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JP2009260884

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DESCRIPTION JP2009260884
An object of the present invention is to provide a sensitivity measuring device of a capacitance
type sensor which can measure sensitivity more simply than in the prior art and can reduce the
manufacturing cost, and a measuring method thereof. SOLUTION: A sensitivity measuring device
100 for a condenser microphone comprises a pressure container 101 provided on the side of a
diaphragm 11a of a microphone capsule 10, a pressure device 102 for pressurizing and
depressurizing the pressure in the pressure container 101, and a pressure device 102. 103, a
pressure gauge 104 for measuring the pressure in the pressurized container 101, a power supply
105 connected to the microphone capsule 10, a capacitance meter 106 for measuring the
capacitance of the microphone capsule 10, and various devices The pressure is adjusted to the
vibrating membrane 11a of the microphone capsule 10 by changing the pressure P in the
pressure vessel 101, and the amount of change in capacitance with respect to pressure is
provided. It has a configuration to measure sensitivity. [Selected figure] Figure 1
Apparatus and method for measuring sensitivity of capacitive sensor
[0001]
The present invention relates to a sensitivity measuring device of a capacitance type sensor
which operates by detecting a change amount of capacitance and a measuring method thereof.
[0002]
2. Description of the Related Art Conventionally, a capacitance type sensor manufactured using a
silicon semiconductor as a main material by semiconductor processing technology or
04-05-2019
1
micromachine processing technology is known.
The capacitance type sensor detects a change in pressure, acceleration or the like by converting
it into a change in capacitance. For example, the capacitive sensor includes a silicon microphone
that detects sound, a capacitive pressure sensor that detects pressure, and a capacitive
acceleration sensor that detects acceleration. Hereinafter, the background art according to the
present invention will be described by taking a silicon microphone as an example.
[0003]
The conventional silicon microphone has a counter electrode consisting of a vibrating film of
single crystal silicon and a fixed electrode plate, and is provided with a microphone capsule 50 as
shown in FIG. 6 (see, for example, Patent Document 1). The microphone capsule 50 includes a
vibrating film 51a provided on a silicon substrate 51 formed by processing a silicon wafer, a
fixed electrode plate 52 facing the vibrating film 51a with a gap therebetween, a vibrating film
51a and a fixed electrode plate 52. And an insulating film 53 for electrically insulating the same.
The vibrating film 51a and the fixed electrode plate 52 respectively have electrodes 54 and 55
for electrically connecting to an external device.
[0004]
In the microphone capsule 50, when the diaphragm 51a vibrates according to the sound
pressure, the capacitance between the diaphragm 51a and the fixed electrode plate 52 is
changed, and the amount of change in capacitance is detected by the external device. Sound
pressure is converted into an electrical signal.
[0005]
Conventionally, in order to evaluate the sensitivity of a silicon microphone, individual
microphone capsules are connected to an amplification circuit and housed in a package, and a
change in capacitance of the microphone capsule is output as a voltage, for example, in an
acoustic anechoic chamber In such a room for measurement, a method of measuring an output
voltage when a sound of a standard speaker is input is adopted.
Japanese Patent Application Laid-Open No. 2002-27595
04-05-2019
2
[0006]
However, as described above, the microphone capsule of the conventional silicon microphone is
collectively manufactured on the silicon wafer using the micromachine processing technology,
and the number thereof becomes enormous as hundreds of thousands. There is a problem that
the measurement process of the sensitivity of the above becomes complicated, and the
manufacturing cost increases.
[0007]
In addition, when sorting non-defective products and defective products within the same silicon
wafer, an amplifier circuit and a package are required including those used for defective
products, so that there is a problem that manufacturing cost increases.
As measures against this problem, it is conceivable to suppress an increase in manufacturing cost
by making the amplifier circuit and the package common. For example, it is conceivable to
package on a silicon wafer and connect to one amplification circuit while switching the
microphone capsule sequentially while measuring, but depending on the position of the
microphone capsule, the wiring from the microphone capsule to the amplification circuit
becomes long As a result, there is a problem that the sensitivity is significantly reduced and the
measurement becomes difficult. Furthermore, in this configuration, since the sound is diffracted
on the silicon wafer, the sound field is significantly different compared to the case of using an
actual microphone, and there is a problem that correct sensitivity data can not be obtained.
