U.S. patent application number 16/025074 was filed with the patent office on 2019-07-11 for mems microphone with tunable sensitivity.
The applicant listed for this patent is Fortemedia, Inc.. Invention is credited to Jien-Ming CHEN, Nai-Hao KUO, Hsin-Li LEE, Wen-Shan LIN.
Application Number | 20190210866 16/025074 |
Document ID | / |
Family ID | 67106244 |
Filed Date | 2019-07-11 |
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United States Patent
Application |
20190210866 |
Kind Code |
A1 |
CHEN; Jien-Ming ; et
al. |
July 11, 2019 |
MEMS MICROPHONE WITH TUNABLE SENSITIVITY
Abstract
A micro-electro-mechanical system (MEMS) microphone is provided.
The MEMS microphone includes a substrate, a backplate, a diaphragm,
a first insulating protrusion and a plurality of second insulating
protrusions. The backplate is disposed on a side of the substrate.
The diaphragm is disposed between the substrate and the backplate
and is movable relative to the backplate. The first insulating
protrusion and the second insulating protrusions are formed on the
side of the backplate facing the diaphragm. The first insulating
protrusion is connected to and affixed to the diaphragm
permanently, and an air gap is formed between the diaphragm and
each of the second insulating protrusions.
Inventors: |
CHEN; Jien-Ming; (Tainan
City, TW) ; KUO; Nai-Hao; (Tainan City, TW) ;
LIN; Wen-Shan; (Tainan City, TW) ; LEE; Hsin-Li;
(Tainan City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fortemedia, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
67106244 |
Appl. No.: |
16/025074 |
Filed: |
July 2, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62614552 |
Jan 8, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B81B 2203/0127 20130101;
B81B 2201/0257 20130101; H04R 7/24 20130101; H04R 19/005 20130101;
B81B 7/02 20130101; H04R 7/08 20130101; H04R 19/04 20130101; B81C
1/00182 20130101; H04R 2201/003 20130101; B81B 3/0072 20130101 |
International
Class: |
B81B 7/02 20060101
B81B007/02; H04R 19/04 20060101 H04R019/04; H04R 19/00 20060101
H04R019/00; H04R 7/08 20060101 H04R007/08 |
Claims
1. A micro-electro-mechanical system (MEMS) microphone, comprising:
a substrate; a backplate disposed on a side of the substrate; a
diaphragm disposed between the substrate and the backplate and
movable relative to the backplate; and a first insulating
protrusion and a plurality of second insulating protrusions
extending from a first side of the backplate facing the diaphragm,
wherein the first insulating protrusion is fixedly connected to the
diaphragm, and an air gap is formed between the diaphragm and each
of the second insulating protrusions; wherein the diaphragm
includes a plurality of long apertures arranged in concentric
circles and configured to adjust a stiffness of the diaphragm,
wherein each of the long apertures communicates with an upper
surface and a lower surface of the diaphragm, and the long
apertures of adjacent circles are arranged in a staggered
manner.
2. The MEMS microphone as claimed in claim 1, wherein the first
insulating protrusion is located in a center region of the
diaphragm, and the second insulating protrusions are located in an
annular region of the diaphragm surrounding the center region.
3. The MEMS microphone as claimed in claim 2, wherein the second
insulating protrusions are annular protrusions arranged in
concentric circles.
4. The MEMS microphone as claimed in claim 3, wherein a protrusion
height of the second insulating protrusions gradually decreases
from a location where the second insulating protrusion is close to
the center region of the diaphragm to a location where the second
insulating protrusion is close to an outer edge of the annular
region of the diaphragm.
5. The MEMS microphone as claimed in claim 2, wherein the second
insulating protrusions are individual island-shaped protrusions
arranged in concentric circles.
6. The MEMS microphone as claimed in claim 5, wherein a protrusion
height of the second insulating protrusions gradually decreases
from a location where the second insulating protrusion is close to
the center region of the diaphragm to a location where the second
insulating protrusion is close to an outer edge of the annular
region of the diaphragm.
7. (canceled)
8. The MEMS microphone as claimed in claim 1, further comprising a
dielectric layer disposed between the substrate and the diaphragm
and between the diaphragm and the backplate, configured to clamp a
peripheral portion of the diaphragm, and the long apertures of the
diaphragm are located close to the dielectric layer.
