Fluid control valve

Abstract

This integrated, compact fluid control valve can handle different fluid pressures, allowing for high-precision fluid control by rapidly opening and closing the valve body when handling low-pressure fluids, and providing strong sealing force when closed to reliably prevent leakage when handling high-pressure fluids. It also maintains a stable Cv value, preventing changes in flow rate while suppressing a decrease in sealing performance and improving durability, and reduces the consumption of compressed air for operation. [Solution] Each divided piston 23 is arranged in series with respect to the valve seat 13 in an elastic state through a plurality of springs 24 with different spring loads, and an air inlet 25 is formed in the actuator 11, and each piston moves up and down individually and independently within the actuator by compressed air from each air inlet or the elastic force of each spring, and the valve body is provided so as to be able to seal the flow path with different sealing forces according to the downward state of each piston.

Description

Technical Field

[0001] The present invention relates to a fluid control valve, and more particularly to a fluid control valve provided with an air-driven actuator that operates a piston by air pressure to drive a valve body to open and close.

Background Art

[0002] Conventionally, this type of air-driven fluid control valve is used, for example, in semiconductor manufacturing processes and panel manufacturing processes, and is usually provided as an integrated type equipped with an actuator for driving the valve body. In such a fluid control valve, there is a structure in which a piston-driven drive mechanism for driving the valve body with compressed air is provided inside the actuator, and a spring for driving the piston is further attached to this drive mechanism. With this internal structure, the piston is driven by the elastic force of the spring in a direction opposite to the driving direction of the piston by the pressure fluid, and the valve body is opened and closed.

[0003] As an air-driven valve having such a structure, for example, the fluid control valve of Patent Document 1 is disclosed. This fluid control valve is equipped with an actuator that is normally in a valve-closed state, which is called a so-called normally closed type, and a piston mounted inside the actuator is mounted in a cylinder via the elastic force of a spring.

[0004] In particular, in this fluid control valve, large and small piston chambers with different inner diameters are partitioned by a partition wall, and large-diameter pistons and small-diameter pistons are attached to these large and small piston chambers via a plurality of springs. Normally, due to the elastic force of the spring, the valve body is urged in the valve-closed direction from the large-diameter piston and the small-diameter piston through a valve rod. Thus, by sucking and exhausting pressure fluid into the cylinder where each piston is mounted from two ports, each piston is driven, or these two pistons are driven simultaneously, and a driving force is transmitted from a single valve rod to the valve body against the elastic biasing force of the spring, and the driving force of the valve rod in the valve-opening direction is controlled over a wide range to perform an opening and closing operation on the valve body side.

[0005] Incidentally, such fluid control valves are sometimes used to supply material gases (process gases) for semiconductor manufacturing processes to process chambers. Among these, some are designed to be used for supplying material gases to process chambers in response to ALD (Atomic Layer Deposition) and ALE (Atomic Layer Etching), which are said to be the mainstream manufacturing processes for next-generation semiconductors. In particular, they are sometimes used during the process of supplying material gases to the process chamber, as well as during purging of fluid control valves and piping, or during maintenance such as airtightness testing.

[0006] In this case, since the process time is determined by the opening and closing speed of the valve body, a faster opening and closing speed of the valve body is required. Furthermore, as the number of times the valve body opens and closes per unit time increases, improved durability is required for the valve body and valve seat. In addition, it is desirable to supply the material gas in a state where the supply rate is stable while suppressing changes in the Cv value during the valve opening state in the process. Thus, in processes requiring high precision, such as ALD and ALE, ensuring functionality, including valve opening and closing speed, durability, and stability of Cv values, is particularly important. On the other hand, when the valve is closed during the process, even when the material gas attempts to flow at its operating pressure, the spring's elastic force must reliably operate the valve body to the closed position to ensure a seal.

[0007] As described above, different functionalities are required during the process compared to purging or maintenance. For this reason, instead of using an integrated fluid control valve, the fluid circuit 1 shown in Figure 5 may be used for processing, purging, or maintenance to accommodate ALD and ALE processes. In Figure 5, two valves, control valve 3 and control valve 4, are provided on the primary side of the process chamber 2. Control valve 3 is a valve that opens and closes during the process described above, and has a small flow rate when the valve is open and a small stroke when the valve body, which is made of a diaphragm, is opened and closed. On the other hand, control valve 4 has a larger flow rate when the valve is open and a larger stroke when the valve body is opened and closed than control valve 3. On the primary side of these control valves 3 and 4, a process-side passage 5 for supplying material gas during the process and a supply passage 6 for supplying pressure gas during purging or maintenance are connected in parallel, and these process-side passage 5 and supply passage 6 are provided with on-off valves 7 and 8 for opening and closing the passages, respectively.

[0008] In the fluid circuit 1 described above, during the process, the on-off valve 7 of the process-side flow path 5 is set to open, and the on-off valve 8 of the supply flow path 6 is set to close, allowing material gas to be supplied from the process-side flow path 5. While keeping the control valve 4 in the open position, the control valve 3 is opened and closed, thereby supplying or stopping a predetermined small flow rate of material gas, and controlling the flow rate of the material gas.

[0009] On the other hand, during purging or maintenance, by opening the on-off valve 8 of the supply passage 6 and closing the on-off valve 7 of the process-side passage 5, allowing pressurized gas to be supplied from the supply passage 6, and by keeping the control valve 3 open while operating the control valve 4 to open and close, it becomes possible to supply or stop the supply of pressurized gas at a larger flow rate than during process operation, thereby enabling purging or maintenance. As shown above, in the fluid circuit 1 of Figure 5, two valves, control valve 3 and control valve 4, and in addition to these control valves 3 and 4, two more on-off valves 7 and 8 for opening and closing the flow path are used to control the fluid during process, purging, or maintenance.

[0010] In this case, when supplying material gas to process chamber 2, material gas using materials with low vapor pressure, such as solid materials, is often supplied. At this time, the pressure generated inside the valve is relatively low, for example, 0.1 MPaG or less. On the other hand, when purging or maintaining the piping, the pressure of the pressurized gas is often supplied at a higher pressure than the material gas used during the process. At this time, the maximum operating pressure generated inside the valve is for example, 0.2 MPaG, and in some cases, 0.7 MPaG or higher. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2002-349747 [Overview of the project] [Problems that the invention aims to solve]

[0012] When using the aforementioned integrated fluid control valve for fluid control in a process chamber while also supporting ALD and ALE, the actuator must be designed to seal the maximum operating pressure of the pressurized gas during purging or maintenance. In this case, in a normally closed type fluid control valve, in order to increase the maximum operating pressure when the valve is closed, it is necessary to increase the elastic force of the spring that seals the valve body to increase the sealing force.

[0013] However, increasing the spring's elastic force increases the load (pressure) on the valve body and valve seat, which in turn increases the force required to move the valve body in the opening direction. This increases the load on the compressed air, increases the actuator's thrust, and slows down the piston's movement speed in the valve opening direction. In this case, the valve may not be suitable for use in ALD or ALE processes that require high-speed valve movement.

[0014] In addition, when the spring's elastic force increases, repeated opening and closing of the valve body makes it easier for surface roughness and deformation to occur on the valve body and valve seat. Moreover, in valves used in semiconductor manufacturing, the valve seat is often made of resin materials such as PFA or other fluororesins that have excellent heat and chemical resistance. In this case, because the hardness is lower compared to metal valve seats, it is more prone to deformation and breakage. Deformation or breakage of the valve seat increases the stress on the diaphragm on the valve body side, leading to a decrease in durability.

