacitance size of the second capacitor structure C2 is C0, when the moving distance of the diaphragm 200 is Dd, the gap d1 of the first capacitor structure C1 becomes d0-Dd, and the gap d2 of the second capacitor structure C2 becomes d0+ Dd, that is, Δ d = Dd. The capacitance variation of the first capacitance structure C1 is Δ C, and the capacitance variation of the second capacitance structure C2 is Δ C. When Dd/d0 is less than or equal to 1, a similar linear relationship is obtained:

。

the sensitivity of the differential capacitor structure is as follows:

。

therefore, in the microphone assembly with the differential capacitor structure, the sensitivity of the microphone is improved by nearly one time, and the relative nonlinear error can be reduced by one order of magnitude, so that the error caused by the environmental influence can be reduced to the maximum extent.

Example two

Fig. 3A is a schematic perspective view of a microphone assembly according to another embodiment of the invention, fig. 3B is a schematic partial top view structure of the backplate in fig. 3A, and fig. 3C is a schematic partial top view structure of the substrate in fig. 3A.

Referring to fig. 3A to 3C, the first electrode 110 has at least two first hollow areas 118 and/or the second electrode 310 has at least two second hollow areas 318, and projections of areas formed by all the first hollow areas 118 and areas formed by all the second hollow areas 318 at least partially overlap in a direction perpendicular to a plane of the substrate 100.

As can be seen in fig. 3A to 3C, the second electrode 310 has more than 2 second hollow-out regions 318, and similarly, the first electrode 110 may also have more than 2 first hollow-out regions 118, by the above arrangement, not only the effective vibration area of the center of the diaphragm 200 directly facing the acoustic airflow can be increased, but also the acoustic airflow can be dispersed to uniformly act on the acoustic conduction region 211 on the diaphragm 200, so that the acoustic conduction region 211 of the diaphragm 200 can be uniformly deformed, and the sensitivity and accuracy of the microphone detection can be improved.

EXAMPLE III

As shown in fig. 4, the microphone assembly in fig. 4 differs from that in fig. 1A, for example, in that: the backplate 300 in fig. 1A has at least one third hollow-out region 330, and the at least one third hollow-out region 330 surrounds the second electrode 310 to reduce squeeze film damping between the backplate 300 and the diaphragm 200. The backplate 300 in fig. 4 includes at least one backplate through hole 340, and the at least one backplate through hole 340 surrounds the second electrode 310 to reduce squeeze film damping between the backplate 300 and the diaphragm 200. The function of the back plate through hole 340 in fig. 4 is similar to that of the third hollow area 330, and is not described again here. However, compared to the method of providing the large third hollow area 330 in fig. 1A, the method of providing the back plate through hole 340 can significantly improve the mechanical reliability of the second electrode 310, and can prevent the second electrode 310 from shaking or failing due to insufficient supporting force. In addition, the back plate through hole 340 may also serve as a release hole for removing the insulating film layer between the back plate 300 and the diaphragm 200 by a solution release method.

Example four

As shown in fig. 5, the microphone assembly in fig. 5 differs from fig. 1A exemplarily in that: the edge of the acoustic wave conducting region 211 is provided with a first baffle structure 201 facing the second electrode 310, and a gap is formed between the first baffle structure 201 and the second electrode 310. Specifically, in the embodiment of the present invention, the first baffle structure 201 may form a continuous or discontinuous ring shape on the edge of the sound wave conducting region 211, and the first baffle structure 201 is made of an insulating material, and on one hand, has a limiting function, and can prevent the diaphragm 200 from being adhered to the back plate 300 in a wet environment, and also has a dustproof function, and can prevent dust entering through at least one third hollow-out region 330 of the back plate 300 from polluting the sound hole 212 in the sound wave conducting region 211, thereby affecting the sensitivity and accuracy of microphone electric signal detection.

