Fluid handling system and method capable of reducing defects caused by liquid remaining on a substrate, and lithographic apparatus including such a fluid handling system

Abstract

1. A fluid handling structure for an immersion lithography apparatus, the fluid handling structure comprising: a feature in the bottom surface having a substantially polygonal shape defined by a plurality of sides, the feature being configured to confine immersion liquid in a space between a bottom surface of the fluid handling structure and a surface of a substrate and / or a substrate support supporting the substrate; an opening configured to supply immersion fluid to said space; an extractor configured to extract immersion fluid from said space; and an immersion fluid recovery arrangement outside the feature and adjacent to a side of the feature, the immersion fluid recovery arrangement including an immersion fluid manipulator configured to form an elongated wiper zone extending at an angle to said side of the feature; and an immersion fluid recovery opening for extracting immersion fluid.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to European Application No. 23157818.8, filed February 21, 2023, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a fluid handling structure and a device manufacturing method, and further to a lithographic apparatus including the fluid handling structure. [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, use a projection system to 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 at once, and so-called scanners, in which each target portion is irradiated by scanning a radiation beam across the pattern in a given direction (the "scan" direction) while simultaneously scanning the substrate parallel to or anti-parallel to this direction.

[0004]

[0004] As semiconductor manufacturing processes continue to improve, the dimensions of circuit elements have continued to shrink, while the amount of functional elements, such as transistors, per device has steadily increased for decades, following a trend commonly referred to as "Moore's Law." To keep up with Moore's Law, the semiconductor industry pursues technologies that allow for the creation of smaller and smaller features. To project a pattern onto a substrate, a lithography apparatus can 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 (e.g., water) with a relatively high refractive index onto the substrate during exposure. The immersion fluid has the effect of allowing imaging of smaller features, since the exposure radiation will have a shorter wavelength in such a fluid than in a gas. The effect of the immersion fluid can be thought of as increasing the effective numerical aperture (NA) of the system, as well as increasing the depth of focus.

[0006]

[0006] The immersion fluid can be confined to a localized region between the projection system of the lithographic apparatus and the substrate by the fluid handling structure.

[0007]

[0007] In lithography apparatus that use immersion liquid (often referred to as immersion lithography apparatus), droplets or liquid films left on the substrate can lead to defects. For example, when the meniscus of the immersion liquid filling the immersion space between the projection lens and the substrate collides with droplets left on the substrate, gas (e.g., air) bubbles can enter the immersion liquid and enter the beam path. Gas bubbles in the beam path can cause distortions in the image projected onto the substrate, leading to defects. The droplets or liquid films can also cause dried marks (known as "watermarks") on the resist.

[0008]

[0008] Existing arrangements have proven effective in terms of controlling immersion liquid. However, there is a desire to improve the throughput of lithographic apparatus, i.e., in the case of immersion lithographic apparatus, to increase the speed of relative movement between the substrate and the immersion liquid. Existing fluid handling structures may not be effective at such high speeds. Summary of the Invention

[0009]

[0009] An object of the present invention is to provide a fluid handling system and method that can reduce defects caused by liquid remaining on a substrate even when the relative motion speed of the substrate is high.

[0010]

[0010] According to a first aspect of the present invention, there is provided a fluid handling structure for an immersion lithography apparatus configured to confine immersion liquid in a space between a bottom surface of the fluid handling structure and a substrate and / or a surface of a substrate support supporting the substrate, the structure having a feature in the bottom surface having a substantially polygonal shape defined by a plurality of sides, an opening configured to supply immersion fluid to said space, an extractor configured to extract immersion fluid from said space, and an immersion fluid recovery arrangement outside the feature and adjacent to one side of the feature, the immersion fluid recovery arrangement including an immersion fluid manipulator configured to form an elongated wiper zone extending at an angle to said side of the feature, and an immersion fluid recovery opening for extracting immersion fluid.

[0011]

[0011] According to a second aspect of the present invention, there is provided a lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held by the substrate holder, and the above-mentioned fluid handling structure.

[0012]

[0012] According to a third aspect of the present invention, there is provided a device manufacturing method in a lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held by the substrate holder, and a fluid handling structure as defined in any preceding claim, the method comprising using the fluid handling structure to confine immersion fluid in a space between a surface of the substrate and at least part of the fluid handling structure, and using an immersion fluid recovery arrangement to recover immersion fluid that escapes confinement by the fluid handling structure.

