JP2002209298A - Manufacturing method for capacitor microphone, capacitor microphone and electronic unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor microphone manufacturing method which is excellent in productivity and by which a desired characteristic (a mechanical characteristic or an acoustic characteristic) is obtained and to provide a capacitor microphone and an electronic unit provided with the capacitor microphone. SOLUTION: The capacitor microphone 1 is provided with a board 2 and the board 2 is provided with a metallic back plate 7 where a plurality of acoustic holes (through-holes) 73 are formed and a diaphragm 3 movable to the back plate 7 so as to form a capacitor. A recessed part 23 is formed in a place corresponding to the diaphragm 3 of the board 2. A semiconductor board is used as the board 2 and the back plate 7 is formed by a plating method. In this case, a wet plating method is favorable and an electrolytic plating method is more favorable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a condenser microphone, a condenser microphone, and an electronic apparatus.

[0002]

2. Description of the Related Art There is known a condenser microphone in which a back plate in which a plurality of through holes called acoustic holes are formed on a silicon substrate, and a diaphragm movable with respect to the back plate to form a condenser. ing.

[0003] For example, Japanese Patent Publication No. Sho 60-500841 discloses a condenser microphone in which a glass back plate is formed on a silicon substrate.

However, in the condenser microphone, since the back plate is formed by processing the glass, the productivity is low and the processing accuracy is low.

In particular, it is not easy to form an acoustic hole in glass, and the process (operation) requires a relatively long time.

Further, since the processing accuracy of the back plate is poor, desired characteristics may not be obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a condenser microphone which is excellent in productivity and can obtain desired characteristics (mechanical characteristics and acoustic characteristics), a condenser microphone and the condenser microphone. To provide an electronic device having the same.

[0008]

This and other objects are achieved by the present invention which is defined below as (1) to (15).

(1) Manufacture of a capacitor microphone in which a metal back plate having at least one through hole formed in a semiconductor substrate and a diaphragm movable with respect to the back plate are provided so as to form a capacitor. A method of manufacturing a condenser microphone, wherein the back plate is formed by a plating method.

(2) A sacrificial layer is formed before the back plate is formed, and after the back plate is formed, the sacrificial layer is removed, so that a space is formed between the back plate and the diaphragm. The method for manufacturing the condenser microphone according to the above (1) to be formed.

(3) Manufacture of a condenser microphone in which a metal back plate having at least one through hole formed in a semiconductor substrate and a diaphragm movable with respect to the back plate are provided to form a capacitor. Forming a film to be the diaphragm on the semiconductor substrate, forming a sacrificial layer, forming the back plate by a plating method so as to cover the sacrificial layer, A condenser microphone comprising: a step of partially removing a portion of a substrate corresponding to the diaphragm; and a step of removing the sacrificial layer to form a space between the back plate and the diaphragm. Manufacturing method.

(4) The method of manufacturing a condenser microphone according to (3), wherein, in the step of forming the space, the sacrificial layer is dissolved and discharged through the through hole.

(5) The method of manufacturing a condenser microphone according to any one of (1) to (4), wherein a predetermined portion other than the through hole is selectively plated to form the back plate.

(6) In the step of forming the back plate, a step of forming a mask on a portion to be the through hole and a portion of the non-plated portion other than the through hole, and a step of plating. The method of manufacturing a condenser microphone according to any one of the above (1) to (4), comprising a step of removing the mask.

(7) The method for manufacturing a condenser microphone according to the above (6), wherein the portion other than the through-hole, which is not plated, is a portion outside the portion to be the back plate.

(8) The method for manufacturing a condenser microphone according to any one of (1) to (7), wherein at least a part of the diaphragm is formed by a part of the semiconductor substrate.

(9) The method for manufacturing a condenser microphone according to any one of the above (1) to (8), wherein the plating method is a wet plating method.

(10) The method of manufacturing a condenser microphone according to any one of (1) to (9), wherein the semiconductor substrate is a single crystal silicon substrate.

