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DESCRIPTION JP2009017578

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DESCRIPTION JP2009017578
PROBLEM TO BE SOLVED: To provide a condenser microphone with high sensitivity. SOLUTION:
A plate 30 having a fixed electrode, and a diaphragm 10 which has a central portion 12a closer
to the plate than a near end 12b, a movable electrode 20 at the central portion 12a, and which
vibrates by sound waves And a spacer 40 holding the near end of the plate 30 and the near end
12 b of the diaphragm 10 while insulating it from 10. [Selected figure] Figure 1
コンデンサマイクロホン
[0001]
The present invention relates to a condenser microphone, and more particularly to a condenser
microphone using a semiconductor film.
[0002]
Conventionally, a condenser microphone that can be manufactured by applying a manufacturing
process of a semiconductor device is known.
The condenser microphone has an electrode on each of the plate and the diaphragm that vibrates
by sound waves, and the plate and the diaphragm are supported apart from each other by the
insulating spacer. The condenser microphone converts the change in capacitance due to the
displacement of the diaphragm into an electrical signal and outputs it. The sensitivity of the
condenser microphone is improved by increasing the ratio of displacement of the diaphragm to
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1
the distance between the electrodes, reducing the leak current of the spacer and reducing the
parasitic capacitance. Patent Document 1 discloses a condenser microphone in which each of a
plate for transmitting a sound wave and a diaphragm vibrated by the sound wave is formed of a
conductive thin film. However, even if the sound wave propagates to the diaphragm, the near end
(near the near end) is a portion close to the outer periphery fixed to the spacer. Since the
diaphragm and the plate made of the conductive thin film are hardly displaced, the respective
near ends near the outer periphery fixed to the spacer reduce the sensitivity of the condenser
microphone. Unexamined-Japanese-Patent No. 2002-223499
[0003]
An object of the present invention is to provide a condenser microphone with high sensitivity.
[0004]
(1) A condenser microphone for solving the above problems is a plate having a fixed electrode,
and a diaphragm having a central portion located closer to the plate than a near end portion, a
movable electrode at the central portion, and vibration due to sound waves And a spacer holding
the near end of the plate and the near end of the diaphragm while insulating the plate and the
diaphragm.
The central portion of the diaphragm is located closer to the plate than the near end of the
diaphragm. The central portion of the diaphragm vibrates with a larger displacement due to the
sound wave than the near end held by the spacer of the diaphragm. As a result, the movable
electrode formed in the central portion of the diaphragm vibrates with a larger displacement
than the near end portion at a position closer to the fixed electrode than the near end portion of
the diaphragm. Thus, a capacitor (hereinafter referred to as a microphone capacitor) formed of
the diaphragm and the plate by vibrating the movable electrode at a position closer to the fixed
electrode than the near end of the diaphragm and with a displacement larger than the near end. )
Can be increased. Here, the variable capacitance of the microphone capacitor is a capacitance
component that changes due to a sound wave in the capacitance of the microphone capacitor. By
increasing the variable capacitance of the microphone capacitor in this manner, the sensitivity of
the condenser microphone can be enhanced.
[0005]
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(2) The diaphragm is connected to a base including the near end, a relay connected to the plate
side of the central part of the base, and a side opposite to the base of the relay, the relay And the
movable electrode whose electrode area is larger than the connection area of the base. The
movable electrode is connected to the central portion of the base via the relay portion. As a
result, the movable electrode vibrates with a large amplitude with respect to the plate together
with the central portion of the base. The electrode area of the movable electrode is larger than
the connection area of the relay portion and the base. That is, since the movable electrode wider
than the central portion of the base vibrates with a large amplitude corresponding to the large
displacement of the central portion of the base, the variable capacitance of the capacitor formed
by the movable electrode and the plate is large. Since the variable capacitance of the microphone
capacitor can be increased by forming the capacitor of large variable capacitance with the
movable electrode and the plate as described above, the sensitivity of the condenser microphone
can be enhanced.
[0006]
(3) The portion of the diaphragm excluding at least the movable electrode may be formed of an
insulating material. By forming at least a portion of the diaphragm excluding the movable
electrode with an insulating material, it is possible to eliminate the parasitic capacitance formed
by the portion of the diaphragm excluding the movable electrode and the plate.