[0015] If the valve seat is deformed or damaged, the gap between them increases when the valve is open. This gap can lead to problems such as reduced sealing performance when the valve is closed, or changes in the Cv value when the valve is open, resulting in decreased flow rate stability. Thus, increasing the spring's elastic force to seal the maximum operating pressure of the pressurized gas during purging or maintenance will reduce the valve's opening and closing speed, as well as the sealing performance and durability of the valve body and valve seat during the process, and will also worsen the stability of the Cv value. Furthermore, in order to reliably open the valve in response to the spring force required for closing the valve, it is necessary to increase the volume inside the cylinder and increase the amount of compressed air used.

[0016] On the other hand, the fluid control valve described in Patent Document 1 allows for the lifting and lowering of a single valve stem by driving the two pistons individually or simultaneously, thereby widening the range of its driving force (the range of its vertical movement). This enables control over a wide range of flow rates when the valve body is open, and allows for a slightly open valve body by supplying pressurized fluid to only one piston, or a large flow rate when the valve is fully open by supplying pressurized fluid to both pistons.

[0017] However, because this valve has a structure in which a coil spring acting elastically in the fully closing direction acts on a single valve stem, when fully closed, the combined force of the elastic biasing forces of multiple coil springs is applied to the valve seat side. As described above, various problems arise when the valve is closed due to the strong elastic force of the coil springs. For this reason, when this valve is used in ALD or ALE processes, process stability may be reduced.

[0018] On the other hand, if, as shown in Figure 5, two control valves 3 and 4 are used as fluid control valves to perform process, purging, or maintenance, not only will the number of control valves 3 and 4 increase, but two on-off valves 7 and 8 for opening and closing the flow path will also be required, significantly increasing the total number of valves used. In addition, there are problems such as an increase in the process-side flow path 5 and supply flow path 6 for connecting these four valves, and the overall complexity of the fluid circuit 1 in order to control the operation of each valve. Thus, the fluid circuit 1 in Figure 5 is larger than an integrated fluid control valve, making it less compact, and the increased complexity of flow path control also worsens its ability to be integrated into integrated semiconductor manufacturing systems and panel manufacturing systems.

[0019] As described above, there has been a strong demand for the development of a compact fluid control valve that can handle both low-pressure material gas usage during the process and high-pressure gas usage during purging or maintenance, even when the pressure of the fluid flowing through the valve differs, and that operates appropriately in all cases, even when high-precision control such as ALD and ALE is required.

[0020] The present invention has been developed to solve conventional problems, and its object is to be able to open and close a flow path in response to different fluid pressures. When flowing a low-pressure fluid, the valve body is opened and closed at high speed to control the fluid with high precision. When flowing a high-pressure fluid, even when the valve is closed, a high sealing force is exerted to reliably prevent leakage, suppress a decrease in sealing performance, improve durability, and flow the fluid while preventing a change in flow rate with a stable Cv value, and also suppress the consumption of compressed air for driving. It is to provide an integrated and compact fluid control valve that can achieve this.

Means for Solving the Problems

[0021] To achieve the above object, the invention according to claim 1 is a fluid control valve in which a piston is mounted inside an actuator via a spring, and this piston separates and contacts the valve body from the valve seat by compressed air from an air supply port or the elastic force of the spring to open and close the flow path. The piston is formed by being divided into a plurality of parts, and each of these divided pistons is arranged in series with respect to the valve seat in an elastic state through a plurality of springs with different spring loads, and the actuator is provided with air supply ports for supplying compressed air that operates each divided piston in a direction opposite to the elastic direction of each spring. Each divided piston is provided to move up and down individually within the actuator with a predetermined stroke by the compressed air from these air supply ports or the elastic force of each spring. The valve body is a fluid control valve provided so as to be able to seal the flow path with different sealing forces according to the descending states of the plurality of divided pistons.

[0022] The invention according to claim 2 is a fluid control valve in which each divided piston has a first piston arranged on the primary side, which is a position near the valve body, and a second piston provided on the secondary side with respect to the valve body than the first piston. The first piston and the second piston are provided to be able to move up and down simultaneously, or the first piston is provided to be able to move up and down in a state where the second piston has risen.

[0023] The invention according to claim 3 is a fluid control valve in which a first spring is mounted on the first piston side and a second spring is mounted on the second piston side, and the spring load of the second spring is set to be greater than the spring load of the first spring.

[0024] The invention according to claim 4 is a fluid control valve in which the spring load of the first spring is set to a magnitude that seals the material gas for semiconductor manufacturing processes supplied into the flow path when the valve body is pressed against the valve seat through the first piston in a state where the second piston has risen.

[0025] The invention according to claim 5 is a fluid control valve in which the sum of the spring loads of the first spring and the second spring is set to a magnitude that seals the purge or maintenance pressure gas supplied into the flow path when the valve body is pressed against the valve seat through the first piston and the second piston.

[0026] The invention according to claim 6 is a fluid control valve in which each spring is mounted in a resilient state in a direction to lower each divided piston and close the valve body, and each air supply port is formed in an actuator so as to be able to supply compressed air in a direction to raise each divided piston and open the valve body.

[0027] The invention according to claim 7 is a fluid control valve in which a gap is provided between the opposing surfaces of the second piston and the raised first piston when the first piston moves up and down in a state where the second piston has risen.

Effect of the Invention

[0028] According to the invention of claim 1, a piston is formed by dividing it into multiple parts, and each of these divided pistons is arranged in series with respect to the valve seat in an elastic state through multiple springs of different spring loads, and each actuator is formed with an air inlet for supplying compressed air that moves each piston in the opposite direction to the elastic direction of each spring, and each piston moves up and down individually and independently within the actuator by the compressed air from each air inlet or the elastic force of each spring, and the valve body flows through a flow path with different sealing forces depending on the downward state of each piston Since the valve is designed to be sealable, the flow path can be opened and closed in response to different fluid pressures, allowing it to handle both very low-pressure and extremely high-pressure fluids. When flowing low-pressure fluids such as those at an operating pressure of 0.1 MPaG, operating only the split piston on the valve body side allows the valve body to open and close at a higher speed than when all pistons are operated, enabling highly precise fluid control. Even when flowing extremely high-pressure gases such as those at a maximum operating pressure of 0.7 MPaG, the split piston and multiple springs provide a high sealing force when the valve is closed, reliably preventing leakage. Because the thrust of the piston can be reduced, stress on the valve body and valve seat can be suppressed, preventing a decrease in sealing performance and improving durability. By suppressing the deformation of these valve bodies and valve seats, fluid can be flowed with high-precision fluid control while preventing changes in flow rate at a stable Cv value, and the consumption of compressed air for driving can also be reduced. For these reasons, it is particularly suitable for processes that require precise fluid control of minute flow rates by controlling the supply amount of material gas through high-speed opening and closing of valve bodies such as ALD and ALE, and can be installed while contributing to improved cycle time and process stability in manufacturing lines, etc. In this case, even if the material gas is heated to high temperatures, including the piping, by increasing the flow rate or decreasing the vapor pressure of the material gas in each process such as ALD and ALE, the load on the valve seat and valve body is suppressed and thermal resistance is improved. Furthermore, because it is an integrated unit, it can be made compact, making it easy to install in locations with limited footprints in various semiconductor manufacturing processes and panel manufacturing processes.

