Seals for flow restrictors

Abstract

Devices for controlling gas flow are essential components for delivering process gases used in semiconductor manufacturing. These devices often rely on effectively sealed flow restrictors to eliminate process gas leakage around the flow restrictor. In one embodiment, a seal for a flow restrictor is disclosed. The seal comprises a plastic cylinder that is shrink-fitted to a sealing portion of the flow restrictor. In another embodiment, a seal for a flow restrictor is disclosed. The seal comprises a first sealing ring with a flow aperture, and a flow restrictor mounted in the flow aperture.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 882,814, filed August 5, 2019, which is incorporated herein by reference in its entirety. Background Art

[0003] Mass flow control has long been a key technology in semiconductor chip manufacturing. Equipment used to control mass flow is crucial for providing known process gas flow rates for semiconductor manufacturing and other industrial processes. Such devices are used to measure and accurately control fluid flows in a variety of applications. This control is achieved through the use of precisely calibrated flow restrictors and seals that ensure minimal leakage between the restrictor and the channel in which it is installed.

[0004] As chip manufacturing technology advances, the demand for flow control devices increases. Semiconductor manufacturing processes increasingly require improved performance, including more accurate measurement, lower equipment costs, improved transient response times, and greater consistency in gas delivery times. To achieve this consistent gas delivery, improved flow restrictors and seals are needed. Summary of the Invention

[0005] The present technology relates to seals for flow restrictors used in mass flow controllers or other gas delivery devices. One or more of these gas delivery devices may be used in a wide range of processes, such as semiconductor chip manufacturing, solar panel manufacturing, and the like.

[0006] In one embodiment, the present invention is a seal for a gas flow restrictor having a first end, a second end, and a bore for receiving the flow restrictor to form a fluid-tight connection between the flow restrictor and the seal.

[0007] In another embodiment, the present invention is a valve assembly comprising a valve, a flow restrictor, and a sealing member. The valve has a passageway. The flow restrictor has a first end, a second end, a longitudinal axis extending from the first end to the second end, and a sealing portion located along the longitudinal axis between the first end and the second end. The sealing member contacts the sealing portion of the flow restrictor and the passageway of the valve.

[0008] In another embodiment, the present invention is a valve assembly comprising a valve having a first passage, a second passage, a first sealing recess, and a second sealing recess. The valve assembly comprises a base having a third sealing recess and a fourth sealing recess. The valve assembly comprises a flow restrictor having a first end, a second end, a longitudinal axis extending from the first end to the second end, and a surface of the flow restrictor located between the first end and the second end along the longitudinal axis. Finally, the valve assembly comprises a seal that contacts the surface of the flow restrictor and the first sealing recess of the valve.

[0009] Further areas of applicability of the present technology will become apparent from the detailed description provided hereinafter.It should be understood that the detailed description and specific examples, while indicating the preferred embodiment, are intended for purposes of illustration only and are not intended to limit the scope of the present technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The presently disclosed invention will become more fully understood from the detailed description and accompanying drawings, in which:

[0011] Figure 1 is a schematic diagram of a process using one or more flow restrictors.

[0012] Figure 2 Yes, you can Figure 1 Schematic diagram of the mass flow controller used in the process.

[0013] Figure 3 is a schematic diagram of a valve that incorporates Figure 2 A first embodiment of a flow restrictor and seal for a mass flow controller.

[0014] Figure 4 is available for Figure 3 A perspective view of a first embodiment of a flow restrictor and seal of a valve.

[0015] Figure 5 yes Figure 4 A cross-sectional view of the flow restrictor and seal taken along line VV.

[0016] Figure 6 yes Figure 4 A perspective view of a flow restrictor without a seal.

[0017] Figure 7 yes Figure 4 A perspective view of the seal without a flow restrictor.

[0018] Figure 8 is a schematic diagram of a valve that incorporates Figure 2 A second embodiment of a flow restrictor and seal for a mass flow controller.

[0019] Figure 9 is available for Figure 8 A perspective view of a second embodiment of a valve flow restrictor and seal.

[0020] Figure 10 yes Figure 9 Cross-sectional view of the flow restrictor and seal taken along line XX.

