KR101118627B1 - Mems microphone and manufacturing method the same - Google Patents

Abstract

PURPOSE: An MEMS(Micro Electro Mechanical System) microphone and a manufacturing method thereof are provided to obtain a thickness of a solder part for stable bonding by forming a solder settling part on a membrane part or a back plate part. CONSTITUTION: A first electrode and a first wet layer is formed on a top portion of a first nitride film which is formed in one side of a first silicon substrate(S11). A first solder part is formed on the top portion of the first wet layer(S12). The other side of the first silicon substrate is etched(S13). A membrane part is manufactured(S10). A back plate is formed by etching one side of a second silicon substrate having a second nitride film(S21). A solder settling part is formed by etching the other side of the second silicon substrate(S22). A second electrode and a second wet layer are formed on the top portion of the solder settling part(S23). An acoustic hole is formed on a back plate(S24). A back plate part is manufactured(S20). The membrane part and the back plate part are connected by welding the first solder part and the second solder part(S30).

Description

MEMS microphone and manufacturing method {MEMS MICROPHONE AND MANUFACTURING METHOD THE SAME}

The present invention relates to a microphone and a manufacturing method, and more particularly to a MEMS microphone and a manufacturing method.

Microphones are used in various areas, including acoustics, and are classified into electrokinetic, piezoelectric, piezoresistive, capacitive, and contact methods depending on the driving method.

In particular, in the case of the capacitive type which consists of a charging plate vibrating by sound pressure and an opposite fixed electrode, and converts sound into an electrical signal according to the change in capacitance, the acoustic device has a relatively simple structure, high signal-to-noise ratio, and excellent frequency characteristics. It is widely used in precision measurement equipment.

On the other hand, as the demand for ultra-small microphones is expanding due to the recent miniaturization of electronic devices and the development of personal portable multimedia devices, technologies for simplifying processes and improving yield for low-cost and high-efficiency microphones are required.

Embodiments of the present invention are to provide a MEMS microphone and a manufacturing method for improving the acoustic performance by reducing the air gap at the same time to secure the thickness of the solder portion for stable bonding.

According to an aspect of the invention, the step of forming a first electrode and a first wet layer on the first nitride film formed on one surface of the first silicon substrate on which both the oxide film and the first nitride film sequentially deposited; Forming a first solder portion on the first wet layer; And etching the other surface of the first silicon substrate to manufacture a membrane portion. In parallel with the first step, forming a back plate by etching one surface of a second silicon substrate having a second nitride film deposited on both surfaces thereof; Etching the other surface of the second silicon substrate to form a solder seat; Forming a thermal oxide film on the etched regions of both surfaces of the second silicon substrate, and forming a second electrode and a second wet layer on the solder seat; And forming a second solder part on the second wetted layer, and forming a sound hole in the back plate. And a third step of joining the first solder part and the second solder part to connect the membrane part and the back plate part.

According to another aspect of the invention, the step of etching the one surface of the first silicon substrate in which the oxide film and the first nitride film is sequentially deposited on both sides to form a solder seat; Forming a first thermal oxide film on the solder seat and forming a first electrode and a first wet layer on the first thermal oxide film; And forming a first solder part on the first wetted layer, and etching the other surface of the first silicon substrate. In parallel with the first step, forming a back plate by etching one surface of a second silicon substrate having a second nitride film deposited on both surfaces thereof; Forming a second thermal oxide film on the etched region and forming a second electrode and a second wet layer on both sides of the second silicon substrate; And forming a second solder part on the second wetted layer, and forming a sound hole in the back plate. And a third step of joining the first solder part and the second solder part to connect the membrane part and the back plate part.

The first solder part may be Au solder, the second solder part may be Sn solder, and the connection of the first solder part and the second solder part may be performed at a eutectic melting point temperature of Au—Sn.

