Vacuum measurement system

Abstract

The vacuum measurement system of the present invention can measure a wider pressure range by stabilizing measurement accuracy using one sensor. The measurement circuit (104) finds the value of the pressure applied to the diaphragm (102) on the basis of the displacement of the diaphragm (102). The correction circuit (105) corrects the pressure value in a range in which the pressure value obtained by the measurement circuit (104) is larger than a set reference value under a condition set differently from a range smaller than the reference value. The set condition may be, for example, a function (conversion formula) for obtaining a correction value from a pressure value. The reference value may be, for example, a pressure value determined by the measurement circuit (104) at the time when the diaphragm (102) (movable electrode (107)) begins to come into contact with the fixed part (101) (fixed electrode (106)).

Description

Technical Field

[0001] The invention relates to a vacuum measuring system. Background Art

[0002] There is a pressure sensor comprising a first diaphragm portion in a central portion, a central thick portion surrounding the first diaphragm portion, and a second diaphragm portion around the central thick portion (Patent Document 1). The pressure sensor measures a first pressure range by displacement of the second diaphragm portion, and measures a second pressure range by displacement of the first diaphragm portion after the central thick portion abuts against a base. By providing a portion for measuring multiple pressure ranges in one sensor in this way, a wider pressure range can be measured using one sensor, thereby achieving a compact effect.

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] Patent Document 1: Japanese Patent Laid-Open No. 4-178533 Summary of the invention

[0006] [Problems to be solved by the invention]

[0007] However, with the current demand for more sophisticated control technology for semiconductor manufacturing equipment, pressure sensors are required to be more compact and to have improved stabilization of measurement accuracy.

[0008] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to stabilize the measurement accuracy and measure a wider pressure range using one sensor.

[0009] [Technical means to solve the problem]

[0010] The vacuum measuring system of the present invention includes: a fixed portion including a flat surface; a diaphragm having a flat facing surface separated from the fixed portion and opposite to the flat surface; a convex structure formed on at least one of the flat surface and the facing surface, for preventing the flat surface from contacting and fixing with the facing surface; a measuring circuit configured to calculate the pressure value applied to the diaphragm based on the displacement of the diaphragm; and a correction circuit for correcting the pressure value according to set conditions within a range in which the pressure value calculated by the measuring circuit is larger than a set reference value.

[0011] In one configuration example of the vacuum measurement system, the correction circuit corrects the pressure value according to the set additional condition within a range in which the pressure value obtained by the measurement circuit is larger than an additional reference value that is larger than the reference value.

[0012] In one structural example of the vacuum measurement system, it includes: a fixed electrode formed on a flat surface of a fixed portion; and a movable electrode arranged on the facing surface of the diaphragm and opposite to the fixed electrode. The structure prevents the fixed electrode from contacting and fixing the movable electrode. The measuring circuit converts the capacitance value between the movable electrode and the fixed electrode into a pressure value and outputs it.

[0013] In one configuration example of the vacuum measurement system, the measurement circuit converts a voltage value applied to the movable electrode and the fixed electrode into a pressure value within a range larger than a reference value and outputs the pressure value.

[0014] [Effects of the Invention]

[0015] As described above, according to the present invention, within a range where the pressure value obtained by the measuring circuit is larger than the set reference value, the pressure value is corrected according to the set conditions, so that a wider pressure range can be measured with a single sensor while stabilizing the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 : is a block diagram showing the structure of a vacuum measurement system according to an embodiment of the present invention.

[0017] Figure 2A These are explanatory diagrams for explaining each mode in the vacuum measurement system according to the embodiment of the present invention.

[0018] Figure 2B These are explanatory diagrams for explaining each mode in the vacuum measurement system according to the embodiment of the present invention.

[0019] Figure 2C These are explanatory diagrams for explaining each mode in the vacuum measurement system according to the embodiment of the present invention.

[0020] Figure 3 It is a characteristic diagram showing the change of electrostatic capacitance with respect to the pressure applied to the diaphragm 102 .

[0021] Figure 4 It is a characteristic diagram showing the change of electrostatic capacitance with respect to the pressure applied to the diaphragm 102 .

[0022] Figure 5 It is a structural diagram showing the structure of another vacuum measurement system according to the embodiment of the present invention.

[0023] Figure 6 It is a structural diagram showing the structure of another vacuum measurement system according to the embodiment of the present invention.

[0024] Figure 7 It is a structural diagram showing the structure of another vacuum measurement system according to the embodiment of the present invention.

[0025] [Explanation of Symbols]

[0026] 101: Fixed part

[0027] 102: Diaphragm

[0028] 103: Structure

[0029] 104: Measurement circuit

[0030] 105: Correction circuit

[0031] 106: Fixed electrode

[0032] 107: Movable electrode

[0033] 111: Diaphragm substrate

[0034] 112: Support

[0035] 115: Reference Room

[0036] 121: Flat surface

[0037] 122: Facing sides DETAILED DESCRIPTION

[0038] Below, refer to Figure 1 The vacuum measurement system according to the embodiment of the present invention is described below. The vacuum measurement system includes a fixing unit 101 , a diaphragm 102 , a structure 103 , a measurement circuit 104 , and a correction circuit 105 .

