Fluid treatment system and method

Abstract

A fluid treatment system includes a liquid confinement structure (12), a gas supply conduit (70), and a fluid delivery conduit (80). The liquid confinement structure is configured to confine an immersion fluid within a space between at least a portion of the liquid confinement structure and a surface of the substrate. The gas supply conduit is configured to supply fluid to the space. The gas supply conduit has a flow controller (71) configured to control the supply of gas from the gas supply conduit. The fluid delivery conduit is configured to deliver fluid drawn from the space. The fluid delivery conduit has a flow meter (81) configured to measure a flow rate of gas in the fluid delivery conduit. In a calibration mode, gas supplied by the flow controller flows directly to the fluid delivery conduit via a bypass conduit (90), where the bypass conduit bypasses the liquid confinement structure.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to EP application 22216821.3, filed on December 27, 2022, the entire content of which is incorporated herein by reference. Technical field

[0003] The present invention relates to a fluid handling system and a method for calibrating a flow meter in a fluid handling system. Background art

[0004] A lithographic apparatus is a machine for applying a desired pattern onto a substrate. For example, a lithographic apparatus can be used to manufacture integrated circuits (ICs). For example, a lithographic apparatus can project a pattern of a patterning device (e.g., a mask), often also referred to as a "design layout" or "design", onto a layer of radiation - sensitive material (resist) provided on a substrate (e.g., a wafer). Known lithographic apparatuses include so - called steppers, in which each target portion is irradiated by exposing the entire pattern at once onto the target portion; and so - called scanners, in which each target portion is irradiated by scanning the pattern with a radiation beam in a given direction ("scan" direction), while synchronously scanning the substrate in a direction parallel or anti - parallel to this direction.

[0005] As semiconductor manufacturing processes have advanced, the dimensions of circuit elements have been continuously reduced, while the number of functional elements (e.g., transistors) per device has steadily increased over several decades, following a trend commonly known as "Moore's Law". To follow "Moore's Law", the semiconductor industry is pursuing technologies that can fabricate ever - smaller features. To project a pattern onto a substrate, a lithographic apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features patterned on the substrate. Typically used wavelengths currently are 365 nm (i - line), 248 nm, 193 nm, and 13.5 nm.

[0006] By providing an immersion fluid (e.g., water) having a relatively high refractive index on the substrate during the exposure process, the resolution of smaller features can be further improved. Since the exposure radiation will have a shorter wavelength in the immersion fluid than in air, the role of the immersion fluid is to be able to image smaller features. The role of the immersion fluid can also be understood as increasing the effective numerical aperture (NA) of the system and also increasing the depth of focus.

[0007] The immersion fluid can be confined by a fluid handling system to a local area (referred to as the immersion space) between a liquid confinement structure of a lithographic apparatus and a substrate. A fluid (e.g., carbon dioxide gas) is supplied to the immersion space through a flow controller. The supplied fluid is then withdrawn again from the immersion space through a fluid delivery piping system. In the fluid delivery piping system, the flow rate is measured by a flow meter.

[0008] The performance of the fluid handling system may be sensitive to the flow rate setting of the fluid supplied through the immersion space. The accuracy of the flow controller and the flow meter may be degraded over time. SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide a fluid handling system and method in which measures are taken to increase throughput and / or reduce defects on a substrate.

[0010] According to a first aspect of the present invention, there is provided a fluid handling system comprising a liquid confinement structure, a gas supply pipe, and a fluid delivery pipe. The liquid confinement structure is configured to confine an immersion fluid within a space between at least a portion of the liquid confinement structure and a surface of a substrate. The gas supply pipe is in fluid communication with the liquid confinement structure and is configured to supply a fluid to the space. The gas supply pipe has a flow controller configured to control the supply of gas from the gas supply pipe. The fluid delivery pipe is in fluid communication with the liquid confinement structure and is configured to convey the fluid withdrawn from the space. The fluid delivery pipe has a flow meter configured to measure the flow rate of the gas in the fluid delivery pipe. In a calibration mode, the gas supply pipe is in direct fluid communication with the fluid delivery pipe via a bypass pipe, wherein the bypass pipe bypasses the liquid confinement structure, and the gas supplied by the flow controller flows directly into the fluid delivery pipe via the bypass pipe.

[0011] According to a second aspect of the present invention, there is provided a method for calibrating a flow meter in a fluid handling system. The fluid handling system includes: a liquid confinement structure configured to confine an immersion fluid within a space between at least a portion of the liquid confinement structure and a surface of a substrate; a gas supply conduit in fluid communication with the liquid confinement structure and configured to supply fluid to the space, the gas supply conduit having a flow controller configured to control the supply of gas from the gas supply conduit; and a fluid delivery conduit in fluid communication with the liquid confinement structure and configured to extract fluid from the space, the fluid delivery conduit having a flow meter configured to measure the flow rate of gas in the fluid delivery conduit. The method includes: setting the system to a calibration mode in which: the gas supply conduit is in direct fluid communication with the fluid delivery conduit via a bypass conduit, and the measured flow rate of gas in the fluid delivery conduit is compared with the flow rate of gas provided by the flow controller. The bypass conduit bypasses the liquid confinement structure, and the gas provided by the flow controller flows directly through the bypass conduit into the fluid delivery conduit.

[0012] In the following, further embodiments, features, and advantages of the present invention, as well as the structure and operation of each embodiment, feature, and advantage, will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which corresponding reference numerals represent corresponding components, wherein:

[0014] Figure 1 A schematic diagram of a lithographic apparatus is depicted;

[0015] Figure 2a 、 Figure 2b 、 Figure 2c and Figure 2d Two different versions of a fluid handling system are depicted in cross-sectional form, the fluid handling system having different features depicted on the left and right sides of each version, which may extend around the entire circumference;

[0016] Figure 3 A fluid handling system is depicted that includes a gas supply conduit, a fluid delivery conduit, and a bypass conduit, the gas supply conduit, fluid delivery conduit, and bypass conduit being configured such that in a calibration mode, the gas supply conduit is in direct fluid communication with the fluid delivery conduit via the bypass conduit;

[0017] Figure 4Depicts a fluid handling system that includes a gas supply conduit, a plurality of fluid delivery conduits, and corresponding bypass conduits, where each bypass conduit is configured such that in a calibration mode, the gas supply conduit is in direct fluid communication with one of the plurality of fluid delivery conduits via the corresponding bypass conduit;

[0018] Figure 5 Depicts a fluid handling system that includes a gas supply conduit, a plurality of fluid delivery conduits, and bypass conduits, where the bypass conduits are configured such that in a calibration mode, the gas supply conduit is in direct fluid communication with one of the plurality of fluid delivery conduits via the bypass conduits.

[0019] The features shown in the figures are not necessarily drawn to scale, and the dimensions and / or arrangements are not restrictive. It will be understood that the figures include optional features that may not be essential to the invention. In addition, not every figure depicts all features of the device, and the figures may only show some components relevant to the description of a particular feature. Detailed Description

[0020] 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).

