Fluid control valve

Abstract

To provide a fluid control valve for enabling the acceleration of opening / closing operation.SOLUTION: A fluid control valve 1A includes a valve seat 33, a diaphragm member 34 abutting on / separating from the valve seat 33, a driving shaft 22 for operating between a lower limit position where it comes closest to the valve seat 33 for making the diaphragm member 34 abut on the valve seat 33 and an upper limit position where it separates farthest from the valve seat 33 to transmit driving force at least in an abutting direction with respect to the diaphragm member 34, and a spring part 4A for energizing the driving shaft 22 to the side of the lower limit position to generate the driving force, the spring part 4A including a first compression coil spring 42 for energizing the driving shaft 22 to the side of the lower limit position all the time, and a second compression coil spring 43 for energizing the driving shaft 22 to the side of the lower limit position when the driving shaft 22 is between a predetermined position between the lower limit position and the upper limit position, and the upper limit position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fluid control valve comprising a valve seat, a valve element that abuts against or moves away from the valve seat, a drive shaft that operates between a first position where the valve element is closest to the valve seat and abuts against the valve seat, and a second position where the valve element is furthest from the valve seat, and that transmits a driving force to the valve element at least in the abutting direction, and a biasing portion that biases the drive shaft toward the first position to generate the driving force. [Background technology]

[0002] Multiple types of process gases are used in film formation processes in semiconductor manufacturing processes. Fluid control valves are used to control the flow rates of these process gases. For example, the fluid control valve disclosed in Patent Document 1 is known as a fluid control valve. The fluid control valve disclosed in Patent Document 1 is an air-operated on-off valve that controls the contact and separation movement of a diaphragm and a valve seat using an air cylinder to control the flow rate of the process gas.

[0003] Specifically, the description will be made with reference to Figures 9 and 10. Figure 9 is a cross-sectional view of a fluid control valve 100 according to the prior art, showing the fluid control valve 100 in a valve closed state. Figure 10 is a cross-sectional view of a fluid control valve 100 according to the prior art, showing the fluid control valve 100 in an open state.

[0004] First, the valve opening operation of the fluid control valve 100 will be described. Since the fluid control valve 100 is of a normally closed type, when the actuator unit 7 is not operating, the compression coil spring 82 positions the diaphragm member 94 in a valve-closed position in which it abuts against the valve seat 93 (see FIG. 9). Since the actuator unit 7 has a pneumatically driven air cylinder structure, when operating air is supplied to the actuator unit 7 from the pilot port 74, the piston (not shown) in the case 71 moves in the separating direction (upward in FIGS. 9 and 10). Accordingly, the drive shaft 72 connected to the piston is driven in the same direction. Since the spring retainer 83 is connected to the drive shaft 72, it rises against the load of the compression coil spring 82. As a result, the stem 92, which has been pressed down by the spring retainer 83, rises in the separating direction (upward in FIGS. 9 and 10) due to the restoring force of the diaphragm member 94. 10, the diaphragm member 94 returns to its spherical crown shape due to the restoring force and moves away from the valve seat 93. This places the fluid control valve 100 in an open state. In this open state, the process gas flows from the valve hole 912 into the valve chamber 911 and is then output to the output flow path 914.

[0005] Here, the load in the contact direction applied to the drive shaft 72 by the compression coil spring 82 will be described with reference to Figure 4. Figure 4 is a graph showing the relationship between the load and stroke of the compression coil spring. More specifically, the dashed line in the graph represents the relationship between the load in the contact direction applied to the drive shaft 72 (spring bearing 83) by the compression coil spring 82 and the stroke of the drive shaft 72 in the fluid control valve 100 according to the conventional technology. Note that the diaphragm member 94 applies a load in the separation direction to the drive shaft 72 (spring bearing 83) due to its restoring force, and therefore the load referred to here is a value obtained by subtracting the load generated by the diaphragm member 94 from the spring load of the compression coil spring 82.

[0006] The stroke on the horizontal axis represents the position of the drive shaft 72, with 0% stroke meaning that the drive shaft 72 is at its lowest position and 100% stroke meaning that the drive shaft 22 is at its highest position. The numbers in parentheses on the horizontal axis represent the valve opening of the fluid control valve 1A. When the drive shaft 22 is at its lowest position (0% stroke), the fluid control valve 1A is in a closed state, so the valve opening is 0%. When the drive shaft 22 is at 80% stroke, the diaphragm member 34 returns to its spherical crown shape, so the valve opening of the fluid control valve 1A is at its maximum, so the valve opening is 100%. The load on the vertical axis is represented as 100% when the drive shaft 22 is at its lowest position (0% stroke).

[0007] Looking at the graph, as the drive shaft 72 moves away from the lower limit position (i.e., as the stroke increases), the load on the drive shaft 72 increases linearly. This is because the compression coil spring 82 is compressed as the drive shaft 72 moves away. When the drive shaft 72 reaches the upper limit position (100% stroke), the load reaches 200%.

[0008] Next, the valve closing operation of the fluid control valve 100 will be described. When the fluid control valve 100 is in the valve open state, the supply of operating air to the pilot port 74 is stopped and the operating air is discharged from the pilot port 74. The load of the compression coil spring 82 (200% load in FIG. 4) drives the spring retainer 83 in the contact direction (downward in FIGS. 9 and 10). The spring retainer 83 presses the stem 92, moving it in the same direction. As the stem 92 moves, the diaphragm member 94 is deformed and contacts the valve seat 93. When the diaphragm member 94 contacts the valve seat 93, the fluid control valve 100 enters the valve closed state, as shown in FIG. 9. In the valve closed state, a seal is formed between the diaphragm member 94 and the valve seat 93, blocking the flow of process gas from the valve orifice 912 to the valve chamber 911. In other words, the fluid control valve 100 starts to close the valve due to the load of the compression coil spring 82 (200% load in Figure 4), and the seal is maintained when the valve is closed due to the load of the compression coil spring 82 (100% load in Figure 4). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2017-223318 Summary of the Invention [Problem to be solved by the invention]

[0010] With the recent advancement of miniaturization in semiconductors, there is a demand for faster opening and closing operations of fluid control valves. To achieve this, it is desirable that the load exerted by the compression coil spring during the valve opening operation be as low as possible and that the load during the valve closing operation be as high as possible. The reasons for this are as follows.

