Fluid control valve

Abstract

To provide a fluid control valve capable of suppressing deformation of an annular valve seat even under a high-temperature condition, thereby preventing deterioration of sealing performance and fatigue damage of a diaphragm member.SOLUTION: In a fluid control valve 1 that comprises a pressing member (e.g., a second stem 32), a diaphragm member 34, and a valve seat 33, and in which the pressing member (second stem 32) presses and deforms the diaphragm member 34 to abut against the valve seat 33, the valve seat 33 comprises a first annular valve seat 331 made of fluororesin and a second annular valve seat 332 made of heat-resistant resin, which are coaxially adjacent to each other, where the heat-resistant resin has a deflection temperature under load at 1.82 MPa measured in accordance with ASTM D-648 that is higher than that of the fluororesin.SELECTED DRAWING: Figure 2

Description

Technical Field

[0004] , ,

[0001] The present invention relates to a fluid control valve including a pressing member, a diaphragm member, and a valve seat, wherein the pressing member presses and deforms the diaphragm member to bring it into contact with the valve seat.

Background Art

[0002] In film formation processes in semiconductor manufacturing processes, a plurality of types of process gases are used. To control the flow rate of this process gas, a fluid control valve is used. As the fluid control valve, for example, the fluid control valves disclosed in Patent Document 1 and Patent Document 2 are known. The fluid control valve disclosed in Patent Document 1 is an air-operated on-off valve that controls the flow rate of the process gas by bringing a diaphragm member into contact with and separating from a valve seat.

[0003] More specifically, it will be described with reference to FIGS. 5 to 7. FIG. 5 is a cross-sectional view of a fluid control valve 100 according to the prior art, showing the valve open state of the fluid control valve 100. FIG. 6 is a cross-sectional view of the fluid control valve 100 according to the prior art, showing the valve closed state of the fluid control valve 100. FIG. 7 is a partially enlarged view of part C in FIG. 6. <0​​​​​​The process gas used in atomic layer deposition (ALD), a thin-film deposition technology that has become widespread in recent years, can be at high temperatures of 250°C or higher. In this case, the diaphragm member 34 and the valve seat 101 may both be made of metal to ensure heat resistance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-180490 [Patent Document 2] Japanese Patent Publication No. 2017-223318 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] When both the diaphragm member 34 and the valve seat 101 are made of metal, the contact between the diaphragm member 34 and the valve seat 33 is metal-to-metal contact, making it prone to wear. In particular, fluid control valves used in ALDs need to repeatedly perform contact and separation operations at a very high frequency, so the fluid control valve 100 may need to be replaced with a new one within a few months of being put into use.

[0008] To prevent wear due to metal-to-metal contact, the valve seat 101 may be made of a fluororesin with excellent chemical resistance. However, the deflection temperature at 1.82 MPa, measured in accordance with ASTM D-648 for fluororesin, is approximately 50 degrees Celsius. Therefore, under high-temperature conditions where the process gas temperature is 250°C or higher, the valve seat 101 is prone to deformation. Consequently, under high-temperature conditions, if the diaphragm member 34 repeatedly contacts and separates from the fluororesin valve seat 101, the valve seat 101 may be compressed beyond its design value by the diaphragm member 34, as shown in Figure 7, for example, potentially reducing the dimension in the contact-to-separation direction (valve seat height dimension). When the valve seat 101 is excessively compressed in this way, the surface pressure when the diaphragm member 34 contacts it decreases, which can lead to a decrease in the sealing performance of the fluid control valve 100. In addition, if the height dimension of the valve seat 101 is reduced, the amount of deformation (stroke) of the diaphragm member 34 before it contacts the valve seat 101 when moving the fluid control valve 100 from the open state to the closed state will be greater than the design value. If the amount of deformation of the diaphragm member 34 is greater than the design value, fatigue failure of the diaphragm member 34 may occur more easily.

[0009] The present invention has been made in view of the above problems, and aims to provide a fluid control valve that can prevent a decrease in sealing performance and fatigue failure of the diaphragm member by suppressing deformation of the annular valve seat even under high-temperature conditions. [Means for solving the problem]

[0010] To solve the above problems, a fluid control valve in one aspect of the present invention has the following configuration.

