CN219145557U

CN219145557U - Microphone structure and electronic equipment

Info

Publication number: CN219145557U
Application number: CN202320139562.9U
Authority: CN
Inventors: 华超
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2023-02-01
Filing date: 2023-02-01
Publication date: 2023-06-06
Anticipated expiration: 2033-02-01

Abstract

The utility model provides a microphone structure and electronic equipment, which aim at reducing the manufacturing process of an acoustic-electric conversion structure and reducing the overall height of the acoustic-electric conversion structure at the same time by arranging a concave part on the first surface of a substrate and enabling a vibrating diaphragm to be contacted with the first surface of the substrate so that the vibrating diaphragm is suspended above the concave part and forms a cavity with the surface of the concave part, wherein the cavity can be used as an oscillation acoustic cavity of the vibrating diaphragm, thereby omitting an insulator structure such as silicon oxide and the like arranged between the substrate and the vibrating diaphragm and used for supporting and fixing the vibrating diaphragm.

Description

Microphone structure and electronic equipment

Technical Field

The present utility model relates to the field of microphone technologies, and in particular, to a microphone structure and an electronic device.

Background

MEMS microphones formed using microelectromechanical systems (Micro-Electro-Mechanical System) are widely used due to their potential advantages in terms of miniaturization, performance, reliability, environmental durability, cost, and mass production capability.

In the package structure of the MEMS microphone, the MEMS microphone chip and the ASIC (Application Specific Integrated Circuit ) chip are directly attached to a PCB (Printed Circuit Board, printed circuit board) board for packaging. The MEMS microphone chip comprises a substrate, a vibrating diaphragm and a back polar plate, wherein the substrate is provided with a back cavity penetrating through the substrate in the thickness direction, a sensing cavity is formed between the vibrating diaphragm and the back polar plate, and the vibrating diaphragm and the back polar plate form a variable capacitance.

For the microphone structure of bottom sound, when external sound wave arrives on the vibrating diaphragm through the back cavity from the sound inlet hole of base plate (PCB board), can arouse the vibrating diaphragm and vibrate from top to bottom, lead to the atmospheric pressure in the sensing cavity to receive the extrusion and form resonance, because at the in-process of resonance, the noise is increased gradually, can cause the interference to reduced the degree of accuracy and the sensitivity that MEMS microphone detected, influenced output signal's signal to noise ratio.

Accordingly, improvements in the art are needed.

Disclosure of Invention

The utility model aims to at least solve one of the technical problems in the prior art and provides a microphone structure and electronic equipment.

The utility model adopts the following technical scheme:

according to an aspect of the present utility model, there is provided a microphone structure including a substrate, a housing, and an electroacoustic conversion structure, the housing and the substrate being fixedly connected to form a cavity, the electroacoustic conversion structure being fixedly connected to a side of the substrate facing the housing and being located in the cavity; the sound-electricity conversion structure comprises a substrate, and a vibrating diaphragm and a back electrode plate which are sequentially arranged on the substrate in a lamination mode, wherein the substrate is provided with a first surface which is in contact with the vibrating diaphragm and supports the vibrating diaphragm, the substrate is provided with a concave part on the first surface, a cavity is formed between the surface of the concave part and the surface of one side of the vibrating diaphragm, which faces the first surface, of the vibrating diaphragm, the substrate is provided with a first hollowed-out area penetrating through the surface of the concave part and the second surface of the substrate in the thickness direction, the first hollowed-out area is communicated with the cavity to form a back cavity, and the second surface is arranged opposite to the first surface; the substrate is provided with a sound inlet hole penetrating through the substrate in the thickness direction, and the back cavity of the sound-electricity conversion structure is opposite to the sound inlet hole; the diameter of the first hollowed-out area is larger than that of the sound inlet hole.

Optionally, in a thickness direction of the substrate, a projection shape of the concave portion on the substrate is annular or rectangular.

Further, in the thickness direction of the substrate, the depth of the recess is greater than or equal to 2 μm.

Further, in the thickness direction of the substrate, the orthographic projection of the first hollowed-out area on the substrate is located in the orthographic projection range of the concave part on the substrate.

