KR20180064960A - Voice transmitting device and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a sound transfer device and a manufacturing method thereof. Since a dent unit formed on a vibration plate has a side wall having the width becoming narrow toward a lower surface, and the side wall of the dent unit is formed at a position not being in contact with the edge of a base substrate when the vibration plate vibrates, thereby improving vibration efficiency and durability of the vibration plate.

Description

TECHNICAL FIELD [0001] The present invention relates to a voice transmission device and a method for manufacturing the same,

The present invention relates to an acoustic transducer manufactured to have a diaphragm (membrane or diaphragm) vibrating by a negative pressure with good vibration efficiency at an operating voltage and excellent durability, and a manufacturing method thereof.

Generally, a voice transmission apparatus includes a microphone as an apparatus for converting an acoustic signal into an electrical signal. Microphones are available in a wide variety of materials, depending on the material and operating principle. Depending on the material, it can be classified into a carbon microphone, a crystal microphone, and a magnetic microphone. Depending on the operation principle, it can be classified into a dynamic microphone using an induced electromotive force by a magnetic field and a condenser microphone using a capacitance change due to vibration of the membrane.

2. Description of the Related Art Micro condenser microphones such as ECM (Electret Condenser Microphone) and MEMS (Micro Electro Mechanical System) microphones are mainly used in portable or small electronic devices such as computers, mobile communication terminals, MP3 sound recorders, cassette recorders, camcorders and headsets. The ECM microphone uses a polarizable dielectric material called an electret. The ECM microphone has a function of accumulating charge while the bias voltage is not applied. Electronic charge of the electret material is sensitive to temperature and deteriorates microphone sensitivity due to long-term drift. Thus, although Teflon is applied to a microphone as an electret material, applying Teflon to a standard mass production process has caused many difficult problems and has caused deterioration of product performance.

On the other hand, a condenser microphone does not require an electret material, but a bias voltage may be applied to accumulate electric charges. Condenser microphones have appropriate sensitivity and low sensitivity to temperature changes. Because it is usually manufactured by MEMS (Micro-Electro-Mechanical System) process for small size and low cost mass production, condenser microphone is sometimes referred to as membrane microphone.

The condenser microphone includes two plate capacitances: a diaphragm (membrane or diaphragm) and a back plate, and the two plate capacitances are separated through an air gap acting as an insulating material. A back chamber is formed on the base substrate supporting the diaphragm (membrane or diaphragm) and the back plate. A plurality of acoustic holes are formed on the back plate to reduce air damping. The sound waves (or acoustic signals) introduced through the acoustic holes of the back plate cause the diaphragm (membrane or diaphragm) to bend, and the capacitance between the diaphragm (membrane or diaphragm) and the back plate changes with the change of the air gap . A readout circuit is constructed to appropriately change the capacitance change by an electrical signal. Microphone commercialization manufacturers have continued to improve the structure and materials of diaphragms (membranes or diaphragms) and backplates to improve sensitivity and reduce noise levels.

The condenser microphone (or MEMS microphone) must maintain efficient vibration of the diaphragm (membrane or diaphragm) to minimize the parasitic capacitance and increase the vibration efficiency of the diaphragm (membrane or diaphragm).

Figs. 1A, 1B, and 1C show a structure of a base board, a vibration plate, and a back plate of a conventional condenser microphone (or a MEMS microphone). As shown in FIGS. 1A, 1B, and 1C, the diaphragm 110 contacts the base substrate 100 with some areas 111A, 111B, and 111C, and maintains a distance from the base substrate 100 in a bent form Respectively.

1A shows a case where sound waves are transmitted to a diaphragm 110 positioned at a lower end of a back plate 120 so that the diaphragm 110 vibrates vertically and repeatedly contacts the inner edge A1 of the back chamber in the base substrate 100 Causing the diaphragm 110 to be damaged. 1B shows that when the diaphragm 110 approaches the back plate 120, the membrane electrode 112 of the diaphragm 110 and the opposing electrode 122 of the back plate 120 become abnormally close to cause a contact A2 .