9. The MEMS microphone as claimed in claim 1, wherein the diaphragm
includes at least one vent hole configured to allow sound waves to
pass through.
10. The MEMS microphone as claimed in claim 1, wherein the
diaphragm includes at least one vent valve configured to allow
sound waves to pass through, and the at least one vent valve has an
open area that is variable in response to a change in acoustic
pressure of the sound waves passing through the at least one vent
valve.
11. The MEMS microphone as claimed in claim 1, wherein the
diaphragm includes at least one vent hole and at least one vent
valve configured to allow sound waves to pass through, and the at
least one vent valve has an open area that is variable in response
to a change in acoustic pressure of the sound waves passing through
the at least one vent valve.
12. The MEMS microphone as claimed in claim 1, wherein the
backplate has a recess formed on a second side of the backplate
opposite to the first side and corresponding to the first
insulating protrusion, and a protection layer is provided to cover
the recess.
13. The MEMS microphone as claimed in claim 12, wherein the
protection layer comprises conductive material.
14. The MEMS microphone as claimed in claim 1, wherein the first
insulating protrusion is a solid column connecting the backplate
and a center of the diaphragm.
15. The MEMS microphone as claimed in claim 1, wherein the first
insulating protrusion is a hollow column connecting the backplate
and a center of the diaphragm.
16. The MEMS microphone as claimed in claim 15, wherein the
diaphragm includes a vent hole having a fixed open area configured
to allow sound waves to pass through, and the vent hole is aligned
with a hollow portion of the hollow column.
17. The MEMS microphone as claimed in claim 15, wherein the
diaphragm includes a vent valve having a variable open area
configured to allow sound waves to pass through, and the vent valve
is aligned with a hollow portion of the hollow column.
18. The MEMS microphone as claimed in claim 1, wherein the
backplate includes a conductive layer and an insulating layer
covering the conductive layer, and the conductive layer and the
insulating layer are respectively located on the first side and a
second side of the backplate opposite to the first side, and
wherein the first insulating protrusion and the second insulating
protrusions are integrally formed with the insulating layer and
protrude toward the diaphragm.
19. The MEMS microphone as claimed in claim 18, wherein the
insulating layer of the backplate includes a first insulating layer
and a second insulating layer stacked on the first insulating
layer.
20. The MEMS microphone as claimed in claim 1, further comprising
an additional insulating layer connected between the first
insulating protrusion and the diaphragm.
21. A micro-electro-mechanical system (MEMS) microphone,
comprising: a substrate; a backplate disposed on a side of the
substrate; a diaphragm disposed between the substrate and the
backplate and movable relative to the backplate; and a first
insulating protrusion and a plurality of second insulating
protrusions extending from a first side of the backplate facing the
diaphragm, wherein the first insulating protrusion is fixedly
connected to the diaphragm, and an air gap is formed between the
diaphragm and each of the second insulating protrusions; wherein
the backplate has a recess formed on a second side of the backplate
opposite to the first side and corresponding to the first
insulating protrusion, and a protection layer is filled into the
recess.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority of U.S. Provisional
Patent Application No. 62/614,552, filed on Jan. 8, 2018, the
entirety of which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The invention relates to an acoustic transducer, and more
particularly to a micro-electro-mechanical system (MEMS)
microphone.
Description of the Related Art
[0003] The current tendency is toward fabricating slim, compact,
lightweight and high-performance electronic devices, including
microphones. A microphone is used to receive sound waves and
convert acoustic signal into electric signal. Microphones are
widely used in daily life and are installed in such electronic
products as telephones, mobiles phones, and recording pens. In a
capacitive microphone, the variation of acoustic pressure (i.e.
local pressure deviation from the ambient atmospheric pressure
caused by sound waves) forces the diaphragm to deform
correspondingly, and the deformation of the diaphragm induces a
capacitance variation. The variation of acoustic pressure of the
sound waves can thus be obtained by detecting the voltage
difference caused by the capacitance variation.
[0004] This is distinct from the conventional electret condenser
microphones (ECM), in which mechanical and electronic elements of
micro-electro-mechanical system (MEMS) microphones can be
integrated on a semiconductor material using integrated circuit
(IC) technology to fabricate a miniaturized microphone. MEMS
microphones have advantages such as a compact size, being
lightweight, and having low power consumption, and they have
therefore entered the mainstream of miniaturized microphones.