[0029] According to the invention of claim 2, each divided piston has a first piston and a second piston, and these pistons are provided to be able to move up and down simultaneously. When a fluid with a high maximum operating pressure is flowed inside during purging or maintenance, these two pistons ensure a flow path for the high-pressure fluid when the valve is open, allowing the fluid to flow smoothly, and when the valve is closed, the high thrust generated by the combined force of the two pistons reliably seals the pressurized gas and prevents internal leakage. Furthermore, since the first piston is provided to be able to move up and down with the second piston raised, when a fluid with a low operating pressure is flowed inside, the valve body can be opened and closed at high speed with a smaller stroke than when the first and second pistons are moved up and down simultaneously, enabling high-precision flow rate control of the fluid with a low operating pressure.

[0030] According to the invention of claim 3, since the spring load of the second spring is set to be greater than the spring load of the first spring, when a fluid with a low operating pressure is flowed inside, the load is reduced by the first spring, allowing for a smooth supply of compressed air. As a result, the flow rate of the fluid with a low operating pressure can be controlled with high precision and high speed by opening and closing only the first piston with compressed air.

[0031] According to the invention of claim 4, the spring load of the first spring is set to a size that seals the material gas for the semiconductor manufacturing process supplied into the flow path when the second piston is raised and presses the valve body against the valve seat through the first piston. Therefore, when a material gas with a low operating pressure is flowed inside during processes such as ALD and ALE, this material gas can be flowed into the flow path of the process chamber or the like with high precision flow control.

[0032] According to the invention of claim 5, the sum of the spring loads of the first spring and the second spring is set to a size that seals the pressurized gas supplied into the flow path for purging or maintenance when the valve body is pressed against the valve seat through the first piston and the second piston. Therefore, when purging or maintenance of ALD or ALE, when a high-pressure gas is flowed inside, the valve can be kept open while ensuring a large flow rate, while when the valve is closed, it exhibits high sealing performance to reliably seal the pressurized gas.

[0033] According to the invention of claim 6, each spring is mounted in an elastic state to lower each divided piston and close the valve body, and each air intake port is formed in the actuator so that compressed air can be supplied in the direction that raises each divided piston and opens the valve body. Thus, it can be configured as an integrated valve equipped with a normally closed type actuator, which can maintain a closed valve state under normal conditions and maintain an open valve state by supplying compressed air when fluid control is required.

[0034] According to the invention of claim 7, when the first piston moves up and down while the second piston is raised, a gap is provided between the opposing surfaces of the second piston and the raised first piston. Therefore, when the first piston is raised while the second piston is raised, contact between these opposing surfaces is prevented, thereby preventing the generation of shocks during fluid control and preventing deformation or damage to the first and second pistons. [Brief explanation of the drawing]

[0035] [Figure 1] This is a longitudinal cross-sectional view showing the fully closed state of an embodiment of the fluid control valve according to the present invention. [Figure 2] Figure 1 is a longitudinal cross-sectional view showing the fully open state of the fluid control valve. [Figure 3] This is a cross-sectional view showing the state in which only the first piston has risen from the fluid control valve in Figure 2. [Figure 4] This is a schematic diagram showing the open and closed states of the valve body of a fluid control valve according to an embodiment of the present invention. [Figure 5]This is a schematic diagram showing a fluid control circuit using multiple control valves. [Modes for carrying out the invention]

[0036] Hereinafter, embodiments of the fluid control valve of the present invention will be described in detail with reference to the drawings. Figure 1 shows the fully closed state of the fluid control valve of the present invention, and Figure 2 shows the fully open state of the fluid control valve of Figure 1.

[0037] In this embodiment, the fluid control valve 10 is connected to the primary side of a process chamber (not shown) in a semiconductor manufacturing apparatus and used as a valve corresponding to ALD and ALE. The opening and closing of this fluid control valve 10 controls the pressure fluid flowing inside. The pressure fluid includes a pressure gas for purging or maintenance and a material gas for the semiconductor manufacturing process. The pressure gas is at a higher pressure than the material gas, and high-pressure compressed air is used as this pressure gas. The material gas is flow-controlled through the fluid control valve 10 and is provided so that it can be supplied to the process chamber.

[0038] In Figure 1, the fluid control valve 10 in this embodiment has an actuator 11, a valve body 12 made of a diaphragm, a valve seat 13, and a body 14, and its height (total length) is set to, for example, 5 inches or less.

[0039] First, the actuator 11 in the fluid control valve 10 will be described. The actuator 11 comprises a base 20, a case 21, a cover 22, a piston 23, and a spring 24, and is provided on the upper side of the fluid control valve 10. The actuator 11 is provided with an outer diameter of, for example, φ38 mm or less, and is equipped with an air inlet 25 for supplying compressed air. This air inlet 25 has a first air inlet 25a and a second air inlet 25b.

[0040] The base 20 is formed in a substantially cylindrical shape, for example, from stainless steel, with a tapered diameter near its center. A bottomed recessed hole 26 is provided in the upper, wider cylindrical portion, with an inner diameter capable of forming a small cylinder chamber Cs (described later). A smaller diameter through-hole 27 is formed continuing from this recessed hole 26 to the lower end of the base 20. A connecting portion 28, which connects to the body 14, is provided at the lower part of the base 20, with a larger diameter than the central portion. A male threaded portion 29 is formed on the outer circumference of the lower end of this connecting portion 28. On the other hand, the inner diameter of the upper opening side of the base 20 is larger than the inner diameter of the recessed hole 26, and a female thread 30 is formed on its inner circumference.

[0041] Near the bottom of the concave hole 26, the first air inlet 25a is formed so as to communicate with the concave hole 26. An external first air passage 31 is connected to this first air inlet 25a, and compressed air supplied through the first air passage 31 can be supplied to the small cylinder chamber Cs through the first air inlet 25a.

[0042] Case 21 is formed in a substantially cylindrical shape from, for example, an aluminum alloy, and a cylindrical portion 32 is provided on its upper side. Inside the cylindrical portion 32, a concave hole 33 is provided, which has a slightly larger inner diameter (volume) than the small cylinder chamber Cs described above, and a large cylinder chamber Cb can be formed by this concave hole 33. The large cylinder chamber Cb is provided with a larger volume than the small cylinder chamber Cs, and is configured such that the thrust when compressed air is supplied to the large cylinder chamber Cb from the second air inlet 25b and the second piston 23b (described later) operates is greater than the thrust when compressed air is supplied to the small cylinder chamber Cs from the first air inlet 25a and the first piston 23a (described later) operates.

[0043] A cylindrical projection 34 is formed at the lower part of the cylindrical portion 32 so as to be smaller in diameter than the outer diameter of the cylindrical portion 32, and a communication hole 35 is formed in the center of the cylindrical projection 34 with an inner diameter approximately the same as the through hole 27. Above the cylindrical projection 34, a male thread 36 is formed which can be screwed into the female thread 30 of the base 20, while the upper end opening side of the cylindrical portion 32 is provided so as to be larger in diameter than the inner diameter of the concave hole 33, and a female thread portion 37 is formed on its inner circumference.

[0044] The cover 22 is formed from, for example, an aluminum alloy, into a cylindrical shape that can cover the upper opening side of the case 21, and a male threaded portion 40 that can be screwed into the female threaded portion 37 of the case 21 is formed on its lower outer circumference. A cylindrical protruding portion 41 is formed in the center of the inside of the cover 22, and a through hole 42 is formed inside this protruding portion 41. The second air inlet 25b is formed on the upper opening side of the through hole 42, and an external second air passage 43 is connected to this second air inlet 25b by screwing, so that compressed air supplied through this second air passage 43 can be supplied to the large cylinder chamber Cb from the second air inlet 25b through the through hole 42.

