close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2010103701

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2010103701
To reduce the time required for manufacturing a MEMS sensor. In a silicon microphone (1), a
through hole (3) is formed in a substrate (2), and a diaphragm (7) is disposed opposite to the
through hole (3). The diaphragm 7 is formed to have a size smaller than that of the through hole
3 when viewed in the opposite direction to the through hole 3. The diaphragm 7 is supported by
a plurality of support portions 8 extending from the peripheral edge thereof to the outside of the
peripheral edge of the through hole 3. [Selected figure] Figure 1
MEMSセンサ
[0001]
The present invention relates to various sensors (MEMS sensors) manufactured by MEMS (Micro
Electro Mechanical Systems) technology.
[0002]
Recently, since MEMS sensors have begun to be mounted on mobile phones and the like, the
attention of MEMS sensors is rapidly increasing.
For example, a silicon microphone (Si microphone) is a typical MEMS sensor. FIG. 5 is a
schematic cross-sectional view showing the structure of a conventional silicon microphone. The
silicon microphone 101 includes a silicon substrate 102. A through hole 103 having a
trapezoidal cross section is formed in the central portion of the silicon substrate 102.
18-04-2019
1
[0003]
A circular thin film diaphragm 104 is provided on the silicon substrate 102. The diaphragm 104
faces the through hole 103, and a portion 105 around the through hole 103 on the surface of
the silicon substrate 102 (hereinafter referred to as "through hole peripheral portion 105" in the
section of background art and problems to be solved by the invention. ) And is arranged in a
floating state from the through hole peripheral portion 105 with a minute gap therebetween.
[0004]
A support portion 106 is integrally formed on the diaphragm 104. The support portion 106
extends laterally from the peripheral edge of the diaphragm 104 and is held between the first
insulating film 107 and the second insulating film 108, the tip of which is stacked on the surface
of the silicon substrate 102. The diaphragm 104 is vibratably supported by the support portion
106 in the direction opposite to the silicon substrate 102.
[0005]
On the lower surface of the diaphragm 104, a plurality of stoppers 109 project at positions
facing the through hole peripheral portion 105. The stopper 109 limits the vibration width of the
diaphragm 104 by coming into contact with the through hole peripheral portion 105 when an
excessive pressure is applied to the diaphragm 104. This can prevent damage to the diaphragm
104 or the support portion 106 due to excessive vibration of the diaphragm 104.
[0006]
A back plate 110 is provided above the diaphragm 104. The back plate 110 is opposed to the
diaphragm 104 with a minute gap. The outermost surface of the silicon microphone 101 is
covered with a protective film 111. Specifically, the protective film 111 continuously covers the
surfaces of the first insulating film 107, the second insulating film 108, and the silicon substrate
102, and a distance between the surface of the silicon substrate 102 and the diaphragm 7 with
the diaphragm 7 is set. It rises up so as to surround it and covers the upper surface of the back
18-04-2019
2
plate 110. Thus, a space 112 partitioned by the protective film 111 is formed on the silicon
substrate 102, and the diaphragm 104 is not in contact with the silicon substrate 102, the back
plate 110 and the protective film 111 in the space 112. It is arranged by.
[0007]
In the back plate 110 and the protective film 111, a plurality of through holes 113 are formed
continuously through them. Thus, the space 112 inside the protective film 111 communicates
with the outside on the back surface side of the silicon substrate 102 through the through hole
103 and communicates with the outside on the front surface side of the silicon substrate 102
through the through hole 113. There is. The diaphragm 104 and the back plate 110 form a
capacitor that uses them as counter electrodes. A predetermined voltage is applied to this
capacitor. In that state, when the diaphragm 104 vibrates due to sound pressure (sound wave),
the capacitance of the capacitor changes, and the voltage fluctuation between the diaphragm 104
and the back plate 110 due to the change of the capacitance is extracted as an audio signal.