The solder seating portion may be etched such that a plane on which the first solder portion is disposed and a first inclined surface inclined from the plane to an upper portion of the first silicon substrate are formed, and the other surface of the second silicon substrate is formed on the second surface. The solder may be etched to form a plane on which the solder part is disposed and a second inclined surface that is inclined to correspond to the first inclined surface.

In this case, the third step may be characterized in that the first inclined surface of the membrane portion and the second inclined surface of the back plate portion) to be aligned and bonded to each other.

In addition, the first inclined surface and the second inclined surface may be characterized in that the sealing area.

According to another aspect of the present invention, in the MEMS microphone comprising a membrane portion vibrating according to the external sound pressure, a back plate portion coupled to the membrane portion and a solder portion for bonding the membrane portion and the back plate portion, the bag The upper part of the plate portion may be provided with a MEMS microphone, characterized in that the solder seat portion is formed is recessed seated.

On the other hand, in the MEMS microphone including a membrane portion vibrating according to an external sound pressure, a back plate portion coupled to the membrane portion and a solder portion for joining the membrane portion and the back plate portion, wherein the solder portion in the lower portion of the membrane portion MEMS microphones can be provided, characterized in that the solder seat is formed to be set and seated.

At this time, the solder seating portion, the plane in which the solder portion is disposed; And a first inclined surface inclined to the upper portion of the membrane in the plane, and the back plate portion may include a second inclined surface inclined to correspond to the first inclined surface.

Embodiments of the present invention can improve the acoustic performance of the microphone by reducing the air gap while ensuring the thickness of the solder portion for stable bonding by forming a solder seating portion in the membrane portion or the back plate.

In addition, by forming the inclined surfaces corresponding to each other and aligned and bonded to the membrane portion and the back plate portion, it is possible to accurately and simply align and bond the membrane portion and the back plate portion without using a separate aligner.

1 is a flow chart of a method for manufacturing a MEMS microphone according to an embodiment of the present invention.
2A is a cross-sectional view illustrating a manufacturing procedure of a membrane unit according to the MEMS microphone manufacturing method of FIG. 1 according to processes.
FIG. 2B is a cross-sectional view illustrating a manufacturing procedure of the back plate unit according to the MEMS microphone manufacturing method of FIG. 1 according to processes. FIG.
3 is a cross-sectional view of a MEMS microphone manufactured according to the MEMS microphone manufacturing method of FIG. 1.
4 is a flowchart illustrating a method of manufacturing a MEMS microphone according to another embodiment of the present invention.
5A is a cross-sectional view illustrating a manufacturing procedure of a membrane unit according to the MEMS microphone manufacturing method of FIG. 4 according to processes.
5B is a cross-sectional view illustrating a manufacturing process of the back plate unit according to the MEMS microphone manufacturing method of FIG. 4 according to processes.
6 is a cross-sectional view of a MEMS microphone manufactured according to the MEMS microphone manufacturing method of FIG. 4.
7 is a cross-sectional view showing a modification of the MEMS microphone manufactured according to the MEMS microphone manufacturing method of FIG. 4.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart of a method of manufacturing a MEMS microphone 100 according to an embodiment of the present invention.

Referring to Figure 1, MEMS microphone manufacturing method (S) is performed in parallel with the first step (S10) and the first step (S10) to manufacture the membrane portion 110 to manufacture the back plate portion 120 A second step (S20) and the third step (S30) for connecting the membrane portion 110 and the back plate portion 120. Hereinafter, each step will be described in detail.

1. The first step

2A is a cross-sectional view illustrating a manufacturing procedure of the membrane part 110 according to the MEMS microphone manufacturing method S of FIG. 1 according to processes.

Referring to FIG. 2A, an oxide film 112 is deposited on both surfaces of the first silicon substrate 111, and a first nitride film 113 is sequentially deposited on the oxide film 112.

