CN118283511A - MEMS microphone and manufacturing method thereof - Google Patents

Abstract

The invention provides a MEMS microphone and a manufacturing method thereof. The MEMS microphone includes: the first bonding unit comprises a first vibrating diaphragm, a first backboard and a first connecting part, wherein the first backboard is provided with a first through hole, the first connecting part is positioned on the first surface of the first backboard, a first gap is formed between the first vibrating diaphragm and the first backboard and is connected with the first connecting part, and the first gap is communicated with the first through hole; the second bonding unit comprises a second vibrating diaphragm, a second backboard and a second connecting part, wherein the second backboard is provided with a second through hole, the second connecting part is positioned on the second surface of the second backboard, a second gap is formed between the second vibrating diaphragm and the second backboard and is connected with the second connecting part through the second connecting part, the second gap is communicated with the second through hole, and the first vibrating diaphragm is directly bonded and connected with the second vibrating diaphragm. The first bonding unit and the second bonding unit in the structure are manufactured by adopting similar processes, so that the number of masks in the process is reduced, the process flow is simplified, the process difficulty is reduced, and the large-scale mass production is simplified.

Description

MEMS microphone and manufacturing method thereof

Technical Field

The invention relates to the technical field of electronic devices, in particular to an MEMS microphone and a manufacturing method thereof.

Background

Microelectromechanical Systems (MEMS), also called microelectromechanical systems, microsystems, micromachines, etc., have evolved on the basis of microelectronics (semiconductor fabrication technology), incorporating high-tech electromechanical devices fabricated by photolithography, etching, thin film, LIGA, silicon micromachining, non-silicon micromachining, precision machining, etc. Common products include MEMS accelerometers, MEMS microphones, micro-motors, MEMS pressure sensors, and the like, and their integrated products.

Among them, the market for MEMS devices, particularly sensors, has been drastically increased by the development of consumer electronics, man-machine interaction, etc., and consumer markets typified by MEMS silicon microphones have been released, and the scale has been gradually expanded. However, in order to improve the sensitivity and the signal to noise ratio of the current MEMS silicon microphone, a plurality of microphones are connected in parallel to form array output, so that the longitudinal size and thickness of a device are increased, the process difficulty is increased, the improvement of the integration level of the device is not facilitated, and the mass production and cost reduction of the product are not facilitated.

Disclosure of Invention

The invention mainly aims to provide an MEMS microphone and a manufacturing method thereof, which are used for solving the problems of large process difficulty and unfavorable mass production of the MEMS microphone in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a MEMS microphone including: the first bonding unit comprises a first vibrating diaphragm, a first backboard and a first connecting part, wherein the first backboard is provided with a first through hole, the first connecting part is positioned on the first surface of the first backboard, a first gap is formed between the first vibrating diaphragm and the first backboard and is connected with the first connecting part, and the first gap is communicated with the first through hole; the second bonding unit comprises a second vibrating diaphragm, a second backboard and a second connecting part, wherein a second through hole is formed in the second backboard, the second connecting part is positioned on the second surface of the second backboard, a second gap is formed between the second vibrating diaphragm and the second backboard and is connected with the second connecting part through the second connecting part, the second gap is communicated with the second through hole, and the first vibrating diaphragm is directly bonded and connected with the second vibrating diaphragm.

Further, the first backplate has a third surface opposite the first surface, the second backplate has a fourth surface opposite the second surface, and the MEMS microphone further comprises: a first passivation layer covering the first surface and the third surface; and the second passivation layer covers the second surface and the fourth surface.

Further, the MEMS microphone further includes: the first substrate is arranged on one side of the first backboard, which is provided with the third surface, and a cavity penetrating along the direction close to the third surface is formed in the first substrate and communicated with the first through hole; and the third connecting part is connected with the first substrate and the first backboard.

Further, the MEMS microphone further includes: the electrodes are arranged on one side of the second backboard, which is provided with the fourth surface, and the electrodes are connected with the second backboard.

Further, the first connection portion and/or the second connection portion includes a first conductive portion and a second conductive portion, the first conductive portion has a first extending direction away from the first back plate, the second conductive portion has a second extending direction away from the first back plate, and the first extending direction intersect.

According to another aspect of the present invention, there is provided a method for manufacturing a MEMS microphone, including the steps of: forming a first bonding unit on a first substrate, wherein the first bonding unit comprises a first vibrating diaphragm, a first backboard and a first connecting part, a first through hole is formed in the first backboard, the first connecting part is positioned on the first surface of the first backboard, a first gap is formed between the first vibrating diaphragm and the first backboard and is connected through the first connecting part, and the first gap is communicated with the first through hole; providing a second bonding unit, wherein the second bonding unit comprises a second vibrating diaphragm, a second backboard and a second connecting part, a second through hole is formed in the second backboard, the second connecting part is positioned on the second surface of the second backboard, a second gap is formed between the second vibrating diaphragm and the second backboard and is connected with the second through the second connecting part, and the second gap is communicated with the second through hole; and directly bonding and connecting the first vibrating diaphragm and the second vibrating diaphragm.

Further, the step of forming the first bonding unit includes: forming a first support material on the first substrate to cover the first substrate; forming a first sub-passivation layer on a surface of the first support material away from the first substrate; forming a first backboard on one side of the first sub passivation layer away from the first substrate, wherein the first backboard is provided with a third surface opposite to the first surface; forming a second sub-passivation layer on one side of the first backboard far away from the first sub-passivation layer, wherein the first sub-passivation layer and the second sub-passivation layer jointly form a first passivation layer, the first passivation layer covers the first surface and the third surface, and a first through hole penetrating through the first sub-passivation layer, the first backboard and the second sub-passivation layer is formed; a first connecting portion and a first vibrating diaphragm are formed on one side of the second sub-passivation layer away from the first substrate.

Further, the step of forming the first connection portion and the first diaphragm includes: depositing a second supporting material on the second sub-passivation layer, so that part of the second supporting material covers the second sub-passivation layer, and the other part of the second supporting material is filled in the first through hole; forming a first connection hole sequentially penetrating the second support material and the second sub-passivation layer; and depositing a first vibrating diaphragm material on one side of the second supporting material far away from the first backboard, so that part of the first vibrating diaphragm material covers the surface of the second supporting material to form a first vibrating diaphragm, and the other part of the first vibrating diaphragm material is filled in the first connecting hole to form a first connecting part.

Further, the step of forming the second bonding unit includes: providing a second substrate, and forming a third sub-passivation layer on the second substrate; forming a second backboard on one side of the third sub passivation layer far away from the second substrate, wherein the second backboard is provided with a fourth surface opposite to the second surface; forming a fourth sub-passivation layer on one side of the second backboard far away from the third sub-passivation layer, wherein the third sub-passivation layer and the fourth sub-passivation layer jointly form a second passivation layer, the second passivation layer covers the second surface and the fourth surface, and a through second through hole is formed in the third sub-passivation layer, the second backboard and the fourth sub-passivation layer; forming a second connecting part and a second vibrating diaphragm on one side of the fourth sub-passivation layer far away from the second substrate; the second substrate is removed.

