U.S. patent application number 15/373176 was filed with the patent office on 2018-03-15 for high sensitivity microphone and manufacturing method thereof.
The applicant listed for this patent is HYUNDAI MOTOR COMPANY. Invention is credited to Ilseon YOO.
Application Number | 20180077499 15/373176 |
Document ID | / |
Family ID | 60920362 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180077499 |
Kind Code |
A1 |
YOO; Ilseon |
March 15, 2018 |
HIGH SENSITIVITY MICROPHONE AND MANUFACTURING METHOD THEREOF
Abstract
A high sensitivity microphone includes a substrate having a
through portion provided in a central portion thereof, a vibration
membrane disposed on the substrate and covering the through
portion, a fixed membrane installed above the vibration membrane,
spaced apart from the vibration membrane with an air layer
interposed therebetween, and having a plurality of air inlets
perforated in a direction toward the air layer, and a plurality of
support posts provided as vertical elastic posts between the fixed
membrane and the vibration membrane and mechanically fixing the
vibration membrane by a frictional force, regardless of an applied
voltage.
Inventors: |
YOO; Ilseon; (Suwon-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HYUNDAI MOTOR COMPANY |
Seoul |
|
KR |
|
|
Family ID: |
60920362 |
Appl. No.: |
15/373176 |
Filed: |
December 8, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B81B 2201/0257 20130101;
B81C 2201/0109 20130101; H01L 51/0048 20130101; B81C 2201/013
20130101; H04R 31/00 20130101; H04R 31/003 20130101; H04R 19/04
20130101; H04R 2201/003 20130101; B81C 1/00158 20130101; B81B
3/0075 20130101; B81B 2203/0127 20130101; H04R 19/005 20130101 |
International
Class: |
H04R 19/04 20060101
H04R019/04; H04R 31/00 20060101 H04R031/00; B81B 3/00 20060101
B81B003/00; B81C 1/00 20060101 B81C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 9, 2016 |
KR |
10-2016-0116721 |
Claims
1. A high sensitivity microphone comprising: a substrate having a
through portion formed in a central portion of the substrate; a
vibration membrane disposed on the substrate and covering the
through portion; a fixed membrane disposed above the vibration
membrane, spaced apart from the vibration membrane with an air
layer interposed therebetween, and having a plurality of air inlets
perforated in a direction toward the air layer; and a plurality of
support posts disposed between the fixed membrane and the vibration
membrane, as elastic vertical posts, and mechanically fixing the
vibration membrane by a frictional force regardless of an applied
voltage.
2. The high sensitivity microphone of claim 1, wherein: the support
posts are formed of carbon nanotube (CNT) patterned between the
fixed membrane and the vibration membrane and arranged at a
predetermined interval in a circular shape from a central point of
the fixed membrane.
3. The high sensitivity microphone of claim 1, wherein: the support
posts serve as springs with rigidity deformed by a sound pressure
and are simultaneously deformed together with the vibration
membrane by a sound pressure.
4. The high sensitivity microphone of claim 1, wherein: the
vibration membrane has a free-floating membrane structure whose
contacts with respect to the support posts and the substrate are
not attached.
5. The high sensitivity microphone of claim 1, wherein: the
vibration membrane has a depression and protrusion portion formed
at edge on a bottom surface of the vibration membrane to prevent
attachment of the vibration membrane to the substrate.
6. The high sensitivity microphone of claim 1, wherein: the fixed
membrane includes a support portion that vertically extends from an
edge of the fixed membrane on the substrate.
7. The high sensitivity microphone of claim 1, wherein: the fixed
membrane has a fixed electrode disposed on a lower surface thereof
and perforated in the same pattern as that of the air inlets.
8. A method for manufacturing a high sensitivity microphone, the
method comprising: a) forming a first sacrificial layer on a
substrate and forming a vibration membrane thereon; b) forming a
second sacrificial layer on the vibration membrane and patterning
carbon nanotube (CNT) seeds on opposing sides of the second
sacrificial layer; c) forming a fixed membrane on the substrate
including the CNT seeds and the second sacrificial layer; d)
etching the fixed membrane to generate a plurality of perforated
air inlets; and e) removing the first sacrificial layer and the
second sacrificial layer and growing the CNT seeds to form a
plurality of CNT support posts as vertical elastic posts between
the fixed membrane and the vibration membrane to mechanically fix
the vibration membrane by a frictional force, regardless of an
applied voltage.