[0011] (1) A fluid control valve comprising a pressing member, a diaphragm member, and a valve seat, wherein the pressing member presses and deforms the diaphragm member to bring it into contact with the valve seat, wherein the valve seat comprises a first annular valve seat made of fluororesin and a second annular valve seat made of heat-resistant resin, both located coaxially adjacent, and the heat-resistant resin has a load deflection temperature at 1.82 MPa, measured in accordance with ASTM D-648, that is higher than that of the fluororesin. The upper end surface of the first annular valve seat facing the diaphragm member and the upper end surface of the second annular valve seat facing the diaphragm member form contact surfaces for the diaphragm member to come into contact with and separate from each other. It is characterized by the following.

[0012] According to the fluid control valve described in (1) above, the sealing performance when the valve is closed is mainly ensured by the first annular valve seat made of fluororesin. The first annular valve seat is made of fluororesin, so when the diaphragm member comes into contact with it, it conforms easily to the shape of the diaphragm member and has good transferability. The second annular valve seat is made of a heat-resistant resin that has a higher load deflection temperature than fluororesin, so it is less prone to deformation than fluororesin even under high temperature conditions. Therefore, the second annular valve seat mainly plays the role of receiving the load applied from the diaphragm member. By the second annular valve seat receiving the load applied from the diaphragm member at a position adjacent to the first annular valve seat, it is possible to prevent the first annular valve seat from being excessively crushed by the load. This prevents an increase in the amount of deformation (stroke) of the diaphragm member before it comes into contact with the annular valve seat due to the crushing of the valve seat, and consequently prevents a decrease in the sealing performance of the fluid control valve and the occurrence of fatigue failure in the diaphragm member. Examples of fluororesins include perfluoroalkoxyalkanes (PFA), polytetrafluoroethylene (PTFE), and perfluoroelastomers (FFKM).

[0013] (2) In the fluid control valve described in (1), it is preferable that the heat-resistant resin has a load deflection temperature of 125°C or higher at 1.82 MPa, as measured in accordance with ASTM D-648.

[0014] (3) In the fluid control valve according to (1) or (2), it is preferable that the heat-resistant resin is any one of polyether ether ketone (PEEK), polyether ketone (PEK), polybenzimidazole (PBI), polyimide (PI), and high heat-resistant polyamide (PA).

[0015] According to the fluid control valve described in (2) or (3) above, even under a high-temperature condition where the temperature of the process gas is 250°C or higher, deformation of the second annular valve seat can be prevented. Therefore, the second annular valve seat can surely receive the load applied from the diaphragm member, and it can surely prevent the first annular valve seat from being excessively crushed.

Effects of the Invention

[0016] According to the fluid control valve of the present invention, even under high-temperature conditions, by suppressing deformation of the valve seat, it is possible to prevent deterioration of sealing performance and prevent fatigue failure of the diaphragm member.

Brief Description of the Drawings

[0017] [Figure 1] It is a cross-sectional view of the fluid control valve according to the present embodiment, showing the valve-open state of the fluid control valve. [Figure 2] It is a partial enlarged view of part A in FIG. 1. [Figure 3] It is a cross-sectional view of the fluid control valve according to the present embodiment, showing the valve-closed state of the fluid control valve. [Figure 4] It is a partial enlarged view of part B in FIG. 3. [Figure 5] It is a cross-sectional view of the fluid control valve according to the prior art, showing the valve-open state of the fluid control valve. [Figure 6] It is a cross-sectional view of the fluid control valve according to the prior art, showing the valve-closed state of the fluid control valve. [Figure 7] It is a partial enlarged view of part C in FIG. 6.

Modes for Carrying Out the Invention

[0018] An embodiment of the fluid control valve according to the present invention will be described in detail with reference to the drawings. The drawings used in the description are simplified for the purpose of explanation and do not accurately represent the shape, dimensions, etc.

[0019] (Regarding the configuration of the fluid control valve) The configuration of the fluid control valve 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the fluid control valve 1 according to the present embodiment, showing the valve open state of the fluid control valve 1. FIG. 2 is a partial enlarged view of part A in FIG. 1. FIG. 3 is a cross-sectional view of the fluid control valve 1 according to the present embodiment, showing the valve closed state of the fluid control valve 1. FIG. 4 is a partial enlarged view of part B in FIG. 3.