Further, the step of forming the second connection portion and the second diaphragm includes: depositing a third supporting material layer on the fourth sub-passivation layer, so that part of the third supporting material layer covers the fourth sub-passivation layer, and the other part of the third supporting material layer is filled in the second through hole; forming a second connection hole sequentially penetrating the third support material and the fourth sub-passivation layer; and depositing a second vibrating diaphragm material on one side of the third supporting material far away from the second backboard, so that part of the second vibrating diaphragm material covers the surface of the third supporting material to form a second vibrating diaphragm, and the other part of the second vibrating diaphragm material is filled in the second connecting hole to form a second connecting part.

Further, the manufacturing method further comprises the following steps: forming a plurality of electrode openings in the third sub-passivation layer through to the second backplate; electrode material is deposited in each electrode opening to form an electrode, which is connected to a second backplate.

Further, the manufacturing method further comprises the following steps: after the step of directly bonding and connecting the first diaphragm and the second diaphragm, sequentially etching a part of the first substrate and a part of the first support material to form a cavity penetrating in a direction close to the third surface and communicating with the first through hole, forming a first support layer by the remaining first support material, removing the second support material positioned in the first through hole and the third support material positioned in the second through hole, and forming a second support layer by the remaining second support material and a third support layer by the remaining third support material, wherein the second support material and the third support material respectively correspond to the cavity.

By applying the technical scheme of the application, the MEMS microphone is provided, and comprises: the first bonding unit comprises a first vibrating diaphragm, a first backboard and a first connecting part, wherein the first backboard is provided with a first through hole, the first connecting part is positioned on the first surface of the first backboard, a first gap is formed between the first vibrating diaphragm and the first backboard and is connected with the first connecting part, and the first gap is communicated with the first through hole; the second bonding unit comprises a second vibrating diaphragm, a second backboard and a second connecting part, wherein a second through hole is formed in the second backboard, the second connecting part is positioned on the second surface of the second backboard, a second gap is formed between the second vibrating diaphragm and the second backboard and is connected with the second backboard through the second connecting part, the second gap is communicated with the second through hole, and the first vibrating diaphragm is directly bonded and connected with the second vibrating diaphragm. The MEMS microphone comprises a first bonding unit and a second bonding unit which are independent, and the first vibrating diaphragm and the second vibrating diaphragm in the first bonding unit are directly bonded, so that the MEMS microphone is formed, wherein the first vibrating diaphragm and the second vibrating diaphragm form a new vibrating diaphragm of the MEMS microphone. Compared with the process flow of manufacturing each membrane layer of the MEMS microphone in the prior art, the MEMS microphone is obtained by forming the first bonding unit and the second bonding unit and adopting the mode of directly bonding the first vibrating membrane and the second vibrating membrane, the problems of difficult stress control and larger process difficulty of the MEMS microphone caused by the formation of the structural layer and the increase of the longitudinal height of each membrane layer along the direction vertical to the back plate can be avoided, and the first bonding unit and the second bonding unit in the structure are manufactured by adopting similar process flows, so that the process flow of complex sequences can be greatly simplified, and the mask number in the manufacturing process is reduced, thereby greatly reducing the process difficulty and enabling the large-scale mass production of the MEMS microphone to be simpler.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:

Fig. 1 is a schematic cross-sectional structure of an embodiment of a MEMS microphone according to the present invention;

Fig. 2 is a schematic cross-sectional view illustrating a first bonding unit formed in a method for manufacturing a MEMS microphone according to the present invention;

Fig. 3 is a schematic cross-sectional view showing a structure of a second bonding unit formed in a method for manufacturing a MEMS microphone according to the present invention;

fig. 4 is a schematic cross-sectional view showing the structure of the substrate after bonding the first bonding unit and the second bonding unit.

Wherein the above figures include the following reference numerals:

10. A first substrate; 101. a second substrate; 20. a first back plate; 30. a first connection portion; 40. a vibrating diaphragm; 401. a first diaphragm; 402. a second diaphragm; 50. a second connecting portion; 60. a second back plate; 70. a first passivation layer; 701. a first sub-passivation layer; 702. a second sub-passivation layer; 80. a second passivation layer; 801. a third sub-passivation layer; 802. a fourth sub-passivation layer; 90. a first support layer; 901. a first support material; 100. a second support layer; 102. a second support material; 110. a third support layer; 111. a third support material; 120. an electrode; 130. a first through hole; 140. a second through hole; 150. a first void; 160. a second void; 170. a cavity; 180. and a third connecting part.

Detailed Description

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the invention herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

As mentioned in the background, as the market for MEMS devices, particularly sensors, has increased dramatically, consumer markets, typified by MEMS silicon microphones, have been released and the scale has gradually increased. However, because the high-end performance silicon microphone products are fewer and mainly concentrated in foreign manufacturers, the current main MEMS microphone in the market has the problem of oversized size, the application occasions are limited, and the number of main tube cores on a single wafer is reduced along with the increase of the size, so that the cost of the single chip is increased sharply, and the large-scale production is not facilitated.

To solve the above technical problem, according to an aspect of the present invention, there is provided a MEMS microphone, as shown in fig. 1, including: a first bonding unit including a first diaphragm 401, a first back plate 20, and a first connection portion 30, wherein the first back plate 20 has a first through hole 130 therein, the first connection portion 30 is positioned on a first surface of the first back plate 20, a first gap 150 is formed between the first diaphragm 401 and the first back plate 20 and connected through the first connection portion 30, and the first gap 150 communicates with the first through hole 130; and a second bonding unit including a second diaphragm 402, a second back plate 60, and a second connection portion 50, wherein the second back plate 60 has a second through hole 140 therein, the second connection portion 50 is positioned on a second surface of the second back plate 60, a second gap 160 is formed between the second diaphragm 402 and the second back plate 60 and is connected through the second connection portion 50, the second gap 160 communicates with the second through hole 140, and the first diaphragm 401 is directly bonded to the second diaphragm 402.