[0013] Further embodiments, features, and advantages of the present invention, as well as the structure and operation of these 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]

[0014]

[0014] Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which like reference symbols indicate corresponding parts, and in which: [Figure 1]

[0015] 1 depicts a schematic overview of a lithographic apparatus; [Figure 2]

[0016] FIG. 1 illustrates a schematic cross-section of a fluid handling structure; [Figure 3]

[0017] FIG. 10 is a schematic cross-section of another fluid handling structure; [Figure 4]

[0018] FIG. 1 is a schematic plan view of a fluid handling system; [Figure 5A]

[0019] 1 illustrates an immersion fluid recovery arrangement according to an embodiment of the present invention. [Figure 5B] 1 illustrates an immersion fluid recovery arrangement according to an embodiment of the present invention; [Figure 5C] 1 illustrates an immersion fluid recovery arrangement according to an embodiment of the present invention; [Figure 5D]1 illustrates an immersion fluid recovery arrangement according to an embodiment of the present invention; [Figure 6]

[0020] FIG. 1 depicts a schematic plan view of a fluid handling system having an immersion fluid recovery arrangement; [Figure 7]

[0021] FIG. 10 shows a schematic plan view of another fluid handling system having an immersion fluid recovery arrangement;

[0015]

[0022] Features shown in the drawings are not necessarily to scale, and the illustrated size and / or arrangement is not limiting. It should be understood that the drawings include optional features, which 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 relevant components may be shown to illustrate a particular feature. DETAILED DESCRIPTION OF THE INVENTION

[0016]

[0023] In this document, the terms "radiation" and "beam" are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., having wavelengths of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm).

[0017]

[0024] The terms "reticle," "mask," or "patterning device," as used herein, may be broadly interpreted as referring to a general patterning device that can be used to impart a patterned cross-section to an incident radiation beam according to the pattern to be created in a target portion of a substrate. The term "light valve" may also be used in this context. In addition to traditional masks (transmissive or reflective; binary, phase-shifting, hybrid, etc.), other examples of such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0018]

[0025] Figure 1 shows a schematic diagram of a lithographic apparatus comprising: an illumination system (also called 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 coupled 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 coupled to a second positioner PW configured to accurately position the substrate support 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) of the substrate W. A controller 500 controls the overall operation of the apparatus. The controller 500 may be a centralized control system or a system of multiple separate sub-controllers within the various subsystems of the lithographic apparatus.

[0019]

[0026] In operation, the illumination system IL receives a radiation beam from the radiation source SO, for example via the 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 is 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.

[0020]

[0027] The term "projection system" PS as used herein should be interpreted broadly to encompass various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optics, or any combination thereof, as appropriate for the exposure radiation being used and / or other factors such as the use of an immersion liquid or a vacuum. Any use of the term "projection lens" herein may be considered as synonymous with the more general term "projection system" PS.

[0021]

[0028] The lithographic apparatus is of a type in which the substrate W can be at least partially covered by an immersion liquid having a relatively high refractive index (e.g. water) so as to fill an immersion space 11 between the projection system PS and the substrate W, which is also known as immersion lithography. More information about immersion techniques can be found in US Pat. No. 6,952,253, which is incorporated herein by reference.

[0022]

[0029] The lithographic apparatus may be of a type having two or more substrate supports WT (also known as "dual stage") In such a "multi-stage" machine, the substrate supports WT can be used in parallel, and / or a substrate W placed on one substrate support WT can be prepared for a next exposure while another substrate W on another substrate support WT is used to expose a pattern onto this other substrate W.

[0023]

[0030] In addition to the substrate support WT, the lithographic apparatus may comprise a measurement stage (not shown). 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 a system for supplying immersion liquid. The measurement stage may be moved below the projection system PS when the substrate support WT is spaced apart from the projection system PS.

[0024]

[0031] In operation, a radiation beam B is incident on a patterning device (e.g., mask) MA, which is held on a mask support MT, and is patterned by a pattern (design layout) present on the patterning device MA. After passing through 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. The substrate support WT can be accurately moved using the second positioner PW and the position measurement system IF to position various target portions C, for example, in the path of the radiation beam B at aligned and focused positions. Similarly, the patterning device MA can be accurately positioned with respect to the path of the radiation beam B using the first positioner PM and possibly further position sensors (not explicitly shown in FIG. 1 ). The patterning device MA and substrate W may 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, these marks may be located in spaces between the target portions. When the substrate alignment marks P1, P2 are located between target portions C, they are known as scribe-lane alignment marks.

[0025]

[0032] To clarify the present invention, a Cartesian coordinate system is used. This Cartesian coordinate system has three axes: x, y, and z. Each of these three axes is orthogonal to the other two. Rotation about the x axis is called Rx rotation, rotation about the y axis is called Ry rotation, and rotation about the z axis is called Rz rotation. The x and y axes define a horizontal plane, while the z axis is vertical. This 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, can 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.

[0026]

[0033] 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 an immersion space 11 between the apparatus's projection system PS (through which a patterned beam is projected onto the substrate W) and the substrate W. The immersion liquid covers at least a part of the substrate W below the final element of the projection system PS. Thus, at least the part of the substrate W that will be exposed is immersed in the immersion liquid.