[0008]
In the manufacturing process of the silicon microphone 101, the first sacrificial layer is formed
on the silicon substrate 102, and the diaphragm 104 is formed on the first sacrificial layer.
Thereafter, a second sacrificial layer is formed to cover the entire surface of the diaphragm 104,
and a back plate 110 is formed on the second sacrificial layer. After forming the back plate 110,
a protective film 111 is formed to cover the first sacrificial layer, the second sacrificial layer, and
the back plate 110. Then, after the through holes 103 are formed in the silicon substrate 102
and the through holes 113 are formed in the protective film 111, an etching solution is supplied
from the through holes 103 and 113 to the inside of the protective film 111, and the first
sacrificial layer and the first sacrificial layer 2 The sacrificial layer is removed. As a result, the
diaphragm 104 floats from the through hole peripheral portion 105, and a space of a minute
distance is formed between the diaphragm 104 and the back plate 110. JP 2001-518246 gazette
[0009]
Since the stopper 109 must be provided in the portion of the diaphragm 104 facing the through
hole peripheral portion 105, the opposing area between the diaphragm 104 and the through
18-04-2019
3
hole peripheral portion 105 is relatively large. On the other hand, since the distance between the
diaphragm 104 and the through hole peripheral portion 105 is relatively small, the etching
solution does not easily enter the narrow portion between the diaphragm 104 and the through
hole peripheral portion 105. Therefore, it takes a long time (for example, 20 to 30 minutes) to
remove the first sacrificial layer from between the diaphragm 104 and the through hole
peripheral portion 105, which causes the manufacturing of the silicon microphone 101 to take a
long time. It is one.
[0010]
Therefore, an object of the present invention is to provide a MEMS sensor capable of shortening
the time required for manufacturing.
[0011]
In order to achieve the above object, the invention according to claim 1 has a substrate in which
a through hole is formed, and a substrate having a size equal to or less than the size of the
through hole, disposed opposite to the through hole and viewed in the opposite direction. A
MEMS sensor comprising: a vibrating membrane; and a plurality of supports extending from the
periphery of the vibrating membrane to the outer side than the periphery of the through hole
and vibratably supporting the vibrating membrane.
In this MEMS sensor, a through hole is formed in the substrate, and a vibrating film is disposed
opposite to the through hole. The vibrating membrane is formed to have a size equal to or less
than the size of the through hole when viewed in the opposite direction to the through hole. The
vibrating membrane is supported by a plurality of supports extending from the peripheral edge
to the outer side than the peripheral edge of the through hole. As a result, the supporting
strength of the vibrating membrane is increased, so that the vibrating membrane does not vibrate
excessively even if an excessive pressure is applied to the vibrating membrane. Therefore,
damage to the vibrating membrane and the support portion due to excessive vibration of the
vibrating membrane can be prevented.
[0012]
In the manufacturing process of the MEMS sensor, a sacrificial layer is formed on the substrate, a
vibrating film and a support are formed on the sacrificial layer, a through hole is formed in the
18-04-2019
4
substrate, and an etchant is supplied to the sacrificial layer through the through hole. As a result,
the sacrificial layer is removed. Since the vibrating membrane and the peripheral portion of the
through hole in the substrate do not face each other (in the direction orthogonal to the surface of
the substrate) or only a part thereof, and not across the entire circumference, the etchant serves
as a sacrificial layer Can be well supplied. As a result, the sacrificial layer on the substrate can be
removed in a short time, which in turn can reduce the time required for manufacturing the
MEMS sensor.
[0013]
As described in claim 2, the vibrating membrane may have a size smaller than the size of the
through hole when viewed in the opposite direction to the through hole. Further, as described in
claim 3, the vibrating membrane may be disposed inside the peripheral edge of the through hole
as viewed in the direction opposite to the through hole. In this case, the vibrating film does not
face the peripheral portion of the through hole in the substrate (in the direction orthogonal to
the surface of the substrate). Therefore, although the vibration width of the vibrating membrane
is not limited by the contact between the vibrating membrane and the substrate, there is a
possibility that the vibrating membrane vibrates excessively because the vibrating membrane is
supported by a plurality of supporting portions. Absent.
