CN107484051B

CN107484051B - MEMS microphone

Info

Publication number: CN107484051B
Application number: CN201710902582.6A
Authority: CN
Inventors: 张睿
Original assignee: AAC Acoustic Technologies Shenzhen Co Ltd
Current assignee: AAC Technologies Holdings Shenzhen Co Ltd
Priority date: 2017-09-29
Filing date: 2017-09-29
Publication date: 2021-04-09
Anticipated expiration: 2037-09-29
Also published as: CN107484051A

Abstract

The invention provides an MEMS microphone, which comprises a substrate with an acoustic cavity, a back plate fixed on the substrate and a vibrating membrane which is arranged opposite to the back plate at intervals to form a capacitance structure, wherein the back plate comprises a back plate and a fixed electrode; the vibrating diaphragm comprises an effective vibrating part and an ineffective vibrating part, the effective vibrating part comprises a vibrating main body which is arranged opposite to the sound cavity and a fixed arm which extends from the vibrating main body and is fixed on the base, and the vibrating main body and the part of the fixed arm opposite to the sound cavity form an effective vibrating area together; the ineffective vibration part is positioned between two adjacent fixed arms and is arranged at intervals with the effective vibration part, and at least part of the ineffective vibration part is fixed on the base; the fixed electrode and the effective vibration region have the same shape. Compared with the prior art, the MEMS microphone has better acoustic performance.

Description

MEMS microphone

Technical Field

The invention relates to the field of acoustoelectrics, in particular to an MEMS (micro-electromechanical system) microphone applied to portable electronic products.

Background

The development of communication technology has led to the increase of mobile phone users worldwide, and the demand of users for mobile phones has not only satisfied the call but also provided the high quality call effect, especially the development of current mobile multimedia technology, the call quality of mobile phones is more important, and the design of the microphone of mobile phones as the voice pickup device of mobile phones directly affects the call quality.

A microphone in the related art, in particular, a MEMS microphone includes a substrate having an acoustic cavity, a back plate fixed to the substrate, a fixed electrode fixed to the north plate, and a diaphragm fixed to the substrate and spaced apart from the back plate to form a capacitor structure. The vibrating diaphragm comprises an effective vibration area and a fixed area, wherein the effective vibration area is opposite to the sound cavity, and the fixed area extends from the effective vibration area and is fixed on the base.

However, in the related art MEMS microphone, the area of the fixed electrode is smaller than the effective vibration region of the diaphragm, so that the effective capacitance of the MEMS microphone is relatively small, resulting in low performance thereof.

Therefore, it is necessary to provide a new MEMS microphone to solve the above technical problems.

Disclosure of Invention

The invention aims to provide a MEMS microphone with excellent acoustic performance.

In order to achieve the above object, the present invention provides an MEMS microphone, which includes a substrate having an acoustic cavity, a back plate fixed on the substrate, and a diaphragm fixed on the substrate and spaced from the back plate to form a capacitor structure, wherein the back plate includes a back plate and a fixed electrode attached to the back plate and close to one side of the diaphragm; the vibrating diaphragm comprises an effective vibrating part and an ineffective vibrating part, the effective vibrating part comprises a vibrating main body which is arranged opposite to the sound cavity and a fixed arm which extends from the vibrating main body and is fixed on the substrate, and the vibrating main body and the part of the fixed arm opposite to the sound cavity form an effective vibrating area together; the ineffective vibration part is positioned between two adjacent fixed arms and is arranged at an interval with the effective vibration part, and at least part of the ineffective vibration part is fixed on the substrate; the MEMS microphone also comprises a supporting part fixed on the substrate, and the supporting part is of an annular structure and is arranged around the vibrating membrane; the ineffective vibration part comprises a fixed part fixed on the substrate and an extension part extending from the fixed part to the vibration body; one end of the fixing part, which is far away from the vibration main body, is abutted against the supporting part, one side of the fixing part, which is far away from the back plate, is attached to the substrate, and the extending part is arranged right opposite to the sound cavity; the fixed electrode and the effective vibration region have the same shape.

Preferably, the fixed electrode and the effective vibration region have the same size.

Preferably, the fixed arms include four and are arranged at intervals.

Preferably, the vibration main body is rectangular, and the four fixing arms are respectively extended from four corners of the vibration main body.

Preferably, the ineffective vibration parts include four and are respectively disposed in parallel with four sides of the vibration main body.

Preferably, the back plate is fixedly supported on the substrate through the support part.

Compared with the prior art, the MEMS microphone has the advantages that the vibrating membrane is arranged to be the effective vibrating part and the ineffective vibrating part, the effective vibrating part and the part, which is opposite to the sound cavity of the substrate, of the effective vibrating part form the effective vibrating area, the fixed electrode is arranged to be the same as the effective vibrating area of the vibrating membrane in shape, the effective utilization area of the effective vibrating area of the vibrating membrane is increased due to the structure, the effective capacitance of the MEMS microphone is improved, the generation of ineffective parasitic capacitance is limited to the maximum extent, and the acoustic performance of the MEMS microphone is effectively improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:

FIG. 1 is a schematic perspective view of an MEMS microphone according to the present invention;

FIG. 2 is an exploded perspective view of a MEMS microphone of the present invention;

FIG. 3 is a sectional view taken along line A-A of FIG. 1;

FIG. 4 is a schematic structural diagram of a fixed electrode of the MEMS microphone of the present invention;

fig. 5 is a schematic structural diagram of a diaphragm of the MEMS microphone of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the present invention provides an MEMS microphone 100, which includes a substrate 1, a back plate 2, a diaphragm 3 and a support portion 4.

