Fluid Handling Structure

Abstract

Disclosed herein is a fluid handling structure for an immersion lithography apparatus. The fluid handling structure is configured to confine immersion fluid to a region. The fluid handling structure comprises at least one opening at a boundary of a space configured to supply immersion fluid to the space, an extractor assembly configured to extract immersion fluid from the space, a gas knife system radially outward of the extractor assembly relative to the space, and a chamber upstream of the gas knife system and in fluid communication with the gas knife system. The chamber includes a flow uniformization structure such that gas flow through the flow uniformization structure is uniform.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS)

[0001] This application claims priority to European Patent Application No. 23161009.8 filed March 9, 2023 and European Patent Application No. 23184244.4 filed July 7, 2023, which applications are incorporated herein by reference in their entireties.

[0002] The present invention relates to a fluid handling structure and a lithographic apparatus. [Background technology]

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus can, for example, project a pattern (often referred to as a "design layout" or "design") from a patterning device (e.g. a mask) onto a layer of radiation-sensitive material (resist) provided on the substrate (e.g. a wafer). Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning a radiation beam across the substrate in a given direction (the "scan" direction) while synchronously scanning the substrate parallel to or anti-parallel to this direction.

[0004]

[0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements have continually decreased, while the amount of functional elements, such as transistors, per device has steadily increased for decades, following a trend colloquially known as "Moore's Law." To keep up with Moore's Law, the semiconductor industry pursues technologies that enable the creation of smaller and smaller features. To project a pattern onto a substrate, a lithography apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm.

[0005]

[0005] Further improvement in resolution of smaller features can be achieved by providing an immersion fluid with a relatively high refractive index, such as water, over the substrate during exposure. The effect of the immersion fluid is to allow imaging of smaller features, since the exposure radiation will have a shorter wavelength in the fluid than in a gas. The effect of the immersion fluid can also be thought of as increasing the effective numerical aperture (NA) of the system and increasing the depth of focus.

[0006]

[0006] A fluid handling system enables immersion fluid to be confined to a localized area called the immersion space between a liquid confinement structure of a lithographic apparatus and a substrate. The fluid handling system may be an assembly including multiple component parts, some of which have complex and intricate structures. In particular, the fluid handling system provides a complex system of flow channels for fluid to be provided to the immersion space.

[0007]

[0007] The performance of a fluid handling system can be sensitive to the uniformity of fluid flow. It may be desirable to influence the flow path of a fluid to achieve a desired pressure and flow of the fluid downstream of the point of influence. The ability to influence the flow may depend on the dimensions of the structures that define the flow channel. Such dimensions may be limited by manufacturing constraints, such as tolerance, time, and cost issues for manufacturing smaller structures. Summary of the Invention

[0008] It is an object of the present invention to provide a fluid handling structure and a lithographic apparatus comprising the fluid handling structure that improves fluid flow characteristics while maintaining acceptable manufacturing times and costs.

[0009] According to a first aspect of the present invention, there is provided a fluid handling structure for an immersion lithography apparatus. The fluid handling structure is configured to confine immersion fluid to a region. The fluid handling structure has at least one opening at a boundary of a space configured to supply immersion fluid to the space, an extractor assembly configured to extract immersion fluid from the space, a gas knife system radially outward of the extractor assembly relative to the space, and a chamber upstream of the gas knife system and in fluid communication with the gas knife system. The chamber includes a flow uniformization structure such that gas flow through the flow uniformization structure is uniform.

[0010] According to a second aspect of the present invention, there is provided a lithographic apparatus comprising a fluid handling structure.

[0011] Further embodiments, features, and advantages of the present invention, as well as the structure and operation of the various embodiments, features and advantages of the present invention, are described in detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0012]

[0012] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0013] [Figure 1]

[0013] A schematic overview of a lithographic apparatus is shown. [Figures 2a-2d]

[0014] Two different versions of a fluid handling system are shown in cross section, with different features on the left and right sides of each version that may extend around the circumference. [Figure 3]

[0015] Figure 2 depicts a plan view of a fluid handling structure; [Figure 4]

[0016] Figure 1 depicts a side, partial cross-sectional view of a fluid handling structure having a continuous slit; [Figure 5]

[0017] FIG. 1 depicts a side partial cross-sectional view of a flow space of a fluid handling structure having a plurality of discrete slits; [Figure 6a-6b]

[0018] 6 shows two different versions of the fluid handling structure of FIG. 5 having different patterns of slits; [Figures 7a-7c]

[0019] 1 shows three different fluid handling structures providing a plurality of pillars with different configurations; [Figure 8a]

[0020] Figure 7c shows a partial cross-sectional side view of a flow space of the fluid handling structure; [Figure 8b]

[0020] Figure 7c shows a partial, plan view of a flow space and pillars of the fluid handling structure; [Figure 9]

[0021] Figure 1 depicts a side, partial cross-sectional view of a fluid handling structure having a restriction structure; [Figure 10]

[0022] Figure 1 depicts a side, partial cross-sectional view of a fluid handling structure having a continuous slit with a restriction structure; [Figure 11a]

[0023] 10 shows a cross-sectional view AA of the exemplary restriction structure of FIG. 9, the restriction structure including a plurality of circular cross-section tubes with a porous material filled inside the tubes. [Figure 11b]

[0024] 10 illustrates an AA cross section of the exemplary restraint structure of FIG. 9, where the restraint structure includes a plurality of circular cross section tubes with gaps defined between the tubes and filled with a porous material. [Figure 12a]

[0025] 10 shows a cross-sectional view AA of the exemplary restraint structure of FIG. 9, the restraint structure including a plurality of rectangular cross-section tubes with a porous material filled inside the tubes. [Figure 12b]

[0026] 10 illustrates a cross-sectional view AA of the exemplary restraint structure of FIG. 9, the restraint structure including a plurality of rectangular cross-section tubes with gaps defined therebetween and filled with a porous material. [Figure 13a]

[0027] 10 shows a cross-sectional view AA of the exemplary confinement structure of FIG. 9, which includes a plurality of circular cross-section tubes arranged in a two-dimensional array, with the interior of the tubes filled with a porous material. [Figure 13b]

[0028] 10 illustrates a cross-sectional view AA of the exemplary restriction structure of FIG. 9, the restriction structure including a plurality of circular cross-section tubes arranged in two dimensions with gaps defined between the tubes and filled with a porous material. [Figure 14a]

[0029] 10 shows a cross-sectional view AA of the exemplary confinement structure of FIG. 9, which includes a plurality of circular cross-section tubes arranged in a dense two-dimensional array, with the interior of the tubes filled with a porous material. [Figure 14b]

[0030] 10 illustrates an AA cross-sectional view of the exemplary confinement structure of FIG. 9, the confinement structure including a plurality of circular cross-section tubes arranged in a dense two-dimensional array with gaps defined between the tubes and filled with a porous material.

[0014]

[0031] Features shown in the drawings are not necessarily to scale, and the illustrated size and / or arrangement is not limiting. It will be understood that the drawings include optional features that may not be essential to the invention. Also, not all features of a device may be shown in each drawing, but only some of the components relevant to the description of a particular feature may be shown. DETAILED DESCRIPTION OF THE INVENTION

[0015]

[0032] In this document, the terms "radiation" and "beam" are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (eg, having a wavelength of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm).

[0016]

[0033] The terms "reticle," "mask," or "patterning device," as used herein, may be broadly interpreted to refer to a general-purpose patterning device that can be used to impart a patterned cross-section to an incoming radiation beam, corresponding to the pattern to be created in a target portion of a substrate. The term "light valve" can also be used in this context. Besides the classic mask (transmissive or reflective mask, binary mask, phase-shifting mask, hybrid mask, etc.), examples of other such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0017]

[0034] Figure 1 illustrates a schematic diagram of a lithographic apparatus. The lithographic apparatus includes an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam B (e.g., UV or DUV radiation), a mask support (e.g., mask table) MT constructed to support a patterning device (e.g., mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA according to certain parameters, a substrate support (e.g., substrate table) WT constructed to hold a substrate (e.g., resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate support WT according to certain parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., comprising one or more dies) on the substrate W. A controller 500 controls the operation of the entire apparatus. The controller 500 may be a centralized control system or a system of multiple independent sub-controllers within the various subsystems of the lithographic apparatus.

[0018]

[0035] In operation, the illumination system IL receives a radiation beam B from a radiation source SO, for example via a beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic and / or other types of optical components, or any combination thereof, for directing, shaping and / or controlling the radiation. The illuminator IL may be used to condition the radiation beam B so that it has a desired spatial and angular intensity distribution in its cross-section in the plane of the patterning device MA.

[0019]

[0036] The term "projection system" PS as used herein should be interpreted broadly as encompassing various types of projection systems, including refractive optical systems, catadioptric optical systems, anamorphic optical systems, magnetic optical systems, electromagnetic optical systems, and / or electrostatic optical systems, or any combination thereof, as appropriate to the exposure radiation used and / or other factors such as the use of an immersion liquid or a vacuum. Where the term "projection lens" is used herein, this may be considered as synonymous with the more general term "projection system" PS.

[0020]

[0037] The lithographic apparatus is of a type in which the substrate W may be at least partially covered by an immersion liquid having a relatively high refractive index, e.g. water, so as to fill a space 11 between the projection system PS and the substrate W, which is also referred to as immersion lithography. Further information about immersion techniques can be found in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0021]

[0038] The lithographic apparatus may be of a type that includes two or more substrate supports WT (also referred to as "dual stage"). In such a "multi-stage" machine, the substrate supports WT may be used in parallel, and / or while a substrate W on one substrate support WT is being used to expose a pattern on that substrate W, preparation steps for a subsequent exposure of the substrate W may be performed on a substrate W located on another one of the substrate supports WT.

[0022]

[0039] In addition to the substrate support WT, the lithographic apparatus may include a measurement stage (not shown in the drawings). The measurement stage is arranged to hold a sensor and / or a cleaning device. The sensor may be arranged to measure a property of the projection system PS or a property of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning device may be arranged to clean part of the lithographic apparatus, for example part of the projection system PS or part of the system for providing immersion liquid. The measurement stage may move below the projection system PS when the substrate support WT is spaced from the projection system PS.

[0023]

[0040] In operation, the radiation beam B is incident on the patterning device MA, for example a mask held on the mask support MT, and is patterned by a pattern (design layout) present on the patterning device MA. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. Using the second positioner PW and the position measurement system IF, the substrate support WT can be accurately moved, for example to position different target portions C at focused and aligned positions in the path of the radiation beam B. Similarly, the first positioner PM, and possibly further position sensors (not explicitly shown in FIG. 1 ), can be used to accurately position the patterning device MA with respect to the path of the radiation beam B. The patterning device MA and substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the illustrated substrate alignment marks P1, P2 occupy dedicated target portions, they may also be located in spaces between the target portions. When substrate alignment marks P1, P2 are located between target portions C, they are called scribe-lane alignment marks.

[0024]

[0041] To clarify the present invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes: x, y, and z. Each of the three axes is orthogonal to the other two. Rotation about the x-axis is referred to as Rx rotation. Rotation about the y-axis is referred to as Ry rotation. Rotation about the z-axis is referred to as Rz rotation. The x-axis and y-axis define a horizontal plane, while the z-axis is vertical. The Cartesian coordinate system is not a limitation of the present invention and is used for clarity only. Alternatively, another coordinate system, such as a cylindrical coordinate system, may be used to clarify the present invention. The orientation of the Cartesian coordinate system may be different, for example, the z-axis may have a component along the horizontal plane.

[0025]

[0042] Immersion techniques have been introduced into lithography systems to enable improved resolution of smaller features. In an immersion lithography apparatus, a layer of immersion liquid, having a relatively high refractive index, is interposed in a space 11 between the apparatus's projection system PS (through which a patterned beam is projected towards the substrate W) and the substrate W. The immersion liquid covers at least that portion of the substrate W below the final element of the projection system PS. Thus, at least that portion of the substrate W that is to be exposed is immersed in the immersion liquid.