9. The method of claim 8, wherein operation a) comprises: etching a
portion of the first sacrificial layer to pattern a plurality of
recesses; and forming a depression and protrusion portion by the
plurality of recesses formed in the first sacrificial layer under
the vibration membrane.
10. The method of claim 8, wherein operation b) comprises:
patterning a fixed electrode in a central portion of the second
sacrificial layer.
11. The method of claim 10, wherein in operation d), the fixed
membrane and the fixed electrode are etched to generate a plurality
of air inlets perforated in the same pattern.
12. The high sensitivity microphone of claim 8, wherein operation
d) comprises: etching a rear side of the substrate to form a
through portion to which a sound pressure is input from the
outside.
13. The method of claim 8, wherein the vibration membrane includes
a monolayer membrane formed of polysilicon or a silicon nitride or
a multi-layer membrane formed by alternately stacking polysilicoin
and a silicon nitride.
14. The method of claim 8, wherein the first sacrificial layer and
the second sacrificial layer are formed of any one of a
photosensitive material, a silicon oxide, and a silicon
nitride.
15. The method of claim 8, wherein operation e) comprises: removing
the first sacrificial layer to position the vibration membrane in a
state of not being attached to the substrate; and fixing the
vibration membrane positioned in a non-attached manner on the
substrate by a frictional force of the CNT support posts.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 10-2016-0116721 filed in the Korean
Intellectual Property Office on Sep. 9, 2016, the entire content of
which is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a high sensitivity
microphone and a manufacturing method thereof.
BACKGROUND
[0003] In general, a microphone refers to a device converting a
sound such as a voice therearound into an electrical signal and
processing the electrical signal to a signal enabling a human being
or a machine finally to recognize the sound.
[0004] As microphones converting an audio signal into an electrical
signal, capacitive and piezoelectric type microphones have been
developed.
[0005] The capacitive type microphone includes a
micro-electrochemical system (MEMS) in which a fixed membrane and a
vibration membrane are spaced apart from each other. In the MEMS,
when a sound pressure is applied to the vibration membrane, a space
between the fixed membrane and the vibration membrane is changed to
cause a capacitive value to be changed to generate an electrical
signal, and the sound pressure is measured with the electrical
signal.
[0006] Compared with an existing electrets condenser microphone
(ECM), the capacitive type MEMS microphone is advantageous in that
performance thereof is less changed over a change in an external
environment such as a temperature or humidity and performance
variations of products are small due to a semiconductor batch
process.
[0007] Further, most capacitive type MEMS microphones have stable
frequency response characteristics and excellent sensitivity. In
the capacitive type microphone, a change in capacitance between a
vibration membrane and a fixed membrane is measured and output as a
voltage signal, and it is expressed as sensitivity, one of major
performance indices.
[0008] In order to enhance sensitivity, it is designed to lower
residual stress of a vibration membrane, and to this end, a
free-floating membrane structure has been researched.
[0009] FIG. 1 is a view illustrating a free-floating membrane
structure of a commercialized MEMS microphone according to a
related art.
[0010] Referring to FIG. 1, a general free-floating membrane
structure includes a vibration membrane 3, in a state of not being
fixed, between a substrate 1 and a fixed membrane 2, deviating from
a concept of an existing clamped capacitive type vibration
membrane.
[0011] With this structure, since the vibration membrane 3 is not
restrained between the substrate 1 and the fixed membrane 2 after
all the processes are finished, a vibration membrane residual
stress, one of the most important factors determining sensitivity
of the MEMS microphone, may be removed.
[0012] In the vibration membrane structure without a residual
stress, the vibration membrane 3 is fixed by electrostatic force
based on an applied voltage (i.e., a driving voltage) by applying a
rigid support post 4 to the free-floating membrane 3 and the fixed
membrane 2.