[0020] The fluid control valve 1 is a gas valve disposed in the gas supply system of a semiconductor manufacturing apparatus and is used to control the supply of a process gas at a high temperature (for example, about 250°C). The fluid control valve 1 is a normally closed type air-operated on-off valve and includes a drive unit 2 and a valve unit 3 as shown in FIG. 1. Further, the drive unit 2 includes an actuator unit 4 and a spring unit 5.

[0021] First, the actuator unit 4 will be described. The actuator unit 4 is a pneumatically driven air cylinder. The actuator unit 4 includes a cylindrical case 41, a piston (not shown) loaded inside the case 41, and a cylindrical drive shaft 42 coupled to the piston. Further, the actuator unit 4 includes a pilot port 44 for inputting operating air into the case 41 at an end of the case 41 opposite to the spring unit 5 (the upper end in FIG. 1).

[0022] The piston is made able to slide vertically within the case 41 by supplying or stopping operating air from the pilot port 44 into the case 41. As the piston moves up and down, the drive shaft 62 moves back and forth along its axial direction. The axial direction of the drive shaft 62 is parallel to the vertical direction in Figure 1 and coincides with the direction in which the diaphragm member 34, described later, contacts and separates from the valve seat 33. In the figure, the upper side is the separation direction and the lower side is the contact direction.

[0023] The end of the drive shaft 42 on the valve section 3 side (the lower end in Figure 1) protrudes from the actuator section 4 and extends into the spring section 5. A first stem 43 is provided at the tip of the drive shaft 42 within the spring section 5. Therefore, as the drive shaft 42 moves back and forth, the first stem 43 also moves back and forth in the same direction. The end face of the first stem 43 opposite to the drive shaft 42 abuts against the second stem 32, which will be described later. As a result, when the first stem 43 is driven in the abutment direction, the first stem 43 presses against the second stem 32 in the abutment direction.

[0024] Next, the spring section 5 will be described. The spring section 5 includes a compression coil spring 52 located coaxially with the operating rod 9 in the internal space 51. The compression coil spring 52 is compressed between the end face 53 on the actuator section 4 side of the internal space 51 and the first stem 43. As a result, the compression coil spring 52 constantly biases the first stem 43 in the contact direction (downward in the figure).

[0025] Next, the valve section 3 will be described. The valve section 3 comprises a body 31, a second stem 32 (an example of a pressing member), a valve seat 33, and a diaphragm member 34. The body 31 has a cylindrical portion 315 that connects to the spring section 5. In addition, a valve chamber 311 is drilled inside the cylindrical portion 315 of the body 31.

[0026] A valve port 312 for inputting process gas into the valve chamber 311 is provided in the center of the bottom of the valve chamber 311. Furthermore, an annular valve seat 33 is fixed to the bottom surface of the valve chamber 311, on the outer circumference of the valve port 312 and coaxial with the valve port 312. The valve chamber 311 also communicates with an output flow path 314 radially outside the valve seat 33. This output flow path 314 is used to output process gas from the valve chamber 311.

[0027] The second stem 32 is made of, for example, stainless steel. The second stem 32 is formed in a substantially cylindrical shape, and the surface facing the diaphragm member 34 (the lower end surface in the figure) is a spherical surface 321 that bulges out toward the diaphragm member 34. The second stem 32 is held by a holder 35 so that the spherical surface 321 is in contact with the diaphragm member 34 and is able to move up and down.

[0028] The diaphragm member 34 is made of, for example, a Ni alloy. The diaphragm member 34 is formed in a spherical shape that bulges out toward the second stem 32. Therefore, the opposing surface 341 of the diaphragm member 34 that faces the second stem 32 is spherical. The surface of the diaphragm member 34 opposite to the opposing surface 341 is the back surface 342. The diaphragm member 34 also has a planar edge portion 344 on its outer periphery that is perpendicular to the direction of contact and separation. This edge portion 344 is held between the holder 35 and the body 31, thereby fixing the diaphragm member 34 to the valve chamber 311. With the diaphragm member 34 fixed in this way, when pressed by the second stem 32, the central part is elastically deformed in the direction of contact along the spherical surface 321 of the second stem 32. When the pressure from the second stem 32 is released, it returns to its original spherical shape due to its self-restoring force.

