TWI852327B - Microphone and mems acoustic sensor using the same - Google Patents

Abstract

A mems acoustic sensor includes a silicon layer and an insulating layer is arranged above the silicon layer. Three first electrode layers are arranged separately on the insulating layer at intervals with each other. Three second electrode layers are arranged respectively on the three first electrode layers. The three second electrode layers, the three first electrode layers and the insulating layer between the three first electrode layers jointly formed two acoustic flow channels. The acoustic flow channel has a flow direction. Among the three second electrode layers, the two second electrode layers located on both sides are respectively composed of a front section and a back section. The front section forms an expanding first arc along the flow direction. The rear section is continuously extended from the first arc and forms a tapering second arc along the flow direction.

Description

Microphone and its MEMS acoustic sensor

The present invention is mainly an acoustic device, in particular a microphone and a micro-electromechanical system acoustic sensor used in the field of acoustics.

According to the market, there are many types of microphones, such as dynamic, capacitive, aluminum ribbon and carbon. In addition, in mobile devices such as mobile phones, the most common are electromechanical (ECM) capacitive microphones and micro-electromechanical systems (MEMS) microphones. Among them, MEMS uses semiconductor processes to manufacture tiny mechanical components. It uses semiconductor technologies such as deposition and selective etching of material layers to complete the microphone's acoustic sensor.

It is known that the main factor affecting the sensitivity of the acoustic sensor of the microphone is the thickness of the electrode layer and the insulating layer used to make the acoustic sensor. Due to excessive etching during the etching stage, the electrode layer and the insulating layer will be corroded together, or the upper and lower electrodes will be adsorbed together, which will affect the yield of the acoustic sensor and reduce the sensitivity of the acoustic sensor.

In view of this, it is necessary to provide a microphone and its MEMS acoustic sensor to solve the above problems.

The purpose of the present invention is to provide a micro-electromechanical system acoustic sensor that can increase the amplitude of electrode vibration caused by a sound source.

The second object of the present invention is to provide a microphone having the above-mentioned MEMS acoustic sensor.

To achieve the above-mentioned purpose, the present invention provides a micro-electromechanical system acoustic sensor, comprising: a silicon base layer; an insulating layer, connected and arranged on the silicon base layer; three first electrode layers, connected and arranged on the insulating layer at intervals, and extending along a row direction of the insulating layer; three second electrode layers, connected and arranged on the three first electrode layers respectively, among which the second electrode layers located on both sides respectively form at least one supporting member, and are connected and arranged on the corresponding first electrode layer through the at least one supporting member, and the three second electrode layers, the three first electrode layers and the first electrode layers located between the three first electrode layers are connected and arranged on the first electrode layer respectively. The insulating layer forms two sound flow channels together. The sound flow channel has an inlet end and an outlet end, and forms a sound flow direction extending along the row direction from the inlet end to the outlet end. Among the three second electrode layers, the second electrode layers located on both sides are respectively composed of a front section closer to the inlet end and a rear section. The front section is opposite to the outer surface of the second electrode layer located in the middle, and forms a first arc surface that gradually expands along the sound flow direction. The rear section is opposite to the outer surface of the second electrode layer located in the middle, and continuously extends from the surface of the first arc surface, and forms a second arc surface that gradually contracts along the sound flow direction.

The present invention also provides a micro-electromechanical system acoustic sensor, comprising: a silicon base layer; an insulating layer connected to and disposed on the silicon base layer; three first electrode layers connected to and disposed on the insulating layer at intervals and extending along a row direction of the insulating layer; three second electrode layers connected to and disposed on the three first electrode layers respectively, wherein the second electrode layers located on both sides of the three second electrode layers each form at least one supporting member, and are connected to and disposed on the corresponding first electrode layer through the at least one supporting member, and the three second electrode layers, the three first electrode layers and the insulating layers located between the three first electrode layers are connected to and disposed on the first electrode layer. The layers together form two acoustic flow channels, the acoustic flow channels have an inlet end and an outlet end, and form an acoustic flow direction extending along the row direction from the inlet end to the outlet end. Among the three second electrode layers, the second electrode layers located on both sides are respectively composed of a front section closer to the inlet end and a rear section. The front section faces the inner surface of the second electrode layer located in the middle and forms a first arc surface that gradually expands along the acoustic flow direction. The rear section faces the inner surface of the second electrode layer located in the middle and continuously extends from the surface of the first arc surface and forms a second arc surface that gradually contracts along the acoustic flow direction.

