JP2001215161A - Broadband capacitive vacuum sensor - Google Patents

Abstract

(57) [Summary] [Problem] A pair of diaphragm electrodes and a fixed electrode facing each other at an interval are arranged inside, and the diaphragm electrode and the fixed electrode due to displacement of the diaphragm electrode according to a gas pressure to be measured. Capacitance type vacuum sensor that measures gas pressure from the change in capacitance between the pressure measurement and the pressure measurement in a wider range compared to the conventional type without significantly changing the structure of the conventional capacitance type vacuum sensor Is possible. SOLUTION: The problem has been solved by sealing a space between a diaphragm electrode (4) and a fixed electrode (5) with a pressure higher than a minimum measurement pressure. Further, by applying a DC voltage to the fixed electrode (5), the problem is solved in that the amount of displacement of the diaphragm electrode (4) in the direction away from the fixed electrode (5) can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum sensor for measuring a pressure in a vacuum device used for manufacturing electronic parts and semiconductor products, and more particularly, to a capacitance type sensor whose pressure measurement range is widened. It relates to a vacuum sensor.

[0002]

2. Description of the Related Art In the process of manufacturing electronic parts and semiconductor products, a process of forming or etching a thin film in a vacuum apparatus is indispensable. At this time, the process is usually carried out while the pressure in the vacuum device is kept constant, and a capacitance type vacuum sensor is often used as a pressure measuring means in the vacuum device.

FIG. 6 shows an example of a conventional capacitive vacuum sensor. The conventional capacitive vacuum sensor has a chamber (reference pressure chamber 1) for providing a reference pressure inside the sensor, and the reference pressure chamber 1 includes a region 3 communicating with the internal space of the vacuum device 2 and an elastic diaphragm. The electrodes are partitioned by electrodes (diaphragm electrodes 4), and a fixed electrode 5 is arranged on the insulating substrate 9 so as to face the diaphragm electrodes 4.

When there is a pressure difference between the reference pressure chamber 1 and the region 3 communicating with the internal space of the vacuum device 2, the diaphragm electrode 4 made of an elastic diaphragm is displaced according to the pressure difference. Since the capacitance between the diaphragm electrode 4 and the fixed electrode 5 is inversely proportional to the distance between the two, this electric information is transmitted to the electric circuit 6 through the conducting wire 7, and the capacitance is converted into a voltage or a current and output outside the sensor. Thus, the gas pressure in the region 3 communicating with the internal space of the vacuum device 2 can be measured.

Here, in the conventional capacitance type vacuum sensor, a getter 10 is disposed inside the reference pressure chamber 1, whereby gas remaining in the reference pressure chamber 1 is adsorbed, and The internal space of No. 1 was sealed with a pressure as low as or lower than the lower limit pressure for measurement.

Accordingly, when the pressure in the region 3 communicating with the internal space of the vacuum device 2 is as low as the pressure in the reference pressure chamber 1, the diaphragm electrode 4 connects the internal space of the reference pressure chamber 1 and the vacuum device 2. Since the same force is applied in the opposite direction from both of the communicating regions 3, a flat state is obtained in which almost no displacement occurs. When the pressure in the region 3 communicating with the internal space of the vacuum device 2 gradually increases, the diaphragm electrode 4 is gradually displaced toward the fixed electrode 5 in response thereto, and finally the amount of displacement of the diaphragm electrode 4 is reduced. An accurate pressure is measured, for example, the amount of change according to the pressure in the region 3 communicating with the internal space of the vacuum device 2 is not displayed (proportional limit), or the diaphragm electrode 4 comes into contact with the fixed electrode 5. You will not be able to do it.

[0007] The lower limit pressure for measurement is the difference between the pressure in the reference pressure chamber 1 and the gas pressure in the region 3 communicating with the internal space of the vacuum device 2, and the displacement of the diaphragm electrode 4 according to this pressure difference. It is the critical pressure on the lower limit side of the pressure region that has a proportional relationship. For example, the measurement lower limit pressure of a high-sensitivity capacitive vacuum sensor is about 10 ⁻² Pa.