[0021] Figure 11 yes Figure 9 A perspective view of the seal without a flow restrictor.

[0022] Figure 12 yes Figure 11 A cross-sectional view of the seal taken along line XII-XII.

[0023] Figure 13 yes Figure 11 Front view of the seal.

[0024] Figure 14 yes Figure 11 Top view of the seal. DETAILED DESCRIPTION

[0025] The description of the illustrative embodiments according to the principles of the present invention is intended to be read in conjunction with the accompanying drawings, which are considered to be part of the entire written description. In the description of the embodiments of the present invention disclosed herein, any reference to direction or orientation is only for the convenience of description and is not intended to limit the scope of the present invention in any way. Relative terms, such as "lower", "upper", "horizontally", "vertically", "above", "below", "upward", "downward", "left", "right", "top" and "bottom" and their derivatives (e.g., "horizontally", "downwardly", "upwardly", etc.) should be interpreted as referring to the directions shown in the drawings described or discussed later. These relative terms are only for ease of description and do not require the device to be constructed or operated in a specific direction unless explicitly stated. Terms such as "attach", "fix", "connect", "couple", "interconnect" and similar terms refer to a relationship in which structures are fixed or connected to each other directly or indirectly through an intermediate structure, as well as a removable or rigid attachment or relationship between the two, unless explicitly stated otherwise. In addition, the features and advantages of the present invention are illustrated with reference to preferred embodiments. Therefore, the present invention expressly should not be limited to such preferred embodiments illustrating some possible non-limiting combinations of features that may exist alone or in other combinations of features; the scope of the present invention being defined by the appended claims.

[0026] The present invention relates to a seal for a flow restrictor in a device for controlling gas flow. In some embodiments, the device can be used as a mass flow controller to deliver a known mass flow of gas to a semiconductor or similar process. Semiconductor manufacturing is an industry that requires high-performance gas flow control. As semiconductor manufacturing technology advances, customers have recognized the need for flow control devices with greater accuracy and repeatability in delivering gas flow quality. Modern semiconductor processes require strict control of gas flow quality, minimized response time, and highly accurate gas flow. The seal of the present invention ensures that the flow restrictor is more effectively sealed in its flow channel and at a reduced cost.

[0027] Figure 1 A schematic diagram of an exemplary processing system 1000 using one or more flow restrictors is shown. The processing system 1000 can utilize multiple flow control devices 100 fluidly coupled to a processing chamber 1300. The multiple flow control devices 100 are used to supply one or more different process gases to the processing chamber 1300. Items such as semiconductors can be processed within the processing chamber 1300. A valve 1100 isolates each flow control device 100 from the processing chamber 1300, allowing each flow control device 100 to be selectively connected to or isolated from the processing chamber 1300, thereby facilitating various different processing steps. The processing chamber 1300 can include an applicator to apply the process gases delivered by the multiple flow control devices 100, thereby enabling selective or diffuse distribution of the gases supplied by the multiple flow control devices 100. In addition, the processing system 1000 may further include a vacuum source 1200, which is isolated from the processing chamber 1300 by a valve 1100 to enable evacuation of process gases or facilitate purging of one or more flow control devices 100 to enable switching between process gases within the same flow control device 100. Alternatively, the flow control device 100 may be a mass flow controller, a flow splitter, or any other device that controls the flow of process gases in the processing system. Furthermore, if desired, the valve 1100 may be integrated into the flow control device 100.

[0028] Processes that may be performed in the processing system 100 may include wet cleaning, photolithography, ion implantation, dry etching, atomic layer etching, wet etching, plasma ashing, rapid thermal annealing, furnace annealing, thermal oxidation, chemical vapor deposition, atomic layer deposition, physical vapor deposition, molecular beam epitaxy, laser lift-off, electrochemical deposition, chemical mechanical polishing, wafer testing, or any other process that uses controlled volumes of process gases.