[0005] Although existing MEMS microphones have generally been
adequate for their intended purposes, they have not been entirely
satisfactory in all respects. For example, the compatible acoustic
pressure range (i.e. dynamic range) of detectable sound waves in a
MEMS microphone still needs improvement. The dynamic range is
related to the highest compatible acoustic pressure (i.e. acoustic
overload point, which is referred to hereinafter as the "AOP"),
which is determined by the harmonic distortion rate (total harmonic
distortion, which is referred to hereinafter as the "THD") of the
MEMS microphone. On the other hand, if the diaphragm has a lower
elastic modulus (i.e. lower stiffness), it can be used to sense a
smaller acoustic pressure (i.e. have higher sensitivity), but the
THD of the diaphragm will be sacrificed accordingly (i.e. the AOP
will be reduced). Therefore, it cannot achieve high AOP and high
sensitivity, simultaneously, of a MEMS microphone (i.e. unable to
achieve a wider dynamic range).
BRIEF SUMMARY OF THE INVENTION
[0006] In view of the aforementioned problems, an object of the
invention is to provide a MEMS microphone that can achieve high AOP
and high sensitivity simultaneously.
[0007] An embodiment of the invention provides a MEMS microphone.
The MEMS microphone includes a substrate, a backplate, a diaphragm,
a first insulating protrusion and a plurality of second insulating
protrusions. The backplate is disposed on a side of the substrate.
The diaphragm is disposed between the substrate and the backplate
and is movable relative to the backplate. The first insulating
protrusion and the second insulating protrusions are formed on the
side of the backplate facing the diaphragm. The first insulating
protrusion is connected to and affixed to the diaphragm
permanently, and an air gap is formed between the diaphragm and
each of the second insulating protrusions.
[0008] In some embodiments, the first insulating protrusion is
located in a center region of the diaphragm, and the second
insulating protrusions are located in an annular region of the
diaphragm surrounding the center region.
[0009] In some embodiments, the second insulating protrusions are
annular protrusions arranged in concentric circles.
[0010] In some embodiments, the protrusion height of the second
insulating protrusions gradually decreases from a location where
the second insulating protrusion is close to the center region of
the diaphragm to a location where the second insulating protrusion
is close to an outer edge of the annular region of the
diaphragm.
[0011] In some embodiments, the second insulating protrusions are
individual island-shaped protrusions arranged in concentric
circles.
[0012] In some embodiments, the diaphragm includes a plurality of
long apertures arranged in concentric circles, the long apertures
of adjacent circles being arranged alternately, configured to
adjust the stiffness of the diaphragm.
[0013] In some embodiments, the MEMS microphone further includes a
dielectric layer disposed between the substrate and the diaphragm
and between the diaphragm and the backplate, configured to clamp a
peripheral portion of the diaphragm. The long apertures of the
diaphragm are located close to the dielectric layer.
[0014] In some embodiments, the diaphragm includes at least one
vent hole configured to allow sound waves to pass through.
[0015] In some embodiments, the diaphragm includes at least one
vent valve configured to allow sound waves to pass through. The
vent valve has an open area that is variable in response to a
change in acoustic pressure of the sound waves passing through the
vent valve.
[0016] In some embodiments, the diaphragm includes at least one
vent hole and at least one vent valve configured to allow sound
waves to pass through. The vent valve has an open area that is
variable in response to a change in acoustic pressure of the sound
waves passing through the vent valve.
[0017] In some embodiments, the backplate has a recess formed on a
second side of the backplate opposite to the first side and
corresponding to the first insulating protrusion. A protection
layer is provided to cover the recess.
[0018] In some embodiments, the protection layer comprises
conductive material.
[0019] In some embodiments, the first insulating protrusion is a
solid column connecting the backplate and the center of the
diaphragm.
[0020] In some embodiments, the first insulating protrusion is a
hollow column connecting the backplate and the center of the
diaphragm.
[0021] In some embodiments, the diaphragm includes a vent hole
having a fixed open area configured to allow sound waves to pass
through. The vent hole is aligned with a hollow portion of the
hollow column.
[0022] In some embodiments, the diaphragm includes a vent valve
having a variable open area configured to allow sound waves to pass
through. The vent valve is aligned with a hollow portion of the
hollow column.
