Remote plasma source isolation valve

Abstract

Techniques described herein relate to a design for a remote plasma source isolation valve with improved performance and extended life. Embodiments include a isolation valve comprising a valve body defining a flow passage between an upstream interface and a downstream interface, a closure member coupled to the valve body and movable between an open position permitting flow through the passage and a closed position obstructing the passage, and a sealing element disposed on a fixed wall of the valve body surrounding a port of the passage and recessed from a region of the passage traversed by flow when the closure member is in the open position, wherein the sealing element is arranged to engage the closure member in the closed position to fluidly isolate the upstream interface from the downstream interface.

Description

PATENTAttorney Docket No.: 44025891 WO01REMOTE PLASMA SOURCE ISOLATION VALVE BACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to a design for a remote plasma source isolation valve with improved performance and extended life.Description of the Related Art

[0002] Isolation valves typically refer to flow-control devices commonly installed between an upstream gas or plasma source and a downstream process volume, such as a semiconductor processing chamber, to selectively permit or block the passage of process gases and to isolate one region from another during operation, purge, maintenance, leak checking, or fault conditions. In such environments, the process stream may include chemically aggressive species (e.g., halogencontaining gases, oxidizers, and plasma-generated radicals and ions), elevated temperatures, pressure differentials, and high-velocity flow that collectively can accelerate degradation of valve components.

[0003] For example, elastomeric sealing members such as O-rings may undergo chemical attack (e.g., swelling, embrittlement, cracking, and loss of elasticity) and / or mechanical wear (e.g., abrasion, extrusion, and particulate generation) due to repeated cycling and exposure to reactive species, which can compromise sealing integrity. When the seal is compromised, the isolation valve may exhibit increased leak rates, reduced ability to maintain vacuum or pressure setpoints, increased contamination risk, and diminished process repeatability, thereby reducing operating capacity and requiring more frequent repair, replacement, and associated tool downtime that is time-intensive and costly.

[0004] Accordingly, there is a need in the art for improved techniques in the design of isolation valves.SUMMARYPATENTAttorney Docket No.: 44025891 WO01

[0005] Embodiments of the present disclosure generally relate to a design for a remote plasma source isolation valve with improved performance and extended life.

[0006] Some embodiments include an isolation remote valve comprising a valve body defining a flow passage between an upstream interface and a downstream interface, a closure member coupled to the valve body and movable between an open position permitting flow through the passage and a closed position obstructing the passage, and a sealing element disposed on a fixed wall of the valve body surrounding a port of the passage and recessed from a region of the passage traversed by flow when the closure member is in the open position, wherein the sealing element is arranged to engage the closure member in the closed position to fluidly isolate the upstream interface from the downstream interface.

[0007] Other embodiments include an isolation valve assembly comprising a valve body defining a flow passage between an upstream plasma source and a downstream chamber, a retractable plunger coupled to the valve body and movable between an open position permitting flow through the passage and a closed position obstructing the passage, and a sealing element disposed on a fixed wall of the valve body surrounding a port of the passage and recessed from a region of the passage traversed by flow when the retractable plunger is in the open position, wherein the sealing element is an O-ring arranged to engage the closure member in the closed position to fluidly isolate the upstream plasma source from the downstream chamber.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of the disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.PATENTAttorney Docket No.: 44025891 WO01

[0009] FIG. 1 is a cross-sectional view of a valve assembly, according to an embodiment described herein.

[0010] FIG. 2 is an additional cross-sectional view of a valve assembly, according to an embodiment described herein.

[0011] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0012] Embodiments of the present disclosure generally relate to a design for a remote plasma source isolation valve with improved performance and extended life.