(11) A condenser microphone manufactured by the method for manufacturing a condenser microphone according to any one of (1) to (10).

(12) A condenser microphone in which a back plate having at least one through hole formed in a semiconductor substrate and a diaphragm movable with respect to the back plate are provided so as to form a capacitor. A condenser microphone, wherein the back plate is made of metal.

(13) The condenser microphone according to the above (12), wherein the back plate is formed by a plating method.

(14) The condenser microphone according to the above (12) or (13), wherein the semiconductor substrate is a single crystal silicon substrate.

(15) An electronic apparatus comprising the condenser microphone according to any one of (11) to (14).

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a condenser microphone, a condenser microphone and electronic equipment according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the condenser microphone of the present invention. As shown in the figure,
A condenser microphone (condenser type microphone) 1 has a substrate 2. This substrate 2 is a semiconductor substrate.

The substrate 2 has a plurality of acoustic holes (through holes).
A metal back plate 7 on which 73 is formed and a diaphragm 3 movable (displaceable) with respect to the back plate 7 are provided so as to form a capacitor.

A recess 23 is formed in a portion of the substrate 2 corresponding to the diaphragm 3.

A part of the substrate 2, that is, the recess 2
3 is a part (one layer) of the diaphragm 3.

Many microphones 1 are formed on a semiconductor wafer such as a silicon wafer, for example, and are separated from each other by a predetermined means such as dicing to complete the microphone.

The size of the microphone 1 is not particularly limited, but may be, for example, about 2 to 5 mm × 2 to 5 mm, and the thickness may be about 0.2 to 1 mm.

Next, a method of manufacturing the condenser microphone 1 will be described. 2, 3, 4, 5, 6, 7,
FIGS. 8, 9 and 10 are diagrams (longitudinal sectional views) for explaining a method of manufacturing the condenser microphone 1, respectively.
It is.

First, a semiconductor substrate is prepared as the base material 21 of the substrate 2. If the base material 21 is a semiconductor substrate,
Although not particularly limited, a single crystal silicon substrate is preferable.

The thickness of the base material 21 is not particularly limited, but is preferably about 100 to 1000 μm.
More preferably, it is about 200 to 800 μm.

<1> First, as shown in FIG.
, That is, the film 22 is formed on the upper, lower, right, and left sides of the base material 21 in FIG. This film 22
It constitutes a part of the diaphragm 3 and also functions as a mask for etching the base material 21.

The constituent material of the film 22 is, for example, Si
O ₂ , SiN, etc., among them, among these, S
iN is preferred.

When the film 22 is composed of a SiO ₂ film,
The surface (surface layer) of the base material 21 is oxidized (thermally oxidized).

When the film 22 is formed of a SiN film, the surface of the base material 21 is formed by CVD (Chemical Vapor Deposit).
An SiN film is deposited by an ion) method.

The thickness of the film 22 is not particularly limited.
It is preferably about 0.05 to 2 μm, and 0.5 to 1 μm.
More preferably, it is about μm. The base material 21
And the film 22 constitute the substrate 2.

Next, if necessary, predetermined circuits (integrated circuits) such as an amplifier circuit and a booster circuit are formed on the upper side of the substrate 2 in FIG.

<2> Next, as shown in FIG. 3, an electrode 4 is formed on the upper side of the substrate 2 in FIG. The electrode 4 forms a part of the diaphragm 3.

The electrode 4 has conductivity, and its constituent materials include, for example, various metals, polysilicon (polycrystalline silicon) and the like.
Metals are preferred.

When the electrode 4 is formed of a metal film, the metal is not particularly limited, and examples thereof include Cu, Cu-based alloy, Al, Al-based alloy, Au, Pt, W, and W-based alloy. .

When the electrode 4 is made of a polysilicon film, it is preferable to implant a predetermined dopant into the polysilicon film at a high concentration to improve the conductivity of the electrode 4.

As the dopant, for example, B, P, A
s, Al and the like. In addition, as a method for implanting a dopant, for example, ion implantation or the like can be given.