[0026]

[0043] In commercial immersion lithography, the immersion liquid is water. Typically, the water is highly pure, distilled water, such as ultrapure water (UPW), which is often used in semiconductor manufacturing plants. In immersion systems, the UPW is often purified and may undergo additional processing steps before being supplied to the space 11 as the immersion liquid. In addition to water, other liquids with high refractive indices, for example, hydrocarbons such as fluorocarbons, and / or aqueous solutions, can be used as the immersion liquid. It is also envisioned that other fluids besides liquids will be used in immersion lithography.

[0027]

[0044] In this specification, the description will refer to localized immersion where, in use, immersion liquid is confined to a space 11 between the final element 100 and a surface facing the final element 100. This facing surface is the surface of the substrate W or a surface of the support stage (or substrate support WT) that is coplanar with the surface of the substrate W. (Note that in the following text, references to the surface of the substrate W may additionally or alternatively refer to the surface of the substrate support WT, and vice versa, unless otherwise stated.) A fluid handling structure 12 present between the projection system PS and the substrate support WT is used to confine the immersion liquid to the space 11. The space 11 filled with immersion liquid is smaller than the top surface of the substrate W when viewed from above, and the space 11 remains substantially stationary relative to the projection system PS while the substrate W and substrate support WT move underneath.

[0028]

[0045] Other immersion systems are also envisaged, such as unconfined immersion systems (so-called "all wet" immersion systems) and bath immersion systems. In an unconfined immersion system, the immersion liquid covers more than the surface below the final element 100. The liquid outside the space 11 is present as a thin film of liquid. The liquid may cover the entire surface of the substrate W, or even the substrate W and a substrate support WT that is coplanar with the substrate W. In a bath-type system, the substrate W is fully immersed in a bath of immersion liquid.

[0029]

[0046] The fluid handling structure 12 is a structure that supplies immersion liquid to and removes immersion liquid from the space 11, thereby confining the immersion liquid in the space 11. It includes features that are part of a fluid supply system. The arrangement disclosed in PCT Patent Application Publication No. WO 99 / 49504 is an early fluid handling structure that comprises pipes that supply or remove immersion liquid from the space 11 and that operate in response to relative movement of a stage below the projection system PS. In more recent designs, the fluid handling structure extends along at least part of the boundary of the space 11 between the final element 100 of the projection system PS and the substrate support WT or substrate W, so as to partly define the space 11.

[0030]

[0047] The fluid handling structure 12 may have a range of different functions, each of which may be derived from a corresponding feature that enables the fluid handling structure 12 to achieve that function. The fluid handling structure 12 may be referred to by a number of different terms, each of which refers to a function, such as barrier member, seal member, fluid supply system, fluid removal system, liquid confinement structure, etc.

[0031]

[0048] In an embodiment, an immersion liquid is used as the immersion fluid, in which case the fluid handling structure 12 may be a liquid handling system. In accordance with the above, references in this paragraph to features defined with respect to a fluid may be understood to include features defined with respect to a liquid.

[0032]

[0049] The lithographic apparatus has a projection system PS. During exposure of a substrate W, the projection system PS projects a patterned beam of radiation onto the substrate W. To reach the substrate W, the path of the radiation beam B passes from the projection system PS through immersion liquid confined by a fluid handling structure 12 between the projection system PS and the substrate W. The projection system PS has a lens element at the end of the beam's path, which lens element comes into contact with the immersion liquid. This lens element that comes into contact with the immersion liquid may be referred to as the "final lens element" or "final element". The final element 100 is at least partly surrounded by the fluid handling structure 12. The fluid handling structure 12 may confine immersion liquid below the final element 100 and above a facing surface.

[0033]

[0050] Figures 2a, 2b, 2c and 2d show various features that may be present in variants of a fluid handling system. Unless otherwise stated, a design may share some of the same features as Figures 2a, 2b, 2c and 2d. The features described herein may be selected individually or in combination as shown or as required. Although the figures show different versions of a fluid handling system, with different features shown on the left and right sides, these may extend around the entire circumference. Thus, for example, a fluid handling system may have the same feature extending around the entire circumference. For example, a fluid handling system may only have the feature on the left side of Figure 2a, or the right side of Figure 2a, or the left side of Figure 2b, or the right side of Figure 2b, or the left side of Figure 2c, or the right side of Figure 2c, or the left side of Figure 2d, or the right side of Figure 2d. Alternatively, the fluid handling system may provide any combination of features from these figures at different positions around the circumference. The fluid handling system may include a fluid handling structure 12 as described in the variants below.

[0034]

[0051] Figure 2a shows the fluid handling structure 12 around the underside of the final element 100. The final element 100 has the shape of an inverted frusto-conical shape. The frusto-conical shape has a planar lower surface and a conical surface. The frusto-conical shape protrudes from the plane and has a planar lower surface. The planar lower surface is the optically active part of the underside of the final element 100 through which the radiation beam B can pass. The final element 100 may have a coating 30. The fluid handling structure 12 surrounds at least part of the frusto-conical shape. The fluid handling structure 12 has an inner surface facing the conical surface of the frusto-conical shape. The inner surface and the conical surface may have complementary shapes. The upper surface of the fluid handling structure 12 may be substantially planar. The fluid handling structure 12 may fit snugly against the frusto-conical shape of the final element 100. The underside of the fluid handling structure 12 may be substantially planar and, in use, may be parallel to the facing surface of the substrate support WT and / or substrate W. The underside of the fluid handling structure 12 may therefore be referred to as the surface facing the surface of the substrate W. The distance between the underside and the facing surface may be in the range 20 to 500 micrometres, desirably in the range 70 to 200 micrometres.

[0035]

[0052] The fluid handling structure 12 extends closer to the facing surfaces of the substrate W and substrate support WT than the final element 100. A space 11 is therefore defined between an inner surface of the fluid handling structure 12, the plane of the frustoconical portion and the facing surface. In use, the space 11 is filled with immersion liquid. The immersion liquid fills at least part of the buffer space between the complementary surfaces between the final element 100 and the fluid handling structure 12, and in an embodiment fills at least part of the space between the complementary inner surface and the conical surface.

[0036]

[0053] Immersion liquid is supplied to the space 11 via openings formed in the surface of the fluid handling structure 12. Immersion liquid may be supplied via supply openings 20 on an inner surface of the fluid handling structure 12. Alternatively or additionally, immersion liquid is supplied from a lower supply opening 23 formed in the lower surface of the fluid handling structure 12. The lower supply opening 23 surrounds the path of the radiation beam B and may be formed by a series of openings in an array or a single slit. Immersion liquid is supplied to fill the space 11 below the projection system PS such that the flow through it is laminar. Furthermore, the supply of immersion liquid from the lower supply opening 23 prevents bubbles from entering the space 11. This supply of immersion liquid may act as a liquid seal.

[0037]

[0054] Immersion liquid can be recovered from recovery openings 21 formed in the inner surface. Recovery of immersion liquid through the recovery openings 21 can be achieved by applying negative pressure, or recovery through the recovery openings 21 can be achieved as a result of the velocity of immersion liquid flow through the space 11, or both. The recovery openings 21 can be located opposite the supply openings 20 in plan view. Additionally or alternatively, immersion liquid can be recovered via overflow recovery 24 located on the top surface of the fluid handling structure 12. The supply openings 20 and recovery openings 21 can swap functions (i.e. reverse liquid flow direction). This allows the flow direction to be changed depending on the relative movement of the fluid handling structure 12 and the substrate W.

[0038]

[0055] Additionally or alternatively, immersion liquid may be recovered from below the fluid handling structure 12 via recovery openings 25 formed in the underside. The recovery openings 25 may function to maintain a meniscus 33 of immersion liquid against the fluid handling structure 12. The meniscus 33 is formed between the fluid handling structure 12 and the facing surface and acts as a boundary between the liquid space and the gaseous external environment. The recovery openings 25 may be a perforated plate capable of recovering immersion liquid in a substantially single-phase flow. The recovery openings in the underside may be a series of fixed openings 32 through which immersion liquid is recovered. The fixed openings 32 may be capable of recovering immersion liquid in a two-phase flow.

[0039]

[0056] Optionally, radially outwardly relative to the inner surface of the fluid handling structure 12 is a gas knife opening 26. Supplying gas at a high velocity through the gas knife opening 26 may promote liquid confinement of the immersion liquid in the space 11. The supplied gas may be humidified and may comprise substantially carbon dioxide. Radially outwardly of the gas knife opening 26 is a gas recovery opening 28 for recovering gas supplied through the gas knife opening 26.

[0040]

[0057] Further openings may be present on the underside of the fluid handling structure 12, i.e. on the surface of the fluid handling structure 12 facing the substrate W, e.g. open to atmosphere, or a gas source, or vacuum. An example of such an optional further opening 50 is shown in dashed lines on the right-hand side of Figure 2a. As shown, the further opening 50 may be a supply or extraction member, and is indicated by a double arrow. For example, if configured as a supply, the further opening 50 may be connected to a liquid supply or a gas supply, as well as to any of the supply members. Alternatively, if configured as an extraction, the further opening 50 may be used to extract a fluid and may be connected to atmosphere or a gas source or vacuum, for example. For example, at least one further opening 50 may be present between the gas knife opening 26 and the gas recovery opening 28, and / or between the fixed opening 32 and the gas knife opening 26.

[0041]

[0058] The two different versions of the fluid handling structure 12, on the left and right of Figure 2a, fix the meniscus 33. The version of the fluid handling structure 12 on the right of Figure 2a can fix the meniscus 33 in a substantially fixed position relative to the final element 100 due to the fixed position of the fixed aperture 32. The version of the fluid handling structure 12 on the left of Figure 2a fixes the meniscus 33 below the collection aperture 25, so that the meniscus 33 can move along the length and / or width of the collection aperture 25. In order to direct the radiation beam B onto the entire surface of the substrate W being exposed, the substrate support WT, which supports the substrate W, is moved relative to the projection system PS. In order to maximise the power of the substrate W exposed by the lithographic apparatus, the substrate support WT (and thus the substrate W) is moved as fast as possible. However, there is a critical relative velocity (often called the critical scan velocity), above which the meniscus 33 between the fluid handling structure 12 and the substrate W becomes unstable. An unstable meniscus 33 increases the risk of losing immersion liquid, for example in the form of one or more droplets. Furthermore, an unstable meniscus 33 increases the risk of gas bubbles being trapped in the immersion liquid, especially if the trapped immersion liquid spills over the edge of the substrate W.

[0042]

[0059] Liquid droplets present on the surface of the substrate W can add thermal loads and be a source of defects. They can evaporate and leave drying stains, they can carry contaminants such as particles while they travel, they can collide with larger volumes of immersion liquid and create gas bubbles within these volumes, and they can evaporate and add thermal loads to the surface on which they are located. If the surface is involved in the positioning of components of the lithographic apparatus relative to the substrate W being imaged, such thermal loads can be a source of distortion and / or positioning errors. Therefore, the formation of liquid droplets on the surface is undesirable. To avoid the formation of such droplets, the speed of the substrate support WT is limited to a critical scan speed at which the meniscus 33 remains stable. This limits the throughput of the lithographic apparatus.

[0043]

[0060] The left-hand side of the fluid handling system in Figure 2a may include a spring 60. The spring 60 may be an adjustable passive spring configured to apply a biasing force to the fluid handling structure 12 in the direction of the substrate W. The spring 60 can thus be used to control the height of the fluid handling structure 12 above the substrate W. Such adjustable passive springs are described in U.S. Patent No. 7,199,874, the entire contents of which are incorporated herein by reference. Other biasing devices, for example using electromagnetic forces, may also be suitable. Although the spring 60 is shown with the left-hand side of Figure 2a, this is optional and it is not essential that it be included with the other features of the left-hand side of Figure 2a. The spring 60 is not shown in any of the other figures, but may be included with other variations of the fluid handling system described with respect to Figures 2a, 2b, 2c or 2d.