Optionally, an adhesive is disposed on the second surface of the substrate having the back cavity, and the acoustoelectric conversion structure is fixedly connected with the substrate through the adhesive.

Further, a first support body for supporting the back electrode plate is arranged on one side, away from the substrate, of the vibrating diaphragm, the first support body is located at the edge of the vibrating diaphragm, so that the back electrode plate is suspended above the vibrating diaphragm, and a variable capacitor is formed by the back electrode plate and the vibrating diaphragm.

Further, at least one diaphragm through hole penetrating through the diaphragm in the thickness direction is formed in the diaphragm, and the at least one diaphragm through hole is formed in the edge of the vibration sensitive area of the diaphragm.

Further, at least one back plate through hole penetrating through the back plate in the thickness direction is formed in the back plate.

Further, the microphone structure further comprises a signal processing circuit located in the cavity, and the signal processing circuit is electrically connected with the acousto-electric conversion structure and the substrate through wires respectively.

According to another aspect of the present utility model, there is also provided an electronic device including any of the microphone structures described above.

The microphone structure and the electronic equipment provided by the utility model aim at reducing the manufacturing process of the sound-electricity conversion structure, and simultaneously reducing the overall height of the sound-electricity conversion structure, thereby reducing the manufacturing cost by arranging the insulator structure, such as silicon oxide and the like, between the substrate and the vibrating diaphragm, and omitting the insulator structure, such as silicon oxide and the like, for supporting and fixing the vibrating diaphragm.

Further, not only can make the vibrating diaphragm directly fixed and suspend in the top of back of body chamber, when guaranteeing the effective vibrating area of vibrating diaphragm, can also reduce the volume of the back of body chamber of sound wave sensing structure. Because the resonance frequency is inversely proportional to the volume of the back cavity, the resonance frequency is increased when the volume of the back cavity is reduced, so that the high frequency is upturned, the noise is reduced, and the problem of influence on useful signals caused by gradual increase of the noise in the resonance process of the vibrating diaphragm in the sensing cavity is solved, thereby improving the signal to noise ratio of a microphone product.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other embodiments may be obtained according to these drawings without inventive effort to a person skilled in the art.

Fig. 1 is a schematic diagram of a microphone structure according to an embodiment of the present utility model;

FIG. 2 is a schematic top view of a substrate of an electroacoustic transducer structure of the microphone structure provided in FIG. 1;

fig. 3 is a schematic top view of still another structure of the substrate of the acoustic-electric conversion structure in the microphone structure provided in fig. 1.

Detailed Description

The foregoing description is only an overview of the present utility model, and is intended to be implemented in accordance with the teachings of the present utility model, as well as the preferred embodiments thereof, together with the following detailed description of the utility model, given by way of illustration only, together with the accompanying drawings.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically connected, electrically connected or can be communicated with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The embodiment of the utility model provides a microphone structure, which is a core component of an MEMS microphone, and can be applied to electronic equipment with a sound collection function, such as a smart phone, a tablet personal computer, a recording pen, a hearing aid, vehicle-mounted equipment and the like. The embodiment of the utility model is not limited to the application scenario.

Example 1

Fig. 1 is a schematic diagram of a microphone structure according to an embodiment of the present utility model, and fig. 2 is a schematic diagram of a top view of a substrate of an electroacoustic conversion structure in the microphone structure provided in fig. 1; fig. 3 is a schematic top view of still another structure of the substrate of the acoustic-electric conversion structure in the microphone structure provided in fig. 1.