Although the thickness of the electrode 4 is not particularly limited,
It is preferably about 0.05 to 0.5 μm,
More preferably, it is about 0.2 μm.

Next, an insulating film 5 is formed on the upper side of the electrode 4 in FIG. This insulating film 5 constitutes a part of the diaphragm 3.

In the present embodiment, as shown in FIG. 3, the insulating film 5 is formed so as to cover the electrode 4 other than the right end in FIG. The insulating film 5 insulates the electrode 4 and the back plate 7 from each other.

As a constituent material of the insulating film 5, for example, S
iO _2, SiN, and the like. The thickness of the insulating film 5 is not particularly limited, but is preferably about 0.03 to 1 μm, and more preferably about 0.05 to 0.2 μm.

The insulating film 5 may be formed only between the electrode 4 and the end 74 of the back plate 7 (see FIG. 1). In this case, the insulating film 5 does not become a part of the diaphragm 3.

<3> Next, as shown in FIG. 4, a sacrificial layer 6 is formed above the substrate 2 and the insulating film 5 in FIG.

The sacrifice layer 6 is a portion to be finally removed, and in this embodiment, as shown in FIG.
4 is formed so as to cover portions other than the right end in FIG. 4, and also on the substrate 2 near the left end of the insulating film 5 in FIG.

The sacrificial layer 6 is formed in a predetermined pattern by, for example, photolithography.

The constituent material of the sacrifice layer 6 includes, for example, polyimide, various resist materials, SiO _2, etc. Among them, from the viewpoint that the sacrifice layer 6 can be more easily removed. , Polyimide or resist material is preferred.

Although the thickness of the sacrificial layer 6 is not particularly limited,
The thickness of the sacrificial layer 6 at the position of the electrode 4 is preferably about 1 to 6 μm, more preferably about 3 to 5 μm.

<4> Next, a metal back plate 7 is formed by plating so as to cover the sacrificial layer 6.

The method of forming the back plate 7 is not particularly limited as long as it is a plating method. For example, wet plating methods such as electrolytic plating (electroplating) and electroless plating, sputtering, ion plating, vacuum deposition, CVD Examples thereof include dry plating methods (gas phase film forming methods) such as (chemical vapor deposition method), and among these, wet plating methods are preferable, and electrolytic plating methods are more preferable.

By using the wet plating method, particularly the electrolytic plating method, the back plate 7 having a predetermined thickness can be formed easily, quickly and reliably with high precision.

It is preferable that a predetermined portion other than the acoustic hole 73 is selectively plated to form the back plate 7. That is, it is preferable to use the selective plating method.

By using the selective plating method, the number of steps can be reduced as compared with the case where the acoustic hole 73 is formed later by, for example, etching or the like. Therefore, the productivity is high, which is advantageous for mass production.

Hereinafter, a case in which the back plate 7 is formed by typically using an electrolytic plating method and selectively plating only necessary portions will be described.

<4-> First, as shown in FIG. 5, the upper side of the laminate in FIG. 5, that is, the upper side of the substrate 2, the electrode 4, the insulating film 5, and the sacrificial layer 6 in FIG. A conductive film 71 serving as an electrode for electroforming is formed.

The conductive film 71 is made of a metal.
The metal is not particularly limited. For example, Cu, C
u-based alloys, Cr / Au, Cr / Ni, and the like.

The thickness of the conductive film 71 is not particularly limited, but is preferably about 0.05 to 1 μm,
More preferably, it is about 0.2 μm.

<4-> Next, as shown in FIG. 6, a mask 81 for plating (electroforming) the back plate 7 is formed on the upper side of the conductive film 71 in FIG.

The masks 81 are formed in portions of the back plate 7 that are to be a plurality of acoustic holes (through holes) 73.