[0008]

In a capacitive vacuum sensor, a diaphragm electrode (elastic diaphragm electrode) inside the vacuum sensor is displaced in accordance with the gas pressure to be measured, and accordingly, the insulating substrate is opposed to the diaphragm electrode. This is a vacuum sensor based on the principle of measuring the pressure of a gas by utilizing the change in the capacitance between the fixed electrode and the diaphragm electrode installed above.

Here, the diaphragm electrode is not always displaced in a fixed relationship with the gas pressure measured by the vacuum sensor. That is, when the amount of displacement of the diaphragm electrode is usually within 60% of the thickness of the diaphragm electrode, the diaphragm electrode is displaced in proportion to the gas pressure measured by the vacuum sensor, but the diaphragm electrode is displaced more than that. In such a case, the diaphragm electrode does not displace in proportion to the gas pressure measured by the vacuum sensor (proportional limit). That is,
The pressure range in which the capacitance type vacuum sensor operates normally is that the displacement amount of the diaphragm electrode is 60 times the thickness of the diaphragm electrode.
% Only in a limited pressure range within%.

Further, since the reference pressure chamber inside the conventional capacitance type vacuum sensor is sealed with a low pressure equal to or lower than the measurement lower limit pressure, the displacement area of the diaphragm electrode is 0 to the thickness of the diaphragm electrode. It is limited to 60%.

[0011] The present invention provides a wide-band electrostatic sensor capable of easily measuring a wide range of pressures as compared with a conventional capacitive vacuum sensor without greatly changing the structure of the conventional capacitive vacuum sensor. It is an object to provide a capacitive vacuum sensor.

[0012]

In order to achieve the above object, the present invention provides a pressure sensor for sealing a space inside a reference pressure chamber of a capacitance type vacuum sensor which is higher than a measurement lower limit pressure. It is. As a result, it is possible to widen the pressure range in which the diaphragm electrode is displaced in proportion to the gas pressure measured by the vacuum sensor.

That is, when the pressure of the gas measured by the capacitive vacuum sensor is lower than the sealing pressure inside the reference pressure chamber of the vacuum sensor, the diaphragm electrode is displaced away from the fixed electrode. Is less than 60% of the thickness of the diaphragm electrode, the diaphragm electrode is displaced in proportion to the gas pressure measured by the vacuum sensor, and as a result, an accurate gas pressure can be measured.

Therefore, when the pressure of the gas measured by the capacitive vacuum sensor is equal to the lower limit pressure of the vacuum sensor (at this time, the diaphragm is displaced away from the fixed electrode), the amount of displacement is small. 60 of the thickness of the diaphragm electrode
If the sealing pressure inside the reference pressure chamber of the vacuum sensor is set so as to be%, accurate pressure can be measured even at the measurement lower limit pressure. With this configuration, it is possible to accurately measure the pressure from the pressure sealing the space inside the reference pressure chamber of the capacitance type vacuum sensor to the measurement lower limit pressure.

Next, when the pressure of the gas measured by the vacuum sensor is gradually increased from this state, the displacement of the diaphragm electrode is reduced accordingly, and the pressure of the gas measured by the vacuum sensor is reduced by the pressure of the vacuum sensor. At the time when the pressure becomes equal to the sealing pressure in the reference pressure chamber, it finally becomes flat.

Thereafter, when the pressure inside the vacuum apparatus is further increased, the diaphragm electrode starts to be displaced in the direction of the fixed electrode, and finally the diaphragm electrode is displaced in proportion to the gas pressure measured by the vacuum sensor. Proportional limit (the amount of displacement of the diaphragm electrode is 60 times the thickness of the diaphragm electrode)
%).