[0021] The terms "reticle", "mask", or "patterning device" as used herein can be broadly understood to refer to a general patterning device that can be used to impart a patterned cross-section to an incident radiation beam that corresponds to a pattern to be formed in a target portion of a substrate. The term "light valve" can also be used in this context. Examples of other such patterning devices include programmable mirror arrays and programmable liquid crystal display arrays in addition to classical masks (transmission or reflection, binary, phase-shifting, hybrid, etc.).

[0022] Figure 1Schematically depicts a lithographic apparatus. The lithographic apparatus includes: an illumination system (also referred to as an illuminator) IL for conditioning a radiation beam B (e.g., UV radiation or DUV radiation); a mask support (e.g., a mask table) MT for supporting a patterning device (e.g., a mask) MA and connected to a first positioning device PM for accurately positioning the patterning device MA in accordance with certain parameters; a substrate support (e.g., a substrate table) WT for holding a substrate (e.g., a wafer coated with resist) W and connected to a second positioning device PW for accurately positioning the substrate support WT in accordance with certain parameters; and a projection system (e.g., a refractive projection lens system) PS for projecting a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., including one or more dies) of the substrate W. A controller 500 controls the overall operation of the device. The controller 500 can be a centralized control system or a system of multiple individual sub-controllers within the various subsystems of the lithographic apparatus.

[0023] In operation, the illumination system IL receives the radiation beam B from a radiation source SO, e.g., via a beam delivery system BD. The illumination system IL can include various types of optical components for guiding, shaping, and / or controlling the radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof. The illuminator IL can be used to condition the radiation beam B to have a desired spatial and angular intensity distribution in a cross-section at the plane of the patterning device MA.

[0024] The term "projection system" PS as used herein should be broadly construed to encompass various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, depending on the exposure radiation used, and / or other factors such as the use of an immersion liquid or the use of a vacuum. The term "projection lens" as used herein can be considered synonymous with the more general term "projection system" PS.

[0025] The lithographic apparatus is of a type in which at least a portion of the substrate W can be covered by an immersion liquid having a relatively high refractive index (e.g., water), thereby filling the immersion space 11 between the projection system PS and the substrate W - this is also known as immersion lithography. For more information on immersion techniques, see U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0026] A lithographic apparatus can be of a type having two or more substrate supports WT (also referred to as “dual stage”). In such a “multi-stage” apparatus, the substrate supports WT can be used in parallel, and / or preparatory steps for exposing a subsequent substrate W can be performed on a substrate W located on one of the substrate supports WT, while a pattern on another substrate W located on another substrate support WT is being exposed.

[0027] In addition to the substrate support WT, the lithographic apparatus may also include a metrology stage (not shown). The metrology stage is arranged to hold sensors and / or cleaning devices. The sensors can be arranged to measure properties of the projection system PS or the radiation beam B. The metrology stage can hold a plurality of sensors. The cleaning devices can be arranged to clean a part of the lithographic apparatus, such as a part of the projection system PS or a part of the system providing the immersion liquid. When the substrate support WT is moved away from the projection system PS, the metrology stage can move under the projection system PS.

[0028] In operation, the radiation beam B is incident on a patterning device (e.g., a mask MA), which is held on a mask support MT and patterned by a pattern (design layout) present on the patterning device MA. After passing through the mask MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. By means of a second positioner PW and a position measurement system IF, the substrate support WT can be moved precisely, e.g., to position different target portions C in the path of the radiation beam B at a focused and aligned position. Similarly, a first positioner PM and possibly another position sensor ( Figure 1 another position sensor is not explicitly shown in) can be used to precisely position the patterning device MA relative to the path of the radiation beam B. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 can be used to align the patterning device MA and the substrate W. Although the substrate alignment marks P1, P2 as shown in the figure occupy dedicated target portions, the substrate alignment marks P1, P2 can also be located in the gaps between the target portions. When the substrate alignment marks P1, P2 are located between the target portions C, the substrate alignment marks P1, P2 are referred to as scribe alignment marks.

[0029] To illustrate the present invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes, namely the x-axis, the y-axis, and the z-axis. Each of these three axes is orthogonal to the other two axes. A rotation about the x-axis is referred to as an Rx rotation. A rotation about the y-axis is referred to as an Ry rotation. A rotation about the z-axis is referred to as an Rz rotation. The x-axis and the y-axis define a horizontal plane, while the z-axis is in the vertical direction. The Cartesian coordinate system does not limit the present invention and is only used for illustration. Another coordinate system, such as a cylindrical coordinate system, can also be used to illustrate the present invention. The orientation of the Cartesian coordinate system can be different, for example, such that the z-axis has a component along the horizontal plane.

[0030] Immersion technology has been introduced into lithography systems to improve the resolution of smaller features. In an immersion lithography apparatus, a liquid layer of an immersion liquid having a relatively high refractive index is disposed in an immersion space 11 between the projection system PS of the apparatus and the substrate W (through which the patterned beam is projected onto the substrate W). The immersion liquid covers at least the portion of the substrate W under the final element of the projection system PS. Thus, at least the portion of the substrate W that is undergoing exposure is immersed in the immersion liquid.

[0031] In commercial immersion lithography technology, the immersion liquid is water. Generally, the water is highly purified distilled water, such as ultrapure water (UPW) commonly used in semiconductor manufacturing plants. In an immersion system, the UPW is typically purified and may also undergo additional processing steps before being delivered as the immersion liquid to the immersion space 11. In addition to water, other liquids having a relatively high refractive index can also be used as the immersion liquid, such as: hydrocarbons, such as fluorocarbons; and / or aqueous solutions. Furthermore, in addition to liquids, other fluids have also been envisioned for use in immersion lithography technology.

[0032] In the present specification, a local immersion technology will be referred to, in which the immersion liquid is restricted to the immersion space 11 located between the final element 100 and the surface facing the final element 100. The facing surface is the surface of the substrate W or the surface of a support stage (or substrate support WT) coplanar with the surface of the substrate W. (Note that, additionally or alternatively, unless otherwise explicitly stated, the surface of the substrate W mentioned hereinafter also refers to the surface of the substrate support WT; and vice versa). A fluid handling structure 12 located between the projection system PS and the substrate support WT is used to restrict the immersion liquid within the immersion space 11. The immersion space 11 filled with the immersion liquid is smaller than the top surface of the substrate W in a plane, and the immersion space 11 remains substantially stationary relative to the projection system PS, while the substrate W and the substrate support WT move thereunder.

[0033] Other immersion systems have been envisioned, such as an unbounded immersion system (i.e., the so-called "fully wet" immersion system) and a bath immersion system. In an unbounded immersion system, the immersion liquid covers more than just the surface below the final element 100. The liquid outside the immersion space 11 exists in the form of a thin liquid film. The liquid can cover the entire surface of the substrate W, and even cover the substrate W and the substrate support WT coplanar with the substrate W. In a bath-type system, the substrate W is completely immersed in a bath of immersion liquid.