[0029] Figure 2A schematic diagram of an exemplary mass flow controller 101 is shown, which is a device 100 for controlling flow that can be used in a processing system 1000. The mass flow controller 101 has a gas supply of process gas fluidly coupled to an inlet 104. The inlet 104 is fluidly coupled to a proportional valve 120 that can vary the volume of process gas flowing through the proportional valve 120. The proportional valve 120 meters the mass flow of the process gas through the P1 volume 106. The proportional valve 120 can provide proportional control of the process gas such that it does not need to be fully open or closed, but can have intermediate states to allow control of the mass flow of the process gas.

[0030] P1 volume 106 is fluidically coupled to proportional valve 120 and is the sum of all volumes within mass flow controller 101 between proportional valve 120 and flow restrictor 160. Pressure transducer 130 is fluidically coupled to P1 volume 106 to enable measurement of the pressure within P1 volume 106. On / off valve 150 is located between flow restrictor 160 and proportional valve 120 and can be used to completely stop the flow of process gas out of P1 volume 106. Alternatively, flow restrictor 160 can be located between on / off valve 150 and proportional valve 120 in an alternative configuration. Finally, flow restrictor 160 is fluidically coupled to outlet 110 of mass flow controller 101. In the processing system, outlet 110 is fluidically coupled to valve 1100 or directly to process chamber 1300. In this embodiment, flow restrictor 160 is located between on / off valve 150 and outlet 110. In an alternative embodiment, the on / off valve 150 is located between the flow restrictor 160 and the outlet 110. Thus, the arrangement of the on / off valve 150 and the flow restrictor 160 may be reversed.

[0031] Inside the first on / off valve 150 are a valve seat and a closure member. When the apparatus 100 is delivering process gas, the first on / off valve 150 is in the open position, eliminating contact between the valve seat and the closure member. This allows process gas to flow while providing negligible restriction to fluid flow. When the first on / off valve 150 is in the closed position, the closure member and valve seat are spring-biased into contact, preventing process gas from flowing through the first on / off valve 150.

[0032] The flow restrictor 160 is used in conjunction with the proportional valve 120 to meter the flow of the process gas. In most embodiments, the flow restrictor 160 provides a known restriction to the fluid flow. The first characteristic flow restrictor 160 can be selected to have a specific flow resistance in order to deliver a desired range of mass flow rates for a given process gas. The flow restrictor 160 has a greater flow resistance than the passages upstream and downstream of the flow restrictor 160.

[0033] Optionally, the mass flow controller 101 includes one or more P2 pressure transducers downstream of the flow restrictor 160 and the on / off valve 150. The P2 pressure transducer is used to measure the pressure difference across the flow restrictor 160. In some embodiments, the P2 pressure downstream of the flow restrictor 160 can be obtained from another device 100 connected to the process chamber, and the reading is transmitted to the mass flow controller 101.

[0034] Optionally, temperature sensors may be employed to further improve the accuracy of the mass flow controller 101. They may be mounted in the base of the mass flow controller 101 near the P1 volume 106. Additional temperature sensors may be used in various locations, including the proportional valve 120, the pressure transducer 130, and the on / off valve 150.

[0035] Go to Figure 3 , shows a schematic diagram of an on / off valve 150, wherein a first embodiment of a flow restrictor 160 is positioned within an outlet passage 157 of the on / off valve 150. The on / off valve 150 has an inlet passage 158 that allows process gas to flow into the valve 150. A spring 156 biases a closing member 154 into contact with the valve seat 152, thereby preventing the flow of process gas when the valve 150 is in the closed state. When in the open state, the closing member 154 is moved to separate from the valve seat 152, thereby allowing the process gas to pass through the valve seat 152 into the outlet 157. The outlet 157 is formed as a cylindrical hole, but can also be formed in an elliptical, polygonal, or any other shape. The flow restrictor 160 is inserted into the outlet 157, and a seal 170 prevents the flow of gas between the flow restrictor 160 and the wall 159 of the outlet 157.

