GB2635775A

GB2635775A - Particle separator

Info

Publication number: GB2635775A
Application number: GB2318915.2A
Authority: GB
Inventors: Dilip Pitale Rohit; Wang Mikael
Original assignee: Edwards Tech Trading Shanghai Co Ltd
Current assignee: Edwards Tech Trading Shanghai Co Ltd
Priority date: 2023-11-23
Filing date: 2023-12-12
Publication date: 2025-05-28
Also published as: GB202318915D0

Abstract

A pre-pump, sub-atmospheric pressure particle separator 10, comprising: an inlet conduit (20, fig. 1) configured to receive a sub-atmospheric pressure effluent stream from a semiconductor processing tool; and a reverse-flow cyclone (30, fig. 1) having an inlet aperture 32 fluidly coupled with the inlet conduit and located proximate an enlarged end, a particle trap 50 located proximate a narrowing end distal the enlarged end and an outlet located proximate the enlarged end, the inlet conduit comprising a baffle structure 60 located therewithin and configured to direct flow of the effluent stream through the inlet conduit and tangentially into the cyclone. The baffle structure may comprise an open region facilitating flow and a blocked region inhibiting flow. The baffle structure may extend into the cyclone. The particle trap may comprise a closure configured to fluidly isolate said particle trap from said cyclone to facilitate removal of particulates during sub-atmospheric operation.

Description

PARTICLE SEPARATOR

FIELD OF THE INVENTION

The field of the invention relates to a particle separator.

BACKGROUND

Particle separators are known. Such separators are used for removing particles from an effluent stream.

io Although such separators provide for removal of particles from treatment of the effluent stream, they have a number of shortcomings. Accordingly, it is desired to provide an improved particle separator.

SUMMARY

According to a first aspect, there is provided a pre-pump, sub-atmospheric pressure particle separator, comprising: an inlet conduit configured to receive a sub-atmospheric pressure effluent stream from a semiconductor processing tool; and a reverse-flow cyclone having an inlet aperture fluidly coupled with the inlet conduit and located proximate an enlarged end, a particle trap located proximate a narrowing end distal the enlarged end and an outlet located proximate the enlarged end, the inlet conduit comprising a baffle structure located therewithin and configured to direct flow of the effluent stream through the inlet conduit and tangentially into the cyclone. The first aspect recognises that a problem with existing separators is that typically particle separation of sub-atmospheric pressure streams involves using filters or other media traps which can be problematic, particularly for effluent streams from semiconductor processing tools where problematic chemicals may be present and long periods of reliable operation are required.

3o Accordingly, a particle separator is provided. The particle separator may be a sub-atmospheric pressure particle separator. The particle separator may be a pre-pump particle separator. In other words, the particle separator may be -2 - located upstream of a pump. The particle separator may comprise an inlet conduit. The inlet conduit may be configured or adapted to receive or convey a sub-atmospheric pressure effluent stream from a semiconductor processing tool. The particle separator may comprise a cyclone. The cyclone may be a reverse-flow cyclone. The cyclone may have an inlet aperture. The inlet aperture may be fluidly coupled with the inlet conduit. The inlet aperture may be located or positioned proximate, towards, at near or within an enlarged end of the cyclone. A particle trap may be located or positioned proximate, towards, at, near or within a narrowing end of the cyclone. The narrowing end may be distal from or located io away from the enlarged end. The cyclone may comprise an outlet located or positioned proximate, towards, at, near or within the enlarged end. The inlet conduit may comprise a baffle structure or arrangement. The baffle structure may be located within the inlet conduit. The baffle structure may be configured or arranged to direct or convey the flow of the effluent stream through the inlet conduit. The baffle structure may be configured to direct the flow of the effluent stream tangentially or with a tangential component into the cyclone. In this way, particulates within the sub-atmospheric pressure effluent stream may be trapped by the particle trap, thereby enabling efficient separation of particulates from the sub-atmospheric effluent stream, providing for long periods of reliable operation.

The baffle structure may define an open region within the inlet conduit facilitating flow of the effluent stream tangentially into the cyclone and a blocked region inhibiting flow of the effluent stream. Hence, the baffle structure may separate the inlet conduit into a region through which the effluent stream may flow and a region which prevents flow of the effluent stream.