[0027]

[0034] In commercial immersion lithography, the immersion liquid is water. The water here is typically highly pure distilled water, such as Ultra-Pure Water (UPW) commonly used in semiconductor fabrication plants. In immersion systems, the UPW is often purified and may undergo additional processing steps before being supplied to the immersion space 11 as the immersion liquid. In addition to water, other liquids with high refractive indices can also be used as immersion liquids, including, for example, hydrocarbons such as fluorocarbons, and / or aqueous solutions. Other fluids other than liquids are also contemplated for use in immersion lithography.

[0028]

[0035] In the description herein, reference is made to localized immersion where, in use, immersion liquid is confined in an immersion space 11 between the final element 100 and a surface facing the final element 100. This facing surface may be the surface of the substrate W or a surface of the support stage (or substrate support WT) that is flush with the surface of the substrate W. (Note that in the following, when reference is made to the surface of the substrate W, reference may additionally or alternatively be made to the surface of the substrate support WT, and vice versa, unless expressly stated otherwise.) A fluid handling structure 12 between the projection system PS and the substrate support WT is used to confine the immersion liquid to the immersion space 11. The immersion space 11, which is filled with immersion liquid, is smaller in plan than the top surface of the substrate W, and this immersion space 11 is kept substantially stationary relative to the projection system PS while the substrate W and substrate support WT move underneath.

[0029]

[0036] Other immersion systems are also envisaged, such as unconfined immersion systems (so-called "fully wetting" immersion systems) and bath-based immersion systems. In an unconfined immersion system, the immersion liquid covers more than the surface below the final element 100. The liquid outside the immersion space 11 exists as a thin liquid film. The liquid may cover the entire surface of the substrate W, or it may cover the substrate W and even the substrate support WT which is flush with the substrate W. In a bath-based system, the substrate W is fully immersed in a bath of immersion liquid.

[0030]

[0037] The fluid handling structure 12 is a structure that supplies and removes immersion liquid to and from the immersion space 11, thereby confining the immersion liquid in the immersion space 11. The structure includes features that form 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 includes piping to supply and remove immersion liquid from the immersion space 11, and is a structure that operates in response to relative movement of a stage below the projection system PS. In more recent designs, the immersion space 11 is partly defined by the fluid handling structure extending along at least part of the interface of the immersion space 11 between a final element 100 of the projection system PS and the substrate support WT or substrate W.

[0031]

[0038] The fluid handling structure 12 may have a selection of different functions, each of which may be derived from corresponding features that enable the fluid handling structure 12 to achieve that function. The fluid handling structure 12 may be referred to by a number of different names, each indicating a particular function, for example barrier member, seal member, fluid supply system, fluid removal system, liquid confinement structure, etc.

[0032]

[0039] Immersion liquid may be used as the immersion fluid, in which case the fluid handling structure 12 may be a liquid handling system. In the context of the above description, references in this paragraph to features defined in relation to a fluid may be understood to include features defined in relation to a liquid.

[0033]

[0040] The lithographic apparatus comprises a projection system PS. During exposure of a substrate W, the projection system PS projects a patterned radiation beam onto the substrate W. On reaching the substrate W, the path of the radiation beam B from the projection system PS passes through immersion liquid that is confined between the projection system PS and the substrate W by a fluid handling structure 12. The projection system PS comprises a lens element, which is the last part of the beam path that comes into contact with the immersion liquid. This lens element that comes into contact with the immersion liquid may also 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 the facing surface.

[0034]

[0041] Figure 2 shows schematically a localised liquid supply system or fluid handling system. The liquid supply system is provided with a fluid handling structure 12 (or liquid confinement structure) that extends along at least part of the boundary of the space 11 between the final element of the projection system PS and the support table WT or substrate W. The fluid handling structure 12 is substantially stationary in the XY plane relative to the projection system PS, although there may be some relative movement in the Z direction (in the direction of the optical axis). In one example, a seal is formed between the fluid handling structure 12 and the surface of the substrate W, and this may be a contactless seal such as a gas seal (such a system comprising a gas seal is disclosed in EP 1 420 298) or a liquid seal.

[0035]

[0042] The fluid handling structure 12 at least partly confines immersion liquid to a space 11 between the final element of the projection system PS and the substrate W. The space 11 is at least partly formed by the fluid handling structure 12 positioned below and surrounding the final element 100 of the projection system PS. Immersion liquid is brought into the space 11 below the projection system PS and within the fluid handling structure 12 by one of the liquid openings 13. Immersion liquid may be removed by another liquid opening 13. Immersion liquid may be brought into the space 11 via at least two liquid openings 13. Which liquid opening 13 is used to supply immersion liquid, and optionally which is used to remove immersion liquid, may depend on the direction of movement of the support table WT.