[0029] The valve seat 33 consists of a first annular valve seat 331 made of fluororesin and a second annular valve seat 332 made of a heat-resistant resin. Examples of fluororesins that form the first annular valve seat 331 include perfluoroalkoxyalkanes (PFA), polytetrafluoroethylene (PTFE), and perfluoroelastomers (FFKM). The heat-resistant resin that forms the second annular valve seat 332 preferably has a load deflection temperature at 1.82 MPa (hereinafter simply referred to as "load deflection temperature") measured in accordance with ASTM D-648, which is higher than approximately 50-55°C of the load deflection temperature of the above fluororesin, and more preferably 125°C or higher. Specifically, examples include polyetheretherketone (PEEK), polyetherketone (PEK), polybenzimidazole (PBI), polyimide (PI), and high heat-resistant polyamide (PA). The deflection temperatures are as follows: PEEK is 155°C, PEK is 180°C, PBI is 410°C, PI is 360°C, and PA is 125°C.

[0030] The first annular valve seat 331 and the second annular valve seat 332 are both formed in an annular shape and are located adjacent to each other on the same axis. More specifically, the first annular valve seat 331 is located on the outer circumference side and the second annular valve seat 332 is located on the inner circumference side, with the inner surface of the first annular valve seat 331 and the outer surface of the second annular valve seat 332 in contact with each other. The crimping portion 316 provided on the body 31 presses down on the first annular valve seat 331 from the outer circumference side, thereby fixing the first annular valve seat 331 and the second annular valve seat 332 to the bottom surface of the valve chamber 311.

[0031] Furthermore, since the first annular valve seat 331 and the second annular valve seat 332 are located adjacent to each other on the same axis, the upper end surface 331a of the first annular valve seat 331 facing the diaphragm member 34 and the upper end surface 332a of the second annular valve seat 332 facing the diaphragm member 34 form the contact surface 33a of the valve seat 33 for the diaphragm member 34 to contact and separate from each other. Therefore, when the diaphragm member 34 contacts the valve seat 33, the load applied to the valve seat 33 can be received by the first annular valve seat 331 and the second annular valve seat 332.

[0032] In this embodiment, the first annular valve seat 331 is positioned on the outer circumference and the second annular valve seat 332 is positioned on the inner circumference. However, the first annular valve seat 331 may be positioned on the inner circumference and the second annular valve seat 332 on the outer circumference. In this embodiment, the first annular valve seat 331 is positioned on the outer circumference and the second annular valve seat 332 is positioned on the inner circumference in order to securely fix the valve seat 33. To explain in more detail, since the crimping portion 316 is located on the outer circumference of the valve seat 33, when the crimping portion 316 presses down on the valve seat 33, the crimping portion 316 can bite into the valve seat 33 more easily when the first annular valve seat 331, which has lower hardness, is positioned on the outer circumference, thus ensuring that the valve seat 33 is securely fixed.

[0033] (Regarding the operation of fluid control valves) Next, the operation of the fluid control valve 1 will be explained.

[0034] When operating air is supplied from the pilot port 44 to the actuator unit 4, the piston inside the case 41 moves in the opposite direction. Consequently, the drive shaft 62 is driven in the same direction. Since the first stem 43 is connected to the drive shaft 62, it rises against the elastic force of the compression coil spring 52. As a result, the second stem 32, which was being held down by the first stem 43, rises due to the restoring force of the diaphragm member 34. The diaphragm member 34 separates from the valve seat 33, and the fluid control valve 1 enters the open state, as shown in Figure 1. In this open state, process gas flows from the valve port 312 into the valve chamber 311 and is then output to the output flow path 314.

[0035] On the other hand, when the supply of operating air to the pilot port 44 is stopped, the elastic force of the compression coil spring 52 drives the first stem 43 in the contact direction. The first stem 43 moves in the same direction by pressing against the second stem 32. As the second stem 32 moves, the diaphragm member 34 comes into contact with the valve seat 33, and the fluid control valve 1 enters a closed state, as shown in Figure 3. In the closed state, the flow of process gas from the valve port 312 to the valve chamber 311 is blocked.

[0036] (Regarding the effects and benefits) As described above, the fluid control valve 1 according to this embodiment is (1) A fluid control valve 1 comprising a pressing member (for example, a second stem 32), a diaphragm member 34, and a valve seat 33, wherein the pressing member (second stem 32) presses and deforms the diaphragm member 34 to bring it into contact with the valve seat 33, wherein the valve seat 33 comprises a first annular valve seat 331 made of fluororesin and a second annular valve seat 332 made of heat-resistant resin, which are located coaxially adjacent to each other, and the heat-resistant resin has a load deflection temperature at 1.82 MPa measured in accordance with ASTM D-648 that is higher than that of the fluororesin.

