Vacuum measurement system

Abstract

To stabilize measurement accuracy by a single sensor, and enable measurement of a more wide pressure range.SOLUTION: A measurement circuit 104 is configured to obtain a pressure value a diaphragm 102 receives on the basis of displacement of the diaphragm 102. A correction circuit 105 is configured to, in a range larger than a reference value having the pressure value the measurement circuit 104 obtains set, correct the pressure value on the basis of a condition set different from a range smaller than the reference value, in which the set condition may be, for example, a function (conversion expression) that obtains a correction value from the pressure value, and the reference value may be, for example, the pressure value the measurement circuit 104 obtains at a point of time when the diaphragm 102 (movable electrode 107) starts contacting with a stationary part 101(stationary electrode 106).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vacuum measurement system. [Background technology]

[0002] There is a pressure sensor that includes a first diaphragm portion in the center, a central thick portion that surrounds the first diaphragm portion, and a second diaphragm portion around the central thick portion (Patent Document 1). This pressure sensor measures a first pressure range by the displacement of the second diaphragm portion, and after the central thick portion abuts against the base, measures a second pressure range by the displacement of the first diaphragm portion. By providing a single sensor with portions that measure multiple pressure ranges in this way, it is possible to measure a wider pressure range with a single sensor, and the effect of compactness can be obtained. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-178533 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the current demand for more advanced control technology for semiconductor manufacturing equipment, there is a demand for pressure sensors to be improved in terms of stabilizing measurement accuracy in addition to being more compact.

[0005] The present invention has been made to solve the above problems, and has an object to stabilize the measurement accuracy with one sensor and enable measurement over a wider pressure range. [Means for solving the problem]

[0006] The vacuum measurement system of the present invention comprises a fixed portion having a flat surface, a diaphragm having a flat opposing surface spaced apart from the fixed portion and facing the flat surface, a convex structure formed on at least one of the flat surface and the opposing surface for preventing contact and adhesion between the flat surface and the opposing surface, a measurement circuit configured to determine a pressure value received by the diaphragm based on the displacement of the diaphragm, and a correction circuit that corrects the pressure value under set conditions when the pressure value determined by the measurement circuit is in a range greater than a set reference value.

[0007] In one configuration example of the above vacuum measurement system, the correction circuit corrects the pressure value under the set additional condition when the pressure value determined by the measurement circuit is in a range larger than an additional reference value that is larger than the reference value.

[0008] In one configuration example of the above vacuum measurement system, a fixed electrode is formed on the flat surface of the fixed part, and a movable electrode is provided on the opposing surface of the diaphragm and faces the fixed electrode, the structure prevents contact and adhesion between the fixed electrode and the movable electrode, and the measurement circuit converts the capacitance value between the movable electrode and the fixed electrode into a pressure value and outputs it.

[0009] In one configuration example of the above vacuum measurement system, the measurement circuit converts the voltage value applied to the movable electrode and the fixed electrode into a pressure value in a range larger than a reference value and outputs the pressure value. Effect of the Invention

[0010] As described above, according to the present invention, when the pressure value determined by the measurement circuit is in a range greater than a set reference value, the pressure value is corrected according to set conditions, thereby stabilizing the measurement accuracy and enabling a wider pressure range to be measured with a single sensor. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a configuration diagram showing the configuration of a vacuum measurement system according to an embodiment of the present invention. [Figure 2A]FIG. 2A is an explanatory diagram for explaining each mode in the vacuum measurement system according to the embodiment of the present invention. [Figure 2B] FIG. 2B is an explanatory diagram for explaining each mode in the vacuum measurement system according to the embodiment of the present invention. [Figure 2C] FIG. 2C is an explanatory diagram for explaining each mode in the vacuum measurement system according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a characteristic diagram showing a change in capacitance with respect to pressure applied to the diaphragm 102. As shown in FIG. [Figure 4] FIG. 4 is a characteristic diagram showing a change in capacitance with respect to the pressure applied to the diaphragm 102. As shown in FIG. [Diagram 5] FIG. 5 is a configuration diagram showing the configuration of another vacuum measurement system according to an embodiment of the present invention. [Figure 6] FIG. 6 is a configuration diagram showing the configuration of another vacuum measurement system according to an embodiment of the present invention. [Figure 7] FIG. 7 is a configuration diagram showing the configuration of another vacuum measurement system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A vacuum measurement system according to an embodiment of the present invention will now be described with reference to Fig. 1. This vacuum measurement system includes a fixed portion 101, a diaphragm 102, a structure 103, a measurement circuit 104, and a correction circuit 105.

[0013] The fixed portion 101 has a flat surface 121, and the diaphragm 102 has a flat opposing surface 122 that faces the flat surface 121. The diaphragm 102 is formed on the fixed portion 101 at a distance and is made displaceable.