[0045] The base 20 and case 21 are fixed together by screwing a female thread 30 and a male thread 36, and the case 21 and cover 22 are fixed together by screwing a female thread portion 37 and a male thread portion 40, and these are connected as a single, roughly cylindrical unit. Inside, a piston 23, a spring 24, etc. are housed, respectively, to constitute the actuator 11.

[0046] In this case, the piston 23 is mounted inside the actuator 11 via a spring 24, and the fluid control valve 10 is configured to allow the piston 23 to move toward and away from the valve seat 13 by compressed air from the air intake port 25 or the elastic force of the spring 24, thereby controlling the opening and closing of the flow path 44 provided inside the body 14.

[0047] The piston 23 is formed by dividing an aluminum alloy into multiple sections, and each of these divided pistons 23 is arranged in series with respect to the valve seat 13 in an elastic state through multiple springs 24 with different spring loads. This series state means that, as shown in Figure 1, each piston 23 is arranged in a line on the same axis, aligned in a vertical straight line, and the force transmitted from one piston 23 is easily transmitted to the other piston 23 through direct contact.

[0048] In addition, the first air inlet 25a and the second air inlet 25b are formed in the actuator 11 so as to be able to supply compressed air that moves each divided piston 23 in the opposite direction to the elasticity direction of each spring 24. In this embodiment, the elastic state of each spring refers to the state in which the spring is compressed by a spring load and deforms while accumulating the pressing force. Due to this elasticity (which can also be called resilience), for example, the fluid control valve 10, through the automatic operation of the actuator 11, lowers the piston 23 while compressed air from the air inlet 25 deforms each spring 24, pushing the valve body (diaphragm) 11 against the valve seat 13, thereby creating a tight seal (valve closed state). The elastic state of the spring is maintained when the valve is closed. On the other hand, to open the valve, compressed air is exhausted, releasing the pressure stored in the spring itself. This causes the spring to return to its original shape, raising the piston 23 and separating the valve body (diaphragm) 11 from the valve seat 13, thus opening the valve. In this open state, the spring's elastic state is eliminated. Through these actions, the flow path 44 provided inside the body 14 can be controlled to open and close.

[0049] The fluid control valve 10 is configured such that, as shown in Figure 4, each divided piston 23 moves independently up and down within the actuator 11 by compressed air from the first and second air inlets 25a and 25b, or by the elastic force of each spring 24, with predetermined strokes Y1 and Y2. The diaphragm 12 is configured to seal the flow path 44 with different sealing forces depending on the movement state (downward state) of each of the divided pistons 23 toward the valve seat 13.

[0050] In Figures 1 to 3, the piston 23 has a first piston 23a and a second piston 23b. The first piston 23a is positioned on the primary side, near the diaphragm 12, and the second piston 23b is positioned on the secondary side relative to the diaphragm 12. The first piston 23a and the second piston 23b are configured to move up and down simultaneously, as will be described later, or the first piston 23a can move up and down while the second piston 23b is raised. The first piston 23a is configured to exhibit pressure resistance (sealing performance) of 0.1 MPa or more, and the second piston 23b is configured to exhibit pressure resistance (sealing performance) of 1 MPa or more.

[0051] When the second piston 23b rises, a gap 45 is provided between the opposing surfaces of the shaft portion 70 of the second piston 23b in its raised state and the shaft portion 50 of the first piston 23a, which moves up and down relative to the second piston 23b, as shown in Figure 3.

[0052] The first piston 23a has a cylindrical shaft portion 50 and a cylindrical enlarged diameter portion 51 with one side open (upper opening) formed on the outer circumference near the center of the shaft portion 50. The shaft portion 50 is inserted into the through hole 27 at the lower side and into the communication hole 35 at the upper side, and is provided to slide vertically. In this inserted state, the first piston 23a is positioned in a small cylinder chamber Cs provided between the base 20 and the case 21. The enlarged diameter portion 51 is formed with an outer diameter approximately the same as the inner diameter of the small cylinder chamber Cs. O-rings 52 and 53 for sealing are attached at two locations on the outer circumference of the upper and lower sides of the shaft portion 50 and at one location on the outer circumference of the enlarged diameter portion 51, respectively.

[0053] The O-ring 52 on the lower side of the shaft portion 50 seals the space between the lower outer surface of the shaft portion 50 and the through hole 27, the O-ring 52 on the upper side of the shaft portion 50 seals the space between the upper outer surface of the shaft portion 50 and the communication hole 35, and the O-ring 53 on the enlarged diameter cylindrical portion 51 seals the space between the outer surface of the enlarged diameter cylindrical portion 51 and the inner surface of the concave hole 26. In this manner, the first piston 23a is provided so as to be able to move up and down while forming a small cylinder chamber Cs, with its outer peripheral sliding surface sealed.

[0054] In the through hole 27, a substantially cylindrical rod 54 is mounted in contact with the lower part of the shaft portion 50 of the first piston 23a, and this rod 54 is provided to move up and down within the through hole 27 in conjunction with the up and down movement of the first piston 23a.

[0055] The second piston 23b is composed of three pistons located within the case 21 (large cylinder chamber Cb): an upper piston 60 positioned at the upper part, a middle piston 61 positioned at the center, and a lower piston 62 positioned at the lower part.

[0056] The upper piston 60 is provided with a cylindrical shaft portion 65 and an enlarged disc portion 66 formed on the lower side of the shaft portion 65. Two sealing O-rings 52 are fitted to the outer circumference of the shaft portion 65, and the shaft portion 65 is inserted into the insertion hole 42 in a sealed state so as to be able to slide up and down, and the upper piston 60 is arranged to be able to move up and down within the large cylinder chamber Cb. The disc portion 66 is formed with an outer diameter approximately the same as the inner diameter of the large cylinder chamber Cb. An O-ring 67 for sealing is attached to the outer circumference of the disc portion 66, and this O-ring 67 seals the disc portion 66 and the inner surface of the concave hole portion 33, so that the upper piston 60 is installed in a sealed state inside the large cylinder chamber Cb.

[0057] A through-flow channel 68 is formed in the shaft portion 65 of the upper piston 60, and this through-flow channel 68 is provided in such a manner that compressed air can be supplied from the upper surface side of the shaft portion 65 to the bottom surface side of the disc portion 66 within the large cylinder chamber Cb. Compressed air supplied through the second air inlet 25b is provided so that it can be supplied to the middle piston 61 side and the lower piston 62 side through the through-flow channel 68.

[0058] The central piston 61 is formed in a disc shape and has an outer diameter approximately the same as the inner diameter of the large cylinder chamber Cb. A sealing O-ring 67 is attached to the outer circumference of the central piston 61, and this O-ring 67 seals the central piston 61 and the inner surface of the concave hole 33. A through hole 69 is formed in the center of the central piston 61, and the upper side of the shaft portion 70 of the lower piston 62 (described later) is mounted in the through hole 69 so as to be able to slide up and down, and the central piston 61 is positioned between the upper piston 60 and the lower piston 62.