That is, the displacement area of the diaphragm electrode which can be used for pressure measurement by using the concept of the present invention is -60% to + 60% of the thickness of the diaphragm electrode, that is, the displacement amount in the direction in which the diaphragm electrode approaches the fixed electrode. Is 60% of the thickness of the diaphragm electrode from 60% of the thickness of the diaphragm electrode to 60% of the thickness of the diaphragm electrode, and the displacement of the diaphragm electrode in the direction away from the fixed electrode is wider than that of the conventional capacitive vacuum sensor. It becomes possible.

In the above description, if the pressure of the gas measured by the capacitance type vacuum sensor is lower than the sealing pressure inside the reference pressure chamber of the vacuum sensor, the diaphragm electrode is displaced away from the fixed electrode. The limit for accurately measuring pressure is until the displacement amount reaches 60% of the thickness of the diaphragm electrode (proportional limit).

However, the present invention makes it possible to control the amount of displacement of the diaphragm electrode in the direction away from the fixed electrode by applying a DC voltage to the fixed electrode, and to reach the state of the proportional limit field as described above. Further, even when the pressure of the gas measured by the capacitance type vacuum sensor decreases, accurate gas pressure measurement can be performed. In other words, when the state of the proportional limit is reached,
By applying a DC voltage to the fixed electrode, the diaphragm electrode is attracted to the fixed electrode side by electrostatic attraction, and the displacement of the diaphragm electrode is reduced. It is possible to continue accurate pressure measurement even if the pressure of the gas to be measured further decreases. With such a configuration, it is possible to further lower the measurement lower limit pressure at which the capacitance-type vacuum sensor can measure.

That is, the broadband capacitive vacuum sensor proposed by the present invention has a pair of opposed diaphragm electrodes and fixed electrodes spaced apart from each other, and the diaphragm electrodes correspond to the gas pressure to be measured. In a capacitance-type vacuum sensor that measures gas pressure from a change in capacitance between the diaphragm electrode and the fixed electrode due to displacement of
A space between the diaphragm electrode and the fixed electrode is sealed at a pressure higher than the lower limit pressure for measurement.

Further, in another broadband capacitive vacuum sensor proposed by the present invention, the displacement of the diaphragm electrode in the direction away from the fixed electrode has a maximum displacement of 60% or less of the thickness of the diaphragm electrode. The pressure for sealing the space between the diaphragm electrode and the fixed electrode is set so that

Still another broadband capacitive vacuum sensor proposed by the present invention is the broadband capacitive vacuum sensor described above, wherein the diaphragm electrode is separated from the fixed electrode by applying a DC voltage to the fixed electrode. The amount of displacement in the direction to go away can be controlled.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the description of the embodiments of the present invention, first, how the pressure of a gas measured by a capacitance type vacuum sensor displaces a diaphragm electrode will be described.

For example, assuming a rectangular diaphragm electrode having a side length of a, it is assumed that the pressure in the reference pressure chamber inside the capacitive vacuum sensor is kept at an extremely high degree of vacuum near zero.

In the conventional capacitive vacuum sensor having such a structure, the displacement W of the diaphragm electrode is expressed by the following equation: W = a ⁴ P · [1− (2 × / a) ² ] · [1- ( 2
y / a) ² ] ² · {0.02023 + 0.0053
5 [(2x / a) ² + (2y / a) ² ] +0.00
625 ^(2x / a) represented by ^{2 · (2y / a) 2} } / 16D [ Equation ^{2] D = Eh 3/12} (1-ν 2).

Here, P is the gas pressure measured by the vacuum gauge sensor, E is the Young's modulus of the diaphragm electrode material, ν is the Poisson's ratio of the diaphragm electrode material, h is the thickness of the diaphragm electrode, and x and y are the diaphragm electrodes. Are the coordinates of the plane position on the diaphragm electrode when the center is taken as the origin.