[0008]
The present invention has been made in view of the above-mentioned circumstances, and the
sensitivity can be measured more simply than in the prior art, and the sensitivity measuring
device of the capacitance type sensor and the manufacturing cost can be reduced. The purpose is
to provide a measurement method.
[0009]
The sensitivity measuring device of the capacitance type sensor according to the present
invention is a sensitivity measuring device of a capacitance type sensor including a movable
electrode plate displaced according to an external force, and a fixed electrode plate disposed
opposite to the movable electrode plate. An electrostatic pressure measuring means for adjusting
04-05-2019
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pressure to the movable electrode plate, an electrostatic capacity measuring means for
measuring an electrostatic capacitance between the movable electrode plate and the fixed
electrode plate, and the static electricity to the pressure And sensitivity measuring means for
measuring the sensitivity of the capacitive sensor from the amount of change in capacitance.
[0010]
With this configuration, the sensitivity measuring device of the capacitance type sensor
according to the present invention adjusts the pressure to the movable electrode plate and
measures the sensitivity from the amount of change of the capacitance with respect to the
pressure. It can be measured and the manufacturing cost can be reduced.
[0011]
Further, the sensitivity measuring device for a capacitance type sensor according to the present
invention comprises a voltage applying means for applying a voltage between the movable
electrode plate and the fixed electrode plate, and the sensitivity measuring means applies the
voltage. The sensitivity of the capacitive sensor is measured either in a state or in a state in which
the voltage is not applied.
[0012]
With this configuration, the sensitivity measuring device for a capacitance type sensor according
to the present invention can change the voltage when the capacitance or the amount of change in
capacitance with respect to the sound pressure is different between the case where the voltage is
applied and the case where the voltage is not applied. Since the capacitance can be measured in
the applied state, it is possible to obtain the correct sensitivity in consideration of the use
situation.
[0013]
Furthermore, in the sensitivity measuring device for a capacitance type sensor according to the
present invention, a pressure container having an opening, and the movable electrode plate are
disposed on the inner side of the pressure container so that the capacitance type sensor has the
opening. And a pressure gauge for measuring the pressure in the pressurized container, wherein
the pressurizing / depressing means is provided on the movable electrode plate by adjusting the
pressure in the pressurized container. It has a configuration that adjusts the pressure.
[0014]
With this configuration, the sensitivity measuring device of the capacitance type sensor
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according to the present invention adjusts the pressure to the movable electrode plate by
adjusting the pressure in the pressurized container, and the sensitivity is obtained from the
amount of change of the capacitance with respect to the pressure. Since the measurement is
performed, the sensitivity can be measured more simply than in the past, and the manufacturing
cost can be reduced.
[0015]
Further, in the sensitivity measuring device for a capacitance type sensor according to the
present invention, the sealing attachment means is for attaching a plurality of capacitance type
sensors to the opening in a sealing state, and the plurality of capacitance type sensors The sensor
selection means is provided to select one to be measured, and the capacitance measurement
means is configured to measure the capacitance of the selected capacitance type sensor.
[0016]
With this configuration, the sensitivity measuring device of the capacitance type sensor
according to the present invention can measure the capacitance of a plurality of capacitance type
sensors collectively, so that the sensitivity can be measured more simply than before. The
manufacturing cost can be reduced.
[0017]
Furthermore, in the sensitivity measuring device for a capacitance type sensor according to the
present invention, the plurality of capacitance type sensors are collectively formed on the same
semiconductor wafer using a semiconductor processing technology or a micromachine
processing technology. The sealing attachment means is configured to attach the semiconductor
wafer to the opening in a sealing state.
[0018]
With this configuration, the sensitivity measuring device of the capacitance type sensor of the
present invention can measure the capacitance of a large number of capacitance type sensors
formed at once on a semiconductor wafer at one time, so The sensitivity can be easily measured,
and the manufacturing cost can be reduced.
[0019]
Further, in the sensitivity measuring device for a capacitance type sensor according to the
present invention, the semiconductor wafer has the electrode of the movable electrode plate and
the electrode of the fixed electrode plate on the surface opposite to the surface on which the
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movable electrode plate is formed. The capacitance measuring means may include a probe
electrically connected to the electrode of the movable electrode plate and the electrode of the
fixed electrode plate.