[0059] The lower piston 62 is provided with a shape having a substantially cylindrical shaft portion 70 and an enlarged disc portion 71 formed on the central side of the shaft portion 70. A sealing O-ring 52 is fitted to the outer circumference of the upper side of the shaft portion 70, and the shaft portion 70 is inserted into the insertion hole 69 of the middle piston 61 in a sealed state so as to be able to slide up and down, and the middle piston 61 and the lower piston 62 are provided so as to be able to move relative to each other. A sealing O-ring 52 is fitted to the outer circumference of the lower side of the shaft portion 70 and is inserted into the communication hole 35 in a sealed state so as to be able to slide up and down, and the lower piston 62 is arranged to be able to move up and down within the large cylinder chamber Cb. A through passage 72 is provided in the shaft portion 70 of the lower piston 62, and this through passage 72 is provided in such a manner that compressed air can be supplied from the upper side of the shaft portion 70 to the bottom side of the disc portion 71 within the large cylinder chamber Cb.

[0060] The second piston 23b is provided within the large cylinder chamber Cb so that the upper piston 60, middle piston 61, and lower piston 62 described above can move up and down independently. In this case, the upper surface of the shaft portion 70 of the lower piston 62 is always in contact with the bottom surface of the disc portion 66 of the upper piston 60, and the middle piston 61 is incorporated between the upper piston 60 and the lower piston 62 so that it can move relative to them. With this structure, the upper and lower pistons 60 and 62 of the second piston 23b can move up and down within the cylindrical portion 32.

[0061] The spring 24 has a first spring 24a and a second spring 24b, and each of these springs 24a and 24b is provided by a coil spring. The spring load of the second spring 24b is set to be greater than the spring load of the first spring 24a, that is, the elastic force of the second spring 24b is greater than the elastic force of the first spring 24a.

[0062] The first spring 24a is installed on the side of the first piston 23a between the inner bottom surface of the enlarged cylindrical portion 51 of the first piston 23a and the bottom surface of the cylindrical portion 32 of the case 21. The elastic force of the first spring 24a biases the first piston 23a downward relative to the base 20. On the other hand, the second spring 24b is installed on the second piston 23b side, between the upper surface of the disc portion 66 of the upper piston 60 of the second piston 23b and the inner opposing surface of the cover 22. The elastic force of this second spring 24b biases the upper piston 60 downward, and the lower piston 62 and the middle piston 61 are integrally biased downward relative to the case 21 with respect to the upper piston 60.

[0063] In this case, as described above, the spring load of the second spring 24b is greater than the spring load of the first spring 24a. As a result, the compressed air pressure required to move the second piston 23b upward against the elastic force of the second spring 24b is greater than the compressed air pressure required to move the first piston 23a upward against the elastic force of the first spring 24a. Consequently, the first piston 23a can be raised and lowered with less force than the second piston 23b.

[0064] Furthermore, the spring load of the first spring 24a is set to be such that, when the second piston 23b is raised, it presses the diaphragm 12 against the valve seat 13 through the first piston 23a, thereby sealing the process gas (material gas) supplied into the flow path 44 of the body 14.

[0065] Furthermore, the sum of the spring loads of the first spring 24a and the second spring 24b is set to a size that seals the pressurized gas supplied into the flow path 44 when the diaphragm 12 is pressed against the valve seat 13 through the first piston 23a and the second piston 23b.

[0066] As described above, the second piston 23b and the second spring 24b are installed inside the case 21, and the first piston 23a and the first spring 24a are installed inside the base 20. The case 21 and the base 20 are then joined together by screws to form the actuator 11 as a single unit.

[0067] After the actuator 11 is installed, in the large cylinder chamber Cb, a first air chamber 81 and a second air chamber 82 are provided between the upper piston 60 and the middle piston 61 of the second piston 23b, and between the lower piston 62 and the bottom surface of the concave hole 33, respectively, and compressed air from the second air inlet 25b can be supplied to the first and second air chambers 81 and 82, respectively. Meanwhile, in the small cylinder chamber Cs, a third air chamber 83 is provided between the enlarged cylindrical portion 51 of the first piston 23a and the bottom surface of the concave hole 26, and compressed air from the first air inlet 25a can be supplied to this third air chamber 83.

[0068] As described above, in the actuator 11, the first and second springs 24a and 24b are installed in an elastic state to lower the divided first and second pistons 23a and 23b and close the diaphragm 12, and the first and second air inlets 25a and 25b are formed in the actuator 11 so that compressed air can be supplied in a direction that raises the respective pistons 23a and 23b and opens the diaphragm 12. As a result, under normal conditions (natural state), the fluid control valve 10 is configured such that the first and second pistons 23a and 23b are pressed down by the elastic biasing force of the first and second springs 24a and 24b, causing the diaphragm 12 to close. On the other hand, when compressed air is supplied from the first and second air inlets 25a and 25b, the first and second pistons 23a and 23b rise against the elastic force of the first and second springs 24a and 24b, and the diaphragm 12 returns to its original position in the valve opening direction due to its elastic force, resulting in the valve opening state. Thus, the actuator 11 of the fluid control valve 10 in this embodiment is configured as a so-called normally closed type.

[0069] Next, the body 14 of the fluid control valve 10 will be described. The body 14 is formed in a substantially cylindrical shape with approximately the same diameter as the actuator 11, and as a result the entire fluid control valve 10 is provided in a small diameter substantially cylindrical shape, which reduces the footprint when used in semiconductor manufacturing equipment, etc.

[0070] Inside the body 14, a primary flow path 91 and a secondary flow path 92 are provided so as to be able to communicate with an external flow path, and a mounting recess 93 is formed at the upper side of these. On the upper inner circumference side of the mounting recess 93, a female threaded portion 94 is formed into which the male threaded portion 29 of the base 20 can be screwed, and an annular mounting portion 96 having a stepped portion 95 is formed on the lower side of this female threaded portion 94. A diaphragm 12 and an annularly formed bonnet 97 are provided in this mounting portion 96 so as to be able to be fitted into it, and a substantially cylindrical diaphragm piece 98 is mounted on the bonnet 97. A sheet-shaped valve seat 13 is mounted on the opening side of the primary flow path 91 in the mounting recess 93, and a valve chamber 99 is provided between this valve seat 13 and the diaphragm 12, and the primary flow path 91 and the secondary flow path 92 are able to be opened and closed by the diaphragm 12 moving toward and away from the valve seat 13.

[0071] The diaphragm 12 is constructed by stacking multiple thin, roughly disc-shaped metal plates (e.g., Spron). In its natural state, as shown in Figure 2, it is arranged in a disc shape that forms a gently convex curved surface with its center as the apex, directed towards one side (upwards). This shape provides it with self-returning elastic force. The diaphragm 12 is mounted on the mounting portion 96, positioned on the upper side of the valve seat 13.

[0072] The bonnet 97 is formed in a cylindrical shape and is mounted on the upper side of the diaphragm 12 at the mounting portion 96. A diaphragm piece 98 is inserted into the center of the bonnet 97 so as to be slidable in the vertical direction. The aforementioned rod 54 is positioned on the upper side of the diaphragm piece 98. After the actuator 11 and the body 14 are integrated, the diaphragm piece 98 is made to move up and down relative to the bonnet 97 through the rod 54 by the up and down movement of the first piston 23a, and the diaphragm piece 98 is made to press the diaphragm 12 toward the valve seat 13.

[0073] The valve seat 13 is formed in a ring shape from a resin material such as a fluororesin, such as PFA (a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene), and is mounted on the valve chamber 99 side so as to be able to seal the diaphragm 12.

