JP2002318166A - Electrostatic capacity type vacuum sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic capacity type vacuum sensor allowing the change of a measuring pressure region without changing the thickness of an elastic structure part of a diaphragm electrode and allowing the measuring pressure region of a pressure sensor to be accurately set in a relatively high pressure range without reducing the size of a fixed electrode or the diaphragm electrode. SOLUTION: The purpose is accomplished by this electrostatic capacitance type vacuum sensor wherein a projecting structure formed of an insulating material is erected on the elastic structure of the diaphragm electrode and/or the fixed electrode facing to the elastic structure so that the area of the elastic structure surrounded by plural adjacent projecting structures in the projecting structure can be set to a predetermined size.

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 vacuum sensor capable of easily changing a measurable pressure range. Further, the present invention relates to a capacitance type vacuum sensor having a measurable pressure range broadened.

[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.

A capacitance type vacuum sensor has a diaphragm electrode having an elastic structure (a movable part that causes deformation) separated by a space inside, and a fixed electrode on a rigid structure, which is arranged to face each other. When the gas pressure is applied to the electrode, the elastic structure of the diaphragm electrode is elastically deformed, and the pressure of the gas is changed by utilizing the change in the capacitance between the diaphragm electrode and the fixed electrode. It is to be measured.

FIG. 8 shows an example of a conventional capacitive vacuum sensor. A conventional capacitance vacuum sensor has a room (reference pressure chamber 1) that becomes a reference pressure inside the sensor. The reference pressure chamber 1 has a region 3 communicating with the internal space of the vacuum device 2.
And a diaphragm electrode 5 composed of an elastic structure 4 and a rigid structure 14. The fixed electrode 6 is disposed on the insulating substrate 10 having a rigid structure so as to face the diaphragm electrode 5. A getter 11 is disposed in the reference pressure chamber 1, whereby gas remaining in the reference pressure chamber 1 is adsorbed, and the pressure in the reference pressure chamber 1 is as low as or lower than the measurement lower limit pressure. Sealed with pressure.

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 5 made of an elastic diaphragm is displaced in proportion to the pressure difference. This displacement changes the capacitance between the diaphragm electrode 5 and the fixed electrode 6, and the amount of change in the capacitance between the diaphragm electrode 5 and the fixed electrode 6 is proportional to the amount of pressure change. Therefore, the electric information (the amount of change in the capacitance) through the conductor 8
Is transmitted to the electric circuit 7, and the capacitance is converted into a voltage or a current and output outside the sensor, whereby the gas pressure in the region 3 communicating with the internal space of the vacuum device 2 can be measured.

However, the amount of displacement of the elastic structure 4 of the diaphragm electrode 5 is not proportional to the pressure difference between the reference pressure chamber 1 and the region 3 communicating with the internal space of the vacuum device 2 over the entire pressure region. . In practice, the amount of displacement of the elastic structure 4 exceeds a certain value, or the elastic structure 4
Accurate pressure measurement becomes impossible at the point of contact.

When the pressure difference between the reference pressure chamber 1 and the region 3 communicating with the internal space of the vacuum device 2 is very small, the displacement of the elastic structure 4 is small, so that the electric circuit 7 uses the pressure. The difference cannot be measured, and the lower limit also has a measurement limit. For these reasons, the pressure measurement range of a general capacitive vacuum sensor is about two to three digits.

Therefore, in order to measure pressure over a wide band of three digits or more, it was necessary to use a plurality of capacitive vacuum sensors.

On the other hand, FIG. 9 shows a conventional example in which a capacitance type vacuum sensor having a diaphragm electrode 5 having two elastic structures is manufactured by a micromachine technique (K. Hatanaka, D. et al.
Y.Sim, K.Minami and M.Esashi, Technical Digest of 1
3th Sensor Symposium, pp. 37-40 (1995)). Also in this conventional example, the diaphragm electrode 5 is made up of elastic structures 12 and 13 and a rigid structure 14, and each of the elastic structures 12 and 13 has a thickness of 5 μm. The structure 13 is 4 mm square. The rigid structure 14 has a thickness of 200 μm and serves to support the elastic structures 12 and 13. The diaphragm electrode 5 is joined to the insulating substrate 10 in a vacuum. By this joining, two reference pressure chambers 1 and 1 are formed in the vacuum sensor for the respective elastic structures 12 and 13. The getters 11, 11 adsorb the gas remaining in each of the reference pressure chambers 1, 1 and always maintain the inside of the reference pressure chambers 1, 1 at a high vacuum. Further, a fixed electrode 15 is formed on the portion of the insulating substrate 10 facing the elastic structure 12 and a fixed electrode 16 is formed on the portion facing the elastic structure 13. The size of the two fixed electrodes 15 and 16 is Elastic structure 12, 1
3 corresponds to the size.

Here, if there is a pressure difference between the gas pressure externally applied to the elastic structures 12, 13 and the reference pressure chambers 1, 1, the elastic structures 12, 13 are displaced in accordance with the pressure difference, and the elastic structures 12, 13 are displaced. , 13 and the fixed electrodes 15, 16 opposed thereto, the pressure of the gas can be measured from the change in capacitance.