[0020]
With this configuration, the sensitivity measuring device of the capacitance type sensor
according to the present invention can easily measure the capacitance of a large number of
capacitance type sensors formed in a batch on a semiconductor wafer using a probe. Therefore,
the sensitivity can be measured more simply than in the prior art, and the manufacturing cost
can be reduced.
[0021]
Furthermore, the sensitivity measuring device for a capacitance type sensor according to the
present invention includes a computer for outputting sensitivity data of the capacitance type
sensor, and the computer controls pressure / decompression control means for controlling the
operation of the pressure / decompression means Pressure data receiving means for receiving
pressure data in the pressurized container from the pressure gauge, sensor selection control
means for controlling the operation of the sensor selection means, and capacitance of the
selected capacitance type sensor And capacitance data receiving means for receiving data from
the capacitance measuring means.
[0022]
With this configuration, the sensitivity measuring device of the capacitance type sensor of the
present invention can automatically measure the capacitance using a computer, so that the
sensitivity can be measured more simply than in the past, and the manufacturing cost Can be
reduced.
[0023]
The sensitivity measuring method of the capacitance type sensor according to the present
invention is a sensitivity measuring method of a capacitance type sensor comprising a movable
electrode plate displaced according to an external force, and a fixed electrode plate disposed
opposite to the movable electrode plate. The step of measuring the capacitance between the
movable electrode plate and the fixed electrode plate by adjusting the pressure to the movable
electrode plate, and the amount of change of the capacitance with respect to the pressure And
measuring the sensitivity of the capacitive sensor.
04-05-2019
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[0024]
With this configuration, the method of measuring the sensitivity of the capacitance type sensor
according to the present invention adjusts the pressure to the movable electrode plate and
measures the sensitivity from the amount of change in capacitance with respect to the pressure.
It can be measured and the manufacturing cost can be reduced.
[0025]
The present invention can provide a sensitivity measuring device of capacitance type sensor and
a measuring method thereof, which has an effect that the sensitivity can be measured more
simply than in the past and the manufacturing cost can be reduced. is there.
[0026]
Before describing the embodiment of the present invention, a method of measuring the
sensitivity of a condenser microphone, which is one of the capacitive sensors, will be described.
FIG. 7 is a diagram showing a measurement method of a conventional condenser microphone,
and the microphone capsule of the condenser microphone is indicated by a symbol of a
condenser.
[0027]
In FIG. 7, the microphone capsule 61 of the condenser microphone has a vibrating film 61a and a
fixed electrode plate 61b.
A power source 63 is connected to the fixed electrode plate 61b of the microphone capsule 61
via a high resistance 62, and a voltage V0 is applied.
At this time, the displacement of the vibrating membrane 61 a caused by the sound pressure P is
indicated by w.
Assuming that the voltage of the microphone capsule 61 is V, the sensitivity S of the condenser
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microphone is defined by [Equation 1] (literature "" Electro-Acoustic Vibrations ", p. 152,
Nishimaki, Corona Co.").
[0028]
[0029]
In the conventional method of measuring a condenser microphone, a condenser 64 with a direct
current cut and an amplification circuit 65 are connected to the microphone capsule 61 so that a
voltage change of the microphone capsule 61 can be taken out as an output. The sound pressure
was applied by the following equation, and the sensitivity was evaluated by [Equation 1] by
measuring the voltage output at that time.
[0030]
Here, [Equation 1] is transformed into [Equation 2].
[0031]
[0032]
In [Equation 2], it is assumed that the air gap length of the microphone capsule 61 in the state
where no sound pressure is applied is w 0, and the electric field in the air gap of the microphone
capsule 61 is uniform.
[0033]
Further, assuming that the capacitance of the microphone capsule 61 is C, the capacitance C is
represented by [Equation 3].
Here, A represents the area of the vibrating film 61a, and ε 0 represents the dielectric constant
of vacuum.
[0034]
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[0035]
Here, when the value of | dC / dP | is calculated, [Equation 4] is obtained.
[0036]
[0037]
The sensitivity S is expressed by [Equation 5] from [Equation 2] and [Equation 4].
[0038]
[0039]
The sensitivity S is expressed by the capacitance C of the microphone capsule, the change
amount | dC / dP | of the capacitance C with respect to the sound pressure P, and the voltage V0
applied to the microphone capsule by [Equation 5]. I understand.
Among them, since the voltage V0 is known, if the capacitance C of the microphone capsule and
the change amount of the capacitance C with respect to the sound pressure P are known, the
sensitivity S can be obtained.