[0011] The valve-opening operation is performed by the actuator unit 7 pulling up the spring retainer 83 against the load of the compression coil spring 82, and therefore the lower the spring constant of the compression coil spring 82, the more likely it is that a gap will be created between the spring retainer 83 and the load that raises the piston, making it easier for acceleration to occur.Furthermore, the valve-closing operation is performed by the load of the compression coil spring 82, and therefore the higher the load of the compression coil spring 82, the stronger the force pushing the spring retainer 83 in the contact direction, and the faster the valve-closing operation.

[0012] However, the load of the compression coil spring 82 increases linearly as the opening degree increases (see Figure 4). In other words, since the set load of the compression coil spring 82 is determined by the stroke amount from valve opening to valve closing and the spring constant, conventional fluid control valves have had limitations in increasing the speed of opening and closing operations.

[0013] The present invention has been made in view of the above problems, and has an object to provide a fluid control valve that enables high-speed opening and closing operations. [Means for solving the problem]

[0014] In order to solve the above problems, a fluid control valve according to one aspect of the present invention has the following configuration.

[0015] (1) A fluid control valve comprising: a valve seat; a valve element that abuts against or moves away from the valve seat; a drive shaft that moves between a first position where the valve element is closest to the valve seat and a second position where the valve element is furthest from the valve seat, and that transmits a driving force to the valve element at least in the direction of the abutment; and a biasing unit that biases the drive shaft toward the first position to generate the driving force, wherein the biasing unit comprises a first biasing member that constantly biases the drive shaft toward the first position, and a second biasing member that biases the drive shaft toward the first position when the drive shaft is between a predetermined position between the first position and the second position and the second position.

[0016] (2) In the fluid control valve described in (1), it is preferable that the predetermined position is a position corresponding to a valve opening degree that allows the fluid control valve to obtain a predetermined capacity coefficient.

[0017] (3) In the fluid control valve described in (2), it is preferable that the control fluid is a process gas used in a film deposition process on a wafer, and the predetermined capacity coefficient is a capacity coefficient required for the film deposition process.

[0018] (4) In the fluid control valve according to any one of (1) to (3), it is preferable that the predetermined position is a position that is 60% or more away from the valve seat with respect to the second position.

[0019] According to the above-described fluid control valve, the biasing unit that biases the drive shaft includes a first biasing member and a second biasing member. The first biasing member constantly biases the drive shaft toward the lower limit position (i.e., in the abutting direction of the valve disc), while the second biasing member biases the drive shaft toward the lower limit position (i.e., in the abutting direction) while the drive shaft is in the second position from a predetermined position between the first and second positions. That is, in the first position, only the first biasing member applies a biasing force to the drive shaft, while in the second position, both the first and second biasing members apply a biasing force to the drive shaft. Therefore, the load applied to the drive shaft during the valve opening operation can be adjusted to a level equivalent to that of conventional devices by adjusting the biasing force of the first biasing member, while the load applied to the valve disc during the valve closing operation can be adjusted to a higher level by using the first and second biasing members. If the load applied to the valve disc during the valve closing operation can be adjusted to be higher than before, it is possible to close the valve faster than before. Also, if the load applied to the drive shaft during the valve opening operation can be adjusted to be the same as before, it is possible to maintain the same speed of the valve opening operation. Therefore, the time required for one cycle of the valve closing operation and the valve opening operation can be shortened compared to before. [Effects of the Invention]

[0020] According to the fluid control valve of the present invention, it is possible to increase the speed of opening and closing operations. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view of a fluid control valve according to an embodiment of the present invention, showing the fluid control valve in a valve closed state. [Figure 2] 1 is a cross-sectional view of a fluid control valve according to an embodiment of the present invention, showing the fluid control valve in an open state and the drive shaft in a predetermined position. [Figure 3] 1 is a cross-sectional view of a fluid control valve according to an embodiment of the present invention, showing a state in which the fluid control valve is in an open state and the drive shaft is in an upper limit position. [Figure 4] 10 is a graph showing the relationship between the load and stroke of a compression coil spring. [Figure 5] 10 is a graph showing the relationship between valve opening and operating time. [Figure 6] FIG. 10 is a cross-sectional view of a fluid control valve according to a modified example, showing the fluid control valve in a valve closed state. [Figure 7] 10 is a cross-sectional view of a fluid control valve according to a modified example, showing the fluid control valve in an open state and the drive shaft in a predetermined position. FIG. [Figure 8] 10 is a cross-sectional view of a fluid control valve according to a modified example, showing a state in which the fluid control valve is in an open state and the drive shaft is in an upper limit position. FIG. [Figure 9] FIG. 1 is a cross-sectional view of a fluid control valve according to a conventional technique, showing the fluid control valve in a closed state. [Figure 10] FIG. 1 is a cross-sectional view of a conventional fluid control valve, showing the fluid control valve in an open state. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of a fluid control valve according to the present invention will be described in detail with reference to the drawings. Note that the drawings used in the description are simplified for the purpose of explanation and do not accurately represent the shape, dimensions, etc.

[0023] (Configuration of fluid control valve) The configuration of a fluid control valve 1A according to this embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the fluid control valve 1A according to this embodiment, showing the fluid control valve 1A in a valve-closed state. FIG. 2 is a cross-sectional view of the fluid control valve 1A according to this embodiment, showing the fluid control valve 1A in an open state and with the drive shaft 22 in a predetermined position (described in detail below). FIG. 3 is a cross-sectional view of the fluid control valve 1A according to this embodiment, showing the fluid control valve 1A in an open state and with the drive shaft 22 in an upper limit position (described in detail below).

[0024] The fluid control valve 1A is a gas valve used in semiconductor manufacturing processes. More specifically, it is installed between a vacuum chamber in which a wafer is placed and a process gas supply source, and is used to control the flow rate of a process gas for performing a film deposition process on the wafer. The film deposition process on the wafer is performed, for example, by atomic layer deposition (ALD).

[0025] The fluid control valve 1A is a normally closed type air operated on-off valve, and as shown in FIG. 1, includes an actuator portion 2A, a valve portion 3A, and a spring portion 4A (an example of a biasing portion).