Since the elastic structures 12 and 13 have different sizes, their displacement amounts are different even at the same gas pressure. In fact, the larger the size of the elastic structure, the more sensitively the elastic structure is displaced to a low pressure, thus forming a vacuum sensor having a measurement sensitivity in a low gas pressure region.

That is, in the conventional capacitance type vacuum sensor shown in FIG. 9, the pressure range measured by the elastic structure 12 of 2 mm square is measured by the elastic structure 13 of 100 to 10,000 Pa and 4 mm square. The pressure range is about 1 to 100 Pa, and it is possible to measure the pressure range over four digits of 1 to 10,000 Pa in total.

Further, in the conventional capacitance type vacuum sensor based on micromachine technology, for example, the thickness of the diaphragm electrode 5 is 5 μm, and the distance between the diaphragm electrode 5 and the fixed electrodes 15 and 16 is as narrow as 4 μm. In such a case, the displacement of the elastic structures 12 and 13 is large at a high pressure such as the atmospheric pressure (100,000 Pa), and these elastic structures are pressed by the fixed electrodes 15 and 16. That is, in such a case, it is impossible to accurately measure the capacitance near the atmospheric pressure, that is, the pressure.

In this case, if the size of the elastic structures 12 and 13 is reduced, the amount of displacement of the elastic structures 12 and 13 is reduced, and pressure measurement near the atmospheric pressure is theoretically possible. However, in practice, since the sizes of the elastic structures 12 and 13 and the corresponding fixed electrodes 15 and 16 are reduced, the capacitance value itself and the capacitance change value caused by the pressure change are reduced. turn into. As a result, it becomes difficult to measure the capacitance, and it is difficult to realize a capacitance-type vacuum sensor that can measure a pressure near the atmospheric pressure without lowering the accuracy of the pressure measurement.

On the other hand, in the conventional capacitive vacuum sensor shown in FIG. 8, in order to change the measurable pressure range, the thickness of the elastic structure 4 is changed. That is, if the elastic structure 4 is made thicker, the amount of displacement of the elastic structure 4 with respect to pressure is reduced, so that the measurable pressure range can be shifted to a higher direction. However, changing the thickness of the elastic structure 4 requires a change in the manufacturing process and the thickness dimensions of the parts and the like combined with the elastic structure 4, which complicates the manufacturing process, increases the cost, and reduces the number of parts. This leads to an increase in the time and labor required for the increase and the design change.

[0016]

In a capacitive vacuum sensor, the pressure region in which the elastic structure of the diaphragm electrode is deformed in proportion to the pressure is limited, so that a wide pressure range can be measured with a single elastic structure. It is difficult to realize a capacitance-type vacuum sensor that can perform the measurement.

Generally, when designing a capacitance type vacuum sensor, the elastic structure of the diaphragm electrode is set to an appropriate thickness in accordance with the pressure range measured by the sensor. For example, in the case of realizing a capacitance type vacuum sensor that responds sensitively to low pressure, the thickness of the elastic structure of the diaphragm electrode may be made relatively thin so that the diaphragm can be easily displaced even with a slight pressure. Conversely, in order to realize a capacitance-type vacuum sensor for measuring a high pressure, the elastic structure of the diaphragm electrode may be made thicker so that the diaphragm is less likely to be displaced by pressure. However, as long as the pressure is measured by a single elastic structure, the pressure measurement range is still about two to three digits.

The measurement pressure area of the capacitance type vacuum sensor can be changed by changing the size (area) of the elastic structure of the diaphragm electrode. In other words, if the size (area) of the elastic structure is increased, the displacement of the elastic structure with respect to the pressure increases, and as a result, it is possible to manufacture a capacitive vacuum sensor having a measurement area for a relatively low pressure. it can. Conversely, if the size (area) of the elastic structure is reduced, the amount of displacement of the elastic structure with respect to pressure decreases,
As a result, a capacitance type vacuum sensor having a measurement area for a relatively high pressure can be manufactured. In particular, if the micromachine technology is used, the same structure can be easily formed over one substrate. In other words, according to this technology, it is possible to simultaneously form elastic structures of various sizes on a single substrate without increasing the number of processes, and the elastic structures having different sizes are subject to pressure in different regions. If the structure of the sensor is designed so as to perform the measurement, it is possible to measure a wider pressure range while using a single sensor.

On the other hand, when the size of the elastic structure is reduced for the purpose of measuring a high pressure region, the value of the capacitance itself is reduced, and the amount of displacement with respect to the pressure is reduced. A capacitance detection technique is required, and as a result, it is difficult to perform measurement in a pressure range of two to three digits as in the related art.