In some embodiments, the first electrode layer connected to the second electrode layers located on both sides is composed of at least one electrode member, the number of electrode members of the first electrode layer is equal to the number of supporting members of the connected second electrode layer, and the cross-sectional area of the electrode member is not less than the cross-sectional area of the supporting member.

In some embodiments, the number of supporting members of the second electrode layer located on both sides is two respectively, and a through hole is formed between the two supporting members.

In some embodiments, the junction of the front section and the rear section is located at the center of the support member closer to the inlet end of the two support members.

In some embodiments, the silicon base layer is selected from silicon, silicon germanium, silicon carbide, glass substrate or III-V compound semiconductor.

In some embodiments, the insulating layer is selected from silicon oxide, silicon nitride, silicon oxynitride, a dielectric material with a dielectric constant of 2.5 to 3.9, or a dielectric material with a dielectric constant less than 2.5.

In some embodiments, the three first electrode layers and the three second electrode layers are all made of conductive materials.

In some embodiments, the conductive material is a metal, a metal compound, or an ion-doped semiconductor material.

In some embodiments, the second electrode layer located in the middle has a first end and a second end disposed opposite to each other, the first end is closer to the inlet end and forms a curved surface convex toward the inlet end, and the second end is closer to the outlet end and forms a curved surface convex toward the outlet end.

In some embodiments, the second electrode layer located in the middle has a first end and a second end disposed opposite to each other, the second end is closer to the outlet end, and forms a water drop shape toward the inlet end.

To achieve the above-mentioned purpose, the present invention provides a microphone, comprising: a housing having a first stacking area, a second stacking area and a third stacking area, the second stacking area being located between the first stacking area and the third stacking area, and the first stacking area, the second stacking area and the third stacking area together forming a containing space, the housing having a sound hole; the above-mentioned micro-electromechanical system acoustic sensor being located in the containing space, and the inlet end of the sound flow channel and the sound hole being arranged face to face; and an integrated circuit chip being located in the containing space and electrically connected to the micro-electromechanical system acoustic sensor.

In some embodiments, the housing is provided with a through hole penetrating the inner and outer surfaces of the second stacking area toward the accommodating space to form the sound hole.

In some embodiments, the housing is provided with a through hole penetrating the inner and outer surfaces of the third stacking area toward the accommodating space to form the sound hole.

In some embodiments, the housing further has a row of sound holes, which are arranged on the housing on the opposite side of the sound hole.

The microphone and the micro-electromechanical system acoustic sensor of the present invention have the following characteristics: by designing the front section of the second electrode layer located on both sides to be a gradually expanding arc surface and the rear section thereof to be a gradually contracting arc surface, when the external sound source passes through, part of it passes through the two sound flow channels, and the other part flows along the outer surface of the second electrode layer located on both sides, and finally all converges to the tail end of the second electrode layer, and in the process of the external sound source flowing, the second electrode layers located on both sides shake relative to the second electrode layer located in the middle, causing the distance to change, thereby generating about twice the capacitance value. Thus, the microphone and its MEMS acoustic sensor of the present invention have the effects of improving sensitivity and having high directivity.

[The present invention]

1: Silicon base layer

2: Insulation layer

3: First electrode layer

3a: Electrode parts

4: Second electrode layer

4a: Front section

4b: Later stage

41: Support parts

5: Shell

5a: First stacking area

5b: Second stacking area

5c: The third stacking area

51: Sound hole

52: Sound hole

6: Integrated circuit chip

C: Acoustic flow channel

D: Sound flow direction

E1: Entry end

E2: Exit port

H: Perforation

S: Storage space

X: row direction

Y: column direction

[Figure 1] is a top view of the MEMS acoustic sensor of the first embodiment of the present invention; [Figure 2] is a side view of the MEMS acoustic sensor of the first embodiment of the present invention; [Figure 3] is a top view of the MEMS acoustic sensor of the second embodiment of the present invention; [Figure 4] is a top view of the MEMS acoustic sensor of the third embodiment of the present invention; [Figure 5] is a side view of the MEMS acoustic sensor of the third embodiment of the present invention; [Figure 6] is a top view of the MEMS acoustic sensor of the fourth embodiment of the present invention; [Figure 7] is a side view of the microphone of the present invention; [Figure 8] is a state diagram of the flow direction of sound when the microphone of the present invention is in use.

