CN111918189A

CN111918189A - MEMS loudspeaker

Info

Publication number: CN111918189A
Application number: CN202010665048.XA
Authority: CN
Inventors: 但强; 程诗阳; 朱国; 李杨
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: 2020-11-10
Also published as: WO2022007054A1

Abstract

The invention provides an MEMS loudspeaker which comprises a base, a vibrating diaphragm positioned above the base and a driving electrode part arranged between the base and the vibrating diaphragm, wherein a driving electrode used for driving the vibrating diaphragm to vibrate along the vertical direction is formed on the driving electrode part, and the driving electrode part comprises at least three conducting layers and two insulating layers. The driving electrode part with the multilayer structure is arranged, so that a non-contact type driving diaphragm is realized, compared with the traditional contact type driving diaphragm, the rigidity of the diaphragm and the size of the electrostatic driving force can be independently adjusted, the set sound pressure requirement of the MEMS loudspeaker is ensured, and compared with the traditional contact type driving diaphragm, the rigidity of the diaphragm and the size of the electrostatic driving force can be independently adjusted, and the set sound pressure requirement of the MEMS loudspeaker is ensured; in addition, the invention can reduce harmonic distortion through the electrodes excited differentially.

Description

MEMS loudspeaker

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of sound production devices, in particular to an MEMS (micro-electromechanical system) loudspeaker.

[ background of the invention ]

In the prior art, the MEMS loudspeaker scheme is that a top layer silicon is etched into a slender beam structure, and the slender beam structure vibrates in a certain driving mode to make sound. However, the low-frequency sound pressure of the sound production mode is far inferior to that of the out-of-plane vibration scheme.

Therefore, it is necessary to provide a MEMS speaker having a new structure to solve the above problems.

[ summary of the invention ]

The invention aims to provide a MEMS loudspeaker with a vibrating diaphragm driven to vibrate by static electricity.

The technical scheme of the invention is as follows: the MEMS loudspeaker comprises a base, a vibrating diaphragm positioned above the base and a driving electrode part arranged between the base and the vibrating diaphragm, wherein a driving electrode used for driving the vibrating diaphragm to vibrate along the vertical direction is formed on the driving electrode part;

the driving electrode part comprises at least three conductive layers and two insulating layers, the conductive layers and the insulating layers are alternately stacked to enable one insulating layer to be sandwiched between every two conductive layers, the driving electrode part is provided with a separation groove penetrating through all the conductive layers and all the insulating layers to separate the driving electrode part into an movable electrode part and a static electrode part, the movable electrode part and the vibrating diaphragm are relatively fixed, and the static electrode part and the base are relatively fixed;

the driving electrode comprises at least one movable electrode formed on the movable electrode part and at least one static electrode formed on the static electrode part, each movable electrode is formed by electrically connecting at least two conductive layers, each static electrode is formed by electrically connecting at least two conductive layers, at least one conductive layer is used for forming the movable electrode and the static electrode, at least one conductive layer is used for forming the movable electrode but not used for forming the static electrode, and at least one conductive layer is used for forming the static electrode but not used for forming the movable electrode.

Optionally, the driving electrode portion includes at least four conductive layers, one of the moving electrode and the static electrode includes a first electrode and a second electrode arranged along a vertical direction and electrically isolated from each other, and the first electrode and the second electrode are used for connecting a differential signal.

Alternatively, the driving electrode portion includes four conductive layers, the first electrode is formed on the upper two conductive layers, the second electrode is formed on the lower two conductive layers, and the static electrode is formed on the middle two conductive layers.

Optionally, one of the moving electrode and the static electrode includes a first electrode and a second electrode that are arranged in a direction perpendicular to a vibration direction of the diaphragm and are electrically isolated from each other, and the first electrode and the second electrode are used for connecting a differential signal.

Optionally, the other of the moving electrode and the static electrode includes a third electrode and a fourth electrode that are arranged in a direction perpendicular to the vibration direction of the diaphragm and are electrically isolated from each other, the third electrode is opposite to the first electrode in a matching manner, the fourth electrode is opposite to the second electrode in a matching manner, and the third electrode and the fourth electrode are electrically connected.

Optionally, a plurality of cuts are disposed on the conductive portion to separate the first electrode from the second electrode and the third electrode from the fourth electrode.