[0026] (Actuator section) First, the actuator unit 2A will be described. The actuator unit 2A is a pneumatically driven air cylinder. The actuator unit 2A includes a cylindrical case 21, a piston (not shown) installed inside the case 21, and a columnar drive shaft 22 connected to the piston. Furthermore, the actuator unit 2A includes a pilot port 24 for inputting operating air into the case 21 at the end of the case 21 opposite the spring unit 4A (the upper end in FIG. 1).

[0027] The piston in the case 21 is slidable up and down within the case 21 in response to the supply, stop, or discharge of operating air from the pilot port 24 into the case 21. The drive shaft 22 advances and retreats along its axial direction in accordance with the up and down movement of the piston. More specifically, the drive shaft 22 shown in FIG. 1 is in a lower limit position (a first position closest to a valve seat 33, described later), and the drive shaft 22 shown in FIG. 3 is in an upper limit position (a second position farthest from the valve seat 33, described later). The drive shaft 22 advances and retreats between the lower and upper limit positions. The axial direction of the drive shaft 22 is parallel to the up and down direction in FIG. 1 and coincides with the direction in which a diaphragm member 34, described later, approaches and leaves the valve seat 33. The upper side in the figure represents the separation direction, and the lower side represents the contact direction.

[0028] The end of the drive shaft 22 on the spring section 4A side (the lower end in FIG. 1) protrudes from the actuator section 2A and extends into the spring section 4A. A spring bearing 221 for pressing the stem 32 (described later) is connected to the tip of the drive shaft 22 within the spring section 4A. Because the spring bearing 221 is integral with the drive shaft 22, it moves forward and backward in the contact direction or separation direction as the drive shaft 22 operates. An end face 224 of the spring bearing 221 on the stem 32 side presses the stem 32 in the contact direction when the drive shaft 22 is driven in the contact direction.

[0029] Furthermore, in spring bearing 221, a first enlarged diameter portion 222 formed with a larger diameter than the other portions and a second enlarged diameter portion 223 formed with an even larger diameter are provided coaxially with the axis of drive shaft 22, in that order from the actuator unit 2A side. The end face of first enlarged diameter portion 222 on the actuator unit 2A side is referred to as first step portion 222a, and the end face of second enlarged diameter portion 223 on the actuator unit 2A side is referred to as second step portion 223a.

[0030] (About the valve part) Next, the valve portion 3A will be described. The valve portion 3A includes a body 31, a stem 32, a valve seat 33, and a diaphragm member 34 (an example of a valve body). The body 31 includes a cylindrical portion 315 that connects to the spring portion 4A. Furthermore, a valve chamber 311 is formed inside the cylindrical portion 315 of the body 31.

[0031] The valve chamber 311 communicates at the center of its bottom with an input port (not shown) through a valve hole 312 for inputting a process gas into the fluid control valve 1A. Thus, the process gas input from the input port flows into the valve chamber 311 through the valve hole 312. A circular valve seat 33 is fixed to the bottom surface of the valve chamber 311, on the outer circumferential side of the valve hole 312 and coaxially with the valve hole 312. The valve seat 33 is made of, for example, a heat-resistant material such as PI (polyimide) or PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). The valve chamber 311 also communicates with an output flow path 314 on the radially outer side of the valve seat 33. The output flow path 314 is used to output the process gas from the valve chamber 311 to the outside of the fluid control valve 1A.

[0032] The stem 32 is made of, for example, stainless steel. The stem 32 is formed in a generally cylindrical shape, and the surface facing the diaphragm member 34 (the lower end surface in the figure) is a spherical surface 321 that bulges out toward the diaphragm member 34. The stem 32 is held by a holder 35 so that the spherical surface 321 abuts against the diaphragm member 34 and is movable up and down.

[0033] Next, the diaphragm member 34 is made of, for example, a Ni alloy, and is formed so that in its natural state it has a spherical crown shape (the state shown in FIGS. 2 and 3) that bulges toward the drive shaft 22. The diaphragm member 34 also has, on its outer periphery, a flat edge portion 344 that is perpendicular to the direction of contact and separation. The diaphragm member 34 is fixed to the valve chamber 311 by sandwiching this edge portion 344 between the holder 35 and the body 31.

[0034] The surface of the diaphragm member 34 opposite to the stem 32 is a contact surface 342 that comes into contact with or separates from the valve seat 33. This contact surface 324 comes into contact with or separates from the valve seat 33 as the drive shaft 22 moves forward or backward. More specifically, this is as follows.

[0035] When the drive shaft 22 moves in the abutment direction, the center of the diaphragm member 34 is pressed by the spring bearing 221 and the stem 32. As a result, the center of the diaphragm member 34 is elastically deformed in the abutment direction along the spherical surface 321 of the stem 32. Then, when the drive shaft 22 reaches the lower limit position, the abutment surface 342 abuts against the valve seat 33, and the fluid control valve 1A enters the valve-closed state.

[0036] On the other hand, when the drive shaft 22 moves in the separating direction while the fluid control valve 1A is in the valve closed state, the spring bearing 221 also moves in the separating direction, and the diaphragm member 34 tries to push the stem 32 in the separating direction by its self-returning force and return to its original spherical crown shape. As a result, the diaphragm member 34 moves away from the valve seat 33, and the fluid control valve 1A enters the valve open state. As the diaphragm member 34 returns to its original spherical crown shape, the distance between the diaphragm member 34 and the valve seat 33 increases (i.e., the valve opening increases), and accordingly the capacity coefficient (Cv value) of the fluid control valve 1A increases.

[0037] When the drive shaft 22 reaches a predetermined position (the position shown in FIG. 2) between the lower limit position and the upper limit position, the diaphragm member 34 returns to its original spherical crown shape, and the fluid control valve 1A reaches its maximum valve opening. By reaching its maximum valve opening, the fluid control valve 1A can obtain a predetermined capacity coefficient required for the film formation process on the wafer by ALD.

[0038] Thereafter, the drive shaft 22 further moves in the separating direction until it reaches the upper limit position shown in Fig. 3. The drive shaft 22 (spring bearing 221) is separated from the stem 32 from the predetermined position to the upper limit position.