The embodiments of the present invention are described in detail with the help of the drawings. The attached drawings are mainly simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner. Therefore, only the components related to the present invention are marked in the drawings, and the components shown are not drawn in the number, shape, size ratio, etc. during implementation. The actual specifications and dimensions during implementation are actually a selective design, and the layout of the components may be more complicated.

The following descriptions of the embodiments refer to the attached drawings to illustrate specific embodiments according to which the present invention can be implemented. The directional terms mentioned in the present invention, such as "upper", "lower", "front", "back", etc., are only with reference to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and understand the present application, rather than to limit the present application. In addition, in the specification, unless explicitly described to the contrary, the word "comprising" will be understood to mean including the elements described, but not excluding any other elements.

Please refer to Figures 1 and 2, which are respectively a top view and a side view of the first embodiment of the micro-electromechanical system acoustic sensor of the present invention, which comprises: a silicon base layer 1, an insulating layer 2, three first electrode layers 3 and three second electrode layers 4. The insulating layer 2 is disposed on the silicon base layer 1, the three first electrode layers 3 are disposed on the insulating layer 2, and the three second electrode layers 4 are disposed on the three first electrode layers 3 respectively.

In this embodiment, the silicon base layer 1 can be made of materials such as silicon (Si), silicon germanium (SiGe), silicon carbide (SiC), glass substrate or III-V compound semiconductors (such as gallium nitride (GaN), gallium arsenide (GaAs)).

The insulating layer 2 is connected and arranged on the silicon base layer 1. In this embodiment, the insulating layer 2 can be made of materials selected from silicon oxide, silicon nitride, silicon oxynitride or dielectric materials. The dielectric material can be a low dielectric constant material (dielectric constant falls between 2.5 and 3.9) or an ultra-low dielectric constant material (dielectric constant is less than 2.5). It is worth noting that the number of the insulating layer 2 can also be multiple, and they are stacked layer by layer on the silicon base layer 1, which belongs to the common knowledge in the relevant field to which the present invention belongs.

In this embodiment, the three first electrode layers 3 can be made of conductive materials such as metal, metal compound or ion-doped semiconductor material. The three first electrode layers 3 are connected and arranged on the insulating layer 2 at intervals, and extend along a row direction Y of the insulating layer 2.

In this embodiment, the three second electrode layers 4 can also be made of conductive materials such as metal, metal compound or ion-doped semiconductor material. The three second electrode layers 4 are respectively connected and arranged on the three first electrode layers 3. Specifically, among the three second electrode layers 4, the second electrode layers 4 located on both sides each form at least one supporting member 41, and are connected and arranged on the corresponding first electrode layer 3 through the at least one supporting member 41. On the other hand, in the best embodiment of the present invention, the polarity of the second electrode layers 4 located on both sides is opposite to the polarity of the second electrode layer 4 located in the middle, that is, the polarity of the three second electrode layers 4 can be positive, negative, positive, or negative, positive, negative in sequence, which can be understood by those with ordinary knowledge in the relevant fields of the present invention.

In the present invention, the number of the supporting members 41 of the second electrode layer 4 located on both sides is two as an implementation mode for explanation, and a through hole H is formed between the two supporting members 41, but it is not limited to this. In this way, when the external sound source passes through, the second electrode layer 4 located on both sides can easily shake along the row direction X of the insulating layer 2 to change the distance between each of the second electrode layers 4 located on both sides and the second electrode layer 4 located in the middle, so that the change of the capacitance value is more obvious, which has the effect of further improving the sensitivity of the sensor.

The three second electrode layers 4, the three first electrode layers 3 and the insulating layer 2 between the three first electrode layers 3 together form two acoustic flow channels C. The acoustic flow channel C has an inlet end E1 and an outlet end E2. The acoustic flow channel C forms an acoustic flow direction D extending along the row direction Y from the inlet end E1 to the outlet end E2.

In this embodiment, the two sound flow channels C are independent of each other; in other embodiments, under the premise of not affecting the stability of the second electrode layer 4 located in the middle, that is, when the external sound source passes through the two sound flow channels C, the second electrode layer 4 located in the middle is kept as fixed as possible, then the second electrode layer 4 located in the middle can be opened with at least one through hole to connect the two sound flow channels C.