Conversely, the size (area) of the elastic structure portion is kept as it is, and the elastic structure that can be measured under a high pressure is formed inside the vacuum sensor by increasing the thickness of the elastic structure. When manufacturing a capacitive vacuum sensor having a wide pressure measurement range in combination with an elastic structure having a different thickness, elastic structures having different thicknesses are formed on the same substrate. However, this requires individual processes for forming the elastic structures having different thicknesses, and there is a problem that the advantages of the micromachine technology cannot be utilized.

Therefore, according to the present invention, the measurement pressure region can be changed without changing the thickness of the elastic structure of the diaphragm electrode, and the size (area) of the fixed electrode or the diaphragm electrode is reduced. An object of the present invention is to provide a capacitance-type vacuum sensor capable of setting a measurement pressure region of a pressure sensor to a relatively high pressure with high accuracy without having to perform the measurement.

[0022]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a capacitance type vacuum sensor proposed by the present invention is provided on a surface of a diaphragm electrode which faces an elastic electrode having an elastic structure or an elastic structure of the fixed electrode. One of the facing surfaces,
Or, on both surfaces, a projection structure made of an insulator,
The projection structure is characterized in that the projection structure is erected so that an area surrounded by an adjacent projection structure has a predetermined size.

Here, the distance between the diaphragm electrode and the fixed electrode, which are opposed to each other with a space therebetween, may be larger than the height of the protrusion structure, or may be higher than the height of the protrusion structure. Can be equal to

For example, when the distance between the diaphragm electrode and the fixed electrode which are opposed to each other with a space therebetween is equal to the height of the projection structure, that is, the vacuum sensor operates. Over the entire pressure region, the vertex side of the projection structure standing on the elastic structure in the diaphragm electrode is always in contact with the opposing fixed electrode, or the vertex side of the projection structure standing on the fixed electrode is It is assumed that each part is manufactured with its dimensions adjusted so as to always contact the opposing elastic structure.

In this case, although the elastic structure itself has a certain size (area) as a whole, even if the pressure applied to the elastic structure increases, the elastic structure in the portion where the projection structure exists has a pressure. , And only the other elastic structure portions, that is, only the minute elastic structure portions defined by the area surrounded by a plurality of adjacent protrusion structures in the protrusion structures are displaced.

The amount of displacement is substantially the same as the amount of displacement of a minute elastic structure having a size equal to the area surrounded by a plurality of adjacent protruding structures in the protruding structure. The capacitance between the fixed electrode and the fixed electrode can be considered to be equivalent to a large number of micro elastic structures arranged in parallel with the area equal to the area surrounded by a plurality of adjacent protrusion structures in the protrusion structure. it can.

Here, the protrusion structure made of an insulator is erected so that the area surrounded by a plurality of adjacent protrusion structures in the protrusion structure becomes a predetermined size. It is known in advance how much pressure and how much a minute elastic structure having a size equal to the area surrounded by a plurality of adjacent protrusion structures in the protrusion structure is deformed.

That is, since the capacitance type vacuum sensor has a large number of small elastic structures, which are grasped in advance as to how much pressure is deformed and how much, is arranged in parallel, it operates in a high pressure region. However, the capacitance formed by the entire elastic structure and the fixed electrode, and the capacitance change amount caused by the pressure change are the total of the whole, and are large values that do not hinder the measurement.

As described above, in the capacitance type vacuum sensor of the present invention, the elastic structure of the diaphragm electrode is
Small area (size) operable for high pressure area
Since a large number of micro elastic structures are arranged in parallel, it is possible to fabricate a capacitance type vacuum sensor by micromachine technology without reducing the size (area) of the elastic structure itself. To easily manufacture a capacitance-type vacuum sensor in which the area (size) of each minute elastic structure surrounded by a plurality of adjacent protrusion structures inside is set to a desired size and the measurable pressure range is changed. In addition, by reducing the area (size) of each of the minute elastic structures, the measurement pressure region of the pressure sensor can be changed as described above so that the capacitance change amount caused by the pressure change can be measured. It can be set to a high pressure range while having a value as large as possible.

Next, when the distance between the diaphragm electrode and the fixed electrode, which are opposed to each other with a space therebetween, is larger than the height of the projection structure, that is, when the pressure is sufficiently low, the displacement of the elastic structure is reduced. The size of the inside of the vacuum sensor is set and manufactured so that the amount is small and the projection structure on the elastic structure does not contact the fixed electrode, or the projection structure on the fixed electrode does not contact the elastic structure. Think about it.

In this case, the entire elastic structure is in a range below the pressure at which the protruding structure erected on the elastic structure contacts the fixed electrode or the pressure at which the protruding structure erected on the fixed electrode contacts the elastic structure. Is displaced as a single elastic structure irrespective of the arrangement interval in which the protrusion structures are erected.
Thus, it becomes possible to operate as a pressure sensor having sensitivity to low pressure.

As described above, in the range above the pressure at which the protruding structure provided on the elastic structure comes into contact with the fixed electrode, or the pressure at which the protruding structure provided on the fixed electrode comes into contact with the elastic structure, Since the capacitance-type vacuum sensor is composed of a number of small elastic structures that are preliminarily grasped at what pressure and how much deformation, they are arranged in parallel. It is possible to operate in a high pressure region while having a large value.