[0039] The predetermined position is preferably set to a position that is 60% or more of the upper limit position of the drive shaft 22, and is set to 80% in this embodiment. This is because if the predetermined position were set to less than 60% of the upper limit position, the distance between the drive shaft 22 (spring bearing 221) and the stem 32 would be too large when the drive shaft 22 is at the upper limit position. A larger distance between the drive shaft 22 (spring bearing 221) and the stem 32 would lengthen the time from when the drive shaft 22 starts to move in the abutment direction until it starts to press the diaphragm member 34, which is undesirable because it would reduce the responsiveness of the fluid control valve 1A. Furthermore, the upper limit of the predetermined position may be 100% or less of the upper limit position of the drive shaft 22, but in reality, it is preferably 95% or less of the upper limit position. This is because if the specified position is set to 100% of the upper limit position, then the point at which the drive shaft 22 reaches its upper limit position will coincide with the point at which the diaphragm member 34 reaches its maximum valve opening, and taking into account manufacturing tolerances, there is a risk that the maximum valve opening will not be achieved.

[0040] (About the spring part) Next, the spring portion 4A will be described. The spring portion 4A includes a first compression coil spring 42 (an example of a first biasing member) positioned coaxially with the drive shaft 22, a second compression coil spring 43 (an example of a second biasing member), and an annular member 44 in the internal space 41. The spring portion 4A also includes a cylindrical protrusion 512 that protrudes toward the valve portion 3A at the center of an end face 511 of the internal space 41 on the actuator portion 2A side.

[0041] The annular member 44 includes a cylindrical sleeve portion 441 through which the drive shaft 22 is inserted, and a flange portion 442 extending radially from the end of the sleeve portion 441 on the actuator unit 2A side. The diameter of the flange portion 442 is approximately the same as the diameter of the first enlarged diameter portion 222 of the spring bearing 221. The annular member 44 is not fixed to the drive shaft 22, and is freely movable along the axial direction of the drive shaft 22 (up and down in the drawing), with the upper limit position being a position where it abuts against a stopper 45 fixed to the drive shaft 22. The upper limit position of the annular member 44 is a position where a gap of a predetermined distance D is formed between the flange portion 442 of the annular member 44 and the protrusion 512 of the internal space 51 when the drive shaft 22 is in the lower limit position (i.e., when the fluid control valve 1A is in the valve-closed state), as shown in FIG.

[0042] The first compression coil spring 42 is positioned between the second step portion 223a of the drive shaft 22 and the end surface 511 of the internal space 51. The free length of the first compression coil spring 42 is set to be longer than the distance from the end surface 511 to the second step portion 223a when the drive shaft 22 is in the lowest position (i.e., when the fluid control valve 1A is in the valve-closed state). In other words, the first compression coil spring 42 is constantly compressed by the end surface 511 and the second step portion 223a. Therefore, the first compression coil spring 42 constantly biases the drive shaft 22 in the abutment direction (downward in the figure) due to its spring load.

[0043] The second compression coil spring 43 is positioned between the first step portion 222a of the drive shaft 22 and an annular member 44 (flange portion 442) attached to the drive shaft 22. The free length of the second compression coil spring 43 is set longer than the distance from the flange portion 442 of the annular member 44, which is in the uppermost position, to the first step portion 222a. As a result, the second compression coil spring 43 holds the annular member 44 in the uppermost position when the drive shaft 22 is in the lowermost position (i.e., when the fluid control valve 1A is in the valve-closed state). When the drive shaft 22 is in the lowermost position, the second compression coil spring 43 does not bias the drive shaft 22 in the abutment direction.

[0044] When the drive shaft 22 moves a predetermined distance D away from the lower limit position, the flange portion 442 comes into contact with the protrusion 512, as shown in Fig. 2. When the drive shaft 22 further moves in the away direction, the second compression coil spring 43 is compressed by the flange portion 442 and the first step portion 222a. Therefore, when the drive shaft 22 is between the position where it has moved the predetermined distance D in the away direction and the upper limit position, the second compression coil spring 43 biases the drive shaft 22 in the contact direction by its spring load.

[0045] The position of the drive shaft 22 spaced from the valve seat 33 by the predetermined distance D is the same as the predetermined position (i.e., a position moved 80% from the upper limit position, which corresponds to the valve opening degree for obtaining a predetermined capacity coefficient required for the ALD film formation process on the wafer). In other words, the second compression coil spring 43 biases the drive shaft 22 in the abutment direction when the drive shaft 22 is between the predetermined position and the upper limit position.

[0046] Furthermore, because the first compression coil spring 42 always biases the drive shaft 22 in the abutting direction, when the drive shaft 22 is between a predetermined position and an upper limit position, it is biased in the abutting direction by both the first compression coil spring 42 and the second compression coil spring 43. When the drive shaft 22 is between a lower limit position and a predetermined position, it is biased in the abutting direction only by the first compression coil spring 42. In other words, when the fluid control valve 1A is in a valve-closed state, the seal between the diaphragm member 34 and the valve seat 33 is maintained by the load of the first compression coil spring 42.

[0047] The relationship between the load generated by the compression coil springs 42, 43 and the position of the drive shaft 22 as described above can be summarized as shown in the graph in Figure 4. Figure 4 is a graph showing the relationship between the load and stroke of the compression coil springs. More specifically, the solid line in the graph represents the relationship between the load in the contact direction applied to the drive shaft 22 by the compression coil springs 42, 43 and the stroke of the drive shaft 22 in the fluid control valve 1A. Note that the diaphragm member 34 applies a load in the separation direction to the drive shaft 22 due to its restoring force, and therefore the load referred to here is the spring load of the compression coil springs 42, 43 minus the load generated by the diaphragm member 34.

[0048] The stroke on the horizontal axis represents the position of the drive shaft 22, with 0% stroke meaning that the drive shaft 22 is at its lowest position, 80% stroke meaning that the drive shaft 22 is at its specified position, and 100% stroke meaning that the drive shaft 22 is at its highest position. The numbers in parentheses on the horizontal axis represent the valve opening of the fluid control valve 1A. When the drive shaft 22 is at its lowest position (0% stroke), the fluid control valve 1A is in a closed state, so the valve opening is 0%. When the drive shaft 22 is at its specified position (80% stroke), the diaphragm member 34 returns to its spherical crown shape, so the valve opening of the fluid control valve 1A is maximized, so the valve opening is 100%. The load on the vertical axis represents the load when the drive shaft 22 is at its lowest position (0% stroke) as 100%.