The mask 81 is provided in the acoustic hole 73.
Other portions that are not plated, that is, portions outside the portion to be the back plate 7 (for example, the left and right sides in FIG. 6) are also formed. This prevents (prevents) the formation of a metal layer 72 described later on unnecessary portions, thereby suppressing the consumption and deterioration of the plating solution (material). In addition, since the metal layer 72 is not formed on unnecessary portions, deformation of the substrate 2 and separation of the metal layer 72 can be more reliably prevented.

The mask 81 is formed in a predetermined pattern by, for example, photolithography.

As a constituent material of the mask 81, for example,
Various resist materials can be used.

<4-> Next, as shown in FIG. 7, a conductive film 71 is formed on the conductive film 71 by electrolytic plating (electroplating).
A metal layer 72 is formed.

The metal constituting the metal layer 72 is not particularly limited, and includes, for example, Cu, Cu-based alloy, Ni, Ni-based alloy, Au and the like.

The thickness of the metal layer 72 is not particularly limited, but is preferably about 2 to 30 μm, and 5 to 20 μm.
m is more preferable.

The compositions of the metal layer 72 and the conductive film 71 may be the same or different.

<4-> Next, as shown in FIG. 8, the mask 81 is removed. The removal of the mask 81 is performed by, for example,
It can be performed by a dry etching method, a wet etching method, or the like.

Next, the conductive film 71 in the portion of each acoustic hole 73 is removed, and each acoustic hole 73 is penetrated.

Thus, a plurality of acoustic holes 73 are formed, and the back plate 7 composed of the metal layer 72 and the conductive film 71 is formed.

The shape of the acoustic hole 73 in plan view (the shape when viewed from above in FIG. 8) is not particularly limited, and may be, for example, a polygon such as a quadrangle, a circle, an ellipse, or the like.

The removal of the conductive film 71 can be performed by, for example, a dry etching method or a wet etching method.

<5> Next, the portion of the substrate 2 corresponding to the diaphragm 3 is partially removed to form the diaphragm 3.

<5-> First, as shown in FIG. 9, a portion of the lower film 22 of the substrate 2 in FIG. 9 corresponding to the diaphragm 3, that is, a portion corresponding to the concave portion 23 shown in FIG. The opening 2 having the shape corresponding to the diaphragm 3 is removed.
4 is formed.

The removal of the film 22 can be performed by, for example, a dry etching method, a wet etching method, or the like.

<5-> Next, as shown in FIG. 10, the portion of the opening 24 (base material 21) of the substrate 2 is removed so that the film 22 is exposed.

As a result, a concave portion 23 is formed in the substrate 2, and the diaphragm 3 composed of the film 22, the electrode 4, and the insulating film 5 is formed above the concave portion 23 in FIG.

The formation of the recess 23 is preferably performed by an etching method. That is, it is preferable to etch the portion of the opening 24 of the substrate 2 until the film 22 is exposed.

Examples of the etching method in this case include a dry etching method and a wet etching method, and particularly, an alkali anisotropic etching method is preferable.

When this step is performed by an alkali anisotropic etching method, the film 22 is hardly etched by etching, and only the base material 21 of the substrate 2 is etched. When the film 22 is exposed, it stops. Therefore, the portion of the opening 24 of the substrate 2 can be easily and reliably removed so that the film 22 is exposed, and the diaphragm 3 having a predetermined thickness can be formed accurately.

The alkaline etching solution when using the alkaline anisotropic etching method includes, for example,
An aqueous solution of TMAH (tetramethylammonium hydroxide) is exemplified.

The recess 23 is formed so that the portion 231 on the back plate 7 side (upper side in FIG. 10) is located inside the end 74 of the back plate 7.
That is, the end 74 of the back plate 7 is positioned above the base material 21 of the substrate 2 in FIG. Thereby, the back plate 7 can be more reliably supported by the substrate 2.

<6> Next, as shown in FIG.
The sacrificial layer 6 is removed through the acoustic holes 73 of the back plate 7 by using a gas or a liquid for removing.

At this time, gas or liquid for removing the sacrifice layer 6 enters through the acoustic hole 73, whereby the sacrifice layer 6 is decomposed or dissolved and discharged.