[0023] In some embodiments, the backplate includes a conductive
layer and an insulating layer covering the conductive layer. The
conductive layer and the insulating layer are respectively located
on the first side and a second side of the backplate opposite to
the first side. The first insulating protrusion and the second
insulating protrusions are integrally formed with the insulating
layer and protrude toward the diaphragm.
[0024] In some embodiments, the insulating layer of the backplate
includes a first insulating layer and a second insulating layer
stacked on the first insulating layer.
[0025] In some embodiments, the MEMS microphone further includes an
additional insulating layer connected between the first insulating
protrusion and the diaphragm.
[0026] In order to illustrate the purposes, features, and
advantages of the invention, the preferred embodiments and drawings
of the invention are shown in detail as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The invention can be more fully understood by reading the
subsequent detailed description and examples with references made
to the accompanying drawings, wherein:
[0028] FIG. 1 schematically illustrates a cross-sectional view of a
MEMS microphone, in accordance with some embodiments.
[0029] FIG. 2A schematically illustrates the arrangement of the
diaphragm, the first insulating protrusion and the second
insulating protrusions in FIG. 1 from another viewing angle, in
accordance with some embodiments.
[0030] FIG. 2B schematically illustrates the arrangement of the
diaphragm, the first insulating protrusion and the second
insulating protrusions in FIG. 1 from another viewing angle, in
accordance with some embodiments.
[0031] FIG. 3 schematically illustrates a cross-sectional view of a
MEMS microphone, in accordance with some embodiments.
[0032] FIG. 4 schematically illustrates a cross-sectional view of a
MEMS microphone, in accordance with some embodiments.
[0033] FIG. 5 schematically illustrates the arrangement of the vent
holes in the diaphragm in FIG. 4 from another viewing angle, in
accordance with some embodiments.
[0034] FIG. 6 schematically illustrates a cross-sectional view of a
MEMS microphone, in accordance with some embodiments.
[0035] FIG. 7A schematically illustrates the shape of the vent
valve in the diaphragm in FIG. 5 from another viewing angle, in
accordance with some embodiments.
[0036] FIG. 7B schematically illustrates the shape of the vent
valve in the diaphragm in FIG. 5 from another viewing angle, in
accordance with some embodiments.
[0037] FIG. 7C schematically illustrates the shape of the vent
valve in the diaphragm in FIG. 5 from another viewing angle, in
accordance with some embodiments.
[0038] FIG. 8 schematically illustrates a cross-sectional view of a
MEMS microphone, in accordance with some embodiments.
[0039] FIG. 9 schematically illustrates a cross-sectional view of a
MEMS microphone, in accordance with some embodiments.
[0040] FIG. 10 schematically illustrates a cross-sectional view of
a MEMS microphone, in accordance with some embodiments.
DETAILED DESCRIPTION OF THE INVENTION
[0041] The following description is of the best-contemplated mode
of carrying out the invention. This description is made for the
purpose of illustrating the general principles of the invention and
should not be taken in a limiting sense. The scope of the invention
is best determined by reference to the appended claims.
[0042] In the following detailed description, the orientations of
"on", "above", "under", and "below" are used for representing the
relationship between the relative positions of each element as
illustrated in the drawings, and are not meant to limit the
invention. Moreover, the formation of a first element on or above a
second element in the description that follows may include
embodiments in which the first and second elements are formed in
direct contact, or the first and second elements have one or more
additional elements formed therebetween.
[0043] In addition, the present disclosure may repeat reference
numerals and/or letters in the various examples. This repetition is
for the purpose of simplicity and clarity and does not in itself
dictate a relationship between the various embodiments and/or
configurations discussed. Various features may be arbitrarily drawn
in different scales for the sake of simplicity and clarity.
Furthermore, some elements not shown or described in the
embodiments have the forms known by persons skilled in the field of
the invention.
[0044] In the present disclosure, a micro-electro-mechanical system
(MEMS) microphone for detecting sound waves and converting the
sound waves (acoustic signal) into electric signal is provided, in
accordance with various exemplary embodiments. In particular, the
MEMS microphones in the various embodiments can achieve high AOP
(i.e. achieve a wider dynamic range) and high sensitivity
simultaneously via the following described features. The variations
of some embodiments are discussed. Throughout the various views and
illustrative embodiments, like reference numbers are used to
designate like elements.