Compared with the existing multilayer capacitive MEMS microphone with the double-layer vibrating diaphragm and the double-layer backboard, the manufacturing process of the existing structure is that the film layers are continuously stacked upwards on the basis of the traditional single-layer MEMS microphone, and the manufacturing process modules are repeatedly increased, so that the manufacturing process difficulty is rapidly increased due to the influence of the problems of stress and the like along with the increase of the thickness of the device, and the yield of the device is difficult to control. Therefore, in the MEMS microphone structure of the present invention, the first bonding unit and the second bonding unit are formed by using similar processes, and the first bonding unit and the second bonding unit have the first diaphragm 401 and the second diaphragm 402, respectively, and the first bonding unit and the second bonding unit are connected by directly bonding the first diaphragm 401 and the second diaphragm 402 in the first bonding unit, so as to form the MEMS microphone, wherein a new film layer formed by bonding the first diaphragm 401 and the second diaphragm 402 is the MEMS microphone device diaphragm 40; because the first bonding unit and the second bonding unit in the MEMS microphone are independent structures manufactured by adopting similar processes, for the multi-layer capacitive MEMS microphone structure forming the double-layer backboard, the complex process flow is simplified, the manufacturing process difficulty is reduced, and meanwhile, the mask number during manufacturing is reduced, so that the process difficulty is greatly reduced, and the large-scale mass production of the MEMS microphone is simpler.

The first back plate 20, the first diaphragm 401, the first connection portion 30, the second back plate 60, the second diaphragm 402, and the second connection portion 50 are formed of any one of the following materials: polysilicon, an additional polysilicon layer on silicon nitride, an additional metal layer on silicon nitride, etc. Illustratively, the material forming the first and second backplates 20, 60 comprises doped polysilicon. Wherein silicon is essentially resistant to the high temperature environment required for surface mounting, while its packaging structure reduces the overall height of such a microphone system, while MEMS microphones are very stable in performance at different temperatures and sensitive to temperature, vibration, humidity and time, since no charge is present therein and substantially no deformation is present when subjected to external load impacts. And the doped polysilicon material has stronger heat resistance, so that the MEMS microphone can bear high-temperature reflow soldering at 260 ℃ without any change in performance.

In addition, in order to form a capacitance output between the first back plate 20 and the first diaphragm 401 and between the second back plate 60 and the second diaphragm 402, a first gap 150 is formed between the first back plate 20 and the first diaphragm 401, and a second gap 160 is formed between the second back plate 60 and the second diaphragm 402, so that air can pass through the first through hole 130, the first gap 150, the second through hole 140 and the second gap 160 on the first back plate 20, wherein after the first diaphragm 401 and the second diaphragm 402 are bonded, ohmic contact is formed on the diaphragm 40, and under the pressure of sound waves, the diaphragm 40 is displaced due to the air pressure change caused by the sound waves, and the positions of the first back plate 20 and the second back plate 60 are not changed. During the movement of the diaphragm 40, the distance between the diaphragm 40 and the first and second back plates 20 and 60 may change, eventually resulting in a change in the capacitance between the first and second back plates 20 and 40 and between the second back plate 60 and 40, thereby forming a capacitive output. And the first connection part 30 is provided to connect the first back plate 20 and the first diaphragm 401, the second connection part 50 is provided to connect the second back plate 60 and the second diaphragm 402, so that the first back plate 20, the first connection part 30, the diaphragm 40, the second connection part 50 and the second back plate 60 can be electrically connected, and thus the lower layer output is led out to the surface to form a pad (bonding pad).

In some alternative embodiments, the first backplate 20 has a third surface opposite the first surface, the second backplate 60 has a fourth surface opposite the second surface, and the MEMS microphone further comprises: a first passivation layer 70, the first passivation layer 70 covering the first surface and the third surface; and a second passivation layer 80, the second passivation layer 80 covering the second surface and the fourth surface.

In the above embodiment, since the characteristics, stability and reliability of the semiconductor device are closely related to the surface properties of the semiconductor, in order to avoid the influence of the environment and other external factors on the first backplate 20 and the second backplate 60 in the MEMS microphone, the first surface and the third surface of the first backplate 20 and the second surface and the fourth surface of the second backplate 60 are covered with a passivation film, respectively, the passivation films on the first surface and the third surface of the first backplate 20 are used as the first passivation layer 70, and the passivation films on the second surface and the fourth surface of the second backplate 60 are used as the second passivation layer 80.

The materials of the first passivation layer 70 and the second passivation layer 80 may include silicon nitride, boron nitride, silicon carbide, and the like. In some alternative embodiments, the materials of the first passivation layer 70 and the second passivation layer 80 are silicon nitride, which is a good insulating medium, and has compact structure, high hardness, high dielectric strength, stable chemical property, and little reaction with any acids, and can provide a rigid back plate, provide stress support for the first back plate 20 and the second back plate 60, and avoid the short circuit between the first back plate 20 and/or the second back plate 60 and the diaphragm 40.

In some alternative embodiments, as shown in fig. 1, the MEMS microphone further comprises: a first substrate 10, the first substrate 10 being disposed on a side of the first back plate 20 having the third surface, and the first substrate 10 having a cavity 170 penetrating therethrough in a direction approaching the third surface, the cavity 170 being in communication with the first through hole 130; and a third connection part 180, the third connection part 180 connecting the first substrate 10 and the first back plate 20.

In the above embodiment, the material of the first substrate includes single crystal silicon, and further alternatively, the crystal orientation of the single crystal silicon is <100>. Through forming the through cavity 170 in the first substrate 10 in a direction close to the third surface, the cavity 170 is penetrated to the third surface of the first back plate 20, so that the plurality of first through holes 130 on the first back plate 20 are all communicated with the cavity 170, and thus the communication among the cavity 170, the first through holes 130, the first gap 150, the second gap 160 and the second through holes 140 is achieved, as shown in fig. 1, the cavity 170, the first through holes 130, the first gap 150, the second gap 160 and the second through holes 140 are communicated through the air release holes on the diaphragm 40, so that when the first diaphragm 401 and the second diaphragm 402 are subjected to instantaneous high air pressure, the air pressure can be quickly released through the air release holes, and the pressure balance of the first diaphragm 401 and the second diaphragm 402 is maintained, the first diaphragm 401 and the second diaphragm 402 are prevented from being damaged, and the yield and the reliability of the MEMS microphone are further ensured.

In the above embodiment, the MEMS microphone further includes a third connection portion 180, and the third connection portion 180 is used to connect the first back plate 20 and the first substrate 10, so as to achieve a grounding effect.

In some alternative embodiments, the MEMS microphone further comprises: the plurality of electrodes 120 includes a first sub-electrode, a second sub-electrode, a third sub-electrode, and a fourth sub-electrode sequentially disposed at a side of the second back plate 60 having the fourth surface in the C-C' direction with a certain interval, and the sub-electrodes are electrically isolated from each other. In this embodiment, since the second backplate 60 includes the first, second, third, and fourth sub-backplates sequentially disposed in the C-C ' direction and electrically isolated from each other, the first backplate 20 includes the fifth and sixth sub-backplates sequentially disposed in the C-C ' direction and electrically isolated from each other, and the diaphragm 40 includes the first, second, and third sub-diaphragms sequentially disposed in the C-C ' direction and electrically isolated from each other. Further alternatively, the first connection portions 30 and the second connection portions 50 are each a plurality of spaced apart along the C-C' direction, and each of the first connection portions 30 is electrically isolated from each other, and each of the second connection portions 50 is electrically isolated from each other.