1C shows a case where the area of the contact portion 111C of the diaphragm 110 is narrow and the contact portion 111C of the vibration plate 110 is lifted off and deformation may occur in the side wall A3 of the contact portion 111C I have possession. The structure of the partial contact type diaphragm is as follows. 1) When there is a problem in stiffness, the vibration width of the diaphragm 110 becomes narrow. 2) When the contact area of the diaphragm contact portion is narrow, 3) Due to the narrow air gap between the diaphragm and the back plate, a part of the diaphragm may repeatedly contact and break the back chamber edge A1, or the membrane electrode 112 and the back plate 120 may face each other The electrode 122 may approach abnormally and may biasedly impact.

Referring to FIG. 2, the condenser microphone (or the MEMS microphone) must maximize the capacitance between the back plate 120 and the diaphragm 110 with respect to the voice signal, and minimize the leakage capacitance. The leakage capacitance typically generated during operation is determined by the parasitic capacitance CP1 generated in the insulating connection portion 130B between the back plate 120 and the diaphragm 110 and the insulation between the diaphragm 110 and the base substrate 100 And a parasitic capacitance (CP2) generated in the connection part 130A. In addition, there is an unnecessary capacitance generated in the wire connecting the microphone body and the pad. It is an important task to maximize the flat plate capacitance Cmic between the back plate 120 and the diaphragm 110 through design and process improvement as much as possible.

Korean Patent Publication No. 10-2016-0127212 (Publication date 2016.11.03)

In order to solve the problems of the related art, the present invention provides a voice transmission device including a condenser microphone with good vibration efficiency of a diaphragm at an operating voltage and excellent durability, and a method of manufacturing the same.

In addition, the present invention provides a voice transmission apparatus including a microphone excellent in low frequency band sensitivity and a method of manufacturing the same.

According to an aspect of the present invention, there is provided a voice transmission apparatus including: a base substrate having a back chamber formed therein; A diaphragm having a membrane electrode on a back chamber of the base substrate; An opposite electrode facing the membrane electrode of the diaphragm and an air gap, and a back plate formed with a plurality of acoustic holes,

Wherein the diaphragm has a first wall having a side wall contacting with a lower surface of the diaphragm, the diaphragm having a narrower width as the length of the diaphragm increases in a direction perpendicular to the longitudinal direction of the membrane electrode, A side wall of the first depressed portion is formed at a position where the side wall of the first depressed portion does not contact the edge of the base substrate when the diaphragm vibrates,

Wherein the back plate has a second depressed portion having a side wall narrower in the direction perpendicular to the longitudinal direction of the opposing electrode at a portion facing the first depressed portion of the diaphragm, And protrusions are formed in the periphery of the second depression at a length shorter than the width of the air gap in a direction perpendicular to the longitudinal direction of the counter electrode.

In addition, the first depression of the diaphragm according to the present invention is realized as one band when viewed from above, and a plurality of slits are formed on the side wall of the first depression.

Further, the plurality of slits formed in the first depression of the diaphragm according to the present invention are formed such that the straight slit and the refractive slit are adjacent to each other. The refraction type slit includes a first rectilinear section, a first bend section connected to the first rectilinear section, a second bend section connected to the first bend section, and a second rectilinear section connected to the second bend section .

The diaphragm according to the present invention is characterized in that a support portion extending downward from the bottom surface of the first depression is formed.

In addition, the diaphragm according to the present invention is characterized in that a plurality of through holes penetrating the back chamber of the base substrate upward and downward are formed in the peripheral portion of the first depression.

Further, in the case where a plurality of slits are formed on the side wall of the depression, the side wall inclination of the depression is not less than 15 degrees and not more than 60 degrees with respect to the vertical direction of the diaphragm, and a plurality of slits are not formed on the side walls The sidewall inclination of the depressed portion is formed to be not less than 50 degrees and not more than 80 degrees with respect to the vertical direction of the diaphragm.