[0074] The body 14, with the diaphragm 12, bonnet 97, and diaphragm piece 98 mounted on the mounting portion 96, is fixed to the base 20 by screwing the male thread portion 29 and female thread portion 94 together, thereby forming a fluid control valve 10 in conjunction with the actuator 11. After the body 14 and base 20 are tightened, the bonnet 97 is pressed against the bottom side of the connection portion 28 of the base 20, and the diaphragm 12 is fixed in a predetermined position inside the body 14 through the bonnet 97.

[0075] In the fluid control valve 10 described above, the actuator 11 is of the normally closed type. However, the fluid control valve of the present invention can also be configured as a normally open type, meaning that the diaphragm is in the open position under normal conditions (natural state), while the diaphragm is in the open position when compressed air is supplied.

[0076] In the fluid control valve 10 described above, power is transmitted using a piston 23 having two pistons, a first piston 23a and a second piston 23b, and a spring 24 having two springs, a first spring 24a and a second spring 24b. However, three or more of each of these may be used. In that case, the number of air intake ports may also be increased as appropriate.

[0077] Each O-ring is made from fluororubber, but the material can be changed as appropriate to adjust the sliding properties and sealing performance of the piston, and it is also possible to use various rubber materials other than fluororubber or other materials.

[0078] It is preferable to use, for example, clean dry air as the compressed air supplied from the first and second air inlets 25a and 25b, but it is also possible to use other gases.

[0079] In the above embodiment, the fluid control valve 10 was described as a valve for ALD and ALE in the semiconductor manufacturing process, but it can be used in various other semiconductor manufacturing processes, panel manufacturing processes, and other applications, and can also be used in general applications outside of these fields.

[0080] Next, the operation and function of the fluid control valve of the present invention in the above embodiment will be described. The fluid control valve 10 of this embodiment can perform control in response to processes such as supplying material gas to a process chamber (not shown), purging within its body or piping (not shown), or maintenance such as airtightness testing. During the process, the diaphragm 12 is controlled to open and close according to the process mode described later, and during purging and maintenance, the diaphragm 12 is controlled to open and close according to the maintenance mode described later. These process modes and maintenance modes are provided to be switchable at will when controlling the fluid control valve 10.

[0081] In process mode and maintenance mode, Figure 1 shows the fully closed state of the fluid control valve, Figure 2 shows the fully open state of the fluid control valve, and Figure 3 shows the open state of the fluid control valve in process mode. Figure 4 shows the open and closed states of the diaphragm 12 of the fluid control valve 10 in Figures 1 to 3. In this figure, the valve on the left represents the fluid control valve in the state shown in Figure 1, the valve in the center represents the fluid control valve in the state shown in Figure 2, and the valve on the right represents the fluid control valve in the state shown in Figure 3. In the figure, the dashed lines are provided to compare the positions of the bottom surface of the first piston 23a (shaft portion) and the bottom surface of the second piston 23b (shaft portion of the lower piston), respectively.

[0082] In the fluid control valve 10, when the actuator 11 operates, the rod 54 and the diaphragm piece 98 move in conjunction, and the thrust generated by their operation is transmitted to the diaphragm 12. This allows the fluid flow to be controlled by either sealing the diaphragm 12 tightly against the valve seat 13 to close the valve, or separating the diaphragm 12 from the valve seat 13 to open the valve to a predetermined degree.

[0083] <Maintenance Mode> Maintenance mode is the operating method used when purging the fluid control valve 10 and the piping connected to it, or when performing maintenance on the fluid control valve 10, such as airtightness tests. In maintenance mode, the first piston 23a and the second piston 23b are raised and lowered simultaneously. When these two pistons 23a and 23b are raised, the valve is fully open, and when they are lowered, the valve is fully closed.

[0084] In maintenance mode, under normal circumstances, the supply of compressed air from the first and second air inlets 25a and 25b is stopped. As shown in Figure 1, the upper piston 60 descends inside the case 21 due to the elastic force of the second spring 24b, and the lower piston 62 also descends relative to the base 20, pushed by the upper piston 60. Furthermore, the shaft portion 50 of the first piston 23a is pushed by the shaft portion 70 of the lower piston 62, causing the first piston 23a to also descend relative to the base 20.

[0085] Meanwhile, the first piston 23a descends within the base 20 due to the elastic force of the first spring 24a. At this time, the second piston 23b and the first piston 23a descend simultaneously, and as a result, the first piston 23a is subjected to a combined force from the second piston 23b side due to the elastic force of the second spring 24b and the elastic force of the first spring 24a. This combined force creates a thrust that is applied from above to the diaphragm 12 through the rod 54 and diaphragm piece 98, causing the valve to close.

[0086] At this time, the sum of the spring loads of the first spring 24a and the second spring 24b is set to a size that seals the pressurized gas supplied into the flow path 44 when the diaphragm 12 is pressed against the valve seat 13 through the first piston 23a and the second piston 23b. As a result, the valve provides sufficient sealing performance, ensuring reliable leakage not only when low-pressure material gases (process gases) of about 0.1 MPaG, which are used for flow control in process applications, are flowing, but also when high-pressure gases, such as those of about 0.7 MPaG, which are higher than the material gas, attempt to flow while the valve is closed during purging or maintenance.

[0087] In maintenance mode, when changing from the state shown in Figure 1 to the fully open state, compressed air is supplied from both the first and second air inlets 25a and 25b, as shown in Figure 2. At this time, on the case 21 side, compressed air supplied from the second air inlet 25b flows from the through passage 68 of the upper piston 60 to the through passage 72 of the lower piston 62, and is supplied to the first air chamber 81 between the upper piston 60 and the middle piston 61, and to the second air chamber 82 between the lower piston 62 and the bottom side of the concave hole 33 of the case 21. Due to the pressure of this compressed air, the upper piston 60 and the lower piston 62 rise inside the case 21, and as they move, the middle piston 61 also rises slightly, causing the entire second piston 23b to rise.

[0088] Thus, the second piston 23b has a divided structure consisting of an upper piston 60, a middle piston 61, and a lower piston 62, and compressed air is supplied to the first air chamber 81 and the second air chamber 82, respectively, by supplying compressed air at a predetermined pressure to the bottom surfaces of the predetermined area disc portions 66 and 71 of the upper and lower pistons 60 and 62 simultaneously. This makes it possible to raise the piston more efficiently compared to supplying compressed air at the same pressure to a single piston with the same bottom area.

[0089] Meanwhile, on the base 20 side, compressed air supplied from the first air inlet 25a is supplied to the third air chamber 83 between the first piston 23a and the bottom surface of the concave hole 26 in the base 20. The pressure of this compressed air causes the first piston 23a to rise inside the base 20. At this time, the shaft portion 70 of the lower piston 62 is pushed by the shaft portion 50 of the first piston 23a, causing the lower piston 62 to rise as well. As a result, the combined force of the compressed air from the first air inlet 25a and the compressed air from the second air inlet 25b acts on the entire first and second pistons 23a and 23b, and these first and second pistons 23a and 23b rise against the resilience of the first and second springs 24a and 24b due to the thrust from this combined force.

[0090] As the first and second pistons 23a and 23b rise, the pressure on the diaphragm 12 via the rod 54 and diaphragm piece 98 is released, and the diaphragm 12, with its self-returning elastic force, pushes up the diaphragm piece 98 and rod 54, separating from the valve seat 13 and opening the valve. In this valve-open state, during maintenance mode, pressurized gas (compressed air) can be flowed from the primary side passage 91 to the secondary side passage 92 during purging or maintenance. In these cases, the body of the fluid control valve 10 and the piping are purged with a high pressure, for example, 0.7 MPaG or higher, to reduce the residual process gas.