Referring to fig. 1-3, an embodiment of the present utility model provides a microphone structure 1000 including a substrate 100, a housing 200, and an electroacoustic conversion structure 300, wherein the housing 200 and the substrate 100 are fixedly connected to form a cavity 201, and the electroacoustic conversion structure 300 is fixedly connected to a side of the substrate 100 facing the housing 200 and is located in the cavity 201; the electroacoustic conversion structure 300 comprises a substrate 310 and a diaphragm 320 and a back plate 330 which are sequentially arranged on the substrate 310 in a stacked manner, wherein the substrate 310 is provided with a first surface 310a which is in contact with the diaphragm 320 and supports the diaphragm 320, the substrate 310 is provided with a concave part 312 on the first surface 310a, a cavity 50 is formed by the surface of the concave part 312 and the surface of one side of the diaphragm 320 facing the first surface 310a, the substrate 310 is provided with a first hollowed-out area 313 penetrating through the bottom surface of the concave part 312 and the second surface 310b of the substrate 310 in the thickness direction, the first hollowed-out area 313 is communicated with the cavity 50 to form a back cavity 311, and the second surface 310b is arranged opposite to the first surface 310 a; the substrate 100 is provided with a sound inlet 60 penetrating through the substrate 100 in the thickness direction, and the back cavity 311 of the sound-to-electricity conversion structure 300 is opposite to the sound inlet 60; the diameter of the first hollowed-out area 313 is larger than the diameter of the sound inlet 60.

Specifically, in some embodiments, the acousto-electric conversion structure 300 includes a MEMS microphone chip for acousto-electric conversion.

For example, when the substrate 310 is made of a silicon material, an insulating layer may be disposed on the first surface 310a of the substrate 310 except for the recess 312 to electrically isolate the diaphragm 320, so as to prevent the electrical signal on the diaphragm 320 from being disturbed, that is, it is also possible to implement a technical scheme that the substrate 310 with the recess 312 is in spaced contact with the diaphragm 320.

In order to ensure that the sound-to-electricity conversion structure 300 can sense the sound signal transmitted from the outside at the first time, the position of the first hollow area 313 of the sound-to-electricity conversion structure 300 needs to correspond to the position of the sound inlet 60 on the substrate 100, and the orthographic projection of the first hollow area 313 on the substrate is circular, and the diameter of the first hollow area 313 is larger than the diameter of the sound inlet 60, so that the sound inlet 60 is not blocked, so as to avoid the influence on the pick-up capability of the microphone structure.

By adopting the technical scheme provided by the utility model, the first surface of the substrate is provided with the concave part, the vibrating diaphragm is contacted with the first surface of the substrate, so that the vibrating diaphragm is suspended above the concave part and forms a cavity with the surface of the concave part, and the cavity can be used as an oscillation acoustic cavity of the vibrating diaphragm, thereby omitting an insulator structure, such as silicon oxide and the like, arranged between the substrate and the vibrating diaphragm for supporting and fixing the vibrating diaphragm, reducing the manufacturing process of the acoustic-electric conversion structure, reducing the overall height of the acoustic-electric conversion structure, and reducing the manufacturing cost.

Further, as shown in fig. 2 and 3, in the thickness direction of the substrate 310, the projection shape of the recess 312 on the substrate 310 is annular or rectangular. The shape and size of the recess 312 affects the area of the effective vibration area of the resulting diaphragm 320.

Further, in the thickness direction of the substrate 310, the depth of the recess 312 is greater than or equal to 2 μm. For example, 2-3 μm, and illustratively, 2.5 μm, to form an oscillating acoustic cavity sufficient for oscillation of the diaphragm 320.

Specifically, a recess 312 is formed by performing a first etching on a first surface 310a of the substrate 310, and then performing a second etching on the second surface 310b of the substrate 310 having the recess 312 to form the first hollowed-out region 313 penetrating through the second surface 310b of the substrate 310 and a bottom surface of the recess 312 in a thickness direction; in the thickness direction of the substrate 310, the orthographic projection of the first hollowed-out area 313 on the substrate 310 is located within the orthographic projection range of the recess 312 on the substrate 310.

By adopting the technical scheme provided by the embodiment, the vibrating diaphragm can be directly fixed and suspended above the back cavity, the area of the effective vibrating area of the vibrating diaphragm is ensured, and the volume of the back cavity of the sound wave sensing structure can be reduced. Because the resonance frequency is inversely proportional to the volume of the back cavity, the resonance frequency is increased when the volume of the back cavity is reduced, so that the high frequency is upturned, the noise is reduced, and the problem of influence on useful signals caused by gradual increase of the noise in the resonance process of the vibrating diaphragm in the sensing cavity is solved, thereby improving the signal to noise ratio of a microphone product.