Therefore, the capacitance change amount caused by the pressure change is set to a large value that does not hinder the measurement, and the capacitance sensor that operates in a high pressure region while being sensitive to a low pressure is used. Type vacuum sensor can be provided.

In the above-mentioned capacitance type vacuum sensor of the present invention, the elastic structure provided in the diaphragm electrode may be constituted by a plurality of elastic structures having different sizes. For example, by making the area of each elastic structure sequentially different at a predetermined ratio so that the pressure in different pressure regions can be measured in the elastic structure portions having different areas, pressure measurement over a wide range can be performed. be able to.

Further, the elastic structure provided in the diaphragm electrode is made up of a plurality of elastic structures having different sizes, and the elastic structure of the projecting structure which stands on the surface of the elastic structure facing the fixed electrode. The area surrounded by a plurality of adjacent protrusion structures (the area is a size that is known in advance as to how much pressure is deformed and how much it is equal to the area) is made different from each other, It is possible to measure a wide pressure region, and prevent a region in which accurate pressure cannot be measured from occurring in the wide pressure region.

In the above-mentioned capacitance type vacuum sensor of the present invention, the projection structure is one of a surface of the elastic structure facing the fixed electrode, a surface of the fixed electrode facing the elastic structure, or A structure in which a plurality of protrusion structures are independently erected on both surfaces, or a structure in which a plurality of protrusions are erected so as to intersect with each other can be adopted.

[0037]

FIG. 1 shows a preferred embodiment of the present invention.
This will be described with reference to FIGS.

The capacitance type vacuum sensor of the present invention shown in FIG. 1 is manufactured by applying, for example, a semiconductor manufacturing process technology, and includes a pressure detecting section (mainly an insulating substrate 10 in the figure).
And the rigid structure 14) have a size of several mm to
The thickness is about several tens mm and the thickness is about 1.5 mm.

This capacitance type vacuum sensor is a vacuum device 2
The gauge port and the flange port 9 are attached, and are used for measuring the pressure inside the vacuum apparatus 2.

The diaphragm electrode 5 of the capacitance type vacuum sensor has an elastic structure 4, and is composed of the elastic structure 4 and the rigid structure 14. The reference pressure chamber 1 is sealed at a high vacuum pressure in a region sandwiched between the diaphragm electrode 5 and the rigid structure insulating substrate 10 on which the fixed electrode 6 is formed. The getter 11 functions to adsorb the gas remaining in the reference pressure chamber 1 and always keep the internal pressure at a high vacuum.

The capacitance-type vacuum sensor shown in FIG. 1 has a diaphragm electrode 5 which is disposed facing the inside with a space therebetween.
The distance between the fixed electrode 6 and the fixed electrode 6 is set to be equal to the height of the protrusion structure 17 made of an insulator standing upright on the elastic structure 4. The height of the fixed electrode 6 is adjusted so as to always be in contact with the opposed fixed electrode 6.

As shown in FIG. 2A, the projection structure 17 includes a plurality of projection structures 17a, 17b, 17c, and 17d.
Etc. are independently erected, or
As shown in FIG. 2B, a plurality of protrusion structures 17e, 17f, 17g, 17h, etc. in the form of protrusions may be provided so as to intersect each other.

FIG. 2A shows a plurality of projection structures 17a, 1
7b, 17c, 17d, etc., are shown as examples in which one by one is independently erected on the elastic structure 4 of the diaphragm electrode 5, and a projection structure such as a quadrangular pyramid or a cone (in the illustrated case, (Projection structures) are individually erected in the form of islands. The area surrounded by a plurality of adjacent protrusion structures 17a, 17b, 17c, and 17d in the protrusion structure 17 has a predetermined size (area),
That is, the elastic structure 4a having a small area has a size (area) which is grasped in advance as to how much pressure and how much the elastic structure 4a is deformed.

FIG. 2 (b) shows a plurality of protrusions 17e, 17f, 17g, 17h, etc., which are in the form of a ridge, which are erected so as to intersect with each other. Thus, a lattice-like projection structure is formed.
Also in this case, the area surrounded by a plurality of adjacent projection structures 17e, 17f, 17g, and 17h in the projection structure 17 has a predetermined size (area), that is,
The elastic structure 14a having a small area has a size (area) which is grasped in advance as to how much pressure and how much the elastic structure 14a is deformed.

In FIG. 1, when the pressure in a region 3 communicating with the internal space of the vacuum device 2 (the pressure in this region is substantially equal to the internal pressure of the vacuum device 2) changes, a part of the diaphragm electrode 5 responds accordingly. The force that presses a certain elastic structure 4 also changes, and the distance between the elastic structure 4 and the fixed electrode 6 arranged opposite to it changes according to the pressure.