[0007]
(4) The diaphragm may be formed of a conductive material.
[0008]
(5) The conductive material may be polysilicon.
[0009]
(6) In the method of manufacturing a condenser microphone for solving the above problems,
after forming the movable electrode, a sacrificial layer is formed on the movable electrode, and
an opening for exposing a part of the movable electrode by etching is sacrificed. A conductor
layer is formed on the sacrificial layer, the conductive layer filling the opening, and the sacrificial
layer is removed after the conductive layer is formed.
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An opening that exposes a part of the movable electrode is formed in the sacrificial layer formed
on the movable electrode by etching, and a conductive layer in which the opening is buried is
formed on the sacrificial layer.
As a result, part of the movable electrode is connected to the part formed in the opening of the
sacrificial layer of the conductor layer, and the part formed on the sacrificial layer of the
conductor layer faces the movable electrode through the sacrificial layer . By removing the
sacrificial layer, the movable electrode is connected to the portion formed outside the opening of
the sacrificial layer of the conductive layer through the portion formed in the opening of the
sacrificial layer of the conductive layer. Condenser microphones can be manufactured. That is, a
portion of the conductor layer formed in the opening of the sacrificial layer corresponds to the
base, and a portion of the conductor layer formed outside the opening of the sacrificial layer
corresponds to the relay portion. be able to.
[0010]
In the present specification, "formed on ..." means "formed directly on ..." and "... on the upper side
unless there is a technical hindrance. It is meant to include both "forming through objects".
[0011]
Hereinafter, embodiments of the present invention will be described based on a plurality of
examples in the order of a condenser microphone and a method of manufacturing the same.
The components with the same reference numerals in the embodiments correspond to the
components of the other embodiments with the reference numbers.
[0012]
First Embodiment of Condenser Microphone Configuration of Condenser Microphone FIGS. 2 and
3 are schematic views for explaining the configuration of the condenser microphone according to
the first embodiment of the present invention. (A) of FIG. 2 is a top view, (B) is a bottom view.
FIG. 3 is a cross-sectional view taken along the line III-III in FIG.
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[0013]
As shown in FIG. 3, the condenser microphone 1 is composed of a diaphragm 10, a back plate
30, a spacer 40, a base 50 and the like. The condenser microphone 1 is a so-called silicon
microphone manufactured using a semiconductor manufacturing process. The diaphragm 10 is
composed of a base 12, a relay portion 16, a movable electrode 20 and the like. The diaphragm
10 is a conductive material such as polycrystalline silicon (hereinafter referred to as polysilicon).
Etc.) are formed. The plate-like base 12 vibrates by the sound wave propagating to the condenser
microphone 1. One end of the relay portion 16 is connected to the central portion 12 a of the
base 12. On the other hand, the other end of the relay portion 16 is connected to the movable
electrode 20. That is, the relay portion 16 electrically connects the base 12 and the movable
electrode 20 while supporting the movable electrode 20 on the back plate 30 side at the central
portion 12 a of the base 12. As a result, the movable electrode 20 vibrates at the amplitude of
the central portion 12 a of the base 12 on the back plate 30 side of the base 12. Further, when
the relay portion 16 forms an air gap between the base 12 and the movable electrode 20, it is
possible to prevent the base 12 vibrating by the sound wave from coming into contact with the
movable electrode 20. A plurality of through holes 22 are formed in the movable electrode 20
(see FIG. 2A). As a result, it is possible to reduce the air resistance applied to the movable
electrode 20 when the movable electrode 20 vibrates.
[0014]
The portion of the diaphragm 10 excluding at least the movable electrode 20 may be formed of
an insulating material. In that case, for example, a conducting wire for electrically connecting the
movable electrode 20 and the electrode 60 may be formed. By forming at least a portion of the
diaphragm 10 excluding the movable electrode 20 with an insulating material, the parasitic
capacitance formed by the portion of the diaphragm 10 excluding the at least the movable
electrode 20 and the back plate 30 can be removed. In addition, the movable electrode 20 may
be formed of a plurality of layers of a conductive layer and an insulating layer. Further, the shape
of the base 12 of the diaphragm 10 and the movable electrode 20 may be a disk shape as shown
in FIG. 2A, or may be a shape other than the disk shape. Further, the shape of the through hole
22 of the movable electrode 20 is not particularly limited, and the through hole 22 may be
circular as shown in FIG. 1B or may be another shape.