[0036]

[0043] In use, the immersion liquid may be contained in the space 11 by a contactless seal, such as a gas seal 16 formed by gas formed between the bottom of the fluid handling structure 12 and the surface of the substrate W. Gas in the gas seal 16 is supplied under pressure via an inlet 15 to the gap between the fluid handling structure 12 and the substrate W. The gas is extracted via an outlet 14. The overpressure at the gas inlet 15, the degree of vacuum at the outlet 14 and the shape of the gap are adjusted to create a high velocity inward gas flow that confines the immersion liquid. Such a system is disclosed in US 2004 / 0207824, which is incorporated herein by reference in its entirety. In one example, the fluid handling structure 12 does not include a gas seal 16.

[0037]

[0044] Figure 3 depicts a cross-sectional side view of another liquid supply or fluid handling system according to an embodiment. The arrangement shown in Figure 3 and described below can be applied to the lithographic apparatus described above and shown in Figure 1. The liquid supply system is provided with a fluid handling structure 12 (or liquid confinement structure) that extends along at least part of the boundary of the space 11 between the final element of the projection system PS and the support table WT or substrate W.

[0038]

[0045] The fluid handling structure 12 at least partly confines immersion liquid to a space 11 between the final element of the projection system PS and the substrate W. The space 11 is at least partly formed by the fluid handling structure 12 positioned below and surrounding the final element of the projection system PS. In one example, the fluid handling structure 12 comprises a body member 53 and a porous member 33. The porous member 33 is plate-shaped and has a plurality of holes (i.e. openings or pores). In one example, the porous member 33 is a mesh plate having a large number of small holes 84 formed in a network. Such a system is disclosed in US 2010 / 0045949 A1, which is incorporated herein by reference in its entirety.

[0039]

[0046] The body member 53 is provided with supply ports 72 capable of supplying immersion liquid to the space 11, and recovery ports 73 capable of recovering immersion liquid from the space 11. The supply ports 72 are connected to liquid supply devices 75 via passages 74. The liquid supply devices 75 are able to supply immersion liquid to the supply ports 72 through the corresponding passages 74. The recovery ports 73 are able to recover immersion liquid from the space 11. The recovery ports 73 are connected to liquid recovery devices 80 via passages 79. The liquid recovery device 80 recovers, via the passages 79, the immersion liquid recovered via the recovery ports 73. A porous member 33 is arranged in the recovery ports 73. By performing a liquid supply operation using the supply ports 72 and a liquid recovery operation using the porous member 33, a space 11 is formed between the projection system PS and the fluid handling structure 12 on one side, and between the projection system PS and the fluid handling structure 12 on the other side.

[0040]

[0047] Figure 4 represents, in plan view, a meniscus control feature of an alternative fluid handling structure 12 provided on the surface 20 (shown in Figure 2), which may have an outlet using the principle of gas drag, to which an embodiment of the present invention may relate. The illustrated feature of the meniscus control feature may, for example, replace the meniscus control feature described in Figure 2. The meniscus control feature of Figure 4 is in the form of an extractor, for example a two-phase extractor. The meniscus control feature comprises a plurality of discrete openings 50 in the surface 20 of the fluid handling structure 12. Although each discrete opening 50 is shown as circular, this is not necessarily so.

[0041]

[0048] Radially inward of the discrete openings 50, and in the surface 20 of the fluid handling structure 12, are a plurality of outlet openings 13 through which immersion liquid is supplied to the immersion space 11. The outlet openings 13 surround a space 11 that is bounded by apertures 17 formed in the fluid handling structure 12. Like the corresponding openings in Figure 2, the openings 13 can also be used to extract immersion liquid depending on the direction of substrate movement. A meniscus 320 is pinned between the discrete openings 50 by a resistance force induced by gas flow into the discrete openings 50.

[0042]

[0049] Radially outwardly of the meniscus control features (discrete openings 50) are a plurality of gas knife openings 60. In use, a flow of gas (e.g. a flow of humidified CO2) is supplied to the gas knife openings 60 to create a high pressure region at the surface of the substrate W which acts to move fluid that may be present at the surface of the substrate W away from the meniscus 320. In some embodiments, the gas knife openings 60 may be omitted.

[0043]

[0050] The geometry of the bottom of the fluid handling structure can vary. For example, any of the structures disclosed in US 2004 / 0207824 or US 2010 / 0313974 can be used in embodiments of the present invention. Embodiments of the present invention may be applied to fluid handling structures 12 having any planar shape or having features such as discrete openings 50 arranged in any shape, for example circular, square or diamond shaped. Also, where multiple gas knife openings 60 are provided, the gas knife openings 60 may be arranged in a similar shape to the discrete openings 50.

[0044]

[0051] In immersion lithography apparatuses, immersion liquid is often left behind on the surface of the substrate W after it has passed through. Immersion fluid left on the substrate W may form droplets and / or a film. Immersion liquid left on the substrate W is known to cause at least two problems. First, as the immersion liquid dries, it may leave drying spots (also known as watermarks) and / or affect the chemical properties of the resist. Second, when droplets strike the meniscus 320 of the immersion liquid confined in the immersion space 11, the meniscus 320 is disturbed, which can trap gas bubbles in the immersion liquid. Gas bubbles trapped in the immersion liquid may adhere to the surface of the substrate W or float freely in the immersion liquid. In either case, such gas bubbles can cause yield-reducing imaging defects. Strategies for mitigating bubbles are known, for example by ensuring that most or all of the environment near the meniscus is CO2, since CO2 dissolves in water faster than N2 or O2, so there is a higher chance that a CO2 bubble will dissolve before reaching the projection beam than there is an air bubble that will dissolve before reaching the projection beam.