[0014]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the attached drawings. FIG. 1 is a schematic cross-sectional view showing a structure of a silicon
microphone according to an embodiment of the present invention. The silicon microphone 1 is a
sensor (MEMS sensor) manufactured by MEMS technology. The silicon microphone 1 includes a
substrate 2 made of silicon. A through hole 3 having a circular shape in a plan view is formed in
a central portion of the substrate 2.
[0015]
The first insulating film 4 is stacked on the substrate 2. The first insulating film 4 is made of, for
example, SiO 2 (silicon oxide). The second insulating film 5 is stacked on the first insulating film
4. The second insulating film 5 is made of, for example, SiO 2. The first insulating film 4 and the
second insulating film 5 are removed from above the region including the through hole 3 in plan
18-04-2019
5
view, and the portion 6 around the through hole 3 in the surface (upper surface) of the substrate
2 (hereinafter referred to as “through hole It is called "peripheral part 6". ) Is exposed from the
first insulating film 4 and the second insulating film 5.
[0016]
Above the substrate 2, a diaphragm 7 is provided opposite to the through hole 3. The diaphragm
7 is formed in a circular shape having a diameter smaller than that of the through hole 3 in a
plan view. And the diaphragm 7 is arrange | positioned rather than the periphery of the throughhole 3 in planar view. A plurality of support portions 8 are integrally formed on the diaphragm 7.
Each support portion 8 extends from the peripheral edge of the diaphragm 7 to the outer side
than the peripheral edge of the through hole 3 and is sandwiched between the first insulating
film 4 and the second insulating film 5. The diaphragm 7 is vibratably supported in the direction
orthogonal to the surface of the substrate 2 by the plurality of support portions 8. The
diaphragm 7 and the support portion are made of, for example, doped polysilicon (polysilicon to
which conductivity is imparted by doping with impurities).
[0017]
A back plate 9 is provided above the diaphragm 7. The back plate 9 has a circular outer shape in
plan view having a diameter smaller than that of the diaphragm 7 and is opposed to the
diaphragm 7 with a gap. A plurality of holes 10 are formed in the back plate 9. バックプレート
9は、たとえば、ドープトポリシリコンからなる。 The outermost surface of the silicon
microphone 1 is covered with a protective film 11. Specifically, the protective film 11
continuously covers the surfaces of the first insulating film 4, the second insulating film 5 and
the substrate 2 and has a distance from the surface of the substrate 2 to the diaphragm 7 and the
periphery of the diaphragm 7. It rises to surround and covers the upper surface (the surface
opposite to the diaphragm 7 side) of the back plate 9. Thus, a space 12 partitioned by the
protective film 11 is formed on the substrate 2, and the diaphragm 7 is disposed in the space 12
so as not to be in contact with the substrate 2, the back plate 9 and the protective film 11. It is
done. The protective film 11 is made of, for example, SiN (silicon nitride).
[0018]
The protective film 11 has penetrated into the holes 10 of the back plate 9. The portion 13 in the
18-04-2019
6
hole 10 of the protective film 11 protrudes downward from the hole 10 below the lower surface
(the surface facing the diaphragm 7) of the back plate 9 and is an upper surface for preventing
contact between the diaphragm 7 and the back plate 9. It functions as a stopper. In the protective
film 11, holes 14 are formed in communication with the holes 10 at respective positions facing
the holes 10 in which the protective film 11 does not enter. Thus, the space 12 inside the
protective film 11 communicates with the outside on the back surface side of the substrate 2
through the through hole 3 and communicates with the outside on the front surface side of the
substrate 2 through the holes 10 and 14. .
[0019]
The diaphragm 7 and the back plate 9 form a capacitor that uses them as the counter electrode.