[0036] Steering Figure 4-7 , the flow restrictor 160 and seal 170 are shown in greater detail. Figure 4 A perspective view of a flow restrictor 160 and a seal 170 is shown. The flow restrictor 160 extends along a longitudinal axis AA from a first end 161 to a second end 162. The seal 170 is assembled to the flow restrictor 160. The seal 170 circumferentially surrounds the flow restrictor 160 and has an outer surface 171. The seal 170 extends along a longitudinal axis BB between a first end 172 and a second end 173. The longitudinal axis BB of the seal 170 is collinear with the longitudinal axis AA of the flow restrictor 160. However, in alternative embodiments, the longitudinal axis BB of the seal 170 may not be collinear with the longitudinal axis AA of the flow restrictor 170. In some embodiments, the longitudinal axis BB of the seal is angled relative to the longitudinal axis AA of the flow restrictor 160. In other embodiments, the longitudinal axis BB of the seal may be spaced apart from but parallel to the longitudinal axis AA of the flow restrictor 160. In yet another embodiment, the axes may be both angled and spaced apart from each other.

[0037] like Figure 5 As best shown, flow restrictor 160 has a sealing portion 163 and an unsealed portion 166. Unsealed portion 166 has a first diameter D1 and sealing portion 163 has a second diameter D2, with first diameter D1 being greater than second diameter D2. Seal 170 also includes an inner surface 174 that is in surface contact with sealing portion 163 of flow restrictor 160. Outer surface 171 has a third diameter D3 that is greater than either first diameter D1 or second diameter D2. This creates an interference fit between wall 159 and outer surface 171 and ensures that seal 170 seals against wall 159 of outlet 157 while preventing contact between flow restrictor 160 and wall 159. Inner surface 174 defines a bore through which flow restrictor 160 is received and through which all gas flows generally along axis BB from first end 161 to second end 162 of flow restrictor 160. In yet other embodiments, sealing portion 163 extends the entire length of flow restrictor 160. In yet another embodiment, the first diameter D1 can be the same as the second diameter D2. Preferably, the third diameter D3 has an interference fit with the wall 159. The third diameter D3 can also be the same as the second diameter D2. In addition, the gas does not need to enter the flow restrictor at the first end 161 and exit the flow restrictor at the second end 162, but can also enter through the periphery of the flow restrictor 160. The gas flow within the flow restrictor 160 does not need to flow strictly along the axis BB, but can only flow through the flow restrictor 160 and through the seal 170 rather than around it.

[0038] The sealing portion 163 has a seal-receiving surface 165 and a plurality of ridges 164 that improve the seal and hold it in place. The second diameter D2 is reduced compared to the first diameter D1 to provide space for the seal 170 and enhance its retention on the flow restrictor 160. The ridges 164 have a triangular cross-section and surround the flow restrictor 160. When the seal 170 is installed on the sealing portion 163 of the flow restrictor 160, the ridges 164 deform the seal 170, further enhancing its retention. This ensures that the seal 170 remains in place when the flow restrictor is pressed into the outlet 157. The third diameter D3 generally provides an interference fit with the outlet 157, so depending on the degree of interference, considerable force may be required to press the seal 170 into the outlet 157. In the exemplary embodiment, the sealing portion 163 has two ridges 164. In alternative embodiments, the sealing portion 163 may have larger or smaller ridges 164. The cross-sectional profile of the ridge 164 can be rectangular, trapezoidal, or any other shape. In a further variation, a texture can be formed on the seal receiving surface 165. Such a texture can be formed by knurling, grinding, or any other known process. In an alternative embodiment, a single model of flow restrictor 160 can be installed in multiple outlets 157 having different diameters by modifying the thickness of the seal so that the third diameter D3 is modified to have a suitable interference with the wall 159 of each outlet. This configuration advantageously allows the flow restrictor to be mounted directly on the valve seat, greatly reducing the volume enclosed between the valve seat and the flow restrictor 160. In addition, a variety of valve geometries, hole sizes, and fitting geometries can be accommodated by positioning the flow restrictor 160 within the outlet 157.

[0039] In use, process gas flows through the flow restrictor 160 from the first end 161 to the second end 162. The seal 170 provides a tight fit with the walls of the flow restrictor 160 and the outlet 159 to prevent the process gas from flowing around the flow restrictor 160. Although some gas leakage may occur, when helium is used as the process gas, such leakage is reduced to at least 1×10 Λ This leak rate ensures that a negligible volume of process gas flows around the flow restrictor 160 rather than through it.

