CN111787474A

CN111787474A - MEMS acoustic sensor

Info

Publication number: CN111787474A
Application number: CN202010664854.5A
Authority: CN
Inventors: 赵转转; 柏杨
Original assignee: Ruisheng Technology Nanjing Co Ltd
Current assignee: AAC Technologies Holdings Nanjing Co Ltd; Ruisheng Technology Nanjing Co Ltd
Priority date: 2020-07-10
Filing date: 2020-07-10
Publication date: 2020-10-16
Also published as: WO2022007100A1

Abstract

The invention provides an MEMS (micro-electromechanical system) acoustic sensor which comprises a substrate with a back cavity and a capacitor system fixed on the substrate, wherein the capacitor system comprises a vibrating diaphragm and a back plate which is opposite to the vibrating diaphragm and arranged at an interval, an insulating gap is formed between the vibrating diaphragm and the back plate, the back plate comprises an electrode layer and a first insulating layer arranged on one side of the electrode layer, which faces the vibrating diaphragm, a through hole penetrates through the back plate, the through hole comprises a first through hole penetrating through the electrode layer and a second through hole penetrating through the first insulating layer, and the aperture of one side, close to the vibrating diaphragm, of the second through hole is larger than that of the first through hole. Compared with the related art, the MEMS acoustic sensor provided by the invention is designed into a structure for reducing the damping of the diaphragm so as to improve the signal-to-noise ratio.

Description

MEMS acoustic sensor

[ technical field ] A method for producing a semiconductor device

The invention relates to the field of acoustoelectrics, in particular to an MEMS (micro-electromechanical system) acoustic sensor.

[ background of the invention ]

With the development of wireless communication, more and more mobile phone users are around the world, and the requirements of the users on the mobile phones are met for calling and providing a high-quality calling effect, especially, the calling quality of the mobile phones is more important due to the development of the current mobile multimedia technology, and the microphone of the mobile phones is used as a voice pickup device of the mobile phones, and the design of the microphone directly affects the calling quality, and the MEMS acoustic sensor as an important component of the microphone is more important.

MEMS acoustic sensor among the correlation technique is including the basement that has the back cavity and be fixed in the electric capacity system of basement, electric capacity system includes vibrating diaphragm and the relative back plate that sets up with the vibrating diaphragm at an interval, form insulating clearance between vibrating diaphragm and the back plate, when the acoustic pressure acted on the vibrating diaphragm, there was pressure difference vibrating diaphragm orientation back plate and the relative both sides that deviate from the back plate for the vibrating diaphragm is close to the motion of back plate or keep away from the back plate, thereby arouses the change of electric capacity between vibrating diaphragm and the back plate, realizes the conversion of sound signal to the signal of telecommunication. However, since the signal-to-noise ratio of the MEMS acoustic sensor is affected by the damping of the diaphragm, the diaphragm of the MEMS acoustic sensor in the related art is too damped, resulting in an undesirable signal-to-noise ratio of the MEMS acoustic sensor.

[ summary of the invention ]

It is an object of the present invention to provide a MEMS acoustic sensor that improves the signal-to-noise ratio by designing a structure that reduces the damping of the diaphragm.

In order to achieve the above object, the present invention provides an MEMS acoustic sensor, which includes a substrate having a back cavity, and a capacitor system fixed on the substrate, where the capacitor system includes a diaphragm and a back plate opposite to the diaphragm and spaced apart from the diaphragm, an insulation gap is formed between the diaphragm and the back plate, the back plate includes an electrode layer and a first insulation layer disposed on one side of the electrode layer facing the diaphragm, a through hole is formed in the back plate in a penetrating manner, the through hole includes a first through hole penetrating through the electrode layer and a second through hole penetrating through the first insulation layer, and a hole diameter of the second through hole on a side close to the diaphragm is larger than a hole diameter of the first through hole.

Preferably, the aperture of the second through hole is gradually reduced in a direction from the first insulating layer to the electrode layer.