[0044]

[0061] Figure 2b shows two different versions, on the left and right side, of the fluid handling structure 12 that allow movement of the meniscus 33 relative to the final element 100. The meniscus 33 can be moved in the direction of the moving substrate W. This reduces the relative speed between the meniscus 33 and the moving substrate W, resulting in an improved stability of the meniscus 33 and a reduced risk of breakage. The meniscus 33 breaks up at an increased speed of the substrate W, allowing the substrate W to move faster below the projection system PS, thereby increasing throughput.

[0045]

[0062] Features shown in Figure 2b that are in common with Figure 2a share the same reference numbers. The fluid handling structure 12 has an inner surface that is complementary to the conical surface of the frustoconical shape. The lower surface of the fluid handling structure 12 is closer to the facing surface than the lower plane of the frustoconical shape.

[0046]

[0063] Immersion liquid is supplied to the space 11 through supply openings 34 formed in the inner surface of the fluid handling structure 12. The supply openings 34 are located near a lower part of the inner surface, possibly below the lower surface of the frusto-conical shape. The supply openings 34 are located around the inner surface and spaced around the path of the radiation beam B.

[0047]

[0064] Immersion liquid is recovered from the space 11 through recovery openings 25 in the underside of the fluid handling structure 12. When a facing surface moves below the fluid handling structure 12, a meniscus 33 can move at the surface of the recovery opening 25 in the same direction as the movement of the facing surface. The recovery openings 25 may be formed of a porous member. The immersion liquid may be recovered in a single phase. The immersion liquid may be recovered in a two-phase flow. The two-phase flow is received in a chamber 35 in the fluid handling structure 12 where it is separated into liquid and gas. The liquid and gas are recovered from the chamber 35 via separate channels 36, 38.

[0048]

[0065] An inner periphery 39 of the underside of the fluid handling structure 12 extends into the space 11 away from the inner surface to form a plate 40. The inner periphery 39 forms a small opening which can be sized to match the shape and size of the radiation beam B. The plate 40 may act to isolate the immersion liquid on either side. Dispensed immersion liquid flows inward towards the opening, passes through the inner opening and then flows radially outwards beneath the plate 40 towards the surrounding recovery openings 25.

[0049]

[0066] As shown on the right hand side of Figure 2b, the fluid handling structure 12 may be in two parts: an inner part 12a and an outer part 12b. The inner part 12a and the outer part 12b may move relative to each other mainly in a plane parallel to their facing surfaces. The inner part 12a may have a supply opening 34 and may have an overflow collection 24. The outer part 12b may have a plate 40 and a collection opening 25. The inner part 12a may have an intermediate collection 42 for collecting immersion liquid flowing between the inner part 12a and the outer part 12b.

[0050]

[0067] The two different versions of the fluid handling structure in Figure 2b therefore allow the meniscus 33 to move in the same direction as the substrate W, achieving higher scanning speeds and improved throughput of the lithographic apparatus. However, the speed of movement of the meniscus 33 at the surface of the recovery openings 25 of the fluid handling structure 12 on the left side of Figure 2b may be slow. The fluid handling structure 12 on the right side of Figure 2b allows faster movement of the meniscus 33 by moving the outer part 12b relative to the inner part 12a and the final element 100. However, it may be difficult to control the intermediate recovery 42 to ensure that enough immersion liquid is provided between the inner part 12a and the outer part 12b to prevent contact between them.

[0051]

[0068] Figure 2c shows two different left and right side versions of the fluid handling structure 12 that may be used to pin a meniscus 33 of immersion liquid in the fluid handling structure 12 as described above in relation to Figures 2a and / or 2b. Features shown in Figure 2c that are in common with Figures 2a and / or 2b share the same reference numbers.

[0052]

[0069] The fluid handling structure 12 has an inner surface that is complementary to the conical surface of the frustoconical shape. The lower surface of the fluid handling structure 12 is closer to the facing surface than the lower plane of the frustoconical shape. Immersion liquid is delivered via openings formed in the surface of the fluid handling structure 12 and supplied to the space 11. The immersion liquid may be supplied via supply openings 34 in the inner surface of the fluid structure 12. Alternatively or additionally, the immersion liquid may be supplied via supply openings 20 in the inner surface of the fluid structure 12. Alternatively or additionally, the immersion liquid may be supplied via lower supply openings 23. The immersion liquid may be recovered via an extraction member, for example via recovery openings 21 formed in the inner surface, and / or via an overflow 24, and / or via one or more openings in the surface of the fluid handling structure 12 as described below.

[0053]

[0070] Two different versions of the fluid handling structure 12, on the left and right of Figure 2c, pin the meniscus 33. The version of the fluid handling structure 12 on the right of Figure 2c may pin the meniscus 33 in a substantially fixed position relative to the final element 100 due to the fixed position of the recovery opening 32a. The version of the fluid handling structure 12 on the left of Figure 2c may pin the meniscus 33 below the recovery opening 25 so that the meniscus 33 may move along the length and / or width of the recovery opening 25.

[0054]

[0071] As described above with respect to Figure 2b, the inner periphery of the underside of the fluid handling structure 12 extends into the space 11 away from the inner surface to form a plate 40, as shown on the left. As described above, this forms small openings to isolate the immersion liquid on either side and / or to allow the immersion liquid to flow inward towards the opening, through the inner opening and then radially outward beneath the plate 40 towards the surrounding recovery openings 25. This feature is shown on the left side of Figure 2c, but is optionally combined with other features as shown. Preferably, as shown on the left side, immersion liquid is supplied to the space 11 via supply openings 34 formed in the inner surface of the fluid handling structure 12. The supply openings 34 are located near the bottom of the inner surface, possibly below the frusto-conical lower surface. The supply openings 34 are located all around the inner surface and are spaced around the path of the radiation beam B. Alternatively or additionally, immersion liquid may be supplied via supply openings 20 in the inner surface of the fluid structure 12. Alternatively or additionally, immersion liquid may be supplied via lower supply openings 23. Supply openings 34 are the preferred liquid supply, although any combination of supply openings 34, supply openings 20 and / or lower supply openings 23 may be provided.

[0055]

[0072] As shown on the left side of Figure 2c, the fluid handling system may include a fluid handling structure 12 as described above and another device 3000. The fluid handling structure 12 may have an extraction member, such as a recovery opening 25, and a liquid supply opening, such as a lower supply opening 23. It will be appreciated that the fluid handling structure 12 may include any of the configurations disclosed in relation to the left side of Figure 2a, the right side of Figure 2a, the left side of Figure 2b, the right side of Figure 2b or the right side of Figure 2c (described below) in combination with another device 3000.

[0056]

[0073] The further device 3000 may also be referred to as a droplet catcher. The further device 3000 is provided to reduce liquid buildup on the surface of the substrate W after the fluid handling structure 12 has moved over the surface. The further device 3000 may include a liquid supply member 3010 and at least one extraction member 3020. The at least one extraction member 3020 may be formed in a shape that surrounds the at least one supply member 3010 in a plan view. The at least one liquid supply member 3010 may be configured to provide another liquid to a space 3110 between at least a part of the further device 3000 and the surface of the substrate W. The further device 3000 may be configured to recover at least some of the liquid via the at least one extraction member 3020. The further device 3000 may be used to incorporate liquid remaining on the surface of the substrate W into the liquid in the space 3110 and then extract the liquid using the further device 3000 to reduce the amount of liquid remaining on the surface of the substrate W.

[0057]

[0074] In Figure 2c the further device 3000 is shown as a device separate from the fluid handling structure 12. The further device 3000 may be positioned adjacent to the fluid handling structure 12. Alternatively, the further device 3000 may be part of the fluid handling structure 12, i.e. integral with the fluid handling structure 12.

[0058]

[0075] Another device 3000 may be configured to provide a liquid to the space 3110 other than the liquid provided by the fluid handling structure 12 .

[0059]

[0076] Additionally or alternatively, the fluid handling structure 12 may have the components shown on the right-hand side of Figure 2c. More particularly, the fluid handling structure 12 may include at least one liquid supply member, two extraction members (e.g. recovery openings 32a and 32b) and two gas supply members (e.g. gas supply openings 27a and 27b) formed on a surface of the fluid handling structure 12. Gas supply opening 27a may be omitted, i.e. is optional. The at least one liquid supply member may be identical to the lower supply opening 23 on the underside of the fluid handling structure 12 described above, or to the supply openings 20 or liquid supply openings 34 formed on an internal surface of the fluid handling structure 12 described with respect to the left-hand side of Figure 2b. The liquid supply members, extraction members and gas supply members may be formed on a surface of the fluid handling structure 12. In particular, these components may be formed on a surface of the fluid handling structure 12 facing the substrate W, i.e. on the underside of the fluid handling structure 12.

[0060]

[0077] At least one of the two extraction members may comprise a porous material 37. The porous material 37 may be provided in an opening, for example the recovery opening 32a, through which the fluid handling structure 12 can extract fluid from below the fluid handling structure 12 and recover immersion liquid in a single-phase flow. The other of the two extraction members, for example the recovery opening 32b, can recover immersion fluid as a two-phase extractor. The porous material 37 does not have to be flush with the underside of the fluid handling structure 12.

[0061]

[0078] In particular, the fluid handling structure 12 may include a liquid supply member (e.g. lower supply opening 23) and may have a first extraction member (e.g. recovery opening 32a) radially outward of the liquid supply member, a first gas supply member (e.g. gas supply opening 27a) radially outward of the first extraction member, a second extraction member (e.g. recovery opening 32b) radially outward of the first gas supply member and a second gas supply member (e.g. gas supply opening 27b) radially outward of the second extraction member. As with Figure 2a, there may be further openings in the lower surface of the fluid handling structure 12, for example open to atmosphere or a gas source or vacuum, as described above (in relation to the fluid handling structure 12).

[0062]

[0079] For example, at least one further opening (not shown) may be provided in the underside of the fluid handling structure 12. The further opening is optional. The further opening may be located between the first extraction member (e.g., recovery opening 32a) and the first gas supply member (e.g., gas supply opening 27a), as described in the arrangements above. Alternatively or additionally, the further opening may be located between the second extraction member (e.g., recovery opening 32b) and the second gas supply member (e.g., gas supply opening 27b), as described in the arrangements above. The further opening may be identical to the further opening 50 described above.

[0063]

[0080] Optionally, the fluid handling structure 12 includes a recess 29. The recess 29 may be provided between the collection openings 32a and 32b, or between the gas supply openings 27a and 32b. The shape of the recess 29 may be uniform around the entire circumference of the fluid handling structure 12, and may optionally include a slope. If a recess 29 is provided between the collection openings 32a and 32b, the gas supply openings 27b may be provided on a slope, as shown in Figure 2c. If a recess 29 is provided between the supply openings 27a and 32b, the gas supply openings 27b may be provided on a slope, or in a part of the underside of the fluid handling structure 12 that is parallel to the surface of the substrate W. Alternatively, the shape of the recess 29 may vary around the circumference of the fluid handling structure 12. The shape of the recess 29 may be varied to change the effect that gas supplied from the gas supply member has on the fluid below the fluid handling structure 12.

[0064]

[0081] Figure 2d shows two different versions of the fluid handling structure 12 in its left and right parts. The fluid handling structure 12 in the left part of Figure 2d has a liquid injection buffer 41a that holds a buffer amount of immersion liquid, and liquid injection holes 41 that supply immersion liquid from the liquid injection buffer to the space 11. Outside the liquid injection holes 41 are inner liquid recovery openings 43 for directing liquid to an inner recovery buffer 43a that is provided with a porous member. Outside the inner liquid recovery openings 43 are provided recesses 29 similar to those described in relation to Figure 2c. On the underside of the fluid handling structure 12 outside the recesses 29 are gas guide grooves 44 into which outer recovery holes 44a open. The outer recovery holes 44a direct a two-phase recovery flow to an outer recovery buffer 44b that is provided with a porous member. The outermost gas seal holes 45 connect the gas seal buffer volume 45a with the space below the fluid handling structure 12 to provide a gas flow containing immersion liquid.