[0034] The fluid handling structure 12 is a structure that supplies immersion liquid to the immersion space 11 and removes immersion liquid from the immersion space 11, thereby confining the immersion liquid within the immersion space 11. The fluid handling structure 12 includes features that are part of a fluid supply system. The arrangement disclosed in PCT patent application publication number WO99 / 49504 is an early fluid handling structure that includes a pipe for supplying immersion liquid to or recovering immersion liquid from the immersion space 11, and the pipe operates depending on the relative movement of the stage below the projection system PS. In a newer design, the fluid handling structure extends along at least a portion of the boundary of the immersion space 11 between the final element 100 of the projection system PS and the substrate support WT or the substrate W, thereby partially defining the immersion space 11.

[0035] The fluid handling structure 12 can have options with different functions. Each function can be derived from the corresponding features that enable the fluid handling structure 12 to achieve that function. The fluid handling structure 12 can be referred to by a variety of different terms, each term referring to a function, such as a barrier member, a sealing member, a fluid supply system, a fluid removal system, a liquid confinement structure, etc.

[0036] As a barrier member, the fluid handling structure 12 is a barrier for blocking the outflow of immersion liquid from the immersion space 11. As a liquid confinement structure, this structure confines the immersion liquid within the immersion space 11. As a sealing member, the sealing features of the fluid handling structure 12 form a seal to confine the immersion liquid within the immersion space 11. The sealing features can include additional gas flow from openings in the surface of the sealing member, such as an air knife.

[0037] In an embodiment, the fluid handling structure 12 can supply immersion fluid and thus become a fluid supply system.

[0038] In an embodiment, the fluid handling structure 12 can at least partially confine the immersion fluid and thus become a fluid confinement system.

[0039] In an embodiment, the fluid handling structure 12 can provide a barrier for the immersion fluid and thus become a barrier member, such as a fluid confinement structure.

[0040] In an embodiment, the fluid handling structure 12 may generate or use a gas flow, for example to help control the flow and / or position of the immersion fluid.

[0041] The flow of gas may form a seal to confine the immersion fluid and thus the fluid handling structure 12 may be referred to as a sealing member; such a sealing member may be a fluid confinement structure.

[0042] In an embodiment, an immersion liquid is used as the immersion fluid. In this case, the fluid handling structure 12 may be a liquid handling system. With reference to the preceding description, references in this paragraph to features defined with respect to a fluid may be understood to include features defined with respect to a liquid.

[0043] The lithographic apparatus has a projection system PS. During exposure of the substrate W, the projection system PS projects a patterned radiation beam onto the substrate W. In order to reach the substrate W, the path of the radiation beam B from the projection system PS passes through an 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, which is located at the last position of the path of the beam and is in contact with the immersion liquid. This lens element in contact with the immersion liquid may be referred to as a "last lens element" or a "final element". The final element 100 is at least partially surrounded by the fluid handling structure 12. The fluid handling structure 12 may confine the immersion liquid below the final element 100 and above the facing surface.

[0044] Figure 2a , Figure 2b , Figure 2c and Figure 2d Different features that may exist in variations of fluid handling systems are shown. Unless otherwise noted, these designs may share similar Figure 2a , Figure 2b , Figure 2c and Figure 2d The features described herein may be selected individually or in combination as shown or desired. The figures depict different versions of a fluid treatment system having different features shown on the left and right, which may extend around the entire circumference. Thus, for example, a fluid treatment system may have the same features extending around the entire circumference. For example, a fluid treatment system may have only Figure 2a The feature on the left side of Figure 2a The feature on the right side of Figure 2b The feature on the left side of Figure 2b The feature on the right side of Figure 2c The feature on the left side of Figure 2c The feature on the right side of Figure 2d The feature on the left side of Figure 2dFeatures on the right side. Alternatively, the fluid handling system can be provided with any combination of features from these figures at different positions around the circumference. The fluid handling system can include the fluid handling structure 12 described in the variant examples below.

[0045] Figure 2a The fluid handling structure 12 around the bottom surface of the final element 100 is shown. The final element 100 has an inverted frustoconical shape. The frustoconical shape has a flat bottom surface and a conical surface. The frustoconical shape projects from the flat surface and has a bottom flat surface. The bottom flat surface is the optically effective part of the bottom surface of the final element 100 through which the radiation beam B can pass. The final element 100 can have a coating 30. The fluid handling structure 12 at least surrounds a part of the frustoconical shape. The fluid handling structure 12 has an inner surface facing the conical surface of the frustoconical shape. The inner surface and the conical surface can have complementary shapes. The top surface of the fluid handling structure 12 can be substantially flat. The fluid handling structure 12 can be mounted around the frustoconical shape of the final element 100. The bottom surface of the fluid handling structure 12 can be substantially flat and, in use, this bottom surface can be parallel to the facing surface of the substrate support WT and / or the substrate W. Thus, the bottom surface of the fluid handling structure 12 can be referred to as the surface facing the surface of the substrate W. The distance between the bottom surface and the facing surface can be in the range of 20 micrometers to 500 micrometers, desirably in the range of 70 micrometers to 200 micrometers.

[0046] The fluid handling structure 12 extends closer to the facing surface of the substrate W and the substrate support WT than the final element 100. Thus, the immersion space 11 is defined between the inner surface of the fluid handling structure 12, the plane of the frustoconical portion, and the facing surface. During use, the immersion space 11 is filled with immersion liquid. The immersion liquid fills at least a part of the buffer space between the complementary surfaces located between the final element 100 and the fluid handling structure 12, and in an embodiment, fills at least a part of the space between the complementary inner surface and the conical surface.

[0047] The immersion liquid is supplied to the immersion space 11 through an opening formed in the surface of the fluid handling structure 12. The immersion liquid can be supplied through the supply opening 20 located in the inner surface of the fluid handling structure 12. Alternatively or additionally, the immersion liquid is supplied from the lower supply opening 23 formed in the bottom surface of the fluid handling structure 12. The lower supply opening 23 can surround the path of the radiation beam B, and the lower supply opening 23 can be formed by an array of a series of openings or a single slit. The immersion liquid is supplied to fill the immersion space 11 such that the flow passing through the immersion space 11 under the projection system PS is laminar. Supplying the immersion liquid from the lower supply opening 23 additionally prevents air bubbles from entering the immersion space 11. This supply of the immersion liquid can act as a liquid seal.

[0048] The immersion liquid can be recovered from the recovery opening 21 formed in the inner surface. The immersion liquid can be recovered through the recovery opening 21 by applying a negative pressure; the recovery through the recovery opening 21 is the result of the flow rate of the immersion liquid flowing through the immersion space 11; alternatively, the recovery can be the result of both of them. In a plan view, the recovery opening 21 can be located on the opposite side of the supply opening 20. Additionally or alternatively, the immersion liquid can be recovered through the overflow recovery port 24 located on the top surface of the fluid processing structure 12. The functions of the supply opening 20 and the recovery opening 21 can be interchanged (i.e., the flow direction of the liquid is reversed). This allows the direction of the flow to be changed according to the relative movement of the fluid processing structure 12 and the substrate W.

[0049] Additionally or alternatively, the immersion liquid can be recovered from below the fluid processing structure 12 through the recovery opening 25 formed in the bottom surface of the fluid processing structure 12. The recovery opening 25 can be used to hold the meniscus 33 of the immersion liquid onto the fluid processing structure 12. The meniscus 33 is formed between the fluid processing structure 12 and the facing surface, and the meniscus 33 serves as a boundary between the liquid space and the external gaseous environment. The recovery opening 25 can be a porous plate, and the porous plate can recover the immersion liquid in the form of a substantially single-phase flow. The recovery opening in the bottom surface can be a series of pinning openings 32, and the immersion liquid is recovered through these pinning openings 32. The pinning openings 32 can recover the immersion liquid in the form of a two-phase flow.