The oxide films 112 and SiO ₂ function as a shielding material for dry etching, and may be deposited using, for example, low pressure chemical vapor deposition (LPCVD). The thickness of the oxide film 112 may be about 500 nm.

The first nitride film 113 functions as a vibration film and may be deposited to a thickness of about 1 μm. Meanwhile, it is possible to use a low stress nitride film (low stress SiN _x ) as the first nitride film 113. In this case, there is an effect of improving the flexibility of the vibration membrane. On the other hand, it is also possible to use the silicon substrate on which the oxide film 112 and the first nitride film 113 are deposited as the first silicon substrate 111.

Subsequently, a first electrode 114 and a first wetting layer 114a for eutectic point bonding, which will be described later, are formed on one of the first nitride films 113 deposited on both surfaces of the first silicon substrate 111. The first electrode 114 can be formed, for example, by depositing a thin film of Ti / Au (2000 Å / 1000 Å) (above S11). On the other hand, the first wet layer 114a can be formed by depositing any one of Au, Ni, and Cr.

Next, the first solder portion 115 is formed on the first wetting layer 114a. The first solder part 115 serves to connect the membrane part 110 and the back plate part 120 to each other. On the other hand, the connection may be performed by eutectic bonding (Eutectic Bonding). In this case, the first solder portion 115 uses Au solder, and the second solder portion 127, which will be described later, can be joined to the eutectic point using the eutectic point of the Au-Sn alloy by using Sn solder (above). S12).

Next, the other surface of the first silicon substrate 111 is etched to manufacture the membrane part 110. The etching may be anisotropic etching using a Deep Reactive Ion Etch (DRIE) method (S13).

2. Second Step

FIG. 2B is a cross-sectional view illustrating a manufacturing procedure of the back plate unit 120 according to the process of manufacturing the MEMS microphone S of FIG. 1. Referring to FIG. 2B, the second step S20 is performed in parallel with the first step S10. That is, the first step S10 and the second step S20 are not in order.

In the second step S20, first, second nitride layers SiN _{x 3} N ₄ and 122 are deposited on both surfaces of the second silicon substrate 121. The second nitride film 122 functions as a wet etch shielding material, and may be deposited to a thickness of about 1 μm using, for example, low pressure chemical vapor deposition (LPCVD). On the other hand, it is also possible to use the silicon substrate on which the second nitride film 122 is deposited as the second silicon substrate 121.

Thereafter, one surface of the second silicon substrate 121 is etched to form a back plate 123. For example, it is possible to wet-etch one surface of the second silicon substrate 121 to form the thickness of the back plate 123 to be within 300 μm (S21 above).

Next, the other surface of the second silicon substrate 121 is etched to form the solder seat 124. The solder seating portion 124 seats the second solder portion 127, which will be described later, and serves to reduce the air gap while ensuring the thickness of the solder.

The solder seat 124 may be etched on the other surface of the second silicon substrate 121 to recess a predetermined depth at a position corresponding to the first solder 115 of the membrane 110 when bonded to the membrane 110. It can form by doing (S22 above).

Next, a thermal oxide film 125 for insulation is formed in the etched regions on both sides of the second silicon substrate 121, and the second electrode 126 and the second wet layer 126a are disposed on the solder seat 124. ). The second electrode 126 can be formed, for example, by depositing a Ti / Au (2000 Pa / 1000 Pa) thin film by e-beam evaporation (above S23).

Next, a second solder portion 127 is formed on the second wetting layer 126a. The second solder part 127 is bonded to the first solder part 115 to serve to connect the membrane part 110 and the back plate part 120 to each other.

As described above, in the case where Au solder is used as the first solder portion 115, the second solder portion 127 can use Sn solder. Of course, the material of the 1st solder part 115 and the 2nd solder part 127 is not limited to Au / Sn, Any alloy can be used as long as it is an alloy which can be eutectic.

