pressure sensor

Abstract

To stabilize measurement precision of a pressure sensor for switching an area of a diaphragm used for measurement.SOLUTION: A pressure sensor includes: a pedestal 101; a diaphragm 102; a structure 103; a first switch electrode 105a; a second switch electrode 105b; a switch conductor 105c; and a measurement portion 120. The structure 103 is provided in a boundary between a first area 102a and a second area 102b on a surface in a side of the pedestal 101 of the diaphragm 102 and projects to a side of the pedestal 101 and is formed in a projection shape. The first switch electrode 105a, the second switch electrode 105b, and the switch conductor 105c compose a detection portion for detecting abutting of the structure 103 on the pedestal 101 after the diaphragm 102 is displaced to a side of the pedestal 101.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pressure sensor.

Background Art

[0002] There is a pressure sensor including a first diaphragm portion at the center, a central thick portion surrounding 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 due to the displacement of the second diaphragm portion, and after the central thick portion abuts against the pedestal, it measures a second pressure range due to the displacement of the first diaphragm portion. By providing a portion for measuring a plurality of pressure ranges in one sensor in this way, the effect of miniaturization can be obtained.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, currently, with the increasing demand for advanced control technology of semiconductor manufacturing equipment, in addition to miniaturization, improvements in the stabilization of measurement accuracy are required for pressure sensors.

[0005] The present invention has been made to solve the above problems and aims to stabilize the measurement accuracy of a pressure sensor that switches the area of the diaphragm used for measurement.

Means for Solving the Problems

[0006] The pressure sensor according to the present invention comprises a diaphragm formed on a base and made displaceable, having a first region in the center and a second region surrounding the first region, which receives the pressure of the gas to be measured; a convex structure provided at the boundary between the first region and the second region on the base-side surface of the diaphragm and projecting toward the base; a detection unit configured to detect when the diaphragm is displaced toward the base and the structure comes into contact with the base; and a measurement unit configured to determine a first pressure value received by the first region by measuring the displacement of the first region and a second pressure value received by the second region by measuring the displacement of the second region. When the detection unit detects that the structure has come into contact with the base, the measurement unit changes the output from the second pressure value to the first pressure value.

[0007] In one example of the configuration of the pressure sensor described above, the detection unit includes a first switch electrode and a second switch electrode provided on a base, and a switch conductor provided at the tip of the structure that short-circuits the first switch electrode and the second switch electrode when the structure comes into contact with the base.

[0008] In one example of the configuration of the pressure sensor described above, a first movable electrode is formed on the side surface of the base in the first region of the diaphragm, a first fixed electrode is provided on the surface of the base and faces the first movable electrode, a second movable electrode is formed on the side surface of the base in the second region of the diaphragm, and a second fixed electrode is provided on the surface of the base and faces the second movable electrode.

[0009] In one example of the configuration of the pressure sensor described above, a reference electrode is further provided, which is formed around the second fixed electrode on the surface of the base and faces the second movable electrode.

[0010] In one example of the pressure sensor configuration described above, the measuring unit converts the change in capacitance between the first movable electrode and the first fixed electrode due to the displacement of the diaphragm into a first pressure value and outputs it, and uses the capacitance between the second movable electrode and the reference electrode as a reference, converts the change in capacitance between the second movable electrode and the second fixed electrode due to the displacement of the diaphragm into a second pressure value and outputs it. [Effects of the Invention]

[0011] As described above, according to the present invention, a convex structure provided at the boundary between the first region and the second region on the side surface of the diaphragm base and protruding toward the base is detected to come into contact with the base, thereby stabilizing the measurement accuracy of the pressure sensor that switches the region of the diaphragm used for measurement. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a cross-sectional view showing the configuration of a pressure sensor according to Embodiment 1 of the present invention. [Figure 2A] Figure 2A is a plan view showing a partial configuration of a pressure sensor according to Embodiment 1 of the present invention. [Figure 2B] Figure 2B is a plan view showing a partial configuration of a pressure sensor according to Embodiment 1 of the present invention. [Figure 3] Figure 3 is a cross-sectional view showing the configuration of a pressure sensor according to Embodiment 2 of the present invention. [Modes for carrying out the invention]

[0013] The following describes a pressure sensor according to an embodiment of the present invention.

[0014] [Embodiment 1] First, a pressure sensor according to Embodiment 1 of the present invention will be described with reference to Figure 1. This pressure sensor comprises a base 101, a diaphragm 102, a structure 103, a first switch electrode 105a, a second switch electrode 105b, a switch conductor 105c, and a measuring unit 120.