In the above embodiment, the first sub-electrode, the first sub-back plate, the second connection portion 50 near the first sub-electrode, the diaphragm 40, the first connection portion 30, the first back plate 20, and the third connection portion 180 are electrically connected to achieve grounding; the second sub-electrode is electrically connected with the second sub-back plate to realize that the output of the second back plate 60 is led to the surface; the third sub-electrode, the second connection part 50 close to the third sub-electrode and the vibrating diaphragm 40 are electrically connected to realize that the output of the vibrating diaphragm 40 is led to the surface; the fourth sub-electrode, the second connection portion 50 adjacent to the fourth sub-electrode, the diaphragm 40, and the first connection portion 30 are electrically connected to achieve the purpose of guiding the output of the first back plate 20 to the surface. In some alternative embodiments, each first connection portion 30 and/or each second connection portion 50 includes a first conductive portion having a first direction of extension away from the first back plate 20 and a second conductive portion having a second direction of extension away from the first back plate 20, the first direction of extension intersecting the first direction of extension. Further alternatively, the first connection portion 30 is disposed in a V shape along a direction away from the first back plate 20 to connect the first back plate 20 and the first diaphragm 401, and the second connection portion 50 is disposed in a V shape along a direction away from the second back plate 60 to connect the second back plate 60 and the second diaphragm 402.

In the above embodiment, each of the first connection portions 30 includes the first conductive portion and the second conductive portion for connecting the first back plate 20 and the first diaphragm 401, wherein the first conductive portion and the second conductive portion have different extending directions along the direction away from the first back plate 20, that is, the extending direction of the first conductive portion is taken as the first extending direction and the extending direction of the second conductive portion is taken as the second extending direction along the direction away from the first back plate 20, and the first extending direction and the second extending direction always intersect at a point. Similarly, each second connection portion 50 also includes a first conductive portion and a second conductive portion, where the first conductive portion has a first extending direction away from the second back plate 60, and the second conductive portion has a second extending direction away from the second back plate 60, and on the extending lines of the first extending direction and the second extending direction, the first conductive portion and the second conductive portion always meet at a point. By adopting the first connecting portion 30 and the second connecting portion 50 of the above structure, the process difficulty can be reduced because the slopes of the respective first connecting portion 30 and second connecting portion 50 are gentle.

According to another aspect of the present invention, there is also provided a method for manufacturing a MEMS microphone, the method comprising the steps of: forming a first bonding unit on a first substrate, wherein the first bonding unit comprises a first vibrating diaphragm, a first backboard and a first connecting part, a first through hole is formed in the first backboard, the first connecting part is positioned on the first surface of the first backboard, a first gap is formed between the first vibrating diaphragm and the first backboard and is connected through the first connecting part, and the first gap is communicated with the first through hole; providing a second bonding unit, wherein the second bonding unit comprises a second vibrating diaphragm, a second backboard and a second connecting part, a second through hole is formed in the second backboard, the second connecting part is positioned on the second surface of the second backboard, a second gap is formed between the second vibrating diaphragm and the second backboard and is connected with the second through the second connecting part, and the second gap is communicated with the second through hole; and directly bonding and connecting the first vibrating diaphragm and the second vibrating diaphragm.

In the manufacturing method, the first bonding unit and the second bonding unit are formed by adopting similar processes, and then the first vibrating diaphragm in the first bonding unit and the second vibrating diaphragm in the second bonding unit are bonded and connected in a direct bonding mode, so that the complete MEMS microphone is formed.

Exemplary embodiments of a method of fabricating a MEMS microphone provided according to the present application will be described in more detail below. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It should be appreciated that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of these exemplary embodiments to those skilled in the art.

First, a first bonding unit including a first diaphragm 401, a first back plate 20, and a first connection portion 30 is formed on a first substrate, as shown in fig. 2.

In some alternative embodiments, the step of forming the first bonding unit comprises: forming a first support material 901 on the first substrate 10 to cover the first substrate 10, and forming a first sub-passivation layer 701 on a surface of the first support material 901 remote from the first substrate 10; forming a first back plate 20 on a side of the first sub-passivation layer 701 remote from the first substrate 10, the first back plate 20 having a third surface opposite to the first surface; forming a second sub-passivation layer 702 on a side of the first back plate 20 away from the first sub-passivation layer 701, wherein the first sub-passivation layer 701 and the second sub-passivation layer 702 together form a first passivation layer 70, the first passivation layer 70 covers the first surface and the third surface, and a first through hole 130 penetrating the first sub-passivation layer 701, the first back plate 20 and the second sub-passivation layer 702 is formed; the first connection portion 30 and the first diaphragm 401 are formed at a side of the second sub-passivation layer 702 remote from the first substrate 10. By forming the first sub-passivation layer 701 and the second sub-passivation layer 702 on both sides of the first diaphragm 401, the first sub-passivation layer 701 and the second sub-passivation layer 702 play roles in reinforcing the back plate and blocking, and protect the first back plate 20, so that the whole back plate forms a rigid back plate, and is basically free from deformation under the impact of external load.

Specifically, the step of forming the first bonding unit includes: first, a first substrate 10 is provided, the first substrate 10 includes single crystal silicon, and after the first substrate 10 is formed, a first support material 901 may be deposited on the first substrate 10 by a conventional semiconductor process method such as thermal oxidation or Low Pressure Chemical Vapor Deposition (LPCVD) or plasma enhanced chemical deposition (PECVD), such that the first support material 901 covers the first substrate 10, and further, a first sub-passivation layer 701, a first back plate 20, a second sub-passivation layer 702, and a first diaphragm 401 are sequentially formed on a side of the first support material 901 away from the first substrate 10 to form a first bonding unit, wherein the first support material 901 may be silicon oxide, and the first back plate 20 is isolated from the first substrate 10 by the first support material 901.

Wherein, a layer of first sub-passivation material is deposited on the side of the first support material 901 far from the first substrate 10 through a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD) or plasma enhanced chemical deposition (PECVD), a first back plate material is formed on the side of the first sub-passivation material far from the first substrate 10 through a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD), and a second sub-passivation material is deposited on the side of the first back plate material far from the first substrate 10 through a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD) or plasma enhanced chemical deposition (PECVD); the above-described first sub-passivation material, first back plane material, and second sub-passivation material are patterned by photolithography and etching processes or the like to form a first sub-passivation layer 701 having a plurality of first openings, a first back plane 20 having a plurality of first through holes 130, and a second sub-passivation layer 702 having a plurality of second openings, the first back plane 20 being isolated by the plurality of first through holes 130, i.e., the first back plane 20 includes a fifth sub-back plane and a sixth sub-back plane sequentially arranged in the C-C' direction and electrically isolated from each other. Wherein, each first opening, each first through hole 130 and each second opening are arranged in a one-to-one correspondence and are communicated with each other.