[0065]

[0082] The fluid handling structure 12 on the right hand side of Figure 2d has a liquid supply opening 20 in its inner sloping surface. On the underside of the fluid handling structure 12 are (from the inside to the outside) an extraction opening 25 provided with a porous member 37, a first gas knife opening 26a, a second gas knife opening 26b and a third gas knife opening 26c. Each of these openings opens into a groove in the underside of the fluid handling structure 12 which provides a buffer volume. The outermost part of the fluid handling structure 12 is stepped to provide greater separation between the fluid handling structure 12 and the substrate W.

[0066]

[0083] 2a to 2d show examples of various configurations that can be used as part of a fluid handling system. While the examples given above refer to particular extraction and recovery members, it will be understood that this particular type of extraction and / or recovery member need not be used. In some cases, different terminology is used to indicate the location of the member, but the same functional characteristics can be provided. Examples of extraction members mentioned above include recovery opening 21, overflow recovery 24, recovery opening 25 (possibly including a porous plate and / or chamber 35), gas recovery opening 28, fixed opening 32, recovery opening 32a, recovery opening 32b, and / or intermediate recovery 42. Examples of supply members mentioned above include supply opening 20, lower supply opening 23, gas knife opening 26, gas supply opening 27a, gas supply opening 27b, and / or supply opening 34. In general, extraction members used to extract / recover fluids, liquids, or gases are interchangeable with at least some of the other examples used to extract / recover fluids, liquids, or gases, respectively. Similarly, supply members used to supply a fluid, liquid or gas are interchangeable with at least one of the other examples used to supply a fluid, liquid or gas, respectively. The extraction members may extract / recover a fluid, liquid or gas from a space by connecting it to a negative pressure which draws the fluid, liquid or gas into the extraction member. The supply members may supply a fluid, liquid or gas to a space by connecting it to an associated supply. Figure 3 shows a plan view of a fluid handling structure 12. The fluid handling structure 12 may be a fluid handling structure 12 used in an immersion lithography apparatus as described above. The fluid handling structure 12 has at least one opening at a boundary of the space 11 configured to supply immersion fluid to the space 11, an extractor assembly (not shown) configured to extract immersion fluid from the space 11, and a gas knife system 2 radially outward of the extractor assembly with respect to the space 11. The fluid handling structure 12 further includes a chamber (not shown) upstream of and in fluid communication with the gas knife system 2.

[0067]

[0084] The fluid handling structure 12 is configured to confine immersion fluid to a region or flow space or space 11 so that the fluid can be provided to the gas knife system 2. As shown, for example in Figure 3, the fluid handling structure 12 includes a fluid supply channel 80 having a fluid supply opening through which fluid can enter a chamber of the fluid handling structure 12. The fluid handling structure 12 surrounds the space 11 in the radial centre of the fluid handling structure 12. The fluid handling structure 12 defines a flow space which provides a flow path from the fluid supply channel 80 to the gas knife system 2.

[0068]

[0085] It may be desirable to influence the fluid flow path to achieve a desired pressure and flow of the fluid downstream of the point of influence. In particular, the fluid velocity and pressure may be greater in a region 81 of the chamber at or around the fluid supply channel 80 than in a region 82 of the chamber remote from the fluid supply channel 80. The performance of a fluid handling system may be sensitive to the uniformity of the fluid flow. In particular, it may be desirable to provide a uniform flow velocity through the fluid equalization structure. The pressure of the fluid may be reduced through the fluid equalization structure. Desirably, the pressure drop is substantially uniform in a circumferential direction surrounding the space, particularly surrounding the gas knife system 2.

[0069]

[0086] As shown in Figure 3, the chamber of the fluid handling structure 12 includes a flow uniformisation structure 70. The flow uniformisation structure 70 is configured so that a fluid, such as a gas, flowing through the flow uniformisation structure 70 is uniform. In particular, it may be desirable to configure the fluid handling structure 12 so that the fluid flow, e.g. flow velocity and pressure, is more uniform and / or at a lower pressure in a region 83 that is radially inward of the flow uniformisation structure 70 relative to the space 11 than in regions 81, 82 that are radially outward of the flow uniformisation structure 70.

[0070]

[0087] In other words, the flow uniformity structure 70 may be configured such that the fluid pressure drop relative to the space 11 from a location immediately radially outside the flow uniformity structure 70 to a location immediately radially inside the flow uniformity structure 70 is between 10 mbar and 200 mbar, preferably between 15 mbar and 150 mbar, more preferably between 20 mbar and 120 mbar, and even more preferably between 40 mbar and 100 mbar. In particular, the fluid pressure drop through the flow uniformity structure 70 is desirably generally uniform in the circumferential direction relative to the space 11. In other words, it is desirable that the pressure drop remain within a range of ±20 mbar, preferably ±10 mbar, and more preferably ±5 mbar over at least 270 degrees, and preferably 300 degrees, in the circumferential direction.

[0071]

[0088] Furthermore, the flow uniformity structure 70 is preferably configured such that the volumetric flow rate between the flow uniformity structure 70 and the gas knife system 2 is preferably substantially uniform in a circumferential direction about the space 11. In other words, over at least 270 degrees, preferably 300 degrees, in a circumferential direction, the pressure drop should preferably remain within the range of ±60 NLPM, preferably ±50 NLPM, more preferably ±40 NLPM, even more preferably ±30 NLPM, and even more preferably ±25 NLPM.

[0072]

[0089] The gas knife system 2 comprises at least one gas knife opening 26 radially outward of the extractor assembly relative to the space 11. The gas knife system 2 comprises at least one gas supply opening 22 radially outward of the at least one gas knife opening 26 relative to the space 11. The fluid handling structure 12 desirably comprises a flow restriction upstream of the at least one gas supply opening 22. The flow restriction is desirably configured such that the fluid velocity of the fluid, in particular the gas, exiting the at least one gas knife opening 26 is greater than the fluid exiting the at least one gas supply opening 22. The flow uniformisation structure 70 may comprise a flow restriction. In other words, the flow uniformisation structure 70 is desirably upstream of the at least one gas supply opening 22 and is desirably configured such that the fluid velocity of the fluid, in particular the gas, exiting the at least one gas knife opening 26 is greater than the fluid exiting the at least one gas supply opening 22.

[0073]

[0090] The ability to affect flow may depend on the dimensions of the structures that define the flow channel, which may be limited by manufacturing constraints such as tolerance, time, and cost issues for manufacturing smaller structures.

[0074]

[0091] Figure 4 shows a cross section of a flow path illustrating a side view of an exemplary configuration of a fluid handling structure 12 having at least one opening 51. Via the opening 51, gas is provided along the flow path to the chamber 7 and further to the gas knife opening 26. As shown in the configuration of Figure 4, a flow uniformisation structure 70 is provided radially outward of the gas knife opening 26 with respect to the space 11. In particular, in this example the flow uniformisation structure 70 is provided radially inward of the at least one opening 51 with respect to the space 11 and radially outward of the gas knife opening 26.

[0075]

[0092] Although not shown in Figure 4, additional components may also be present. For example, an extractor assembly is not shown in Figure 4. In particular, one or more additional components may be provided between the fluid handling structure 12 and the space 11. Alternatively or additionally, the fluid handling structure 12 may include more components than are shown in Figure 4. In particular, the fluid handling structure 12 may include one or more components between the gas knife opening 26 and the space 11.

[0076]

[0093] 4, the flow uniformity structure 70 is provided in the chamber 7 radially closer to the at least one opening 51 than the gas knife opening 26 relative to the space 11. In an alternative arrangement, the flow uniformity structure 70 may be provided radially closer to the gas knife opening 26 than the at least one opening 51 relative to the space 11.

[0077]

[0094] The flow uniformity structure 70 is desirably configured to obstruct the flow path of fluid from the at least one opening 51 to the gas knife system 2. As shown, for example in Figure 4, the flow uniformity structure 70 may form a slit in the chamber 7. A slit is a region of the flow path that has a height that is less than the height of the chamber 7 adjacent to the slit. In other words, the fluid handling structure 12 may include a protrusion 121 that protrudes from the ceiling of the chamber 7 to form a region of the chamber 7 where the cross-sectional area of ​​the flow path is reduced. This may result in fluid flow being restricted in the slit below the protrusion 121 compared to other regions of the flow path. In an alternative configuration, the fluid handling structure 12 may include a protrusion that protrudes from the floor of the chamber 7 to form a region of the chamber 7 where the cross-sectional area of ​​the flow path is reduced.

[0078]

[0095] In the configuration of FIG. 4, the height of at least one slit is lower than the height of the chamber 7 immediately upstream of the at least one slit and lower than the height of the chamber 7 immediately downstream of the at least one slit. Similarly, in the configuration of FIG. 4, the height of at least one slit is lower than the height of the chamber 7 immediately radially outside the at least one slit and lower than the height of the chamber 7 immediately radially inside the at least one slit. In the configuration of FIG. 4, the height of at least one slit may be increased by decreasing the thickness of the protrusion 121, or may be decreased by increasing the thickness of the protrusion 121. The height of the slit is preferably 200 microns to 600 microns, more preferably 300 microns to 500 microns, and even more preferably 300 microns to 400 microns.

[0079]

[0096] The (radial) length of the at least one slit is preferably 0.1 mm to 10 mm, more preferably 0.5 mm to 5 mm, even more preferably 0.75 mm to 1.25 mm, and even more preferably 1 mm. Increasing the radial length of the slit may increase the pressure drop of the fluid passing through the slit (from the radially outer side of the slit to the radially inner side of the slit).

[0080]

[0097] The flow uniformity structure 70 may form a single continuous slit, as shown in Figure 3, for example. In the configuration of Figure 3, the single continuous slit completely surrounds the gas knife system 2. In other words, the slit is circumferentially continuous around the gas knife system 2. The slit in Figure 3 is a single continuous slit forming a continuous circle. Alternatively, the slit may be continuous and non-circular, such as being substantially diamond-shaped, square, octagonal or star-shaped.

[0081]

[0098] Instead of a single continuous slit, the flow uniformization structure 71 may comprise a plurality of discrete slits, as shown, for example, in Figure 5 . Figure 5 shows a cross-sectional view of a flow path of an exemplary configuration of the fluid handling structure 12. Figure 5 shows a flow space that is surrounded and defined by the fluid handling structure 12, although this is not shown. In the configuration of Figure 5 , the flow uniformization structure 71 comprises a plurality of slits 710. In other words, the fluid handling structure 12 defines a plurality of slits 710. The fluid handling structure 12 may comprise a plurality of pillars 711. Each of the plurality of pillars 711 may be located at a position between two adjacent slits 710. Each pillar 711 may extend the entire height of the chamber 7. In other words, each pillar 711 may extend from the floor to the ceiling of the chamber 7. In this way, the pillars 711 may be configured to prevent fluid flow between the slits 710. Fluid may thus be guided along the flow path through the plurality of slits 710 and radially inwards towards the gas knife system 2.

[0082]

[0099] The plurality of slits 710 may consist of 50 to 300 slits, preferably 75 to 200 slits, more preferably 80 to 150 slits, and more preferably 100 slits. The plurality of slits 710 is preferably arranged to surround the gas knife system 2 and is configured to guide fluid on the flow path towards the gas knife system 2. The plurality of slits 710 are preferably evenly distributed circumferentially around the gas knife system 2 with respect to the space 11.

[0083]

[0100] Each slit of the plurality of slits 710 preferably extends to direct a fluid flow path radially relative to the space 11. In other words, the longitudinal direction of each slit 710 is preferably radial. Each of the plurality of slits 710 may be configured to direct fluid from a position radially outer of the respective slit 710 to a position radially inner of the respective slit 710.

[0084]

[0101] The height of each of the plurality of slits 710 is preferably 200 microns to 600 microns, more preferably 300 microns to 500 microns, and even more preferably 300 microns to 400 microns. The width of each of the plurality of slits 710 in the circumferential direction (or radial tangential direction) is preferably equal to or greater than the height of the corresponding slit 710. The width of each slit 710 is preferably equal to the distance between adjacent slits 710. In other words, the width of the pillars 711 between adjacent slits 710 can be equal to the width of each slit 710. Alternatively, the width of each pillar 711 may be equal to or less than the width of the slit 710 defined between adjacent pillars 711. The height of each pillar 711 is preferably equal to or greater than the height of the slit 710 adjacent to the pillar 711.