[0091] In maintenance mode, it is not necessary to repeatedly raise and lower the first and second pistons 23a and 23b in a short period of time. Instead, the first and second pistons 23a and 23b are held in an elevated or lowered position while purging and maintenance are performed. In this way, the combined force of the elastic forces of the first and second springs 24a and 24b acts mainly as a static load on the diaphragm 12 and valve seat 13, preventing impact loads on the diaphragm 12 and valve seat 13, thereby preventing deformation or damage.

[0092] <Process Mode> The process mode is the operating method when supplying material gas from the fluid control valve 10 to a process chamber (not shown). In process mode, with the second piston 23b raised, only the first piston 23a can be moved up and down. When the second piston 23b is raised, the valve opens when the first piston 23a rises and closes when it descends.

[0093] In process mode, the valve is open, similar to the fully open state shown in Figure 2 of the maintenance mode described above. Compressed air is supplied from both the first and second air inlets 25a and 25b, causing the first and second pistons 23a and 23b to rise and the diaphragm 12 to open. The valve opening and closing operation in process mode is performed by raising and lowering the first piston while the second piston 23b is raised, as described above. In other words, by operating the first piston 23a from the fully open state of the maintenance mode, a smooth transition to process mode is possible.

[0094] In process mode, when changing from the state shown in Figure 2 to the valve closed state, as shown in Figure 3, the supply of compressed air from the second air inlet 25b is maintained while the supply of compressed air to the first air inlet 25a is stopped.

[0095] At this time, inside the case 21, compressed air is supplied to the first and second air chambers 81 and 82, respectively, just as in the fully open state of maintenance mode. The pressure of this compressed air causes the entire second piston 23b to rise inside the case 21.

[0096] Meanwhile, on the base 20 side, the first piston 23a descends due to the elastic force of the first spring 24a when the compressed air supply to the first air inlet 25a is stopped. At this time, the first piston 23a is not subjected to any pressing force from the second piston 23b side by the second spring 24b, and the valve closes with only the thrust from the first spring 24a applied to the diaphragm 12 through the rod 54 and diaphragm piece 98.

[0097] In this case, the spring load of the second spring 24b is set to be greater than the spring load of the first spring 24a, and the elastic force of the first spring 24a, which is smaller than that of the second spring 24b, is applied to the first piston 23a. Therefore, in the valve closed state in process mode, the thrust of the first piston 23a can be kept smaller compared to maintenance mode, and the pressing force toward the valve seat 13 can be significantly reduced. As a result, even if the first piston 23a is repeatedly raised and lowered in process mode to control the supply amount of low-pressure material gas, the load on the diaphragm 12 and valve seat 13 can be kept small, preventing deformation or damage to them.

[0098] Furthermore, the spring load of the first spring 24a is set to a size that can seal the material gas supplied into the flow path 44 when the second piston 23b is raised and presses the diaphragm 12 against the valve seat 13 through the first piston 23a. As a result, in the valve closed state, the material gas is reliably sealed by the pressing force of the first piston 23a against the valve seat 13 by the first spring 24a. Specifically, the pressure of the material gas is 0.1 MPaG, which is lower than the maximum operating pressure of 0.7 MPaG for the pressure gas used in maintenance mode. Therefore, the elastic force of the first spring 24a provides sufficient sealing performance, reliably preventing leakage.

[0099] When the first piston 23a moves up and down with the second piston 23b in the raised position, a gap 45 is provided between the opposing surfaces of the second piston 23b and the raised first piston 23a, that is, between the tip surfaces of their opposing shaft portions 50 and 70. Therefore, when the first piston 23a rises during process mode, the first piston 23a does not come into contact with the raised second piston 23b, thereby allowing the first piston 23a to operate smoothly.

[0100] In process mode, high-speed opening and closing control of the diaphragm 12 is required when supplying material gas to the process chamber. To address this, the valve opening and closing operation is performed solely by the first piston 23a within the narrow volume of the small cylinder chamber Cs. In this case, during valve opening, the volume of the third air chamber 83 in the small cylinder chamber Cs becomes significantly smaller than the total volume of the cylinder as a whole, i.e., the sum of the volumes of the first to third air chambers in the small cylinder chamber Cs and the large cylinder chamber Cb. This allows the third air chamber 83 to be filled in a short time with a small amount of compressed air supply, raising the first piston 23a and opening the valve. On the other hand, during valve closing, the first spring 24a, which has a smaller spring load than the second spring 24b, allows for a faster response speed while reliably lowering the first piston 23a and closing the valve.

[0101] At this time, the diaphragm 12 and valve seat 13 are repeatedly subjected to impactful dynamic loads due to the high-speed opening and closing operation. However, as described above, the first piston 23a is raised and lowered by the first spring 24a, which has a smaller spring load than the second spring 24b, and when the valve is closed, the force acting mainly on the diaphragm 12 and valve seat 13 is mainly from the first piston 23a. Therefore, compared to a typical fluid control valve (not shown) in which the piston pressing force does not change during maintenance and process, the load on the diaphragm 12 and valve seat 13 is kept low, the transfer of force from the valve seat 13 to the diaphragm 12 is reduced, and deformation and damage to these components can be prevented.

[0102] Comparing the maintenance mode and process mode described above, in Figure 4, in maintenance mode, when the valve is fully closed, it is in the state of the left valve (state in Figure 1), and when fully open, it is in the state of the center valve (state in Figure 2). Compared to the fully open position in the center, when the left side is fully closed, the second piston 23b is in a lowered position by stroke Y2, and consequently, the first piston 23a is in a lowered position by stroke Y1.

[0103] When the valve is closed, as the first piston 23a descends, a downward force from the second piston 23b is also applied. As a result, the first piston 23a is subjected to a force equal to the sum of the spring loads of the first spring 24a and the second spring 24b, which increases the sealing force when the valve is closed.

[0104] On the other hand, in process mode, when the valve is closed, it is in the state of the valve on the right (state shown in Figure 3), and when fully open, it is in the state of the valve in the center (state shown in Figure 2), similar to the fully closed state in maintenance mode. Compared to the case where the valve on the right side is open, when the valve on the left side is closed, the second piston 23b is in a lowered position by the stroke Y2, and the first piston 23a is in the same lowered position as when the valve on the right side is open. At this time, since a gap 45 is provided between the second piston 23b and the first piston 23a, no force is applied from the second piston 23b side to the first piston 23a side.

[0105] Therefore, when the valve is closed, as the first piston 23a descends, only the force due to the spring load of the first spring 24a acts on the first piston 23a, and the sealing force when the valve is closed is lower than when it is fully closed in maintenance mode. At that time, the spring load of the first spring 24a is set to a size that can seal the material gas supplied into the flow path 44, so that the material gas is reliably sealed.

[0106] In the first piston 23a, the downward movement by the first spring 24a and the upward movement by compressed air from the first air inlet 25a allow the valve opening and closing response speed in process mode to be reduced to about 1 / 4 compared to maintenance mode.