[0015] The diaphragm 102 is displaceable and formed on the base 101. The diaphragm 102 has a central first region 102a and a second region 102b surrounding the first region 102a, and receives the pressure of the gas being measured. The diaphragm 102 has an opposing surface that is spaced apart from the surface of the base 101 and faces the base 101. The opposing surface of the diaphragm 102 is positioned spaced apart from the base 101, and the diaphragm 102 is displaceable in the direction normal to the plane of the base 101. The diaphragm 102 displaces when it receives pressure from the gas being measured. For example, the first region 102a is formed to be thicker than the second region 102b. A reference chamber 115 is formed between the base 101 and the opposing surface of the diaphragm 102. The reference chamber 115 is, for example, a vacuum.

[0016] The diaphragm 102 is supported on the base 101 by a support portion 112 provided on the diaphragm substrate 111. The support portion 112 of the diaphragm substrate 111 and the base 101 are joined at a joint portion 113 on the outer circumference of the diaphragm 102. A support portion can also be provided on the base 101. For example, the base 101 and the diaphragm substrate 111 are square in plan view. However, they may have shapes other than square in plan view. Also, the area inside the support portion 112 of the diaphragm 102 is circular in plan view. The base 101 and the diaphragm substrate 111 can be made of an insulator such as sapphire or alumina ceramic.

[0017] The structure 103 is provided at the boundary between the first region 102a and the second region 102b on the surface of the base 101 side of the diaphragm 102, and protrudes toward the base 101 side and is formed in a convex shape. The first switch electrode 105a and the second switch electrode 105b are provided at positions facing the formation position of the structure 103 on the base 101. The switch conductor 105c is provided at the tip of the structure 103. When the structure 103 abuts against the base 101, the first switch electrode 105a and the second switch electrode 105b are short-circuited by the switch conductor 105c. The first switch electrode 105a, the second switch electrode 105b, and the switch conductor 105c constitute a detection unit that detects that the diaphragm 102 has displaced toward the base 101 side and the structure 103 has abutted against the base 101.

[0018] The measurement unit 120 obtains the first pressure value received by the first region 102a by measuring the displacement of the first region 102a, and obtains the second pressure value received by the second region 102b by measuring the displacement of the second region 102b. When the detection unit detects that the structure 103 has abutted against the base 101, the measurement unit 120 changes from the output of the second pressure value to the output of the first pressure value.

[0019] In Embodiment 1, the pressure sensor includes a first movable electrode 106, a first fixed electrode 107, a second movable electrode 108, and a second fixed electrode 109. The first movable electrode 106 is formed on the surface (opposing surface) of the first region 102a of the diaphragm 102 on the base 101 side. The first fixed electrode 107 is provided on the surface of the base 101 and is arranged facing the first movable electrode 106.

[0020] The second movable electrode 108 is formed on the surface (opposing surface) of the second region 102b of the diaphragm 102 on the base 101 side. The second fixed electrode 109 is provided on the surface of the base 101 and is arranged facing the second movable electrode 108. The movable electrode and the fixed electrode form a capacitance. This capacitance changes when the diaphragm 102 is displaced (flexed). As is well known, a capacitive pressure sensor measures the pressure received by the diaphragm 102 based on the change in the capacitance formed between the fixed electrode and the movable electrode.

[0021] The measuring unit 120 converts the capacitance change between the first movable electrode 106 and the first fixed electrode 107 due to the displacement of the diaphragm 102 into a first pressure value and outputs it. Further, the measuring unit 120 uses the capacitance between the second movable electrode 108 and the reference electrode as a reference, and converts the capacitance change between the second movable electrode 108 and the second fixed electrode 109 due to the displacement of the diaphragm 102 into a second pressure value and outputs it.

[0022] For example, when the pressure applied to the diaphragm 102 reaches a certain pressure value from the state where the diaphragm 102 is not under pressure, the tip of the structure 103 abuts on the base 101 due to the displacement of the diaphragm 102. This state is detected by the short - circuiting of the first switch electrode 105a and the second switch electrode 105b by the switch conductor 105c.

[0023] Until the tip of the structure 103 abuts on the base 101, the outer periphery of the diaphragm 102 (support portion 112) serves as a fixed support end and the diaphragm 102 is deformed. After the tip of the structure 103 abuts on the base 101, the structure 103 serves as a fixed support end and the diaphragm 102 is deformed.

[0024] In the first region 102a and the second region 102b, due to the difference in area or thickness, the amount of displacement with respect to the applied pressure before and after the abutment of the structure 103 is different. Since the deflection (amount of displacement) is proportional to the square of the area and the cube of the thickness, low - pressure measurement before the first region 102a abuts is enabled, and high - pressure measurement after the second region 102b abuts is enabled. Further, since it is detected that the structure 103 has abutted on the base 101, the switching timing can be known, so that appropriate arithmetic switching of the pressure value can be performed, and the effect of stabilizing the measurement accuracy can be obtained.

[0025] As shown in FIG. 2A, the structure 103 can be in a standing - up shape. Also, as shown in FIG. 2B, the structure 103 can be in a cylindrical shape. Also, a plurality of structures 103 can be provided.