[0045] FIG. 1 schematically illustrates a cross-sectional view of a
MEMS microphone M, in accordance with some embodiments. It should
be noted that the MEMS microphone M depicted in FIG. 1 has been
simplified for the sake of clarity to better understand the
inventive concepts of the present disclosure. Additional features
can be added into the MEMS microphone M, and some of the features
described below can be replaced or eliminated in other embodiments
of the MEMS microphone M. As shown in FIG. 1, the MEMS microphone M
which is a capacitive microphone includes a MEMS structure 10
including a substrate 11, a dielectric layer 12, a backplate 13, a
diaphragm 14, and an electrode layer 15.
[0046] The substrate 11 is configured to support the dielectric
layer 12, the backplate 13, the diaphragm 14, and the electrode
layer 15 on a side thereof. The substrate 11 may have an opening
portion 11A which allows sound waves (e.g., as the arrow indicated
in FIG. 1) received by the MEMS microphone M to pass through and/or
enter the MEMS structure 10. The substrate 11 may be made of
silicon or the like.
[0047] The dielectric layer 12 is disposed between the substrate 11
and the diaphragm 14, and between the diaphragm 14 and the
backplate 13, so as to provide partial isolation between the
substrate 11, the diaphragm 14, and the backplate 13 from each
other. Moreover, the dielectric layer 12 is disposed around the
backplate 13 and the diaphragm 14, such that the backplate 13 and
the diaphragm 14 are clamped at their edges by the dielectric layer
12. Furthermore, the dielectric layer 12 may have an opening
portion 12A corresponding to the opening portion 11A of the
substrate 11, so as to allow the sound waves to pass through the
diaphragm 14 and the backplate 13 and then leave the MEMS structure
10. The dielectric layer 12 may be made of silicon oxide or the
like.
[0048] The backplate 13 is a stationary element disposed on a side
of the substrate 11. The backplate 13 may have sufficient stiffness
such that it would not be bent or movable when the sound waves pass
through the backplate 13. In some embodiments, the backplate 13 is
a stiff perforated element including a number of acoustic holes 13A
each passing through the backplate 13, as shown in FIG. 1. The
acoustic holes 13A are configured to allow the sound waves to pass
through.
[0049] In some embodiments, the backplate 13 includes a conductive
layer 131 and an insulating layer 132 covering the conductive layer
131 for protection, as shown in FIG. 1. The conductive layer 131
and the insulating layer 132 are respectively located on a first
side Si of the backplate 13 facing the diaphragm 14 and a second
side S2 of the backplate 13 opposite to the first side S1. The
conductive layer 131 may be made of poly-silicon or the like, and
the insulating layer 132 may be made of silicon nitride or the
like.
[0050] In some embodiments, the MEMS structure 10 is electrically
connected to a circuit (not shown) via several electrode pads of
the electrode layer 15 that is disposed on the backplate 13 and
electrically connected to the conductive layer 131 and the
diaphragm 14. In some embodiments, the electrode layer 15 comprises
copper, silver, gold, aluminum, or alloy thereof.
[0051] The diaphragm 14 is movable or displaceable relative to the
backplate 13. The diaphragm 14 is configured to sense the sound
waves received by the MEMS microphone M.
[0052] The displacement change of the diaphragm 14 relative to the
backplate 13 causes a capacitance change between the diaphragm 14
and the backplate 13. The capacitance change is then converted into
an electric signal by a circuitry connected with the diaphragm 14
and the backplate 13, and the electrical signal is sent out of the
MEMS microphone M through the electrode layer 15.
[0053] In some embodiments, a first insulating protrusion 133 is
provided or formed on the first side Si of the backplate 13 facing
the diaphragm 14, and the first insulating protrusion 133 is
connected to and affixed to the diaphragm 14 permanently, as shown
in FIG. 1. In some embodiments, the first insulating protrusion 133
is integrally formed with the insulating layer 132 and protrudes
toward the diaphragm 14. The first insulating protrusion 133 may be
a solid column connecting the backplate 13 and (e.g. the center of)
the diaphragm 14, so that the first insulating protrusion 133
supports the diaphragm 14 to increase stiffness of the diaphragm
14, thereby increasing the AOP of the MEMS Microphone M.
[0054] In some embodiments, an additional insulating layer 17 is
also provided and connected between the first insulating protrusion
133 and the diaphragm 14, as shown in FIG. 1. The additional
insulating layer 17 may include the same material as the dielectric
layer 12 or another insulating material. However, the additional
insulating layer 17 can be omitted in different embodiments.