[0045]

[0052] However, in order to provide a lithography apparatus with higher throughput, it is desirable to increase the relative movement speed between the substrate W and the immersion liquid. The higher the speed, the more likely it is that immersion liquid will be left behind on the substrate W, and the more likely it is that bubbles will be generated as a result of droplets on the surface of the substrate W colliding with the meniscus 320. Therefore, simply increasing the movement speed of the substrate W runs the risk of losing any increase in throughput due to a decrease in yield. Therefore, the present invention proposes an arrangement for preventing the generation of bubbles in the immersion liquid and / or watermarks on the photoresist due to liquid left behind on the substrate W.

[0046]

[0053] The present invention therefore proposes one or more immersion fluid recovery arrangements to be provided in the fluid handling structure 12 outside any immersion fluid confinement features of the fluid handling structure 12. The immersion fluid recovery arrangements are configured to remove immersion liquid from the surface of the substrate W, and in particular to remove immersion liquid that has escaped confinement in the immersion space 11 and remains on the surface of the substrate W. Various examples of immersion fluid recovery arrangements are shown in Figures 5A to 5D.

[0047]

[0054] 5A shows a simple example of an immersion fluid recovery arrangement 200 comprising an immersion fluid manipulator 201 and an immersion fluid recovery opening 202 from which immersion fluid can be extracted. The immersion fluid manipulator 201 comprises an elongated opening facing the top surface of the substrate W, connected to a high-pressure gas supply. Gas exhausting from the immersion fluid manipulator opening 201 creates a high-pressure region on the surface of the substrate W, which acts as a "wiper zone" to manipulate droplets or a film of immersion liquid that may be present on the surface of the substrate W. The immersion fluid manipulator opening 201 may be configured to form a gas knife on the substrate surface. The immersion fluid recovery opening 202 is connected to a lower pressure to extract the immersion liquid, for example as a two-phase flow. The immersion fluid recovery opening 202 may be connected to the same extraction channel as the discrete openings 50, or the outlet 14, or the recovery port 73. The immersion fluid recovery opening 202 may also be connected to a dedicated extraction channel.

[0048]

[0055] As the substrate W moves beneath the immersion fluid manipulator opening 201, the immersion liquid on the surface of the substrate W can be forced in a desired direction across the surface of the substrate W. In particular, the orientation of the immersion fluid manipulator opening 201 can be angled relative to the direction of movement of the substrate W. This means that droplets of immersion liquid on the surface of the substrate W are moved in a direction that has a component perpendicular to the direction of movement of the substrate W. Thus, the immersion liquid on the surface of the substrate W can be forced towards the immersion fluid recovery opening 202.

[0049]

[0056] 5A shows the immersion fluid manipulator opening 201 as an elongated slit, it will be appreciated that it may also be made up of a series of discrete openings arranged in a line. The discrete openings themselves may be slit-like, square, circular or any other suitable shape. Circular openings may be more suitable for manufacturing purposes. The gas supplied to the immersion fluid manipulator opening 201 may be, for example, CO2. The gas supplied to the immersion fluid manipulator opening 201 may be humidified to reduce the heat load caused by evaporation of the immersion liquid in the extraction channel. In particular, if the immersion fluid manipulator opening 201 is further from the meniscus 320, the gas supplied thereto may be air or artificial air (e.g., CDA or XCDA).

[0050]

[0057] The immersion fluid recovery openings 202 are located near the edges of the immersion fluid manipulator opening 201 so that, in use, there is a sufficient flow of gas from the immersion fluid manipulator opening 201 to the immersion fluid recovery openings 202 to draw immersion fluid remaining on the substrate W into the immersion fluid recovery openings 202. The immersion fluid recovery openings 202 are shown as circular in plan, which may be preferable for manufacturing purposes, although other shapes are possible. For example, elongated slits may be advantageous. The immersion fluid recovery openings 202 may be formed as a group of discrete openings of any suitable shape, in any suitable arrangement.

[0051]

[0058] 5B shows another immersion fluid recovery configuration 200a. The immersion fluid recovery configuration 200a differs from the immersion fluid recovery configuration 200 in that it includes a V-shaped immersion fluid manipulator opening 203. The immersion fluid recovery opening 202 is positioned within the V-shape of the immersion fluid manipulator opening 203, near its apex. The immersion fluid recovery configuration 200a is able to recover immersion fluid from a wider swath of the substrate W compared to the immersion fluid recovery configuration 200. The V-shaped arrangement of the immersion fluid manipulator opening 203, and the resulting wiper zone, ensures that the immersion fluid is guided through the immersion fluid recovery opening 202 to a location where it can be extracted, rather than simply being pushed around on the surface of the substrate W. The immersion fluid recovery configuration 200a may be the same as the immersion fluid recovery configuration 200, except for the shape of the immersion fluid manipulator opening 203.