Furthermore, among the three second electrode layers 4, the second electrode layers 4 located on both sides are respectively composed of a front section 4a closer to the inlet end E1 and a rear section 4b. The front section 4a is opposite to the outer surface of the second electrode layer 4 located in the middle, and forms a first arc surface that gradually expands along the sound flow direction D. The rear section 4b is opposite to the outer surface of the second electrode layer 4 located in the middle, and extends continuously from the surface of the first arc surface, and forms a second arc surface that gradually contracts along the sound flow direction D. On the other hand, the front section 4a and the rear section 4b each face the inner surface of the second electrode layer 4 located in the middle, and can form a plane or a curved surface, but are not limited thereto.

It is worth noting that when the number of the supporting members 41 of the second electrode layer 4 on both sides is two, the junction of the front section 4a and the rear section 4b is the center position of the supporting member 41 located closer to the inlet end E1 among the two supporting members 41.

Preferably, the second electrode layer 4 located in the middle has a first end and a second end arranged opposite to each other, wherein the first end is closer to the inlet end E1 and forms a curved surface convex toward the inlet end E1. The second end is closer to the outlet end E2 and forms a curved surface convex toward the outlet end E2. In this way, the smoothness of the sound source passing through can be improved. In other embodiments, the second end closer to the outlet end E2 can also form a water drop shape toward the inlet end E1.

Please refer to Figure 3, which is a top view of the second embodiment of the micro-electromechanical system acoustic sensor of the present invention. Compared with the first embodiment of the present invention, the front section 4a faces the inner surface of the second electrode layer 4 located in the middle, and forms a first arc surface that gradually expands along the acoustic flow direction D. The rear section 4b faces the inner surface of the second electrode layer 4 located in the middle, extends continuously from the surface of the first arc surface, and forms a second arc surface that gradually contracts along the acoustic flow direction D. On the other hand, the front section 4a and the rear section 4b each face away from the outer surface of the second electrode layer 4 located in the middle, and can form a plane or a curved surface, but are not limited thereto.

Please refer to Figures 4 and 5, which are respectively the top view and the side view of the third embodiment of the micro-electromechanical system acoustic sensor of the present invention. Compared with the first embodiment of the present invention, the first electrode layer 3 connected to the second electrode layer 4 located on both sides is composed of at least one electrode member 3a. The number of electrode members 3a of the first electrode layer 3 is equal to the number of supporting members 41 of the connected second electrode layer 4, and the cross-sectional area of the electrode member 3a is not less than the cross-sectional area of the supporting member 41. In the present invention, the total number of the electrode members 3a is four as an embodiment, but it is not limited to this.

Please refer to Figure 6, which is a top view of the fourth embodiment of the micro-electromechanical system acoustic sensor of the present invention. Compared with the third embodiment of the present invention, the front section 4a faces the inner surface of the second electrode layer 4 located in the middle, and forms a first arc surface that gradually expands along the acoustic flow direction D. The rear section 4b faces the inner surface of the second electrode layer 4 located in the middle, extends continuously from the surface of the first arc surface, and forms a second arc surface that gradually contracts along the acoustic flow direction D. On the other hand, the front section 4a and the rear section 4b each face away from the outer surface of the second electrode layer 4 located in the middle, and can form a plane or a curved surface, but are not limited thereto.

Please refer to Figure 7, which is a side view of a preferred embodiment of the microphone of the present invention, which includes: a housing 5, a micro-electromechanical system acoustic sensor of any of the above embodiments, and an integrated circuit chip 6, wherein the micro-electromechanical system acoustic sensor and the integrated circuit chip 6 are respectively disposed inside the housing 5.

The housing 5 has a first stacking area 5a, a second stacking area 5b and a third stacking area 5c, and the second stacking area 5b is located between the first stacking area 5a and the third stacking area 5c. The first stacking area 5a, the second stacking area 5b and the third stacking area 5c together form a containing space S. In this embodiment, the first stacking area 5a can be made of conductive material or a printed circuit board, the second stacking area 5b and the third stacking area 5c can be made of various plastics, metals, ceramics, bakelite, glass fiber or ceramic materials, and the second stacking area 5b and the third stacking area 5c can be separated from each other or integrally formed.