According to another aspect of the present invention, there is provided a method of manufacturing a voice transmission device, comprising the steps of: a) growing an insulating sacrificial material on a surface of a base substrate by a pressure chemical vapor deposition method at a first temperature to form a first sacrificial layer, Growing the first sacrificial layer by a pressure sensitive chemical vapor deposition method at a second temperature higher than the first temperature to form a second sacrificial layer;

b) wet etching the second sacrificial layer to form a first depression including a sidewall that narrows from the second sacrificial layer to the first sacrificial layer; c) forming a membrane layer on the surface of the second sacrificial layer on which the first depression is formed; d) dry-etching the membrane layer and a portion of the second sacrificial layer; e) forming a membrane electrode in the center of the membrane layer, and forming a pad for bias voltage in the portion etched in step d);

f) forming a third sacrificial layer by growing an insulating sacrificial material on the surface of the membrane layer formed in step e) by chemical vapor deposition, and forming a counter electrode at the center of the third sacrificial layer; g) wet etching the third sacrificial layer formed in step f) to form a second depression including a sidewall that narrows from the third sacrificial layer to the membrane layer;

h) wet etching the bottom surface of the second depression of the third sacrificial layer formed in the step g) or the third sacrificial layer around the second depression, and depositing a silicon nitride film by chemical vapor deposition to form a backplate film Wow; i) wet-etching the backplate film formed in step h) to form a plurality of acoustic holes;

j) wet-etching the backplate layer and a part of the third sacrificial layer, and forming a pad for an output voltage in the wet-etched portion; k) removing the first, second, and third sacrificial layers and the back surface of the base substrate by wet etching to form an air gap between the membrane layer and the back plate membrane, And forming a back chamber.

According to the above configuration, the voice transmission apparatus and the method of manufacturing the same according to the present invention have the following effects.

First, the sidewall of the depression is formed at a position where the depression formed on the diaphragm does not contact the edge of the base substrate when the diaphragm vibrates, thereby improving the vibration efficiency and durability of the diaphragm. do.

Second, since the projections are formed on the bottom surface or the periphery of the depressed portion formed on the back plate, it is possible to prevent the membrane electrode of the diaphragm and the counter electrode of the back plate from approaching abnormally when the diaphragm vibrates. Particularly, the protrusion of the back plate presses the diaphragm, thereby preventing the diaphragm from being detached from the base substrate and maintaining the vertical vibration.

Thirdly, since the plurality of slits are formed on the side wall of the depression formed in the diaphragm, when the diaphragm is vibrated, the vertical vibration is improved by increasing the flexibility in the vertical direction, and the post- Improvement is possible. In particular, a ventilation effect capable of improving the low frequency can be obtained.

Fourth, since a plurality of micro-projections are formed on the bottom surface of the depression formed in the diaphragm, the area of contact with the base substrate is small, thereby reducing the leakage capacitance (or parasitic capacitance) during operation of the diaphragm and increasing the plate capacitance.

Fifth, since the support portion is formed on the bottom surface of the depression of the diaphragm so as to be spaced apart from the surface of the base substrate by a height of 0.1 m or more and 10 m or less, the leakage capacitance (or parasitic capacitance) And improves the flowability and vibration efficiency of the diaphragm.

Sixth, in the case where a plurality of slits are formed on the side wall of the depression of the diaphragm, when the side wall inclination of the depression is not less than 15 degrees and not more than 60 degrees with respect to the vertical direction of the diaphragm, The inclination is formed to be not less than 50 degrees and not more than 80 degrees with respect to the vertical direction of the diaphragm, thereby preventing breakage during operation of the diaphragm and improving the movement in the vertical direction.

Seventh, the air discharge accumulated in the air gap can be easily adjusted by forming a plurality of through holes passing through the back chamber of the base substrate up and down at the periphery of the depression of the diaphragm.