The baffle structure may comprise a flow-directing plate extending generally along an elongate axis of the inlet conduit to direct flow of the effluent stream tangentially into the cyclone. Accordingly, the flow-directing plate may control the 3o flow of the effluent stream to deliver it tangentially or with a tangential flow component into the cyclone. -3 -

The flow-directing plate may be orientated to narrow the open region along the elongate axis of the inlet conduit towards the cyclone to direct flow of the effluent stream tangentially into the cyclone. The narrowing not only helps to direct the flow of the effluent stream into the cyclone, but also helps to increase the speed of the effluent stream entering the cyclone, thereby improving the separation efficiency.

The flow-directing plate may be dimensioned to extend into the cyclone. Accordingly, the plate itself may extend into the cyclone which further helps to io direct the flow of effluent stream already within the cyclone.

The baffle structure may comprise a plug configured to define the blocked region to prevent back flow of the effluent stream from the cyclone into the inlet conduit. This helps to prevent backflow into the inlet conduit and prevent eddies disrupting the circumferential flow within the cyclone.

The inlet conduit may have a circular cross-section and the flow-directing plate may be orientated to present a leading edge as a chord which defines an open segment as the open region. The plug may comprise a segment plate extending across the inlet conduit between the flow-directing plate and an inner surface of the inlet conduit which defines a closed segment as the blocked region.

The cyclone may comprise a cylindrical chamber defining the enlarged end and a conical chamber sharing a common axis defining the narrowing end. The inlet conduit may be positioned to overlap the common axis and the baffle structure may be configured to prevent other than tangential flow of the effluent stream into the cylindrical chamber about the common axis.

The outlet may be provided by an outlet conduit extending from the cylindrical 3o chamber and the baffle structure may be configured to direct flow of the effluent stream tangentially into the cyclone between the cylindrical chamber and the outlet conduit. -4 -

The outlet conduit may be dimensioned to extend into the cylindrical chamber beyond the inlet aperture. This helps to prevent the effluent stream bypassing the conical chamber, improving the particle separation efficiency of the cyclone.

The outlet conduit may have a radially-extending upper support having a circumferential seal and an annular plate surrounding the outlet conduit configured to retain the outlet conduit within the cylindrical chamber and enclose the enlarged end. This helps to simplify the manufacture of the separator, by io assisting in accurately positioning the outlet conduit within the cyclone.

The outlet conduit may have a radially-extending lower support configured to retain the outlet conduit within the cylindrical chamber. This helps to simplify the manufacture of the cyclone, particularly for those cyclones having a high axial length to diameter ratio, which help to remove particulates from the sub-atmospheric pressure effluent stream with a desired removal efficiency.

The inlet conduit and/or the outlet conduit may comprise a flow redirection structure configured to change a direction of flow of the effluent stream.

The flow redirection structure may be configured to provide an orthogonal and/or a reverse in a direction of flow of the effluent stream.

The particle trap may comprise a closure configured to fluidly isolate the particle trap from the cyclone to facilitate removal of particulates during sub-atmospheric operation.

The particle separator may comprise plurality of the particle traps. This may assist in facilitating continuous operation by enabling one particle trap to be 3o isolated for emptying whilst the other one remains operational.

The particle separator may comprise a vacuum pump coupled with the outlet. -5 -

The inlet conduit may comprise a foreline couplable with the semiconductor processing tool.

The foreline, reverse-flow cyclone and the vacuum pump may be fluidly connected in series.

The diameter of the cylindrical chamber may be around 1.2 to 1.4 times the diameter of the inlet conduit.

The height of the conical chamber may be around 2 to 2.25 times the diameter of the inlet conduit.

The height of the cylindrical chamber may be around 1.3 to 1.5 times the diameter of the inlet conduit.

The outlet conduit may be positioned to extend by around 1.15 times the diameter of the inlet conduit into the cylindrical chamber. In other words, the outlet may be positioned at around 1.15 times the diameter of the inlet conduit into the cylindrical chamber.

Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function. -6 -

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of a particle separator according to one embodiment; FIG. 2 is a cross-sectional view of the particle separator of FIG. 1; FIG. 3 is a perspective view of the reverse-flow cyclone in more detail; FIG. 4 is a partial cross-sectional view of the reverse-flow cyclone shown in FIG. 3; FIG. 5 illustrates an arrangement for fixing the first cylindrical portion within the io cylindrical chamber; and FIG. 6 shows an arrangement whereby a pair of particle traps are provided at the narrowing end of the conical chamber.