[0013] In detail, when a driving voltage (bias) is applied to the
microphone, the vibration membrane 3 is attracted toward the fixed
membrane 2 due to an electrostatic force and attached and fixed to
the support post 4 to vibrate by a sound pressure. When the driving
voltage is not applied, the vibration membrane 3 is separated from
the support post 4 and lowered to the substrate 1 because the
electrostatic force is released.
[0014] However, when the related art microphone is not driven, the
vibration membrane 3 is not fixed and free between the substrate 1
and the fixed membrane 2, and thus, the vibration membrane 3 may be
damaged due to an impact.
[0015] Stress caused as the vibration membrane 3 is repeatedly
brought into contact with or separated from the fixed membrane 2,
and the support post 4 according to driving/non-driving of the
microphone may degrade durability.
[0016] In addition, due to the clamped structure in which the
vibration membrane 3 is fixed to the rigid support post 4 when the
microphone is driven, it is not easy to adjust rigidity, making it
difficult to additionally enhance sensitivity.
[0017] Matters described in the background art section are provided
to promote understanding of the background of the present
disclosure, which may include a matter that is not a prior art
known to those skilled in the art to which the present disclosure
pertains.
SUMMARY
[0018] The present disclosure has been made in an effort to provide
a highly sensitive microphone having advantages of preventing an
impact regardless of an applied voltage by mechanically fixing a
vibration membrane through an elastic support post and increasing a
vibration displacement when a vibration membrane is vibrated by a
sound pressure by providing rigidity changed according to a sound
pressure, and a manufacturing method thereof.
[0019] According to an example embodiment of the present
disclosure, a high sensitivity microphone includes: a substrate
having a through portion provided in a central portion thereof; a
vibration membrane disposed on the substrate and covering the
through portion; a fixed membrane installed above the vibration
membrane, spaced apart from the vibration membrane with an air
layer interposed therebetween, and having a plurality of air inlets
perforated in a direction toward the air layer; and a plurality of
support posts provided as vertical elastic posts between the fixed
membrane and the vibration membrane and mechanically fixing the
vibration membrane by a frictional force, regardless of an applied
voltage.
[0020] The support posts may be formed of carbon nanotube (CNT)
patterned between the fixed membrane and the vibration membrane and
arranged at a predetermined interval in a circular shape from a
central point of the fixed membrane.
[0021] The support posts may serve as springs with rigidity
deformed by a sound pressure and may be simultaneously deformed
together with the vibration membrane by a sound pressure.
[0022] The vibration membrane may have a free-floating membrane
structure whose contacts with respect to the support posts and the
substrate are not attached.
[0023] The vibration membrane may have a depression and protrusion
portion provided on a lower edge thereof to prevent attachment of
the vibration membrane to the substrate.
[0024] A support portion of the fixed membrane vertically extending
from an edge thereof may be installed on the substrate.
[0025] The fixed membrane may have a fixed electrode disposed on a
lower surface thereof and perforated in the same pattern as that of
the air inlets.
[0026] According to another exemplary embodiment of the present
disclosure, a method for manufacturing a high sensitivity
microphone includes operations of: a) forming a first sacrificial
layer on a substrate and forming a vibration membrane thereon; b)
forming a second sacrificial layer on the vibration membrane and
patterning carbon nanotube (CNT) seeds on opposing sides of the
second sacrificial layer; c) forming a fixed membrane on the
substrate including the CNT seeds and the second sacrificial layer;
d) etching the fixed membrane to generate a plurality of perforated
air inlets; and e) removing the first sacrificial layer and the
second sacrificial layer and growing the CNT seeds to form a
plurality of CNT support posts as vertical elastic posts between
the fixed membrane and the vibration membrane to mechanically fix
the vibration membrane by a frictional force, regardless of an
applied voltage.
[0027] The operation a) may include: etching a portion of the first
sacrificial layer to pattern a plurality of recesses; and forming a
depression and protrusion portion by the plurality of recesses
formed in the first sacrificial layer under the vibration
membrane.
[0028] The operation b) may include: patterning a fixed electrode
in a central portion of the second sacrificial layer.