Figs. 1A, 1B and 1C show a structure of a base board, a vibration plate and a back plate of a conventional condenser microphone (or MEMS microphone).
2 is an exemplary diagram for explaining the parasitic capacitance of a conventional condenser microphone (or a MEMS microphone).
3 is an exemplary diagram illustrating a structure of a condenser microphone included in a voice transmission apparatus according to an embodiment of the present invention.
Figs. 4 to 7, Figs. 8A and 8B are diagrams for explaining the process of manufacturing the condenser microphone of Fig.
FIGS. 9A and 9B are diagrams for explaining a process of manufacturing a condenser microphone, which is different from FIG. 3. FIG.
FIG. 10 is an exemplary view for explaining a top view of the diaphragm 110 of the condenser microphone according to FIG.
11A and 11B are diagrams for explaining a cross section taken along line AA in FIG.
12 is an exemplary view for explaining a shape of a diaphragm 110 of another condenser microphone according to the present invention viewed from above.
13A and 13B are diagrams for explaining a cross section taken along line BB in FIG.
14A and 14B are diagrams for explaining the shape of the diaphragm 110 of another condenser microphone according to the present invention viewed from above.
Figs. 15A and 15B are diagrams for explaining a cross section taken along line X'-X 'in Fig. 14A and line X'-Y' in Fig. 14B.
16A and 16B are diagrams for explaining a shape of the diaphragm 110 of another condenser microphone according to the present invention viewed from above.
Figs. 17A and 17B are diagrams for explaining a cross section taken along line X'-X 'in Fig. 16A and line X "-Y" in Fig. 16B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

As shown in FIG. 3, the condenser microphone included in the voice transmission apparatus according to the present invention includes a base substrate 100 on which a back chamber 101 penetrating upward and downward is formed, The diaphragm 110 having the membrane electrode 112 and the membrane electrode 112 of the diaphragm 110 are opposed to each other with an air gap therebetween on a back chamber 101 of the membrane electrode assembly 100, And an electrode 122 and a back plate 120 having a plurality of acoustic holes.

It is preferable that the base substrate 100 is implemented as a silicon wafer substrate when it is judged by taking all of the characteristics, physical properties, process easiness, and manufacturing cost of the condenser microphone into consideration. The back plate 120 may be formed of a polysilicon or silicon nitride film. The diaphragm 110 may be formed of polysilicon or a material mainly composed of silicon (e.g., SiO2).

The diaphragm 110 is formed with a depression 110A '. The depressed portion 110A 'is formed in a portion of the diaphragm 110 that faces the remaining region of the base substrate except for the back chamber 101. The depression 110A 'of the diaphragm 110 includes a side wall 1110A' that becomes narrower in width in a direction perpendicular to the longitudinal direction of the membrane electrode 112. The inclination of the sidewall of the depression 110A 'is realized by not less than 15 degrees and not more than 60 degrees with respect to the vertical direction of the diaphragm.

The diaphragm 110 is formed at a position where the side wall 1110A 'of the depression 110A' does not contact the edge A1 of the base substrate 100 when the diaphragm vibrates, as shown in Fig. A plurality of slits 113 may be formed in the side wall 1110A 'of the depression 110A'. The plurality of slits 113 improves vertical flexibility when the diaphragm 110 is vibrated, thereby improving the vertical vibration and improving the post-packing sensitivity by acting as a discharge passage for negative pressure.

A supporting portion extending downward from the bottom surface of the depression 110A 'of the diaphragm 110 may be formed. A plurality of fine protrusions 110B 'may be formed on the bottom surface of the depression 110A', as shown in FIG. Since the support portion is formed of a plurality of fine protrusions 110B ', the area of contact with the base substrate 100 is small, thereby reducing the leakage capacitance (or parasitic capacitance) during operation of the diaphragm and increasing the plate capacitance.

The back plate 120 is provided with a depressed portion having a side wall that becomes narrower as the length is extended in a direction perpendicular to the longitudinal direction of the counter electrode 122 at a portion of the diaphragm 110 facing the depressed portion 110A ' 120A 'are formed. As shown in FIG. 3, a protrusion 120B 'may be formed on the bottom surface of the depressed portion 120A' of the back plate 120 to have a length shorter than the width of the air gap.

The protrusion 120B 'is formed in the depression 120A' formed in the back plate 120 so that the membrane electrode 112 of the diaphragm 110 is opposed to the back plate 120 of the diaphragm 110 when the diaphragm 110 vibrates. It is possible to prevent the electrode 122 from approaching abnormally. Particularly, the protrusion 120B 'of the back plate 120 presses the diaphragm 110 to prevent the diaphragm 110 from escaping from the base substrate 100 and to maintain the vertical vibration.