[0050] Optionally, an air knife opening 26 is provided radially outside relative to the inner surface of the fluid processing structure 12. Gas can be supplied through the air knife opening 26 at a higher speed to assist in liquid confinement of the immersion liquid in the immersion space 11. The supplied gas can be moist, and the supplied gas can mainly contain carbon dioxide. Radially outside the air knife opening 26 is a gas recovery opening 28 for recovering the gas supplied through the air knife opening 26.

[0051] Additional openings, such as openings leading to the atmosphere, a gas source, or a vacuum, can be present in the bottom surface of the fluid processing structure 12 (i.e., the surface of the fluid processing structure 12 facing the substrate W). In Figure 2a An example of such optional additional openings 50 is shown by the dashed line on the right side. As shown, the additional opening 50 can be a supply or extraction member represented by a two-way arrow. For example, if configured as a supply device, the additional opening 50 can be connected to a liquid supply device or a gas supply device like any supply member. Alternatively, if configured as an extraction device, the additional opening 50 can be used to extract fluid and can be connected to, for example, the atmosphere, a gas source, or a vacuum. For example, at least one additional opening 50 can be located between the air knife opening 26 and the gas recovery opening 28, and / or between the pinning openings 32 and the air knife opening 26.

[0052] Figure 2a Two different versions of the fluid handling structure 12 on the left and right sides fix or pin the meniscus 33. Due to the fixed position of the pinning opening 32, in Figure 2a the version of the fluid handling structure 12 on the right side can pin the meniscus 33 at a position that is substantially fixed relative to the final element 100. In Figure 2a the version of the fluid handling structure 12 on the left side can pin the meniscus 33 below the recovery opening 25, and thus the meniscus 33 can move along the length and / or width of the recovery opening 25. In order for the radiation beam B to be directed to the entire side of the substrate W being exposed, the substrate support WT supporting the substrate W is moved relative to the projection system PS. In order to maximize the output of the substrate W exposed by the lithographic apparatus, the substrate support WT (and the substrate W) is moved as fast as possible. However, there is a critical relative speed (commonly referred to as the critical scan speed) - above which the meniscus 33 located between the fluid handling structure 12 and the substrate W becomes unstable. An unstable meniscus 33 has a greater risk of losing the immersion liquid in the form of, for example, one or more drops. In addition, especially when the confined immersion liquid crosses the edge of the substrate W, an unstable meniscus 33 has a greater risk of causing bubbles to be included in the immersion liquid.

[0053] The droplets present on the surface of the substrate W may impose a heat load and may be a source of defects. The droplets may evaporate, leaving dry stains, the droplets may move, thereby transporting contaminants (such as particles), the droplets may collide with the larger body of the immersion liquid, thereby introducing bubbles into the larger body, and the droplets may evaporate, imposing a heat load on the surface where the droplets are located. If this surface is related to the positioning of the components of the lithographic apparatus relative to the substrate W being imaged, such heat loads may be a cause of deformation and / or a source of positioning errors. Therefore, it is not desirable to form droplets on the surface. Therefore, in order to avoid forming such droplets, the speed of the substrate support WT is limited to the critical scan speed at which the meniscus 33 remains stable. This limits the throughput of the lithographic apparatus.

[0054] Figure 2a The left side of the fluid handling system in 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. Thus, the spring 60 can be used to control the height of the fluid handling structure 12 above the substrate W. Such adjustable passive springs are described in US 7,199,874, the entire content of which is incorporated herein by reference. Other biasing devices may also be applicable, such as biasing devices using electromagnetic forces. Although the spring 60 is shown in Figure 2ato the left of, but the spring 60 is optional and need not be included together with other features to the left of Figure 2a Although the spring 60 is not shown in any of the other figures, it may also be included in other variants of the fluid handling system described in connection with Figure 2a , 2b , 2c or 2d.

[0055] Figure 2b Two different versions of the fluid handling structure 12 are shown to its left and to its right. The two different versions of the fluid handling structure 12 allow the meniscus 33 to move relative to the final element 100. The meniscus 33 can move in the direction of the moving substrate W. This reduces the relative speed between the meniscus 33 and the moving substrate W, which can result in increased stability of the meniscus 33 and a reduced risk of rupture of the meniscus 33. The speed of the substrate W at which the meniscus 33 ruptures increases, thereby allowing the substrate W to move faster under the projection system PS. Thus, the production volume is increased.

[0056] Figure 2b The same features as shown in Figure 2a are given the same reference numerals. The fluid handling structure 12 has an inner surface complementary to the conical surface of a frustoconical shape. The bottom surface of the fluid handling structure 12 is closer to the facing surface than the flat bottom surface of the frustoconical shape.

[0057] The immersion liquid is supplied to the immersion space 11 through a supply opening 34 formed in the inner surface of the fluid handling structure 12. The supply opening 34 is positioned towards the bottom of the inner surface and may be located below the bottom surface of the frustoconical shape. The supply opening 34 is located around the inner surface and is spaced apart from the path of the radiation beam B around the path of the radiation beam B.

[0058] The immersion liquid is recovered from the immersion space 11 through a recovery opening 25 in the bottom surface of the fluid handling structure 12. When the facing surface moves under the fluid handling structure 12, the meniscus 33 can migrate on the surface of the recovery opening 25 in the same direction as the movement of the facing surface. The recovery opening 25 can be made of a porous member. The immersion liquid can be recovered in a single phase. The immersion liquid can be recovered in a two-phase flow. The two-phase flow is received in a chamber 35 within the fluid handling structure 12, where the two-phase flow is separated into liquid and gas. The liquid and gas are recovered from the chamber 35 through separate channels 36 and 38.

[0059] The inner perimeter 39 of the bottom surface of the fluid handling structure 12 extends away from the inner surface into the immersion space 11 to form a plate 40. The inner perimeter 39 forms a small hole, the size of which can match the shape and size of the radiation beam B. The plate 40 can be used to isolate the immersion liquid on either side of the plate 40. The supplied immersion liquid flows inwardly towards the hole, passes through the inner hole, and then flows radially outwardly under the plate 40 towards the surrounding recovery opening 25.

[0060] The fluid handling structure 12 can be in two parts, as shown on the right side in Figure 2b : an inner part 12a and an outer part 12b. The inner part 12a and the outer part 12b can move relative to each other mainly in a plane parallel to the facing surface. The inner part 12a can have a supply opening 34 and the inner part 12a can have an overflow recovery device 24. The outer part 12b can have a plate 40 and a recovery opening 25. The inner part 12a can have an intermediate recovery device 42 for recovering the immersion liquid flowing between the inner part 12a and the outer part 12b.