Thereafter, an acoustic hole 128 is formed in the back plate 123. The acoustic hole 128 serves to reduce the air layer attenuation value due to the resonance of the membrane unit 110 and may be configured by forming a plurality of holes (S24). On the other hand, the acoustic hole 128 can be formed using a DRIE. In addition, it is possible to form a slot (not shown) for external electrode connection in the back plate 123 by a simultaneous process.

3. The third step

3 is a cross-sectional view of a MEMS microphone manufactured according to the MEMS microphone manufacturing method of FIG. 1.

Referring to FIG. 3, the MEMS microphone 100 is manufactured by connecting the membrane unit 110 and the back plate unit 120. The connection between the membrane part 110 and the back plate part 120 may be performed by eutectic bonding the first solder part 115 and the second solder part 127. For example, after aligning the membrane unit 110 and the back plate unit 120 in a junction aligner, it may be eutectic seal bonding at about 300 ℃. Since the eutectic point of the Au / Sn alloy constituting the solder portions 115 and 127 is about 280 ° C, eutectic bonding is possible at 300 ° C.

The air gap g refers to an air layer between the first electrode 114 and the second electrode 126, and the thickness of the air gap g greatly affects the acoustic performance of the microphone. MEMS microphone manufacturing method (S) according to an embodiment of the present invention has the effect of reducing the air gap (g) than conventional, while ensuring the solder thickness for stable bonding without reducing the size of the solder.

Hereinafter, a method of manufacturing a MEMS microphone according to another embodiment of the present invention will be described. On the other hand, repeated description of the same configuration or method as the above embodiment will be omitted.

Figure 4 is a flow chart of a MEMS microphone manufacturing method (S1) according to another embodiment of the present invention.

Referring to FIG. 4, the MEMS microphone manufacturing method S1 is performed in parallel with the first step S100 of manufacturing the membrane portion 210 and the first step S100, and manufactures the back plate portion 220. A second step (S200) and the third step (S300) for connecting the membrane portion 210 and the back plate 220. Hereinafter, each step will be described in detail.

1. The first step

FIG. 5A is a cross-sectional view illustrating a manufacturing procedure of the membrane part 210 according to the MEMS microphone manufacturing method S1 of FIG. 4 according to processes.

Referring to FIG. 5A, an oxide film 212 and a first nitride film 213 are deposited on both surfaces of the first silicon substrate 211, and one surface of the first silicon substrate 211 is etched to form a solder seat 216. . That is, in the above-described embodiment, the solder seating portion is formed in the back plate portion, but in this embodiment, the solder seating portion 216 is formed in the membrane portion 210.

The solder seating portion 216 has a predetermined depth on one surface of the first silicon substrate 211 at a position corresponding to the second solder portion 227 of the back plate portion 220 when bonded to the back plate portion 220 to be described later. It can be formed by etching so as to be recessed (S110 above).

Next, a first thermal oxide film 217 for insulation is formed on the solder seat 216, and a first electrode 214 and a first wet layer 214a are formed on the first thermal oxide film 217. (S120) (or more S120).

Next, the first solder part 215 is formed on the first wetting layer 214a, and the other surface of the first silicon substrate 211 is etched to manufacture the membrane part 210. The oxide film 212, the first nitride film 213, the solder seat 216, the thermal oxide film 217, the first electrode 214, the first wet layer 214a, and the first solder part 215 are described above. The same or similar to the embodiment, detailed description thereof will be omitted.

2. Second Step

FIG. 5B is a cross-sectional view illustrating a manufacturing procedure of the back plate unit 220 according to the process of manufacturing the MEMS microphone S1 of FIG. 4.

Referring to FIG. 5B, a second nitride film 222 is deposited on both surfaces of the second silicon substrate 221 and one surface is etched to form a back plate 223 (above S210).

Next, a second thermal oxide film 225 for insulation is formed in the etched region, and a second electrode 226 and a second wetting layer 226a are formed on both sides of the second silicon substrate 221. The second electrode 226 is formed at a position corresponding to the first electrode 214 of the membrane portion 210 (or more S220).