Preferably, on a cross section perpendicular to the back plate, an inner wall of the second through hole is an arc surface, and a curvature center of the inner wall of the second through hole is located on a side of the inner wall of the second through hole facing the diaphragm.

Preferably, the back plate further comprises a second insulating layer arranged on one side, away from the diaphragm, of the electrode layer, and the through hole further comprises a third through hole penetrating through the second insulating layer.

Preferably, the aperture of the third through hole is smaller than the aperture of the first through hole.

Preferably, the aperture of the third via hole is gradually reduced in a direction from the electrode layer to the second insulating layer.

Preferably, on a cross section perpendicular to the back plate, the inner wall of the third through hole is an arc surface, and the center of curvature of the inner wall of the third through hole is located on one side of the inner wall of the third through hole, which is deviated from the axis of the third through hole.

Preferably, the aperture of the third through hole on the side away from the electrode layer is larger than the aperture of the first through hole.

Preferably, the aperture of the third through hole gradually increases in a direction from the electrode layer to the first insulating layer.

Preferably, on a cross section perpendicular to the back plate, an inner wall of the third through hole is an arc surface, and a curvature center of the inner wall of the third through hole is located on a side of the inner wall of the third through hole, which is away from the diaphragm.

Preferably, the first through hole and the second through hole have the same hole diameter, and the first through hole and the third through hole have the same hole diameter.

Compared with the prior art, the MEMS acoustic sensor has the advantages that the aperture of the second through hole close to one side of the vibrating diaphragm is larger than that of the first through hole so as to reduce the area of the first insulating layer opposite to the vibrating diaphragm, and the area of the first insulating layer opposite to the vibrating diaphragm is reduced so as to reduce the constraint effect of the first insulating layer on the air flow, so that the viscous force of air flowing through the first insulating layer can be reduced, and the damping force of the vibrating diaphragm can be further reduced. This ensures that the signal-to-noise ratio of the MEMS acoustic sensor is increased without reducing the sensitivity of the MEMS acoustic sensor.

[ 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 schematic structural diagram of a first embodiment of a MEMS acoustic sensor according to the present invention;

FIG. 2 is a schematic structural diagram of a second embodiment of the MEMS acoustic sensor of the present invention;

FIG. 3 is a schematic structural diagram of a third embodiment of the MEMS acoustic sensor of the present invention;

FIG. 4 is a schematic structural diagram of a fourth embodiment of the MEMS acoustic sensor of the present invention;

FIG. 5 is a schematic structural diagram of a fifth embodiment of a MEMS acoustic sensor in accordance with the present invention;

FIG. 6 is a schematic structural diagram of a sixth embodiment of a MEMS acoustic sensor in accordance with the present invention;

fig. 7 is a schematic structural diagram of a seventh MEMS acoustic sensor embodiment of the present invention.

[ 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.

Example one

Referring to fig. 1, the MEMS acoustic sensor includes a substrate 1 having a back cavity 1A and a capacitor system 3 fixed to the substrate 1, where the capacitor system 3 includes a diaphragm 5 and a back plate 7 opposite to the diaphragm 5 and spaced apart from the diaphragm 5, and an insulation gap 9 is formed between the diaphragm 5 and the back plate 7.

When pressure (sound waves) acts on the diaphragm 5. The diaphragm 5 vibrates in a direction approaching and separating from the back plate so that the capacitance of the capacitor between the diaphragm 5 and the back plate 7 changes. Therefore, an electric signal corresponding to the change in pressure (acoustic wave) can be generated, which is output through an external circuit connected to the capacitance system 3.