Figs. 4 to 7, Figs. 8A and 8B are diagrams for explaining the process of manufacturing the condenser microphone of Fig.

4, a first sacrificial layer 130 is formed by growing an insulating sacrificial material on the surface of a base substrate 100 by a pressure sensitive chemical vapor deposition method at a first temperature (for example, 400 degrees) 130 to form a second sacrificial layer 140 by a CVD method at a second temperature (e.g., 800 degrees) higher than the first temperature (e.g., 400 degrees).

5, the first depressed portion 110A including the sidewalls narrowed in width from the second sacrificial layer 140 to the first sacrificial layer 130 is wet-etched into the second sacrificial layer 140, . For example, one support groove can be formed by wet-etching from the bottom surface of the first depression 110A to the surface of the base substrate 100. In another example, in FIG. 5, a plurality of support grooves 110B may be formed by selectively patterning and dry etching the bottom surface of the first depression 110A to the surface of the base substrate 100. [

6, the membrane layer 110 is formed on the surface of the second sacrificial layer 140 where the first depression 110A is formed. A depression 110A 'corresponding to the first depression 110A formed in the second sacrificial layer 140 is formed in the membrane layer 110. [ In addition, a plurality of fine protrusions 110B 'corresponding to the plurality of support grooves 110B can be formed.

Referring to FIG. 7, a membrane electrode 112 is formed at the center of the membrane layer 110. The membrane layer 110 and a part of the second sacrificial layer 140 are dry-etched, and a pad 114 for a bias voltage is formed by selective patterning.

Hereinafter, a process of forming the back plate film and the air cap will be described with reference to FIGS. 8A and 8B.

8A, a third sacrificial layer 150 is formed by growing an insulating sacrificial material on the surface of the membrane layer 110 formed as shown in FIG. 7 by chemical vapor deposition, and a third sacrificial layer 150 is formed on the center of the third sacrificial layer 150, Electrode 122 is formed.

Then, the third sacrificial layer 150 is wet-etched to form a second depression including side walls narrowing from the third sacrificial layer 150 toward the membrane layer 110, and a third sacrificial layer 150 are wet-etched, and a silicon nitride film is deposited by chemical vapor deposition to form a backplate film 120. The depression 120A 'corresponding to the second depression formed in the third sacrificial layer 150 is formed in the backplate 120. [ In addition, a protrusion 120B 'is formed in a portion where the bottom surface of the second depression is wet-etched.

Although not shown in FIG. 8A, a plurality of acoustic holes are formed in the backplate film 120 including the counter electrode 122 by selective patterning. A part of the backplate 120 and the third sacrificial layer 150 are wet-etched and a pad 115 for an output voltage is formed on the wet-etched portion.

8B, the back surfaces of the first, second, and third sacrificial layers 130, 140, and 150 and the base substrate 100 are removed by wet etching to form a gap between the membrane layer 110 and the backplate membrane 120 An air gap is formed, and a back chamber 101 is formed on the base substrate 100.

FIGS. 9A and 9B are diagrams for explaining a process of manufacturing a condenser microphone, which is different from FIG. 3. FIG. Here, the processes of FIGS. 4 to 7 are the same. 7, a membrane electrode 112 is formed at the center of the membrane layer 110, a part of the membrane layer 110 and a part of the second sacrificial layer 140 are dry-etched, a bias is applied to the etched part, The process for forming the voltage pad 114 is the same.

9A, a third sacrificial layer 150 is formed by growing an insulating sacrificial material on the surface of the membrane layer 110 by chemical vapor deposition, and the third sacrificial layer 150 The counter electrode 122 is formed.

Then, the third sacrificial layer 150 is wet-etched to form a second depression including side walls narrowing from the third sacrificial layer 150 toward the membrane layer 110, and a third sacrificial layer 150 are wet-etched, and a silicon nitride film is deposited by chemical vapor deposition to form a backplate film 120. The depression 120A 'corresponding to the second depression formed in the third sacrificial layer 150 is formed in the backplate 120. [ In addition, a protrusion 120B 'is formed in a portion wet-etched around the second depression.