For example, the thicknesses of the first and second sub-passivation layers 701 and 702 may be 0.2 to 1 μm, and the thickness of the first back plate 20 may be 0.3 to 1 μm.

In some alternative embodiments, the step of forming the first connection portion 30 and the first diaphragm 401 includes: depositing a second support material 102 on the second sub-passivation layer 702 such that a portion of the second support material 102 covers the second sub-passivation layer 702 and another portion of the second support material 102 fills the first via 130; forming a first connection hole sequentially penetrating the second support material 102 and the second sub-passivation layer 702; depositing a first vibrating film material on one side of the second supporting material 102 far away from the first back plate 20, so that part of the first vibrating film material covers the surface of the second supporting material 102 to form a first vibrating film 401, and the other part of the first vibrating film material is filled in the first connecting hole to form a first connecting part 30; by depositing the second support material 102 between the first diaphragm 401 and the first backplate 20, the first diaphragm 401 is electrically isolated from the first backplate 20 and a secure connection of the device is achieved.

In the above embodiment, the second support material 102 may be deposited on the side of the first back plate 20 away from the second sub-passivation layer 702 by a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD) or plasma enhanced chemical deposition (PECVD).

Specifically, the second sub-passivation layer 702, the first back plate 20 and the first sub-passivation layer 701 on the first substrate 10 have a second opening, a first through hole 130 and a first opening, respectively, so that when the second support material 102 is deposited, the second support material 102 covers a side of the second sub-passivation layer 702 away from the first back plate 20, and another portion of the second support material 102 fills the second opening, the first through hole 130 and the first opening; then, the second supporting material 102 and the second sub-passivation layer 702 are patterned by photolithography and etching processes, so as to form a plurality of first connection holes sequentially penetrating the second supporting material 102 and the second sub-passivation layer 702, a first diaphragm material is deposited on a side of the second supporting material 102 far from the first back plate 20 by a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD), and the first diaphragm material is etched, and a vent hole is formed on the first diaphragm material so that a portion of the first diaphragm material covers the surface of the second supporting material 102 to form a first diaphragm 401, wherein the first diaphragm 401 includes a portion of the first sub-diaphragm, a portion of the second sub-diaphragm, and a portion of the third sub-diaphragm, which are sequentially arranged in the C-C' direction and electrically isolated from each other, and another portion of the first diaphragm material is filled in the first connection holes to form the first connection portions 30. Wherein the second support material 102 comprises silicon oxide, and the thickness of the first diaphragm 401 is 0.2-1 μm.

In some alternative embodiments, an oxide layer material is deposited on the side of the first diaphragm 401 away from the second support material 102 by a deposition process such as plasma enhanced chemical vapor deposition (LPCVD), and the oxide layer material is polished by a Chemical Mechanical Polishing (CMP) process to expose the first diaphragm 401, as shown in fig. 2, wherein the thickness of the oxide layer material is 0.5-3 μm. In this example, the oxide layer material is deposited first, so that the oxide layer material backfills the uneven surface area of the first diaphragm 401, and the oxide layer material may be the same as the material of the second support material 102, and then the first surface of the first diaphragm 401 is polished by using a chemical mechanical polishing process, so that the first diaphragm 401 and the second diaphragm 402 can be more bonded during bonding connection.

The second bonding unit including the second diaphragm 402, the second back plate 60, and the second connection part 50 is formed before the step of forming the first bonding unit described above or after the step of forming the first bonding unit described above, as shown in fig. 3.

In some alternative embodiments, the step of forming the second bonding unit comprises: providing the second substrate 101, forming the third sub-passivation layer 801 on the second substrate 101, or forming the third sub-passivation layer 801 on the second substrate 101, further including depositing a first support material 901 on the second substrate 101, and then forming the third sub-passivation layer 801 on the first support material 901, as shown in fig. 3; then forming a second back plate 60 on a side of the third sub-passivation layer 801 remote from the second substrate 101, the second back plate 60 having a fourth surface opposite to the second surface; forming a fourth sub-passivation layer 802 on a side of the second back plate 60 away from the third sub-passivation layer 801, the third sub-passivation layer 801 and the fourth sub-passivation layer 802 together forming a second passivation layer 80, the second passivation layer 80 covering the second surface and the fourth surface and forming a second through hole 140 penetrating the third sub-passivation layer 801, the second back plate 6 and the fourth sub-passivation layer 802; forming a second connection portion 50 and a second diaphragm 402 on a side of the fourth sub-passivation layer 802 remote from the second substrate 101; the second substrate 101 is removed. By forming the third sub-passivation layer 801 and the fourth sub-passivation layer 802 on both sides of the second diaphragm 402, the third sub-passivation layer 801 and the fourth sub-passivation layer 802 play a role in reinforcing the backplate and blocking, and protect the second backplate 60, so that the entire backplate forms a rigid backplate, and is substantially free from deformation under the impact of external load.

Specifically, the step of forming the second bonding unit may include: providing a second substrate 101, wherein the second substrate 101 comprises single crystal silicon, and the crystal orientation of the single crystal silicon is <100>, depositing a layer of a third sub-passivation material or depositing a first support material 901 and a third sub-passivation material on one side of the second substrate 101 by a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD) or plasma enhanced chemical deposition (PECVD), then depositing a second back plate 60 material on one side of the third sub-passivation layer material away from the second substrate 101 by a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD), then depositing a fourth sub-passivation material on one side of the second back plate material away from the second substrate 101 by a deposition process such as Low Pressure Chemical Vapor Deposition (LPCVD) or plasma enhanced chemical deposition (PECVD); the third sub-passivation material, the second back plate material, and the fourth sub-passivation material are patterned by photolithography and etching processes or the like to form a third sub-passivation layer 801 having a plurality of third openings, a second back plate 60 having a plurality of second through holes 140, and a fourth sub-passivation layer 802 having a plurality of fourth openings, the second back plate 60 being isolated by the plurality of second through holes 140, and then the second back plate 60 includes a first sub-back plate, a second sub-back plate, a third sub-back plate, and a fourth sub-back plate sequentially disposed in the C-C' direction and electrically isolated from each other. Wherein, each third opening, each second through hole 140 and each fourth opening are arranged in a one-to-one correspondence and are communicated with each other.

Illustratively, the thickness of the third sub-passivation layer 801 and the fourth sub-passivation layer 802 is 0.2 μm to 1 μm, and the thickness of the second back plate 60 is 0.3 μm to 1 μm.

In some alternative embodiments, the second substrate 101 and the first support material 901 are removed by using a thinning process or a Chemical Mechanical Polishing (CMP) process, so as to expose the third sub-passivation layer 801, and then an electrode 120 penetrating to the second backplate 60 is formed in the third sub-passivation layer 801, so as to implement extraction of the backplate.