DESCRIPTION OF THE EMBODIMENTS

Before discussing the embodiments in any more detail, first an overview will be provided. Some embodiments provide a particle separator assembly for removing particles from an effluent stream of a semiconductor processing tool. The particle separator arrangement typically comprises a coupling for coupling with a foreline of a semiconductor processing tool, a cyclone and a vacuum pump for drawing the effluent stream from the semiconductor processing tool through the foreline and coupling, through the cyclone and into the vacuum pump. The cyclone provides for simple, typically continuous, mechanical separation of particles from the effluent stream without the need for additional chemicals which may risk adverse reactions or filters or substrates which may become blocked.

The couplings are configured to couple with conventional vacuum couplings and the configuration of the cyclone, together with a baffle structure on the cyclone inlet helps to improve the effectiveness of particle separation at sub-atmospheric pressures.

3o FIG. 1 is a perspective view of a particle separator 10 according to one embodiment. FIG. 2 is a cross-sectional view of the particle separator 10 of FIG. 1. The particle separator 10 is a sub-atmospheric pressure particle separator -7 -which sits upstream of a vacuum pump (not shown). The particle separator 10 has an inlet conduit 20 which receives an effluent stream from a foreline of a semiconductor processing tool (not shown) coupled with a downstream reverse-flow cyclone 30. The reverse-flow cyclone 30 couples with a particle trap (not shown) and a downstream outlet conduit 40. The outlet conduit 40 couples with the vacuum pump.

The inlet conduit 20 has an inlet aperture 22 which is circular in cross-section and is formed with a 90° elbow bend 24. Downstream of the elbow bend 24 is an io elongate cylindrical conduit 26 which couples with a downstream inlet aperture 32 of the reverse-flow cyclone 30.

The reverse-flow cyclone 30 comprises a cylindrical chamber 34 coupled at one end with a conical chamber 36. The conical chamber 36 narrows away from the cylindrical chamber 34 and terminates with a particle trap assembly 50. The cylindrical chamber is enclosed at its other end by an annular plate 38 which receives a first cylindrical portion 42 of the outlet conduit 40.

Downstream of the first cylindrical portion 42 is a U-bend portion 44 of the outlet conduit 40. Downstream of the U-bend portion 44 is a second cylindrical portion 46. The outlet conduit 40 has an inlet aperture 48 which is positioned within the cylindrical chamber 34. The first cylindrical portion 42 is concentrically located within the cylindrical chamber 34. The first cylindrical portion 42 extends axially within the cylindrical chamber 34 to extend beyond the inlet aperture 32. This positions the inlet aperture 48 towards the conical chamber 36, below the inlet aperture 32.

Although in this embodiment an elbow bend 24 and a U-bend portion 44 are provided, it will be appreciated that these items may be omitted or changed if the 3o positioning of the foreline with which the inlet conduit 20 is to be coupled and an inlet of a downstream vacuum pump to which the outlet conduit 40 is to be coupled are orientated or positioned in different locations. -8 -

The diameter B of the cylindrical chamber 34 is typically around 1.2 to 1.4 times the diameter A of the inlet conduit 20. The height C of the conical chamber 36 is typically around 2 to 2.25 times the diameter A of the inlet conduit 20. The height D of the cylindrical chamber 34 is typically around 1.3 to 1.5 times the diameter A of the inlet conduit 20. The outlet conduit 40 is typically may be positioned to extend into the cylindrical chamber 34 a distance E of around 1.15 times the diameter A of the inlet conduit 20. In other words, the outlet 48 is typically positioned at around 1.15 times the diameter A of the inlet conduit 20 into the cylindrical chamber 34.

FIG. 3 is a perspective view of the reverse-flow cyclone 30 in more detail. FIG. 4 is a partial cross-sectional view of the reverse-flow cyclone 30 shown in FIG. 3. As can be seen, the centreline of the inlet aperture 32 is not centred to align with the centreline of the reverse-flow cyclone 30 but is instead offset to one side. A baffle structure is provided comprising a flow-directing plate 60 and a segment plate 62. The flow-directing plate 60 extends from within the cylindrical chamber 34 through the inlet aperture 32 and into the cylindrical conduit 26. The flow-directing plate 60 extends fully between opposing surfaces of the inlet conduit 20, defining in cross-section a cord. Rather than being axially aligned with the centreline of the inlet conduit 20, the flow-directing plate 60 is angularly offset (non-parallel to the axis of the inlet conduit 20) so that the cross-sectional area of the space within which the effluent stream flows reduces towards the reverse-flow cyclone 30. In other words, the flow-directing plate 60 is positioned and orientated to extend generally tangentially into the cylindrical chamber 34. The segment plate 62 defines a segment which blocks the inlet conduit 20 on the enclosed (blind) side of the flow-directing plate 60.