In the process of fabricating the acoustic wave sensing structure, illustratively, a silicon oxide insulating layer is grown (or filled) in the recess 312, then a polysilicon film layer is grown to form the diaphragm 320, and then the diaphragm is grown layer by layer according to the MEMS semiconductor process, finally the back cavity 311 is etched by using a deep silicon etching process, the volume of the back cavity 311 is reduced by reducing the etched size, the silicon oxide layer in the recess 312 of the substrate 310 is dissolved by using a solution through a release process, and finally an L-shaped substrate structure is formed, as shown in fig. 1, the volume of the back cavity 311 is reduced, and thus the resonance frequency is increased, so that the noise integral within 20Hz to 20KHz is reduced, and the signal to noise ratio is increased.

Optionally, in an embodiment of the present utility model, an adhesive is disposed on the second surface 310b of the substrate 310 having the back cavity 311, and the acoustoelectric conversion structure 300 is fixedly connected to the substrate 100 through the adhesive. At this time, since the diameter of the first hollowed-out area 313 is larger than the diameter of the sound inlet 60 on the substrate 100, the sound inlet 60 is not blocked, so as to avoid the influence on the pick-up capability of the microphone structure, and since the orthographic projection of the first hollowed-out area 313 on the substrate 310 is located within the orthographic projection range of the recess 312 on the substrate 310, the adhesion area of the electroacoustic conversion structure 300 and the substrate 100 is correspondingly increased, and the fixing strength is improved.

It should be appreciated that in other embodiments, the acoustoelectric conversion structure 300 is fixedly coupled to the substrate 100 by a coupling agent.

Further, a first supporting body 340 for supporting the back electrode plate 330 is disposed on a side of the diaphragm 320 away from the substrate 310, and the first supporting body 340 is located at an edge of the diaphragm 320, so that the back electrode plate 330 is suspended above the diaphragm 320, and the back electrode plate 330 and the diaphragm 320 form a variable capacitor.

The first supporting body 340 is disposed between the diaphragm 320 and the back plate 330, and is used for electrically isolating the diaphragm 320 and the back plate 330, and in the thickness direction of the substrate 310, the orthographic projection of the first supporting body 340 is located around the diaphragm 320, and is used for supporting and fixing the diaphragm 320. The material of the first support 340 may be silicon oxide or silicon nitride, etc. The thickness of the first support 340 is between 2 and 3 μm, for example, around 2.5 μm. The back plate 330 and the diaphragm 320 are arranged opposite to each other at intervals, so that an oscillating acoustic cavity for vibrating the diaphragm 320 is formed between the back plate 330 and the diaphragm 320. When the MEMS microphone chip works, a plate capacitor is formed between the diaphragm 320 and the back plate 330, and when external sound waves act on the diaphragm 320, an oscillation sensitive area of the diaphragm 320 is caused to vibrate up and down, so that air pressure in the back cavity 311 is extruded to cause resonance. Because the resonance frequency is inversely proportional to the volume of the back cavity 311, the resonance frequency becomes larger when the volume of the back cavity 311 becomes smaller, so that the high frequency is upturned, the noise becomes smaller, and the problem of influence on the useful signal caused by gradual increase of the noise in the resonance process of the diaphragm 320 in the sensing cavity is solved, thereby improving the signal-to-noise ratio of the microphone product.

Further, at least one diaphragm through hole 321 penetrating the diaphragm 320 in the thickness direction is disposed on the diaphragm 320, and the at least one diaphragm through hole 321 is disposed at the edge of the vibration sensitive area of the diaphragm 320. The at least one diaphragm through hole 321 is used as a release hole for releasing stress on the diaphragm 320, so as to reduce the phenomenon of diaphragm breakage, and the release hole can be used in a solution release process.

Further, at least one back plate through hole 331 penetrating the back plate 330 in the thickness direction is provided on the back plate 330. The at least one backplate through hole 331 serves as an acoustic hole to transmit acoustic airflow for reducing the damping of the diaphragm between the backplate 330 and the diaphragm 320. This is because, when the size of the microphone is small, the gap between the backplate 330 and the diaphragm 320 may generate a damping force, which may limit the bandwidth of the microphone, and thus, at least one backplate through hole 331 needs to be provided in the backplate 330 to reduce the damping force.