In some alternative embodiments, the step of forming the second connection 50 and the second diaphragm 402 includes: depositing a third supporting material 111 layer on the fourth sub-passivation layer 802, such that a portion of the third supporting material 111 layer covers the fourth sub-passivation layer 802 and another portion of the third supporting material 111 fills the second through hole 140; forming a second connection hole sequentially penetrating the third support material 111 and the fourth sub-passivation layer 802; the second diaphragm material is deposited on the side of the third support material 111 away from the second back plate 60, so that a part of the second diaphragm material covers the surface of the third support material 111 to form a second diaphragm 402, and another part of the second diaphragm material is filled in the second connection hole to form the second connection portion 50.

Illustratively, the third support material 111 is deposited on the side of the fourth sub-passivation layer 802 remote from the first backplate 20 by conventional semiconductor process fabrication methods such as Low Pressure Chemical Vapor Deposition (LPCVD) or plasma enhanced chemical deposition (PECVD). By depositing the third support material 111 between the second diaphragm 402 and the second backplate 60, the second diaphragm 402 and the second backplate 60 are electrically isolated and a secure connection of the device is achieved.

Specifically, the third sub-passivation layer 801, the second back plate 60, and the fourth sub-passivation layer 802 on the second substrate 101 have a third opening, a second through hole 140, and a fourth opening, respectively, so that when the third supporting material 111 is deposited, the third supporting material 111 covers a side of the fourth sub-passivation layer 802 away from the second back plate 60, and another portion of the third supporting material 111 fills the third opening, the second through hole 140, and the fourth opening; then, the third support material 111 and the fourth sub-passivation layer 802 are patterned by photolithography and etching processes, etc., to form a plurality of second connection holes penetrating through the third support material 111 and the fourth sub-passivation layer 802 sequentially in the C-C ' direction, the plurality of second connection holes are electrically isolated, a second diaphragm material is deposited on a side of the third support material 111 away from the second back plate 60 by a conventional semiconductor process such as Low Pressure Chemical Vapor Deposition (LPCVD), etc., and the second diaphragm material is etched, air leakage holes are formed on the second diaphragm material, so that a portion of the second diaphragm material covers the surface of the third support material 111 to form a second diaphragm 402, the second diaphragm 402 includes a portion of the first sub-diaphragm, a portion of the second sub-diaphragm, and a portion of the third sub-diaphragm, which are sequentially disposed in the C-C ' direction and electrically isolated from each other, and another portion of the second diaphragm material is filled in the second connection holes to form second connection portions 50, and each of the second connection portions 50 is electrically isolated in the C-C ' direction.

The third supporting material 111 may include silicon oxide, and the second diaphragm 402 may have a thickness of 0.2 to 1 μm.

In the above embodiment, after the first bonding unit and the second bonding unit are formed, the first diaphragm 401 and the second diaphragm 402 are directly bonded, C-C 'is the bonding surface of the first diaphragm 401 and the second diaphragm 402, and then a part of the first sub-diaphragm, a part of the second sub-diaphragm and a part of the third sub-diaphragm of the first diaphragm 401, and a part of the first sub-diaphragm, a part of the second sub-diaphragm and a part of the third sub-diaphragm of the second diaphragm 402 together form the diaphragm 40, and then the diaphragm 40 includes the first sub-diaphragm, the second sub-diaphragm and the third sub-diaphragm that are sequentially arranged along the direction of C-C' and are electrically isolated from each other, as shown in fig. 4, further optionally, the third supporting material 111 located in the second through hole 140 is removed, and the third supporting material 111 located in the third opening of the third sub-passivation layer 801 and the fourth opening of the fourth sub-passivation layer 802 is removed, so that the second through hole 140, the third opening and the fourth opening are communicated to form the sound hole.

In some alternative embodiments, an oxide layer material is deposited on the side of the second diaphragm 402 away from the third support material 111 by a conventional semiconductor process such as plasma enhanced chemical vapor deposition (LPCVD), such that the oxide layer material backfills the uneven surface area of the second diaphragm 402, and the oxide layer material is polished by a Chemical Mechanical Polishing (CMP) process to expose the second diaphragm 402, wherein the oxide layer has a thickness of 0.5-3 μm. In this embodiment, the oxide layer material may be the same as the material of the third support material 111, and the second surface of the second diaphragm 402 is polished by using a chemical mechanical polishing process, so that the first diaphragm 401 and the second diaphragm 402 may be more bonded during bonding connection, as shown in fig. 3.

In some optional embodiments, the above manufacturing method of the present invention further includes: forming a plurality of electrode 120 openings in the third sub-passivation layer 801 through to the second backplate 60; electrode 120 material is deposited in each electrode 120 opening to form an electrode 120, the electrode 120 being connected to the second backplate 60. In the above embodiment, the third sub-passivation layer 801 may be patterned by photolithography and etching, etc. to form a lead hole penetrating the third sub-passivation layer 801 to the electrode 120 of the second back plate 60, after forming the lead hole of the electrode 120, the electrode 120 material is deposited by using a conventional semiconductor process technology such as sputtering, etc., and the electrode 120 material is patterned again by photolithography and etching, etc. to form the electrode 120. The plurality of electrodes 120 are formed in the MEMS microphone such that the plurality of electrodes 120 are electrically connected to the second back plate 60, thereby realizing the extraction of the back plate.

The electrode 120 may include a plurality of sub-electrodes, where the first sub-electrode is electrically connected to the second back plate 60, the second connection portion 50, the second diaphragm 402, the first diaphragm 401, the first connection portion 30, the first back plate 20, and the first substrate 10, the second sub-electrode is electrically connected to the second back plate 60, the third sub-electrode is electrically connected to the second back plate 60, the second connection portion 50, the second diaphragm 402, and the first diaphragm 401, and the fourth sub-electrode is electrically connected to the second back plate 60, the second connection portion 50, the second diaphragm 402, the first diaphragm 401, the first connection portion 30, and the first back plate 20.

In some alternative embodiments, the first bonding unit includes a first back plate 20 and a diaphragm 40, where the first back plate 20 is located on the first substrate 10, the diaphragm 40 is located on a side of the first back plate 20 away from the first substrate 10, a first support layer 90 and a first sub-passivation layer 701 are further located between the first back plate 20 and the first substrate 10, the first sub-passivation layer 701 is located on a side of the first support layer 90 away from the first substrate 10, a second sub-passivation layer 702 and a second support layer 100 are further located between the first back plate 20 and the diaphragm 40, and the second support layer 100 is located on a side of the second sub-passivation layer 702 away from the first back plate 20; the second bonding unit includes a second back plate 60, where the second back plate 60 is disposed on a side of the diaphragm 40 away from the first back plate 20, and a fourth sub-passivation layer 802 and a third supporting layer 110 are further disposed between the diaphragm 40 and the second back plate 60, and the third supporting layer 110 is disposed on a side of the fourth sub-passivation layer 802 away from the second back plate 60.