FIG. 5 illustrates an arrangement for fixing the first cylindrical portion 42 within the cylindrical chamber 34. In particular, an annular retainer in the form of a 3o resilient seal 45 is fixed to the outer surface of the first cylindrical portion 42 using a plurality of radially extending stays 47. This enables the first cylindrical portion 42 to be positioned within the cylindrical chamber 34, with the seal 45 being -9 -urged against an inner surface of the cylindrical chamber 34 to retain the first cylindrical portion coaxially within the cylindrical chamber 34 at the required axial position to locate the inlet aperture 48 beyond the inlet aperture 32.

FIG. 6 shows an arrangement whereby a pair of particle traps 52A, 52B are provided at the narrowing end of the conical chamber 36. Each particle trap 52A, 52B is separately actuatable to enable one particle trap to be emptied whilst the other is still in use.

In operation, a vacuum pump (not shown) coupled with an outlet aperture 49 of the outlet conduit 40 draws an effluent stream from a foreline (not shown) of a semiconductor processing tool via the inlet aperture 22. The effluent stream has suspended particulates which are desired to be removed. The effluent stream flows through the elbow bend 20 into the cylindrical conduit 26. The flow-directing plate 60 defines a narrowing void within the inlet conduit 20 through which the effluent stream flows. The narrowing towards the reverse-flow cyclone 30 causes the speed of the effluent stream to increase. The orientation and positioning of the flow-directing plate 60 causes the effluent stream to enter the cylindrical chamber 34 generally tangentially. This causes the effluent stream to flow circumferentially around the cylindrical chamber 34. The presence of the segment plate 62 in combination with the flow-directing plate 60 helps to maintain a generally circumferential flow of the effluent stream within the cylindrical chamber 34. The effluent stream continues to flow into the conical chamber 36 and particulates within the effluent stream fall out of the effluent stream and travel towards the particle trap assembly 50 at the narrowing end of the conical chamber 36. The effluent stream absent the particulates flows into the inlet aperture 48 and through the outlet conduit 40 to the vacuum pump. When operating with the arrangement shown in FIG. 5, one of the particle traps 52A is activated to enable particulate matter to be removed while the vacuum pump 3o remains operational, and vice-versa, allowing uninterrupted operation of the particle separator.

-10 -Most of the chemical reaction by-products in the semiconductor chamber are inhaled as powder or particulates in the dry vacuum pump. The difference between vacuum range and temperature makes the physical properties of byproducts change instantaneously. These powder deposits can cause a series of problems such as pump sticking or stopping, increase in energy consumption, etc. In particular, a large amount of by-product powder can be produced during processing and accumulation of the powder leads to a pressure drop. This leads to shorter pump life during harsh processing. Pump failure leads to backstream flow to tool. However, because the inside physical environment of the pump and chamber can be difficult to change, this make this makes the powder problematic and a filter device desirable to reduce powder in the dry pump. The main aim is therefore to improve or extend the pump lifetime by trapping the powder before the pump. Hence, some embodiments provide a device configured to be installed before the dry pump, which will improve the lifetime of the dry pump by separating powder or other particulates before the dry pump from the process gas or effluent stream. The design of the device promotes the gas into the device and causes cyclone rotation to separate powder from process gas. This approach helps to improve pump lifetime for harsh semiconductor processes. It also helps to address the process backflow from the pump and helps to reduce steady load or avalanche of powder on the pump. In particular, some embodiments provide a metal pipe with an internal baffle designed to swirl the incoming gas, and the inside gas cyclone will expel powder with the centrifugal force. This cyclone trap operates through physical treatment which will not change the chemical structure of the effluent stream resulting in reduced risk.

Particulates fall naturally by gravity and are collected by a container below. Since the cyclone trap is installed before of the dry pump, pressure loss should be considered. However, through simulation calculation, the pressure drop is only 7.72 pa when inlet gas is 5slm.