Although not shown in FIG. 9A, a plurality of acoustic holes are formed in the backplate film 120 including the counter electrode 122 by selective patterning. A part of the backplate 120 and the third sacrificial layer 150 are wet-etched and a pad 115 for an output voltage is formed on the wet-etched portion.

9B, the back surfaces of the first, second, and third sacrificial layers 130, 140, and 150 and the base substrate 100 are removed by wet etching to form a gap between the membrane layer 110 and the backplate membrane 120 An air gap is formed, and a back chamber 101 is formed on the base substrate 100.

FIG. 10 is an exemplary view for explaining a top view of the diaphragm 110 of the condenser microphone according to FIG. 3, and FIGS. 11a and 11b are illustrations for explaining a cross section taken along the line A-A in FIG.

As shown in the figure, the side wall 1110A 'of the depression of the diaphragm 110 is formed in a single band shape when viewed from above. A plurality of slits 113 having an opening structure are formed on the side wall 1110A 'of the depression of the diaphragm 110 so as to be spaced apart from each other. The plurality of slits 113 are formed such that the linear slit 113A and the refractive slit 113B are adjacent to each other. The refraction type slit 113B includes a first straight portion, a first bent portion connected to the first straight portion, a second bent portion connected to the first bent portion, and a second straight line connected to the second bent portion. Section. A plurality of slits 113 are formed on the side wall 1110A 'of the depression formed in the diaphragm 110 so as to improve the vertical flexibility when the diaphragm 110 vibrates to improve the vertical vibration , It serves as a discharge path of sound pressure, and it is possible to improve the sensitivity after packing.

As shown in Fig. 11A, a plurality of fine protrusions 111B 'may be formed on the bottom surface of the depressed portion. As shown in FIG. 11B, the plurality of fine protrusions 111B 'may be spaced apart from the surface of the base substrate 100 by a height of not less than 0.1 μm and not more than 10 μm.

As shown in FIG. 10, the bottom surface 1100D 'of the depression formed in the diaphragm 110 can also be realized as a single band when viewed from above. A plurality of fine protrusions 111B 'may be formed on the bottom surface 1100D' of the dimples so as to be spaced apart from each other by a predetermined distance. The membrane electrode 112 formed on the diaphragm 110 is connected to the pad 1140 for bias voltage and the connector 114A.

FIG. 12 is an exemplary view for explaining a top view of a diaphragm 110 of another condenser microphone according to the present invention, and FIGS. 13A and 13B are illustrations for explaining a cross section taken along a line B-B in FIG.

As shown in FIG. 12, the side wall 1110A 'of the depression of the diaphragm 110 and the bottom surface 1100D' of the depression are realized as one band when viewed from above. The inclination of the sidewall of the depression 110A 'is realized in the range of 15 ° to 60 ° with respect to the vertical direction of the diaphragm. As shown in FIGS. 13A and 13B, the bottom surface 1100D' An extending supporting portion 111C 'is formed. The support 111C 'is also implemented as a single band when viewed from above. The membrane electrode 112 formed on the diaphragm 110 is connected to the pad 1140 for bias voltage and the connector 114A.

13A and 13B, a plurality of slits 113 having an opening structure are formed on the side wall 1110A 'of the depression of the diaphragm 110 so as to be spaced apart from each other. The plurality of slits 113 are formed such that the linear slit 113A and the refractive slit 113B are adjacent to each other. The refraction type slit 113B includes a first straight portion, a first bent portion connected to the first straight portion, a second bent portion connected to the first bent portion, and a second straight line connected to the second bent portion. Section.

As shown in Fig. 13A, a supporting portion 111C 'may be formed on the bottom surface of the depressed portion. 13B, the support portion 111C 'may be formed to be spaced apart from the surface of the base substrate 100 by a height of not less than 0.1 mu m and not more than 10 mu m height 111B ".

14A and 14B are diagrams for explaining a top view of the diaphragm 110 of another condenser microphone according to the present invention. FIGS. 15A and 15B are diagrams for explaining the X'-X 'line of FIG. 14A and FIG. Sectional view taken along line X "-Y ".