Therefore, an apparatus and method for measuring these values will be described below as an
embodiment of the present invention with reference to the drawings.
[0040]
First Embodiment In the first embodiment of the present invention, an example in which the
sensitivity measuring device for a capacitance type sensor according to the present invention is
applied to a sensitivity measuring device for a condenser microphone will be described.
[0041]
FIG. 1A is a view conceptually showing the sensitivity measuring device for a condenser
microphone in the present embodiment, and the microphone capsule is indicated by a symbol of
04-05-2019
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a condenser.
[0042]
As shown in FIG. 1A, the sensitivity measuring device 100 for a condenser microphone according
to the present embodiment includes the pressure container 101 provided on the vibrating
membrane 11a side of the microphone capsule 10 and the pressure in the pressure container
101. A pressurizing device 102 for pressurizing and depressurizing, a pump 103 for driving the
pressurizing device 102, a pressure gauge 104 for measuring the pressure in the pressurized
container 101, a power supply 105 connected to the microphone capsule 10, and electrostatics
of the microphone capsule 10. A capacity meter 106 for measuring the capacity, and a personal
computer (hereinafter referred to as "PC") for controlling each device and collecting various data.
And 107).
[0043]
FIG. 1B is a view conceptually showing a cross section of the microphone capsule 10 and a
partial cross section of the pressure container 101.
The microphone capsule 10 includes a vibrating membrane 11 a provided on the frame 11, a
fixed electrode plate 12, and a spacer 13 provided between the vibrating membrane 11 a and the
fixed electrode plate 12.
The vibrating film 11a constitutes a movable electrode plate according to the present invention.
[0044]
A through hole is formed in the container bottom 101 a of the pressurized container 101.
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A sealing material 101b is provided on the top of the frame 11 of the microphone capsule 10,
and the microphone capsule 10 is fixed to the pressure container 101 so as to cover the through
hole of the container bottom 101a.
Here, the vibrating membrane 11a is inside the pressure vessel 101, and the fixed electrode plate
12 is in contact with the outside air.
As the sealing material 101b, for example, packing such as an O-ring or a sealing material made
of resin can be used.
In addition, the sealing material 101b comprises the sealing attachment means which concerns
on this invention.
[0045]
The pressurizer 102 includes, for example, a cylinder so that the pressure P in the pressure
container 101 can be changed.
The pump 103 is connected to the pressurizer 102 and the PC 107, and is configured to
pressurize or depressurize the pressurized container 101 according to a control signal from the
PC 107.
The pressurizer 102 and the pump 103 constitute a pressurizing and depressurizing unit
according to the present invention.
Further, regardless of the control signal from the PC 107, pressure or pressure reduction may be
performed manually.
[0046]
The pressure gauge 104 measures the pressure P in the pressurized container 101, and outputs
measurement data to the PC 107 based on the control signal from the PC 107.
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[0047]
The power source 105 applies a voltage V 0 to the fixed electrode plate 12 side of the
microphone capsule 10.
The power source 105 constitutes a voltage application unit according to the present invention.
[0048]
The capacitance meter 106 is connected to the vibrating membrane 11 a of the microphone
capsule 10 and the fixed electrode plate 12 to measure the capacitance C of the microphone
capsule 10.
Further, the capacitance meter 106 is configured to output the measured data of the measured
capacitance C to the PC 107.
The capacitance meter 106 constitutes a capacitance measuring unit according to the present
invention.
[0049]
The PC 107 includes, for example, a CPU, a RAM, a ROM, an interface (GPIB, RS232, USB, and the
like), a disk drive, a display, a printer, and the like, and is connected to each device.
The PC 107 constitutes a sensitivity measuring unit according to the present invention.
[0050]
Here, the PC 107 controls the operation of the pressurizer 102 and the pump 103 as
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pressurizing and depressurizing means, pressure data receiving means for receiving pressure
data in the pressure vessel 101 from the pressure gauge 104, and It has a function as
capacitance data receiving means for receiving capacitance data in the capacitance type sensor
from the capacitance measuring means.
The PC 107 can acquire capacitance measurement data in accordance with a program that
controls the operation of the connected device.
[0051]
The sensitivity measuring device 100 of the condenser microphone in the present embodiment is
configured as described above, and measures the capacitance C of the microphone capsule 10
while changing the pressure P in the pressure container 101.