[0039] The fixing portion 101 includes a flat surface 121, and the diaphragm 102 includes a flat facing surface 122 facing the flat surface 121. The diaphragm 102 is formed to be spaced apart on the fixing portion 101 so as to be displaceable.

[0040] The diaphragm 102 is supported on the fixed part 101 by a support part 112 provided on the diaphragm substrate 111. In addition, a support part can be provided at a corner of the fixed part 101. For example, the fixed part 101 and the diaphragm substrate 111 are set to a square shape when viewed from above. Moreover, the fixed part 101 and the diaphragm substrate 111 can be set to a shape other than a square shape when viewed from above. Moreover, the area inside the support part 112 of the diaphragm 102 can be set to be circular when viewed from above. The fixed part 101 and the diaphragm substrate 111 (diaphragm 102) can include an insulator such as sapphire or alumina ceramics, for example. Moreover, a reference chamber 115 is formed between the fixed part 101 and the diaphragm 102. The reference chamber 115 is set to be vacuum, for example.

[0041] The structure 103 includes convex portions provided at multiple locations on the facing surface 122. The structure 103 is provided to prevent the flat surface 121 from contacting and fixing the facing surface 122. The structure 103 may include micro-pillars provided at multiple locations. By providing such a structure 103 including multiple micro-pillars, the area where the diaphragm 102 subjected to a large pressure contacts the fixing portion 101 can be reduced to the location of the structure 103. In addition, the structure can also be provided on the flat surface 121. The structure 103 may include a convex portion formed by processing the facing surface 122 of the diaphragm 102.

[0042] The measuring circuit 104 obtains the pressure value received by the diaphragm 102 based on the displacement of the diaphragm 102. In the above 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. The change in the capacitance value between the movable electrode 107 and the fixed electrode 106 caused by the displacement of the diaphragm 102 can be obtained as the change in the pressure received by the diaphragm 102. In addition, the fixed electrode 106 is formed on the flat surface 121 of the fixed part 101, and the movable electrode 107 is provided on the facing surface 122 of the diaphragm 102 and is provided in a state opposite to the fixed electrode 106.

[0043] When the structure 103 includes a convex portion formed by processing the facing surface 122 of the diaphragm 102, the movable electrode 107 can be formed on the facing surface 122 in the gap between the plurality of convex portions (micro-pillars) constituting the structure 103. The structure 103 prevents the fixed electrode 106 and the movable electrode 107 from contacting each other.

[0044] The correction circuit 105 corrects the pressure value in a range where the pressure value obtained by the measuring circuit 104 is larger than the set reference value, using conditions set differently from those in a range where the pressure value is smaller than the reference value. The set conditions may be, for example, a function (conversion formula) for obtaining the correction value based on the pressure value. The reference value may be, for example, the pressure value obtained by the measuring circuit 104 at the time when the diaphragm 102 (movable electrode 107) begins to contact the fixed part 101 (fixed electrode 106).

[0045] The vacuum measurement system of the embodiment uses FIG. 2A to FIG. 2B The first mode in which the diaphragm 102 (movable electrode 107) is measured in a state where the diaphragm 102 (movable electrode 107) is not in contact with the fixed part 101 (fixed electrode 106), and Figure 2C The second mode shown in the figure performs measurement in a state where the diaphragm 102 (movable electrode 107) is in contact with the fixed portion 101 (fixed electrode 106), thereby expanding the range of the measured pressure.

[0046] In the first mode, the measuring circuit 104 outputs the displacement state of the diaphragm 102 as a pressure value. In the second mode, after the diaphragm 102 bends and contacts the fixing part 101, the measuring circuit 104 outputs the state of the contact area as a pressure value, and the correction circuit 105 performs correction.

[0047] For example, in either the first mode or the second mode, the measuring circuit 104 converts the electrostatic capacitance between the fixed electrode 106 and the movable electrode 107 into a pressure value and outputs the result. For example, the change in electrostatic capacitance with respect to the pressure applied to the diaphragm 102 is as follows: Figure 3 As shown, the first region and the second region are different with the pressure p1 as the boundary. When the diaphragm 102 (movable electrode 107) starts to contact the fixed part 101 (fixed electrode 106), the change in the electrostatic capacitance value with respect to the pressure change becomes larger.

[0048] Thus, in the second mode, the change in electrostatic capacitance value with respect to pressure change is different from that in the first mode, and therefore the pressure value obtained by the measuring circuit 104 is corrected by the correction circuit 105. The reference value of the correction circuit 105 can be determined by experiments, etc. Figure 3 As shown, a change in the capacitance value between the fixed electrode 106 and the movable electrode 107 measured by the measurement circuit 104 is obtained and set as a pressure value of the pressure p1 at which the increase rate of the capacitance value with respect to the pressure increase changes.