As shown in fig. 1, the diaphragm 5 and the back plate 7 are fixed to the substrate 1 through an insulating member 10. The back plate 7 comprises an electrode layer 71 and is arranged on the electrode layer 71 facing the first insulating layer 73 on one side of the diaphragm 5, a through hole 7A is formed in the back plate 7 in a penetrating mode, the through hole 7A comprises a first through hole 71A penetrating through the electrode layer 71 and a second through hole 73A penetrating through the first insulating layer 73, the second through hole 73A is close to the aperture on one side of the diaphragm 5 and is larger than the aperture of the first through hole 71A, and therefore the size of the first insulating layer 73 and the area of the diaphragm 5 facing one side are reduced. Because the vibrating diaphragm during vibration, arouse the air flow between vibrating diaphragm and the first insulating layer, and the air flow receives the restrictive action of vibrating diaphragm and first insulating layer, because the viscosity when the air flow, the air flow can produce viscous force, and then leads to the increase of vibrating diaphragm damping force, and through reducing first insulating layer with the vibrating diaphragm just to one side's area, can reduce the restrictive action of first insulating layer to the air flow to can reduce the air and flow through the viscous force when first insulating layer, and then can reduce the damping force of vibrating diaphragm.

In the present embodiment, the diameters of the first through hole 71A and the second through hole 73A adjacent to each other are equal.

In the present embodiment, the aperture diameters of the first through hole 71A and the second through hole 73A are gradually decreased in the direction from the first insulating layer 73 to the electrode layer 71. As shown in fig. 1, in a cross section perpendicular to the back plate 7, inner walls of the first through hole 71A and the second through hole 73A are both flat.

Example two

Referring to fig. 2, the difference between the second embodiment and the first embodiment is: on the cross section perpendicular to the back plate 7, the inner wall of the first through hole 71A and the inner wall of the second through hole 73A are both arc surfaces, the curvature center of the inner wall of the first through hole 71A is located on one side of the inner wall of the first through hole 71A facing the diaphragm 5, and the curvature center of the inner wall of the second through hole 73A is located on one side of the inner wall of the second through hole 73A facing the diaphragm 5.

EXAMPLE III

Referring to fig. 3, the difference between the third embodiment and the first embodiment is: the back plate 7 further comprises a second insulating layer 75 arranged on one side, away from the diaphragm 5, of the electrode layer 71, the through hole 7A further comprises a third through hole 75A penetrating through the second insulating layer 75, and the aperture of the third through hole 75A is smaller than that of the first through hole 71A.

In this embodiment, the diameters of the third through hole 75A and the first through hole 71A adjacent to each other are equal.

In this embodiment, the aperture of the third through hole 75A gradually decreases in the direction from the electrode layer 71 to the second insulating layer 75. As shown in fig. 3, in a cross section perpendicular to the back plate 7, the inner wall of the third through hole 75A is a plane.

Example four

Referring to fig. 4, the difference between the fourth embodiment and the second embodiment is: the back plate 7 further comprises a second insulating layer 75 arranged on one side, away from the diaphragm 5, of the electrode layer 71, the through hole 7A further comprises a third through hole 75A penetrating through the second insulating layer 75, and the aperture of the third through hole 75A is smaller than that of the first through hole 71A.

As shown in fig. 4, in a cross section perpendicular to the back plate 7, an inner wall of the third through hole 75A is an arc surface, and a curvature center of the inner wall of the third through hole 75A is located on a side thereof facing away from an axis of the third through hole 75A.

EXAMPLE five

Referring to fig. 5, the difference between the fifth embodiment and the first embodiment is: on a cross section perpendicular to the back plate 7, an inner wall of the first through hole 71A is a plane and perpendicular to the diaphragm 5.

The back plate 7 further comprises a second insulating layer 75 arranged on one side, away from the diaphragm 5, of the electrode layer 71, the through hole 7A further comprises a third through hole 75A penetrating through the second insulating layer 75, and the aperture of the third through hole 75A is larger than that of the first through hole 71A.

In this embodiment, the aperture of the third through hole 75A gradually increases along the direction from the electrode layer 71 to the second insulating layer 75. As shown in fig. 5, in a cross section perpendicular to the back plate 7, the inner wall of the third through hole 75A is a plane.