[0052]

[0059] 5C shows another immersion fluid recovery arrangement 200b. The immersion fluid recovery arrangement 200b comprises an X-shaped immersion fluid manipulator opening 204 and a pair of immersion fluid recovery openings 202 arranged in opposite quadrants defined by the immersion fluid manipulator opening 204. The immersion fluid recovery arrangement 200b is effective for recovering immersion fluid from the surface of the substrate W as the substrate W moves either forward or backward along a line between the two immersion fluid recovery openings 202 (horizontally in the illustration). The immersion fluid recovery arrangement 200b may be the same as the immersion fluid recovery arrangement 200, except for the shape of the immersion fluid manipulator opening 204.

[0053]

[0060] 5D shows another immersion fluid recovery configuration 200c. The immersion fluid recovery configuration 200c comprises an X-shaped immersion fluid manipulator opening 205 and four immersion fluid recovery openings 202. One of the four immersion fluid recovery openings 202 is located in each quadrant defined by the X-shaped immersion fluid manipulator opening 205. It will be appreciated that the immersion fluid recovery configuration 200c is effective for recovering immersion liquid remaining on the surface of the substrate W, regardless of the direction in which the substrate is moving. Except for the number of immersion fluid recovery openings 202 and the shape of the immersion fluid manipulator opening 205, the immersion fluid recovery configuration 200c may be the same as the immersion fluid recovery configuration 200.

[0054]

[0061] It will be appreciated that the immersion fluid recovery arrangements 200, 200a, 200b, 200c may be located at any suitable location on the surface 20 of the fluid handling structure 12 facing the substrate W. Some possible locations are shown in Figure 6. The fluid handling structure shown in Figure 6 has fluid handling features, in particular gas knife openings 60 and meniscus control features (discrete openings 50), arranged in a quadrilateral shape. The quadrilateral resembles a rhombus or diamond (i.e. a square with diagonals parallel to the x and y axes), and this shape has been found to be effective for movement of the substrate W in the x and y directions relative to the fluid handling structure 12. Note that the sides of the quadrilateral are not straight but are slightly curved (concave), resulting in sharper corners of the quadrilateral.

[0055]

[0062] 6, an immersion fluid recovery arrangement 200a, each having a V-shaped immersion fluid manipulator opening 201, is disposed adjacent to each corner of a quadrilateral, and is oriented so that the vertices of the V-shape of the immersion fluid manipulator 203 point in the same direction as the corners of the quadrilateral. Another immersion fluid recovery arrangement 200e is disposed near the central region of each side of the quadrilateral, for example, near the midpoint of each side. Two or more immersion fluid recovery devices 200e may be provided adjacent to each side of the quadrilateral. The immersion fluid recovery arrangement 200e comprises a straight, elongated immersion fluid manipulator opening 201 and two immersion fluid recovery openings 202 adjacent to the ends of the immersion fluid manipulator opening 201 that are closest to the sides of the quadrilateral.

[0056]

[0063] The immersion fluid manipulator opening 201 of the immersion fluid recovery arrangement 200e extends at an angle relative to the side of the quadrilateral to which it adjoins. The immersion fluid manipulator opening 201 may extend perpendicular to the side of the quadrilateral, i.e., at a right angle to the tangent to the side at the closest point. More generally, the acute angle between the immersion fluid manipulator opening 201 and the side of the quadrilateral may be greater than 45°, greater than 60°, preferably greater than 70°, and even more preferably greater than 80°. The immersion fluid manipulator opening 201 may also be slightly curved, similar to a quadrilateral.

[0057]

[0064] The inventors have determined that the immersion fluid recovery arrangements 200e provided adjacent the midpoints of each side of the quadrilateral are effective in sweeping away immersion liquid remaining at the edge of the substrate W, particularly working in combination with the gas knife opening 60. This positioning is also effective for protecting parts of the meniscus 320 which may be vulnerable to the entrapment of air bubbles. The immersion fluid recovery arrangements 200a provided adjacent the corners of the quadrilateral are effective for collecting immersion liquid that has leaked out of the immersion space 11 due to film pulling. It will therefore be appreciated that the positions of the immersion liquid recovery arrangements 200, 200a, 200b, 200c may be selected based on either quickly collecting leaked immersion liquid or protecting locations where impact with droplets is most likely to cause the generation of air bubbles in the immersion space 11.