[0049] 4, when the drive shaft 22 is at the lowest position (stroke 0%), that is, when the fluid control valve 1A is in a valve closed state (valve opening 0%), the load applied to the drive shaft 22 is the same as that of the fluid control valve 100 according to the conventional technology (see the dashed line in the graph). However, since the second compression coil spring 43 is not compressed at this point, only the load of the first compression coil spring 42 is applied to the drive shaft 22.

[0050] Then, as the drive shaft 22 moves toward the upper limit position (as the stroke increases), the load applied to the drive shaft 22 increases. This is because the compression amount of the first compression coil spring 42 increases. Until the stroke reaches 80%, the rate of increase in the load is the same as that of the fluid control valve 100 according to the prior art.

[0051] Then, when the stroke reaches 80% (when the drive shaft 22 has moved a predetermined distance D), i.e., when the drive shaft 22 is positioned at a predetermined position, the valve opening of the fluid control valve 1A reaches its maximum (100%), and the load suddenly rises to approximately 200%. This occurs because the flange portion 442 abuts against the protrusion 512, and compression of the second compression coil spring 43 begins. From this point to the upper limit position (100% stroke), both the first compression coil spring 42 and the second compression coil spring 43 apply a load to the drive shaft 22. Thereafter, the load further increases as the stroke increases, and when the drive shaft 22 reaches the upper limit position (100% stroke), the load reaches approximately 320%. This is approximately 1.6 times the load (approximately 200%) at which the drive shaft 72 of the prior art fluid control valve 100 reaches 100% stroke.

[0052] The relationship between the load and stroke has been explained above using the case where the drive shaft 22 moves from the lower limit position to the upper limit position (the stroke of the drive shaft 22 increases). However, when the drive shaft 22 moves from the upper limit position to the lower limit position (the stroke of the drive shaft 22 decreases), the opposite of when the stroke increases occurs. In other words, the load decreases from 320% to 300% as it moves from the upper limit position (100% stroke) to the specified position (80% stroke). Then, after the load decreases suddenly at the specified position (80% stroke), it gradually decreases toward 100% until it reaches the lower limit position (0% stroke).

[0053] (Operation of fluid control valve) The fluid control valve 1A having the above-described configuration performs a valve opening operation and a valve closing operation as follows.

[0054] First, the valve opening operation will be described. Because the fluid control valve 1A is a normally closed type, when the actuator unit 2A is not operating, the load of the first compression coil spring 42 causes the drive shaft 22 to be located at its lowest position (0% stroke in FIG. 4), and as shown in FIG. 1, the diaphragm member 34 is in contact with the valve seat 33. In other words, the fluid control valve 1A is in a closed state (0% valve opening in FIG. 4). In this state, when operating air is supplied from the pilot port 24 to the actuator unit 2A, the piston in the case 21 moves in the separating direction. Accordingly, the drive shaft 22 is driven in the same direction against the load of the first compression coil spring 42 (100% load in FIG. 4). As the drive shaft 22 moves in the separating direction, the first compression coil spring 42 is compressed, and the load on the drive shaft 22 increases (see FIG. 4). At this point, the load of the second compression coil spring 43 is not applied to the drive shaft 22.

[0055] Furthermore, as the drive shaft 22 moves in the separating direction, the spring bearing 221 that had been pressing the stem 32 rises, and as the spring bearing 221 rises, the diaphragm member 34 pushes up the stem 32 and gradually returns to its original spherical crown shape. In other words, as the drive shaft 22 moves in the separating direction, the diaphragm member 34 moves away from the valve seat 33. As the diaphragm member 34 moves away from the valve seat 33, the process gas flows from the valve hole 312 into the valve chamber 311, and then is output from the output flow path 314 to the outside of the fluid control valve 1A. Furthermore, as the diaphragm member 34 moves away from the valve seat 33, the capacity coefficient of the fluid control valve 1A increases.

[0056] Then, when the drive shaft 22 moves a distance D away from the lower limit position, that is, when it reaches a predetermined position (FIG. 4: stroke 80%), the diaphragm member 34 returns to its original spherical crown shape as shown in FIG. 2, and the valve opening becomes maximum (FIG. 4: valve opening 100%). At this time, the capacity coefficient of the fluid control valve 1A becomes a predetermined capacity coefficient required for the ALD wafer film formation process. At the same time, the second compression coil spring 43 begins to compress, and the load of the first compression coil spring 42 and the second compression coil spring 43 is applied to the drive shaft 22. This causes the load on the drive shaft 22 to increase rapidly (FIG. 4: load 300%).

[0057] Thereafter, with the loads of the first compression coil spring 42 and the second compression coil spring 43 applied to the drive shaft 22, the drive shaft 22 further moves toward the upper limit position. As a result, the drive shaft 22 (spring bearing 221) moves away from the stem 32, and the first compression coil spring 42 and the second compression coil spring 43 are further compressed, further increasing the load (see FIG. 4). When the drive shaft 22 reaches the upper limit position shown in FIG. 3 (100% stroke in FIG. 4), the valve-opening operation ends. At this time, the load applied to the drive shaft 22 is 320% (see FIG. 4).

[0058] Next, the valve closing operation will be described. When the drive shaft 22 is in the upper limit position, a load (320% load in Figure 4) is applied to the drive shaft 22 by the compression coil springs 42, 43. Therefore, when the supply of operating air to the pilot port 24 is stopped and the operating air is discharged while the drive shaft 22 is in the upper limit position, the load (320% load in Figure 4) by the compression coil springs 42, 43 drives the drive shaft 22 in the contact direction.

[0059] When the drive shaft 22 reaches the predetermined position shown in FIG. 2 (stroke 80% in FIG. 4), the compression of the second compression coil spring 43 by the protrusion 512 is released. Therefore, once the drive shaft 22 reaches the predetermined position, the spring load of the second compression coil spring 43 is no longer applied to the drive shaft 22. Meanwhile, the spring load of the first compression coil spring 42 continues to be applied to the drive shaft 22. From this point on, the spring retainer 221 comes into contact with the stem 32, and the spring retainer 221 and the stem 32 begin to press the diaphragm member 34. This causes the center of the diaphragm member 34 to elastically deform and move closer to the valve seat 33, thereby reducing the valve opening. When the drive shaft 22 reaches the lower limit position (stroke 0% in FIG. 4), the diaphragm member 34 comes into contact with the valve seat 33 (valve opening 0% in FIG. 4), and the fluid control valve 1A enters the valve-closed state, as shown in FIG. 1. In the valve closed state, the flow of process gas from the valve hole 312 to the valve chamber 311 is blocked.

