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]

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

[0002] A plurality of types of process gases are used in the film formation process in the semiconductor manufacturing process. A fluid control valve is used to control the flow rate of the process gas. For example, the fluid control valves disclosed in Patent Document 1 and Patent Document 2 are known as fluid control valves. 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, the description will be given with reference to Figures 5 to 7. Figure 5 is a cross-sectional view of a conventional fluid control valve 100, showing the fluid control valve 100 in an open state. Figure 6 is a cross-sectional view of a conventional fluid control valve 100, showing the fluid control valve 100 in a closed state. Figure 7 is a partial enlarged view of part C in Figure 6.

[0004] As shown in FIG. 5, in the fluid control valve 100, the stem 32 is in contact with the apex of the diaphragm member 34 formed in a spherical crown shape. Then, the stem 32 presses the diaphragm member 34 downward in the figure by the operation of the actuator unit 4 (for example, an air cylinder) or the biasing force of the compression coil spring 52 in the spring unit 5, deforming it and causing it to abut against the annular valve seat 101. As shown in FIG. 6, the state in which the diaphragm member 34 abuts against the valve seat 101 is the valve closed state of the fluid control valve 100. Then, when the pressing of the diaphragm member 34 by the stem 32 is released, the diaphragm member 34 returns to its original spherical crown shape by its self-restoring force and moves away from the valve seat 101. As shown in FIG. 5, the state in which the diaphragm member 34 moves away from the valve seat 101 is the valve open state of the fluid control valve 100.

[0005] The process gases used in atomic layer deposition (ALD), a film formation technology that has become widespread in recent years, can be as hot as 250°C or more. In such cases, 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] JP 2016-180490 A [Patent Document 2] JP 2017-223318 A Summary of the Invention [Problem to be solved by the invention]

[0007] When both the diaphragm member 34 and the valve seat 101 are made of metal, the contact of the diaphragm member 34 with the valve seat 33 is metal-to-metal contact, which is likely to cause wear. In particular, a fluid control valve used in ALD needs to repeat contact and separation operations very frequently, and therefore the fluid control valve 100 may need to be replaced with a new one within a few months of starting to be used.

[0008] In order to prevent wear caused by contact between metals, it is conceivable to form the valve seat 101 from fluororesin, which has excellent chemical resistance. However, since the deflection temperature under load of fluororesin at 1.82 MPa measured in accordance with ASTM D-648 is about 50 degrees, the valve seat 101 is easily deformed under high temperature conditions where the temperature of the process gas is 250°C or higher. Therefore, when the diaphragm member 34 repeatedly comes into contact with and separates from the valve seat 101 made of fluororesin under high temperature conditions, the valve seat 101 may be crushed by the diaphragm member 34 beyond the designed value, as shown in FIG. 7, for example, and the dimension in the direction of contact and separation (valve seat height dimension) may be reduced. When the valve seat 101 is crushed excessively in this way, the surface pressure when the diaphragm member 34 comes into contact decreases, which causes 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 amount) until the diaphragm member 34 abuts against the valve seat 101 when the fluid control valve 100 is changed from the valve open state to the valve closed state becomes larger than the design value. If the amount of deformation of the diaphragm member 34 becomes larger than the design value, there is a concern that the diaphragm member 34 will be more susceptible to fatigue failure.

[0009] The present invention has been made in consideration of the above problems, and has an object to provide a fluid control valve that is capable of preventing 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] In order to solve the above problems, a fluid control valve according to 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, characterized in that the valve seat comprises a first annular valve seat made of a fluororesin and a second annular valve seat made of a heat-resistant resin, which are coaxially adjacent to each other, and the heat-resistant resin has a higher deflection temperature under load at 1.82 MPa, measured in accordance with ASTM D-648, than the fluororesin.