[0085]

[0102] Multiple discrete slits 710 may be advantageous compared to a single continuous slit because the desired flow uniformity can be achieved using multiple slits 710 that are taller than a single continuous slit required to achieve a similar level of flow uniformity. In other words, using multiple discrete slits 710, the desired flow characteristics can be achieved using slits 710 that are taller than would be necessary with a single continuous slit. The increased height may have the advantage that it is more easily achieved using additive manufacturing to fabricate the fluid handling structure 12 that surrounds and defines the slits 710. Furthermore, the increased height of the slits 710 may have the advantage that the desired flow characteristics are more easily achieved as there is less sensitivity to tolerances in the height of the slits 710. In other words, multiple slits 710 can achieve the desired flow characteristics within a greater height tolerance range than a single continuous slit.

[0086]

[0103] The slits of the plurality of slits 710 in the flow uniformisation structure 71 are arranged at discrete locations such that the plurality of slits 710 form a pattern of slits 710 surrounding the gas knife system 2. The pattern of the slits 710 may, for example, form a circular pattern, a diamond pattern, a square pattern or a star pattern. Figures 6a and 6b show plan views of configurations of fluid handling structures 12 having different patterns of the plurality of slits 710. In other words, Figures 6a and 6b show plan views of configurations of fluid handling structures 12 having different arrangements of pillars 711 separating the plurality of slits 710 or channels. Fluid can flow through the plurality of slits 710 or channels and along a flow path to the gas knife system 2.

[0087]

[0104] In the exemplary configuration of Figure 6a, the pattern of slits 710 forms a non-circular pattern, and in particular a substantially rectangular pattern. Alternatively, the non-circular pattern may be any substantially polygonal pattern. In the exemplary configuration of Figure 6b, the pattern of slits 710 forms a substantially circular pattern. Optionally, each slit of the plurality of slits 710 may be equidistant from the radial periphery 17 of the chamber in a radial direction relative to the space 11. For example, as shown in the configuration of Figure 6b, a majority of the slits of the plurality of slits 710 may be closer to the radial periphery 17 of the chamber than the gas knife system 2. Optionally, as shown in the example of Figure 6b, each slit of the plurality of slits 710 may be equidistant from the gas knife system 2 in a radial direction relative to the space 11.

[0088]

[0105] Instead of, or in addition to, including one or more protrusions to form one or more slits, the flow uniformity structures 72, 73, 74 may include a plurality of pillars. The pillars may also be referred to as plates or vanes. The pillars are configured to prevent fluid flow at the location of the pillars. In other words, the pillars are configured to allow fluid to flow around the pillars, thereby defining a fluid flow path. Each pillar of the plurality of pillars is disposed at a discrete location such that the plurality of pillars form a pattern of pillars surrounding the gas knife system 2. The pattern of pillars may form, for example, a circular pattern, a diamond pattern, a square pattern, or a star pattern.

[0089]

[0106] The height of each pillar is preferably equal to the height of the chamber. In other words, each pillar may extend from the floor of the chamber to the ceiling of the chamber. The pillars thus define a plurality of flow channels, each flow channel being provided between adjacent pillars. A flow channel is a region of the chamber through which fluid can flow, for example, from an opening to the gas knife system 2, which is radially inward of the opening relative to the space 11.

[0090]

[0107] As shown, for example in the configurations of Figures 7a-7c, the flow uniformity structures 72, 73, 74 may include multiple rows of pillars 721-723, 731-733, 741-743. The multiple rows of pillars 721-723, 731-733, 741-743 are desirably configured to direct a fluid flow path radially relative to the space 11. Specifically, the multiple rows of pillars 721-723, 731-733, 741-743 may be configured to define channels between the pillars 721-723, 731-733, 741-743. These channels provide a flow path for fluid to flow from a region radially outward of the multiple rows of pillars 721-723, 731-733, 741-743 to a region radially inward of the multiple rows of pillars 721-723, 731-733, 741-743 relative to the space 11.

[0091]

[0108] As shown, for example in the configurations of Figures 7a-7c, the multiple rows of pillars 721-723, 731-733, 741-743 are preferably arranged concentrically. The multiple rows of pillars 721-723, 731-733, 741-743 include outer rows of pillars 721, 731, 741 and inner rows of pillars 723, 733, 743 that are radially inward of the outer rows of pillars 721, 731, 741 with respect to the space 11. In the configurations of Figures 7a-7c, the multiple rows of pillars include a central row of pillars 722, 732, 742 that is radially inward of the outer rows of pillars 721, 731, 741 and radially outward of the inner rows of pillars 723, 733, 743. With this arrangement, fluid flow paths may extend from a radially outer location between adjacent pillars in the outer rows of pillars 721, 731, 741, then between adjacent pillars in the center row of pillars 722, 732, 742, then between adjacent pillars in the inner row of pillars 723, 733, 743. Instead of multiple rows of pillars consisting of three rows of pillars, there may be only two rows of pillars or four or more rows of pillars.

[0092]

[0109] As shown, for example in the configuration of Figures 7a to 7c, two or more of the pillars 721-723, 731-733, 741-743 of the multiple rows may be arranged in a staggered manner. In particular, the pillars 721-723, 731-733, 741-743 of adjacent rows may be offset from each other in the circumferential direction with respect to the space 11. Although not shown in Figures 7a to 7c, additional components may be provided between the fluid handling structure 12 and the space 11. Alternatively or additionally, the fluid handling structure 12 may include more components than are shown in Figures 7a to 7c. In particular, the fluid handling structure 12 may include components between the gas knife system 2 and the space 11.

[0093]

[0110] In the configuration of Figures 7a and 7b, the pillars 732, 742 in the center row are circumferentially offset from the pillars 731, 741 in the outer rows. Additionally, in the configuration of Figures 7a and 7b, the pillars 733, 743 in the inner rows are circumferentially offset from the pillars 732, 742 in the center row. The pillars 731-733, 741-743 in adjacent rows are preferably circumferentially offset from one another to prevent a direct fluid flow path from a radially outer location of the pillar rows 731-733, 741-743 to a radially inner location of the pillar rows 731-733, 741-743. The pillar rows 731-733, 741-743 are preferably configured such that no direct radial paths exist between the pillar rows 731-733, 741-743. In other words, adjacent rows of pillars 731 - 733 , 741 - 743 preferably define a non-radial flow path, more preferably a circumferential flow path, relative to space 11 .

[0094]

[0111] For example, as shown in the configuration of Figure 7a, the pillars in the inner row of pillars 733 can be shorter longitudinally than the pillars in the outer row of pillars 731. In other words, the pillars in the inner row of pillars 733 can be shorter circumferentially relative to the space 11 than the pillars in the outer row of pillars 731. In this configuration, the number of pillars in the inner row of pillars 733 is greater than the number of pillars in the outer row of pillars 731.

[0095]

[0112] Optionally, there may also be a central row of pillars 732, as shown in FIG. 7a. In such a configuration, the pillars of the central row of pillars 732 are desirably shorter (in a longitudinal direction generally aligned circumferentially) than the pillars of the outer rows of pillars 731. Furthermore, the pillars of the central row of pillars 732 are desirably longer (in a longitudinal direction generally aligned circumferentially) than the pillars of the inner rows of pillars 731. The number of pillars of the central row of pillars 732 in the configuration of FIG. 7a is greater than the number of pillars of the outer rows of pillars 731, and the number of pillars of the central row of pillars 732 is less than the number of pillars of the inner rows of pillars 733.

[0096]

[0113] In a preferred configuration, the number of pillars may increase exponentially from the outer row pillars 731 to the center row pillars 732 to the inner row pillars 733. The number of pillars in the center row pillars 732 may be twice the number of pillars in the outer row pillars 731. The number of pillars in the inner row pillars 733 may be twice the number of pillars in the center row pillars 732.

[0097]

[0114] Because the inner row of pillars 733 has a greater number of pillars, there are also a greater number of channels between adjacent pillars in the inner row of pillars 733. A greater number of channels through which fluid can flow means that less fluid flows through each channel than if there were a fewer number of channels. Thus, without having a smaller number of discrete flow channels, the fluid flow can be distributed evenly around the circumference surrounding the gas knife system 2. In this way, flow uniformity can be improved by providing a configuration with a greater number of pillars in the pillar row radially closest to the gas knife system 2 relative to the space 11, rather than in a row one or more rows radially away from the gas knife system 2.

[0098]

[0115] As shown in the configuration of FIG. 7a, the pillars 731-733 may have non-circular cross-sections. Specifically, the pillars of the inner row of pillars 733 may have non-circular cross-sections. The pillars of the inner row 733 are desirably aligned radially toward the center of the space 11. In other words, the pillars of the inner row 733 may extend radially, with a radial length greater than a circumferential (or radially tangential) length. The pillars of the inner row 733 may be aligned such that fluid flowing through openings or channels defined between adjacent pillars of the inner row 733 is aligned radially. In other words, the pillars of the inner row 733 may be configured to direct a flow path radially such that fluid flowing from just radially outside the pillars of the inner row 733 to radially inside the pillars of the inner row 733 is directed to flow radially toward the center of the space 11. In this way, the flow can be aligned in a preferred direction as it is directed towards the gas knife system 2 .

[0099]

[0116] For example, as shown in the configuration of Figure 7b, each of the plurality of pillars 741-743 can have a circular cross-section. In the configuration of Figure 7b, the pillars of the central row of pillars 742 are circumferentially offset from the pillars of the outer row of pillars 741. The pillars of the inner row of pillars 743 are circumferentially offset from the pillars of the central row of pillars 742. The pillars of the inner row of pillars 743 can be circumferentially aligned with the pillars of the outer row of pillars 741.

[0100]

[0117] The number of pillars 741-743 in each row may be equal. Alternatively, the number of pillars 741-743 in each row may increase as the radial distance to the center of the space 11 decreases. In other words, the number of pillars 742 in the central row may be greater than the number of pillars 741 in the outer rows, and / or the number of pillars 743 in the inner rows may be greater than the number of pillars 742 in the central row. For example, the number of pillars 741-743 may increase exponentially from the outer row pillars 741 to the central row pillars 742 to the inner row pillars 743.

[0101]

[0118] For example, as shown in Figure 7b, multiple pillars 741-743 can form a tessellated pattern of pillars. In the configuration of Figure 7b, each of the pillars 741-743 has a circular cross-section. In other configurations, each of the pillars 741-743 can have a non-circular cross-section. For example, each of the pillars 741-743 can have a square, hexagonal, or octagonal cross-section.

[0102]

[0119] In an alternative configuration, the pillars of one or more of the plurality of rows of pillars 741-743 may have a circular cross-section, and the pillars of one or more other of the plurality of rows of pillars 741-743 may have a non-circular cross-section.

[0103]

[0120] As shown in the configurations of Figures 7a and 7c, each pillar 721-723, 731-733 may have a non-circular cross-section. The non-circular shape of the cross-section is preferably rectangular. Alternatively, pillars 721-723, 731-733 may have a cross-section that is trapezoidal, elliptical, or airfoil-shaped, for example.

[0104]

[0121] In alternative embodiments, the pillars of one or more rows of the plurality of rows of pillars 721-723, 731-733 may have a non-circular cross-section and the pillars of one or more other rows of the plurality of rows of pillars 721-723, 731-733 may have a circular cross-section. Further, the pillars of one or more rows of the plurality of rows of pillars 721-723, 731-733 may have a non-circular cross-section of a first shape and the pillars of one or more other rows of the plurality of rows of pillars 721-723, 731-733 may have a non-circular cross-section of a second shape that is different from the first shape.

[0105]

[0122] In another configuration, such as that of Figure 7c, pillars 721-723 may have a non-circular shape that is longer in the longitudinal direction than in the width direction, i.e., pillars 721-723 may have a rectangular cross section that is longer in the longitudinal direction than in the width direction.