[0015]
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The spacer 40 is formed of an insulating material, for example, SiO2. The spacer 40 separates the
diaphragm 10 and the back plate 30 from each other to form an air gap between the diaphragm
10 and the back plate 30 while insulating the diaphragm 10 and the back plate 30. The spacer
40 may be formed of a plurality of conductive layers and insulating layers in which at least a
layer connected to the diaphragm 10 and the back plate 30 is formed of an insulating material.
[0016]
The back plate 30 as a plate is made of a conductive material, for example, a semiconductor such
as polysilicon. A plurality of through holes 32 are formed in the back plate 30 (see FIG. 2 (B)).
The shape of the through hole 32 is not particularly limited, and the through hole 32 may be
circular as shown in FIG. 1C or may be another shape. The conductive back plate 30 corresponds
to the "fixed electrode" described in the claims in its entirety. The back plate 30 may be
configured of a base formed of an insulating material, a fixed electrode formed of a conductive
material on the base, or the like.
[0017]
The base 50 is formed on the side opposite to the diaphragm 10 of the back plate 30 and has an
opening 52 that exposes at least the formation area of the through hole 32 of the back plate 30.
By forming such an opening 52 in the base 50, it is possible to form a new air gap
communicating with the air gap between the diaphragm 10 and the back plate 30 described
above. By increasing the volume of the air gap, it is possible to suppress the increase in internal
pressure of the condenser microphone 1 when the diaphragm 10 vibrates.
[0018]
The condenser microphone 1 is connected in series to the resistor 300, and the series circuit
including the condenser microphone 1 and the resistor 300 is connected to the bias power
supply circuit 302. Specifically, to the electrode 60 of the diaphragm 10, for example, a lead 304
connected to one end of the resistor 300 is connected. A conducting wire 306 is connected to the
electrode 62 of the back plate 30, for example, connected to the ground of the substrate on
which the condenser microphone 1 is mounted. The other end of the resistor 300 is connected to
the output end of the bias power supply circuit 302. As the resistor 300, one having a relatively
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large electric resistance is used. Specifically, the resistor 300 desirably has an electrical
resistance of GΩ order. The preamplifier 308 is connected to the contact of the capacitor
microphone 1 and the resistor 300 via the capacitor 310.
[0019]
2. Operation of Condenser Microphone FIG. 1 is a schematic view for explaining the operation
of the condenser microphone 1. A state in which the diaphragm 10 is not vibrated by the sound
wave (hereinafter referred to as a static state). ), A capacitor (hereinafter referred to as a
microphone capacitor) formed by the diaphragm 10 and the back plate 30. ), Charge
corresponding to the capacitance is accumulated.
[0020]
When the sound wave propagates to the diaphragm 10, the diaphragm 10 vibrates by the sound
wave. When the diaphragm 10 vibrates, the distance between the diaphragm 10 and the back
plate 30 changes due to the vibration, so the capacitance of the microphone capacitor changes.
Hereinafter, a state in which the diaphragm 10 is vibrated by the sound wave is referred to as a
dynamic state. Further, among capacitances of the microphone capacitor, a capacitance
component that changes due to sound waves is referred to as a variable capacitance. On the
other hand, since the diaphragm 10 is connected to the resistor 300 having a large electric
resistance via the electrode 60, even if the capacitance of the microphone capacitor changes as
described above, the charge accumulated in the static state is the resistor There is almost no flow
through 300. That is, the charge stored in the microphone capacitor can be regarded as not
changing even in the dynamic state. As a result, the change in capacitance of the microphone
capacitor due to the sound wave can be taken out as a change in voltage between the diaphragm
10 and the back plate 30. Specifically, by amplifying the change in voltage of the diaphragm 10
with respect to the ground in the preamplifier 308, the change in capacitance due to the sound
wave of the microphone capacitor is extracted as an electric signal. Therefore, the sensitivity of
the condenser microphone 1 can be enhanced by increasing the variable capacitance of the
microphone capacitor.