[0061] Thus, Figure 2b two different versions of the fluid handling structure allow the meniscus 33 to move in the same direction as the substrate W, thereby enabling a faster scan speed and increased throughput of the lithographic apparatus. However, the migration speed of the meniscus 33 on the surface of the recovery opening 25 in the fluid handling structure 12 located on the left side of Figure 2b may be slower. Figure 2b The fluid handling structure 12 on the right side of

[0062] Figure 2c allows the meniscus 33 to move faster 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 device 42 to ensure that sufficient immersion liquid is provided between the inner part 12a and the outer part 12b to prevent contact between the inner part 12a and the outer part 12b. Figure 2a and / or 2b as described above. Figure 2c shown in Figure 2a and / or 2b have the same reference numerals for the same features.

[0063] The fluid handling structure 12 has an inner surface complementary to the conical surface of a frustum of a cone. The bottom surface of the fluid handling structure 12 is closer to the facing surface than the flat bottom surface of the frustum of a cone. The immersion liquid is transported to the immersion space 11 through an opening formed in the surface of the fluid handling structure 12. The immersion liquid can be supplied through a supply opening 34 in the inner surface of the fluid structure 12. Alternatively or additionally, the immersion liquid can be supplied through a supply opening 20 in the inner surface of the fluid structure 12. Alternatively or additionally, the immersion liquid is supplied through a lower supply opening 23. The immersion liquid can be recovered via a pumping member, for example, via a recovery opening 21 formed in the inner surface and / or an overflow recovery device 24 and / or one or more openings in the surface of the fluid handling structure 12 as described below.

[0064] Figure 2c Two different versions of the fluid handling structure 12 on the left and right sides pin the meniscus 33. Due to the fixed position of the recovery opening 32a, in Figure 2c the version of the fluid handling structure 12 on the right side can pin the meniscus 33 at a position substantially fixed relative to the final element 100. In Figure 2c the version of the fluid handling structure 12 on the left side can pin the meniscus 33 below the recovery opening 25, and thus the meniscus 33 can move along the length and / or width of the recovery opening 25.

[0065] As described above with respect to Figure 2b the inner periphery of the bottom surface of the fluid handling structure 12 can extend away from the inner surface into the immersion space 11 to form a plate 40, as shown on the left side. As described above, this can form small holes, and the immersion liquid can be isolated on either side, and / or the immersion liquid can flow inwardly towards the holes, through the inner holes, and then flow radially outwardly below the plate 40 towards the surrounding recovery opening 25. Although this feature is shown on the Figure 2c left side in

[0066] As shown in Figure 2cAs shown on the left side, the fluid handling system may include the above-described fluid handling structure 12 and another device 3000. The fluid handling structure 12 may have a pumping member (such as a recovery opening 25) and a liquid supply opening (such as a lower supply opening 23). It will be understood that the fluid handling structure 12 may include any configuration disclosed with respect to Figure 2a the left side of Figure 2a the right side of Figure 2b the left side of Figure 2b the right side of Figure 2c the right side of, or (as described below)

[0067] Another device 3000 may also be referred to as a droplet catcher. Another device 3000 is provided to reduce the presence of liquid on the surface of the substrate W after the fluid handling structure 12 has moved over the surface of the substrate W. Another device 3000 may include a liquid supply member 3010 and at least one pumping member 3020. The at least one pumping member 3020 may be formed in a shape that surrounds the at least one supply member 3010 in a plane. The at least one liquid supply member 3010 may be configured to supply additional liquid to a space 3110 located between at least a portion of another device 3000 and the surface of the substrate W. Another device 3000 may be configured to recover at least some of the liquid through the at least one pumping member 3020. Another device 3000 may be used to combine any liquid remaining on the surface of the substrate W with the liquid in the space 3110, and then use another device 3000 to pump the liquid, such that the amount of liquid remaining on the surface of the substrate W is reduced.

[0068] In Figure 2c it, another device 3000 is shown as a device separate from the fluid handling structure 12. Another device 3000 may be located near the fluid handling structure 12. Alternatively, another device 3000 may be a part of the fluid handling structure 12, i.e., integrally formed with the fluid handling structure 12.

[0069] Another device 3000 may be configured to supply liquid to the space 3110 that is separated from the liquid supplied by the fluid handling structure 12.

[0070] Additionally or alternatively, the fluid handling structure 12 may have as in Figure 2cThe components shown on the right side of. More specifically, 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), and the at least one liquid supply member, the two extraction members, and the two gas supply members are formed on the surface of the fluid handling structure 12. The gas supply opening 27a may be omitted, i.e., it is optional. The at least one liquid supply member may be the same as the lower supply opening 23 in the bottom surface of the fluid handling structure 12 described above, or the same as the supply opening 20 or the liquid supply opening 34 formed on the inner surface of the fluid handling structure 12 described on the left side of Figure 2b The liquid supply member, the extraction member, and the gas supply member may be formed on the surface of the fluid handling structure 12. Specifically, these components may be formed on the surface of the fluid handling structure 12 facing the substrate W, and the surface of the fluid handling structure 12 facing the substrate W is the bottom surface of the fluid handling structure 12.

[0071] At least one of the two extraction members may include a porous material 37 therein. The porous material 37 may be disposed within an opening (e.g., the recovery opening 32a) through which the fluid handling structure 12 extracts fluid from below the fluid handling structure 12 and may recover the immersion liquid in a single-phase flow. The other of the two extraction members (e.g., the recovery opening 32b) may recover the immersion liquid as a two-phase extractor. The porous material 37 does not need to be flush with the bottom surface of the fluid handling structure 12.

[0072] Specifically, the fluid handling structure 12 may include a liquid supply member (e.g., below the lower supply opening 23), wherein the first extraction member (e.g., the recovery opening 32a) is radially outside the liquid supply member, and the first gas supply member (e.g., the gas supply opening 27a) is radially outside the first extraction member, and the second extraction member (e.g., the recovery opening 32b) is radially outside the first gas supply member, and the second gas supply member (e.g., the gas supply opening 27b) is radially outside the second extraction member. And Figure 2a Similarly, additional openings may exist in the bottom surface of the fluid handling structure 12, such as openings leading to the atmosphere or a gas source or a vacuum, as described above (with respect to the fluid handling structure 12).

[0073] For example, at least one additional opening (not shown) may be provided in the bottom surface of the fluid handling structure 12. The additional opening is optional. The additional opening may be arranged between the first extraction member (e.g., the recovery opening 32a) and the first gas supply member (e.g., the gas supply opening 27a), as described in the above arrangement. Alternatively or additionally, the additional opening may be arranged between the second extraction member (e.g., the recovery opening 32b) and the second gas supply member (e.g., the gas supply opening 27b), as described in the above arrangement. The additional opening may be the same as the additional opening 50 described above.

[0074] Optionally, the fluid handling structure 12 includes a recess 29. The recess 29 may be provided between the recovery opening 32a and the recovery opening 32b, or between the gas supply opening 27a and the recovery opening 32b. The shape of the recess 29 may be uniform around the fluid handling structure 12 and may optionally include an inclined surface. In the case where the recess 29 is provided between the recovery opening 32a and the recovery opening 32b, the gas supply opening 27b may be provided on the inclined surface, as Figure 2c shown. In the case where the recess 29 is provided between the supply opening 27a and the recovery opening 32b, the gas supply opening 27b may be provided on a part of the inclined surface or the bottom surface 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 of the gas supplied by the gas supply member on the fluid below the fluid handling structure 12.