As shown in fig. 6, the microphone assembly in fig. 6 differs from that in fig. 1A, for example, in that: the edge of the second electrode 310 is provided with a second baffle structure 301 facing the diaphragm 200, and a gap is formed between the second baffle structure 301 and the diaphragm 200. Specifically, in the embodiment of the present invention, the second baffle structure 301 may form a continuous or discontinuous ring shape on the edge of the second electrode 310, and the second baffle structure 301 is made of an insulating material, so as to have a limiting function on one hand, prevent the diaphragm 200 from being adhered to the back plate 300 in a wet environment, and also have a dustproof function on the other hand, and prevent dust entering through the at least one third hollow-out region 330 of the back plate 300 from polluting the sound hole 212 in the sound wave conducting region 211, thereby affecting the sensitivity and accuracy of detecting the microphone electrical signal.

EXAMPLE five

As shown in fig. 7, the microphone assembly in fig. 7 differs from fig. 1A, 3A, 4-6 exemplarily in that: in fig. 7, in a direction perpendicular to the plane of the substrate 100, a dust-proof structure 400 for protecting the second electrode 310 is disposed on a side of the back plate 300 away from the diaphragm 200, so as to prevent dust in the environment from entering the sound hole 212 in the sound wave conducting region 211 through the third hollow-out region 330 on the back plate 300 shown in fig. 1A, 3A, 5, 6, and 7 or the back plate through hole 340 on the back plate 300 shown in fig. 4, or through the second hollow-out region 318 on the second electrode 310.

Optionally, in order not to affect the transmission of the sound pressure load, a third supporting body 103 for supporting the dust-proof structure 400 is disposed on a side of the back plate 300 away from the diaphragm 200; the third supporting body 103 is located at the edge of the back plate 300, so that the dustproof structure 400 is suspended above the back plate 300. Preferably, the dust-proof structure 400 is detachably or movably installed above the back plate 300 to prevent the transmission of the sound pressure load from being blocked.

The invention also provides an electronic device comprising any one of the microphone assemblies described above. The microphone assembly can be applied to various electronic devices, such as smart phones, tablet computers, recording pens, hearing aids, vehicle-mounted devices and the like.

Therefore, the microphone assembly and the electronic device provided by the embodiment of the invention not only can obviously improve the signal-to-noise ratio of the microphone, but also have small volume. The microphone assembly comprises a substrate, a vibrating diaphragm and a back plate, wherein the vibrating diaphragm is positioned between the substrate and the back plate in a direction perpendicular to the plane of the substrate; at least one sound hole penetrating through the diaphragm in the thickness direction is formed in the sound wave conduction area of the diaphragm, a partial area of the substrate forms a first electrode, and the first electrode is provided with at least one first hollow-out area; a partial area of the back plate forms a second electrode, and the second electrode is provided with at least one second hollow-out area; the sound wave conduction area of the diaphragm forms a third electrode; in a direction perpendicular to the plane of the substrate, projections of the first electrode, the third electrode and the second electrode overlap. The technical scheme provided by the invention realizes the differential capacitance scheme of the single diaphragm and improves the performance of the microphone assembly.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A microphone assembly is characterized by comprising a substrate, a vibrating diaphragm and a back plate, wherein the vibrating diaphragm is positioned between the substrate and the back plate in a direction perpendicular to the plane of the substrate;

the diaphragm is provided with a sound wave conduction area, and at least one sound hole penetrating through the diaphragm in the thickness direction is formed in the sound wave conduction area so as to transmit sound waves from an external space;

a partial area of the substrate forms a first electrode, and the first electrode is provided with at least one first hollow area;

a partial area of the back plate forms a second electrode, and the second electrode is provided with at least one second hollow area;

the diaphragm constitutes a third electrode;

in a direction perpendicular to a plane of the substrate, projections of the first electrode, the third electrode and the second electrode are overlapped, the substrate further has at least one fourth hollowed-out area, the at least one fourth hollowed-out area surrounds the first electrode to form a back cavity, and the depth of the back cavity is equal to the thickness of the substrate.

2. The microphone assembly of claim 1, wherein the first electrode has only one of the first hollowed-out regions, the second electrode has only one of the second hollowed-out regions, and projections of the first hollowed-out region and the second hollowed-out region overlap in a direction perpendicular to a plane of the substrate.