Furthermore, the housing 5 has a sound hole 51 for an external sound source to enter the accommodation space S. In this embodiment, the housing 5 is provided with a through hole penetrating the inner and outer surfaces of the second stacking area 5b toward the accommodation space S to form the sound hole 51. Thus, when the MEMS acoustic sensor is arranged, it is arranged on the first stacking area 5a, and the inlet end E1 of the sound flow channel C is arranged face to face with the sound hole 51, so that the external sound source enters the sound flow channel C through the sound hole 51.

The housing 5 may also have a row of sound holes 52 for discharging the sound source inside the housing 5. Preferably, the row of sound holes 52 is arranged on the housing on the opposite side of the sound hole 51. In this way, the sound source will not generate an echo in the housing 5, which has the effect of avoiding affecting the performance of the microphone.

In other embodiments, the housing 5 may be provided with a through hole penetrating the inner and outer surfaces of the third stacking area 5c toward the accommodating space S to form the sound hole 51, and the sound hole 52 may be further provided on the first stacking area 5a on the opposite side of the sound hole 51.

Please refer to FIG8 , which is a state diagram of the sound flow direction when the microphone of the present invention is in use. Specifically, when the microphone is in use, the external sound source enters the accommodating space S through the sound hole 51, a part of the external sound source passes through the two sound flow channels C, and the other part of the external sound source is transmitted along the outer surface of the second electrode layer 4 located on both sides, respectively, in the direction away from the sound hole 51, and finally all converge to the tail end of the second electrode layer 4 (the part of the rear section 4b farthest from the front section 4a). Thus, the outer surfaces of the second electrode layers 4 located on both sides have a faster air flow speed and a smaller pressure than the inner surface thereof, so that the second electrode layers 4 located on both sides shake relative to the second electrode layer 4 located in the middle, causing the distance to change, thereby generating about twice the capacitance value (compared to the capacitance value generated when there is no second electrode layer located in the middle). In this way, the MEMS acoustic sensor of the present invention has the effects of improving the sensitivity of the sensor and having high directivity.

As mentioned above, the microphone and the micro-electromechanical system acoustic sensor of the present invention can be designed to have the front section of the second electrode layer located on both sides as a gradually expanding arc surface and the rear section as a gradually contracting arc surface, so that when the external sound source passes through, part of it passes through the two sound flow channels, and the other part flows along the outer surface of the second electrode layer located on both sides, and finally all converges to the tail end of the second electrode layer. In the process of the flow of the external sound source, the second electrode layers located on both sides are shaken relative to the second electrode layer located in the middle, causing the distance to change, thereby generating about twice the capacitance value. Thus, the microphone and its MEMS acoustic sensor of the present invention have the effects of improving sensitivity and having high directivity.

The above disclosed implementation forms are only exemplary of the principles, features and effects of the present invention, and are not intended to limit the scope of implementation of the present invention. Anyone familiar with this technology can modify and change the above implementation forms without violating the spirit and scope of the present invention. Any equivalent changes and modifications completed by using the content disclosed in the present invention should still be covered by the scope of the patent application below.

2: Insulation layer

3: First electrode layer

4: Second electrode layer

4a: Front section

4b: Later stage

C: Acoustic flow channel

D: Sound flow direction

E1: Entry end

E2: Exit port

X: row direction

Y: column direction

Claims (15)