An example of the measurement result is shown in FIG.
Since the capacitance C and the variation of the capacitance C with respect to the pressure P
(determined as the slope of the approximate straight line in the measurement result shown in
FIG. 2) are obtained from this measurement result, these data and the voltage V0 The sensitivity
is obtained from [Equation 5].
[0052]
Regarding the voltage V0 applied to the microphone capsule 10, when the capacitance C and the
variation amount | dC / dP | of the capacitance C with respect to the sound pressure P differ
between the case where the voltage is applied and the case where the voltage is not applied, It is
preferable to measure the capacitance C while applying a voltage in order to obtain the correct
sensitivity.
On the other hand, if it can be considered that the capacitance C and the amount of change of the
capacitance C with respect to the sound pressure P do not change between applying and not
applying the same voltage, it is necessary to apply the voltage. However, the configuration of the
measurement system can be simplified.
04-05-2019
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[0053]
As the capacitance meter 106, it is preferable to use, for example, a minute capacitance meter
using a high accuracy capacitance bridge because it is necessary to measure a minute
capacitance.
In the measurement, although the wiring from the capacitance meter 106 to the microphone
capsule 10 has a capacitance component, in the high-precision minute capacitance meter, the
effect of the wiring capacitance is eliminated by performing calibration before the measurement,
and the microphone capsule Capacitance C of 10 can be measured accurately.
[0054]
As described above, according to the sensitivity measuring device 100 for a condenser
microphone in the present embodiment, the pressure is applied to the vibrating film 11a of the
microphone capsule 10, and the sensitivity is measured from the amount of change in
capacitance with respect to pressure. Therefore, as in the conventional measurement, a dedicated
amplifier circuit or package is not necessary, and there is no need to perform a difficult
measurement such as inputting the sound of a standard speaker in an acoustic anechoic
chamber, for example, which increases time and cost. The sensitivity can be easily determined.
[0055]
Therefore, the sensitivity measuring device 100 for a condenser microphone according to the
present embodiment can measure the sensitivity more simply than in the conventional case, and
the manufacturing cost can be reduced.
[0056]
In the above embodiment, although the sensitivity measuring device of the condenser
microphone has been described as an example, the present invention is not limited to this, and
the electrostatic which operates by detecting the amount of change of the electrostatic capacity
The present invention can be applied to the sensitivity measuring device of a capacitive sensor,
and the same effect can be obtained.
[0057]
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Second Embodiment FIG. 3 and FIG. 4 are diagrams schematically showing a sensitivity
measuring device according to a second embodiment of the present invention.
The present embodiment is for evaluating the sensitivity of a plurality of microphone capsules,
and will be described by taking a silicon microphone sensitivity measuring device as an example.
The same components as those of the first embodiment are denoted by the same reference
numerals and the description thereof will be omitted.
[0058]
As shown in FIG. 3, the sensitivity measuring device 200 of the silicon microphone in the present
embodiment is electrically connected to the pressurizing container 201, the pressurizing device
102, the pump 103, the pressure gauge 104, and the plurality of microphone capsules 20. The
switch element 202 connected, the capacitance meter 203, and the PC 204 are provided.
Here, the plurality of microphone capsules 20 are collectively formed on the silicon wafer 30.
[0059]
A through hole is formed in the container bottom surface 201 a of the pressurized container
201, and the disk-shaped silicon wafer 30 is connected to the container bottom surface 201 a via
the sealing material 201 b so as to cover the through hole. The capacitance C of the sensor can
be measured.
As the sealing material 201b, for example, packing such as O-ring or a sealing material made of
resin can be used.
In addition, the sealing material 201b comprises the sealing attachment means which concerns
on this invention.
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[0060]
In detail, the sensitivity measurement apparatus 200 of the silicon microphone is configured as
shown in FIG.
FIG. 4A is a view of the microphone capsule 20 as viewed from the fixed electrode plate 22 side,
and FIG. 4B is a view conceptually showing a cross section of the silicon wafer 30 and a partial
cross section of the pressure container 201. is there.
In addition, in order to simplify the illustration, the number of microphone capsules 20 is shown
as a configuration of 2 rows × 2 columns = 4 in FIG.