[0014] The diaphragm 102 is supported on the fixed part 101 by a support part 112 provided on the diaphragm substrate 111. The support part can be provided on the fixed part 101. For example, the fixed part 101 and the diaphragm substrate 111 are square in plan view. The fixed part 101 and the diaphragm substrate 111 can be in a shape other than a square in plan view. The inner area of ​​the support part 112 of the diaphragm 102 can be circular in plan view. The fixed part 101 and the diaphragm substrate 111 (the diaphragm 102) can be made of an insulator such as sapphire or alumina ceramic. A reference chamber 115 is formed between the fixed part 101 and the diaphragm 102. The reference chamber 115 is, for example, a vacuum.

[0015] The structure 103 is composed of convex portions provided at multiple locations on the opposing surface 122. The structure 103 is provided to prevent contact and adhesion between the flat surface 121 and the opposing surface 122. The structure 103 can be composed of micro-pillars provided at multiple locations. By providing the structure 103 made of multiple micro-pillars, the area where the diaphragm 102, which is subjected to a large pressure, contacts the fixed part 101 can be reduced to the location of the structure 103. The structure can also be provided on the flat surface 121. The structure 103 can be composed of convex portions formed by processing the opposing surface 122 of the diaphragm 102.

[0016] The measuring circuit 104 determines the pressure value received by the diaphragm 102 based on the displacement of the diaphragm 102. In this example, the measuring circuit 104 converts the capacitance value between the movable electrode 107 and the fixed electrode 106 into a pressure value and outputs it. A change in the capacitance value between the movable electrode 107 and the fixed electrode 106 due to the displacement of the diaphragm 102 is obtained as a change in the pressure received by the diaphragm 102. The fixed electrode 106 is formed on a flat surface 121 of the fixed portion 101, and the movable electrode 107 is provided on an opposing surface 122 of the diaphragm 102 so as to face the fixed electrode 106.

[0017] When the structure 103 is composed of convex portions formed by processing the opposing surface 122 of the diaphragm 102, the movable electrode 107 can be formed on the opposing surface 122 in the gaps between the multiple convex portions (micro-pillars) that constitute the structure 103. The structure 103 prevents the fixed electrode 106 and the movable electrode 107 from contacting each other.

[0018] When the pressure value found by the measurement circuit 104 is in a range greater than a set reference value, the correction circuit 105 corrects the pressure value under a condition set different from the range smaller than the reference value. The set condition can be, for example, a function (conversion formula) for finding the correction value from the pressure value. The reference value can be, for example, the pressure value found by the measurement circuit 104 at the time when the diaphragm 102 (movable electrode 107) starts to contact the fixed part 101 (fixed electrode 106).

[0019] The vacuum measurement system of the embodiment expands the range of measurement pressure by using a first mode in which measurement is performed with the diaphragm 102 (movable electrode 107) not in contact with the fixed portion 101 (fixed electrode 106) as shown in Figures 2A and 2B, and a second mode in which measurement is performed with the diaphragm 102 (movable electrode 107) in contact with the fixed portion 101 (fixed electrode 106) as shown in Figure 2C.

[0020] In the first mode, the measurement circuit 104 outputs the displacement state of the diaphragm 102 as a pressure value. In the second mode, after the diaphragm 102 bends and comes into contact with the fixed part 101, the measurement circuit 104 outputs the state of the contact area as a pressure value, and the correction circuit 105 corrects it.

[0021] For example, in both the first and second modes, the measurement circuit 104 converts the capacitance between the fixed electrode 106 and the movable electrode 107 into a pressure value and outputs it. For example, the change in capacitance with respect to the pressure received by the diaphragm 102 differs between the first region and the second region at the boundary of pressure p1, as shown in Fig. 3. When the diaphragm 102 (movable electrode 107) starts to contact the fixed portion 101 (fixed electrode 106), the change in the capacitance value with respect to the change in pressure becomes larger.

[0022] In this way, in the second mode, since the change in capacitance value in response to a change in pressure differs from that in the first mode, the pressure value obtained by the measurement circuit 104 is corrected by the correction circuit 105. The reference value by the correction circuit 105 can be determined by obtaining the change in capacitance value between the fixed electrode 106 and the movable electrode 107 measured by the measurement circuit 104 through an experiment or the like, as shown in Fig. 3, and can be set as the pressure value of pressure p1 at which the rate of increase in capacitance value in response to an increase in pressure is changing.

[0023] In the second mode, which is a certain range from when the diaphragm 102 (movable electrode 107) starts to contact the fixed portion 101 (fixed electrode 106), the rate of increase in capacitance value relative to an increase in pressure is greater than in the first mode. However, when the contact area becomes large to a certain extent, the rate of increase in capacitance value relative to an increase in pressure becomes smaller, as shown in the region of the third mode in FIG.

[0024] In the second mode, the non-contact area of ​​the diaphragm 102 bends with the edge of the contact area of ​​the diaphragm 102 as a fulcrum. When the non-contact area, which has become smaller, approaches its displacement limit due to an increase in pressure received by the diaphragm 102, the amount of displacement of the non-contact area relative to the increase in pressure decreases, and the rate of increase in the contact area decreases. Therefore, as shown in Figure 4, when the pressure further increases after the second mode and exceeds a certain pressure value p2, the third mode is entered, and the application of pressure continues, and the rate of increase in the capacitance value relative to the increase in pressure decreases.