[0012] According to the fluid control valve described in (1) above, the sealing performance when the valve is closed is ensured mainly by the first annular valve seat made of fluororesin. This is because the first annular valve seat is made of fluororesin and therefore easily conforms to the shape of the diaphragm member when the diaphragm member abuts against it, and has good transferability. The second annular valve seat is made of a heat-resistant resin having a higher deflection temperature under load than fluororesin, and is less likely to deform than fluororesin even under high temperature conditions. Thus, the second annular valve seat mainly plays a 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 the expansion of the deformation amount (stroke amount) of the diaphragm member until it abuts against the annular valve seat due to the crushing of the valve seat, and thus prevents the deterioration of the sealing performance of the fluid control valve and the occurrence of fatigue failure in the diaphragm member. Examples of fluororesins include perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), and perfluoroelastomer (FFKM).

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

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

[0015] According to the fluid control valve described in (2) or (3) above, the second annular valve seat can be prevented from being deformed even under high temperature conditions in which the temperature of the process gas is 250° C. or higher. Therefore, the second annular valve seat can reliably bear the load applied from the diaphragm member, and the first annular valve seat can be reliably prevented from being excessively crushed. Effect of the Invention

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

[0017] [Figure 1] 1 is a cross-sectional view of a fluid control valve according to an embodiment of the present invention, showing the fluid control valve in an open state. [Diagram 2] FIG. 2 is a partially enlarged view of a portion A in FIG. [Diagram 3] 1 is a cross-sectional view of a fluid control valve according to an embodiment of the present invention, showing a valve closed state of the fluid control valve; [Figure 4] FIG. 4 is a partially enlarged view of a portion B in FIG. [Diagram 5] FIG. 1 is a cross-sectional view of a conventional fluid control valve, showing the fluid control valve in an open state. [Figure 6] FIG. 1 is a cross-sectional view of a conventional fluid control valve, showing the fluid control valve in a closed state. [Figure 7] FIG. 7 is a partially enlarged view of a portion C in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluid control valve according to an embodiment of the present invention will now be described in detail with reference to the drawings. Note that the drawings used in the description are simplified for the purpose of explanation and do not accurately represent the shape, dimensions, etc.

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

[0020] The fluid control valve 1 is a gas valve disposed in a gas supply system of a semiconductor manufacturing device, and is used to control the supply of high-temperature (e.g., about 250°C) process gas. 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. Furthermore, 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) that is loaded inside the case 41, and a columnar drive shaft 42 that is connected to the piston. The actuator unit 4 further includes a pilot port 44 for inputting operating air into the case 41 at the end of the case 41 opposite the spring unit 5 (the upper end in FIG. 1).

[0022] The piston is allowed to slide up and down within the case 41 by supplying or stopping the supply of operating air from the pilot port 44 into the case 41. The drive shaft 62 advances and retreats along its axial direction in accordance with the up and down movement of the piston. The axial direction of the drive shaft 62 is parallel to the up and down direction in Fig. 1 and coincides with the direction in which a diaphragm member 34, described later, moves toward and away from the valve seat 33. The upper side in the figure is the moving away direction, and the lower side is the moving toward and away from the valve seat 33.

[0023] An end of the drive shaft 42 on the valve section 3 side (the lower end in FIG. 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 inside the spring section 5. As a result, as the drive shaft 42 advances and retreats, the first stem 43 also advances and retreats in the same direction. The first stem 43 abuts against a second stem 32, which will be described later, at an end face opposite the drive shaft 42 side. As a result, when the first stem 43 is driven in the abutment direction, the first stem 43 presses the second stem 32 in the abutment direction.

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

[0025] Next, the valve portion 3 will be described. The valve portion 3 includes 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 includes a cylindrical portion 315 that connects to the spring portion 5. Furthermore, a valve chamber 311 is formed inside the cylindrical portion 315 of the body 31.