[0021]
The base 12 of the diaphragm 10 vibrates with the near end 12 b held by the spacer 40 as a
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fixed end. Therefore, the central portion 12a which is the farthest from the proximal end 12b of
the base 12 is displaced the most by the vibration of the base 12 (see the arrows 400 and 402
shown in FIG. 1). Since the movable electrode 20 of the diaphragm 10 is fixed to the central
portion 12a of the base 12 via the relay portion 16 as described above, the movable electrode 20
vibrates at the maximum displacement of the base 12 (see arrow 404 shown in FIG. 1) ). Further,
the electrode area of the movable electrode 20 of the diaphragm 10 is larger than the connection
area of the relay portion 16 and the base 12 (refer to the area of the region hatched in FIG. 2A).
That is, in the condenser microphone 1, the movable electrode 20 wider than the central portion
12 a of the base 12 vibrates with the displacement of the central portion 12 a of the base 12,
that is, the maximum displacement of the base 12. Furthermore, in the condenser microphone 1,
the entire movable electrode 20 vibrates at a position closer to the back plate 30 than the base
12 of the diaphragm 10. As a result, the capacitance of the capacitor formed by the movable
electrode 20 of the diaphragm 10 and the back plate 30 largely changes due to the acoustic
wave. Since the variable capacitance of the microphone capacitor can be increased by forming
the capacitor having a large variable capacitance with the movable electrode 20 and the back
plate 30 as described above, the sensitivity of the condenser microphone 1 can be enhanced.
[0022]
First Embodiment of Method of Manufacturing Condenser Microphone FIGS. 4 to 7 are schematic
views for explaining a first embodiment of a method of manufacturing the capacitor microphone
1. First, as shown in FIG. 4 (A1), a plurality of recesses 102 are formed in the substrate 100. The
substrate 100 is a semiconductor substrate such as a single crystal silicon substrate, for example.
The recess 102 is, for example, a cylindrical shape having a diameter of 2.0 μm to 4.0 μm and a
depth of 2.0 μm to 4.0 μm. Specifically, the recess 102 is formed, for example, as follows. First,
as shown in FIG. 4A, a resist layer 104 is formed over the substrate 100 to expose a portion of
the substrate 100 where the concave portion 102 is to be formed. More specifically, a resist is
applied onto the substrate 100 to form a resist film. Then, a mask of a predetermined shape is
disposed, and the resist film is exposed and developed to remove unnecessary resist film. For
removing the resist film, a resist stripping solution such as NMP (N-methyl-2-pyrrolidone) is
used. Next, the substrate 100 exposed from the resist layer 104 is etched by RIE (Reactive Ion
Etching) to form a recess 102 in the substrate 100.
[0023]
Next, the first insulating layer 106 is formed in the concave portion 102 (see FIG. 4A3).
Specifically, the first insulating layer 106 is formed, for example, as follows. First, as shown in
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FIG. 4 (A2), the resist layer 104 is removed, and an SiO 2 layer 105 in which the recess 102 is
buried is formed on the substrate 100 by plasma CVD (Chemical Vapor Deposition) or the like.
Then, as shown in FIG. 4 (A3), the SiO 2 layer 105 and the substrate 100 are polished and
planarized by CMP (Chemical Mechanical Polishing) or the like to leave the first insulating layer
106 of SiO 2 only in the concave portion 102. .
[0024]
Next, as illustrated in FIG. 4A4, the second insulating layer 108 having a thickness of 2.0 μm to
4.0 μm, for example, is formed on the surfaces of the substrate 100 and the first insulating layer
106 by plasma CVD or the like. It is desirable that the second insulating layer 108 and the third
insulating layer 116 and the fourth insulating layer 118 described later be formed of the same
material as the first insulating layer 106. By forming the second insulating layer 108 to the
fourth insulating layer 118 with the same material as the first insulating layer 106, the second
insulating layer 108 to the fourth insulating layer 118 can be formed in the step of removing the
insulating layer described later. It can be removed together with the insulating layer 106.