As a result, the capacitance between the diaphragm electrode 5 and the fixed electrode 6 also changes. Therefore, the capacitance between the two electrodes is detected by the electric circuit 7 through the conducting wire 8 and converted into a voltage or a current and output to the outside of the vacuum sensor to thereby output the region 3 communicating with the internal space of the vacuum device 2.
Can be measured.

Here, the state of displacement of the elastic structure 4 with respect to the pressure and the capacitance between the diaphragm electrode 5 and the fixed electrode 6 will be described with reference to FIGS. 3 (a) to 3 (d) and FIG. . FIGS. 3A to 3D show how the elastic structure 4 is displaced by the pressure in the region 3 communicating with the internal space of the vacuum device 2 in the embodiment of the present invention shown in FIG. It is a diagram, and portions unnecessary for description are omitted. FIG.
FIG. 4 is a diagram showing a characteristic in which the capacitance between the diaphragm electrode 5 and the fixed electrode 6 changes with pressure.

When the pressure applied to the elastic structure 4 is low, the amount of displacement of the elastic structure 4 is small, and the elastic structure 4 is almost flat (FIG. 3A). Diaphragm electrode 5 at this time
The capacitance between the electrode and the fixed electrode 6 is set as the origin of the pressure-capacitance characteristics (point a in FIG. 4).

Here, when pressure is applied to the elastic structure 4 from the outside, the elastic structure 4 tends to be displaced accordingly. However, since the projection structure 17 becomes a column, the elastic structure 4
7, a minute elastic structure 4 having a size equal to the area surrounded by the adjacent protrusion structures 17a, 17b, 17c, 17d, etc. in the protrusion structure.
a, 4b, 4c, etc. (FIG. 3 (b)).

At this time, the capacitance between the diaphragm electrode 5 and the fixed electrode 6 is an elastic structure having a size equal to the arrangement interval of the protrusion structures 17, that is, the adjacent protrusion structures 17 a in the protrusion structures 17. Between the small elastic structures 4a, 4b, 4c, etc., having a size equal to the area surrounded by 17b, 17c, 17d, etc., and the fixed electrodes 6 facing the respective minute elastic structures 4a, 4b, 4c, etc. The capacitance is equivalent to a state in which many are arranged in parallel. Then, the total sum of the capacitances between the minute elastic structures 4a, 4b, 4c and the like and the fixed electrode 6 facing them is detected as the capacitance between the diaphragm electrode 5 and the fixed electrode 6. Therefore, the capacitance change amount with respect to the pressure is detected as a large value (point b in FIG. 4).

When the pressure further increases, the displacement amount of the elastic structure 4 further increases (FIG. 3C), and the capacitance change amount also increases (point c in FIG. 4). However, when the pressure exceeds a certain value, the displacement of the elastic structure 4 also increases (see FIG. 3).
(D)), the pressure-capacitance characteristics lose linearity (point d in FIG. 4). Usually, when used as a vacuum sensor, an area in the range of a to c in FIG. 4 is used.

Incidentally, the maximum measurement pressure limit corresponding to the point c in FIG. 4 depends on the arrangement interval of the projection structures 17. For example, when the elastic structure 4 is a single-crystal silicon having a thickness of 7 μm,
The elastic structure 4a has a square shape, and the arrangement interval of the protrusion structures 17 (the distance between the protrusion structures 17a and 17b in FIG.
The distance between the projection structures 17a and 17c) is 0.6 m, respectively.
m, the maximum measured pressure limit is the atmospheric pressure (100,00
0 Pa) and 3 mm each, the maximum measurement pressure limit is about 300 Pa.

In the conventional capacitive vacuum sensor shown in FIG. 8, when the measurement pressure range is changed, the thickness is changed by changing the thickness of the elastic structure 4. However, the two elastic structures shown in FIG. In the conventional capacitance type vacuum sensor having the same, since the elastic structures 12 and 13 are formed simultaneously in the manufacturing process, it is impossible to change the measurement pressure region by making the thicknesses thereof different from each other. Therefore, the elastic structure 12,
The measurement pressure range is controlled by changing the size of 13. However, on the other hand, in order to detect a high pressure region, the size of the elastic structure is reduced,
In that case, the capacitance itself becomes small and the amount of change in the capacitance due to the pressure change also decreases, making accurate pressure measurement difficult.

On the other hand, in the embodiment of the present invention shown in FIG.
By changing the arrangement interval of the protrusion structures 17, that is, adjacent protrusion structures 17a, 17
The measurement pressure region of the vacuum sensor can be changed by changing the area of the minute elastic structures 4a, 4b, 4c and the like surrounded by b, 17c, 17d and the like.

That is, even if the size (area) of the entire elastic structure 4 is not reduced, the arrangement interval of the protrusion structures 17 can be reduced.
Adjacent protrusion structures 17a, 17b among the protrusion structures 17;
Fine elastic structure 4a surrounded by 17c, 17d, etc.
By reducing the area such as the above, the measurement pressure area of the vacuum sensor can be changed to a relatively high pressure area. And
Even in this case, considering the elastic structure 4 as a whole, it is a structure in which many minute elastic structures 4a and the like are arranged in parallel.
The amount of change in capacity caused by the change in pressure can be kept to a level that does not hinder measurement.