[0055] On the other hand, in order to increase the sensitivity of
the diaphragm 14, a number of long apertures 141 may be provided in
the diaphragm 14. In some embodiments, the long apertures 141 in
the diaphragm 14 are arranged in concentric circles close to the
dielectric layer 12 (e.g., between the conductive layer 131 of the
backplate 13 and the dielectric layer 12) and the long apertures of
adjacent circles are arranged alternately (see FIGS. 1 and 2A), so
that the long apertures 141 can serve as a spring in the diaphragm
14 to reduce the stiffness of the diaphragm 14. In some alternative
embodiments, the number of concentric circles formed by the long
apertures 141 may be more than two. With this structural feature,
high sensitivity of the MEMS microphone M can be achieved.
[0056] In addition, the long apertures 141 in the diaphragm 14 are
also configured to relieve the stress on the diaphragm 14.
[0057] In some embodiments, a number of second insulating
protrusions 134 are also provided or formed on the first side 51 of
the backplate 13, and an air gap G is formed between the diaphragm
14 and each of the second insulating protrusions 134, as shown in
FIG. 1. In addition, the air gap G between the diaphragm 14 and
each of the second insulating protrusions 134 may be the same (but
not limited thereto).
[0058] FIGS. 2A and 2B schematically illustrate the arrangement of
the diaphragm 14, the first insulating protrusion 133 and the
second insulating protrusions 134 in FIG. 1 from another viewing
angle, in accordance with some embodiments. As shown, the first
insulating protrusion 133 may be located in a center region R1 of
the circular diaphragm 14, and the second insulating protrusions
may be located in an annular region R2 of the diaphragm 14
surrounding the center region R1. In addition, the second
insulating protrusions 134 may be annular protrusions arranged in
concentric circles (FIG. 2A), or the second insulating protrusions
134 may be individual island-shaped protrusions arranged in
concentric circles (FIG. 2B). However, it should be appreciated
that many variations and modifications can be made to the
embodiments of the disclosure.
[0059] Referring to FIG. 1, to form the first insulating protrusion
133 and the second insulating protrusions 134, the insulating layer
132 of the backplate 13 may include a first insulating layer 1321
and a second insulating layer 1322 stacked on the first insulating
layer 1321. In some embodiments, the first and second insulating
layers 1321 and 1322 may comprise the same material or different
material. In some embodiments, a protection layer 16 is provided to
cover a recess D that is formed on the second side S2 and
corresponding to the first insulating protrusion. The protection
layer 16 may comprise conductive material (e.g., aluminum) or
another material.
[0060] FIG. 3 schematically illustrates a cross-sectional view of a
MEMS microphone M, in accordance with some other embodiments. The
MEMS microphone M in FIG. 3 differs from the embodiments of the
MEMS microphone M in FIGS. 1, 2A and 2B in that the protrusion
height of the second insulating protrusions 134 (may be annular
protrusions or individual island-shaped protrusions) gradually
decreases from the location where the second insulating protrusion
134 is close to the center region R1 (FIGS. 2A and 2B) of the
diaphragm 14 to the location where the second insulating protrusion
134 is close to the outer edge of the annular region R2 (FIGS. 2A
and 2B) of the diaphragm 14.
[0061] With these structural features, when a predetermined voltage
is applied via the electrode layer 15, the conductive layer 131 of
the backplate 13 and the diaphragm 14 would close to each other.
More specifically, when a voltage greater than the predetermined
volt (V) is applied between the backplate 13 and the diaphragm 14,
the portion of the annular region R2 of the diaphragm 14 begins to
move toward the second insulating protrusions 134; and when the
applied voltage gradually increases, the portion of the annular
region R2 of the diaphragm 14 will successively come into contact
with the second insulating protrusions 134 with different
protrusion heights. Therefore, the portion of the diaphragm 14 that
is displaceable relative to the backplate 13 (i.e. the portion that
is not affixed to the backplate 13) may be controllably chosen or
adjusted, so that the sensitivity of the diaphragm 14 of the MEMS
microphone M is tunable by adjusting the affixed range. The fixed
state of the portion of the annular region R2 of the diaphragm 14
can be cancelled when the voltage application is cancelled.
[0062] FIG. 4 schematically illustrates a cross-sectional view of a
MEMS microphone M, in accordance with some other embodiments. As
shown, the long apertures 141 (FIGS. 1 to 3) in the diaphragm 14 of
the MEMS microphone M are replaced by a number of vent holes 142.