EXAMPLE six

Referring to fig. 6, the difference between the sixth embodiment and the fifth embodiment is: on a cross section perpendicular to the back plate 7, an inner wall of the second through hole 73A is an arc, and a curvature center of the inner wall of the second through hole 73A is located on a side thereof facing the diaphragm 5.

EXAMPLE seven

Referring to fig. 7, the seventh embodiment differs from the sixth embodiment in that: on the cross section perpendicular to the back plate 7, the inner wall of the first through hole 71A is an arc surface, and the curvature center of the inner wall of the first through hole 71A is located on the side of the inner wall departing from the diaphragm 5.

In the above embodiments, in the third and fourth embodiments, since the aperture of the first through hole 71A is larger than the aperture of the third through hole 75A, the problem of short circuit of the MEMS acoustic sensor caused by large dust particles entering the MEMS acoustic sensor can be avoided under the condition that the sensitivity of the MEMS acoustic sensor is not changed (that is, under the condition that the effective area of the electrode layer 71 is not changed, which is equivalent to increasing the effective area of the second insulating layer); in the fifth to seventh embodiments, since the apertures of the first through hole 71A are smaller than the apertures of the second through hole 73A and the third through hole 75A, the impedance of the through hole 7A can be reduced, and the effective area of the electrode layer 71 can be increased, so that the sensitivity of the MEMS acoustic sensor can be improved, and the problem of short circuit of the MEMS acoustic sensor caused by large dust particles entering the MEMS acoustic sensor can be avoided

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. The utility model provides a MEMS acoustic sensor, is including the basement that has the back of the body chamber and be fixed in the capacitance system of basement, capacitance system include the vibrating diaphragm and with the relative back plate that just the interval set up of vibrating diaphragm, the vibrating diaphragm with form insulating gap between the back plate, its characterized in that, the back plate includes the electrode layer and locates the electrode layer orientation the first insulation layer of vibrating diaphragm one side, it is equipped with the through-hole to run through on the back plate, the through-hole is including running through the first through-hole of electrode layer and running through the second through-hole on first insulation layer, the second through-hole is close to the aperture of vibrating diaphragm one side is greater than the aperture of first through-hole.

2. The MEMS acoustic sensor of claim 1, wherein the aperture of the second via is gradually reduced in a direction from the first insulating layer to the electrode layer.

3. The MEMS acoustic sensor of claim 2, wherein, in a cross section perpendicular to the back plate, the inner wall of the second through hole is a curved surface, and the center of curvature of the inner wall of the second through hole is located on a side thereof facing the diaphragm.

4. The MEMS acoustic sensor of any one of claims 1-3, wherein the back plate further comprises a second insulating layer disposed on a side of the electrode layer facing away from the diaphragm, and the through-hole further comprises a third through-hole extending through the second insulating layer.

5. The MEMS acoustic sensor of claim 4, wherein the third via has a smaller aperture than the first via.

6. The MEMS acoustic sensor of claim 5, wherein the aperture of the third via is gradually reduced in a direction from the electrode layer to the second insulating layer.

7. The MEMS acoustic sensor of claim 5, wherein, in a cross-section perpendicular to the backplate, the inner wall of the third via is a curved surface, and the center of curvature of the inner wall of the third via is on a side thereof facing away from the axis of the third via.

8. The MEMS acoustic sensor of claim 4, wherein a side of the third via facing away from the electrode layer has a larger aperture than a first via.

9. The MEMS acoustic sensor of claim 8, wherein the aperture of the third via hole gradually increases in a direction from the electrode layer to the first insulating layer.

10. The MEMS acoustic sensor of claim 9, wherein, in a cross section perpendicular to the back plate, an inner wall of the third through hole is a curved surface, and a center of curvature of the inner wall of the third through hole is located on a side of the inner wall thereof facing away from the diaphragm.

11. The MEMS acoustic sensor of claim 4, wherein the first via is the same aperture adjacent to the second via and the first via is the same aperture adjacent to the third via.