[0025]
Next, a first conductive layer 110 having a through hole 110a is formed on the second insulating
layer 108 (see FIG. 5 (A5)). The first conductive layer 110 is formed to a thickness of, for
example, 0.5 μm to 1.5 μm. Specifically, the first conductive layer 110 is formed, for example,
as follows. First, as shown in FIG. 4A 4, the P <+> polysilicon layer 112 is formed on the second
insulating layer 108. Here, P <+> polysilicon refers to polysilicon including an impurity serving as
an acceptor. More specifically, a polysilicon layer is formed on the second insulating layer 108
by plasma CVD or the like, and B (boron) or the like as an impurity is ion-implanted into the
polysilicon layer. Then, P <+> polysilicon layer 112 is formed by annealing the polysilicon layer
after ion implantation. Next, a resist layer 114 is formed on the P <+> polysilicon layer 112 to
expose an unnecessary part such as a part for forming the through hole 110 a of the P <+>
polysilicon layer 112. Next, as shown in FIG. 5 (A5), the P <+> polysilicon layer 112 exposed from
the resist layer 114 is etched by RIE or the like to form P <+> polysilicon on the second insulating
layer 108. The first conductive layer 110 is formed. The first conductive layer 110 corresponds
to the movable electrode 20. The through hole 110 a corresponds to the through hole 22 of the
movable electrode 20.
[0026]
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Next, the first conductive layer 110 and the flat third insulating layer 116 are formed over the
second insulating layer 108 (see FIG. 5 (A7)). Specifically, the third insulating layer 116 is
formed, for example, as follows. First, as shown in FIG. 5 (A6), the resist layer 114 is removed,
and a SiO 2 layer 115 thicker than the first conductive layer 110 is formed on the second
insulating layer 108 by plasma CVD or the like. Thereby, the first conductive layer 110 is buried
in the SiO 2 layer 115. Then, as shown in FIG. 5 (A7), the SiO 2 layer 115 and the first conductive
layer 110 are polished and planarized by CMP or the like. Next, a fourth insulating layer 118 of
0.3 μm to 2.0 μm, for example, is formed by plasma CVD or the like on the surfaces of the
substrate 100 and the third insulating layer 116 (see FIG. 5A8).
[0027]
Next, a second conductive layer 120 connected to the first conductive layer 110 is formed over
the fourth insulating layer 118 (see FIG. 6A10). The second conductive layer 120 is formed to a
thickness of, for example, 0.5 μm to 1.5 μm. Specifically, the second conductive layer 120 is
formed, for example, as follows. First, the through hole 122 for exposing the first conductive
layer 110 is formed in the fourth insulating layer 118 (see FIG. 5 (A9)). More specifically, as
shown in FIG. 5 (A 8), a resist layer 124 for exposing a portion of the fourth insulating layer 118
where the through holes 122 are to be formed is formed on the fourth insulating layer 118 in
the same step as the resist layer 114. Form. Then, as shown in FIG. 6 (A9), the fourth insulating
layer 118 is etched by etching the portion of the fourth insulating layer 118 exposed from the
resist layer 124 with hydrofluoric acid or the like until the first conductive layer 110 is exposed.
The through holes 122 are formed. Next, as shown in FIG. 6 (A10), the second conductive layer
120 of P <+> polysilicon, for example, is formed on the surfaces of the first conductive layer 110
and the fourth insulating layer 118 exposed from the through holes 122. It is formed in the same
step as the one conductive layer 110. The portion formed in the through hole 122 of the fourth
insulating layer 118 of the second conductive layer 120 corresponds to the relay portion 16 of
the diaphragm 10. A portion of the second conductive layer 120 formed outside the through
holes 122 of the fourth insulating layer 118 and formed on a portion removed in the step of
removing the insulating layer described later of the fourth insulating layer 118 A portion
corresponds to the base 12 of the diaphragm 10.