Optionally, the driving electrode part includes three conductive layers, the first electrode is formed of an upper two-layer conductive layer, the second electrode is formed of a lower two-layer conductive layer, the third electrode is formed of a lower two-layer conductive layer, and the fourth electrode is formed of an upper two-layer conductive layer.

Optionally, the number of the first electrodes and the second electrodes is equal.

Optionally, the separation groove is a toothed groove.

Optionally, the diaphragm includes a vibrating portion located in a central region and a fixing portion located at a periphery of the vibrating portion, the MEMS speaker further includes a connecting portion located between the driving electrode portion and the diaphragm, the connecting portion includes a first connecting portion and a second connecting portion arranged at an interval, the first connecting portion is used for connecting the static electrode portion and the fixing portion, and the second connecting portion is used for connecting the moving electrode portion and the vibrating portion.

Optionally, the vibrating portion includes a dome portion located at the center and a folded ring portion located at the periphery of the dome portion, and the second connecting portion is used for connecting the dome portion and the electrode portion.

Optionally, the static electrode portion includes a fixed end fixed to the base and an electrode end located inside the fixed end and used for forming the static electrode, and the first connection portion is used for connecting the fixed end and the fixed portion.

Optionally, a cavity is opened in the center of the base, a first through hole communicated with the cavity is opened in the center of the driving electrode part, and a second through hole communicated with the first through hole is opened in the center of the connecting part.

The invention has the beneficial effects that: the driving electrode part with multiple layers of conducting layers is arranged, and different layers of conducting layers are respectively selected from the conducting layers in the electrode part and the static electrode part to form the dynamic electrode and the static electrode, so that the existing partial areas between the dynamic electrode and the static electrode are opposite, and parts which are not opposite to each other are arranged, so that electrostatic driving can be formed after the dynamic electrode and the static electrode are electrified, the vibrating diaphragm is driven to realize out-of-plane vibration, the low-frequency sound pressure performance is excellent, and compared with the traditional contact type driving vibrating diaphragm, the rigidity of the vibrating diaphragm and the size of the electrostatic driving force can be independently adjusted, and the set sound pressure requirement of the MEMS loudspeaker is met; in addition, the invention can reduce harmonic distortion through the electrodes excited differentially.

[ description of the drawings ]

FIG. 1 is a perspective view of one embodiment of a MEMS speaker of the present invention;

FIG. 2 is a cross-sectional view taken at I-I of FIG. 1;

FIG. 3 is a cross-sectional view taken at A in FIG. 2;

FIG. 4 is an exploded view of the MEMS speaker of FIG. 1;

FIG. 5 is a simplified structural diagram of the out-of-plane movement of the MEMS speaker of FIG. 1;

FIG. 6 is a schematic diagram of a second embodiment of a MEMS speaker;

FIG. 7 is a cross-sectional view taken at II-II of FIG. 6;

FIG. 8 is a cross-sectional view taken at B of FIG. 7;

FIG. 9 is a simplified structural diagram of the out-of-plane movement of the MEMS speaker of FIG. 6;

FIG. 10 is a sectional view of a third embodiment of a MEMS speaker;

FIG. 11 is a sectional view taken at a location of a section of FIG. 10;

fig. 12 is a sectional view of fig. 10 at another division.

[ detailed description ] embodiments

The invention is further described with reference to the following figures and embodiments.

Referring to fig. 1 to 5, a MEMS speaker according to a first embodiment of the present disclosure includes a base 1, a diaphragm 2 located above the base 1, and a driving electrode portion 3 disposed between the base 1 and the diaphragm 2, where the driving electrode portion 3 is formed with a driving electrode for driving the diaphragm 2 to vibrate in an up-down direction. The driving electrode part 3 comprises at least three conductive layers 32 and two insulating layers 33, the conductive layers 32 and the insulating layers 33 are alternately laminated so that one insulating layer 33 is sandwiched between every two conductive layers 32, the driving electrode part 3 is provided with a separation groove 34 penetrating through all the conductive layers 32 and all the insulating layers 33 so as to separate the driving electrode part 3 into an movable electrode part 35 and a static electrode part 36, the movable electrode part 35 is fixed relative to the diaphragm 2, and the static electrode part 36 is fixed relative to the base 1. Preferably, the separation groove 34 is a toothed groove.