On the contrary, conversely, even if the entire elastic structure 4 is enlarged, as long as the arrangement interval of the protrusion structures 17 is maintained, that is, the adjacent protrusion structures 17a in the protrusion structures 17,
Measurement is possible if the protrusion structures 17 (17a, 17b, 17c, 17d, etc.) are erected so that the area of the minute elastic structures 4a, 4b, 4c, etc. surrounded by 17b, 17c, 17d, etc. is maintained. The capacitance and the amount of change in capacitance due to pressure change can be further increased without changing the pressure range, and a capacitance-type vacuum sensor capable of measuring pressure with higher accuracy can be realized.

As described above, without changing the size (area) of the elastic structure 4, the arrangement interval of the projection structures 17 is changed, or the arrangement interval of the projection structures 17 is maintained.
Enlarging the entire elastic structure 4 can be easily performed when a capacitance type vacuum sensor is manufactured by a micromachine technology. Therefore, it is possible to easily manufacture a capacitance type vacuum sensor having different measurable pressure regions.

FIG. 5 shows another embodiment of the present invention. 5, elements substantially the same as the elements described in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The capacitance-type vacuum sensor shown in FIG. 5 has a diaphragm electrode
1 is different from that of the embodiment shown in FIG. 1 in that the distance between the electrode and the fixed electrode 6 is larger than the height of the projecting structure 17 made of an insulator standing upright on the elastic structures 24 and 34. ing.

Therefore, in the capacitive vacuum sensor shown in FIG. 5, the pressure in the region 3 communicating with the internal space of the vacuum device 2 is sufficiently low, and the elastic structures 24 and 34 of the diaphragm electrode 5 are substantially flat without displacement. In one state, the projection structure 17 is not in contact with the fixed electrode 6.

Further, the capacitance type vacuum sensor shown in FIG. 5 is different from FIG. 1 in that the elastic structure provided in the diaphragm electrode 5 comprises a plurality of elastic structures 24 and 34 having different sizes. This is different from the embodiment. In FIG. 5, the size (area) of the right elastic structure 24 supported by the rigid structures 14 is the rigid structure 1.
It is smaller than the size (area) of the left elastic structure 34 supported by 4 and 14.

FIGS. 6 (a) to 6 (d) are views showing a state in which one elastic structure 24 of the embodiment shown in FIG. 5 is displaced by pressure, and FIG. FIG. 9 is a characteristic diagram showing a state of a change in capacitance between the diaphragm electrode 5 and the fixed electrode 6 at the time.

First, when the pressure in the region 3 communicating with the internal space of the vacuum device 2 is very small, the amount of displacement of the elastic structure 24 is very small, and the elastic structure 24 is almost flat (FIG. 6). (A)). Then, the capacitance between the diaphragm electrode 5 and the fixed electrode 6 at this time is set as the origin of the pressure-capacitance characteristic (point a in FIG. 7A).

Next, when the pressure gradually increases, the elastic structure 24
Are displaced (FIG. 6B), and the capacitance increases in proportion to the pressure (the area indicated by b in FIG. 7A). When the pressure further increases, the tip of the projection structure 17 starts to contact the fixed electrode 6, whereby the amount of change in capacitance starts to decrease, and this state means that almost all of the projection structure 17 formed on the elastic structure 24 is fixed. 6 (Fig. 6 (c))
During this time, the pressure-capacitance characteristics lose linearity (the area indicated by c in FIG. 7A).

However, when the pressure is further increased thereafter, as shown in the embodiment of FIGS.
Since the capacitance changes while acting in the same manner as connecting a large number of small capacitance sensors having the same size as the arrangement interval in parallel, the pressure-capacitance characteristics eventually show linearity again ( An area indicated by d in FIG. 7A) can accurately measure pressure from this part.

However, in this method, a range in which an accurate pressure cannot be measured temporarily occurs, such as a region indicated by c in FIG. 7A.

Therefore, as shown in FIG. 5, a plurality of elastic structures 2 having different sizes are accommodated in one capacitive vacuum sensor.
4 and 34 are provided. In addition, each elastic structure 2
Protrusions 17 and 17 having different arrangement intervals are provided on the upper and lower sides 4 and 34 (in the embodiment shown in FIG. 5, the arrangement intervals of the projection structures standing on the elastic structure 34 on the left side in FIG. Is larger than the arrangement interval of the protrusion structures standing on the elastic structure 24 on the right side in the figure).

For example, here, the elastic structure 34 in FIG.
The dimensions of A and B indicating the size of 24, the dimensions of C and D indicating the arrangement interval of the projection structure are A = 5 mm, B = 4 m
m, C = 2.5 mm, D = 0.6 mm, elastic structure 3
In any of 4 and 24, assuming that the surface surrounded by the adjacent protruding structures is a square, pressure-capacitance characteristics can be obtained from the respective elastic structures as shown in FIG. 7B.