[0061]
As shown in FIG. 4B, the microphone capsule 20 includes a vibrating membrane 21, a fixed
electrode plate 22 in which a through hole 22a is formed, and a spacer 23 provided between the
vibrating membrane 21 and the fixed electrode plate 22. And an electrode 24 connected to the
vibrating film 21 and an electrode 25 formed on the fixed electrode plate 22.
The vibrating film 21 constitutes a movable electrode plate according to the present invention.
[0062]
Further, as shown in FIGS. 4A and 4B, a probe 205 is electrically connected to an electrode 24
formed on one surface of the silicon wafer 30 and on the vibrating film 21 side of the
microphone capsule 20. A plurality of probes 206 are electrically connected to the electrodes 25
formed on the fixed electrode plate 22 of the microphone capsule 20 for each microphone
capsule 20. Here, the probe 205 is connected to the ground side of the capacitance meter 203
(see FIG. 3), and the plurality of probes 206 are connected to the switch element 202 (see FIG. 3).
Thereby, by measuring the capacitance value between the probe 205 and the probe 206, the
capacitance C of the microphone capsule 20 can be obtained.
04-05-2019
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[0063]
In the microphone capsule 20 having the configuration shown in FIG. 4, it is assumed that the
vibrating membrane 21 has the same potential as the silicon wafer 30 and the electrode 24 on
the vibrating membrane 21 side is present around the fixed electrode plate 22. The present
invention is not limited to this, and the position at which the probe contacts can be variously
changed according to the structure of the vibrating membrane and the fixed electrode plate, the
structure and the arrangement of the electrodes, and the like.
[0064]
In addition to using the probes 205 and 206, for example, a method using a bump or a method
using a wire such as gold or aluminum can be used as a method of electrically connecting.
However, it is desirable that the electrical connection causes less physical damage to the
microphone capsule 20. Further, as the input to the capacitance meter 203, there are, for
example, a method of inputting the whole number of the microphone capsules 20 as parallel
signals, and a method of converting parallel signals into serial signals by the switch element 202
and then sequentially measuring them.
[0065]
Returning to FIG. 3, the switch element 202 is constituted by, for example, a multiplexer, and is
connected to the PC 204 and the capacitance meter 203, and connects the microphone capsule
20 to be measured and the capacitance meter 203 according to the control signal from the PC
204. ing. The switch element 202 constitutes a sensor selection unit according to the present
invention.
[0066]
The capacitance meter 203 is internally provided with a power supply (not shown) for outputting
the voltage V0, and according to a control signal from the PC 204, the voltage V0 is applied to
the microphone capsule 20 or not applied either. The capacitance C is measured, and the
04-05-2019
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measured data is output to the PC 204. The capacitance meter 203 constitutes a capacitance
measurement unit and a voltage application unit according to the present invention.
[0067]
The PC 204 has a function as a sensor selection control unit that controls the operation of the
switch element 202 as a sensor selection unit in addition to the function in the first embodiment.
The PC 204 constitutes a sensitivity measurement unit according to the present invention.
[0068]
Next, an example of a method of automatically measuring a large number of microphone
capsules 20 collectively formed on a silicon wafer 30 will be described with reference to FIGS. 3
and 5.
[0069]
First, the PC 204 controls the pressurizer 102 and the pump 103 so that the pressure in the
pressure container 101 becomes P1.
Next, the pressure in the pressurized container 101 is fixed at pressure Pl, and all the
microphone capsules 20 are measured.
[0070]
Specifically, for example, as shown in FIG. 5A, under the control of the PC 204, the switch
element 202 is made to select the microphone capsule M1, and the capacitance Cll at the
pressure Pl of the microphone capsule M1 is measured by the capacitance meter 203. .
Subsequently, the switch element 202 is made to select the microphone capsule M2, and the
capacitance C21 at the pressure Pl of the microphone capsule M2 is measured by the
capacitance meter 203. Subsequently, the microphone capsule 20 is sequentially selected by the
switch element 202, and each capacitance C at the pressure P1 is measured.
04-05-2019
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[0071]
Next, the pressure of the pressurized container 201 is set to P2 by the PC 204, the switch
element 202 is made to select the microphone capsule M1, and the capacitance C12 at the
pressure P2 of the microphone capsule M1 is measured by the capacitance meter 203. Next, the
switch element 202 is made to select the microphone capsule M2, and the capacitance C22 at
the pressure P2 of the microphone capsule M2 is measured by the capacitance meter 203.