FIG. 5 schematically illustrates the arrangement of the vent holes
142 in the diaphragm 14 in FIG. 4 from another viewing angle, in
accordance with some embodiments. As shown, four circular vent
holes 142 are formed in the diaphragm 14. However, it should be
appreciated that many variations and modifications can be made to
the embodiments of the disclosure.
[0063] FIG. 6 schematically illustrates a cross-sectional view of a
MEMS microphone M, in accordance with some other embodiments. As
shown, the MEMS microphone M in FIG. 6 differs from the MEMS
microphone M in FIG. 4 in that the diaphragm 14 further includes a
number of vent valves 143.
[0064] The vent valves 143 each have an open area that is variable
in response to a change in the acoustic pressure of the sound waves
passing therethrough. More specifically, the vent valve 143
includes at least one deflection portion 1431 (FIGS. 7A to 7C), and
the deflection portion 1431 is deflectable (as the arrows indicated
in FIG. 6) relative to the main body of the diaphragm 14, in
response to a change in the acoustic pressure of the sound waves
impinging on the diaphragm 14. FIGS. 7A to 7C schematically
illustrates various shapes of the vent valve 143 in the diaphragm
14 in FIG. 5 from another viewing angle, in accordance with some
embodiments. As shown, the deflection portion(s) 1431 of the vent
valve 143 may be in rectangular (FIG. 7A), fan-shaped (FIG. 7B) or
polygonal (FIG. 7C). However, it should be appreciated that many
variations and modifications can be made to the embodiments of the
disclosure.
[0065] FIG. 8 schematically illustrates a cross-sectional view of a
MEMS microphone M, in accordance with some other embodiments. As
shown, the MEMS microphone M in FIG. 8 differs from the MEMS
microphone M in FIGS. 1, 2A and 2B in that the first insulating
protrusion 133 is a hollow column having a hollow portion H
therein, and the protection layer 16 is omitted. This hollow first
insulating protrusion 133 connects the backplate 13 and (e.g. the
center of) the diaphragm 14 to reduce unexpected deformation of the
diaphragm 14 like as solid insulating protrusion 133 in FIG. 1.
[0066] FIG. 9 schematically illustrates a cross-sectional view of a
MEMS microphone M, in accordance with some other embodiments. As
shown, the MEMS microphone M in FIG. 9 differs from the MEMS
microphone M in FIG. 8 in that the diaphragm 14 further includes a
vent hole 142 or a vent valve 143 aligned with the hollow portion H
in the first insulating protrusion 133.
[0067] The embodiments of the present disclosure have some
advantageous features. By disposing at least one first insulating
protrusion between the backplate and the diaphragm to connect and
support the center region of the diaphragm, unexpected deformation
of the diaphragm during the displacement of the diaphragm is
reduced, thereby increasing the AOP of the diaphragm. However, in
some embodiments as shown in FIG. 10, the first insulating
protrusion (e.g., the first insulating protrusion 133 depicted in
FIGS. 1-4, 6, and 8-9) can also be omitted, and the additional
insulating layer 17 described above is provided and connected
between the first side S1 of the backplate 13 and the diaphragm 14
to support the center region of the diaphragm and increase the AOP
of the diaphragm.
[0068] Moreover, some long apertures may be provided in the
diaphragm and arranged in concentric circles to serve as a spring
in the diaphragm (in some alternative embodiments, the long
apertures may also be replaced by several vent holes and/or vent
valves) to reduce the diaphragm stiffness thereof, thereby
increasing the sensitivity of the diaphragm. Consequently, the
provided MEMS microphone can achieve high AOP and high sensitivity
simultaneously.
[0069] Although embodiments of the present disclosure and their
advantages have been described in detail, it should be understood
that various changes, substitutions and alterations can be made
herein without departing from the spirit and scope of the
disclosure as defined by the appended claims. For example, it will
be readily understood by those skilled in the art that many of the
features, functions, processes, and materials described herein may
be varied while remaining within the scope of the present
disclosure. Moreover, the scope of the present application is not
intended to be limited to the particular embodiments of the
process, machine, manufacture, composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present disclosure, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed, that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present disclosure. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps. In addition, each claim constitutes a separate
embodiment, and the combination of various claims and embodiments
are within the scope of the disclosure.
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