The driving electrode includes at least one moving electrode 351 formed on the moving electrode portion 35 and at least one static electrode 361 formed on the static electrode portion 36, each moving electrode 351 is formed by electrically connecting at least two conductive layers 32, each static electrode 361 is formed by connecting at least two conductive layers 32, at least one conductive layer 32 is used for forming both the moving electrode 351 and the static electrode 361, at least one conductive layer 32 is used for forming the moving electrode 351 but not for forming the static electrode 361, and at least one conductive layer 32 is used for forming the static electrode 361 but not for forming the moving electrode 351. That is, in the direction in which conductive layer 32 and insulating layer 33 are stacked, movable electrode 351 and stationary electrode 361 face each other at least in a partial region, at least a partial region of movable electrode 351 does not face stationary electrode 361, and at least a partial region of stationary electrode 361 does not face movable electrode 351.

Referring to fig. 5, electrostatic electrode 361 and electrostatic electrode 351 have a height H facing each other in the vertical direction (arrow direction) and a length L facing each other in the horizontal direction. When a driving voltage is applied to the static electrode 361 and the moving electrode 351, an electrostatic force is generated between the static electrode 361 and the moving electrode 351, so that the moving electrode part 35 moves in the up-down direction under the action of the electrostatic force, thereby realizing sound emission. In the present embodiment, the driving electrode portion is formed by alternately stacking 3

conductive layers

32 and 2 insulating layers. Preferably, the thickness of the insulating layer 33 is much smaller than that of the conductive layer 32, so that the electrostatic electrode part 36 and the movable electrode 35 have a compact structure and a small volume. Optionally, the thickness of the conductive layer 32 is between 1um and 100um, and the thickness of the insulating layer 33 is between 0.05um and 10um, which can be used in combination according to the requirement in the specific application process.

In the present embodiment, the static electrode 361 is formed by electrically connecting the lower two conductive layers 32 of the 3 conductive layers 32, and the dynamic electrode 352 is formed by electrically connecting the upper two conductive layers 32 of the 3 conductive layers 32.

In the present embodiment, the diaphragm 2 is a flexible thin-plate structure, and includes a vibrating portion 21 located in a central region and a fixing portion 22 located at a periphery of the vibrating portion, where the vibrating portion 21 includes a dome portion 211 located in the center, a corrugated portion 212 located at the periphery of the dome portion 211, and an auxiliary portion 213 located at the periphery of the corrugated portion. Specifically, the cross section of the corrugated portion 212 may be one or a combination of a rectangle, a triangle, and a circle. It can be known of course that, the shape of the bending ring part 212 can be adjusted according to the use requirement in the specific application process, as long as the bending rigidity of the vibrating diaphragm 2 can be reduced, and the purpose of increasing the amplitude can be achieved. The thicknesses of the auxiliary portion 213 and the ball top portion 211 may not be uniform. Alternatively, the thickness of the dome 211 is greater than the thickness of the auxiliary part 213, so that the center of gravity of the diaphragm 2 is located in the middle of the diaphragm 2, thereby ensuring piston movement of the dome 211 on the diaphragm 2 when the diaphragm 2 is driven to move by the moving electrode part 35.

In the present embodiment, the MEMS speaker further includes a connection portion 4 connecting the diaphragm 2 and the driving electrode portion 3, and the connection portion 4 specifically includes a first connection portion 41 connecting the static electrode portion 36 and the fixing portion 22, and a second connection portion 42 connecting the movable electrode portion 35 and the dome portion 211. Specifically, the static electrode part 36 includes a fixed end fixed to the susceptor 1 and an electrode end located inside the fixed end and forming the static electrode, and the first connection part 41 is configured to connect the fixed end and the fixed part 22.

In the present embodiment, a cavity 11 is opened in the center of the base 1, a first through hole 37 communicating with the cavity is opened in the center of the driving electrode portion 3, and a second through hole 43 communicating with the first through hole 37 is opened in the center of the connecting portion 4.

The overall shape of the electrostatic driving structure in the MEMS speaker in this embodiment is a circular structure, and certainly, the electrostatic driving structure can also be configured as a rectangular or triangular structure, and can be adjusted according to the use requirements in different use scenes.

In other embodiments, the driving electrode portion 3 includes at least four conductive layers 32, and one of the moving electrode 351 and the static electrode 361 includes a first electrode and a second electrode that are arranged in the vertical direction and are electrically isolated from each other, and the first electrode and the second electrode are used for connecting a differential signal. The driving electrode portion includes four conductive layers 32, a first electrode formed on the upper two conductive layers 32, a second electrode formed on the lower two conductive layers 32, and a static electrode 361 formed on the middle two conductive layers 32.