[0028]
Next, the electrode 126 and the electrode 128 are formed over the substrate 100 and the second
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conductive layer 120, respectively (see FIG. 7 (A13)). The electrodes 126 and 128 are formed to
have a thickness of, for example, 0.3 μm to 1.0 μm. Specifically, the electrode 126 and the
electrode 128 are formed, for example, as follows. First, as illustrated in FIG. 6A11, part of the
substrate 100 is exposed. More specifically, a resist layer 130 for masking the remaining portion
of the second conductive layer 120 is formed on the second conductive layer 120 in the same
process as the resist layer 114. Then, the second conductive layer 120, the fourth insulating
layer 118, the third insulating layer 114, and the second insulating layer 108 exposed from the
resist layer 130 are etched by RIE to expose the substrate 100. Next, as shown in FIG. 6 (A12),
the resist layer 130 is removed to form a through hole 132a for exposing the portion of the
substrate 100 where the electrode 126 is to be formed, and a portion where the electrode 128 of
the second conductive layer 120 is to be formed. A resist layer 132 having through holes 132 b
exposing the resist is formed in the same process as the resist layer 114. Next, as shown in FIG. 7
(A13), an Al electrode 126 and an Al electrode 128 are formed in the through holes 132a and
the through holes 132b, for example, by sputtering Al using a resist layer 132 as a mask. Then,
the resist layer 132 is removed.
[0029]
Next, by removing a part of the substrate 100 from the back surface side of the substrate 100
until the bottom of the recess 102 formed in the substrate 100 is removed, the recess 134 that
exposes the first insulating layer 106 on the bottom surface is removed. It forms (refer FIG. 7
(A15)). The back surface of the substrate 100 refers to the surface opposite to the surface on
which the recess 102 of the substrate 100 is formed. The recess 134 is formed in, for example, a
cylindrical shape having a diameter of 700 μm. Specifically, the recess 134 is formed, for
example, as follows. First, as shown in FIG. 7 (A14), a resist layer 136 which exposes only a
portion where the concave portion 134 is to be formed is formed on both sides of the substrate
100 in the same process as the resist layer 114. Next, as shown in FIG. 7 (A15), the recessed
portion 134 is formed in the substrate 100 by removing the portion of the substrate 100
exposed from the resist layer 136 by Deep RIE or the like. The portion from the bottom of the
recess 134 to the surface of the substrate 100 corresponds to the back plate 30.
[0030]
Next, as shown in FIG. 7 (A16), the first insulating layer 106 to the fourth insulating layer 118
(hereinafter, referred to as insulating layers). ) Except for a portion formed between the near end
of the second conductive layer 120 and the substrate 100. Specifically, the insulating layer is
removed by wet etching, for example. For example, the insulating layer of SiO 2 is removed by an
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etching solution such as hydrofluoric acid. The etching solution dissolves the insulating layer in
order of the first insulating layer 106, the second insulating layer 108, the third insulating layer
114, and the fourth insulating layer 118 exposed at the bottom of the recess 134. The removed
portion of the insulating layer corresponds to the sacrificial layer described in the claims.
Further, the remaining portion of the insulating layer corresponds to the spacer 40.
[0031]
In order to leave the insulating layer formed between the near end of the second conductive
layer 120 and the substrate 100, for example, the second insulating layer 108 to the fourth
insulating layer 118 each have a thickness of 4.0 μm and a thickness of When forming with 2.0
μm and 1.5 μm thickness, the distance from the outer wall of the second insulating layer 108
to the recess 102 formed on the outermost side of the substrate 100 is 17.5 μm , The second
insulating layer 108 to the fourth insulating layer 118. In this case, the spacer 40 having a
circumferential width of 10.0 μm (= 17.5 μm− (4.0 μm + 2.0 μm + 1.5 μm)) can be formed.
[0032]
Second Embodiment of Method of Manufacturing Condenser Microphone FIGS. 8 to 11 are
schematic views for explaining a second embodiment of a method of manufacturing the capacitor
microphone 1. First, as shown in FIG. 8 (A1), the first insulating layer 200 is formed over the
substrate 100. Specifically, for example, the first insulating layer 200 is formed by growing SiO 2
on the substrate 100 by plasma CVD or the like. Note that this process can be omitted by using
an SOI substrate.