[0029] In the operation d), the fixed membrane and the fixed
electrode may be etched to generate a plurality of air inlets
perforated in the same pattern.
[0030] The operation d) may include etching a rear side of the
substrate to form a through portion to which a sound pressure is
input from the outside.
[0031] The vibration membrane may be formed as a monolayer membrane
using polysilicon or a silicon nitride or may be formed as a
multi-layer membrane by alternately stacking polysilicoin and a
silicon nitride.
[0032] The first sacrificial layer and the second sacrificial layer
may be formed of any one of a photosensitive material, a silicon
oxide, and a silicon nitride.
[0033] The operation e) may include: removing the first sacrificial
layer to position the vibration membrane in a state of not being
attached to the substrate; and fixing the vibration membrane
positioned in a non-attached manner on the substrate by a
frictional force of the CNT support posts.
[0034] According to the exemplary embodiment of the present
disclosure, since the patterned CNT support posts are formed
between the fixed membrane and the vibration membrane to
mechanically fix the vibration membrane by a frictional force of
the CNT support post, regardless of an applied voltage, an impact
applied to the vibration membrane may be prevented and durability
may be enhanced.
[0035] In addition, since the patterned CNT support posts serve as
springs with a structure having optimized rigidity to increase a
vibration displacement when the vibration membrane is vibrated by a
sound pressure, an effect of enhancing sensitivity may be
maximized.
[0036] In addition, application of high durability and high
sensitivity microphone according to an exemplary embodiment of the
present disclosure to a vehicle may enhance performance of
electronic equipment based on sound recognition, whereby
enhancement of customer satisfaction of products may be
anticipated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a view illustrating a free-floating membrane
structure of a related art commercialized micro-electrochemical
system (MEMS) microphone.
[0038] FIG. 2 is a schematic cross-sectional view of a microphone
according to an exemplary embodiment of the present disclosure.
[0039] FIG. 3 is a perspective view and a side view schematically
illustrating a fixed membrane, a vibration membrane, and a support
according to an exemplary embodiment of the present disclosure.
[0040] FIG. 4 is a cross-sectional view illustrating an operation
principle of a microphone when a sound pressure is input according
to an exemplary embodiment of the present disclosure.
[0041] FIG. 5 is a graph illustrating result of comparison and
verification of sensitivity between a microphone structure
according to an exemplary embodiment of the present disclosure and
a related art structure.
[0042] FIGS. 6 to 12 are views illustrating a method for
manufacturing a microphone according to an exemplary embodiment of
the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0043] In the following detailed description, only certain example
embodiments of the present disclosure have been shown and
described, simply by way of illustration. As those skilled in the
art would realize, the described embodiments may be modified in
various different ways, all without departing from the spirit or
scope of the present disclosure. Accordingly, the drawings and
description are to be regarded as illustrative in nature and not
restrictive. Like reference numerals designate like elements
throughout the specification.
[0044] Throughout the specification, unless explicitly described to
the contrary, the word "comprise" and variations such as
"comprises" or "comprising", will be understood to imply the
inclusion of stated elements but not the exclusion of any other
elements. In addition, the terms "-er", "-or" and "module"
described in the specification mean units for processing at least
one function and operation and can be implemented by hardware
components or software components and combinations thereof.
[0045] Hereinafter, a highly sensitive microphone and a
manufacturing method thereof according to exemplary embodiments of
the present disclosure will be described in detail with reference
to the accompanying drawings.
[0046] FIG. 2 is a schematic cross-sectional view of a microphone
according to an exemplary embodiment of the present disclosure.
[0047] FIG. 3 is a perspective view and a side view schematically
illustrating a fixed membrane, a vibration membrane, and a support
according to an exemplary embodiment of the present disclosure.
[0048] Referring to FIGS. 2 and 3, a microphone 100 according to an
exemplary embodiment of the present disclosure includes a substrate
110, a vibration membrane 120, a fixed membrane 130, and a carbon
nanotube (CNT) support post 140.
[0049] The substrate 110 may be formed of silicon and have a
through portion provided in a central portion thereof to which a
sound pressure is input.