Here, the displacement amount W _{0 at} the center of the diaphragm electrode, that is, at the position of x = y = 0, is expressed by the following [Equation 1].
Substituting x = y = 0, a [Equation ^{_{3] W 0 = a 4 P}} · 0.02023 / 16D.

Here, in the case of a nickel-chromium-iron based alloy Inconel (an alloy manufactured by INCO), which is often used in a conventional capacitive vacuum sensor, Young's modulus E = 20 × 1
0 ^{1 0} Pa, Poisson's ratio [nu = 0.3, 2 cm in length of one side of the rectangular diaphragm electrode, when 50μm thickness, displacement of the diaphragm electrode central Expression _4] W 0 = 8.8 × 10 ⁻⁸ P (m).

[0029] FIG. 4 is a graph capacitive vacuum sensor showing the relation between the displacement amount W ₀ of the pressure P and the diaphragm electrode central portion of the gas to be measured from the equation 4]. Since the thickness of the diaphragm electrode is 50 μm, the displacement of the diaphragm electrode corresponding to 60% of the thickness is 30 μm, and the gas pressure measured by the capacitive vacuum sensor at that time is about 340 Pa from [Equation 4]. It is.

In other words, in the case of this conventional capacitance type vacuum sensor, the pressure range in which accurate pressure can be measured is 0 to 340.
It turns out that it is Pa.

Next, an embodiment of the present invention will be described with reference to FIG. 1. The capacitive vacuum sensor shown in FIG. 1 is structurally different from the conventional capacitive vacuum sensor shown in FIG. Is the point at which the getter 10 does not exist and the pressure inside the reference pressure chamber 1, that is, the pressure at which the space between the diaphragm electrode 4 and the fixed electrode 5 is sealed is the lower limit pressure of the vacuum sensor. Is higher than that.

At this time, as a gas for sealing the inside of the reference pressure chamber 1 at a certain pressure, an inert gas such as Ar or N _{2 is used.}
Can be used. However, when gas leakage from the reference pressure chamber 1 is concerned, Xe having a large atomic size is used.
It is preferable to use such as. Here, for example, in the case of the capacitive vacuum sensor of the present invention having a rectangular Inconel diaphragm electrode 4 having the same size as that described above, that is, a side of 2 cm and a thickness of 50 μm, the sealing inside the reference pressure chamber 1 is performed. When the pressure is set to 340 Pa, when the pressure of the gas measured by the sensor is lower than 340 Pa, the diaphragm electrode 4 is displaced away from the fixed electrode 5 (FIG. 5).
(A)). However, even if the gas pressure outside the sensor is infinitely close to 0, the difference between the internal pressure of the reference pressure chamber 1 received by the diaphragm electrode 4 and the pressure of the gas measured by the vacuum sensor is 340 Pa at the maximum. The displacement of the diaphragm electrode 4 is 30 μm,
Is within a range proportional to the gas pressure measured by the vacuum sensor.

On the other hand, when the gas pressure outside the sensor is increased, the force for pushing the diaphragm electrode 4 toward the inside of the reference pressure chamber 1 is increased, and the gas pressure outside the sensor is 340 Pa.
That is, when the sealing pressure is equal to the sealing pressure inside the reference pressure chamber 1, the diaphragm electrode 4 becomes flat (FIG. 5B).

Further, the gas pressure outside the sensor is increased.
When the pressure reaches 80 Pa, the diaphragm electrode 4 is displaced by 30 μm in a direction approaching the fixed electrode 5 (FIG. 5C),
At a higher pressure, the amount of displacement of the diaphragm electrode 4 is not proportional to the gas pressure outside the sensor, so that accurate gas pressure measurement cannot be performed.

However, the measurable pressure range is 0 to
It is 680 Pa, which enables measurement in a pressure region twice as large as that of a conventional capacitance vacuum sensor.