[0075] Figure 2d Two different versions of the fluid handling structure 12 are shown in its left half and right half. Figure 2d The fluid handling structure 12 in the left half has: a liquid injection buffer 41a for accommodating a buffer amount of immersion liquid; and a plurality of liquid injection holes 41 for delivering the immersion liquid from the liquid injection buffer to the space 11. Outside the liquid injection holes 41 are internal liquid recovery holes 43 for guiding the liquid to an internal recovery buffer 43a provided with a porous member. Outside the internal liquid recovery holes 43 is provided a connection with respect to Figure 2cA recess 29 similar to the described groove. Outside the recess 29, a gas guiding groove 44 is in the lower surface of the fluid processing structure 12, and an external recovery hole 44a leads into the gas guiding groove 44. The external recovery hole 44a guides a two-phase recovery flow to an external recovery buffer 44b which also has a porous member. The outermost is a gas seal hole 45 which communicates between a gas seal buffer volume 45a and the space below the fluid processing structure 12 to provide an air flow to hold the immersion liquid.

[0076] Figure 2d The right half of the fluid processing structure 12 has a liquid supply opening 20 on its inner inclined surface. On the bottom surface of the fluid processing structure 12 (from the inside to the outside), there are a pumping opening 25 having a porous member 37, a first air knife opening 26a, a second air knife opening 26b, and a third air knife opening 26c. Each of these openings leads to a groove in the bottom surface of the fluid processing structure 12 which provides a buffer volume. The outermost part of the fluid processing structure 12 is stepped to provide greater isolation between the fluid processing structure 12 and the substrate W.

[0077] Figures 2a to 2d Examples of different configurations that can be used as part of a fluid processing system are shown. It will be understood that the examples provided above refer to specific pumping and recovery members, but not necessarily to the exact types of pumping and / or recovery members used. In some cases, the same functional features can be provided while using different terms to indicate the location of the members. Examples of the pumping members mentioned above include a recovery opening 21, an overflow recovery port 24, a recovery opening 25 (possibly including a porous plate and / or a chamber 35), a gas recovery opening 28, a pinning opening 32, a recovery opening 32a, a recovery opening 32b, and / or an intermediate recovery device 42. Examples of the supply members mentioned above include a supply opening 20, a lower supply opening 23, an air knife opening 26, a gas supply opening 27a, a gas supply opening 27b, and / or a supply opening 34. Generally, the pumping members for pumping / recovering fluid, liquid, or gas can be interchanged with at least any one of the other examples used for pumping / recovering fluid, liquid, or gas respectively. Similarly, the supply members for supplying fluid, liquid, or gas can be interchanged with at least any one of the other examples used for supplying fluid, liquid, or gas respectively. The pumping members can pump / recover fluid, liquid, or gas from a space by being connected to a negative pressure device that sucks the fluid, liquid, or gas into the pumping members. The supply members can supply fluid, liquid, or gas to a space by being connected to a relevant supply device.

[0078] Figure 3depicts a fluid processing system that includes a fluid processing structure or a liquid confinement structure 12, a gas supply conduit 70, a fluid delivery conduit 80, and a bypass conduit 90. The liquid confinement structure 12 is configured to confine an immersion fluid in an immersion space 11 located between at least a portion of the liquid confinement structure 12 and the surface of a substrate. For example, the fluid processing system, and / or in particular the fluid processing structure or the liquid confinement structure 12 and the corresponding immersion space 11 may be as described in any one of the above references Figure 1 and Figures 2a to 2d as depicted.

[0079] The gas supply conduit 70 is in fluid communication with the liquid confinement structure 12. Specifically, the gas supply conduit 70 is configured to supply a fluid to the immersion space 11, such as a gas such as carbon dioxide. The gas supply conduit 70 has a flow controller 71 that is configured to control the supply of the fluid from the gas supply conduit 70. For example, the flow controller 71 may control the flow rate of the fluid through the gas supply conduit 70. The flow controller 71 is optionally a mass flow controller.

[0080] The fluid delivery conduit 80 is in fluid communication with the liquid confinement structure 12. Specifically, the fluid delivery conduit 80 is configured to deliver a fluid extracted from the immersion space 11, such as a gas. The fluid extracted from the immersion space 11 may be a gas, such as carbon dioxide. Specifically, the fluid extracted from the immersion space 11 is desirably the fluid supplied to the immersion space 11 by the gas supply conduit 70. The fluid delivery conduit 80 has a flowmeter for measuring the flow rate of the fluid in the fluid delivery conduit 80.

[0081] In production mode, the fluid provided by the flow controller 71 flows through the liquid confinement structure 12 to the fluid delivery conduit 80. In other words, in production mode, the gas supply conduit 70 supplies fluid to the immersion space 11, and the fluid delivery conduit 80 delivers the fluid from the immersion space 11. In production mode, the flowmeter 81 is used to measure the flow rate of the fluid flowing through the fluid delivery conduit 80. Thus, the flowmeter 81 can measure the flow rate of the fluid (e.g., gas and / or liquid) extracted from the immersion space 11 located between the liquid confinement structure 12 and the surface of the substrate. The flowmeter 81 is optionally a gas flowmeter. The flowmeter 81 is desirably configured to measure the flow rate of the fluid, and more desirably the flowmeter 81 is configured to measure the mass flow rate.

[0082] The performance of the fluid processing system may depend on the flow rate of the fluid flowing into, through, and / or out of the liquid confinement structure 12. Specifically, it may be beneficial to obtain an accurate measurement of the flow rate of the fluid supplied to the immersion space 11 and / or delivered from the immersion space 11.

[0083] To ensure that the flow measurement results of the flow controller 71 for the supplied fluid are correct, the fluid pressure located downstream of the flow controller 71 can be measured during normal operation. The geometry of this part of the system and the relationship between the pressure and the flow rate in this part of the system are relatively simple and may have a linear relationship. Therefore, the (multiple) pressure measurements can be used to determine whether the flow controller 71 is providing the flow rate of the fluid with a sufficient level of accuracy. However, the relationship between the pressure and the flow rate through the liquid restriction structure 12 is more complex. This is because the flow rate in this part of the system is determined not only by the geometry of the hardware but also by a variety of other factors, including the amount of fluid supplied to the immersion space 11, the gap between the liquid restriction structure 12 and the sample, and the contact angle of the sample. Therefore, it is impossible to very accurately determine any inaccuracies of the flowmeter 81 caused, for example, by drift over time by observing the changes in the pressure of the fluid delivery pipe system 80.

[0084] Therefore, a method is needed to check whether the flowmeter 81 is calibrated so that the flow rate of the fluid flowing through the fluid delivery pipe 80 is known with a sufficient level of accuracy. This can be achieved through the calibration mode of the fluid handling system.

[0085] In the calibration mode, the gas supply pipe 70 is in direct fluid communication with the fluid delivery pipe 80 via the bypass pipe 90. The bypass pipe 90 bypasses the liquid restriction structure 12. In other words, in the calibration mode, the gas supply pipe 70 supplies fluid to the bypass pipe 90 instead of to the immersion space 11. The bypass pipe 90 delivers the fluid from the gas supply pipe 70 to the fluid delivery pipe 80.