[0037] According to the fluid control valve 1 described in (1) above, the sealing performance when the valve is closed is mainly ensured by the first annular valve seat 331 made of fluororesin. The first annular valve seat 331 is made of fluororesin, so when the diaphragm member 34 comes into contact with it, it conforms easily to the shape of the diaphragm member 34 and has good transferability. The second annular valve seat 332 is made of a heat-resistant resin that has a higher load deflection temperature than fluororesin, so it is less prone to deformation than fluororesin even under high temperature conditions. Therefore, the second annular valve seat 332 mainly plays the role of receiving the load applied from the diaphragm member 34. By having the second annular valve seat 332 receive the load applied from the diaphragm member 34 at a position adjacent to the first annular valve seat 331, it is possible to prevent the first annular valve seat 331 from being excessively crushed by the load applied from the diaphragm member, even if the above contact and separation operation is repeated.

[0038] Furthermore, the fluid control valve 1 may be annealed in the closed state before use. This annealing process allows the contact surface 33a to conform to the back surface 342 of the diaphragm member 34 in the closed state. During this annealing process, while the diaphragm member 34 is in contact with the valve seat 33, the load applied to the valve seat 33 is received by the second annular valve seat 332, which is made of heat-resistant resin, along with the first annular valve seat 331, thus preventing the first annular valve seat 331 from being excessively crushed.

[0039] As described above, by preventing the collapse of the valve seat 33 (first annular valve seat 331), it is possible to prevent an increase in the amount of deformation (stroke) of the diaphragm member before it contacts the annular valve seat due to the collapse of the valve seat, and consequently, to prevent a decrease in the sealing performance of the fluid control valve and the occurrence of fatigue failure in the diaphragm member.

[0040] (2) In the fluid control valve 1 described in (1), it is preferable that the heat-resistant resin has a load deflection temperature of 125°C or higher at 1.82 MPa, as measured in accordance with ASTM D-648.

[0041] (3) In the fluid control valve 1 described in (1) or (2), it is preferable that the heat-resistant resin is one of the following: polyether ether ketone (PEEK), polyether ketone (PEK), polybenzimidazole (PBI), polyimide (PI), or high heat-resistant polyamide (PA).

[0042] According to the fluid control valve 1 described in (2) or (3) above, deformation of the second annular valve seat 332 can be prevented even under high-temperature conditions where the process gas temperature is 250°C or higher. Therefore, the second annular valve seat 332 can reliably withstand the load applied from the diaphragm member 34, and the first annular valve seat 331 can be reliably prevented from being excessively crushed.

[0043] The above embodiments are merely illustrative and do not limit the present invention in any way. Therefore, the present invention can naturally be improved and modified in various ways without departing from its essence. For example, in the fluid control valve 1 according to this embodiment, a pneumatically driven air cylinder is used as the drive unit 2, but other drive sources such as a linear servo motor may be used. [Explanation of Symbols]

[0044] 1. Fluid control valve 32. Second stem (an example of a pressing member) 33 valve seats 34 Diaphragm component 331 First annular valve seat 332 Second annular valve seat 332

Claims

1. It comprises a pressing member, a diaphragm member, and a valve seat. In a fluid control valve in which the pressing member presses and deforms the diaphragm member to bring it into contact with the valve seat, The valve seat comprises a first annular valve seat made of fluororesin and a second annular valve seat made of heat-resistant resin, both located coaxially adjacent to each other. The heat-resistant resin has a higher deflection temperature at 1.82 MPa than the fluororesin, as measured in accordance with ASTM D-648. The upper end surface of the first annular valve seat facing the diaphragm member and the upper end surface of the second annular valve seat facing the diaphragm member form contact surfaces for the diaphragm member to come into contact with and separate from each other. A fluid control valve characterized by the following.

2. In the fluid control valve according to claim 1, The heat-resistant resin has a load deflection temperature of 125°C or higher at 1.82 MPa, as measured in accordance with ASTM D-648. A fluid control valve characterized by the following.

3. In the fluid control valve according to claim 1 or 2, The heat-resistant resin is one of the following: polyether ether ketone, polyether ketone, polybenzimidazole, polyimide, or high heat-resistant polyamide. A fluid control valve characterized by the following.

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