These are the sizes and protrusions of the elastic structures 24 and 34.
Since the arrangement intervals of the raised structures 17 are different, in FIG.
Area where accurate pressure cannot be measured as shown in c.
The pressure at which the zone appears differs. That is, at A in FIG.
Is 10^-2-10^-110 for Pa and B^-1-10¹P
a, 10 for C¹-10³10 for Pa and D³-10 ⁵
It is possible to accurately measure the pressure range of Pa
10 in the body^-2-10⁵Measurement of pressure over a wide range of Pa
It becomes possible.

That is, as shown in FIG. 5, the area surrounded by a plurality of adjacent protrusion structures among the protrusion structures erected on the elastic structures 24 and 34 having different areas is as follows.
The area surrounded by a plurality of adjacent protrusion structures among the protrusion structures erected on the elastic structure 24 and the plurality of adjacent protrusion structures among the protrusion structures erected on the elastic structure 34 By making them different from each other by the area surrounded by, it is possible to measure a wide pressure region, and furthermore, in such a wide pressure region, there is no region where accurate pressure cannot be measured. Can be

As described above, according to the capacitance type vacuum sensor shown in FIG. 5, the distance between the diaphragm electrode 5 and the fixed electrode 6 which are opposed to each other with a space therebetween is set to an elastic structure. By setting the height to be greater than the height of the projection structure made of an insulator, the pressure to be measured is very small, and the top of the projection structure standing on the elastic structure faces the fixed electrode. The pressure measurement at the time when it is not in contact with can be performed. Further, after the pressure is increased and the apex side of the protrusion structure erected on the elastic structure comes into contact with the opposing fixed electrode, as described with reference to FIGS. As a pressure sensor in which a large number of elastic structures having a small area to be surrounded are installed in parallel, pressure measurement can be performed up to a relatively high pressure region. Thus, a measurable pressure region can be expanded from a low pressure region to a relatively high pressure region.

Further, as in the capacitance type vacuum sensor shown in FIG. 5, the elastic structure of the diaphragm electrode 5 is made up of a plurality of elastic structures 24 and 34 having different sizes. In order to measure the pressures in the different pressure regions in the elastic structure portions having different areas, the respective elastic structures 24 and 34 are accurately formed by sequentially arranging the areas of the respective elastic structures at predetermined ratios to have different sizes. The pressure range that can be measured can be sequentially changed to enable pressure measurement over a wide range.
This is because when the distance between the diaphragm electrode and the fixed electrode, which are opposed to each other with a space therebetween, is equal to the height of the protrusion structure (the embodiment shown in FIG. 1), or is larger than the height of the protrusion structure (FIG. 1). 5 embodiment).

Further, the elastic structures of the diaphragm electrode 5 are different from each other in size.
34 and an area surrounded by a plurality of adjacent protrusion structures among the protrusion structures standing on the surface of the elastic structure facing the fixed electrode (this area is The degree of deformation is a magnitude that has been grasped in advance and the area is an area), so that a wide pressure region can be measured. An area where the pressure cannot be measured can be prevented.

Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to such embodiments, and various modifications may be made within the technical scope understood from the appended claims. It can be changed to the form.

For example, FIGS. 1, 2 (a), (b), and FIG.
In the first embodiment, the projection structure made of an insulator is provided upright on the surface of the diaphragm electrode 5 facing the fixed electrode 6 of the elastic structure 4, 24, 34. Alternatively, a structure in which a protrusion structure made of an insulator is provided upright on a surface of the fixed electrode 6 facing the elastic structures 4, 24, 34 may be employed. Further, it is sufficient if the area surrounded by a plurality of adjacent protrusion structures in the protrusion structures is large enough to grasp in advance how much pressure and how much deformation will occur.
Projection structures made of an insulator are provided on both the surface of the fixed electrode 6 facing the fixed electrode 6 and the surface of the fixed electrode 6 facing the elastic structure 4, 24, 34. The structure can also be used. Either structure can be easily manufactured using micromachine technology.

[0076]

According to the present invention, the arrangement of the projection structure formed on the elastic structure of the diaphragm electrode and / or on the fixed electrode without changing the size of the fixed electrode or the diaphragm electrode of the capacitance type vacuum sensor. The measurement pressure range of the vacuum sensor can be changed only by changing the interval.

Further, by reducing the area (size) surrounded by the protrusion structure adjacent to the protrusion structure formed on the elastic structure and / or the fixed electrode, the measurement pressure area of the pressure sensor can be relatively high. In the case of setting as well, it is not necessary to reduce the size of the fixed electrode and the diaphragm electrode as a whole, so that the value of the capacitance formed by these electrodes and the amount of change in the capacitance that changes due to pressure are also reduced. Not even. Thus, pressure measurement can be performed in a relatively high pressure range and with high accuracy.