[0013] In a typical valve assembly, a plunger may be pneumatically retracted, thereby enabling gas flow to a chamber. In existing conventional valves, an O-ring used for sealing may be directly in the flow path of highly reactive plasma generated radical containing gases that can degrade the O-ring within relatively few cycles. Once the seal is compromised, it must be replaced (e.g., requiring the valve to be sent out for refurbishment). In at least one embodiment, the direct exposure of the O-ring to the highly reactive ion species of the plasma gas may be reduced by moving it away from the direct path of the gas. For example, the O-ring may be placed on the wall of the fixed valve body rather than on the movable plunger. Additionally, the O-ring may be recessed, such as by a tenth of an inch, into the wall of the valve body. In this way, only a fraction of the plasma generated radical containing gas flows over the O-ring, reducing the chemical attack and / or mechanical wear experienced by the O-ring. Replacement of the O-ring may be performed far less often, and due to the location of the O-ring on the wall, it may be replaced much more easily and quickly without excessive disassembling and downtime.

[0014] Also in certain embodiments, each component exposed to the plasma generated radical containing gases may be made of aluminum alloy. As such, mechanical wear of the aluminum components may occur as the componentsPATENTAttorney Docket No.: 44025891 WO01move. Grease used to lubricate the components may also leak into the chamber environment, compromising the system. In at least one embodiment, polytetrafluoroethylene (PTFE) sleeves, such as Teflon, may be implemented around one or more aluminum components to reduce the mechanical wear as well as reduce and / or eliminate the grease used to lubricate the aluminum components. Additionally, dual seals may be used to further isolate the actuation area of the valve from the chamber environment and reduce unwanted leaks.

[0015] FIG. 1 depicts a side cross-sectional view of a conventional valve 100 configuration, including a gas flow inlet and outlet points, a plunger, and an O-ring.

[0016] For example, the valve 100 may comprise a valve body 130 having a plunger 120 that regulates the flow of gas through the valve (e.g., plasma flowing from a plasma source to a chamber). The plunger 120, for instance, may be pneumatically actuated (or otherwise configured) to move between an open position, allowing gas flow, and a closed position, obstructing the flow. The valve body 130 may define a flow passage between an upstream inlet and a downstream outlet, facilitating the transfer of the plasma gas. The valve 100 may also include a sealing element, such as an O-ring 110 to engage a sealing surface of the plunger 120 when the plunger 120 is in the closed position to fluidly isolate an upstream region from a downstream region.

[0017] When the plunger 120 is in open position, gas may flow into the valve 100, pass over the O-ring 110, and then exit the valve 100. During that time, the O-ring 110 is susceptible to chemical attack due to the exposure to plasma generated radicals flowing from the inlet port to the outlet port. In addition to chemical degradation (e.g., swelling, embrittlement, cracking, and loss of elasticity), the O-ring 110 may experience mechanical wear (e.g., abrasion, extrusion into gaps, compression set, and particulate generation) due to repeated engagement and disengagement with the plunger 120 and due to high-velocity gas flow, which can further compromise sealing performance. This results in increased leak rates, reduced vacuum or pressure maintenance, and contamination risks, necessitating frequent replacement or refurbishment of the valve. As discussed below with respect to FIG. 2, improved techniques for valve design reduce direct exposure ofPATENTAttorney Docket No.: 44025891 WO01sealing elements to reactive gases and promote enhanced durability and reliability of the system.

[0018] FIG. 2 depicts a side cross-sectional view of an isolation valve 200 configured for use with a remote plasma source.

[0019] The isolation valve 200 may comprise valve bodies 230 and 235, a plunger 240, spring 245, and one or more O-rings 260, 265, and 270. The plunger 240 may be centrally positioned within the valve body 235 and may regulate the flow of plasma gases through the valve 200. For example, the plunger 240 may be actuated pneumatically to move between an open position (as shown in FIG. 2), permitting gas flow, and a closed position, obstructing the gas flow (not shown). The gas may flow from a plasma source 210 to a chamber 220 and may comprise, for instance, a highly reactive ion species of plasma gas. In some embodiments, the spring 245 may be positioned at the rear of the plunger 240 and may be configured to keep the valve in a closed state (e.g., the plunger 240 in a closed position, prohibiting the flow of gas) under default conditions. This ensures that, in the event of pneumatic or power failure, the plunger 240 automatically moves back to and remains in the closed position, sealing the chamber 220 and preventing unintended exposure to the gas.