3. The microphone assembly of claim 2 wherein the first hollowed out area of the first electrode is located in the center of the first electrode and the second hollowed out area of the second electrode is located in the center of the second electrode.

4. The microphone assembly of claim 1, wherein the first electrode has at least two first hollowed-out regions and/or the second electrode has at least two second hollowed-out regions, and projections of all the first hollowed-out regions and all the second hollowed-out regions at least partially overlap in a direction perpendicular to a plane in which the substrate is located.

5. The microphone assembly of any of claims 1-4, wherein the backplate further has at least one third hollowed-out region surrounding the second electrode.

6. The microphone assembly of claim 5,

a first supporting body for supporting the vibrating diaphragm is arranged on one side, close to the vibrating diaphragm, of the substrate, and a second supporting body for supporting the back plate is arranged on one side, far away from the substrate, of the vibrating diaphragm;

the first support body is positioned at the edge of the substrate, so that the vibrating diaphragm is suspended above the first electrode, and the first electrode and the vibrating diaphragm form a first variable capacitor;

the second support body is located at the edge of the vibrating diaphragm, so that the back plate is suspended above the vibrating diaphragm, and the second electrode and the vibrating diaphragm form a second variable capacitor.

7. The microphone assembly of claim 6, wherein the substrate further comprises:

the first support part is used for supporting the first support part,

at least one first beam fixedly connecting the first electrode with the first support.

8. The microphone assembly of claim 7,

at least one of the at least one first beam includes a conductive medium to transmit electrical signals between the first electrode and an external circuit.

9. The microphone assembly of claim 8, wherein the backplate further comprises:

a second supporting part for supporting the first supporting part,

at least one second beam fixedly connecting the second electrode with the second support.

10. The microphone assembly of claim 9 wherein at least one of the at least one second beam comprises a conductive medium to transmit electrical signals between the second electrode and an external circuit.

11. The microphone assembly of claim 5,

at least one first supporting structure is arranged between the first electrode and the second electrode, the first supporting structure penetrates through the sound hole of the vibrating diaphragm, and the first supporting structure is respectively abutted against the first electrode and the second electrode.

12. The microphone assembly of claim 11,

the first support structure is composed of one of silicon nitride, silicon oxide, and a composite material of silicon nitride and silicon oxide.

13. The microphone assembly of claim 5, wherein the backplate further comprises:

at least one back plate through hole surrounding the second electrode.

14. The microphone assembly of claim 1,

and in the direction vertical to the plane of the substrate, a dustproof structure for protecting the second electrode is arranged on one side of the back plate, which is far away from the vibrating diaphragm.

15. The microphone assembly of claim 14,

a third supporting body for supporting the dustproof structure is arranged on one side, away from the vibrating diaphragm, of the back plate;

the third support body is positioned at the edge of the back plate, so that the dustproof structure is suspended above the back plate.

16. The microphone assembly of claim 5,

the edge of the acoustic wave conduction region is provided with a first baffle structure facing the second electrode, and a gap is formed between the first baffle structure and the second electrode.

17. The microphone assembly of claim 5,

the edge of the second electrode is provided with a second baffle structure facing the vibrating diaphragm, and a gap is reserved between the second baffle structure and the vibrating diaphragm.

18. The microphone assembly of claim 5,

the edge of the diaphragm is also provided with at least one annular bulge part, the annular bulge part is in a continuous annular shape or an interrupted annular shape, and the annular bulge part is bulged towards the direction of the back cavity or is bulged towards the direction deviating from the back cavity, wherein the at least one annular bulge part surrounds the sound wave conduction region.

19. The microphone assembly of claim 5,

the edge of the diaphragm is provided with at least one gap structure.

20. The microphone assembly of claim 19,

the edge of vibrating diaphragm is equipped with a plurality of gap structures, a plurality of gap structures are the annular and arrange.

21. An electronic device comprising a microphone assembly as claimed in any one of claims 1 to 20.