In this embodiment, when the size of one side of the rectangular diaphragm electrode 4 is 2 cm, the thickness is 50 μm, and the diaphragm electrode 4 is flat as shown in FIG. 30μ between
m, and the sealing pressure inside the reference pressure chamber 1 of the vacuum sensor is 6
When the pressure of the gas measured by the vacuum sensor is gradually reduced from the atmospheric pressure state while controlling the pressure to 80 Pa and applying the voltage to the fixed electrode 5 to attract the diaphragm electrode 4 to the fixed electrode 5 side by electrostatic attraction. And a case where the pressure of the gas measured by the vacuum sensor is gradually reduced from the atmospheric pressure state without performing such control.

The pressure of the gas measured by the vacuum sensor is 102
In the case of 0 Pa, the diaphragm electrode 4 has 340 Pa (1
020 Pa) acts toward the fixed electrode 5. As a result, the diaphragm electrode 4 is displaced by 30 μm toward the fixed electrode 5 as shown in FIG.

The pressure measured by the vacuum sensor is reduced,
When the pressure reaches 680 Pa, the diaphragm electrode 4
Under the pressure of 80 Pa, the displacement amount becomes 0, and FIG.
It becomes flat as shown.

When the pressure measured by the vacuum sensor drops to 340 Pa, the diaphragm electrode 4 moves 340 Pa in the direction away from the fixed electrode 5 as shown in FIG.
(= 680 Pa-340 Pa) under pressure of 30 μm
Displace. At this point, the amount of displacement of the diaphragm electrode 4 reaches the proportional limit, and a pressure lower than this cannot be measured accurately.

However, here, by applying a voltage to the fixed electrode 5, an electrostatic attraction is generated between the fixed electrode 5 and the diaphragm electrode 4, and the diaphragm electrode 4 is again moved to the state shown in FIG.
(B) It can be returned to a flat state as shown.

That is, the diaphragm electrode 4 and the fixed electrode 5
D, the area of those electrodes is S, and the fixed electrode 5
Is a voltage applied to the diaphragm electrode 4 and the fixed electrode 5, the capacitance C formed by the diaphragm electrode 4 and the fixed electrode 5 has a dielectric constant of vacuum of ε.
_When it is set to ₀ , [Expression 5] is expressed by C = ε ₀ · S / d.

Here, when a voltage V is applied to the fixed electrode 5, an electric quantity Q stored in an electric capacity C formed by the diaphragm electrode 4 and the fixed electrode 5 is expressed by the following equation (6): Q = C × V By substituting [Equation 5] into [Equation 6], [Equation 7] Q = ε ₀ · S · V / d is obtained.

That is, different quantities of electricity Q exist on the surface of the diaphragm electrode 4 and the surface of the fixed electrode 5, respectively.
The force F by which the diaphragm electrode 4 is attracted to the fixed electrode 5 is [Equation 8] F = Q / (4πε ₀ d ² ).

Here, d = 30 μm, S = 2 cm square, F =
Substituting P × S = 340 Pa × 2 cm square into [Equation 7] and [Equation 8] gives V = 1 V (volt).

That is, when the pressure measured by the vacuum sensor is 3
The diaphragm electrode 4 which has dropped to 40 Pa and has been displaced by 30 μm in a direction away from the fixed electrode 5 returns to the displacement amount of 0 by applying a voltage of 1 V (volt) to the fixed electrode 5, and the diaphragm electrode 4 The pressure can be measured until the electrode 4 is further displaced by 30 μm in the direction away from the fixed electrode 5, that is, a pressure lower by 340 Pa, and finally a pressure from 0 to 1020 Pa can be measured.

As described above, in the capacitance type vacuum sensor of the present invention, the displacement of the diaphragm electrode 4 is increased by increasing the sealing pressure inside the reference pressure chamber 1 of the vacuum sensor and simultaneously applying a voltage to the fixed electrode 5. The amount can be controlled and a wide range of pressures can be measured.