[0058]

[0065] 7 shows an embodiment in which two immersion fluid recovery arrangements 200a are provided on one side of the immersion space 11. In this embodiment, the substrate W moves in the direction shown by arrow V during exposure. These immersion fluid recovery arrangements 200a are positioned on the side where previous exposure took place in order to recover immersion fluid left over from the previous exposure. One immersion fluid recovery arrangement 200a is positioned close to the immersion space 11 to protect the meniscus 320 of the immersion liquid and prevent the generation of bubbles. The other immersion fluid recovery arrangement 200a is positioned away from the immersion space 11 and functions to recover immersion fluid from its previous path to prevent the formation of drying spots.

[0059]

[0066] The above-described immersion fluid recovery arrangements 200, 200a, 200b, 200c may be operated continuously while the substrate W is being scanned, or may be selectively operated at times or locations where immersion liquid is most likely to be present, or where the meniscus is more vulnerable to the formation of gas bubbles and / or watermarks. The immersion fluid manipulators 201, 203, 204, 205 and the immersion fluid recovery opening 202 may be operated together or separately as required. For example, at certain times in an exposure sequence, it may be desirable to operate only the immersion fluid manipulators 201, 203, 204, 205, to push residual immersion fluid into a gap at the edge of the substrate W where it can be recovered, rather than through the separate immersion fluid recovery opening 202.

[0060]

[0067] The present invention may provide a lithographic apparatus, which may have any / all of the other features or components of the lithographic apparatus as described above. For example, the lithographic apparatus may optionally include at least one or more of a radiation source SO, an illumination system IL, a projection system PS, a substrate support WT, etc.

[0061]

[0068] In particular, the lithographic apparatus may include a projection system PS configured to project a radiation beam B towards a region of the surface of the substrate W. Furthermore, the lithographic apparatus may include a fluid handling system as described in any of the above embodiments shown in Figures 2 to 4, and variants thereof.

[0062]

[0069] The lithographic apparatus may include an actuator (not shown) configured to move the substrate W relative to the fluid handling system. The actuator may thus be used to control the position of the substrate W (or alternatively the position of the fluid handling system). The actuator may be or may include a substrate support (e.g., substrate table) WT, and / or a substrate holder constructed to hold the substrate W, and / or a second positioner PW configured to accurately position the substrate support WT.

[0063]

[0070] Although specific reference is made in this specification to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as 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.

[0064]

[0071] Where circumstances permit, 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 that 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, a machine-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic storage media, optical storage media, flash memory devices, or electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.). Also, firmware, software, routines, or instructions may be described herein as performing certain actions. However, it should be understood that such description is for convenience only, and that such actions are actually due to a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., which may cause actuators or other devices to interact with the physical world.

[0065]

[0072] Although specific reference is made herein to embodiments of the invention in the context of 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 are sometimes referred to generically as lithography tools. Such lithography tools may use ambient (non-vacuum) conditions.

[0066]

[0073] Although specific reference is made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that, where circumstances permit, the invention is not limited to optical lithography.

[0067]

[0074] Embodiments include the following numbered clauses: 1. A fluid handling structure for an immersion lithography apparatus, the fluid handling structure being configured to confine immersion liquid in a space between a bottom surface of the fluid handling structure and a substrate and / or a surface of a substrate support supporting the substrate, the fluid handling structure having a feature in the bottom surface having a substantially polygonal shape defined by a plurality of sides, an opening configured to supply immersion fluid to said space, an extractor configured to extract immersion fluid from said space, and an immersion fluid recovery arrangement outside the feature and adjacent to a side of the feature, the immersion fluid recovery arrangement including an immersion fluid manipulator configured to form an elongated wiper zone extending at an angle to said side of the feature, and an immersion fluid recovery opening for extracting immersion fluid. 2. The fluid handling system of clause 1, wherein the immersion fluid manipulator includes a gas knife. 3. A fluid handling structure according to clause 2, wherein the gas knife forms a high pressure region as an elongated wiper zone on the surface of the substrate and / or substrate support. 4. A fluid handling structure according to clause 1, 2 or 3, wherein the acute angle between the elongate wiper zone and a side of the feature is greater than 45°, greater than 60°, preferably greater than 75°, more preferably greater than 85°. 5. The fluid handling structure of any preceding clause, wherein the immersion fluid manipulator is configured to form an additional elongated wiper zone extending at an angle to the elongated wiper zone. 6. A fluid handling structure according to clause 5, wherein the additional elongate wiper zone extends at an angle to the elongate wiper in the range of 60° to 90°, preferably in the range of 75° to 90°, more preferably in the range of 85° to 90°. 7. A fluid handling structure according to any preceding clause wherein the immersion fluid manipulator is adjacent to a central region of said one side, desirably adjacent to a central region comprising the central third of said one side. 8. The fluid handling structure according to any preceding clause, wherein the immersion fluid recovery arrangement comprises a plurality of immersion fluid recovery openings. 9. A fluid handling structure according to clause 8, wherein the immersion fluid recovery arrangement comprises an immersion fluid recovery opening on each side of the immersion fluid manipulator. 10. A fluid handling structure according to any preceding clause, having a plurality of immersion fluid recovery arrangements. 11. A fluid handling structure according to clause 10, wherein the number of immersion fluid recovery arrangements is the same as or greater than the number of sides of the feature. 12. A fluid handling structure according to any preceding clause, wherein the feature includes a gas knife and / or said extractor. 13. A lithographic apparatus comprising: a substrate holder configured to hold a substrate; a projection system configured to project a beam of radiation onto the substrate held in the substrate holder; and a fluid handling structure according to any preceding clause. 14. A device manufacturing method in a lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held in the substrate holder, and a fluid handling structure according to any preceding clause, the method comprising using the fluid handling structure to confine immersion fluid to a space between a surface of the substrate and at least part of the fluid handling structure, and using an immersion fluid recovery arrangement to recover immersion fluid that escapes confinement by the fluid handling structure. 15. A method according to clause 14, wherein the immersion fluid recovery arrangement is activated when the relative velocity between the fluid handling structure and the substrate is greater than a predetermined threshold velocity. 16. A method according to clause 14, wherein the fluid handling structure has a plurality of immersion fluid recovery arrangements, the immersion fluid recovery arrangements being selectively actuated depending on the direction of relative movement between the fluid handling structure and the substrate.