In the above-mentioned embodiment, in the process of forming the MEMS microphone, the first supporting layer 90 is first formed on the first substrate 10, then the first sub-passivation layer 701 is formed on the side of the first supporting layer 90 away from the first substrate 10, then the first back plate 20 is formed on the side of the first sub-passivation layer 701 away from the first supporting layer 90, and the second sub-passivation layer 702 is formed on the side of the first back plate 20 away from the first sub-passivation layer 701, the second sub-passivation layer 702, the first back plate 20 and the first sub-passivation layer 701 are sequentially etched to form the first through hole 130, then the second supporting layer 100 is formed on the side of the second sub-passivation layer 702 away from the first back plate 20, and then the first through hole 130 is filled with the second supporting material for the second supporting layer 100, and then the diaphragm 40 is formed on the side of the second supporting layer 100 away from the second sub-passivation layer 702, and the diaphragm 40 is etched to form three sub-diaphragms 40 arranged at intervals, and the diaphragm 40 is filled with the second supporting material for the interval region between the adjacent two sub-diaphragms 40. In addition, the same process steps are adopted to form the second back plate 60 on the second substrate 101, so that two sides of the second back plate 60 are contacted and provided with a third sub passivation layer 801 and a fourth sub passivation layer 802, a second through hole 140 is formed in the third sub passivation layer, the second back plate 60 and the fourth sub passivation layer 802, a third supporting layer 110 is formed on one side of the fourth sub passivation layer 802 far away from the second back plate 60, the second through hole 140 is filled with a third supporting material of the third supporting layer 110, then the diaphragm 40 of the first bonding unit and the third supporting layer 110 of the second bonding unit are connected in a bonding mode, after bonding connection, a part of the fourth sub passivation layer 802 far away from one side of the second back plate 60 is removed, the part comprises the second substrate 101, and further a first electrode, a second electrode and a third electrode are respectively formed by etching, wherein the first electrode is directly connected with the first substrate 20, the second electrode is directly connected with the diaphragm 40, the third electrode is directly connected with the second substrate 60, and the diaphragm 40 is further connected with the second substrate 60, and the microphone is further connected with the microphone through hole 130, the microphone is manufactured in a large-size, and the microphone is more difficult, and the process is reduced, and the microphone is more difficult, and the microphone is manufactured.

In another embodiment, a third supporting layer 110 is further provided on a side of the diaphragm 40 away from the first backplate 20 in the first bonding unit, and in the process of forming the MEMS microphone, the third supporting layer 110 of the first bonding unit and the third supporting layer 110 of the second bonding unit are connected by bonding, so that the first bonding unit and the second bonding unit form a stable connection, after the bonding connection, a portion of the fourth sub-passivation layer 802 on a side away from the second backplate 60 is removed, and the portion includes the second substrate 101, so that a first electrode, a second electrode and a third electrode are respectively etched, where the first electrode is directly connected with the first backplate 20, the second electrode is directly connected with the diaphragm 40, and the third electrode is directly connected with the second backplate 60, so that after the first through hole 130 and the second through hole 140 are connected to the cavity of the first substrate 10, the MEMS microphone is formed, and the manufacturing process becomes greatly reduced, so that the manufacturing process becomes simpler and the manufacturing process becomes simpler.

In some alternative embodiments, the method of making further comprises: after the step of directly bonding the first diaphragm 401 and the second diaphragm 402 along the C-C bonding surface, a portion of the first substrate 10 and a portion of the first support material are sequentially etched to form the cavity 170 penetrating in a direction approaching the third surface and communicating with the first through hole 130, the remaining first support material constitutes the first support layer 90, the second support material 102 located in the first through hole 130 and the third support material 111 located in the second through hole 140 are removed, and portions of the second support material 102 and the third support material 111 corresponding to the cavity 170, respectively, the remaining second support material 102 constitutes the second support layer 100, and the remaining third support material 111 constitutes the third support layer 110, as shown in fig. 1.

After the step of removing the second substrate 101 to form the second bonding unit, the first diaphragm 401 and the second diaphragm 402 in the first bonding unit and the second bonding unit are bonded, the bonding surfaces are opposite surfaces of the first diaphragm 401 and the second diaphragm 402, and the bonding medium is polycrystalline and polysilicon.

Specifically, the first substrate 10 may be polished or thinned by a conventional semiconductor Chemical Mechanical Polishing (CMP) or thinning process to make the thickness of the first substrate 10 reach a preset design value, and the preset design value includes 200 to 600 μm, and then a portion of the first substrate 10 and a portion of the first support material may be sequentially etched by a conventional semiconductor process method such as double-sided photolithography and deep trench etching, so that the remaining first substrate 10 and the first support material form a cavity 170, the cavity 170 is penetrated with the first through hole 130, the first opening and the second opening, the remaining first support material forms the first support layer 90, and the first support layer 90 is used to support the first back plate 20, so that an isolation is formed between the first back plate 20 and the first substrate 10, and a firm connection is formed between the first back plate 20 and the first diaphragm 401.

Illustratively, a selective wet etching process such as HF or BOE solution or Vapor phase etching (Vapor HF) is used to remove the second support material 102 located in the first through hole 130, and the second support material 102 is etched through the first through hole 130, so that the portions of the second support material 102 corresponding to the cavities 170 respectively form the first voids 150, and the remaining second support material 102 forms the second support layer 100.

Illustratively, a selective wet etching process such as HF or BOE solution or Vapor phase etching (Vapor HF) is used to remove the third support material 111 located in the second through hole 140, and etch the third support material 111 through the second through hole 140, so as to remove the portions of the third support material 111 corresponding to the cavities 170 respectively to form the second voids 160, and the remaining third support material 111 forms the third support layer 110.

The first support layer 90, the second support layer 100 and the third support layer 110 support edges of the first back plate 20, the first diaphragm 401, the second diaphragm 402 and the second back plate 60 to form a stable connection. And, by forming the first and second gaps 150 and 160 corresponding to the cavity 170, the first and second gaps 150 and 160, the first and second through holes 130 and 140, and the vent hole in the through hole diaphragm 40 between the cavities 170 are communicated to form a pressure release channel, so as to maintain the pressure balance of the first and second diaphragms 401 and 402.