As shown in FIGS. 14A, 14B, 15A, and 15B, a slit is not formed in the side wall 1110A 'of the depression of the diaphragm 110 of the present invention, and a plurality of microprojections 110B' .

15B, the supporting portion 111C 'is formed on the bottom surface 1100D' of the depression of the diaphragm 110 so as to have a height of not less than 0.1 mu m and not more than 10 mu m in height 111B " As shown in FIG.

FIGS. 16A and 16B are views for explaining a top view of the diaphragm 110 of another condenser microphone of the present invention. FIGS. 17A and 17B are views for explaining the X'-X 'line of FIG. 16A and FIG. Sectional view taken along line X "-Y ".

16A, 16B, 17A and 17B, there is no slit in the side wall 1110A 'of the depression of the diaphragm 110 of the present invention, and a slit is formed in the periphery of the depression 110A' A plurality of through holes 1130 penetrating upward and downward are formed in a back chamber 101 of the backlight unit 100. A plurality of through holes 1130 are formed in the periphery of the depression of the diaphragm 110 so as to penetrate the back chamber 101 of the base substrate 100 upwardly and downwardly so as to facilitate the discharge of air accumulated in the air gap .

17B, the bottom surface 1100D 'of the depressed portion 110A' of the diaphragm 110 has a height of not less than 0.1 mu m and not more than 10 mu m in height 111B "with respect to the surface of the base substrate 100 May be spaced apart.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined only by the appended claims.

100: Base substrate
101: back chamber
110: diaphragm
112: membrane electrode
120: Back Plate
122: opposing electrode
130A, 130B, 130, 140: sacrificial layer
Cp1, Cp2: Parasitic Capacitance
Cmic: Capacitance between opposing electrodes
110A ': Depression
110B ', 111B': micro-projections
111B ": separation distance
111C ': Support
120A ': a depression of the back plate
120B ': protrusion
113: slit
113A: Straight slit
113B: refraction type slit
1130: discharge hole (or through hole)
114, 1140: Pads for bias voltage
114A: Connector
115: Pad for output voltage
160: air gap

Claims (20)