[0026] A valve port 312 for inputting a process gas into the valve chamber 311 is provided at the center of the bottom of the valve chamber 311. A circular valve seat 33 is fixed to the bottom of the valve chamber 311 on the outer circumferential side of the valve port 312 and coaxially with the valve port 312. The valve chamber 311 communicates with an output flow passage 314 on the radially outer side of the valve seat 33. The output flow passage 314 is used to output the 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 toward the diaphragm member 34. The second stem 32 is held by a holder 35 with the spherical surface 321 in contact with the diaphragm member 34 and so as to be movable 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 crown shape that bulges toward the second stem 32. Therefore, the facing surface 341 of the diaphragm member 34 facing the second stem 32 is a spherical surface. The surface of the diaphragm member 34 opposite the facing surface 341 is a back surface 342. The diaphragm member 34 is provided with a flat edge portion 344 on the outer periphery that is perpendicular to the direction of contact and separation. The edge portion 344 is sandwiched between the holder 35 and the body 31, so that the diaphragm member 34 is fixed to the valve chamber 311. When the diaphragm member 34 is pressed by the second stem 32, the central portion of the diaphragm member 34 is elastically deformed in the contact direction along the spherical surface 321 of the second stem 32. When the pressure from the second stem 32 is released, the diaphragm member 34 returns to its original spherical crown shape by a self-restoring force.

[0029] The valve seat 33 is composed of a first annular valve seat 331 made of a fluororesin and a second annular valve seat 332 made of a heat-resistant resin. Examples of the fluororesin forming the first annular valve seat 331 include perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), and perfluoroelastomer (FFKM). The heat-resistant resin forming the second annular valve seat 332 is preferably one whose deflection temperature under load (hereinafter simply referred to as "deflection temperature under load") at 1.82 MPa measured in accordance with ASTM D-648 is higher than the deflection temperature under load of the above-mentioned fluororesin, which is about 50-55°C, and more preferably has a deflection temperature under load of 125°C or higher. Specific examples of the heat-resistant resin include polyetheretherketone (PEEK), polyetherketone (PEK), polybenzimidazole (PBI), polyimide (PI), and high heat-resistant polyamide (PA). The deflection temperature under load of PEEK is 155°C, that of PEK is 180°C, that of PBI is 410°C, that of PI is 360°C, and that of 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 adjacently positioned on the same axis. More specifically, the first annular valve seat 331 is positioned on the outer periphery side, and the second annular valve seat 332 is positioned on the inner periphery side, with the inner periphery surface of the first annular valve seat 331 and the outer periphery surface of the second annular valve seat 332 being in contact with each other. A crimping portion 316 provided on the body 31 presses the first annular valve seat 331 from the outer periphery 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] In addition, since the first annular valve seat 331 and the second annular valve seat 332 are positioned adjacent to each other on the same axis, an upper end surface 331a of the first annular valve seat 331 facing the diaphragm member 34 and an upper end surface 332a of the second annular valve seat 332 facing the diaphragm member 34 form an abutment surface 33a of the valve seat 33 with which the diaphragm member 34 abuts and separates. Therefore, when the diaphragm member 34 abuts against the valve seat 33, the load applied to the valve seat 33 can be borne 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 located on the outer periphery side, and the second annular valve seat 332 is located on the inner periphery side, but the first annular valve seat 331 may be located on the inner periphery side, and the second annular valve seat 332 may be located on the outer periphery side. In this embodiment, the first annular valve seat 331 is located on the outer periphery side, and the second annular valve seat 332 is located on the inner periphery side in order to reliably fix the valve seat 33. To explain in detail, since the crimping portion 316 is located on the outer periphery side of the valve seat 33, when the crimping portion 316 presses the valve seat 33, the crimping portion 316 is more likely to bite into the valve seat 33 when the first annular valve seat 331, which has a lower hardness, is located on the outer periphery side, and the valve seat 33 is more reliably fixed.

[0033] (Operation of the fluid control valve) Next, the operation of the fluid control valve 1 will be described.

[0034] When the operating air is fed from the pilot port 44 to the actuator unit 4, the piston in the case 41 moves in the separating direction. Accordingly, 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 pressed 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 is in the valve open state as shown in FIG. 1. In this valve open state, the 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 first stem 43 is driven in the abutment direction by the elastic force of the compression coil spring 52. The first stem 43 presses the second stem 32 to move it in the same direction. As the second stem 32 moves, the diaphragm member 34 abuts against the valve seat 33, and the fluid control valve 1 is in the valve closed state, as shown in Fig. 3. In the valve closed state, the flow of process gas from the valve port 312 to the valve chamber 311 is blocked.

[0036] (About the action and effect) As described above, the fluid control valve 1 according to this embodiment has the following features: (1) A fluid control valve 1 including a pressing member (e.g., a second stem 32), a diaphragm member 34, and a valve seat 33, in which 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 includes a first annular valve seat 331 made of a fluororesin and a second annular valve seat 332 made of a heat-resistant resin, which are coaxially adjacent to each other, and 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.

[0037] According to the fluid control valve 1 described in (1) above, the sealing performance when the valve is closed is ensured mainly by the first annular valve seat 331 made of fluororesin. This is because the first annular valve seat 331 is made of fluororesin and therefore easily conforms to the shape of the diaphragm member 34 when the diaphragm member 34 abuts against it, and has good transferability. The second annular valve seat 332 is made of a heat-resistant resin having a higher deflection temperature under load than fluororesin, and is therefore less likely to deform than fluororesin even under high temperature conditions. Therefore, the second annular valve seat 332 mainly plays a role of receiving the load applied from the diaphragm member 34. By the second annular valve seat 332 receiving 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-mentioned abutment and separation operations are repeated.

[0038] Furthermore, the fluid control valve 1 may be annealed in a valve-closed state before use. This annealing process allows the contact surface 33a to conform to the rear surface 342 of the diaphragm member 34 in the valve-closed state. Even when this annealing process is performed, 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 first annular valve seat 331 as well as the second annular valve seat 332 made of a heat-resistant resin, so that the first annular valve seat 331 can be prevented 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 amount) until the diaphragm member abuts against the annular valve seat due to the collapse of the valve seat, and ultimately to prevent a deterioration 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 deflection temperature under load of 1.82 MPa, measured in accordance with ASTM D-648, of 125° C. or higher.

[0041] (3) In the fluid control valve 1 described in (1) or (2), it is preferable that the heat-resistant resin is any one of polyetheretherketone (PEEK), polyetherketone (PEK), polybenzimidazole (PBI), polyimide (PI), and 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 in which the temperature of the process gas is 250° C. or higher. Therefore, the second annular valve seat 332 can reliably receive 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 embodiment is merely an example and does not limit the present invention in any way. Therefore, the present invention can be improved and modified in various ways without departing from the scope of the present invention. For example, in the fluid control valve 1 according to the present embodiment, a pneumatically driven air cylinder is used as the drive unit 2, but other drive sources such as a direct acting servo motor may be used. [Explanation of symbols]

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

Claims

1. The valve includes a pressing member, a diaphragm member, and a valve seat. In the fluid control valve, 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 a fluororesin and a second annular valve seat made of a heat-resistant resin, the first annular valve seat and the second annular valve seat being positioned adjacent to each other on the same axis; The heat-resistant resin has a deflection temperature under load of 1.82 MPa, as measured in accordance with ASTM D-648, that is higher than that of the fluororesin; A fluid control valve comprising:

2. 2. The fluid control valve according to claim 1, The heat-resistant resin has a deflection temperature under load of 1.82 MPa, as measured in accordance with ASTM D-648, of 125° C. or higher; A fluid control valve comprising:

3. 3. The fluid control valve according to claim 1, The heat-resistant resin is any one of polyether ether ketone, polyether ketone, polybenzimidazole, polyimide, and high heat-resistant polyamide; A fluid control valve comprising:

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