Referring to fig. 6 to 9, the second embodiment of the MEMS speaker is different from the first embodiment in that the structures of the static electrode part 36 and the moving electrode part 35, in this embodiment, the driving electrode part 3 has a 7-layer structure, wherein 4 layers are the

conductive layers

32, 3 layers are the insulating layers 33, and the conductive layers 32 and the insulating layers 33 are alternately disposed.

A first electrode 361a is formed on the upper and lower conductive layers 32 of the static electrode part 36, and a second electrode 361b is formed on the upper and lower conductive layers 32 of the static electrode part 36; the third electrode 351 is formed by connecting the two conductive layers 32 in the middle of the electrode portion 35. Corresponding differential driving voltages are applied to the first electrode 361a and the second electrode 361b respectively, and electrostatic driving acting forces are formed between the first electrode 361a and the third electrode 351 respectively, so that the moving electrode part 35 drives the diaphragm 2 to move in the up-down direction, and the MEMS speaker generates sound. In this embodiment, by applying a differential signal to the first electrode 361a and the second electrode 361b, a linear relationship between the driving force and the driving voltage can be obtained, and harmonic distortion caused by the driving voltage can be avoided.

Further, the electrostatic electrode portion 36 and the dynamic electrode portion 35 may have a multilayer structure, and the respective layers may be connected to each other so as to ensure that the first electrode 361a, the third electrode 351, and the second electrode 361b are formed to have facing portions or non-facing portions.

Referring to fig. 9, the second embodiment of the MEMS speaker performs out-of-plane motion, and the moving electrode part 35 is located between two conductive layers 32 on the static electrode part 36, and has a positive height part H and a positive length part L.

In other manners, one of the movable electrode 351 and the fixed electrode 361 includes a first electrode and a second electrode that are arranged in a direction perpendicular to the vibration direction of the diaphragm 2 and are electrically isolated, and the first electrode and the second electrode are used for connecting a differential signal. The other of the moving electrode 351 and the static electrode 361 includes a third electrode and a fourth electrode which are arranged along a direction perpendicular to the vibration direction of the diaphragm 2 and are electrically isolated, the third electrode is opposite to the first electrode in a matching manner, the fourth electrode is opposite to the second electrode in a matching manner, and the third electrode is electrically connected with the fourth electrode.

Referring to fig. 10 to 12, the third embodiment is different from the first embodiment in that partitions are provided on the static electrode portion 36 and the dynamic electrode portion 35. Specifically, the static electrode portion 36 is provided with a plurality of first partitions 362, the dynamic electrode portion 35 is provided with a plurality of second partitions 352, the first partitions 362 and the second partitions 352 are disposed correspondingly, and the first partitions 362 and the second partitions 352 are electrically isolated from each other; a first electrode 361a is formed by the communication between two adjacent conductive layers 32 on the upper part of one first partition 362, and a third electrode 351a is formed by the communication between two adjacent conductive layers 32 on the lower part of the corresponding second partition 352; the two conductive layers 32 adjacent to the lower portion of the first partition 362 adjacent to the first partition 362 are connected to each other to form a second electrode 361b, and the two conductive layers 32 adjacent to the upper portion of the second partition 352 are connected to each other to form a fourth electrode 351 b. The first electrode 361a and the second electrode 361b are connected to a differential signal, and the third electrode 351a and the fourth electrode 351b are electrically connected. In this embodiment, by applying a differential signal to the first electrode 361a and the second electrode 361b, a linear relationship between the driving force and the driving voltage can be obtained, and harmonic distortion caused by the driving voltage can be avoided. And compared with the second embodiment, the embodiment only needs 3 conductive layers, and the height of the device is reduced.

Preferably, the driving electrode part 3 is provided with a plurality of slits 38 to partition the first electrode 361a and the second electrode 361b and the third electrode 351a and the fourth electrode 351 b.

Preferably, the first electrodes 361a and the second electrodes 361b are equal in number, and the third electrodes 351a and the fourth electrodes 351b are equal in number.

The above are only embodiments of the present invention, and it should be noted that, for those skilled in the art, modifications can be made without departing from the inventive concept of the present invention, but these are all within the scope of the present invention.