[0060] The operating time required for the above-described valve opening and closing operations will be explained using Fig. 5. Fig. 5 is a graph showing the relationship between the valve opening degree and the operating time. The solid line in the graph represents the fluid control valve 1A according to this embodiment, and the dashed line in the graph represents the fluid control valve 100 according to the prior art.

[0061] First, the valve opening operation of the fluid control valve 100 according to the prior art will be described. At 0 seconds (time t1) in the graph, the supply of operating air to the fluid control valve 100 in the valve closed state begins. The time (the time from time t1 to time t2) from the start of the supply of operating air until the valve opening degree (valve opening degree 100%) at which the capacity coefficient required for the film formation process is obtained is, for example, about 10 milliseconds.

[0062] Next, the valve closing operation of the fluid control valve 100 according to the prior art will be described. The time from when the supply of operating air is stopped until the valve is closed (valve opening 0%) (the time from time t3 to time t5) is approximately 12 milliseconds. Note that the time from time t2 to time t3 in FIG. 5 is the time during which the fluid control valve 100 is maintained in a state where the valve opening is at its maximum. Although FIG. 5 shows this as approximately 10 milliseconds, this is merely an example and can be adjusted as needed to fit the time required for the film formation process.

[0063] Next, the valve opening operation of the fluid control valve 1A according to this embodiment will be described. At 0 seconds (time t1) in the graph, the supply of operating air to the fluid control valve 1A in the valve-closed state is started. The time from the start of the supply of operating air until the drive shaft 22 is positioned at a predetermined position (stroke 80%), that is, the time until the valve opening degree (valve opening degree 100%) at which the capacity coefficient required for the film formation process is obtained (time from time t1 to time t2) is reached is approximately 10 milliseconds. The time from the start of the supply of operating air to the fluid control valve 1A until the valve opening degree is reached to 100% is equivalent to that of the fluid control valve 100 according to the prior art. This is because the load applied to the drive shaft 22 is equivalent to that of the prior art until the stroke of the drive shaft 22 reaches 80% (see FIG. 4).

[0064] Next, the valve closing operation of the fluid control valve 1A according to this embodiment will be described. The time from when the supply of operating air is stopped until the fluid control valve 1A enters the valve closed state (valve opening 0%) (time from time t3 to time t4) is approximately 9 milliseconds. This is approximately 1 millisecond faster than the time from when the supply of operating air is stopped until the fluid control valve 100 enters the valve closed state (time from time t3 to time t5) according to the prior art. This is because the load applied to the drive shaft 22 when the drive shaft 22 is at its upper limit position (stroke 100%) is approximately 1.6 times the load when the drive shaft 72 of the fluid control valve 100 is at its upper limit position (stroke 100%). Therefore, the drive shaft 22 can be pushed in the contact direction with a larger load than in the prior art. Note that the period from time t2 to time t3 in FIG. 5 is the time during which the fluid control valve 1A is maintained in a state where the valve opening is maximized. Although FIG. 5 shows a time of approximately 10 milliseconds, this is merely an example and is adjusted appropriately to the time required for the film formation process.

[0065] As described above, the fluid control valve 1A can reduce the time required for a valve closing operation by 1 millisecond compared to the fluid control valve 100 according to the prior art. In other words, the time required for one cycle of the valve opening and closing operations can be reduced by approximately 1 millisecond. In some processes, ALD film formation requires 150,000 operations per day, and reducing the takt time by 1 second per cycle can reduce the takt time by 150 seconds per day, or 15 hours per year. This can improve the efficiency of semiconductor manufacturing.

[0066] (Modifications of the fluid control valve) Next, modified examples of the fluid control valve will be described. The above-described fluid control valve 1A has been described as a configuration in which the drive shaft 22 and the diaphragm member 34 are not connected (separate type). However, as in the fluid control valve 1B shown in FIGS. 6 to 8, the drive shaft and the diaphragm member may be connected (integrated type). FIG. 6 is a cross-sectional view of the fluid control valve 1B according to the modified example, showing the fluid control valve 1B in a valve-closed state. FIG. 7 is a cross-sectional view of the fluid control valve 1B according to the modified example, showing the fluid control valve 1B in an open state with the drive shaft 25 in a predetermined position. FIG. 8 is a cross-sectional view of the fluid control valve 1B according to the modified example, showing the fluid control valve 1B in an open state with the drive shaft 25 in an upper limit position.

[0067] The fluid control valve 1B is a normally closed type air operated on-off valve, and as shown in FIG. 6, includes an actuator portion 2B, a valve portion 3B, and a spring portion 4B (an example of a biasing portion).

[0068] (Actuator section) First, the actuator unit 2B will be described. The actuator unit 2B includes a cylindrical case 21, a piston (not shown) installed inside the case 21, a columnar drive shaft 25 connected to the piston, and a pilot port 24.

[0069] The end of drive shaft 25 on the spring section 4 side (the lower end in FIG. 6) protrudes from actuator section 2B and extends into spring section 4B. At the tip of drive shaft 25 within spring section 4B, a first enlarged diameter section 251 formed with a larger diameter than the remaining sections and a second enlarged diameter section 252 formed with an even larger diameter are provided coaxially with the axis of drive shaft 25, in this order from the actuator section 2B side. The end face of first enlarged diameter section 251 on the actuator section 2B side is referred to as first step section 251a, and the end face of second enlarged diameter section 252 on the actuator section 2B side is referred to as second step section 252a.

[0070] An internal thread 255 is formed coaxially with the drive shaft 22 on an end surface 253 of the drive shaft 25 on the valve portion 3B side, so that a valve element 36 (described later) can be screwed onto the internal thread 255. The end surface 253 of the drive shaft 25, together with the valve element 36 screwed onto the internal thread 255, is used to clamp a diaphragm member 37 (described later).

[0071] The other configurations of the actuator section 2B are the same as those of the actuator section 2A of the fluid control valve 1A.

