CN215935098U

CN215935098U - Double-back-plate MEMS microphone

Info

Publication number: CN215935098U
Application number: CN202122197950.6U
Authority: CN
Inventors: 童贝; 石正雨; 张睿
Original assignee: AAC Acoustic Technologies Shenzhen Co Ltd
Current assignee: AAC Technologies Holdings Shenzhen Co Ltd
Priority date: 2021-09-10
Filing date: 2021-09-10
Publication date: 2022-03-01
Anticipated expiration: 2031-09-10

Abstract

The utility model provides a double-backboard MEMS microphone which comprises a substrate with a cavity, a first backboard, a vibrating diaphragm and a second backboard, wherein the first backboard is arranged on the substrate and integrally formed with the substrate through etching, the vibrating diaphragm is opposite to the first backboard and arranged at intervals, and the second backboard is opposite to the vibrating diaphragm and arranged at intervals. The first back plate is directly formed on the substrate by etching, so that the back plate thickness is thicker than that of the prior art, and the reliability in falling is enhanced.

Description

Double-back-plate MEMS microphone

[ technical field ] A method for producing a semiconductor device

The utility model relates to the field of sensors, in particular to a double-back-plate MEMS microphone.

[ background of the utility model ]

The MEMS microphone is an electric energy sound changer manufactured by a micro-machining technology and has the characteristics of small volume, good frequency response characteristic, low noise and the like. With the development of miniaturization and thinning of electronic devices, MEMS microphones are increasingly widely used for these devices.

The MEMS microphone in the related art includes a silicon substrate and a plate capacitor composed of a diaphragm and a back plate, the diaphragm is opposite to and spaced apart from the back plate. The vibrating diaphragm vibrates under the action of sound waves, so that the distance between the vibrating diaphragm and the back plate is changed, the capacitance of the plate capacitor is changed, and sound wave signals are converted into electric signals. As an improvement, in the related art, a double-layer back plate is arranged on a silicon substrate, and a diaphragm is arranged between the double-layer back plates to output a differential signal, so as to improve the sensitivity of the microphone, however, in the structure, the back plate close to the silicon substrate is formed by etching silicon nitride or polymer on the silicon substrate, and the thickness of the back plate can only be limited, generally 3 microns to 5 microns, and at most 10 microns, so that there is a certain risk in terms of drop reliability, and the structure implementation of a general double-layer back plate still has certain complexity in the process.

Therefore, there is a need to provide a new MEMS microphone to solve the above technical problems.

[ Utility model ] content

The utility model aims to provide a double-backboard MEMS microphone with high reliability and high sensitivity.

In order to achieve the above object, the present invention provides a dual-backplate MEMS microphone, which includes a substrate having a cavity, a first backplate disposed on the substrate and formed by etching integrally with the substrate, a diaphragm disposed opposite to the first backplate at an interval, and a second backplate disposed opposite to the diaphragm at an interval.

Preferably, the double-backplate MEMS microphone comprises a first insulating layer disposed on the first backplate, the diaphragm comprises a fixed end located at an intermediate position, and the fixed end is fixedly connected with the first backplate through the first insulating layer.

Preferably, the diaphragm includes a free end located at the periphery, the dual-backplate MEMS microphone further includes a second insulating layer disposed on the substrate and a spacer disposed on the second insulating layer, the free end of the diaphragm is connected to the spacer through a spring structure, and the spacer is fixedly connected to the substrate through the second insulating layer.

Preferably, the first back plate includes a fixing portion located at an intermediate portion and disposed corresponding to a fixed end of the diaphragm, and the first insulating layer is disposed on the fixing portion.

Preferably, the first back plate further comprises a connecting portion for connecting the fixing portion and the substrate, the connecting portion comprises a plurality of radial beams, and a first through hole is formed between every two adjacent beams.

Preferably, the connecting portion comprises at least one annular connecting arm connecting the respective beams.

Preferably, the thickness of the first back plate is 50 to 100 micrometers.

Preferably, the second backboard is provided with a second through hole.

Preferably, the substrate and the first back plate are a silicon material substrate and a first back plate.

Compared with the prior art, the first back plate of the double-back-plate MEMS microphone is directly formed on the substrate by etching, so that the thicker back plate thickness can be achieved, and the reliability in falling is enhanced.

[ description of the 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 perspective view of a dual-backplate MEMS microphone of the present invention;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a perspective view of a substrate and a first backplate in a dual-backplate MEMS microphone according to the present invention;

FIG. 4 is a perspective view of the substrate and the first backplate of FIG. 3 from another angle;

FIG. 5 is a perspective view of a substrate and a first backplate in a dual-backplate MEMS microphone according to another embodiment of the present invention;

FIG. 6 is a perspective view of the substrate and the first backplate of FIG. 5 from another angle.

[ detailed description ] embodiments

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. 1-2, a dual-backplate MEMS microphone 100 is provided, where the dual-backplate MEMS microphone 100 includes a substrate 1 having a cavity 10, a first backplate 2 disposed on the substrate 1 and formed by etching integrally with the substrate 1, a diaphragm 3 disposed opposite to the first backplate 2 at an interval, a second backplate 4 disposed opposite to the diaphragm 3 at an interval, a first insulating layer 5 disposed on the first backplate 2, a second insulating layer 6 disposed on the substrate 1, and a spacer 7 disposed on the second insulating layer 6.

The first backboard 2 is arranged on one side of the vibrating diaphragm 3 close to the substrate 1, and the second backboard 4 is arranged on the other side of the vibrating diaphragm 3 far away from the substrate 1.