From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

Compared with the existing multilayer capacitive MEMS microphone with the double-layer vibrating diaphragm and the double-layer backboard, the manufacturing flow of the existing structure is that the multilayer capacitive MEMS microphone is formed by adopting the manufacturing method of the stacked film layers in the traditional single-layer MEMS microphone, so that the stress control of the MEMS microphone structure is difficult. According to the MEMS microphone, the first vibrating diaphragm in the first bonding unit and the second vibrating diaphragm in the second bonding unit are directly bonded, so that the first bonding unit and the second bonding unit are connected, the first bonding unit and the second bonding unit jointly form the MEMS microphone, and in the MEMS microphone with the structure, as the first bonding unit and the second bonding unit are independent units manufactured by adopting similar process flows, the original complex process is simplified, the problem that stress control of devices in the MEMS microphone structure is difficult due to stacking of film layers is avoided, meanwhile, the mask number in manufacturing is reduced, the process difficulty is greatly reduced, and the large-scale mass production of the MEMS microphone is simpler.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (12)

1. A MEMS microphone, the MEMS microphone comprising:

The first bonding unit comprises a first vibrating diaphragm, a first backboard and a first connecting part, wherein a first through hole is formed in the first backboard, the first connecting part is positioned on the first surface of the first backboard, a first gap is formed between the first vibrating diaphragm and the first backboard and is connected through the first connecting part, and the first gap is communicated with the first through hole;

The second bonding unit comprises a second vibrating diaphragm, a second backboard and a second connecting part, wherein the second backboard is provided with a second through hole, the second connecting part is positioned on the second surface of the second backboard, a second gap is arranged between the second vibrating diaphragm and the second backboard and is connected with the second connecting part, the second gap is communicated with the second through hole,

The first vibrating diaphragm is directly connected with the second vibrating diaphragm in a bonding way.

2. The MEMS microphone of claim 1, wherein the first backplate has a third surface opposite the first surface, the second backplate has a fourth surface opposite the second surface, the MEMS microphone further comprising:

a first passivation layer covering the first surface and the third surface;

And a second passivation layer covering the second surface and the fourth surface.

3. The MEMS microphone of claim 1, wherein the MEMS microphone further comprises:

A first substrate disposed on a side of the first back plate having the third surface, and having a cavity penetrating in a direction approaching the third surface therein, the cavity communicating with the first through hole;

and the third connecting part is connected with the first substrate and the first backboard.

4. The MEMS microphone of claim 3, further comprising:

And each electrode is arranged on one side of the second backboard, which is provided with the fourth surface, and the electrodes are connected with the second backboard.

5. The MEMS microphone according to any one of claims 1-4, wherein the first connection portion and/or the second connection portion comprises a first conductive portion having a first direction of extension away from the first backplate and a second conductive portion having a second direction of extension away from the first backplate, the first direction of extension intersecting the first direction of extension.

6. The manufacturing method of the MEMS microphone is characterized by comprising the following steps of:

Forming a first bonding unit on a first substrate, wherein the first bonding unit comprises a first vibrating diaphragm, a first backboard and a first connecting part, the first backboard is provided with a first through hole, the first connecting part is positioned on the first surface of the first backboard, a first gap is formed between the first vibrating diaphragm and the first backboard and is connected through the first connecting part, and the first gap is communicated with the first through hole;

Providing a second bonding unit, wherein the second bonding unit comprises a second vibrating diaphragm, a second backboard and a second connecting part, the second backboard is provided with a second through hole, the second connecting part is positioned on the second surface of the second backboard, a second gap is formed between the second vibrating diaphragm and the second backboard and is connected through the second connecting part, and the second gap is communicated with the second through hole;

And directly bonding and connecting the first vibrating diaphragm and the second vibrating diaphragm.

7. The method of manufacturing a MEMS microphone according to claim 6, wherein the step of forming the first bonding unit comprises:

forming a first support material on the first substrate to cover the first substrate;

Forming a first sub-passivation layer on the surface of the first support material away from the first substrate;

Forming the first backboard on one side of the first sub passivation layer away from the first substrate, wherein the first backboard is provided with a third surface opposite to the first surface;

Forming a second sub-passivation layer on one side of the first backboard far away from the first sub-passivation layer, wherein the first sub-passivation layer and the second sub-passivation layer jointly form a first passivation layer, the first passivation layer covers the first surface and the third surface, and a first penetrating hole is formed in the first sub-passivation layer, the first backboard and the second sub-passivation layer;

and forming the first connecting part and the first vibrating diaphragm on one side of the second sub-passivation layer far away from the first substrate.

8. The method of manufacturing a MEMS microphone according to claim 7, wherein the step of forming the first connection portion and the first diaphragm comprises:

Depositing a second supporting material on the second sub-passivation layer, so that part of the second supporting material covers the second sub-passivation layer, and the other part of the second supporting material is filled in the first through hole;

Forming a first connection hole sequentially penetrating the second support material and the second sub-passivation layer;

And depositing a first vibrating diaphragm material on one side of the second supporting material far away from the first backboard, so that part of the first vibrating diaphragm material covers the surface of the second supporting material to form the first vibrating diaphragm, and the other part of the first vibrating diaphragm material is filled in the first connecting hole to form the first connecting part.

9. The method of manufacturing a MEMS microphone according to claim 6, wherein the step of forming the second bonding unit comprises:

providing a second substrate, and forming a third sub-passivation layer on the second substrate;

forming a second backboard on one side of the third sub passivation layer away from the second substrate, wherein the second backboard is provided with a fourth surface opposite to the second surface;

Forming a fourth sub-passivation layer on one side of the second backboard far away from the third sub-passivation layer, wherein the third sub-passivation layer and the fourth sub-passivation layer jointly form a second passivation layer, the second passivation layer covers the second surface and the fourth surface, and a penetrating second through hole is formed in the third sub-passivation layer, the second backboard and the fourth sub-passivation layer;

forming the second connecting part and the second vibrating diaphragm on one side of the fourth sub-passivation layer far away from the second substrate;

And removing the second substrate.

10. The method of manufacturing a MEMS microphone according to claim 9, wherein the step of forming the second connection portion and the second diaphragm comprises:

Depositing a third supporting material layer on the fourth sub-passivation layer, so that part of the third supporting material layer covers the fourth sub-passivation layer, and the other part of the third supporting material layer is filled in the second through hole;

Forming a second connection hole sequentially penetrating the third support material and the fourth sub-passivation layer;

and depositing a second vibrating diaphragm material on one side of the third supporting material far away from the second backboard, so that part of the second vibrating diaphragm material covers the surface of the third supporting material to form the second vibrating diaphragm, and the other part of the second vibrating diaphragm material is filled in the second connecting hole to form the second connecting part.

11. The method of manufacturing a MEMS microphone of claim 10, further comprising:

forming a plurality of electrode openings in the third sub-passivation layer through to the second backplate;

An electrode material is deposited in each of the electrode openings to form an electrode, the electrode being connected to the second backplate.

12. The method of manufacturing a MEMS microphone according to any of claims 7-11, wherein the method of manufacturing further comprises:

After the step of directly bonding and connecting the first diaphragm and the second diaphragm, sequentially etching a part of the first substrate and a part of the first support material to form a cavity penetrating in a direction approaching to the third surface and communicating with the first through hole, wherein the rest of the first support material forms a first support layer, the second support material positioned in the first through hole and the third support material positioned in the second through hole are removed, and parts corresponding to the cavity respectively in the second support material and the third support material form a second support layer, and the rest of the second support material forms a third support layer.