3o Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

REFERENCE SIGNS

Particle separator 10 Inlet conduit 20 Inlet aperture 22 Elbow bend 24 Cylindrical conduit 26 Reverse-flow cyclone 30 Inlet aperture 32 io Cylindrical chamber 34 Conical chamber 36 Annular plate 38 Outlet conduit 40 First cylindrical portion 42 U-bend portion 44 Seal 45 Second cylindrical portion 46 Stays 47 Inlet aperture 48 Outlet aperture 49 Particle trap assembly 50 Particle traps 52a, 52b Flow-directing plate 60 Segment plate 62

Claims

-13 -CLAIMS1. A pre-pump, sub-atmospheric pressure particle separator, comprising: an inlet conduit configured to receive a sub-atmospheric pressure effluent 5 stream from a semiconductor processing tool; and a reverse-flow cyclone having an inlet aperture fluidly coupled with said inlet conduit and located proximate an enlarged end, a particle trap located proximate a narrowing end distal said enlarged end and an outlet located proximate said enlarged end, said inlet conduit comprising a baffle structure io located therewithin and configured to direct flow of said effluent stream through said inlet conduit and tangentially into said cyclone.
2. The particle separator of claim 1, wherein said baffle structure defines an open region within said inlet conduit facilitating flow of said effluent stream tangentially into said cyclone and a blocked region inhibiting flow of said effluent stream.
3. The particle separator of claim 1 or 2, wherein said baffle structure comprises a flow-directing plate extending generally along an elongate axis of said inlet conduit to direct flow of said effluent stream tangentially into said cyclone.
4. The particle separator of claim 3, wherein said flow-directing plate is orientated to narrow said open region along said elongate axis of said inlet conduit towards said cyclone to direct flow of said effluent stream tangentially into said cyclone.
5. The particle separator of claim 3 or 4, wherein said flow-directing plate is dimensioned to extend into said cyclone.
-14 - 6. The particle separator of any preceding claim, wherein said baffle structure comprises a plug configured to define said blocked region to prevent back flow of said effluent stream from said cyclone into said inlet conduit.
7. The particle separator of any one of claims 3 to 6, wherein said inlet conduit has a circular cross-section and said flow-directing plate is orientated to present a leading edge as a chord which defines an open segment as said open region and wherein said plug comprises a segment plate extending across said inlet conduit between said flow-directing plate and an inner surface of said inlet io conduit which defines a closed segment as said blocked region.
8. The particle separator of any preceding claim, wherein said cyclone comprises a cylindrical chamber defining said enlarged end and a conical chamber sharing a common axis defining said narrowing end, said inlet conduit is positioned to overlap said common axis and said baffle structure is configured to prevent other than tangential flow of said effluent stream into said cylindrical chamber about said common axis.
9. The particle separator of claim 8, wherein said outlet is provided by an outlet conduit extending from said cylindrical chamber and said baffle structure is configured to direct flow of said effluent stream tangentially into said cyclone between said cylindrical chamber and said outlet conduit.
10. The particle separator of claim 9, wherein said outlet conduit is dimensioned to extend into said cylindrical chamber beyond said inlet aperture.
11. The particle separator of claims 9 or 10, wherein said outlet conduit has a radially-extending upper support having a circumferential seal and an annular plate surrounding said outlet conduit configured to retain said outlet conduit within 3o said cylindrical chamber and enclose said enlarged end.
-15 - 12. The particle separator of any one of claims 9 to 11, wherein said outlet conduit has a radially-extending lower support configured to retain said outlet conduit within said cylindrical chamber.
13. The particle separator of any one of claims 9 to 12, wherein said inlet conduit and/or said outlet conduit comprise a flow redirection structure configured to change a direction of flow of said effluent stream.
14. The particle separator of claim 13, wherein said flow redirection structure io is configured to provide an orthogonal and/or a reverse in a direction of flow of said effluent stream.
15. The particle separator of any preceding claim, wherein said particle trap comprises a closure configured to fluidly isolate said particle trap from said cyclone to facilitate removal of particulates during sub-atmospheric operation.
16. The particle separator of any preceding claim, comprising a plurality of said particle traps.
17. The particle separator of any preceding claim, comprising a vacuum pump coupled with said outlet.
18. The particle separator of any preceding claim, wherein said inlet conduit comprises a foreline couplable with said semiconductor processing tool.
19. The particle separator of claim 18, wherein said foreline, reverse-flow cyclone and said vacuum pump are fluidly connected in series.