On the other hand, even when the measurement pressure range of the pressure sensor is changed, it is not necessary to change the thickness of the elastic structure portion, so that the design change is performed in consideration of the thickness dimensions and tolerances of each portion inside the vacuum sensor. It is not necessary to do this, but rather, it is possible to manufacture capacitance-type vacuum sensors corresponding to various measurement pressure regions simply by changing the arrangement interval of the projection structure. As a result, there are effects such as simplification of the manufacturing process, reduction of the manufacturing cost, reduction of the number of parts, and reduction of time and labor for design change.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a preferred embodiment of the present invention.

FIGS. 2A and 2B are diagrams for explaining a projection structure adopted in the capacitance type vacuum sensor of the present invention shown in FIG. 1; FIG.
Is a perspective view illustrating a plurality of projection structures each independently standing on the elastic structure, and (b) is a plurality of projection structures standing on the elastic structure such that a plurality of protrusions intersect. FIG.

3A and 3B are diagrams showing a state of displacement of an elastic structure of the capacitive vacuum sensor of the present invention shown in FIG. 1, wherein FIG. 3A shows a case where pressure applied to the elastic structure is low, and FIG. (C) shows a case where displacement starts to occur for each minute elastic structure due to external pressure applied to the elastic structure, and (d) shows a case where the amount of displacement of the elastic structure increases due to an increase in the pressure applied to the elastic structure from the outside. This is the case where the amount of displacement of the elastic structure further increases due to the application of pressure.

FIG. 4 is a diagram showing pressure-capacitance characteristics in the capacitance-type vacuum sensor of the present invention shown in FIG. 1;

FIG. 5 is a diagram showing another preferred embodiment of the present invention.

6A and 6B are views showing the state of displacement of an elastic structure of the capacitance type vacuum sensor of the present invention shown in FIG. 5, wherein FIG. 6A shows a case where the pressure applied to the elastic structure is low, and FIG. If the elastic structure begins to be displaced by external pressure,
(C) shows a state in which the pressure applied to the elastic structure from the outside increases, and almost all of the protrusion structures on the elastic structure are in contact with the fixed electrode;
(D) is a case where a stronger pressure is applied to increase the displacement amount for each minute elastic structure.

7A is a characteristic diagram showing a state of a change in capacitance between a diaphragm electrode and a fixed electrode regarding one elastic structure of the capacitance type vacuum sensor of the present invention shown in FIG. 5; FIG. 6B is a diagram showing pressure versus capacitance characteristics in the capacitance type vacuum sensor of the present invention shown in FIG.

FIG. 8 is a diagram showing a conventional capacitance vacuum sensor.

FIG. 9 is a diagram showing another conventional capacitance vacuum sensor.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 reference pressure chamber 2 vacuum device 3 region communicating with the internal space of vacuum device 4 elastic structure 5 diaphragm electrode 6 fixed electrode 7 electric circuit 8 conductive wire 9 sensor case 10 insulating substrate 11 getter 12 elastic structure having a size of 2 mm square 13 size 4 mm square elastic structure 14 Rigid structure 15 Fixed electrode 16 Fixed electrode 17 Projection structure 17a, 17b, 17c, 17d Independent projection structure 17e, 17f, 17g, 17h Projection structure where projections intersect

Claims (6)

[Claims] A diaphragm electrode having an elastic structure and a fixed electrode on a rigid structure are arranged to face each other with a space therebetween, and when a gas pressure is applied to the diaphragm electrode from the outside, the diaphragm electrode is connected to the fixed electrode. The capacitance type vacuum sensor of the principle of measuring the pressure of the gas by utilizing the change in the capacitance between the diaphragm electrode and the fixed electrode due to the elastic deformation of the elastic structure, A projection structure made of an insulator is provided on one or both surfaces of the surface facing the fixed electrode of the elastic structure, or the surface facing the elastic structure of the fixed electrode, in the projection structure. An electrostatic capacitance type vacuum sensor, wherein an area surrounded by an adjacent protrusion structure is provided upright so as to have a predetermined size. 2. The electrostatic capacitance type according to claim 1, wherein the distance between the diaphragm electrode and the fixed electrode, which are opposed to each other with a space therebetween, is equal to the height of the projection structure. Vacuum sensor. 3. A capacitance type vacuum as set forth in claim 1, wherein a distance between a diaphragm electrode and a fixed electrode which are disposed to face each other with a space therebetween is larger than a height of said projection structure. Sensor. 4. The electrostatic capacitance type according to claim 1, wherein the diaphragm electrode includes a plurality of elastic structures having different sizes. Vacuum sensor. 5. The projection structure according to claim 1, wherein the projection structure includes a plurality of projection structures on one or both of a surface of the elastic structure facing the fixed electrode and a surface of the fixed electrode facing the elastic structure. The capacitance type vacuum sensor according to any one of claims 1 to 4, wherein each of them is independently erected. 6. The projection structure has a plurality of ridges on one or both of a surface of the fixed electrode facing the fixed electrode and a surface of the fixed electrode facing the elastic structure. The capacitance type vacuum sensor according to any one of claims 1 to 4, wherein the capacitance type vacuum sensor is set up so as to intersect.