FIG. 2 shows an embodiment in which the present invention is applied to a capacitance type vacuum sensor manufactured by using a micromachine technology. Unlike ordinary machining methods, micro-machine technology is a technology for manufacturing mechanical structures by processing single-crystal silicon wafers etc. using semiconductor manufacturing process technology.Product miniaturization, mass production, manufacturing costs It is effective in reducing the amount of slag. Further, since the diaphragm electrode that repeats mechanical deformation is made of single-crystal silicon, plastic deformation is less likely to occur than that of a diaphragm electrode made of Inconel, and stable pressure measurement can be performed for a long period. Ha
tanaka, D .; Y. Sim, K .; By Minami,
"Silicon DiaphragmCapacit
ive Vacuum Sensor ”, Techni
calDigest of the 13th Se
nsor Symposium pp. 37-41 (1
995) shows an example of a report in which a capacitance type vacuum sensor is produced by using a micromachine technology.

In FIG. 2, a chamber (reference pressure chamber 1) for providing a reference pressure is provided inside the sensor, and this reference pressure chamber 1 is partitioned by a region 3 communicating with the internal space of the vacuum device 2 and a diaphragm electrode 4. A fixed electrode 5 is formed on an insulating substrate 9 so as to face the diaphragm electrode 4. In this embodiment, the diaphragm electrode 4 is made of single crystal silicon, and the insulating substrate 9 is made of Pyrex glass manufactured by Corning or SD manufactured by HOYA.
It is made of a material having a thermal expansion coefficient close to that of single crystal silicon, such as II glass.

Here, for example, the length of one side of the rectangular diaphragm electrode 4 made of single crystal silicon is 4 mm, and the thickness is 7 μm.
And the Young's modulus of silicon E = 1.7 × 10 ¹¹ Pa,
Substituting the Poisson's ratio ν = 0.006 into [Equation 2] and [Equation 3] gives [Equation 9] W ₀ = 6.7 × 10 ⁻⁸ P (m), where 60 of the 7 μm-thick diaphragm electrode % Of the diaphragm electrode is 4.2 μm.

According to [Equation 9], the pressure corresponding to W ₀ = 4.2 μm is 63 Pa, and the inside of the reference pressure chamber 1, that is, the diaphragm electrode 4 and the fixed electrode 5, as in the conventional capacitive vacuum sensor. If the space between is sealed with a pressure lower than or equal to the lower limit pressure for measurement, a pressure of 63 Pa or more cannot be measured accurately.
However, if the inside of the reference pressure chamber 1 is sealed at a pressure higher than the lower limit of measurement, for example, at a pressure of 63 Pa as in the capacitance type vacuum sensor of the present invention, a maximum of 126 Pa can be obtained.
Can be measured.

For example, the inside of the reference pressure chamber 1 is
When the gas pressure measured by the vacuum sensor is 63 Pa, the diaphragm electrode 4 is fixed to the fixed electrode 5.
When the diaphragm electrode 4 is further displaced, the pressure cannot be measured accurately.

However, as in the capacitance type vacuum sensor of the present invention, d = 7 μm and S = 16 m in [Equation 8] and [Equation 7].
By applying a value of V when m ² and F = 63 Pa × 16 mm ² are substituted, that is, a voltage of 0.46 V (volt) to the fixed electrode 5, the diaphragm electrode 4 is pulled back to the fixed electrode 5 side until it becomes flat. With such a configuration, more accurate measurement can be performed even if the pressure of the gas to be measured is lower than 63 Pa.

FIG. 3 shows an embodiment of the present invention provided with a temperature control means for maintaining a constant temperature around the diaphragm electrode 4 of the vacuum sensor.

In the present invention, the reference pressure chamber 1 inside the vacuum sensor
Inside, the volume of the gas inside the constant pressure chamber changes, and as a result, the amount of displacement of the diaphragm electrode 4 also changes, causing an error in the gas pressure measurement value measured by the vacuum sensor.