A micro-electromechanical system acoustic sensor comprises: a silicon base layer; an insulating layer connected to and disposed on the silicon base layer; three first electrode layers connected to and disposed on the insulating layer at intervals and extending along a row direction of the insulating layer; three second electrode layers connected to and disposed on the three first electrode layers respectively, wherein the second electrode layers located on both sides of the three second electrode layers each form at least one supporting member and are connected to and disposed on the corresponding first electrode layer through the at least one supporting member, and the three second electrode layers, the three first electrode layers and the insulating layer located between the three first electrode layers are connected to and disposed on the first electrode layer respectively. Two sound flow channels are formed, the sound flow channels have an inlet end and an outlet end, and form a sound flow direction extending along the row direction from the inlet end to the outlet end. Among the three second electrode layers, the second electrode layers located on both sides are respectively composed of a front section closer to the inlet end and a rear section. The front section is opposite to the outer surface of the second electrode layer located in the middle, and forms a first arc surface that expands gradually along the sound flow direction. The rear section is opposite to the outer surface of the second electrode layer located in the middle, and continuously extends from the surface of the first arc surface, and forms a second arc surface that contracts gradually along the sound flow direction. A micro-electromechanical system acoustic sensor comprises: a silicon base layer; an insulating layer connected and arranged on the silicon base layer; three first electrode layers connected and arranged on the insulating layer at intervals and extending along a row direction of the insulating layer; three second electrode layers connected and arranged on the three first electrode layers respectively, wherein the second electrode layers located on both sides of the three second electrode layers each form at least one supporting member and are connected and arranged on the corresponding first electrode layer through the at least one supporting member, and the three second electrode layers, the three first electrode layers and the insulating layer located between the three first electrode layers are connected and arranged on the first electrode layer respectively. Two sound flow channels are formed, the sound flow channels have an inlet end and an outlet end, and form a sound flow direction extending along the row direction from the inlet end to the outlet end. Among the three second electrode layers, the second electrode layers located on both sides are respectively composed of a front section closer to the inlet end and a rear section. The front section faces the inner surface of the second electrode layer located in the middle and forms a first arc surface that expands gradually along the sound flow direction. The rear section faces the inner surface of the second electrode layer located in the middle and continuously extends from the surface of the first arc surface, and forms a second arc surface that contracts gradually along the sound flow direction. A micro-electromechanical system acoustic sensor as described in claim 1 or 2, wherein the first electrode layer connected to the second electrode layers located on both sides is composed of at least one electrode member, the number of electrode members of the first electrode layer is equal to the number of supporting members of the connected second electrode layer, and the cross-sectional area of the electrode member is not less than the cross-sectional area of the supporting member. A micro-electromechanical system acoustic sensor as described in claim 1 or 2, wherein the number of supporting members of the second electrode layer located on both sides is two respectively, and a through hole is formed between the two supporting members. The micro-electromechanical system acoustic sensor as described in claim 4, wherein the junction of the front section and the rear section is located at the center of the support member closer to the inlet end among the two support members. A micro-electromechanical system acoustic sensor as described in claim 1 or 2, wherein the silicon base layer is selected from silicon, silicon germanium, silicon carbide, glass substrate or III-V compound semiconductor. A micro-electromechanical system acoustic sensor as described in claim 1 or 2, wherein the insulating layer is made of silicon oxide, silicon nitride, silicon oxynitride, a dielectric material with a dielectric constant between 2.5 and 3.9, or a dielectric material with a dielectric constant less than 2.5. A micro-electromechanical system acoustic sensor as described in claim 1 or 2, wherein the three first electrode layers and the three second electrode layers are all made of conductive materials. A micro-electromechanical system acoustic sensor as described in claim 8, wherein the conductive material is a metal, a metal compound or an ion-doped semiconductor material. A micro-electromechanical system acoustic sensor as described in claim 1 or 2, wherein the second electrode layer located in the middle has a first end and a second end arranged opposite to each other, the first end is closer to the inlet end and forms a curved surface convex toward the inlet end, and the second end is closer to the outlet end and forms a curved surface convex toward the outlet end. A micro-electromechanical system acoustic sensor as described in claim 1 or 2, wherein the second electrode layer located in the middle has a first end and a second end arranged opposite to each other, the second end is closer to the outlet end and forms a water drop shape toward the inlet end. A microphone comprises: a housing having a first stacking area, a second stacking area and a third stacking area, the second stacking area being located between the first stacking area and the third stacking area, and the first stacking area, the second stacking area and the third stacking area together forming a housing space, the housing having a sound hole; a micro-electromechanical system acoustic sensor as described in any one of claims 1 to 11, located in the housing space, and the inlet end of the sound flow channel is arranged face to face with the sound hole; and an integrated circuit chip, located in the housing space and electrically connected to the micro-electromechanical system acoustic sensor. A microphone as described in claim 12, wherein the housing is provided with a through hole penetrating the inner and outer surfaces of the second stacking area toward the accommodation space to form the sound hole. A microphone as described in claim 12, wherein the housing is provided with a through hole penetrating the inner and outer surfaces of the third stacking area toward the accommodation space to form the sound hole. A microphone as described in claim 12, wherein the housing further has a row of sound holes, and the row of sound holes is arranged on the housing on the opposite side of the sound hole.

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