Similarly, measurement is performed on all the microphone capsules 20 while switching the
microphone capsule 20 and the pressure P.
[0072]
From the measurement data shown in FIG. 5A, the relationship between the capacitance C and
the amount of change of the capacitance C with respect to the pressure P can be obtained for
each of the microphone capsules 20. An example of the relationship between the capacitance
value and the pressure is shown in FIG. 5 (b). The graph shown in FIG. 5B can be automatically
created by the PC 204 by a predetermined program. From the inclination of the approximate
straight line in this graph, the sensitivity of the silicon microphone using the microphone capsule
20 can be obtained. Also, it is possible to automatically output the sensitivity data of each
microphone capsule 20 by the PC 204.
[0073]
As described above, according to the sensitivity measuring apparatus 200 for a silicon
microphone in the present embodiment, the pressure is simultaneously applied to the vibrating
films 21 of the plurality of microphone capsules 20, and the sensitivity is measured from the
amount of change in capacitance with respect to pressure. Therefore, even when the amount of
the microphone capsule 20 is very large such as several hundred to several thousand, it is
possible to measure the sensitivity of the complete or many microphone capsules 20. In addition,
when sorting non-defective products and defective products within the same silicon wafer, it is
possible to sort only by this capacitance measurement, so there is no need to carry out any
subsequent mounting and evaluation steps for defective products, and time and It is possible to
significantly reduce the cost.
[0074]
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19
Therefore, the sensitivity measuring device 200 of the silicon microphone according to the
present embodiment can measure the sensitivity more simply than in the conventional case, and
the manufacturing cost can be reduced.
[0075]
In the above embodiment, although the microphone capsule of the silicon microphone has been
described as the target of the sensitivity measurement, the present invention is not limited to
this, and a condenser microphone using a material such as metal, ceramic or resin, ECM (Electret
condenser microphone) or the like may be a measurement target.
When the object to be measured is not a microphone capsule of a silicon microphone, a plurality
of individually formed microphone elements are disposed on a jig, a support substrate, or the like
even if the elements such as the microphone capsule are not formed collectively. By setting the
jig and the substrate in the same manner as the above-described silicon wafer, measurement can
be performed collectively.
[0076]
As described above, the sensitivity measuring device for capacitance type sensor according to the
present invention and the measuring method thereof have the effect of being able to measure the
sensitivity more simply than in the prior art and reducing the manufacturing cost. In particular, it
is useful for the purpose of evaluating the sensitivity of a plurality of microphone capsules.
[0077]
Block diagram conceptually showing the configuration of the first embodiment of the sensitivity
measurement device for a condenser microphone according to the present invention In the first
embodiment of the sensitivity measurement device for a condenser microphone according to the
present invention, capacitance C and 4 is a diagram showing the relationship between the
amount of change in electrostatic capacitance C with the pressure P. A block diagram
conceptually showing the configuration in the second embodiment of the sensitivity measuring
device for silicon microphones according to the present invention In the second embodiment of
the sensitivity measuring device, a diagram conceptually showing the configuration around the
silicon wafer In the second embodiment of the silicon microphone sensitivity measuring device of
the present invention Figure for explaining an example of a microphone capsule included in a
conventional silicon microphone It shows a measuring method
04-05-2019
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Explanation of sign
[0078]
DESCRIPTION OF REFERENCE NUMERALS 10 condenser microphone microphone capsule 11
frame 11 a diaphragm (movable electrode plate) 12 fixed electrode plate 13 spacer 20 silicon
microphone microphone capsule 21 diaphragm (movable electrode plate) 22 fixed electrode
plate 22 a through hole 23 spacer 24 electrode (movable electrode) Plate electrode 25 electrode
(electrode of fixed electrode plate) 30 silicon wafer (semiconductor wafer) 100 sensitivity
measuring device of condenser microphone 101, 201 pressurized container 101a, 201a
container bottom 101b, 201b sealing material (sealed attachment means) 102 Pressure gauge
(pressure adjustment means) 103 Pump (pressure adjustment means) 104 Pressure gauge 105
Power supply (voltage application means) 106 Capacitance measurement means (capacitance
measurement means) 107, 204 PC (computer, sensitivity measurement means) 200 Sensitivity
measurement of silicon microphone Location 202 switching elements (sensor selection means)
203 capacity meter (capacitance measuring means, voltage applying means) 205 and 206 probes
04-05-2019
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