Claims

The MEMS loudspeaker is characterized by comprising a base, a vibrating diaphragm positioned above the base and a driving electrode part arranged between the base and the vibrating diaphragm, wherein a driving electrode used for driving the vibrating diaphragm to vibrate along the vertical direction is formed on the driving electrode part;

the driving electrode part comprises at least three conductive layers and two insulating layers, the conductive layers and the insulating layers are alternately stacked to enable one insulating layer to be sandwiched between every two conductive layers, the driving electrode part is provided with a separation groove penetrating through all the conductive layers and all the insulating layers to separate the driving electrode part into an movable electrode part and a static electrode part, the movable electrode part and the vibrating diaphragm are relatively fixed, and the static electrode part and the base are relatively fixed;

the driving electrode comprises at least one movable electrode formed on the movable electrode part and at least one static electrode formed on the static electrode part, each movable electrode is formed by electrically connecting at least two conductive layers, each static electrode is formed by electrically connecting at least two conductive layers, at least one conductive layer is used for forming the movable electrode and the static electrode, at least one conductive layer is used for forming the movable electrode but not used for forming the static electrode, and at least one conductive layer is used for forming the static electrode but not used for forming the movable electrode.
2. The MEMS speaker as claimed in claim 1, wherein the driving electrode part comprises at least four conductive layers, and one of the moving electrode and the static electrode comprises a first electrode and a second electrode arranged in a vertical direction and electrically isolated from each other, and the first electrode and the second electrode are used for connecting a differential signal.
3. The MEMS speaker as claimed in claim 2, wherein the driving electrode part includes four conductive layers, the first electrode is formed on the upper two conductive layers, the second electrode is formed on the lower two conductive layers, and the static electrode is formed on the middle two conductive layers.
4. The MEMS loudspeaker of claim 1, wherein one of the moving electrode and the static electrode comprises a first electrode and a second electrode arranged in a direction perpendicular to a vibration direction of the diaphragm and electrically isolated from each other, and the first electrode and the second electrode are used for connecting a differential signal.
5. The MEMS speaker as claimed in claim 4, wherein the other of the moving electrode and the static electrode comprises a third electrode and a fourth electrode arranged in a direction perpendicular to the vibration direction of the diaphragm and electrically isolated from each other, the third electrode is in mating opposition with the first electrode, the fourth electrode is in mating opposition with the second electrode, and the third electrode and the fourth electrode are electrically connected.
6. The MEMS speaker of claim 4, wherein the conductive portion has a plurality of cuts formed therein to separate the first electrode from the second electrode and to separate the third electrode from the fourth electrode.
7. The MEMS speaker as claimed in claim 4, wherein the driving electrode part includes three conductive layers, the first electrode is formed of an upper two conductive layers, the second electrode is formed of a lower two conductive layers, the third electrode is formed of a lower two conductive layers, and the fourth electrode is formed of an upper two conductive layers.
8. The MEMS loudspeaker of claim 2 or 4, wherein the number of first electrodes and the number of second electrodes are equal.
9. The MEMS speaker of claim 1, wherein the separation groove is a castellated groove.
10. The MEMS speaker as claimed in claim 1, wherein the diaphragm includes a vibrating portion located in a central region and a fixing portion located at a periphery of the vibrating portion, the MEMS speaker further includes a connecting portion located between the driving electrode portion and the diaphragm, the connecting portion includes a first connecting portion and a second connecting portion that are spaced apart from each other, the first connecting portion is configured to connect the static electrode portion and the fixing portion, and the second connecting portion is configured to connect the dynamic electrode portion and the vibrating portion.
11. The MEMS speaker as claimed in claim 1, wherein the vibrating portion includes a dome portion at a center and a folded ring portion at a periphery of the dome portion, and the second connecting portion is configured to connect the dome portion and the moving electrode portion.
12. The MEMS speaker as claimed in claim 1, wherein the electrostatic electrode part includes a fixed end fixed to the base and an electrode terminal located inside the fixed end for forming the electrostatic electrode, and the first connection part is for connecting the fixed end and the fixed part.
13. The MEMS speaker as claimed in claim 1, wherein a cavity is opened at a center of the base, a first through hole communicating with the cavity is opened at a center of the driving electrode part, and a second through hole communicating with the first through hole is opened at a center of the connecting part.