[0106]

[0123] Figure 8a shows a cross-sectional side view of a flow path defined by the fluid handling structure 12 of Figure 7c. A plan view of several pillars 721-723 arranged in the pattern of pillars 721-723 of Figures 7c and 8a is provided in Figure 8b. As shown in Figures 7c, 8a and 8b, this configuration comprises an outer row of pillars 721, a central row of pillars 722 and an inner row of pillars 723. The inner row of pillars 723 is the row of pillars nearest to the centre of the space 11 and closest to the gas knife system 2 in the radial direction R of the space 11. The outer row of pillars 721 is the row of pillars furthest from the centre of the space 11 and furthest from the gas knife system 2 in the radial direction of the space 11.

[0107]

[0124] As shown in Figure 8a, a flow path is provided from the chamber 7 to the flow uniformity structure 72 and onto the gas knife system 2. Specifically, a flow path is provided from the flow uniformity structure 72 to the gas supply openings 22 and the gas knife opening 26. The outer row of pillars 721, the central row of pillars 722, and the inner row of pillars 732 are arranged to sequentially influence the path of fluid flowing from a position radially outward of the portion of the chamber 7 shown in Figure 8a to the gas knife system 2. Specifically, the flow path of fluid flowing through the flow uniformity structure 72 is indicated by arrows 91 in Figure 8b. The pillars of the outer row of pillars 721 are arranged such that fluid enters the longitudinal sides of each pillar of the outer row of pillars 721. The fluid is then redirected from the outer row of pillars 721 towards the pillars of the central row of pillars 722. The pillars of the central row of pillars 722 are positioned such that fluid (diverted from the outer row of pillars 721) enters the longitudinal side of each pillar of the central row of pillars 722. The fluid is then diverted from the central row of pillars 722 towards the pillars of the inner row of pillars 723. The pillars of the inner row of pillars 723 are positioned such that fluid (diverted from the central row of pillars 722) enters the longitudinal side of each pillar of the inner row of pillars 723. The fluid is then diverted from the inner row of pillars 721 towards the gas knife system 2, preferably in a radial direction towards the centre of the space 11.

[0108]

[0125] In the configuration of FIG. 7c, similar to the configuration of FIG. 7b, the pillars 723 of the inner row can be configured such that channels defined between adjacent pillars of the inner row direct flow in a radial direction toward the center of the space 11. In the configuration of FIG. 7c, the pillars of the inner row can be arranged such that the longitudinal direction of the pillars 723 is radial with respect to the space 11. The length (longitudinal) of the pillars of the inner row 723 can desirably be shorter than the length of the pillars of the outer row 721 and / or the central row 722. The pillars of the inner row 723 preferably have a length of 0.5 mm to 2 mm, more desirably 0.5 mm to 1.5 mm, and even more desirably 0.7 mm to 1 mm.

[0109]

[0126] Unlike the inner row pillars 723 in the configuration of FIG. 7c, the pillars of the center row pillars 722 are disposed at an angle relative to the radial direction. Specifically, the center row pillars 722 have a longitudinal direction, which is at an angle relative to the radial direction. The pillars of the outer row pillars 721 and the center row pillars 722 can optionally be the same length. The lengths of the pillars of the outer row pillars 721 and the center row pillars 722 are preferably greater than the lengths of the pillars of the inner row pillars 723. The lengths of the pillars of the outer row pillars 721 and the center row pillars 722 are preferably 0.5 mm to 5 mm, more preferably 0.7 mm to 3 mm, and even more preferably 1 mm to 2 mm, e.g., 1.5 mm. The width of the pillars of the outer row pillars 721, the pillars of the central row pillars 722, and the pillars of the inner row pillars 723 is preferably 0.2 mm to 2 mm, more preferably 0.3 mm to 1.5 mm, and even more preferably 0.3 mm to 1 mm, for example 0.4 mm.

[0110]

[0127] As shown in Figures 7c, 8a, and 8b, the pillars 721 in the outer rows are disposed at an angle relative to the radial direction. Specifically, the pillars 721 in the outer rows have a longitudinal direction that is at an angle relative to the radial direction.

[0111]

[0128] The angle relative to the radial direction is preferably 30 to 80 degrees, more preferably 40 to 75 degrees, even more preferably 50 to 70 degrees, and even more preferably 55 to 65 degrees, for example 60 degrees.

[0112]

[0129] One of the outer row pillars 721 and the center row pillars 722 is angled clockwise from the inner radial direction, and the other of the outer row pillars 721 and the center row pillars 722 is angled counterclockwise from the outer radial direction. For example, as shown in Figure 8b, the center row pillars 722 are angled clockwise 822 from the inner radial direction R0, and the outer row pillars 721 are angled counterclockwise 821 from the outer radial direction R1.

[0113]

[0130] 7c, 8a, and 8b, the number of pillars in the outer rows 721 is the same as the number of pillars in the central row 722. The pillars of the outer rows 721 are aligned circumferentially with the pillars of the central row 722, relative to the space 11. In other words, an imaginary line extending radially through a first end (longitudinal) of a pillar in the outer rows 721 also extends through a first end (longitudinal) of a corresponding pillar in the central row 722. An imaginary line extending radially through a second end (longitudinal) of a pillar in the outer rows 721 also extends through a second end (longitudinal) of a corresponding pillar in the central row 722.

[0114]

[0131] In some configurations of the fluid handling structure 12, for example as shown in Figure 9, the flow uniformisation structure 70 includes a restriction structure 75 configured to restrict the flow path of fluid from the at least one opening 51 to the gas knife system 2. The restriction structure 75 is desirably configured to allow some fluid to pass through the restriction structure 75 from the radially outer region to the radially inner region.

[0115]

[0132] The restricting structure 75 may take any form that restricts fluid flow while allowing some fluid to flow through the restricting structure 75 and out at least one opening 51 to the gas knife system 2. As described in more detail below with reference to Figures 9 to 14, the restricting structure 75 may define a series of openings or holes that form voids within the structure to allow fluid flow therethrough. The restricting structure 75 may therefore have a fill ratio of solid structure volume to void volume. The fill ratio may be consistent throughout the restricting structure 75 or may vary across different regions of the restricting structure 75. The fill ratio may be selected according to the use and properties of the fluid. The voids may be arranged in a regular array / pattern or may be random. The voids in the restricting structure 75 may all have the same size and / or shape, or may have different sizes and / or shapes.

[0116]

[0133] The confinement structure 75 can include or consist of a two-dimensional structure, such as a fine mesh. Alternatively, the confinement structure 75 can include or consist of a three-dimensional structure, such as a lattice structure. In some configurations, such as the configurations of FIGS. 11 through 14 described further below, the confinement structure 75 can include a plurality of tubes. The plurality of tubes can be formed of tubes of the same or different sizes and shapes. The plurality of tubes can be arranged in a regular array or an irregular pattern. In some configurations, each of the plurality of tubes can be arranged to extend radially relative to the space 11 to direct the fluid toward the center of the space 11. Alternatively, the tubes can be arranged in different directions, including non-radially, to further confine or direct the fluid in different directions. The confinement structure 75 is optionally formed using additive manufacturing techniques.

[0117]

[0134] In the exemplary arrangement of Figure 9, the limiting structure 75 is continuous and surrounds the gas knife system 2. In other words, the limiting structure 75 in the arrangement of Figure 9 may surround the gas knife system 2 in a similar manner to the slit in the arrangement of Figure 4. The limiting structure 75 may be a single continuous limiting structure 75 that forms a continuous circle around the gas knife system 2 when viewed from above, for example as shown in Figure 3. Alternatively, the limiting structure 75 may be a continuous non-circular structure, for example substantially diamond-shaped, square, octagonal or star-shaped.

[0118]

[0135] 9, the height of the restrictor structure 75 is equal to the height of the chamber 7. In other words, the restrictor structure 75 extends the entire height of the chamber 7. The restrictor structure 75 may extend from the floor to the ceiling of the chamber 7. In this manner, the restrictor structure 75 may be configured to restrict fluid flow from a radially outer region to a radially inner region of the chamber 7.

[0119]

[0136] Figure 10 shows an alternative configuration of the fluid handling structure 12 of Figure 4 in which the restriction structure 75 is located within at least one slit. In other words, the restriction structure 75 in the configuration of Figure 10 is located between the floor of the chamber 7 and a protrusion 121 extending from the ceiling of the chamber 7. In the alternative configuration in which the protrusion extends from the floor of the chamber 7, the restriction structure 75 may be located between the ceiling of the chamber 7 and the protrusion. Thus, fluid flowing from a radially outer region of the flow uniformization structure 70 to a radially inner region of the flow uniformization structure 70 passes through the restriction structure 75, which is located within the slit or flow channel.

[0120]

[0137] 5 and 6, the flow uniformity structure 71 may include a plurality of slits 710. The restriction structure 75 may be disposed in more than one of the plurality of slits 710. In other words, the restriction structure 75 may be disposed in the space between adjacent pillars of the plurality of pillars 711 that define the plurality of slits 710. In other words, the restriction structure 75 desirably fills more than one of the plurality of slits 710. More desirably, the restriction structure 75 may fill all of the plurality of slits 710.

[0121]

[0138] For example, as described above with reference to Figures 6b, 7a-7c, and 8a-8b, the limiting structures 75 may be disposed between adjacent pillars of the plurality of pillars 711, 721-723, 731-733, 741-743. The limiting structures 75 desirably fill the spaces between adjacent pillars of the plurality of pillars 711, 721-723, 731-733, 741-743.

[0122]

[0139] Adjacent pillars of the plurality of pillars 711, 721-723, 731-733, 741-743 may be adjacent substantially circumferentially with respect to the space 11. In other words, the limiting structures 75 may be disposed between adjacent pillars of the same row of pillars 721-723, 731-733, 741-743. For example, the limiting structures 75 may be provided between adjacent pillars of the outer rows of pillars 721, 731, 741 and / or the inner rows of pillars 723, 733, 743 and / or the central row of pillars 722, 732, 742.

[0123]

[0140] Adjacent pillars of the plurality of pillars 721-723, 731-733, 741-743 may be adjacent in a substantially radial direction with respect to the space 11. In other words, the limiting structure 75 may be disposed between adjacent pillars of different rows of the pillars 711, 721-723, 731-733, 741-743. For example, the limiting structure 75 may be disposed between one or more pillars of the pillars 721, 731, 741 of a first row and one or more pillars of the pillars 722, 732, 742 of a second row. The pillars 722, 732, 742 of the second row are disposed radially inward of the pillars 721, 731, 741 of the first row with respect to the space 11. For example, in a configuration including at least three rows of pillars 721-723, 731-733, 741-743, the limiting structure 75 can be positioned between the pillars 721, 731, 741 of the outer rows and the pillars 722, 732, 742 of the central row, and / or the limiting structure 75 can be positioned between the pillars 722, 732, 742 of the central row and the pillars 723, 733, 743 of the inner rows.

[0124]

[0141] The restricting structure 75 preferably comprises a porous member. The porous member may be a structure or material that defines voids or channels through which fluid can pass. The porous member may comprise, for example, a porous material, a mesh structure, or a lattice structure. The porous member may comprise close-packed blocks, e.g., spherical, with gaps between them forming the voids. The porous material may have a regular or irregular structure. A regular structure may be desirable so that the size of the channels / voids formed by the porous member are known and relatively uniform around the space 11.

[0125]

[0142] The restriction structure 75 may be formed of a porous member. For example, the restriction structure 75 may be formed entirely of a porous material. Alternatively, the restriction structure 75 may include a porous material and a solid structure formed of a solid material. The solid material may be a material configured to prevent fluid flow therethrough. For example, the solid structure may lack voids or channels through which fluid can flow, whereas the porous material may provide voids or channels through which fluid can flow on a path from a region radially outer than the flow uniformity structure 70 to a region radially inner than the flow uniformity structure 70 relative to the space 11.

[0126]

[0143] 11a through 14b illustrate an exemplary restriction structure 75 as viewed at cross section AA of FIG. 11a through 14b. Each of the restriction structures 75 illustrated in FIGS. 11a through 14b includes a plurality of tubes 750 through 750b. The axial direction of each of the plurality of tubes 750 through 750b desirably extends in the direction of a fluid flow path from a radially outer region of the flow uniformity structure 70 to a radially inner region of the flow uniformity structure 70 with respect to the space 11. The tubes 750 through 750b may be arranged such that the axial direction, or longitudinal direction, of the tubes 750 through 750b extends substantially radially with respect to the space 11.