[0025] That is, for the first mode, the following formula (1) holds. C is the capacitance value, ε is the dielectric constant in a vacuum, S is the effective electrode area, and d is the average electrode spacing. P1, P2, and P3 are the applied pressures in the respective modes. For the second mode, the following formula (2) holds. Similarly, for the third mode, the following formula (3) holds.

[0026]

number

[0027] In this way, in the third mode, the change in capacitance value in response to a change in pressure is different from that in the second mode, so that the pressure value found by the measurement circuit 104 can be further corrected by the correction circuit 105, making it possible to measure a higher pressure range. In this case, the correction circuit 105 corrects the pressure value using the set additional condition when the pressure value found by the measurement circuit 104 is in a range larger than an additional reference value that is larger than the reference value. The set additional condition can be, for example, a function (conversion formula) that finds a correction value from the pressure value.

[0028] In addition, in a range larger than the reference value (second mode, third mode), the measurement circuit 104 can also convert the voltage value applied to the movable electrode 107 and the fixed electrode 106 into a pressure value and output it. For example, in the second mode and the third mode, the diaphragm 102 in the area between the convex parts provided at multiple locations constituting the structure 103 is bent, and the movable electrode 107 comes into contact with the fixed electrode 106, causing a short circuit between the electrodes. In this state, the contact position is identified by reading it as the voltage value applied to the fixed electrode 106 and the movable electrode 107, and it is possible to convert (convert) it into an area to a pressure value. If the pressure on the diaphragm 102 is isotropic, the diaphragm 102 with a uniform thickness deforms from the center and starts contact, and it is known in advance that the contact area spreads outward as the pressure increases. Therefore, there is no need to grasp the resistance value coordinates of the contact area in a planar manner as in an electrostatic touch panel, and measurement can be simplified.

[0029] 5, a dielectric layer 108 can be formed so as to cover the surface of the movable electrode 107. By providing the dielectric layer 108, the dielectric constant between the fixed electrode 106 and the movable electrode 107 can be increased, and the sensitivity of the capacitance measurement can be improved.

[0030] 6, a structure 103a composed of convex portions formed at multiple locations can be disposed on the movable electrode 107. In this case, the movable electrode 107 can be formed over almost the entire area of ​​the opposing surface 122. With this configuration, the material constituting the structure 103a can be appropriately set, and the structure 103a can be formed of a material having a higher dielectric constant than the material constituting the diaphragm 102. In this way, the dielectric constant between the fixed electrode 106 and the movable electrode 107 can be increased, and the sensitivity of the capacitance measurement can be improved.

[0031] Furthermore, as shown in FIG. 7, a structure 103a composed of convex portions formed in multiple locations can be arranged on the movable electrode 107 (opposing surface 122), and a structure 103b composed of convex portions formed in multiple locations can be arranged on the fixed electrode 106 (flat surface 121).

[0032] As described above, according to the present invention, when the pressure value determined by the measurement circuit is in a range greater than a set reference value, the pressure value is corrected according to set conditions, thereby stabilizing the measurement accuracy and enabling a wider pressure range to be measured with a single sensor.

[0033] It should be noted that the present invention is not limited to the above-described embodiments, and it is apparent that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0034] 101... Fixed part, 102... Diaphragm, 103... Structure, 104... Measurement circuit, 105... Correction circuit, 106... Fixed electrode, 107... Movable electrode, 111... Diaphragm substrate, 112... Support part, 115... Reference chamber, 121... Flat surface, 122... Opposing surface.

Claims

1. A fixing portion having a flat surface; a diaphragm having a flat opposing surface spaced apart from the fixed portion and facing the flat surface; a convex structure formed on at least one of the flat surface and the opposing surface for preventing contact and adhesion between the flat surface and the opposing surface; A measurement circuit configured to determine a pressure value received by the diaphragm based on the displacement of the diaphragm; a correction circuit that corrects the pressure value under set conditions when the pressure value determined by the measurement circuit is in a range greater than a set reference value; A vacuum measurement system comprising:

2. 2. The vacuum measurement system according to claim 1, A vacuum measurement system, wherein the correction circuit corrects the pressure value based on a set additional condition when the pressure value determined by the measurement circuit is in a range greater than an additional reference value that is greater than the reference value.

3. 3. The vacuum measurement system according to claim 1, a fixed electrode formed on the flat surface of the fixed portion; a movable electrode provided on the opposing surface of the diaphragm and facing the fixed electrode; Equipped with The structure prevents contact and adhesion between the fixed electrode and the movable electrode, The measurement circuit is a vacuum measurement system that converts a capacitance value between the movable electrode and the fixed electrode into the pressure value and outputs the pressure value.

4. 4. The vacuum measurement system according to claim 3, The measurement circuit converts the voltage value applied to the movable electrode and the fixed electrode into the pressure value when the voltage value is greater than the reference value, and outputs the pressure value.

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