[0050] The vibration membrane 120 covers the through portion 111 on
the substrate 110.
[0051] Thus, the vibration membrane 120 is partially exposed by the
through portion 111 formed in the substrate 110, and the exposed
portion of the vibration membrane 120 is vibrated by a sound
pressure transferred from the outside.
[0052] The vibration membrane 120 includes protrusion and
depression portions (dimples) 121 provided at a lower edge thereof
placed on the substrate in order to prevent attachment of the
vibration membrane 120 to the substrate 110. The protrusion and
depression portions 121 may have at least one protrusion.
[0053] The vibration membrane 120 may serve as an electrode by
itself, or may have a separate vibration electrode (not shown)
disposed in an upper portion thereof. Here, the vibration electrode
may be vibrated together with the vibration membrane 120 when a
sound pressure is input.
[0054] The vibration membrane 120 may have a monolayer membrane
structure formed of polysilicon or silicon nitride (SiNx) film.
Further, without being limited thereto, the vibration membrane 120
may have a multi-layer film structure in which polysilicon and
silicon nitride film are alternately stacked.
[0055] The fixed membrane 130 is installed above the vibration
membrane 120 and spaced apart from the vibration membrane 120 with
an air layer 131 interposed therebetween, and a support portion 134
vertically extending from the fixed membrane 130 is installed on
the substrate 110 in order to support the fixed membrane 130
(however, in order to show the CNT support post 140, the support
portion is omitted in FIG. 3).
[0056] Accordingly, the fixed membrane 130 has a casing structure
having a diameter greater than that of the vibration membrane 120
and covering the vibration membrane 120 placed on the substrate
110.
[0057] The fixed membrane 130 includes a plurality of air inlets
132 perforated in a direction toward the air layer 131.
[0058] A fixed electrode 133 is disposed on a lower portion of the
fixed membrane 130 and is perforated in the same pattern as that of
the air inlets 132.
[0059] That is, the fixed membrane 130 and the fixed electrode 133
include a plurality of air inlets 132 perforated in the same
pattern. Here, since the plurality of air inlets 132 allow for an
air flow, the fixed membrane 130 and the fixed electrode 133 are
not vibrated by a sound source.
[0060] The CNT support post 140 is formed as a vertical elastic
post between the fixed membrane 130 and the vibration membrane 120,
and mechanically fixes the vibration membrane 120, regardless of an
applied voltage.
[0061] The CNT support post 140, a carbon nanotube (CNT) patterned
between the fixed membrane 130 and the vibration membrane 120,
mechanically fixes the vibration membrane 120 by a frictional
force.
[0062] The CNT support posts 140 are arranged at a uniform interval
in a circular shape based on a central point of the fixed membrane
130.
[0063] The CNT support post 140 may be able to fix the vibration
membrane 120, regardless of an applied voltage (i.e.,
driving/non-driving) in the related art, by growing a CNT seed
formed on a lower portion of the fixed membrane 130 and applying a
frictional force to an upper portion of the vibration membrane 120
through a follow-up process in manufacturing a
micro-electrochemical system (MEMS).
[0064] Here, the vibration membrane 120 may have a free-floating
membrane structure in which the vibration membrane 120 is fixed by
a frictional force between the CNT support posts 140 but a contact
point with respect to the CNT support post 140 or the substrate 110
is not mechanically or chemically attached.
[0065] That is, in the related art, the free-floating membrane is
not fixed so it is damaged by an impact in a non-driving state
without an applied voltage.
[0066] In contrast, in an exemplary embodiment of the present
disclosure, even in a non-driving state without an applied voltage,
the vibration membrane 120 is fixed mechanically by a frictional
force of the CNT support post 14, whereby the damage problem is
solved and high durability is provided.
[0067] FIG. 4 is a cross-sectional view illustrating an operation
principle of a microphone when a sound pressure is input according
to an exemplary embodiment of the present disclosure.
[0068] Referring to FIG. 4, a CNT support post 140 according to an
exemplary embodiment of the present disclosure serves as a spring
through adjustment of rigidity of a columnar CNT, and for the
purposes of description, the CNT support post 140 is illustrated as
a spring.