The substrate 1 is provided with an acoustic cavity 11 penetrating through the substrate, and the substrate 1 is made of silicon-based materials and is processed and molded by an MEMS (micro-electromechanical systems) process.

The back plate 2 is fixed on the substrate 1. Specifically, the back plate 2 includes a back plate 21 and a fixed electrode 22.

The back plate 21 is provided with a sound pressure hole 211 penetrating through it.

Referring to fig. 4, the fixed electrode 22 is attached and fixed to one side of the back plate 21 close to the vibrating membrane 3. The fixed electrode 22 is provided with a through hole 221 penetrating through the fixed electrode, and the through hole 221 is communicated with the sound pressure hole 211 in a matching manner and used for balancing sound pressure. The fixed electrode 22 is made of a conductive material.

Referring to fig. 5, the diaphragm 3 is fixed to the substrate 1 and is spaced from the back plate 2 to form a capacitor structure.

The diaphragm 3 is also made of a conductive material so as to form two poles of a capacitive structure with the fixed electrode 22, respectively. The vibrating membrane 3 is driven to vibrate by sound pressure, so that the relative distance between the vibrating membrane 3 and the fixed electrode 22 is changed, the capacitance of a capacitance structure formed by the vibrating membrane 3 and the fixed electrode 22 is changed, and the capacitance is converted into different electric signals to realize sound-electricity conversion.

In the present embodiment, specifically, the diaphragm 3 includes an effective vibration portion 31 and an ineffective vibration portion 32.

The effective vibration portion 31 includes a vibration main body 311 disposed opposite to the acoustic chamber 11, and a fixing arm 312 extended from the vibration main body 311 and fixed to the base 1.

In this embodiment, the fixed arms 312 include four fixed arms and are spaced apart from each other. Preferably, the vibrating main body 311 is rectangular, and four fixing arms 312 are respectively extended from four corners of the vibrating main body 311. Of course, the shape of the vibration body 311 is not limited thereto.

The vibrating body 311 and the portion of the fixed arm 312 facing the acoustic chamber 11 together form an effective vibrating area (not numbered).

The ineffective vibration part 32 is located between two adjacent fixing arms 312 and spaced apart from the effective vibration part 31, and the ineffective vibration part 32 is at least partially fixed to the substrate 1.

Specifically, the ineffective vibration part 32 includes four parts and is respectively disposed in parallel with four sides of the vibration main body 311.

In the present embodiment, the fixed electrode 22 has the same shape as the effective vibration region. The structure increases the effective utilization area of the effective vibration region of the vibration membrane 3, thereby improving the effective capacitance of the MEMS microphone 100, limiting the generation of invalid parasitic capacitance to the maximum extent, and effectively improving the acoustic performance of the MEMS microphone 100. Preferably, the fixed electrode and the effective vibration area have the same size, that is, the orthographic projection of the fixed electrode in the effective vibration area completely coincides with the effective vibration area.

The support portion 4 is fixed to the substrate 1, and in the present embodiment, the back plate 2 is fixed to the substrate 1 through the support portion 1. Preferably, the support portion 4 is of an annular structure and is disposed around the diaphragm 3.

The arrangement of the supporting part 4 increases the effective spacing distance between the back plate 2 and the vibrating membrane 3, and avoids the influence on the acoustic performance caused by insufficient vibration amplitude of the vibrating membrane 3.

Referring to fig. 3 and 5, it can be seen that the ineffective vibrating portion includes a fixing portion 32a fixed to the substrate 1 and an extending portion 32b extending from the fixing portion to the vibrating body. One end of the fixing portion 32a departing from the vibration main body 311 is abutted to the supporting portion 4, one side of the fixing portion 32a departing from the back plate 21 is attached to the substrate 1, and the extending portion 32b is arranged right opposite to the sound cavity 11.

While the foregoing is directed to embodiments of the present invention, it will be understood by those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.

Claims

1. An MEMS microphone comprises a substrate with a sound cavity, a back plate fixed on the substrate and a vibrating membrane fixed on the substrate and arranged opposite to the back plate at intervals to form a capacitor structure, wherein the back plate comprises a back plate and a fixed electrode which is attached to the back plate and is fixed on one side of the back plate close to the vibrating membrane, the vibrating membrane comprises an effective vibrating part and an ineffective vibrating part, the effective vibrating part comprises a vibrating main body which is just opposite to the sound cavity and fixed arms which extend from the vibrating main body and are fixed on the substrate, the fixed arms comprise four fixing arms which are arranged at intervals, the vibrating main body is rectangular, and the four fixing arms extend from the positions of four corners of the vibrating main body respectively; the vibration main body and the part of the fixed arm, which is opposite to the sound cavity, jointly form an effective vibration area; the ineffective vibration part is positioned between two adjacent fixed arms and is arranged at an interval with the effective vibration part, and at least part of the ineffective vibration part is fixed on the substrate; the MEMS microphone also comprises a supporting part fixed on the substrate, and the supporting part is of an annular structure and is arranged around the vibrating membrane; the ineffective vibration part comprises a fixed part fixed on the substrate and an extension part extending from the fixed part to the vibration body; one end of the fixing part, which is far away from the vibration main body, is abutted against the supporting part, one side of the fixing part, which is far away from the back plate, is attached to the substrate, and the extending part is arranged right opposite to the sound cavity; the fixed electrode and the effective vibration area are the same in shape and size.

2. The MEMS microphone according to claim 1, wherein the ineffective vibrating portions include four and are respectively disposed in parallel with four sides of the vibrating body.

3. The MEMS microphone of claim 1, wherein the back plate is fixedly supported to the substrate by the support.