[0086] In the calibration mode, the fluid provided by the flow controller 71 flows directly through the bypass pipe 90 into the fluid delivery pipe 80. The calibration mode can calibrate the flowmeter 81 by comparing the flow rate of the fluid measured in the fluid delivery pipe 80 with the flow rate of the gas provided by the flow controller 71.

[0087] In the production mode, due to the complexity of the geometry and flow rate in the immersion space 11 defined by the liquid confinement structure 12 and the sample, it may not be possible to know the relationship between the flow rate of the fluid supplied by the flow controller 71 of the gas supply pipe 70 and the flow rate of the fluid measured by the flow meter 81 of the fluid delivery pipe 80. In the calibration mode, the fluid flowing from the gas supply pipe 70 to the fluid delivery pipe 80 bypasses the immersion space 11. The geometry and flow in the bypass pipe 90 are simpler than those in the immersion space 11. The bypass pipe 90 provides a direct flow path between the flow controller 71 and the flow meter 81, such that all the fluid from the flow controller 71 can be supplied to the flow meter 81 via the bypass pipe 90. In other words, in the calibration mode, there may be no flow outlet between the flow controller 71 and the flow meter 81 in the system. Therefore, the flow rate provided by the flow controller 71 and the flow rate measured by the flow meter 81 can be directly compared. In normal operation (e.g., production mode), this is not the case because the immersion space 11 is an open environment and the flow may leak or leave through other outlets, such that not all the fluid reaches the flow meter 81. Therefore, in the calibration mode, the relationship between the flow rate of the fluid supplied by the flow controller 71 of the gas supply pipe 70 and the flow rate of the fluid measured by the flow meter 81 of the fluid delivery pipe 80 can be known. Thus, if the flow controller 71 has been calibrated, it can be determined whether the flow meter 81 is calibrated in the calibration mode.

[0088] The fluid handling system may further include a comparator (not shown). In the calibration mode, the comparator can be configured to compare the flow rate of the fluid measured in the fluid delivery pipe 80 with the flow rate of the fluid provided by the flow controller 71. Specifically, the comparator can be configured to compare the flow rate measured by the flow meter 81 with the flow rate provided by the flow controller 71.

[0089] As described above, in the calibration mode, there may be a known relationship between the flow rate provided by the flow controller 71 and the flow rate flowing through the fluid delivery pipe 80. Therefore, for a given flow rate provided by the flow controller 71, the flow rate flowing through the fluid delivery pipe 80 can be predetermined (i.e., determined in advance). The predetermined flow rate flowing through the fluid delivery pipe 80 based on the known relationship can be compared with the flow rate flowing through the fluid delivery pipe 80 measured by the flow meter 81. If the predetermined flow rate flowing through the fluid delivery pipe 80 matches the flow rate measured by the flow meter 81 within a predetermined range, the flow meter 81 can be considered calibrated. In other words, it can be determined that the flow meter 81 is providing a sufficiently accurate measurement of the flow rate flowing through the fluid delivery pipe 80.

[0090] The fluid handling system may optionally further include an instrument calibration unit (not shown) configured to adjust the flow meter 81 based on the comparison. For example, if it is determined based on the comparison that the measured value of the flow meter 81 is lower than expected, the flow meter 81 may be adjusted such that the flow meter 81 gives an expected measured value. Alternatively or additionally, the fluid handling system may be configured to issue an alarm if the comparison shows that the predetermined flow rate through the fluid delivery pipe 80 does not match the flow rate measured by the flow meter 81 within a predetermined range. In other words, the fluid handling system may be configured to issue an alarm to the user if the flow meter 81 is not providing a sufficiently accurate measurement of the flow rate through the fluid delivery pipe 80. The user can then take measures to adjust or replace the flow meter 81 as needed.

[0091] The bypass pipe 90 may be configured such that, in the calibration mode, both the gas supply pipe 70 and the fluid delivery pipe 80 operate at a pressure similar to the pressure of the gas supply pipe 70 and the fluid delivery pipe 80 in the production mode, i.e., at a pressure within a certain threshold range. The bypass pipe 90 is desirably configured such that, in the calibration mode, the pressure at the flow controller 71 and the flow meter 81 is similar to the pressure at the flow controller 71 and the flow meter 81 in the production mode, i.e., within a certain threshold range of the pressure at the flow controller 71 and the flow meter 81 in the production mode. The bypass pipe 90 optionally includes, for example, a flow restricting device 94 as shown in Figure 3 The flow restricting device 94 may be configured to achieve a desired pressure level in the fluid delivery pipe 80 and / or the gas supply pipe 70 in the calibration mode.

[0092] The fluid handling system may include a bypass pipe 90. Alternatively, all or a part of the bypass pipe 90 may be removed from the system. In the calibration mode, the bypass pipe 90 is attached to the system, and in the production mode, the bypass pipe 90 is detached from the system. For example, the bypass pipe 90 may be configured to disconnect from the gas supply pipe 70 and the fluid delivery pipe 80 to set the system to the production mode. To set the fluid handling system to the calibration mode, the bypass pipe 90 may be connected to the system. In other words, to set the fluid handling system to the calibration mode, the bypass pipe 90 may be connected to the gas supply pipe 70 and the fluid delivery pipe 80. With this arrangement, the same bypass pipe 90 can be shared among multiple fluid handling systems by disconnecting the bypass pipe 90 from one system that has been calibrated and connecting it to another system that may need calibration. This is possible because the bypass pipe 90 is not used when the system is in the production mode. This can advantageously utilize the components of the bypass pipe 90 effectively, thus saving costs.

[0093] For example, as shown in Figure 3As shown, the fluid handling system may also include a plurality of valves. The plurality of valves may be configured to change the system between a production mode and a calibration mode. Alternatively or additionally, for an arrangement in which the bypass conduit 90 is removable, the plurality of valves may be configured to change the system between a production mode and a calibration mode, in which the bypass conduit 90 may be removed in the production mode without impeding the flow of fluid from the gas supply conduit 70 to the immersion space 11 and from the immersion space 11 through the fluid delivery conduit 80.

[0094] In Figure 3 the exemplary arrangement shown, the plurality of valves includes a gas supply valve 72, a bypass valve 92, and a fluid extraction valve 82.

[0095] The gas supply valve 72 is disposed in the gas supply conduit 70. The gas supply valve 72 is desirably disposed downstream of the flow controller 71 in the direction of flow of the fluid. In other words, the gas supply valve 72 may be configured to permit, restrict, and / or block the flow from the gas supply conduit 70 to the immersion space 11. Specifically, the gas supply valve 72 may be configured to permit, restrict, and / or block the flow of the fluid provided by the flow controller 71 to the immersion space 11. In the production mode, the gas supply valve 72 is opened to permit the flow of fluid from the gas supply conduit 70 into the immersion space 11. In the calibration mode, the gas supply valve 72 is closed to prevent the flow of fluid from the gas supply conduit 70 into the immersion space 11.