[0040] The seal 170 is preferably formed of a non-metallic material such as a plastic material. An exemplary material may be polytetrafluoroethylene (also known as "PTFE" or "Teflon"). Alternative materials may include metals, ceramics, or composite materials. The seal 170 is preferably shrunk or stretched onto the flow restrictor 160 to ensure a tight fit between the seal receiving surface 165 and the inner surface 174. However, other methods may also be considered. In a further embodiment, the seal may be welded, bonded, or pressed onto the flow restrictor 160 to achieve a secure, airtight connection between the seal 170 and the flow restrictor 160. In yet another embodiment, a plurality of identical flow restrictors 160 are mounted to different seals 170 to allow installation into outlets 157 of different sizes.

[0041] Steering Figure 8-14 , shows a second embodiment of a flow restrictor 260 having a seal 270. As shown in Figure 8 As can be seen from the schematic diagram of FIG, a valve 150 is shown. The valve 150 is connected to Figure 3 The valve 150 is substantially the same as the valve 150 of FIG. However, instead of pressing the flow restrictor into the outlet 157, a seal 270 is installed between the sealing surface 153 of the valve 150 and the sealing surface 291 of the base 290. The base 290 includes a flow channel 292, which connects the on / off valve 150 to various components of the mass flow controller 101 or other device 100 for controlling flow. The seal 270 is installed between the sealing surface 153 and the sealing surface 291 and has a first sealing ring 271 and a second sealing ring 272, as shown in FIG. Figure 9 and Figure 10 2. A first sealing ring 271 and a second sealing ring 272 are mounted to a gasket 273 and extend beyond the gasket 273 to engage the sealing recesses 155, 295 of the valve 150 and the base 290, respectively. A plurality of holes 274 extend through the gasket 273 to allow passage of fasteners used to connect the valve 150 to the base 290. Additional holes 275 may be used to facilitate manufacture of the seal 270 or for other purposes, such as sealing additional flow passages.

[0042] like Figure 10 As shown, the first sealing ring 271 of the sealing member 270 receives the flow restrictor 260. The flow restrictor 260 extends from the first end 261 to the second end 262 along the longitudinal axis AA. Figure 10 and 11As shown, the first sealing ring 271 has a first side 276 and a second side 277 opposite the first side 276. A longitudinal axis BB extends through the first sealing ring 271 perpendicular to the first and second sides 276 and 277. The first and second sides 276 and 277 engage the sealing recesses 155 and 295 and are compressed therebetween when the valve 150 is mounted to the base 290. The first sealing ring 271 also has a generally cylindrical inner surface 278 and a sealing web 279 extending through the inner surface 278. A flow aperture 280 is formed in the sealing web 279 to receive the flow restrictor 260. In this embodiment, the flow aperture 280 has a generally rectangular shape, but in other embodiments, it may be circular, oval, or any other shape suitable for accommodating a corresponding flow restrictor. The flow restrictor 260 has a generally rectangular profile along the longitudinal axis and fits snugly within the flow aperture 280. Once the flow restrictor 260 is installed in the flow orifice 280, it can be welded, glued, or press-fitted to achieve a gas-tight seal between the outer surface of the flow restrictor 260 and the sealing web 279, ensuring that no process gas escapes past the flow restrictor 260 without passing through the flow restrictor 260. The first sealing ring 271 also has an outer surface 285, which can be of any size or diameter as long as the first sealing ring 271 can be nested within the sealing recess 155, 295. In alternative configurations, the sealing recess 155, 295 can be omitted. In other configurations, the inner surface 278 and the outer surface 285 do not need to be cylindrical and can be rectangular, elliptical, polygonal, or any other shape.

[0043] Second sealing ring 272 also has a first side 281 and a second side 282. However, second sealing ring 272 differs from first sealing ring 271 in that it lacks a corresponding sealing web. Instead, inner surface 283 defines a flow channel that allows process gas to pass through without significant flow resistance. Ideally, the flow channel and second sealing ring 272 do not restrict fluid flow. In alternative embodiments, seal 270 may include only first sealing ring 271 without second sealing ring 272 or any other components. Alternatively, there may be more than one first sealing ring 271 or second sealing ring 272.