Therefore, the capacitance type vacuum sensor shown in FIG. 3 solves this problem by providing temperature control means inside the vacuum sensor.

Even in the conventional capacitance type vacuum sensor,
Due to the difference in the coefficient of thermal expansion between the diaphragm electrode and the components used around it, a change in the temperature of the vacuum sensor changes the diaphragm electrode, causing an error in the measured pressure value. Therefore, when performing highly accurate pressure measurement, a temperature control unit is provided inside the vacuum sensor.
In FIG. 3, the basic structure and measurement principle are the same as those of the embodiment shown in FIG. 1, but the temperature measurement means 1 such as a thermocouple is used.
1 is arranged around the diaphragm electrode 4 and the temperature of that portion is measured. The electric circuit 6 also serves as an electric circuit for measuring pressure from the capacitance between the diaphragm electrode 4 and the fixed electrode 5, and based on the temperature measured by the temperature measuring means 11, By confining the heat emitted by the heating means 13 such as a heater inside the vacuum sensor, the diaphragm electrode 4 functions to keep the diaphragm electrode 4 at a constant temperature with low power consumption and efficiently. This can prevent a pressure measurement error from occurring due to a temperature change of the vacuum sensor in a pressure measurement environment.

The same technique can be applied to a capacitance type vacuum sensor manufactured using the micromachine technique shown in the embodiment of FIG.

[0058]

According to the capacitive vacuum sensor of the present invention, a wide range of pressure measurement can be performed as compared with the conventional one without largely changing the structure of the conventional capacitive vacuum sensor.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a wide-band capacitance type vacuum sensor of the present invention.

FIG. 2 is a diagram illustrating an embodiment of a broadband capacitive vacuum sensor of the present invention manufactured using micromachine technology.

FIG. 3 is a diagram illustrating a broadband capacitance type vacuum sensor of the present invention having a temperature control unit.

FIG. 4 shows the gas pressure P outside the vacuum sensor and the displacement W _{O at the} center of the rectangular diaphragm electrode expressed by [Equation 4].
The graph which shows the relationship.

FIG. 5 is a diagram showing a state of displacement of a diaphragm electrode in the broadband capacitance type vacuum sensor of the present invention,
(A) is a diagram showing a state displaced away from the fixed electrode, (b) is a diagram showing a flat state,
(C) is a diagram illustrating a state in which it is displaced in a direction approaching the fixed electrode.

FIG. 6 is a diagram illustrating a conventional capacitance vacuum sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference pressure chamber 2 Vacuum apparatus 3 Area | region which communicates with the internal space of a vacuum apparatus 4 Diaphragm electrode 5 Fixed electrode 6 Electric circuit 7 Conducting wire 8 Sensor case 9 Insulating substrate 10 Getter 11 Temperature measuring means 12 Power supply line for heating means 13 Heating means 14 Insulation

Claims (3)

[Claims] 1. A pair of diaphragm electrodes and a fixed electrode facing each other at an interval are disposed inside, and a gap between the diaphragm electrode and the fixed electrode due to displacement of the diaphragm electrode according to a gas pressure to be measured. A capacitive vacuum sensor for measuring gas pressure from a change in capacitance, wherein a space between the diaphragm electrode and the fixed electrode is sealed at a pressure higher than a lower limit pressure for measurement. Capacitive vacuum sensor. 2. A displacement between the diaphragm electrode and the fixed electrode such that a displacement of the diaphragm electrode in a direction away from the fixed electrode is at most 60% of a thickness of the diaphragm electrode. 2. A wide-band capacitance type vacuum sensor according to claim 1, wherein a pressure for sealing is set. 3. The wide-band electrostatic capacitive vacuum sensor according to claim 1, wherein the amount of displacement of the diaphragm electrode in a direction away from the fixed electrode can be controlled by applying a DC voltage to the fixed electrode.