[0033]
Next, a first conductive layer 202 having through holes 202 a is formed on the first insulating
layer 200. Specifically, the first conductive layer 202 is formed, for example, as follows. First, a P
<+> polysilicon layer is formed on the first insulating layer 200 in the same process as the first
conductive layer 110 according to the first embodiment of the manufacturing method. Next, a
resist layer is formed on the P <+> polysilicon layer to expose a portion of the P <+> polysilicon
layer for forming the through hole 202a. Next, the P <+> polysilicon layer exposed from the resist
layer is etched by RIE or the like to form the first conductive layer 202 of P <+> polysilicon on
the first insulating layer 200. The first conductive layer 202 corresponds to the back plate 30.
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[0034]
Next, as shown in FIG. 8A 2, the first conductive layer 202 and the flat second insulating layer
204 are formed over the first insulating layer 200. Specifically, for example, the second
insulating layer 204 is formed in the same process as the third insulating layer 116 according to
the first embodiment of the manufacturing method. It is desirable that the second insulating layer
204 and the third insulating layer 206 to the fifth insulating layer 211 described later be formed
of the same material as the first insulating layer 200. By forming the second insulating layer 204
to the fifth insulating layer 211 with the same material as the first insulating layer 200, the
second insulating layer 204 to the fifth insulating layer 211 can be formed in the process of
removing the insulating layer described later. It can be removed together with the insulating
layer 200. Next, the third insulating layer 206 is formed on the surfaces of the first conductive
layer 202 and the second insulating layer 204.
[0035]
Next, as shown in FIG. 8A3, a second conductive layer 208 having through holes 208a is formed
on the third insulating layer 206. Specifically, for example, the second conductive layer 208 is
formed in the same process as the first conductive layer 110 according to the first embodiment
of the manufacturing method. The second conductive layer 208 corresponds to the movable
electrode 20. Next, as shown in FIG. 8A 4, the second conductive layer 208 and the flat fourth
insulating layer 210 are formed over the third insulating layer 206. Specifically, for example, the
fourth insulating layer 210 is formed in the same process as the third insulating layer 116
according to the first embodiment of the manufacturing method.
[0036]
Next, as illustrated in FIG. 8A5, the fifth insulating layer 211 is formed over the surfaces of the
second conductive layer 208 and the fourth insulating layer 210. Specifically, for example, SiO 2
is grown by plasma CVD or the like on the surfaces of the second conductive layer 208 and the
fourth insulating layer 210 to form the fifth insulating layer 211 of SiO 2. Next, as shown in FIG.
8A 6, a third conductive layer 212 connected to the second conductive layer 208 is formed over
the fifth insulating layer 211. Specifically, for example, the third conductive layer 212 of P <+>
polysilicon is formed by the same process as the second conductive layer 120 according to the
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first embodiment of the manufacturing method. Next, as shown in FIG. 8 (A7), the first
conductive layer 202 is exposed. Specifically, for example, a resist layer 214 is formed on the
third conductive layer 212 to mask the remaining portion of the third conductive layer 212.
Then, the third conductive layer 212, the fifth insulating layer 211, the fourth insulating layer
210, and the third insulating layer 206 exposed from the resist layer 214 are etched by RIE or
the like to expose the first conductive layer 202.
[0037]
Next, as shown in FIG. 8 (A8), a structure (hereinafter, referred to as a laminated body) stacked
on the substrate 100. A sixth insulating layer 216 covering the surface of Specifically, for
example, the sixth insulating layer 216 is formed on the surface of the structure formed on the
surface side of the substrate 100 by growing SiN by low pressure CVD or the like. At this time,
the first conductive layer 202 and the third conductive layer 212 are respectively fixed to the
sixth insulating layer 216 on the side where the first conductive layer 202 of the laminate is
exposed. As a result, even if the fifth insulating layer 211 is removed from the first insulating
layer 200 near the sixth insulating layer 216 in the process described later, the first conductive
layer 202 and the third conductive layer 212 are held by the sixth insulating layer 216 Be done.