[0044] In alternative embodiments, the flow aperture 280 of the first sealing ring 271 can be circular, rectangular, have a polygonal shape, may include an arc, or may have any known shape. Thus, a flow restrictor of any cross-section can be accommodated in the sealing ring 271. In yet other embodiments, the sealing ring 271 can be press-fit, welded, bonded, or otherwise secured directly within a flow channel such as the outlet 157 of the valve 150 or the flow channel 292 of the base 290. In further embodiments, the gasket 273 can be omitted so that the seal consists solely of the sealing ring 271. The seal 270 is preferably at least partially constructed of a metal material. In the most preferred embodiment, the first sealing ring 271 and the second sealing ring 272 are metal.

[0045] During assembly, seal 270 is placed between valve 150 and base 290 and aligned so that first and second sealing rings 271, 272 are aligned with sealing recesses 155, 295. Flow restrictor 260 then extends into outlet 157 and corresponding flow channel 292 in base 290. Flow restrictor 260 can be attached to first sealing ring 271 so that the seal is located halfway along the length of flow restrictor 260, or it can be attached at any point along the length of flow restrictor 260. It can even be attached substantially flush with first end 261 or second end 262. Furthermore, seal 270 can be installed so that it is located within a portion of valve 150 to minimize the distance between valve seat 152 and flow restrictor 260, thereby minimizing the volume between them. As previously described, seal 270 can also be configured so that flow restrictor 260 is positioned upstream of valve seat 152 and in inlet 158 ​​rather than outlet 157. The seal of this embodiment can reliably produce a helium leak rate better than 1x10 Λ The 11 atm-cc / sec seal essentially eliminates all process gas flow around the flow restrictor 260 .

[0046] Although the present invention has been described with respect to specific examples, including presently preferred modes for carrying out the invention, those skilled in the art will appreciate that there are many variations and permutations of the above-described systems and techniques. It should be understood that other embodiments may be utilized, and structural and functional modifications may be made without departing from the scope of the present invention. Therefore, the spirit and scope of the present invention should be broadly construed in accordance with the appended claims.

Claims

1. A valve assembly comprising: A valve including a channel; A flow restrictor, the flow restrictor comprising: First end; Second end; a longitudinal axis extending from the first end to the second end; a sealing portion located along the longitudinal axis between the first end and the second end; and a seal member in contact with the sealing portion of the flow restrictor and the passage of the valve; The process gas flows from the first end to the second end through the flow restrictor, and the seal prevents the process gas from flowing around the flow restrictor; the flow restrictor is spaced apart from a wall of the channel.

2. The valve assembly according to claim 1, wherein The seal is formed from polytetrafluoroethylene.

3. The valve assembly according to claim 1, wherein The seal is non-metallic.

4. The valve assembly according to claim 1, wherein The seal is metallic.

5. The valve assembly according to claim 1, wherein The seal extends along the longitudinal axis from a first end to a second end.

6. The valve assembly according to claim 1, wherein The flow restrictor further includes a ridge, the seal being in contact with the ridge.

7. The valve assembly according to claim 1, wherein The flow restrictor also includes an unsealed portion having a first diameter and a sealed portion having a second diameter.

8. The valve assembly according to claim 7, wherein: The first diameter is greater than the second diameter.

9. The valve assembly according to claim 7, wherein: The outer surface of the seal has a third diameter that is greater than the first diameter and the second diameter.

10. The valve assembly according to claim 1, wherein The passage of the valve has an inner surface, and the outer surface of the seal contacts the inner surface of the passage of the valve.

11. The valve assembly according to claim 1, wherein The valve further comprises a valve seat and a closing member.

12. The valve assembly according to claim 11, wherein The flow restrictor is located in the passage, which is the outlet passage of the valve.

13. The valve assembly according to claim 1, wherein The passage of the valve is an outlet passage, and the flow restrictor is located in the outlet passage.

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