A predetermined voltage is applied to the capacitor (between the diaphragm 7 and the back plate
9). In that state, when the diaphragm 7 vibrates due to sound pressure (sound wave), the
capacitance of the capacitor changes, and the voltage fluctuation between the diaphragm 7 and
the back plate 9 due to the change in capacitance is extracted as an audio signal (output Will be
[0020]
FIG. 2 is a schematic plan view of the diaphragm and the support shown in FIG. The diaphragm 7
is opposed to the through hole 3 whose whole is shown by a phantom line. In this embodiment,
four supports 8 are provided. The four supports 8 are arranged at equal angular intervals (ie, 90
degrees apart) around the diaphragm 7. Thus, the diaphragm 7 is supported at four points from
four directions.
[0021]
3A to 3E are schematic cross-sectional views for explaining the method of manufacturing the
silicon microphone shown in FIG. First, as shown in FIG. 3A, the oxide film 21 made of SiO 2 is
formed on the entire surface of the silicon wafer W which is the base of the substrate 2 by
thermal oxidation. Hereinafter, the oxide film 21 formed on the surface of the silicon wafer W is
referred to as a surface oxide film 21A, and the oxide film 21 formed on the back surface of the
silicon wafer W is distinguished as a back surface oxide film 21B. A circular groove 22 is formed
in the surface oxide film 21A by photolithography and etching. Thereby, the surface oxide film
21A is divided into the first insulating film 4 and the first sacrificial layer 23.
18-04-2019
7
[0022]
Next, as shown in FIG. 3B, SiN is deposited on the wafer W and the surface oxide film 21A by
PECVD (Plasma Enhanced Chemical Vapor Deposition) method, and this deposited layer is etched
back. Thus, the SiN film 24 is embedded in the circular groove 22. Thereafter, doped polysilicon
is deposited on the surface oxide film 21A and the SiN film by LPCVD (Low Pressure Chemical
Vapor Deposition) method. Then, the deposited layer of doped polysilicon is selectively removed
by photolithography and etching. Thereby, the diaphragm 7 and the plurality of support portions
8 are formed on the surface oxide film 21A and the SiN film 24.
[0023]
Then, SiO 2 is deposited on the entire area of the diaphragm 7, the support 8, the surface oxide
film 21 A, and the SiN film 24 by PECVD. Then, as shown in FIG. 3C, circular grooves 25 are
formed in the deposited layer of SiO 2 by photolithography and etching. Thus, the second
insulating film 5 is formed on the first insulating film 4, and the second sacrificial layer 26 is
formed on the first sacrificial layer 23. The diaphragm 7 is covered by the second sacrificial layer
26. Thereafter, the back plate 9 is formed on the second sacrificial layer 26 by the same method
as the method of forming the diaphragm 7. Further, the plurality of recesses 27 are formed in the
second sacrificial layer 26 by photolithography and etching.
[0024]
Thereafter, as shown in FIG. 3D, protective film 11 made of SiN is formed by PECVD so as to
collectively cover first insulating film 4, second insulating film 5, first sacrificial layer 23, and
second sacrificial layer 26. Is formed. The SiN film 24 is integrated with the protective film 11.
Then, the holes 14 are formed in the protective film 11 by photolithography and etching, and the
protective film 11 is removed from the holes 10 of the back plate 9.
[0025]
Next, an opening 28 is formed in the back surface oxide film 21B by photolithography and
18-04-2019
8
etching, and the silicon wafer W is etched through the opening 28 to form the through hole 3 in
the silicon wafer W. Thereafter, the etchant (for example, hydrofluoric acid) is supplied to the
inside of the protective film 11 through the through holes 3 and the holes 10 and 14 to remove
the first sacrificial layer 23 and the second sacrificial layer 26. Then, the back surface oxide film
21B is removed, and the silicon wafer W is cut into the substrates 2 to obtain the silicon
microphone 1 shown in FIG.