Thus, a hollow portion (space) 9 communicating with the acoustic hole 73 is formed between the back plate 7 and the diaphragm 3.

For removing the sacrifice layer 6, for example, when the sacrifice layer 6 is made of SiO ₂ , HF (hydrogen fluoride) or the like is used. , O ₂ plasma or the like is used. Thereby, only the sacrificial layer 6 can be selectively removed.

Next, the electrode 4 of the diaphragm 3 and the back plate 7 are electrically connected to a predetermined circuit (not shown) provided on the upper side of the substrate 2 in FIG. 1 by, for example, a lead wire (not shown). . As described above, the condenser microphone 1 shown in FIG. 1 is obtained.

Next, the operation of the condenser microphone 1 will be described. When a sound, that is, a sound wave enters the condenser microphone 1 while the condenser microphone 1 is in an operating state, the diaphragm 3 vibrates due to the sound wave (sound pressure).

When the diaphragm 3 vibrates, the distance (interval) between the diaphragm 3 and the back plate 7 changes according to the magnitude of the amplitude, and the capacitance of the capacitor formed by the diaphragm 3 and the back plate 7 changes. Changes.

This change in capacitance is expressed as an electric signal as
Output from the condenser microphone 1. That is,
The acoustic signal is converted into an electric signal by the condenser microphone 1 and output.

As described above, according to the condenser microphone 1 and the method of manufacturing the same, the back plate 7
Is made of metal and therefore has high rigidity and strength.

Further, the back plate 7 can be easily and accurately formed by plating.

For this reason, the condenser microphone 1
Has excellent characteristics (mechanical characteristics and acoustic characteristics).

The microphone 1 can be formed by a semiconductor manufacturing process (particularly, micromachining). Therefore, it can be easily and precisely machined,
It has high productivity, is advantageous for mass production, and is also advantageous for miniaturization.

Further, the microphone 1 and its peripheral circuits can be formed (integrated) on the same substrate.

The condenser microphone 1 described above can be used by being incorporated in various electronic devices (electronic devices).

Next, an embodiment in which the electronic apparatus of the present invention is applied to a hearing aid will be described.

FIG. 11 is a perspective view showing an embodiment in which the electronic apparatus of the present invention is applied to a hearing aid, that is, an embodiment of a hearing aid provided with the condenser microphone 1 shown in FIG.

As shown in the figure, a hearing aid (electronic device) 1
00 has a casing (exterior member) 110 in which an opening 120 is formed.

In the casing 110, the condenser microphone 1 described above, a speaker (not shown), and a predetermined electric circuit (not shown) electrically connected to the condenser microphone 1 and the speaker are provided, respectively.

The condenser microphone 1 is arranged such that the concave portion 23 of the substrate 2 faces the sound source direction and the concave portion 23, that is, the diaphragm 3 is located at the position of the opening 120.

Next, the operation of the hearing aid 100 will be described. As described above, the sound (sound pressure) from the sound source is converted into an electric signal by the condenser microphone 1.

This electric signal is subjected to signal processing in an electric circuit, input to a speaker, converted again into sound by the speaker, and output.

Thus, the user of the hearing aid 100 can easily and reliably hear the sound from the sound source.

As described above, this hearing aid 100
Has a very good performance because of the built-in condenser microphone 1 described above.

The present invention is not limited to the above-mentioned hearing aids, but also includes, for example, mobile phones (including PHS), video phones,
The present invention can be applied to any electronic device having a microphone, such as a telephone, a voice input device such as a mobile phone, a videophone and a telephone.

As described above, the method for manufacturing the condenser microphone, the condenser microphone and the electronic apparatus of the present invention are described below.
Although the description has been given based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each unit can be replaced with any configuration having the same function.

In the above embodiment, the end portion 74 of the back plate 7 is a spacer for forming a predetermined gap between the back plate 7 and the diaphragm. However, the present invention is not limited to this. For example, the back plate and the spacer may be formed of different members, or the back plate and the spacer may be formed of different constituent materials.