As shown in fig. 3 and 4, the first backplate 2 covers the cavity 10, the first backplate 2 and the substrate 1 are integrated, that is, the first backplate 2 is directly etched on the substrate material during the manufacturing process, the substrate 1 is made of silicon material, and therefore the first backplate 2 is also made of silicon material. The first back plate 2 comprises a fixing portion 21 located in the middle and a connecting portion 22 connecting the fixing portion 21 and the substrate 1, the first insulating layer 5 is arranged on the fixing portion 21, the connecting portion 22 comprises a plurality of radial beams 221, and a first through hole 23 is formed between every two adjacent beams 221. The beam 221 is a strip structure, and the first back plate 2 is circular. The thickness of the first back plate is 50-100 micrometers, in the prior art, the thickness of the first back plate is 3-5 micrometers, and at most 10 micrometers can be achieved approximately, and due to the scheme of the utility model, the first back plate is formed by directly etching the substrate material, so that the thickness of the first back plate can be at least 50 micrometers, stability in the falling process is achieved, and damage in the falling process is greatly reduced.

In another embodiment of the present invention, as shown in fig. 5 and 6, the first backplate 2' further comprises at least one annular connecting arm 24 connecting the beams, and in this embodiment, two connecting arms 24 are shown. Of course, in other embodiments, the beams of the first backplate may also be curved and wavy, and the first backplate may also be of other shapes, for example, regular hexagon.

The diaphragm 3 is made of a polymer material, the diaphragm 3 includes a fixed end 31 located in the middle and a free end 32 located at the periphery, the fixed end 31 is disposed opposite to the fixed portion 21 of the first backplate, and the fixed end 31 is fixedly connected with the fixed portion 21 through the first insulating layer 5, so that the diaphragm 3 and the first backplate 2 are fixed relatively. The free end 32 of the diaphragm 3 is connected with the gasket 7 through a spring structure 8, the gasket 7 is fixedly connected with the substrate 1 through the second insulating layer 6, so that the diaphragm 3 is fixed, and the gasket 7 is in an annular structure surrounding the diaphragm 3.

The second backplate 4 is made of silicon nitride material, the second backplate 4 includes a main body portion 41 horizontally disposed and a bending portion 42 bent and extended from the main body portion 41, the bending portion 42 is fixed to the substrate 1, and the second backplate 4 is provided with a second through hole 43.

And a supporting insulating layer is not reserved between the vibrating diaphragm and the first back plate and between the vibrating diaphragm and the second back plate, and the vibrating diaphragm is integrally fixed through the middle first insulating layer and the peripheral spring structure. Spring structure's fixed for during the effect of the same external acoustic pressure, the vibrating diaphragm can produce bigger displacement volume, improves two backplate MEMS microphone sensitivity, simultaneously, makes when the vibrating diaphragm has the internal stress, and the vibrating diaphragm can release stress through deformation, thereby reduces the influence of stress to vibrating diaphragm rigidity, thereby further improves two backplate MEMS microphone sensitivity.

Because the structure is a double-backboard structure, the variable quantity of the capacitor can be subjected to differential operation, and the sensitivity can be further improved. The substrate and the first back plate in the structure are directly made of silicon materials, the stability and rigidity requirements of the structure are fully guaranteed, a certain buffering effect is achieved on the deformation of the vibrating diaphragm, and the reliability of the microphone in the processes of falling and the like can be obviously improved.

The first back plate is formed by directly etching the substrate material, so that the manufacturing process of the scheme is simplified, and meanwhile, the thickness of the first back plate can be thicker, the further stability in the falling process is realized, and the damage in the falling process is greatly reduced.

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 utility model.

Claims

1. The double-backplate MEMS microphone is characterized by comprising a substrate with a cavity, a first backplate, a vibrating diaphragm and a second backplate, wherein the first backplate is arranged on the substrate and integrally formed with the substrate through etching, the vibrating diaphragm is opposite to the first backplate and arranged at intervals, and the second backplate is opposite to the vibrating diaphragm and arranged at intervals.

2. The dual-backplate MEMS microphone of claim 1, comprising a first insulating layer disposed on the first backplate, the diaphragm comprising a fixed end at an intermediate position, the fixed end being fixedly connected to the first backplate through the first insulating layer.

3. The dual-backplate MEMS microphone of claim 2, wherein the diaphragm comprises a free end at a periphery, the dual-backplate MEMS microphone further comprising a second insulating layer disposed on the substrate and a spacer disposed on the second insulating layer, the free end of the diaphragm is connected to the spacer through a spring structure, and the spacer is fixedly connected to the substrate through the second insulating layer.

4. The dual-backplate MEMS microphone of claim 2, wherein the first backplate comprises a fixed portion disposed at a middle portion corresponding to the fixed end of the diaphragm, and the first insulating layer is disposed at the fixed portion.

5. The dual-backplate MEMS microphone of claim 4, wherein the first backplate further comprises a connecting portion connecting the fixing portion and the substrate, the connecting portion comprising a plurality of radial beams, a first via hole being formed between adjacent beams.

6. The dual-backplate MEMS microphone of claim 5, wherein the connecting portion comprises at least one annular connecting arm connecting the respective beams.

7. The dual-backplate MEMS microphone of claim 1, wherein the first backplate has a thickness of 50 to 100 microns.

8. The dual-backplate MEMS microphone of claim 1, wherein the second backplate has a second through hole formed therein.

9. The dual-backplate MEMS microphone of claim 1, wherein the substrate and first backplate are a substrate of silicon material and first backplate.