Further, in the above embodiment, the microphone structure further includes a signal processing circuit 400 located in the cavity 201, and the signal processing circuit 400 is electrically connected to the electroacoustic conversion structure 300 and the substrate 100 through wires, respectively.

Specifically, the signal processing circuit 400 is an ASIC (Application Specific Integrated Circuit ) chip for signal amplification.

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

Therefore, according to the microphone structure and the electronic device provided by the embodiment of the utility model, at least one protruding part is arranged on the side, facing the shell, of the substrate so as to reduce the volume of the back cavity of the sound-electricity conversion structure, and the resonance frequency is increased when the volume of the back cavity is reduced because the resonance frequency is inversely proportional to the volume of the back cavity, so that the high frequency is upturned, the noise is reduced, and the problem of influence on interference of useful signals caused by gradual increase of the noise in the resonance process of the vibrating diaphragm in the sensing cavity is solved, so that the signal-to-noise ratio of a microphone product is improved.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; although the utility model 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 scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims

1. The microphone structure is characterized by comprising a substrate, a shell and an acoustic-electric conversion structure, wherein the shell is fixedly connected with the substrate to form a cavity, and the acoustic-electric conversion structure is fixedly connected with one side of the substrate, facing the shell, and is positioned in the cavity;

the sound-electricity conversion structure comprises a substrate, and a vibrating diaphragm and a back electrode plate which are sequentially arranged on the substrate in a lamination mode, wherein the substrate is provided with a first surface which is in contact with the vibrating diaphragm and supports the vibrating diaphragm, the substrate is provided with a concave part on the first surface, a cavity is formed between the surface of the concave part and the surface of one side of the vibrating diaphragm, which faces the first surface, of the vibrating diaphragm, the substrate is provided with a first hollowed-out area penetrating through the surface of the concave part and the second surface of the substrate in the thickness direction, the first hollowed-out area is communicated with the cavity to form a back cavity, and the second surface is arranged opposite to the first surface;

the substrate is provided with a sound inlet hole penetrating through the substrate in the thickness direction, and the back cavity of the sound-electricity conversion structure is opposite to the sound inlet hole; the diameter of the first hollowed-out area is larger than that of the sound inlet hole.

2. A microphone structure as claimed in claim 1, characterized in that,

in the thickness direction of the substrate, the projection shape of the concave part on the substrate is annular or rectangular.

3. A microphone structure as claimed in claim 2, characterized in that,

the depth of the recess is greater than or equal to 2 μm in the thickness direction of the substrate.

4. A microphone structure as claimed in claim 1, characterized in that,

in the thickness direction of the substrate, the orthographic projection of the first hollowed-out area on the substrate is positioned in the orthographic projection range of the concave part on the substrate.

5. A microphone structure as claimed in claim 1, characterized in that,

and an adhesive is arranged on the second surface of the substrate with the back cavity, and the sound-electricity conversion structure is fixedly connected with the substrate through the adhesive.

6. A microphone structure as claimed in claim 1, characterized in that,

one side of the vibrating diaphragm away from the substrate is provided with a first support body for supporting the back electrode plate, and the first support body is positioned at the edge of the vibrating diaphragm, so that the back electrode plate is suspended above the vibrating diaphragm, and the back electrode plate and the vibrating diaphragm form a variable capacitor.

7. A microphone structure as claimed in claim 1, characterized in that,

the vibrating diaphragm is provided with at least one vibrating diaphragm through hole penetrating through the vibrating diaphragm in the thickness direction, and the at least one vibrating diaphragm through hole is arranged at the edge of the vibration sensitive area of the vibrating diaphragm.

8. A microphone structure as claimed in claim 1, characterized in that,

at least one back electrode plate through hole penetrating through the back electrode plate in the thickness direction is formed in the back electrode plate.

9. A microphone structure as claimed in claim 1, characterized in that,

the microphone structure also comprises a signal processing circuit positioned in the cavity, and the signal processing circuit is respectively and electrically connected with the acousto-electric conversion structure and the substrate through leads.

10. An electronic device, characterized in that it comprises a microphone arrangement according to any of claims 1-9.