Next, the second solder part 227 is formed on the second wetting layer 226a, and the sound hole 228 is formed in the back plate 223 to manufacture the back plate part 220 (above S230). . The second nitride film 222, the thermal oxide film 225, the second electrode 226, the second wetted layer 226a, the second solder portion 227 and the acoustic hole 228 are the same or similar to the above-described embodiment. The detailed description will be omitted. On the other hand, it is possible to form a slot (not shown) for connecting the external electrode in the back plate 2123 in a simultaneous process.

3. The third step

FIG. 6 is a cross-sectional view of the MEMS microphone 200 manufactured according to the MEMS microphone manufacturing method S1 of FIG. 4.

Referring to FIG. 6, the MEMS microphone 200 is manufactured by connecting the membrane portion 210 and the back plate portion 220. The connection method is the same or similar to the above-described embodiment. MEMS microphone manufacturing method (S1) according to another embodiment of the present invention has the effect of reducing the air gap (g), while ensuring the solder thickness for stable bonding without reducing the size of the solder.

Hereinafter, a modification of the MEMS microphone a manufactured according to the MEMS microphone manufacturing method S1 of FIG. 4 will be described. On the other hand, repeated description of the same configuration or method as the above embodiment will be omitted.

7 is a cross-sectional view showing a modification of the MEMS microphone (a) manufactured according to the MEMS microphone manufacturing method (S1) of FIG.

Referring to FIG. 7, the MEMS microphone (a) may form inclined surfaces corresponding to each other on the membrane portion 210 and the back plate portion 220 to align and bond the same.

The inclined surface may be formed when the solder seat 217 is formed. For example, the solder seat 217 may include a plane 217a and a first inclined surface 217b. The plane 217a corresponds to a flat surface on which the first solder portion 215 is disposed, and the first inclined surface 217b corresponds to a surface inclined from the plane 217a onto the first silicon substrate 211.

Meanwhile, when etching the other surface of the second silicon substrate 221, a plane 221a on which the second solder part 227 is disposed and a second inclined surface 221b inclined to correspond to the first inclined surface 217b may be formed. have.

That is, the first inclined surface 217b formed on the membrane portion 210 and the second inclined surface 221b formed on the back plate portion 220 may be aligned and bonded to abut each other. In this case, there is an effect that the membrane portion 210 and the back plate 220 can be accurately and simply aligned and bonded without using a separate aligner.

On the other hand, the area where the first inclined surface 217b and the second inclined surface 221b abut can be sealed to prevent air from leaking out.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, many modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

100,200,300: MEMS microphone
110,210: membrane portion 111,211: first silicon substrate
112,212: oxide film 113,213: first nitride film
114,214: first electrode 114a, 214a: first wet layer
115,215: first solder portion
216: solder seat 217: thermal oxide film
120,220: back plate portion 121,221: second silicon substrate
122,222: second nitride film 123,223: back plate
124,224: solder seat 125,225: thermal oxide film
126,226: second electrode 126a, 226a: second wet layer
127,227: second solder portion
128,228: Sound hole g: Air gap
216a and 221a: plane 216b: first inclined surface
221b: second slope

Claims (9)