[0069] The vibration membrane 120 is fixed to the substrate 110 by
the CNT support post 140 and horizontally disposed in a non-driving
state.
[0070] When a sound pressure is input in a driving state, the
vibration membrane 120 is vibrated by the sound pressure, causing a
space between the vibration membrane 120 and the fixed membrane 130
to be changed, and thus, capacitance between the vibration membrane
120 and the fixed membrane 130 is changed.
[0071] In particular, the CNT support 140 is deformed by the sound
pressure together with the vibration membrane 120 to increase a
vibration displacement of the vibration membrane 120.
[0072] That is, a displacement due to the role of the CNT support
post 140 as a spring is added to a displacement of the vibration
membrane 120 due to the sound pressure to increase an overall
vibration displacement, whereby a vibration width between the
vibration membrane 120 and the fixed membrane 130 is increased to
increase a change in capacitance.
[0073] The increased capacitance is transferred through a pad (not
shown) and a conducting wire connected to each of the fixed
electrode 133 and the vibration membrane 120 and converted into an
electrical signal by a circuit (not shown) for signal processing to
sense a sound from the outside, thereby implementing a high
sensitivity microphone 100.
[0074] FIG. 5 is a graph illustrating result of comparison and
verification of sensitivity between a microphone structure
according to an exemplary embodiment of the present disclosure and
a related art structure.
[0075] Referring to FIG. 5, the related art support post 4 as
illustrated in FIG. 1 merely serves as a fixed end as a rigidity
structure, which is not easy to adjust rigidity thereof, leading to
a difficulty in additionally enhancing sensitivity.
[0076] In contrast, the CNT support post 140 according to an
exemplary embodiment of the present disclosure serves as a spring
with elasticity simultaneously deformed with the vibration membrane
120 by a sound pressure, further increasing vibration displacement
when the vibration membrane 120 is vibrated by a sound pressure,
thus resultantly obtaining enhancement of sensitivity.
[0077] A method for manufacturing the high sensitivity microphone
100 according to an exemplary embodiment of the present disclosure
will be described with reference to the accompanying drawings.
[0078] FIGS. 6 to 12 are views illustrating a method for
manufacturing a microphone according to an exemplary embodiment of
the present disclosure.
[0079] Referring to FIG. 6, after a substrate 110 is prepared, a
first sacrificial layer 150-1 is formed on the substrate 110 and
partially etched to pattern a recess 151 for formation of a
depression and protrusion portion 121 of a vibration membrane 120.
Here, the substrate 110 may be formed of silicon.
[0080] The first sacrificial layer 150-1 may be formed of any one
of a photosensitive material, a silicon oxide, and a silicon
nitride. The photosensitive material may have a thermally and
mechanically stable structure and may be easily removed in terms of
process.
[0081] Referring to FIG. 7, the vibration membrane 120 is formed on
an upper portion of the first sacrificial layer 150-1.
[0082] Here, a depression and protrusion portion 121 is formed
under the vibration membrane 120 along the recess 151 formed on the
first sacrificial layer 150-1.
[0083] Here, the vibration membrane 120 may be formed as a
monolayer membrane using polysilicoin or a silicon nitride film.
Without being limited thereto, the vibration membrane 120 may also
be formed as a multi-layer by alternately stacking polysilicon and
a silicon nitride film.
[0084] Referring to FIG. 8, a second sacrificial layer 150-2 is
formed on the vibration membrane 120 and the first sacrificial
layer 150-1. Here, the second sacrificial layer 150-2 may be formed
of the same material as that of the first sacrificial layer 150-1
and may have a thickness for forming an air layer 131.
[0085] Referring to FIG. 9, a CNT (seed metal) 141 for growing a
CNT support post 140 later is patterned on both side portions of
the second sacrificial layer 150-2, and a fixed electrode 133
formed under a fixed membrane 130 later is patterned in a central
portion of the second sacrificial layer 150-2. Here, the fixed
electrode 133 may be patterned by a polysilicon.