[0127]

[0144] In the exemplary restriction structure 75 shown in FIGS. 11a, 12a, 13a, and 14a, a porous member 751-751b is provided within each of the plurality of tubes 750-750b. Specifically, in these examples, the interior of each of the plurality of tubes 750-750b is filled. For example, each of the plurality of tubes 750-750b can be filled with a porous member 751-751b. In a preferred configuration, the interior of one or more of the plurality of tubes 750-750b, preferably all of the tubes 750-750b, can be solid to further restrict fluid flow. This preferred configuration allows fluid to flow only through the gaps between the tubes 750-750b to reach the downstream side of the restriction structure 75. In other words, because the tubes 750-750b are solid, fluid does not pass through the interior of these tubes, further restricting fluid flow. In another configuration, the interior of one or more of the plurality of tubes 750-750b, and optionally the interior of all of the tubes 750-750b, can be empty to form a plurality of unrestricted flow channels through the interior of the tubes 750-750b. In this configuration with hollow tubes, the wall thickness of the tubes 750-750b need only be sufficient to provide a solid region that restricts fluid flow through the restriction structure 75.

[0128]

[0145] The plurality of tubes 750-750b in FIGS. 11a, 12a, 13a, and 14a define gaps 752-752c between adjacent tubes of the plurality of tubes 750-750b within the restriction structure 75. In the exemplary restriction structure 75 shown in FIGS. 11a, 12a, 13a, and 14a, the plurality of gaps 752-752c are empty, forming channels through which fluid can flow. Alternatively, the plurality of gaps 752-752c may be filled. In the exemplary restriction structure 75 shown in FIGS. 11b, 12b, 13b, and 14b, porous members 753-753c are provided in the plurality of gaps between adjacent tubes of the plurality of tubes 750-750b. Specifically, in these examples, the porous members 753-753c fill the plurality of gaps. In a preferred configuration, the interior of one or more, preferably all, of the plurality of gaps can be solid to further restrict fluid flow. This preferred configuration allows fluid to flow only through the interior of the tubes 750-750b to reach the downstream side of the restriction structure 75. In other words, the gaps 752-752c between the tubes 750-750b are solid, and fluid does not pass through these gaps 752-752c, further restricting fluid flow. To merely restrict, but not prevent, fluid flow through the restriction structure 75, at least a portion of the structure must be non-solid. In other words, it is not desirable for both all of the plurality of gaps 752-752c and the interiors of all of the plurality of tubes 750-750b to be solid.

[0129]

[0146] In the configurations shown in FIGS. 11a-11b, 13a-13b, and 14a-14b, each of the plurality of tubes 750-750b has a circular cross-sectional shape. In the configuration of FIG. 12, each of the plurality of tubes 750a has a non-circular cross-sectional shape. Specifically, tube 750a in FIG. 12 has a rectangular cross-sectional shape. Alternatively, tubes 750-750b may have different non-circular shapes, such as oval or hexagonal. In another configuration, the plurality of tubes may include tubes with different cross-sectional shapes. For example, some tubes may have circular cross-sectional shapes and some tubes may have oval cross-sectional shapes.

[0130]

[0147] In each of the configurations shown in Figures 11a to 14b, the plurality of tubes 750-750b are arranged in an array that extends circumferentially relative to the space 11. The array of tubes 750-750b of the flow uniformization structure 70 may form a circle around the gas knife system 2 when viewed from above, for example as shown in Figure 3. Alternatively, the array of tubes 750-750b may be continuous and non-circular, for example substantially diamond-shaped, square, octagonal or star-shaped.

[0131]

[0148] In the configurations of Figures 11a-11b and 12a-12b, the tubes 750, 750a are arranged in a one-dimensional array that extends circumferentially relative to the space 11. In the configurations of Figures 13a-13b and 14a-14b, the array of tubes 750b is a two-dimensional array. The two-dimensional array of tubes 750b in Figures 13a-13b and 14a-14b extends circumferentially relative to the space 11 and also extends heightwise of the chamber 7. Thus, within the same cross-sectional area where there are fewer large tubes 750, 750a in the configurations of Figures 11a-11b and 12a-12b, the configurations of Figures 13a-13b and 14a-14b may include a larger number of smaller tubes 750b.

[0132]

[0149] The two-dimensional array of tubes 750b in Figures 13a-13b and 14a-14b includes multiple rows of tubes 750b, with the tubes 750b in each row extending circumferentially relative to the space 11. In the two-dimensional array of tubes 750b in Figures 13a-13b, the rows of tubes 750b are circumferentially aligned with one another. In other words, the two-dimensional array of tubes 750b in Figures 13a-13b includes vertical columns of tubes 750b. Each vertical column includes multiple tubes 750b arranged directly above one another in the height direction of the chamber 7.

[0133]

[0150] FIGS. 14a-14b illustrate an example in which the tubes 750b in adjacent rows are circumferentially offset from one another. In other words, the array of tubes 750b can be arranged to form a tessellated pattern. In this manner, the size of the gaps 752c between the tubes 750b in different rows can be reduced. Specifically, the total cross-sectional area of ​​the gaps 752c can be reduced compared to the configuration of FIGS. 13a-13b. The array of tubes 750b in FIGS. 14a-14b can be considered a close-packed array. While FIGS. 14a-14b provide an example in which the tubes 750b have circular cross-sections to form a circular close-packed array, alternative configurations may provide non-circular close-packed arrays. For example, the limiting structure 75 can include a hexagonal close-packed array, including multiple tubes 750b, each having a hexagonal cross-sectional shape. The use of hexagonal cross-section tubes 750b is preferred in applications in which smaller gaps 752c between the tubes 750b are desired.

[0134]

[0151] The present invention may provide a lithographic apparatus, which may have any / all of the other features or components of the lithographic apparatus described above, for example, the lithographic apparatus may optionally comprise at least one or more of a fluid handling structure 12, a radiation source SO, an illumination system IL, a projection system PS, a substrate support WT, etc.

[0135]

[0152] In particular, the lithographic apparatus may include a projection system PS configured to project a radiation beam B towards a region of a surface of a substrate W.

[0136]

[0153] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it will be appreciated that the lithographic apparatus described herein may have other applications, including the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0137]

[0154] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, machine-readable media may include read-only memory (ROM), random-access memory (RAM), magnetic storage media, optical storage media, flash memory devices, electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Additionally, firmware, software, routines, and instructions may be described herein as performing particular actions. However, it should be understood that such description is for convenience only, and that such actions actually result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., which, in execution, may cause actuators or other devices to interact with the physical world.

[0138]

[0155] Although specific reference may be made herein to embodiments of the invention in the context of a lithography apparatus, embodiments of the invention may also be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatus may be generally referred to as lithography tools. In such lithography tools, ambient (non-vacuum) conditions may be used.

[0139]

[0156] Although particular reference may have been made above to the use of embodiments of the present invention in the context of optical lithography, it will be understood that the present invention is not limited to optical lithography, where the context permits.

[0140]

[0157] Embodiments include the following numbered clauses: 1. A fluid handling structure for an immersion lithography apparatus configured to confine immersion fluid to a region, the fluid handling structure having at least one opening at a boundary of a space configured to supply immersion fluid to the space, an extractor assembly configured to extract immersion fluid from the space, a gas knife system radially outward of the extractor assembly relative to the space, and a chamber upstream of the gas knife system and in fluid communication with the gas knife system, the chamber including a flow uniformization structure such that gas flowing through the flow uniformization structure is uniform. 2. A fluid handling structure as described in clause 1, wherein the gas knife system includes at least one gas knife opening radially outward of the extractor assembly relative to the space. 3. A fluid handling structure as described in clause 2, wherein the gas knife system includes at least one gas supply opening radially outward of the at least one gas knife opening relative to the space. 4. A fluid handling structure as described in clause 3, further comprising a flow restriction upstream of the at least one gas supply opening such that gas exiting the at least one gas knife opening has a higher gas velocity than gas exiting the at least one gas supply opening. 5. A fluid handling structure according to any of clauses 1 to 4, wherein the flow uniformisation structure is configured to restrict the flow path of fluid from the at least one opening to the gas knife system. 6. A fluid handling structure according to clause 5, wherein the flow uniformisation structure defines at least one slit, the height of the at least one slit being less than the height of the chamber adjacent the at least one slit. 7. A fluid handling structure according to clause 6, wherein the height of the at least one slit is smaller than the height of the chamber immediately upstream of the at least one slit and smaller than the height of the chamber immediately downstream of the at least one slit. 8. A fluid handling structure according to any of clauses 5 to 7, wherein at least one slit is a single continuous slit and surrounds the gas knife system. 9. The fluid handling structure of any of clauses 5 to 7, wherein the at least one slit comprises a plurality of slits. 10. A fluid handling structure according to clause 9, wherein each slit of the plurality of slits extends to direct a fluid flow path radially relative to the space. 11. A fluid handling structure according to clause 9 or 10, wherein each slit of the plurality of slits is arranged at a discrete location such that the plurality of slits form a pattern of slits surrounding the gas knife system. 12. A fluid handling structure according to clause 11, wherein the pattern of slits forms a circular pattern or a square pattern or a star pattern. 13. A fluid handling structure according to any of clauses 9 to 12, wherein each slit of the plurality of slits is equidistant from the gas knife system in a radial direction relative to the space. 14. The fluid handling structure of any of clauses 9 to 12, wherein each slit of the plurality of slits is equidistant from the radial periphery of the chamber in a radial direction relative to the space. 15. A fluid handling structure according to any of clauses 9 to 14, wherein a majority of the plurality of slits are closer to the radial periphery of the chamber than the gas knife system. 16. A fluid handling structure according to any of clauses 1 to 15, wherein the flow uniformisation structure is configured to obstruct the flow path of fluid from the at least one opening to the gas knife system. 17. A fluid handling structure according to clause 16, wherein the flow uniformisation structure comprises a plurality of pillars, each pillar having a height equal to the height of the chamber. 18. A fluid handling structure according to clause 17, wherein the plurality of pillars comprises a plurality of rows of pillars. 19. A fluid handling structure according to clause 18, wherein the plurality of rows of pillars directs a fluid flow path radially relative to the space. 20. A fluid handling structure according to clause 18 or 19, wherein the plurality of rows of pillars are arranged concentrically. 21. A fluid handling structure according to any of clauses 18 to 20, wherein the pillars of the plurality of rows are arranged in a staggered manner such that the pillars of adjacent rows are offset from one another in a circumferential direction relative to the space. 22. A fluid handling structure according to any of clauses 18 to 21, wherein the plurality of rows of pillars comprises an outer row of pillars and an inner row of pillars radially inward of the outer row of pillars relative to the space, and the plurality of rows of pillars comprises a central row of pillars radially inward of the outer row of pillars and radially outward of the inner row of pillars. 23. A fluid handling structure as claimed in clause 22, wherein the pillars of the inner rows of pillars are shorter (in the longitudinal direction) than the pillars of the outer rows of pillars. 24. A fluid handling structure according to clause 22 or 23, wherein the number of pillars in the inner rows of pillars is greater than the number of pillars in the outer rows of pillars. 25. A fluid handling structure according to clause 23 or 24, wherein the pillars in the central row of pillars are shorter than the pillars in the outer rows and the pillars in the central row of pillars are longer than the pillars in the inner rows. 26. A fluid handling structure according to any of clauses 22 to 25, wherein the number of pillars in the central row of pillars is greater than the number of pillars in the outer rows of pillars and the number of pillars in the central row of pillars is less than the number of pillars in the inner rows of pillars. 27. A fluid handling structure according to clause 26, wherein the number of pillars increases exponentially from the outer rows of pillars to the central row of pillars to the inner rows of pillars. 28. A fluid handling structure according to any of clauses 24 to 27, wherein the pillars of the inner row are aligned radially towards the centre of the space so that fluid flowing through openings defined by the pillars of the inner row is aligned radially. 29. A fluid handling structure according to any of clauses 17 to 28, wherein each pillar has a circular cross section. 30. A fluid handling structure according to any of clauses 17 to 28, wherein each pillar has a non-circular cross-section (preferably a rectangular, elliptical or airfoil-shaped cross-section). 31. A fluid handling structure according to clause 30 when dependent on any of clauses 22 to 28, wherein the pillars of the central row are arranged at an angle to a radial direction towards the centre of the space. 32. A fluid handling structure according to clause 31, wherein the pillars of the central row have a longitudinal direction, the longitudinal direction being at the aforesaid angle relative to a radial direction towards the centre of the space. 33. A fluid handling structure according to any of clauses 30 to 32, wherein the pillars of the outer rows are arranged at an angle to a radial direction towards the centre of the space. 34. A fluid handling structure according to clause 33, wherein the pillars of the outer rows have a longitudinal direction, the longitudinal direction being at an angle as described above relative to a radial direction towards the centre of the space. 35. A fluid handling structure according to clause 34, wherein the angle relative to the radial direction is between 30 and 80 degrees. 36. A fluid handling structure as described in clause 35, wherein one of the outer row pillars and the central row pillars is at the aforesaid angle in a clockwise direction from the radial direction, and the other of the outer row pillars and the central row pillars is at the aforesaid angle in a counterclockwise direction from the radial direction. 37. A fluid handling structure according to any of clauses 33 to 36, wherein the number of pillars in the outer rows of pillars is the same as the number of pillars in the central row of pillars. 38. A fluid handling structure according to clause 37, wherein the pillars of the outer rows of pillars are aligned circumferentially with respect to the space with the pillars of the central row of pillars. 39. A fluid handling structure according to any one of clauses 5 to 38, wherein the flow uniformisation structure includes a restriction structure configured to restrict a flow path of fluid flowing from the at least one opening to the gas knife system. 40. A fluid handling structure as described in clause 39, wherein the restrictive structure is continuous and surrounds the gas knife system. 41. The fluid handling structure of clause 39 or 40, wherein the height of the restriction structure is equal to the height of the chamber. 42. A fluid handling structure according to clause 39 when dependent on any one of clauses 6 to 15, wherein the restriction structure is located within at least one slit. 43. A fluid handling structure according to clause 42, wherein the restriction structure fills at least one slit. 44. The fluid handling structure of clause 42 or 43, wherein the at least one slit includes all the slits of the plurality of slits. 45. A fluid handling structure according to clause 39 when dependent on any one of clauses 17 to 38, wherein the restriction structure is located between adjacent pillars of the plurality of pillars. 46. ​​A fluid handling structure according to clause 45, wherein the restriction structure fills a space between adjacent pillars of the plurality of pillars. 47. A fluid handling structure according to clause 45 or 46, wherein adjacent pillars of the plurality of pillars are circumferentially adjacent to the space. 48. A fluid handling structure according to any one of clauses 45 to 47, wherein adjacent pillars of the plurality of pillars are adjacent in a radial direction relative to the space. 49. A fluid handling structure according to any one of clauses 39 to 48, wherein the restriction structure comprises a porous member. 50. The porous member is a porous material, or Mesh structure, or 49. The fluid handling structure of claim 49, comprising a lattice structure. 51. A fluid handling structure according to clause 49 or 50, wherein the restriction structure is formed from a porous member. 52. A fluid handling structure according to any one of clauses 39 to 50, wherein the restriction structure comprises a plurality of tubes, the axial directions of the tubes extending substantially radially relative to the space. 53. A fluid handling structure according to clause 52 when dependent on clause 49 or 50, wherein a porous member is provided inside each of the plurality of tubes. 54. A fluid handling structure according to clause 53, wherein the porous member fills the interior of each of the plurality of tubes. 55. A fluid handling structure according to clause 52, wherein the interior of each of the plurality of tubes is solid. 56. A fluid handling structure according to any one of clauses 52 to 55, wherein each of the plurality of tubes has a non-circular cross-sectional shape. 57. A fluid handling structure according to any one of clauses 52 to 56, wherein the plurality of tubes are arranged in an array extending circumferentially about the space. 58. A fluid handling structure according to clause 57, wherein the array of a plurality of tubes is a two-dimensional array. 59. A fluid handling structure according to any one of clauses 52 to 58, wherein the plurality of tubes define a plurality of gaps between adjacent tubes within the restrictive structure. 60. A fluid handling structure according to clause 59, wherein the porous member is provided in a plurality of gaps. 61. A fluid handling structure according to clause 60, wherein the porous member fills a plurality of gaps. 62. A fluid handling structure according to clause 59, wherein the solid material fills a plurality of gaps. 63. A lithographic apparatus comprising a fluid handling structure according to any of clauses 1 to 62. 64. A method of manufacturing a fluid handling structure according to any of clauses 1 to 63, comprising additive manufacturing.