The first electrode 114 and the first wetting layer 114a are formed on the first nitride film 113 formed on one surface of the first silicon substrate 111 on which the oxide film 112 and the first nitride film 113 are sequentially deposited on both surfaces. Forming a step (S11);
Forming a first soldering portion (115) on the first wetting layer (114a) (S12); And
A first step (S10) of manufacturing a membrane part (110), including etching the other surface of the first silicon substrate (111) (S13);
In parallel with the first step (S10), the step of forming a back plate (123) by etching one surface of the second silicon substrate 121, the second nitride film 122 is deposited on both surfaces (S21);
Etching the other surface of the second silicon substrate 121 to form a solder seating portion 124 (S22);
A thermal oxide film 125 is formed in the etched regions on both sides of the second silicon substrate 121, and a second electrode 126 and a second wetting layer 126a are formed on the solder seat 124. Step S23; And
Forming a second solder part 127 on the second wetting layer 126a and forming an acoustic hole 128 in the back plate 123 (S24). Manufacturing a second step (S20); And
And a third step S30 of joining the first solder part 115 and the second solder part 127 to connect the membrane part 110 and the back plate part 120. MEMS microphone manufacturing method.
Etching one surface of the first silicon substrate 211 on which the oxide film 212 and the first nitride film 213 are sequentially deposited on both surfaces to form a solder seating portion 216 (S110);
Forming a first thermal oxide film 217 on the solder seat 216 and forming a first electrode 214 and a first wet layer 214a on the first thermal oxide film 217 (S120). ); And
Forming a first solder part 215 on the first wetting layer 214a and etching the other surface of the first silicon substrate 211 (S130) to manufacture the membrane part 210. Step S100;
In parallel with the first step (S100), a step of forming a back plate (223) by etching one surface of the second silicon substrate (221) on which the second nitride film (222) is deposited on both surfaces (S210);
Forming a second thermal oxide film 225 on the etched region and forming a second electrode 226 and a second wet layer 226a on both sides of the second silicon substrate 221 (S220); And
Forming a second solder part 227 on the second wetting layer 226a and forming an acoustic hole 228 in the back plate 223 (S230). Manufacturing a second step (S200); And
And a third step (S300) of joining the first solder part 215 and the second solder part 227 to connect the membrane part 210 and the back plate part 220. MEMS microphone manufacturing method.
The method according to claim 1 or 2,
The first solder portion is Au solder, the second solder portion is Sn solder,
The first solder portion and the second solder portion is connected to the MEMS microphone manufacturing method, characterized in that carried out above the eutectic point temperature of Au-Sn.
The method of claim 2,
Formation of the solder seat 216 is,
A plane 216a on which the first solder portion 215 is disposed;
Etching is performed such that a first inclined surface 216b inclined from the plane 216a to the upper portion of the first silicon substrate 211 is formed.
The other surface of the second silicon substrate 221 on the plane 221a on which the second solder portion 227 is disposed;
And etching the second inclined surface (221b) to be inclined to correspond to the first inclined surface (216b).
The method of claim 4, wherein
The third step (S300),
And aligning and bonding the first inclined surface (216b) of the membrane portion (210) and the second inclined surface (221b) of the back plate portion (220) to abut each other.
6. The method of claim 5,
And sealing the area where the first inclined surface (216b) and the second inclined surface (221b) contact each other.
The membrane part 110 vibrating according to external sound pressure, the back plate part 120 coupled to the membrane part 110, and the first solder part bonding the membrane part 110 and the back plate part 120 to each other. In the MEMS microphone including the 115 and the second solder portion 127,
MEMS microphone, characterized in that the upper portion of the back plate portion 120 is formed with a solder mounting portion 125 is recessed and seated in the second solder portion (127).
A membrane portion 210 vibrating according to an external sound pressure, a back plate portion 220 coupled to the membrane portion 210 and a first solder portion for bonding the membrane portion 210 and the back plate portion 220 to each other. In the MEMS microphone including the 215 and the second solder portion 227,
MEMS microphone, characterized in that the lower portion of the membrane portion 210 is formed with a solder seat portion 217, the first solder portion 215 is recessed and seated.
The method of claim 8,
The solder seat 217 is,
A plane 217a on which the first solder portion 215 is disposed; And
A first inclined surface 217b inclined from the plane 217a to the upper portion of the membrane portion 210,
The back plate portion 220 is a MEMS microphone, characterized in that it comprises a second inclined surface (221b) inclined to correspond to the first inclined surface (216b).

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