[0086] Referring to FIG. 10, the fixed membrane 130 is formed on
the substrate 100 including the CNT seed 141, the fixed electrode
133, and the second sacrificial layer 150-2.
[0087] The fixed membrane 130 may have a "U" shape and cover the
entire area of the substrate 110.
[0088] Here, the fixed membrane 130 may be formed by depositing a
silicon nitride (SiN). In another exemplary embodiment, the fixed
membrane 130 may be formed by depositing polysilicon.
[0089] Thereafter, the fixed membrane 130 and the fixed electrode
133 positioned thereunder are etched to generate a plurality of air
inlets 132 perforated in the same pattern.
[0090] Here, the plurality of air inlets 132 may be formed through
dry etching or wet etching, and etching is performed until the
second sacrificial layer 150-2 is exposed in a vertical direction
in which the vibration membrane 120 is formed.
[0091] In addition, a rear surface of the substrate 110 is etched
until the first sacrificial layer 150-1 is exposed to form a
through portion 111 to which a sound pressure is input from the
outside.
[0092] Referring to FIG. 11, the second sacrificial layer 150-2 and
the first sacrificial layer 150-1 are removed to form an air layer
131 between the vibration membrane 120 and the fixed membrane
130.
[0093] The sacrificial layers 150 may be removed through a wet
etching method using an etchant through the air inlet 132. Also,
the sacrificial layers 150 may be removed through a dry etching
method by performing ashing based on oxygen (O.sub.2) plasma
through the air inlet 132.
[0094] When the sacrificial layers 150 are removed through the wet
or dry etching method, the air layer 131 is formed and the
vibration membrane 120 is placed in a non-attached state on the
substrate 110.
[0095] Referring to FIG. 12, when the sacrificial layers are
entirely removed, the CNT seed 141 is grown to form the CNT support
post 140.
[0096] Columnar end portions of the plurality of CNT support posts
140 are lowered to be in contact with upper portions of the
vibration membrane 120 positioned not to be attached to the
substrate 110, thereby mechanically fixing the vibration membrane
120 by a frictional force.
[0097] Thereafter, although not shown, the fixed electrode 133 of
the fixed membrane 130 and a vibration electrode of the vibration
membrane 120 may be electrically connected to a circuit for signal
processing through a pad and a conducting wire thereof.
[0098] The microphone and the manufacturing method thereof
according to exemplary embodiments of the present disclosure
described above are not limited to the aforementioned process
(flow) but may be variously modified.
[0099] For example, in FIG. 10, it is illustrated and described
that the plurality of air inlets 132 are formed, and thereafter,
the through portion 111 is formed on a rear side of the substrate
110, but the manufacturing method of the present disclosure is not
limited to the order of the description. For example, the process
of forming the through hole 111 on the rear side of the substrate
110 may also be performed before the formation of the air inlets
132 or after the sacrificial layers 150 of FIG. 11 are removed.
[0100] In this manner, according to an exemplary embodiment of the
present disclosure, since the patterned CNT support posts are
formed between the fixed membrane and the vibration membrane to
mechanically fix the vibration membrane by a frictional force of
the CNT support post, regardless of an applied voltage, an impact
applied to the vibration membrane may be prevented and durability
may be enhanced.
[0101] Since the patterned CNT support posts serve as springs with
a structure having optimized rigidity to increase vibration
displacement when the vibration membrane is vibrated by a sound
pressure, an effect of enhancing sensitivity may be maximized.
[0102] In addition, application of high durability and high
sensitivity microphone according to an exemplary embodiment of the
present disclosure to a vehicle may enhance performance of
electronic equipment based on sound recognition, whereby
enhancement of customer satisfaction of products may be
anticipated.
[0103] The exemplary embodiments of the present disclosure may not
necessarily be implemented only through the foregoing devices
and/or methods but may also be implemented through a program for
realizing functions corresponding to the configurations of the
embodiments of the present disclosure, a recording medium including
the program, or the like, and such an implementation may be easily
made by a skilled person in the art to which the present disclosure
pertains from the foregoing description of the embodiments.
[0104] While this invention has been described in connection with
what is presently considered to be practical example embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
* * * * *