[0026]
As described above, in the silicon microphone 1, the through hole 3 is formed in the substrate 2,
and the diaphragm 7 is disposed to face the through hole 3. The diaphragm 7 is formed to have a
size smaller than that of the through hole 3 when viewed in the opposite direction to the through
hole 3. Therefore, the diaphragm 7 does not face the through hole peripheral portion 6 in the
direction orthogonal to the surface of the substrate 2, and the vibration width of the diaphragm 7
is not limited by the contact between the diaphragm 7 and the substrate 2. Therefore, the
diaphragm 7 is supported by a plurality of support portions 8 extending from the peripheral
edge thereof to the outside of the peripheral edge of the through hole 3. As a result, the
supporting strength of the diaphragm 7 is increased, so that the diaphragm 7 does not vibrate
excessively even if an excessive pressure is applied to the diaphragm 7. Thus, damage to the
diaphragm 7 and the support portion 8 due to excessive vibration of the diaphragm 7 can be
prevented.
[0027]
In the manufacturing process of the silicon microphone 1, after the first sacrificial layer 23 is
formed on the silicon wafer W (substrate 2), the diaphragm 7 and the support portion 8 are
formed on the first sacrificial layer 23, the silicon wafer W is penetrated. The holes 3 are formed,
and the etchant is supplied to the first sacrificial layer 23 through the through holes 3 to remove
the first sacrificial layer 23. Since the diaphragm 7 and the through hole peripheral portion 6 in
the silicon wafer W do not face each other, the etching solution can be efficiently supplied to the
first sacrificial layer 23. As a result, the first sacrificial layer 23 on the silicon wafer W can be
removed in a short time, and the time required for manufacturing the silicon microphone 1 can
be shortened.
[0028]
18-04-2019
9
The diaphragm 7 may be formed in a circular shape having the same diameter as the diameter of
the through hole 3 in a plan view. Further, the diaphragm 7 is not limited to a circular shape in a
plan view, and may be formed in an elliptical shape in a plan view or a polygonal shape in a plan
view. That is, the diaphragm 7 may be formed to have a size equal to or smaller than the size of
the through hole 3 in a plan view. Further, as shown in FIG. 4, the diaphragm 7 has its center
offset from the center of the through hole 3 in a plan view, and a portion thereof is orthogonal to
the through hole peripheral portion 6 (see FIG. 1) It may be opposed in the direction.
[0029]
As mentioned above, although embodiment of this invention was described, it is possible to give
various design change to the above-mentioned embodiment in the range of the matter described
in the claim. The present invention is not limited to silicon microphones, and can be widely
applied to pressure sensors and acceleration sensors that operate by detecting the amount of
change in capacitance.
[0030]
FIG. 1 is a schematic cross-sectional view showing a structure of a silicon microphone according
to an embodiment of the present invention. FIG. 2 is a schematic plan view of the diaphragm and
the support shown in FIG. FIG. 3A is a schematic cross-sectional view for explaining the method
of manufacturing the silicon microphone shown in FIG. FIG. 3B is a schematic cross-sectional
view showing the next step of FIG. 3A. FIG. 3C is a schematic cross-sectional view showing the
next step of FIG. 3B. FIG. 3D is a schematic cross-sectional view showing the next step of FIG. 3C.
FIG. 3E is a schematic cross-sectional view showing the next step of FIG. 3D. FIG. 4 is a schematic
plan view for explaining another embodiment (a mode in which the arrangement position of the
diaphragm is changed). FIG. 5 is a schematic cross-sectional view showing the structure of a
conventional silicon microphone.
Explanation of sign
[0031]
1 silicon microphone 2 substrate 3 through hole 7 diaphragm (vibration film) 8 support portion
18-04-2019
10
18-04-2019
11
Документ
Категория
Без категории
Просмотров
0
Размер файла
21 Кб
Теги
jp2010103701, description
1/--страниц
Пожаловаться на содержимое документа