[0068]

[0075] While specific embodiments of the present invention have been described above, it will be apparent that the invention may be practiced otherwise than as described. The foregoing description is intended to be illustrative rather than limiting. Accordingly, 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 appended claims.

Claims

1. 1. A fluid handling structure for an immersion lithographic apparatus configured to confine immersion liquid to a space between a bottom surface of the fluid handling structure and a surface of a substrate and / or a substrate support supporting the substrate, the structure comprising: a feature in the base surface having a substantially polygonal shape defined by a plurality of sides; an opening configured to supply immersion fluid to the space; an extractor configured to extract immersion fluid from the space; an immersion fluid recovery arrangement outside the feature and proximate to a side of the feature, the immersion fluid recovery arrangement including an immersion fluid manipulator configured to form an elongated wiper zone extending at an angle to the side of the feature, and an immersion fluid recovery opening for extracting immersion fluid; 1. A fluid handling structure comprising:

2. The fluid handling system of claim 1 , wherein the immersion fluid manipulator comprises a gas knife.

3. The fluid handling structure of claim 2 , wherein a gas knife forms a high pressure region as the elongated wiper zone on the surface of the substrate and / or substrate support.

4. 4. The fluid handling structure of claim 1 , wherein the acute angle between the elongated wiper zone and the side of the feature is greater than 45°, greater than 60°, preferably greater than 75°, more preferably greater than 85°.

5. The fluid handling structure of any preceding claim, wherein the immersion fluid manipulator is configured to define an additional elongated wiper zone extending at an angle to the elongated wiper zone.

6. 6. The fluid handling structure of claim 5, wherein the additional elongate wiper zone extends at an angle to the elongate wiper in the range of 60° to 90°, desirably in the range of 75° to 90°, more desirably in the range of 85° to 90°.

7. The fluid handling structure of any preceding claim, wherein the immersion fluid manipulator is adjacent to a central region of said one side, desirably said central region comprising the central third of said one side.

8. The fluid handling structure according to any preceding claim, wherein the immersion fluid recovery arrangement comprises a plurality of immersion fluid recovery openings.

9. The fluid handling structure of claim 8 , wherein the immersion fluid recovery arrangement comprises an immersion fluid recovery opening on each side of the immersion fluid manipulator.

10. The fluid handling structure according to any preceding claim, comprising a plurality of immersion fluid recovery arrangements.

11. The fluid handling structure of claim 10 , wherein the number of immersion fluid recovery arrangements is the same as or greater than the number of sides of the feature.

12. The fluid handling structure of any preceding claim, wherein the feature comprises a gas knife and / or the extractor.

13. 13. A lithographic apparatus comprising: a substrate holder configured to hold a substrate; a projection system configured to project a beam of radiation onto the substrate held by the substrate holder; and a fluid handling structure according to any preceding claim.

14. 14. A device manufacturing method in a lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a beam of radiation onto the substrate held in the substrate holder, and a fluid handling structure according to any preceding claim, the method comprising: using the fluid handling structure to confine immersion fluid to a space between a surface of the substrate and at least part of the fluid handling structure; using the immersion fluid recovery arrangement to recover immersion fluid that escapes confinement by the fluid handling structure; and A device manufacturing method comprising:

15. 15. A device manufacturing method according to claim 14, wherein the immersion fluid recovery arrangement is activated when the relative velocity between the fluid handling structure and the substrate is greater than a predetermined threshold velocity, or wherein the fluid handling structure has a plurality of immersion fluid recovery arrangements, the immersion fluid recovery arrangements being selectively activated depending on the direction of relative movement between the fluid handling structure and the substrate.

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