[0072] (About the valve part) Next, the valve portion 3 B will be described. The valve portion 3 B includes a body 31, a valve element 36 (an example of a valve element), a valve seat 33, and a diaphragm member 37.

[0073] The valve element 36 is made of, for example, stainless steel. The valve element 36 has a main body 361 positioned coaxially with the drive shaft 25, and further has an externally threaded portion 362 on the drive shaft 25 side of the main body 361. The valve element 36 is connected to the drive shaft 25 by threading the externally threaded portion 362 into the internally threaded portion 255 of the drive shaft 25. When the valve element 36 is connected to the drive shaft 25, the main body 361 of the valve element 36, together with the end face 253 of the drive shaft 25, sandwiches the diaphragm member 37 from above and below in FIG. 2 .

[0074] The surface of the main body 361 of the valve disc 36 facing the valve seat 33 is a contact surface 364 that contacts and separates from the valve seat 33. Because the valve disc 36 is connected to the drive shaft 25, the contact surface 364 contacts and separates from the valve seat 33 along the axial direction of the drive shaft 25 as the drive shaft 25 moves back and forth. More specifically, as shown in FIG. 6, when the drive shaft 25 is at its lowest position, the valve disc 36 is at a valve-closed position where the contact surface 364 contacts the valve seat 33. As shown in FIG. 8, when the drive shaft 25 is at its highest position, the valve disc 36 is at a maximum valve-opened position where the valve opening is maximized. In other words, the valve disc 36 moves between the valve-closed position and the maximum valve-opened position as the drive shaft 25 moves back and forth. Since the valve element 36 is driven integrally with the drive shaft 25, the lower limit position of the drive shaft 25 corresponds to the valve closed position of the valve element 36, and the upper limit position of the drive shaft 25 corresponds to the valve fully open position of the valve element 36.

[0075] The fluid control valve 1B has a capacity coefficient (Cv value) that increases as the opening degree increases (i.e., as the valve element 36 moves from the valve closed position toward the maximum valve open position). The maximum valve open position is set with a margin relative to the position of the valve element 36 (the position shown in FIG. 7; hereinafter, referred to as the predetermined opening degree) required for the ALD wafer film formation process. In other words, the maximum valve open position of the valve element 36 is set at a position farther from the valve seat 33 than the predetermined opening degree required for the predetermined capacity coefficient. Specifically, the relationship between the maximum valve open position and the predetermined opening degree is preferably set so that the predetermined position is 60% or more of the maximum valve open position, and in this embodiment, it is set to 70%. Because the valve element 36 is driven integrally with the drive shaft 25, this numerical value also applies to the drive shaft 25. In other words, if the position of the drive shaft 25 at which a predetermined opening degree can be obtained is defined as the predetermined position, it is preferable that the relationship between the upper limit position of the drive shaft 25 and the predetermined position is set so that the predetermined position is 60% or more of the upper limit position, and in this embodiment, it is set to 70%.

[0076] Next, the diaphragm member 37 is made of, for example, a Ni alloy, and is formed so as to have a spherical band shape that bulges toward the drive shaft 25 in its natural state. The diaphragm member 37 is sandwiched and fixed at its central portion between the drive shaft 25 and the valve element 36, with its center positioned on an extension of the axial center of the drive shaft 25, and its outer periphery is sandwiched and fixed from above and below within the valve section 3B, as shown in Figure 6. By being fixed in this manner, the diaphragm member 37 divides the interior of the cylindrical portion 315 of the body 31 into the valve chamber 311 and an upper portion thereof, and is adapted to repeatedly elastically deform as the valve element 36 moves in the contact and separation directions.

[0077] The other configurations of the valve portion 3B are the same as those of the valve portion 3A of the fluid control valve 1A.

[0078] (About the spring part) Next, the spring portion 4B will be described. The spring portion 4B includes a first compression coil spring 42 and a second compression coil spring 43, which are positioned coaxially with the drive shaft 25, in an internal space 41. The spring portion 4B also includes a cylindrical projection 512 projecting toward the valve portion 3B at the center of an end face 511 of the internal space 51 on the actuator portion 2 side.

[0079] The first compression coil spring 42 is positioned between the second step portion 252a of the drive shaft 25 and the end face 511 of the internal space 51, and constantly biases the drive shaft 25 in the abutment direction (downward in the figure).

[0080] The second compression coil spring 43 is positioned between the first step portion 251a of the drive shaft 25 and an annular member 44 attached to the drive shaft 25. The second compression coil spring 43 holds the annular member 44 at the upper limit position when the drive shaft 25 is at the lower limit position (i.e., when the valve body 36 is at the valve closed position). Furthermore, when the drive shaft 25 is at the lower limit position (i.e., when the valve body 36 is at the valve closed position), the drive shaft 25 is not biased in the abutment direction by the second compression coil spring 43.

[0081] When the drive shaft 25 moves a predetermined distance D away from the lower limit position, the flange portion 442 comes into contact with the protrusion 512, as shown in Fig. 7. When the drive shaft 25 further moves in the away direction, the second compression coil spring 43 is compressed by the flange portion 442 and the first step portion 251a. Therefore, when the drive shaft 25 is between the position where it has moved the predetermined distance D in the away direction and the upper limit position, the second compression coil spring 43 biases the drive shaft 25 in the contact direction by its spring load.

[0082] The position of the drive shaft 25 spaced from the valve seat 33 by the predetermined distance D is the same as the predetermined position (i.e., a position moved 70% from the upper limit position, and a position at which a predetermined opening is obtained to obtain a predetermined capacity coefficient required for film formation processing of wafers by ALD). In other words, the second compression coil spring 43 biases the drive shaft 25 in the abutment direction when the drive shaft 25 is between the predetermined position and the upper limit position.

[0083] Furthermore, because the first compression coil spring 42 constantly biases the drive shaft 25 in the contact direction, when the valve element 36 is between the predetermined position and the upper limit position, it is biased in the contact direction by both the first compression coil spring 42 and the second compression coil spring 43. When the drive shaft 25 is between the lower limit position and the predetermined position, it is biased in the contact direction only by the first compression coil spring 42. In other words, when the valve element 36 is in the valve-closed position, the seal between the valve element 36 and the valve seat 33 is maintained by the load of the first compression coil spring 42.

[0084] The other configurations of the spring portion 4B are the same as those of the spring portion 4A of the fluid control valve 1A.