[0020] The valve bodies 230 and 235 as well as the plunger 240 and any other components exposed to the plasma gas may be constructed with an aluminum alloy in order to withstand the chemically aggressive environment of plasma-generated gases. One or more sleeves 250 may surround a portion of or all of the plunger 204 and / or the spring 245. The sleeves may be made from PTFE (e.g., Teflon), which minimizes friction and mechanical wear between the plunger 240 and the valve body 235. The sleeves 250 may also eliminate the need for grease or other lubricants (e.g., typically used to reduce to mechanical wear of the aluminum components due to repeated actuation cycles), thereby preventing potential contamination of the chamber 220 and maintaining a clean processing environment.

[0021] Sealing elements, such as the O-rings 260 may be arranged around the plunger 240 and / or the spring 245. The O-rings 260 may be made fromPATENTAttorney Docket No.: 44025891 WO01fluoroelastomer (FKM), such as Viton. Certain O-rings 260 may be outside of the sleeves 250 (such as on the front face of the sleeve) or inside the sleeves 250 (such as the dual O-rings around the back side of the plunger 240), as depicted. Additional O-rings may be implemented in the valve 200. For example, a set of two O-rings 265 may be positioned on the plunger 240 (e.g., in a groove). In some embodiments, such as when the sleeves 250 are used, the double O-rings 265 may be situated around the plunger 240, and within the corresponding Teflon sleeve. Dual seal configurations enhance the reliability of the valve 200 by reducing the risk of leaks and preventing migration of contaminants into the chamber 220. For example, in cases when grease is used for lubrication, the O-rings may prevent it from leaking into the chamber 220.

[0022] An O-ring 270 may positioned on the wall of the valve body 230. The O-ring 270 may also be recessed into the wall of the valve body 230 (e.g., in a direction away from the valve body 235). For example, the O-ring 270 may be recessed by a tenth of an inch (i.e., 0.1 inches), though other recess depths are contemplated by this disclosure. The O-ring 270 may be positioned to engage the face of the plunger 240 when the valve 200 is in the closed position, ensuring a durable seal that fluidly isolates the upstream plasma source 210 from the downstream chamber 220. In some embodiments, the area in which the O-ring 270 is positioned by may recessed into the wall of the valve body 230 such that the O-ring 270 is not in the direct path of the plasma gas and the plunger 240 still fits against the O-ring 270 when in the closed position, ensuring a strong seal. An additional O-ring 275 may be postioned on the back face of the plunger 240. Both O-rings 270 and 275 may be made from perfluoroelastomer (FFKM), which provides a higher life expectancy for the seals. When the plunger 240 is in the open position (e.g., after the plunger 240 is retracted using pneumatic force) and the plasma gas is flowing through the valve 200, the recessed O-ring 270 is shielded from direct contact with high-velocity plasma radicals (unlike in conventional designs where the O-ring is exposed directly to the plasma flow), significantly reducing chemical degradation such as swelling, embrittlement, and cracking, as well as mechanical wear like abrasion and extrusion.PATENTAttorney Docket No.: 44025891 WO01

[0023] The combination of using aluminum alloy for all gas-exposed components, Teflon sleeves 250 for reduced mechanical wear, and strategically placed 0-rings results in a valve assembly with extended operational life, improved sealing integrity, and simplified maintenance. For example, the recessed O-ring 270 can be replaced on-site without requiring the entire valve to be sent back to the supplier, minimizing downtime and maintenance costs. This design also allows for higher cycle life and improved process repeatability, addressing the shortcomings of conventional valves.Additional Considerations

[0024] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and / or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are "about" or "approximately" the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0025] Likewise whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising”, it is understood that we also contemplate the same composition or group of elements may be modified with other transitional phrases, such as “consisting essentially of,” “consisting of’, “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa. The phrases, unless otherwise specified, “consists essentially of’ and “consisting essentially of” do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the claimed features, additionally, the phrases do not exclude impurities and variances normally associated with the elements and materials used.