A base substrate on which a back chamber is formed; A diaphragm having a membrane electrode on a back chamber of the base substrate; An acoustic transducer including an opposite electrode facing the membrane electrode of the diaphragm and an air gap, and a back plate formed with a plurality of acoustic holes,
The diaphragm includes:
A first depressed portion having a side wall narrower in width in a direction perpendicular to the longitudinal direction of the membrane electrode is formed at a portion of the base substrate other than the back chamber,
A side wall of the first depression is formed at a position where the diaphragm does not contact the edge of the base substrate when the diaphragm vibrates,
The back plate includes:
A second depressed portion having a side wall narrower in width in a direction perpendicular to the longitudinal direction of the counter electrode is formed at a portion of the diaphragm facing the first depressed portion,
Wherein protrusions are formed on the bottom surface of the second depressed portion or around the second depressed portion in a direction perpendicular to the longitudinal direction of the counter electrode to a length shorter than the width of the air gap,
And an acoustic transducer. The method according to claim 1,
Wherein a side wall inclination of the first depressed portion is not less than 50 degrees and not more than 80 degrees with respect to a vertical direction of the diaphragm,
And an acoustic transducer. The method according to claim 1,
Wherein the first depression of the diaphragm is embodied as a single band when viewed from above,
A plurality of slits are formed on the side wall of the first depression,
And an acoustic transducer. The method of claim 3,
The side wall inclination of the first depressed portion is not less than 15 degrees and not more than 60 degrees based on the vertical direction of the diaphragm,
And an acoustic transducer. The method of claim 3,
The plurality of slits may include a plurality of slits,
The linear slit and the refracting slit are formed adjacent to each other,
The refractive slit
A first linear portion, a first bend portion connected to the first straight portion, a second bend portion connected to the first bend portion, and a second straight portion connected to the second bend portion,
And an acoustic transducer. The method according to any one of claims 1 to 5,
The diaphragm includes:
A support portion extending downward from a bottom surface of the first depressed portion,
And an acoustic transducer. The method of claim 6,
The support portion
A plurality of support protrusions are provided so as to be spaced apart from each other by a predetermined distance,
And an acoustic transducer. The method of claim 6,
The support portion
A plurality of groups of fine protrusions are spaced apart from each other by a predetermined distance,
And an acoustic transducer. The method of claim 6,
The support portion
The substrate being spaced apart from the surface of the base substrate by a height of not less than 0.1 μm and not more than 10 μm,
And an acoustic transducer. The method according to claim 1,
The diaphragm includes:
A plurality of first depressed portions being spaced apart by a predetermined distance,
And an acoustic transducer. The method of claim 10,
The diaphragm includes:
A support portion extending downward from a bottom surface of the first depressed portion,
And an acoustic transducer. The method of claim 11,
The support portion
A plurality of support protrusions are provided so as to be spaced apart from each other by a predetermined distance,
And an acoustic transducer. The method of claim 11,
The support portion
A plurality of groups of fine protrusions are spaced apart from each other by a predetermined distance,
And an acoustic transducer. The method according to any one of claims 1, 2, 3, 4, 5 or 10,
The diaphragm includes:
Wherein a plurality of through holes passing through the back chamber of the base substrate are formed in a peripheral portion of the first depression. a first sacrificial layer 130 is formed by growing an insulating sacrificial material on the surface of the base substrate 100 at a first temperature by a depressurization type chemical vapor deposition method and forming a first sacrificial layer 130 on the surface of the first sacrificial layer 130, Growing a second sacrificial layer (140) by a pressure chemical vapor deposition method at a second high temperature;
b) wet-etching the second sacrificial layer 140 to form a first depression including a sidewall narrower from the second sacrificial layer 140 toward the first sacrificial layer 130;
c) forming a membrane layer 110 on the surface of the second sacrificial layer 140 having the first depression;
d) dry-etching the membrane layer (110) and a portion of the second sacrificial layer (140);
e) forming a membrane electrode at the center of the membrane layer (110), and forming a pad for bias voltage at the portion etched in step d);
f) forming an insulating sacrificial layer on the surface of the membrane layer 110 formed in step e) by chemical vapor deposition to form a third sacrificial layer 150, and forming an opposite electrode on the center of the third sacrificial layer 150 ;
g) wet etching the third sacrificial layer 150 formed in step f) to form a second depression including a sidewall narrower from the third sacrificial layer 150 toward the membrane layer 110 step;
h) wet etching the bottom surface of the second depression of the third sacrificial layer 150 formed in the step g) or the third sacrificial layer 150 around the second depression, depositing a silicon nitride film by chemical vapor deposition Forming a backplate membrane (120);
i) wet-etching the backplate membrane 120 formed in step h) to form a plurality of acoustic holes;
j) wet-etching the backplate 120 and a portion of the third sacrificial layer 150 to form a pad for the output voltage in the wet etched portion;
k) removing the first, second, and third sacrificial layers 130, 140, and 150 and the back surface of the base substrate 100 by wet etching to form a gap between the membrane layer 110 and the back plate membrane 120 Forming an air gap in the base substrate 100 and forming a back chamber in the base substrate 100;
Wherein the first and second acoustic transducers are connected to each other. 16. The method of claim 15,
Forming a support groove in the step b) by wet-etching the bottom surface of the first depression to the surface of the base substrate;
Further comprising the steps of: 16. The method of claim 15,
Forming a plurality of support grooves by selectively patterning and dry etching the bottom surface of the first depression to the surface of the base substrate in step b);
Further comprising the steps of: The method according to any one of claims 15 to 17,
Removing the membrane layer formed on the sidewall of the first depression to expose the second sacrificial layer 140 to form a plurality of slits;
Further comprising the steps of: 19. The method of claim 18,
The plurality of slits may include a plurality of slits,
The linear slit and the refracting slit are formed adjacent to each other,
The refractive slit
A first linear portion, a first bend portion connected to the first straight portion, a second bend portion connected to the first bend portion, and a second straight portion connected to the second bend portion,
Wherein the sound transmission device comprises: The method according to any one of claims 15 to 17,
In the step c), the second sacrificial layer 140 is exposed to the membrane layer to form a plurality of grooves.
Further comprising the steps of:

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