[0141]

[0158] While specific embodiments of the present invention have been described above, it will be understood that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not limiting. Thus, it will be apparent to those skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims that follow.

Claims

1. 1. A fluid handling structure for an immersion lithographic apparatus configured to confine immersion fluid to a region, the fluid handling structure comprising: at least one opening configured to supply the immersion fluid to the space; an extractor assembly configured to extract the immersion fluid from the space; a gas knife system radially outward of the extractor assembly relative to the space; a chamber upstream of the gas knife system and in fluid communication with the gas knife system; The fluid handling structure, wherein the chamber includes a flow uniformity structure such that gas flowing through the flow uniformity structure is uniform.

2. the gas knife system includes at least one gas knife opening radially outward of the extractor assembly relative to the space; Desirably, the gas knife system includes at least one gas supply opening radially outward of the at least one gas knife opening relative to the space; 2. The fluid handling structure of claim 1, further comprising a flow restriction upstream of the at least one gas supply opening, desirably such that gas exiting the at least one gas knife opening has a higher gas velocity than gas exiting the at least one gas supply opening.

3. the flow uniformity structure is configured to restrict a flow path of fluid from the at least one opening to the gas knife system; Preferably, the flow uniformity structure defines at least one slit, the height of the at least one slit being less than the height of the chamber adjacent the at least one slit; 3. A fluid handling structure according to claim 1 or 2, desirably the height of the at least one slit is less than the height of the chamber immediately upstream of the at least one slit and less than the height of the chamber immediately downstream of the at least one slit.

4. the at least one slit is a single continuous slit and surrounds the gas knife system, or the at least one slit comprises a plurality of slits; Preferably, each of the plurality of slits extends radially relative to the space to direct a fluid flow path therethrough; Desirably, each slit of the plurality of slits is arranged at a discrete location such that the plurality of slits form a pattern of slits surrounding the gas knife system; The fluid handling structure of claim 3 , wherein the pattern of slits preferably forms a circular pattern or a square pattern or a star pattern.

5. each slit of the plurality of slits being equidistant from the gas knife system in a radial direction relative to the space; or each slit of the plurality of slits being equidistant from a radial outer periphery of the chamber in a radial direction relative to the space; The fluid handling structure of claim 4 , wherein the majority of the plurality of slits are desirably closer to the radial outer periphery of the chamber than the gas knife system.

6. the flow uniformity structure is configured to obstruct a flow path of fluid from the at least one opening to the gas knife system; Preferably, the flow uniformity structure comprises a plurality of pillars, the height of each pillar being equal to the height of the chamber; Preferably, the plurality of pillars includes a plurality of rows of pillars; Preferably, the plurality of rows of pillars direct a fluid flow path radially relative to the space; 6. The fluid handling structure of claim 1, wherein the plurality of rows of pillars are preferably arranged concentrically.

7. the pillars of the plurality of rows are arranged in a staggered pattern such that the pillars of adjacent rows are offset from one another in a circumferential direction with respect to the space, and / or the pillars of the plurality of rows include pillars of an outer row with respect to the space and pillars of an inner row that are radially inward of the pillars of the outer row; the plurality of rows of pillars includes a central row of pillars radially inward of the outer row of pillars and radially outward of the inner row of pillars; Preferably, the pillars of the inner row of pillars are shorter (longitudinally) than the pillars of the outer row of pillars; Preferably, the number of pillars in the inner row of pillars is greater than the number of pillars in the outer row of pillars; Preferably, the pillars of the central row are shorter than the pillars of the outer rows, and the pillars of the central row are longer than the pillars of the inner rows; Preferably, the number of pillars in the central row is greater than the number of pillars in the outer rows, and the number of pillars in the central row is less than the number of pillars in the inner rows; Preferably, the number of pillars increases exponentially from the outer rows of pillars to the central rows of pillars to the inner rows of pillars; 7. The fluid handling structure of claim 6, wherein the inner rows of pillars are desirably aligned in the radial direction towards the centre of the space such that fluid flowing through openings defined by the inner rows of pillars is aligned in the radial direction.

8. each pillar has a circular cross-section, or each pillar has a non-circular cross-section (preferably a rectangular, elliptical, or airfoil-shaped cross-section); Preferably, when dependent on claim 7, the pillars of the central row are arranged at an angle to the radial direction towards the centre of the space; 8. The fluid handling structure of claim 6 or 7, wherein desirably the central row of pillars has a longitudinal direction, said longitudinal direction being at an angle to said radial direction towards the centre of the space.

9. the outer rows of pillars are disposed at an angle relative to the radial direction toward the center of the space; Preferably, the outer rows of pillars have a longitudinal direction, the longitudinal direction being at the angle relative to the radial direction towards the centre of the space; Preferably, the angle relative to the radial direction is between 30 and 80 degrees; Preferably, one of the outer row pillars and the central row pillars is at the angle clockwise from the radial direction, and the other of the outer row pillars and the central row pillars is at the angle counterclockwise from the radial direction; Preferably, the number of pillars in the outer rows is the same as the number of pillars in the central row; The fluid handling structure of claim 8 , wherein desirably the pillars of the outer rows of pillars are aligned circumferentially with the space with the pillars of the central row of pillars.

10. the flow uniformity structure includes a restriction structure configured to restrict a flow path of fluid from the at least one opening to the gas knife system; Preferably, the limiting structure is continuous and surrounds the gas knife system; Preferably, the height of the limiting structure is equal to the height of the chamber; Preferably, when dependent on any of claims 3 to 5, the limiting structure is arranged within the at least one slit; Preferably, the restricting structure fills the at least one slit; Desirably, the at least one slit includes all slits in the plurality of slits.

11. the limiting structure is disposed between adjacent pillars of the plurality of pillars; Preferably, the limiting structure fills a space between adjacent pillars of the plurality of pillars; Preferably, the adjacent pillars among the plurality of pillars are adjacent to each other in a circumferential direction with respect to the space, Preferably, the adjacent pillars among the plurality of pillars are adjacent to each other in a radial direction with respect to the space, Preferably, the limiting structure comprises a porous member; Preferably, the porous member comprises a porous material, a mesh structure, or a lattice structure; The fluid handling structure of claim 10 when dependent on any of claims 6 to 9, preferably wherein the restricting structure is formed from the porous member.

12. the limiting structure includes a plurality of tubes, the axial directions of the tubes extending substantially radially relative to the space; Preferably, when dependent on claim 11, the porous member is provided inside each of the plurality of tubes, Preferably, the porous member fills the interior of each of the plurality of tubes; 12. The fluid handling structure of claim 10 or 11, wherein the interior of each of the plurality of tubes is desirably solid.

13. each of the plurality of tubes has a non-circular cross-sectional shape, and / or the plurality of tubes are arranged in an array extending circumferentially relative to the space; Preferably, the array of the plurality of tubes is a two-dimensional array, and / or the plurality of tubes define a plurality of gaps between adjacent tubes within the confinement structure; Preferably, the porous member is provided within the plurality of gaps; Preferably, the porous member fills the plurality of gaps; The fluid handling structure of claim 12, wherein a solid material desirably fills the gaps.

14. A lithographic apparatus comprising a fluid handling structure according to any preceding claim.

15. A method of manufacturing a fluid handling structure according to any preceding claim, comprising additive manufacturing.

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