[0107] In process mode, compared to maintenance mode, the load (surface pressure) on the surface of the valve seat 13 is reduced, resulting in less residual stress on the valve seat 13. Since its deformation is almost entirely within the elastic deformation range, the valve seat 13 is less prone to deformation and surface roughness. In this case, compared to the maintenance mode, the surface pressure on the valve seat 13 when the valve is closed can be reduced to about 1 / 3 or less, so that virtually no residual stress remains. This makes it possible to minimize changes in the Cv value and stabilize it.

[0108] In this case, for example, a maximum stress of 5.33 MPa and a maximum residual stress of 0.001 MPa are generated in the valve seat 13 when the valve is closed, whereas in the case of a typical piston-integrated fluid control valve under the same conditions, a maximum stress of 10.24 MPa and a maximum residual stress of 2.48 MPa are generated in the valve seat when the valve is closed. Thus, the fluid control valve 10 of this embodiment can significantly reduce the maximum stress and maximum residual stress compared to a piston-integrated fluid control valve.

[0109] In the maintenance mode described above, when the valve is closed, compressed air is discharged from the first and second air inlets 25a and 25b of the actuator 11. When the valve is opened, compressed air supplied from the first and second air inlets 25a and 25b is required to generate thrust to raise the first piston 23a and the second piston 23b.

[0110] In contrast, in process mode, when the valve is closed, compressed air is supplied to the second air inlet 25b, and compressed air is discharged from the first air inlet 25a. When the valve is opened, compressed air supplied from the first air inlet 25a is needed to generate thrust to raise the first piston 23a from this state.

[0111] In other words, in maintenance mode, the minimum number of operating pistons is three in total: the first piston 23a, the upper piston 60 of the second piston 23b, and the lower piston 62. In contrast, in process mode, only the first piston 23a is required, and compressed air only needs to be drawn in and exhausted to the first air inlet 25a for each valve opening and closing cycle. As a result, the amount of compressed air consumed is reduced compared to maintenance mode, leading to energy savings. In this case, the outer diameter of the first piston 23a is smaller than that of the second piston 23b, and the volume inside the cylinder is also smaller, so the required amount of compressed air can be reduced to 1 / 5 or less. This small amount of compressed air enables piston operation in process mode, allowing for a smaller piston diameter.

[0112] In maintenance mode, in both valve opening and valve closing operations, the upper piston 60 and lower piston 62 of the first piston 23a and second piston 23b are mainly moved up and down by compressed air from the first and second air inlets 25a and 25b, or by the first and second springs 24a and 24b, so that the nine O-rings 52, 53, and 67 attached to them slide inside the actuator 11.

[0113] In contrast, in process mode, in both valve opening and valve closing operations, only the lower piston 62 moves up and down due to compressed air from the first air inlet 25a or the first spring 24a, so that the three O-rings 52 and 67 attached to this lower piston 62 slide inside the actuator.

[0114] Based on these factors, the process mode exhibits less sliding resistance from the O-rings during piston movement compared to the maintenance mode, and also reduces wear on each O-ring. In this case, because there are fewer sliding O-rings and their outer diameters are smaller, it becomes possible to reduce the sliding resistance to less than two-thirds.

[0115] In both maintenance mode and process mode, when fully open, the first and second pistons 23a and 23b rise, causing the diaphragm 12 to deform significantly and creating a wide opening between the primary flow path 91 and the secondary flow path 92. As a result, it becomes possible to quickly perform process steps or maintenance steps such as purging and airtightness testing in a short time by flowing pressurized gas and material gas at predetermined flow rates.

[0116] In this case, a stroke Y1 is required to move from the fully open state to the valve open state, and the upward stroke when the diaphragm piece 98 moves is approximately the same as the stroke Y1. This stroke Y1, which is longer than the stroke Y2, allows the diaphragm 12 to deform significantly when fully open, thereby ensuring a wide opening between the primary flow path 91 and the secondary flow path 92.

[0117] As described above, the fluid control valve in the above embodiment of the present invention allows for variable valve opening and closing times in process mode and maintenance mode, which have different operating pressures. This is achieved by varying the pressing force of the piston 23 on the diaphragm 12 when the valve is closed (fully closed), i.e., the thrust of the actuator 11, thereby reducing stress and load on the diaphragm 12 and valve seat 13 in process mode compared to maintenance mode. This prevents deterioration of sealing performance due to long-term use, improves durability, enhances the stability of the Cv value, and enables highly accurate flow rate control. For example, if nitrogen gas is used as the material gas for the fluid control valve 10, and the fluid is controlled under conditions of a temperature of 250°C and a pressure of 0.1 MPa, the change in the Cv value can be kept to 1.2 ± 3%, while withstanding 25 million opening and closing operations.

[0118] In this case, during process mode, the valve is opened and closed by reciprocating only the first piston 23a, which is elastically biased by the first spring 24a, which has a smaller spring load than the second spring 24b. This not only maintains the sealing performance when the valve is closed, but also reduces the load on the compressed air used to drive the piston 23, enabling high-speed vertical movement of the piston 23. In particular, it is possible to provide a fluid control valve suitable for ALD and ALE.

[0119] While embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from its spirit. [Explanation of Symbols]

[0120] 10 Fluid control valve 11 Actuators 12. Diaphragm (valve body) 13 valve seats 23 pistons 23a First piston 23b Second piston 24 Springs 24a First Spring 24b Second Spring 25 Air intake 25a First air intake 25b Second air intake 44 channels 45 Gap Y1, Y2 stroke

Claims

1. A fluid control valve in which a piston is mounted inside an actuator via a spring, and this piston opens and closes a flow path by bringing a valve body into contact with a valve seat by compressed air from an air intake port or the elastic force of the spring, wherein the piston is formed by dividing it into multiple parts, each of these divided pistons is arranged in series with respect to the valve seat in an elastic state through a plurality of springs with different spring loads, and each of the divided pistons is formed in the actuator and supplied with compressed air that moves each of the divided pistons in the opposite direction to the elastic direction of each of the springs, and each of the divided pistons is provided to move up and down individually and independently within the actuator by the compressed air from each of the air intake ports or the elastic force of each of the springs, and the valve body is provided so as to be able to seal the flow path with different sealing forces depending on the downward state of each of the multiple divided pistons.

2. The fluid control valve according to claim 1, wherein each divided piston has a first piston positioned on the primary side near the valve body and a second piston positioned on the secondary side relative to the valve body than the first piston, and the first piston and the second piston are provided to be able to move up and down simultaneously, or the first piston is provided to be able to move up and down when the second piston is raised.

3. The fluid control valve according to claim 2, wherein a first spring is mounted on the first piston side and a second spring is mounted on the second piston side, and the spring load of the second spring is set to be greater than the spring load of the first spring.

4. The fluid control valve according to claim 3, wherein the spring load of the first spring is set to a size that seals the material gas for the semiconductor manufacturing process supplied into the flow path when the second piston is raised and presses the valve body against the valve seat through the first piston.

5. The fluid control valve according to claim 3, wherein the sum of the spring loads of the first spring and the second spring is set to a size that seals the purging or maintenance pressure gas supplied into the flow path when the valve body is pressed against the valve seat through the first piston and the second piston.

6. The fluid control valve according to claim 1, wherein each spring is mounted in an elastic state to lower each of the divided pistons and close the valve body, and each of the air intake ports is formed in the actuator so as to be able to supply compressed air in a direction that raises each of the divided pistons and opens the valve body.

7. The fluid control valve according to claim 2, wherein when the first piston moves up and down while the second piston is raised, a gap is provided between the opposing surfaces of the second piston and the raised first piston.

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