[0049] Furthermore, in the second mode, which is a certain range from the diaphragm 102 (movable electrode 107) to the fixed part 101 (fixed electrode 106), the rate of increase of the capacitance value with respect to the pressure increase is greater than that in the first mode. However, if the contact area is large enough, Figure 4 As shown in the area set to the third mode, the rate of increase of the capacitance value with respect to the pressure increase becomes smaller.

[0050] In the second mode, the diaphragm 102 in the non-contact area will bend with the edge of the contact area of ​​the diaphragm 102 as a fulcrum. When the non-contact area that becomes smaller due to the increase in pressure on the diaphragm 102 approaches the displacement limit, the displacement amount in the non-contact area relative to the increase in pressure becomes smaller, and the increase rate of the contact area decreases. Figure 4 As shown, after entering the second mode, the pressure further increases and exceeds a certain pressure value p2 to enter the third mode. When the pressure application further advances, the increase rate of the capacitance value with respect to the pressure increase becomes smaller.

[0051] 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 electrode effective area, and d is the average electrode spacing. P1, P2, and P3 are the applied pressures in each mode. For the second mode, the following formula (2) holds. Similarly, for the third mode, the following formula (3) holds.

[0052] [Number 1]

[0053]

[0054] Thus, in the third mode, the change in electrostatic capacitance value with respect to pressure change is different from that in the second mode, so the pressure value obtained by the measuring circuit 104 is further corrected by the correction circuit 105, thereby enabling measurement of a higher pressure region. At this time, the correction circuit 105 corrects the pressure value with the set additional condition within the range where the pressure value obtained by the measuring circuit 104 is greater than the additional reference value greater than the reference value. The set additional condition can be set, for example, as a function (conversion formula) for obtaining a correction value based on the pressure value.

[0055] In addition, the measuring 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 within a range larger than the reference value (second mode, third mode). For example, in the second mode and the third mode, the diaphragm 102 in the area between the convex parts of multiple parts of the structure 103 is bent, and the movable electrode 107 contacts the fixed electrode 106 and a short circuit occurs between the electrodes. In this state, by reading the voltage value applied to the fixed electrode 106 and the movable electrode 107, the contact position can be determined, so by converting it into an area, it can be converted (converted) into a pressure value. It is known in advance that if the pressure relative to the diaphragm 102 is isotropic, the diaphragm 102 of uniform thickness deforms from the center and begins to contact, and each time the pressure increases, the contact area expands outward. Therefore, it is not necessary to grasp the resistance value coordinates of the contact area as a whole surface as in an electrostatic touch panel, thereby simplifying the measurement.

[0056] In addition, Figure 5 As shown, a dielectric layer 108 is 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 further increased, and the sensitivity of the electrostatic capacitance measurement can be improved.

[0057] Moreover, Figure 6As shown in FIG. 1 , a structure 103a including convex portions formed at multiple locations is arranged on the movable electrode 107. In this case, the movable electrode 107 can be formed on substantially the entire area of ​​the facing surface 122. According to the above structure, the material constituting the structure 103a can be appropriately set, and the structure 103a can be formed using 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 further increased, thereby improving the sensitivity of the electrostatic capacitance measurement.

[0058] Moreover, Figure 7 As shown, a structure 103a including convex portions formed at multiple locations is arranged on the movable electrode 107 (opposing surface 122), and a structure 103b including convex portions formed at multiple locations is arranged on the fixed electrode 106 (flat surface 121).

[0059] As described above, according to the present invention, within a range where the pressure value obtained by the measuring circuit is larger than the set reference value, the pressure value is corrected according to the set conditions, so that a wider pressure range can be measured with a single sensor while stabilizing the measurement accuracy.

[0060] In addition, the present invention is not limited to the above-described embodiments, and it is obvious that various modifications and combinations can be implemented by those skilled in the art within the technical concept of the present invention.

Claims

1. A vacuum measurement system, comprising: a fixing portion including a flat surface; a diaphragm having a flat facing surface spaced from the fixing portion and facing the flat surface; a convex structure formed on at least one of the flat surface and the facing surface, for preventing the flat surface from contacting and fixing with the facing surface; a measuring circuit configured to obtain a pressure value applied to the diaphragm based on a displacement of the diaphragm; as well as The correction circuit corrects the pressure value according to a set condition within a range where the pressure value obtained by the measurement circuit is larger than a set reference value.

2. The vacuum measurement system according to claim 1, wherein The correction circuit corrects the pressure value according to the set additional condition within a range in which the pressure value obtained by the measurement circuit is larger than an additional reference value that is larger than the reference value.

3. The vacuum measurement system according to claim 1 or 2, comprising: a fixed electrode formed on the flat surface of the fixed portion; as well as a movable electrode provided on the facing surface of the diaphragm and facing the fixed electrode, The structure prevents the fixed electrode from contacting and fixing with the movable electrode. The measurement circuit converts the capacitance value between the movable electrode and the fixed electrode into the pressure value and outputs the pressure value.

4. The vacuum measurement system according to claim 3, wherein The measurement circuit converts the voltage value applied to the movable electrode and the fixed electrode into the pressure value within a range larger than the reference value, and outputs the pressure value.

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