[0026] [Embodiment 2] Next, a pressure sensor according to Embodiment 2 of the present invention will be described with reference to Figure 3. This pressure sensor comprises a base 101, a diaphragm 102, a structure 103, a first switch electrode 105a, a second switch electrode 105b, and a switch conductor 105c. The pressure sensor also comprises a first movable electrode 106, a first fixed electrode 107, a second movable electrode 108, and a second fixed electrode 109. These configurations are the same as those of Embodiment 1 described above.

[0027] In Embodiment 2, a reference electrode 110 is formed around the second fixed electrode 109 on the surface of the base 101 and faces the second movable electrode 108. The measuring unit 120a converts the change in capacitance between the first movable electrode 106 and the first fixed electrode 107 due to the displacement of the diaphragm 102 into a first pressure value and outputs it. The measuring unit 120a also uses the capacitance between the second movable electrode 108 and the reference electrode 110 as a reference and converts the change in capacitance between the second movable electrode 108 and the second fixed electrode 109 due to the displacement of the diaphragm 102 into a second pressure value and outputs it.

[0028] In the second embodiment, for example, when the pressure on the diaphragm 102 reaches a certain pressure value, the tip of the structure 103 comes into contact with the base 101 due to the displacement of the diaphragm 102. This state is detected by the fact that the first switch electrode 105a and the second switch electrode 105b are short-circuited by the switch conductor 105c.

[0029] Until the tip of the structure 103 contacts the base 101, the outer circumference (support portion 112) of the diaphragm 102 acts as a fixed support end, causing the diaphragm 102 to deform. After the tip of the structure 103 contacts the base 101, the structure 103 acts as a fixed support end, causing the diaphragm 102 to deform. Due to the difference in area or thickness between the first region 102a and the second region 102b, the amount of displacement in response to the applied pressure differs before and after contact with the structure 103. Since deflection (amount of displacement) is proportional to the square of the area and the cube of the thickness, low-pressure measurement is possible before contact with the first region 102a, and high-pressure measurement is possible after contact with the second region 102b. Furthermore, according to the second embodiment, the change in capacitance between the second movable electrode 108 and the second fixed electrode 109 is measured based on the capacitance between the second movable electrode 108 and the reference electrode 110, thus suppressing measurement variations.

[0030] As described above, according to the present invention, a convex structure provided at the boundary between the first region and the second region on the side surface of the diaphragm base and protruding toward the base is detected to contact the base, thereby stabilizing the measurement accuracy of the pressure sensor that switches the region of the diaphragm used for measurement.

[0031] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be implemented within the technical concept of the present invention by those with ordinary skill in the art. [Explanation of symbols]

[0032] 101...Base, 102...Diaphragm, 102a...First region, 102b...Second region, 103...Structure, 105a...First switch electrode, 105b...Second switch electrode, 105c...Switch conductor, 106...First movable electrode, 107...First fixed electrode, 108...Second movable electrode, 109...Second fixed electrode, 111...Diaphragm substrate, 112...Support part, 113...Joint part, 115...Reference chamber, 120...Measurement part.

Claims

1. A diaphragm formed on a base and made displaceable, having a first region in the center and a second region surrounding the first region, which receives the pressure of the gas to be measured, A convex structure is provided at the boundary between the first region and the second region on the base side surface of the diaphragm and protrudes toward the base side, A detection unit configured to detect that the diaphragm has been displaced toward the base and that the structure has come into contact with the base, A measuring unit configured to determine a first pressure value received by the first region by measuring the displacement of the first region, and to determine a second pressure value received by the second region by measuring the displacement of the second region. Equipped with, When the detection unit detects that the structure has come into contact with the base, the measurement unit changes the output from the second pressure value to the first pressure value. A pressure sensor characterized by the following features.

2. In the pressure recovery according to claim 1, The detection unit is The base is provided with a first switch electrode and a second switch electrode, A switch conductor is provided at the tip of the structure, which short-circuits the first switch electrode and the second switch electrode when the structure contacts the base. A pressure sensor characterized by comprising the following features.

3. In the pressure sensor according to claim 1 or 2, A first movable electrode formed on the side surface of the base of the first region of the diaphragm, A first fixed electrode is provided on the surface of the base and faces the first movable electrode, A second movable electrode formed on the side surface of the base of the second region of the diaphragm, A second fixed electrode is provided on the surface of the base and faces the second movable electrode. A pressure sensor characterized by comprising the following features.

4. In the pressure detection method according to claim 3, A pressure sensor further comprising a reference electrode formed around the second fixed electrode on the surface of the base and facing the second movable electrode.

5. In the pressure sensor according to claim 4, The aforementioned measuring unit is The change in capacitance between the first movable electrode and the first fixed electrode due to the displacement of the diaphragm is converted into a first pressure value and output. Based on the capacitance between the second movable electrode and the reference electrode, the capacitance change between the second movable electrode and the second fixed electrode due to the displacement of the diaphragm is converted into the second pressure value and output. A pressure sensor characterized by the following features.

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