[0085] In the fluid control valve 1B configured as described above, when the drive shaft 25 is between a predetermined position and the upper limit position, the drive shaft 25 is urged toward the lower limit position by the first compression coil spring 42 and the second compression coil spring 43, so that when the fluid control valve 1B performs a valve closing operation, the drive shaft 22 can be pushed in the abutment direction with a larger load than in the past. Therefore, the operating time required for the valve closing operation can be shortened compared to the past.

[0086] (About the effects) As described above, the fluid control valve 1A (1B) according to this embodiment has the following features: (1) A valve seat 33, a valve element (e.g., a diaphragm member 34 (valve element 36)) that contacts or separates from the valve seat 33, a drive shaft 22 (25) that operates between a first position (lower limit position) at which the valve element (diaphragm member 34 (valve element 36)) is brought into contact with the valve seat 33 and a second position (upper limit position) at which the valve element is separated from the valve seat 33 the most, and transmits a driving force to the valve element (diaphragm member 34 (valve element 36)) in at least the direction of contact, and a biasing unit (e.g., a biasing unit) that biases the drive shaft 22 (25) toward the first position (lower limit position) to generate the driving force. In the fluid control valve 1A (1B) having the biasing portion (spring portion 4A (4B)), the biasing portion (spring portion 4A (4B)) is characterized in that it comprises a first biasing member (e.g., a first compression coil spring 42) that constantly biases the drive shaft 22 (25) toward the first position (lower limit position), and a second biasing member (e.g., a second compression coil spring 43) that biases the drive shaft 22 (25) toward the first position (lower limit position) when the drive shaft 22 (25) is between the second position (upper limit position) and a predetermined position between the first position (lower limit position) and the second position (upper limit position).

[0087] (2) In the fluid control valve 1A (1B) described in (1), it is preferable that the predetermined position is a position corresponding to a valve opening degree (for example, a valve opening degree of 100%) at which the fluid control valve 1A (1B) can obtain a predetermined capacity coefficient.

[0088] (3) In the fluid control valve 1A (1B) described in (2), it is preferable that the control fluid is a process gas used in a film formation process (e.g., by ALD) of a wafer, and that the predetermined capacity coefficient is a capacity coefficient required for the film formation process.

[0089] (4) In the fluid control valve 1A (1B) described in any one of (1) to (3), it is preferable that the predetermined position is a position that is 60% or more (e.g., 80%) away from the valve seat 33 relative to the second position (upper limit position).

[0090] According to the above-described fluid control valve 1A (1B), the biasing portion (spring portion 4A (4B)) that biases the drive shaft 22 (25) includes a first biasing member (first compression coil spring 42) and a second biasing member (second compression coil spring 43). The first biasing member (first compression coil spring 42) constantly biases the drive shaft 22 (25) toward the lower limit position (i.e., toward the abutment direction of the valve body (diaphragm member 34 (valve body 36))), while the second biasing member (second compression coil spring 43) biases the drive shaft 22 (25) in the abutment direction while the drive shaft 22 (25) is at the second position (upper limit position) from a predetermined position between the first position (lower limit position) and the second position (upper limit position). In other words, at the first position (lower limit position), only the first biasing member (first compression coil spring 42) applies a biasing force (spring load) to the drive shaft 22 (25), while at the second position (upper limit position), both the first biasing member (first compression coil spring 42) and the second biasing member (second compression coil spring 43) apply a biasing force (spring load) to the drive shaft 22 (25). Therefore, the load applied to the drive shaft 22 (25) during the valve opening operation (e.g., between 0% and 80% of the stroke in FIG. 4 ) can be adjusted to a level comparable to that of the conventional valve by adjusting the biasing force (spring load) of the first biasing member (first compression coil spring 42). On the other hand, the load applied to the drive shaft 22 (25) during the valve closing operation (e.g., between 100% and 80% of the stroke in FIG. 4 ) can be adjusted to a level higher than that of the conventional valve by using the first biasing member (first compression coil spring 42) and the second biasing member (second compression coil spring 43). If the load applied to the drive shaft 22 during the valve closing operation can be adjusted to a level higher than that of the conventional valve, the valve closing operation can be performed faster than that of the conventional valve. Furthermore, if the load applied to the drive shaft 22 (25) during the valve opening operation can be adjusted to a level comparable to that of the conventional valve, the valve opening operation can be performed at a speed comparable to that of the conventional valve. Therefore, the time required for one cycle of the valve closing operation and the valve opening operation can be shortened compared to that of the conventional valve.

[0091] The above-described embodiment is merely an example and does not limit the present invention in any way. Therefore, the present invention can naturally be improved and modified in various ways without departing from the spirit and scope of the present invention. For example, the materials of the components of the fluid control valve 1A (1B) according to this embodiment are not limited to those described above. [Explanation of symbols]

[0092] 1A Fluid Control Valve 4A Spring part (an example of a biasing part) 22 Drive shaft 34 Diaphragm member (an example of a valve body) 33 Valve seat 42 First compression coil spring (an example of a first biasing member) 43 Second compression coil spring (an example of a second biasing member)

Claims

1. A valve seat; a valve body that abuts against or separates from the valve seat; a drive shaft that moves between a first position where the valve element is closest to the valve seat and causes the valve element to contact the valve seat, and a second position where the valve element is farthest from the valve seat, and that transmits a drive force to the valve element in at least the direction of contact; a biasing portion that biases the drive shaft toward the first position in order to generate the driving force; A fluid control valve comprising: The biasing portion is a first biasing member that constantly biases the drive shaft toward the first position; a second biasing member that biases the drive shaft toward the first position when the drive shaft is between the second position and a predetermined position between the first position and the second position; To have A fluid control valve comprising:

2. 2. The fluid control valve according to claim 1, the predetermined position corresponds to a valve opening degree at which the fluid control valve can obtain a predetermined capacity coefficient; A fluid control valve comprising:

3. 3. The fluid control valve according to claim 2, The control fluid is a process gas used in a film formation process on a wafer; the predetermined capacitance coefficient is a capacitance coefficient required for the film formation process; A fluid control valve comprising:

4. 4. The fluid control valve according to claim 1, the predetermined position is a position that is 60% or more away from the valve seat with respect to the second position; A fluid control valve comprising:

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