In the present invention, the spacer may be formed of a constituent material other than metal. In addition, as a constituent material of the spacer, for example, polyimide, various resist materials,
SiO _{2 and the} like.

[0115]

As described above, according to the present invention, a back plate can be formed easily and accurately.
Also, since the back plate is made of metal,
High rigidity and strength.

As a result, a condenser microphone having high performance, that is, excellent mechanical and acoustic characteristics can be obtained.

Further, the condenser microphone can be easily manufactured, the productivity is high, and it is advantageous for mass production.
It is also advantageous for miniaturization.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a condenser microphone of the present invention.

FIG. 2 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 3 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 4 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 5 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 6 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 7 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 8 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 9 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 10 is a view (longitudinal sectional view) for explaining a method of manufacturing the condenser microphone shown in FIG. 1;

FIG. 11 is a perspective view showing an embodiment in which the electronic apparatus of the present invention is applied to a hearing aid.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condenser microphone 2 Substrate 21 Base material 22 Film 23 Concave part 231 Part 24 Opening 3 Diaphragm 4 Electrode 5 Insulating film 6 Sacrificial layer 7 Back plate 71 Conductive film 72 Metal layer 73 Acoustic hole 74 End 81 Mask 9 Hollow 100 Hearing aid 110 Casing 120 opening

Claims (15)

[Claims] 1. A method of manufacturing a capacitor microphone comprising: a metal back plate having at least one through hole formed in a semiconductor substrate; and a diaphragm movable with respect to the back plate so as to form a capacitor. A method of manufacturing a condenser microphone, wherein the back plate is formed by a plating method. 2. A space is formed between the back plate and the diaphragm by forming a sacrificial layer before forming the back plate and removing the sacrificial layer after forming the back plate. The method for manufacturing the condenser microphone according to claim 1. 3. A method for manufacturing a condenser microphone comprising: a metal back plate having at least one through hole formed in a semiconductor substrate; and a diaphragm movable with respect to the back plate so as to form a capacitor. A step of forming a film to be the diaphragm on the semiconductor substrate; a step of forming a sacrificial layer; a step of forming the back plate by a plating method so as to cover the sacrificial layer; A step of partially removing a portion corresponding to the diaphragm, and a step of forming a space between the back plate and the diaphragm by removing the sacrificial layer. Production method. 4. The method according to claim 3, wherein, in the step of forming the space, the sacrificial layer is dissolved and discharged through the through hole. 5. The method of manufacturing a condenser microphone according to claim 1, wherein a predetermined portion other than the through hole is selectively plated to form the back plate. 6. The step of forming the back plate includes the steps of: forming a mask on a portion to be the through hole and a portion other than the through hole and not being plated; 5. The method for manufacturing a condenser microphone according to claim 1, further comprising a step of removing a mask. 7. The method of manufacturing a condenser microphone according to claim 6, wherein a portion other than the through-hole and not plated is a portion outside a portion to be the back plate. 8. The method of manufacturing a condenser microphone according to claim 1, wherein at least a part of said diaphragm is formed by a part of said semiconductor substrate. 9. The method according to claim 1, wherein the plating method is a wet plating method. 10. The method of manufacturing a condenser microphone according to claim 1, wherein said semiconductor substrate is a single crystal silicon substrate. 11. A condenser microphone manufactured by the method for manufacturing a condenser microphone according to claim 1. Description: 12. A condenser microphone comprising: a back plate having at least one through hole formed in a semiconductor substrate; and a diaphragm movable with respect to the back plate so as to form a capacitor. A condenser microphone, wherein the plate is made of metal. 13. The condenser microphone according to claim 12, wherein the back plate is formed by a plating method. 14. The condenser microphone according to claim 12, wherein the semiconductor substrate is a single crystal silicon substrate. 15. An electronic apparatus comprising the condenser microphone according to claim 11. Description: