Fluid control valve

Abstract

Provided is a fluid control valve in which deformation of an annular valve seat is suppressed even under high-temperature conditions, thereby preventing deterioration of sealing performance and fatigue failure of a diaphragm member. This fluid control valve (1) is provided with a pressing member (for example, a second valve rod (32)), a diaphragm member (34), and a valve seat (33), and the pressing member (second valve rod (32)) presses and deforms the diaphragm member (34), thereby bringing the diaphragm member (34) into contact with the valve seat (33). The valve seat (33) is provided with a first annular valve seat (331) comprising a fluororesin and a second annular valve seat (332) comprising a heat-resistant resin, which are positioned coaxially so as to be adjacent to each other. The heat-resistant resin has a higher load deflection temperature at 1.82 MPa as measured in accordance with ASTM D-648 than the fluororesin.

Description

Technical Field

[0001] The present invention relates to a fluid control valve including a pressing member, a diaphragm member and a valve seat. The pressing member presses the diaphragm member to deform the diaphragm member, thereby causing the diaphragm member to abut against the valve seat. Background Art

[0002] A variety of process gases are used in film forming processes in semiconductor manufacturing processes. In order to control the flow rate of the process gases, a fluid control valve is used. As a 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 a pneumatic on-off valve that controls the flow rate of the process gas by making a diaphragm member contact and separate from a valve seat.

[0003] use Figure 5-Figure 7 Let's explain it in more detail. Figure 5 It is a cross-sectional view of a fluid control valve 100 in the prior art, showing the open valve state of the fluid control valve 100 . Figure 6 It is a cross-sectional view of a fluid control valve 100 in the prior art, showing a closed valve state of the fluid control valve 100 . Figure 7 for Figure 6 A partial enlarged view of part C.

[0004] like Figure 5 As shown in FIG. 1 , the apex of the spherical diaphragm member 34 of the fluid control valve 100 abuts against the valve stem 32. Then, by the action of the actuator part 4 (e.g., cylinder) or the force of the compression coil spring 52 in the spring part 5, the valve stem 32 presses the diaphragm member 34 downward in the figure to deform it and abut against the annular valve seat 101. Figure 6 As shown in FIG. 1 , the state in which the diaphragm member 34 abuts against the valve seat 101 is the closed valve state of the fluid control valve 100. Then, when the pressure of the valve stem 32 on the diaphragm member 34 is released, the diaphragm member 34 returns to its original spherical crown shape under its self-restoring force and leaves the valve seat 101. Figure 5 As shown, the state in which the diaphragm member 34 is away from the valve seat 101 is the valve-open state of the fluid control valve 100 .

[0005] The process gas used in atomic layer deposition (ALD), a film forming technology that has become popular in recent years, may be high in temperature 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 literature] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2016-180490 [Patent Document 2] Japanese Patent Application Publication No. 2017-223318 Summary of the invention [Problems to be solved by the invention]

[0007] When the diaphragm member 34 and the valve seat 101 are both made of metal, the contact between the diaphragm member 34 and the valve seat 101 is metal-to-metal contact, which is prone to wear. In particular, the fluid control valve used in ALD must repeat the contact and separation actions at a very high frequency, so the fluid control valve 100 may need to be replaced with a new one within a few months from the start of use.

[0008] In order to prevent wear caused by contact between metals, it is considered to form the valve seat 101 with fluororesin having excellent chemical resistance. However, the load deflection temperature of fluororesin at 1.82 MPa measured according to ASTM D-648 is about 50 degrees, so the valve seat 101 is easily deformed under high temperature conditions such as the process gas temperature of 250°C or more. Therefore, when the diaphragm member 34 repeatedly contacts and separates from the fluororesin valve seat 101 under high temperature conditions, the valve seat 101, for example, Figure 7 As shown in the figure, the diaphragm member 34 is flattened to a degree exceeding the design value, so that there is a risk that the dimension in the abutting and separating direction (valve seat height dimension) is reduced. In this way, when the valve seat 101 is excessively flattened, the contact pressure of the diaphragm member 34 when it is in the abutting state is reduced, so that the sealing performance of the fluid control valve 100 is reduced. In addition, when the height dimension of the valve seat 101 is reduced, the deformation amount (stroke amount) from the diaphragm member 34 abutting the valve seat 101 when the fluid control valve 100 changes from the open valve state to the closed valve state becomes larger than the design value. When the deformation amount of the diaphragm member 34 becomes larger than the design value, there is a risk that the diaphragm member 34 is easily fatigued and broken.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a fluid control valve which can suppress deformation of an annular valve seat even under high temperature conditions, thereby preventing reduction in sealing performance and fatigue failure of a diaphragm member. [Technical means to solve the problem]

[0010] In order to solve the above-mentioned problems, a fluid control valve in one aspect of the present invention has the following structure.

[0011] (1) A fluid control valve comprising a pressing member, a diaphragm member and a valve seat, wherein the pressing member presses the diaphragm member to deform the diaphragm member, thereby causing the diaphragm member to abut against the valve seat, the fluid control valve being characterized in that the valve seat comprises a first annular valve seat made of fluororesin and a second annular valve seat made of heat-resistant resin, which are coaxially located 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.

[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 composed of fluororesin. The reason is that the first annular valve seat is composed of fluororesin, so it is easy to adapt to the shape of the diaphragm member when the diaphragm member is in abutment, and the transferability is good. In addition, the second annular valve seat is composed of a heat-resistant resin with a load deflection temperature higher than that of fluororesin, so it is not easy to deform under high temperature conditions compared to fluororesin. Therefore, the second annular valve seat mainly plays the role of bearing the load applied from the diaphragm member. The second annular valve seat bears the load applied from the diaphragm member at a position adjacent to the first annular valve seat, thereby preventing the first annular valve seat from being excessively flattened by the load. As a result, it is possible to prevent the expansion of the deformation amount (stroke amount) of the diaphragm member from abutting against the annular valve seat due to the collapse of the valve seat, thereby preventing the sealing performance of the fluid control valve from being reduced and the diaphragm member from being fatigued. In addition, examples of the fluororesin include perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), and perfluoroelastomer (FFKM).

[0013] (2) The fluid control valve according to (1), wherein the heat-resistant resin preferably has a deflection temperature under load at 1.82 MPa measured in accordance with ASTM D-648 of 125° C. or higher.

[0014] (3) The fluid control valve according to (1) or (2), wherein the heat-resistant resin is preferably 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, deformation of the second annular valve seat can be prevented even under high temperature conditions such as a process gas temperature of 250° C. or higher. Therefore, the second annular valve seat can reliably bear the load applied from the diaphragm member, thereby reliably preventing the first annular valve seat from being excessively flattened. [Effects of the Invention]

[0016] According to the fluid control valve of the present invention, deformation of the valve seat is suppressed even under high temperature conditions, thereby preventing reduction in sealing performance and fatigue failure of the diaphragm member. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Embodiments of the fluid control valve of the present invention will be described in detail with reference to the accompanying drawings. Note that the drawings used in the description are simplified for the purpose of description and do not accurately represent shapes and dimensions.

[0019] (About the structure 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. Figure 1 This is a cross-sectional view of the fluid control valve 1 according to the present embodiment, showing the open state of the fluid control valve 1 . Figure 2 for Figure 1 A partial enlarged view of part A. Figure 3 This is a cross-sectional view of the fluid control valve 1 according to the present embodiment, and shows the closed valve state of the fluid control valve 1 . Figure 4 for Figure 3 A partial enlarged view of part B.

[0020] The fluid control valve 1 is a gas valve provided in the 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 pneumatic on-off valve, such as Figure 1 As shown in FIG. 1 , the valve body 1 includes a driving unit 2 and a valve unit 3 . The driving unit 2 further includes an actuator unit 4 and a spring unit 5 .

[0021] First, the actuator unit 4 is described. The actuator unit 4 is an air cylinder driven by air pressure. The actuator unit 4 includes a cylindrical housing 41, a piston (not shown) loaded inside the housing 41, and a cylindrical drive shaft 42 combined with the piston. Furthermore, the actuator unit 4 is provided at an end ( Figure 1 The upper end portion in the housing 41 is provided with a pressure guide port 44 for inputting operating air into the housing 41.

[0022] The piston can slide in the up-down direction in the housing 41 by supplying or stopping the operating air from the pressure guide port 44 into the housing 41. Then, the drive shaft 42 moves forward and backward in the axial direction of the drive shaft 42 as the piston moves up and down. The axial direction of the drive shaft 42 is parallel to the Figure 1 The direction parallel to the up-down direction in FIG. 3 is consistent with the direction in which the diaphragm member 34 described later abuts and separates from the valve seat 33. In the present embodiment, the direction toward the upper side in the figure is the separation direction, and the direction toward the lower side is the abutment direction.

[0023] The end portion of the drive shaft 42 on the valve portion 3 side ( Figure 1 The first valve stem 43 is provided at the top end of the drive shaft 42 in the spring portion 5. Therefore, as the drive shaft 42 advances and retreats, the first valve stem 43 also advances and retreats in the same direction. The first valve stem 43 abuts against the second valve stem 32 described later at the end surface on the side opposite to the drive shaft 42. Thus, when the first valve stem 43 is driven in the abutting direction, the first valve stem 43 presses the second valve stem 32 in the abutting direction.

[0024] Next, the spring portion 5 will be described. The spring portion 5 is provided with a compression coil spring 52 coaxially located with the drive shaft 42 in the internal space 51. The compression coil spring 52 is compressed between the end surface 53 on the actuator portion 4 side of the internal space 51 and the first valve stem 43. Therefore, the compression coil spring 52 always applies force to the first valve stem 43 in the abutting direction (downward direction in the figure).

[0025] Next, the valve portion 3 is described. The valve portion 3 includes a valve body 31, a second valve stem 32 (an example of a pressing member), a valve seat 33, and a diaphragm member 34. The valve body 31 includes a cylindrical portion 315 connected to the spring portion 5. In addition, a valve chamber 311 is formed inside the cylindrical portion 315 in the valve 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. In addition, a circular valve seat 33 is fixed to the bottom surface of the valve chamber 311 on the outer peripheral side of the valve port 312 and in a manner coaxial with the valve port 312. Furthermore, the valve chamber 311 is connected to an output flow path 314 on the radial outer side of the valve seat 33. The output flow path 314 is used to output the process gas from the valve chamber 311.

[0027] The second valve stem 32 is made of, for example, stainless steel. The second valve 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 valve stem 32 is held by the valve frame 35 in a state where the spherical surface 321 abuts against the diaphragm member 34 and is movable up and down.

[0028] The diaphragm member 34 is made of, for example, Ni alloy. In addition, the diaphragm member 34 is formed into a spherical crown shape that bulges toward the second valve stem 32 side. Therefore, the facing surface 341 of the diaphragm member 34 that faces the second valve stem 32 is a spherical surface. Furthermore, the surface on the opposite side of the facing surface 341 of the diaphragm member 34 is set as the back surface 342. In addition, the diaphragm member 34 has a planar edge 344 at the outer periphery that is orthogonal to the direction of abutment and separation. The edge 344 is clamped by the valve frame 35 and the valve body 31, whereby the diaphragm member 34 is fixed in the valve chamber 311. By fixing it in this way, when the diaphragm member 34 is pressed by the second valve stem 32, the central portion is elastically deformed in the abutment direction along the spherical surface 321 of the second valve stem 32 (refer to Figure 3 , Figure 4 ). Then, when the pressure exerted by the second valve stem 32 is released, the diaphragm member 34 returns to its original spherical crown shape under the self-restoring force (refer to Figure 1 , Figure 2 ).

[0029] The valve seat 33 is composed of a first annular valve seat 331 and a second annular valve seat 332. The first annular valve seat 331 is composed of a fluororesin, and the second annular valve seat 332 is composed 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 preferably has a load deflection temperature under 1.82 MPa measured according to ASTM D-648 (hereinafter referred to as "load deflection temperature") that is about 50 to 55°C higher than the load deflection temperature of the fluororesin, and more preferably has a load deflection temperature of 125°C or more. Specifically, examples include polyetheretherketone (PEEK), polyetherketone (PEK), polybenzimidazole (PBI), polyimide (PI), and high heat-resistant polyamide (PA). Furthermore, the deflection temperature under load of PEEK is 155°C, the deflection temperature under load of PEK is 180°C, the deflection temperature under load of PBI is 410°C, the deflection temperature under load of PI is 360°C, and the deflection temperature under load 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 located on the same axis in an adjacent manner. More specifically, the first annular valve seat 331 is located on the outer peripheral side, and the second annular valve seat 332 is located on the inner peripheral side, and is placed in a state where the inner peripheral surface of the first annular valve seat 331 and the outer peripheral surface of the second annular valve seat 332 are in contact with each other. In addition, the pressing portion 316 provided on the valve body 31 presses the first annular valve seat 331 from the outer peripheral side, thereby the first annular valve seat 331 and the second annular valve seat 332 are fixed 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 coaxially located adjacent to each other, 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 constitute the abutting surface 33a of the valve seat 33 for the diaphragm member 34 to abut and separate from. 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] Furthermore, although 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 in the present embodiment, the first annular valve seat 331 may be located on the inner circumference side and the second annular valve seat 332 may be located on the outer circumference side. In the present embodiment, 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 for the purpose of reliably fixing the valve seat 33. Specifically, since the pressing portion 316 is located on the outer circumference side of the valve seat 33, when the pressing portion 316 is used to press the valve seat 33, the first annular valve seat 331 having a lower hardness is located on the outer circumference side, which makes it easier for the pressing portion 316 to squeeze into the valve seat 33, and the fixing of the valve seat 33 becomes reliable.

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

[0034] When the operating air is delivered from the pressure guide port 44 to the actuator unit 4, the piston in the housing 41 moves in the direction of separation. Along with this, the drive shaft 42 is driven in the same direction. The first valve stem 43 is connected to the drive shaft 42, so it rises against the elastic force of the compression coil spring 52. As a result, the second valve stem 32, which was originally pressed by the first valve stem 43, rises under the restoring force of the diaphragm member 34. The diaphragm member 34 leaves the valve seat 33, and the fluid control valve 1 is like Figure 1 In this valve open state, the process gas flows into the valve chamber 311 from the valve port 312 and is then output to the output flow path 314 .

[0035] On the other hand, when the supply of operating air to the pressure guide port 44 is stopped, the first valve stem 43 is driven in the abutting direction due to the elastic force of the compression coil spring 52. The first valve stem 43 presses the second valve stem 32, thereby causing the second valve stem 32 to move in the same direction. As the second valve stem 32 moves, the diaphragm member 34 abuts against the valve seat 33, and the fluid control valve 1 is moved like Figure 3 In the valve closed state, the flow of the process gas from the valve port 312 to the valve chamber 311 is blocked.

[0036] (About the effect) (1) As described above, the fluid control valve 1 of the present embodiment is configured as follows, that is, it includes a pressing member (for example, a second valve stem 32), a diaphragm member 34 and a valve seat 33, the pressing member (second valve stem 32) presses the diaphragm member 34 to deform it, thereby causing it to abut against the valve seat 33, and the valve seat 33 includes a first annular valve seat 331 made of fluororesin and a second annular valve seat 332 made of heat-resistant resin located coaxially in an adjacent manner, and the heat-resistant resin has a load deflection temperature under 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 composed of fluororesin. The reason is that the first annular valve seat 331 is composed of fluororesin, so it is easy to adapt to the shape of the diaphragm member 34 when the diaphragm member 34 is in abutment, and the transferability is good. In addition, the second annular valve seat 332 is composed of a heat-resistant resin with a load deflection temperature higher than that of fluororesin, so it is not easy to deform under high temperature conditions compared to fluororesin. Therefore, the second annular valve seat 332 mainly plays the role of bearing the load applied from the diaphragm member 34. The second annular valve seat 332 bears the load applied from the diaphragm member 34 at a position adjacent to the first annular valve seat 331, thereby preventing the first annular valve seat 331 from being excessively flattened by the load applied from the diaphragm member 34 even if the above-mentioned abutment and separation actions are repeated.

[0038] In addition, the fluid control valve 1 may be subjected to an annealing treatment in the valve-closed state before use. Through the annealing treatment, the contact surface 33a is adapted to the back surface 342 of the diaphragm member 34 in the valve-closed state. During the annealing treatment, while the diaphragm member 34 is in contact with the valve seat 33, the second annular valve seat 332 made of heat-resistant resin also receives the load applied to the valve seat 33 together with the first annular valve seat 331, so that the first annular valve seat 331 can be prevented from being excessively crushed.

[0039] As described above, by preventing the valve seat 33 (first annular valve seat 331) from collapsing, it is possible to prevent the expansion of the deformation (stroke) of the diaphragm member 34 until it abuts against the annular valve seat caused by the collapse of the valve seat, thereby preventing the sealing performance of the fluid control valve 1 from being reduced and the diaphragm member 34 from being fatigued.

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

[0041] (3) In the fluid control valve 1 according to (1) or (2), the heat-resistant resin is preferably 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 such as a process gas temperature of 250° C. or higher. Therefore, the second annular valve seat 332 can reliably bear the load applied from the diaphragm member 34, thereby reliably preventing the first annular valve seat 331 from being excessively flattened.

[0043] Furthermore, the above-mentioned embodiments are merely examples and do not limit the present invention in any way. Therefore, the present invention can be modified and deformed in various ways without departing from the main purpose. For example, in the fluid control valve 1 of this embodiment, an air cylinder driven by air pressure is used as the driving part 2, but other driving sources, such as a direct-acting servo motor, etc., can also be used. Explanation of symbols

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

Claims

1. A fluid control valve comprising a pressing member, a diaphragm member and a valve seat, The pressing member presses the diaphragm member to deform it, thereby causing it to abut against the valve seat. The fluid control valve is characterized in that: The valve seat includes a first annular valve seat made of fluororesin and a second annular valve seat made of heat-resistant resin, which are coaxially adjacent to each other. 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.

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

3. The fluid control valve according to claim 1 or 2, characterized in that: The heat-resistant resin is any one of polyetheretherketone, polyetherketone, polybenzimidazole, polyimide, and high heat-resistant polyamide.

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