The first conductive layer 202 and the third conductive layer 212 may be fixed to the sixth
insulating layer 216 at a plurality of places. In addition, the first conductive layer 202 and the
third conductive layer 212 are fixed to the sixth insulating layer 216 all around by leaving the
laminate in a cylindrical shape including the formation region of the second conductive layer 208
inside. It is also good.
[0038]
Next, the electrode 218 and the electrode 220 are formed over the first conductive layer 202
and the third conductive layer 212, respectively (see FIG. 10A10). Specifically, the electrodes 218
and 220 are formed, for example, as follows. First, as shown in FIG. 10 (A9), a resist layer 222 for
exposing a part of the sixth insulating layer 216 on the first conductive layer 202 and a part of
the sixth insulating layer 216 on the third conductive layer 212 Form Next, portions of the sixth
insulating layer 216 exposed from the resist layer 222 are etched by RIE or the like until they
reach the first conductive layer 202 and the third conductive layer 212, thereby respectively
forming the through holes 216a and the through holes 216b. The sixth insulating layer 216 is
formed. Next, as shown in FIG. 10 (A10), an Al electrode 218 and an electrode 220 are formed in
the through holes 216a and the through holes 216b, respectively, by sputtering Al using the
resist layer 222 as a mask. Then, the resist layer 222 is removed.
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[0039]
Next, an opening 224 which exposes the first insulating layer 200 is formed in the substrate 100
(see FIG. 11A12). Specifically, the opening 224 is formed, for example, as follows. First, as shown
in FIG. 11A11, a resist layer 226 which exposes only part of the back surface of the substrate
100 is formed on both sides of the substrate 100. Next, as shown in FIG. 11A11, the opening
portion 224 is formed in the substrate 100 by removing the portion exposed from the resist
layer 226 of the substrate 100 by Deep RIE or the like until the first insulating layer 200 is
reached.
[0040]
Next, the first insulating layer 200 to the fifth insulating layer 211 (hereinafter, referred to as
insulating layers). ) Except for a part formed between the first conductive layer 202 and the third
conductive layer 212 (see FIG. 11 (A13)). The insulating layer is removed by wet etching. For
example, hydrofluoric acid is used as the etching solution. The etching solution dissolves the
insulating layer in the order of the first insulating layer 200, the second insulating layer 204, the
third insulating layer 206, the fourth insulating layer 210, and the fifth insulating layer 211
exposed to the opening 224.
[0041]
At this time, in the portion where the sixth insulating layer 216 of the stack is formed, the
insulating layer can be removed by wet etching using the sixth insulating layer 216 as a stopper
layer. As described above, even if the insulating layer is removed to reach the sixth insulating
layer 216, the first conductive layer 202 and the third conductive layer 212 are held by the sixth
insulating layer 216. In this case, the sixth insulating layer 216 corresponds to the spacer 40.
[0042]
The schematic diagram for demonstrating the capacitor | condenser microphone by this
invention. FIG. 1 is a plan view of a condenser microphone according to the present invention.
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15
Sectional drawing by the III-III line of FIG. 2 (A). FIG. 7 is a schematic view for explaining the
manufacturing method according to the first embodiment of the manufacturing method. FIG. 7 is
a schematic view for explaining the manufacturing method according to the first embodiment of
the manufacturing method. FIG. 7 is a schematic view for explaining the manufacturing method
according to the first embodiment of the manufacturing method. FIG. 7 is a schematic view for
explaining the manufacturing method according to the first embodiment of the manufacturing
method. The schematic diagram for demonstrating the manufacturing method by 2nd Example of
a manufacturing method. FIG. 7 is a schematic view for explaining the manufacturing method
according to the first embodiment of the manufacturing method. FIG. 7 is a schematic view for
explaining the manufacturing method according to the first embodiment of the manufacturing
method. FIG. 7 is a schematic view for explaining the manufacturing method according to the
first embodiment of the manufacturing method.
Explanation of sign
[0043]
Reference Signs List 1 condenser microphone, 10 diaphragm, 12a central portion (central
portion of diaphragm, central portion of base), 12 base, 12b near end (near end of base), 16
relays, 20 movable electrodes, 30 back plate (plate ), 40 spacers
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16
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