[0026] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departingPATENTAttorney Docket No.: 44025891 WO01from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

PATENTAttorney Docket No.: 44025891 WO01WHAT IS CLAIMED IS:

1. An isolation valve, comprising:a valve body defining a flow passage between an upstream interface and a downstream interface;a closure member coupled to the valve body and movable between an open position permitting flow through the passage and a closed position obstructing the passage; anda sealing element disposed on a fixed wall of the valve body surrounding a port of the passage and recessed from a region of the passage traversed by flow when the closure member is in the open position, wherein the sealing element is arranged to engage the closure member in the closed position to fluidly isolate the upstream interface from the downstream interface.

2. The isolation valve of claim 1 , wherein the sealing element is recessed by 0.1 inches from the region of the passage traversed by flow when the closure member is in the open position.

3. The isolation valve of claim 1 , wherein the sealing element comprises an 0-ring formed of perfluoroelastomer (FFKM).

4. The isolation valve of claim 1 , wherein the closure member comprises a plunger having a face configured to engage the sealing element in the closed position.

5. The isolation valve of claim 4, further comprising a polytetrafluoroethylene (PTFE) sleeve disposed around at least a portion of the plunger.

6. The isolation valve of claim 4, wherein the isolation valve is normally closed by a spring and is opened by pneumatic retraction of the plunger.

7. The isolation valve of claim 4, further comprising an additional 0-ring on a back face of the plunger positioned to shield an actuation side of the isolation valve during flow through the passage.PATENTAttorney Docket No.: 44025891 WO018. The isolation valve of claim 4, further comprising a first seal and a second seal arranged in series around the plunger.

9. The isolation valve of claim 1 , wherein components of the valve body exposed to gas comprise an aluminum alloy.

10. The isolation valve of claim 1 , wherein the upstream interface is configured to couple to a remote plasma source and the downstream interface is configured to couple to a chamber.

11. An isolation valve assembly, comprising:a valve body defining a flow passage between an upstream plasma source and a downstream chamber;a retractable plunger coupled to the valve body and movable between an open position permitting flow through the passage and a closed position obstructing the passage; anda sealing element disposed on a fixed wall of the valve body surrounding a port of the passage and recessed from a region of the passage traversed by flow when the retractable plunger is in the open position, wherein the sealing element is an O-ring arranged to engage the retractable plunger in the closed position to fluidly isolate the upstream plasma source from the downstream chamber.

12. The assembly of claim 11 , wherein the sealing element is recessed by 0.1 inches from the region of the passage traversed by flow when the retractable plunger is in the open position.

13. The assembly of claim 11 , wherein the O-ring is formed of perfluoroelastomer (FFKM).

14. The assembly of claim 11 , wherein the retractable plunger has a face configured to engage the sealing element in the closed position.PATENTAttorney Docket No.: 44025891 WO0115. The assembly of claim 14, further comprising a polytetrafluoroethylene (PTFE) sleeve disposed around at least a portion of the retractable plunger.

16. The assembly of claim 14, wherein the isolation valve is normally closed by a spring and is opened by pneumatic retraction of the retractable plunger.

17. The assembly of claim 14, further comprising an additional O-ring on a back face of the retractable plunger positioned to shield an actuation side of the isolation valve during flow through the passage, where in the additional O-ring is formed of FFKM.

18. The assembly of claim 14, further comprising a first seal and a second seal arranged in series around the retractable plunger.

19. The assembly of claim 11 , wherein components of the valve body exposed to gas comprise an aluminum alloy.

20. The assembly of claim 11 , wherein the isolation valve does not contain a lubricant.

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