[0096] The bypass valve 92 is disposed in the bypass conduit 90. In other words, the bypass valve 92 may be configured to permit, restrict, and / or block the flow through the bypass conduit 90. In the production mode, the bypass valve 92 is closed to prevent the flow of fluid from the gas supply conduit 70 through the bypass conduit 90 to the fluid delivery conduit 80. In the calibration mode, the bypass valve 92 is opened to permit the flow of fluid from the gas supply conduit 70 through the bypass conduit 90 to the fluid delivery conduit 80.

[0097] The fluid extraction valve 82 may be disposed in the fluid delivery conduit 80 or may be disposed at the inlet of the fluid delivery conduit 80. The fluid extraction valve 82 is desirably disposed upstream of the flow meter 81. In other words, the fluid extraction valve 82 may be configured to permit, restrict, and / or block the flow of fluid from the immersion space 11 to the fluid delivery conduit 80. Specifically, the fluid extraction valve 82 may be configured to permit, restrict, and / or block the flow of fluid from the immersion space 11 to the flow meter 81. In the production mode, the fluid extraction valve 82 is opened to permit the flow of fluid from the immersion space 11 into the fluid delivery conduit 80. In the calibration mode, the fluid extraction valve 82 is closed to prevent the flow of fluid from the immersion space 11 into the fluid delivery conduit 80.

[0098] As Figure 3As shown in the exemplary arrangement, the fluid handling system may include a fluid extraction conduit 84 that is in fluid communication with the liquid confinement structure 12 and is configured to extract fluid from the immersion space 11 and direct the extracted fluid to a fluid delivery conduit 80. A fluid extraction valve 82 may be provided between the fluid extraction conduit 84 and the fluid delivery conduit 80. In other words, the fluid extraction valve 82 may be configured to permit, restrict, and / or prevent fluid flow from the fluid extraction conduit 84 into the fluid delivery conduit 80. Specifically, the fluid extraction valve 82 may be configured to permit, restrict, and / or prevent fluid flow from the fluid extraction conduit 84 to the flow meter 81. In production mode, the fluid extraction valve 82 is opened to permit fluid flow from the fluid extraction conduit 84 into the fluid delivery conduit 80. In calibration mode, the fluid extraction valve 82 is closed to prevent fluid flow from the fluid extraction conduit 84 into the fluid delivery conduit 80.

[0099] At least in production mode, the immersion liquid is also supplied to the immersion space 11 from liquid supply openings (e.g., Figures 2a to 2d 20, 23, 34 in), such that the fluid extraction conduit 84 extracts a two-phase fluid, i.e., a mixture of gas (such as CO2) and liquid (such as water). Figure 3The liquid supply and extraction circuit is not shown. In this arrangement, the two-phase fluid can be separated before the two-phase fluid reaches the flowmeter 81, such that the flowmeter 81 measures only a single phase (e.g., gas). Specifically, the separated phase of the fluid (e.g., liquid) can be directed through a branch or outlet (not shown) located between the immersion space 11 and the flowmeter 81. Optionally, the separated phase of the fluid can be directed through a branch or outlet provided at a location between the fluid extraction pipe 84 and the flowmeter 81, which is desirably provided at a location between the fluid extraction pipe 84 and the bypass pipe 90 or the location where the first branch 93 of the bypass pipe 90 is connected to the fluid delivery pipe 80, and more desirably provided at a location between the fluid extraction pipe 84 and the fluid extraction valve 82, i.e., upstream of the above location or the fluid extraction valve 82. Similarly, for the additional fluid delivery pipe 85, a single phase of the two-phase fluid can be extracted before the fluid reaches the additional flowmeter 86. The separated phase of the fluid (e.g., liquid) can be directed through a branch or outlet (not shown) located between the immersion space 11 and the additional flowmeter 86. Optionally, the separated phase of the fluid can be directed through a branch or outlet provided at a location between the fluid extraction pipe 84 and the additional flowmeter 86, desirably, the branch or outlet is provided at a location between the fluid extraction pipe 84 and the additional bypass pipe 95 or the location where the second branch 98 of the bypass pipe is connected to the additional fluid delivery pipe 85, and more desirably, the branch or outlet is provided at a location between the fluid extraction pipe 84 and the additional fluid extraction valve 87, i.e., upstream of the above location or the additional fluid extraction valve 87.

[0100] In an alternative arrangement ( Figure 3 not shown), the fluid processing system can include a plurality of fluid extraction pipes 84 that are in fluid communication with the liquid confinement structure 12 and are configured to extract fluid from the immersion space 11 and direct the extracted fluid to the fluid delivery pipe 80. The plurality of fluid extraction pipes 84 optionally merge downstream of the immersion space 11 to form the fluid delivery pipe 80. In this arrangement, a single fluid extraction valve 82 can be provided at the inlet of the fluid delivery pipe 80 upstream of the flowmeter 81 or at a point along the fluid delivery pipe 80. Alternatively, two fluid extraction valves 82 can be provided at a point along the fluid extraction pipe 84.

[0101] As Figure 4 and Figure 5As shown in the exemplary arrangement, the fluid processing system may optionally further include an additional fluid delivery conduit 85 that is in fluid communication with the fluid processing structure or the liquid confinement structure 12 and is configured to convey fluid withdrawn from the immersion space 11. The additional fluid delivery conduit 85 is provided with an additional flowmeter 86 that is configured to measure the flow rate of the fluid in the additional fluid delivery conduit 85. Specifically, the fluid in the additional fluid delivery conduit 85 may be the fluid supplied to the immersion space 11 via the gas supply conduit 70.

[0102] The fluid delivery conduit 80 and the additional fluid delivery conduit 85 may be respectively configured to convey fluid from the immersion space 11. As Figure 4 and Figure 5 shown, the fluid processing system may include a fluid extraction conduit 84. The first fluid extraction conduit 84 is in fluid communication with the liquid confinement structure 12 and is configured to extract fluid from the immersion space 11 and direct the extracted fluid to the fluid delivery conduit 80. The second fluid extraction conduit 84 is in fluid communication with the liquid confinement structure 12 and is configured to extract fluid from the immersion space 11 and direct the extracted fluid to the additional fluid delivery conduit 85. In an alternative arrangement (not shown), the fluid delivery conduit 80 and the additional fluid delivery conduit 85 may be respectively configured to directly extract fluid from the immersion space 11.

[0103] Figure 4 An exemplary fluid processing system is shown that includes a gas supply conduit 70, a plurality of fluid delivery conduits 80, 85, and corresponding bypass conduits 90, 95. Each bypass conduit 90, 95 is configured such that in a calibration mode, the gas supply conduit 70 is in direct fluid communication with one of the plurality of fluid delivery conduits 80, 85 via the corresponding bypass conduit 90, 95.

[0104] Unless otherwise specified, Figure 4 the components with the corresponding reference numerals in Figure 3 perform the same functions as the components described above with respect to Figure 3 . Similar to the above Figure 4 arrangement, in the

[0105] arrangement in the calibration mode, the gas supply conduit 70 is in direct fluid communication with the fluid delivery conduit 80 via the bypass conduit 90, where the bypass conduit 90 bypasses the liquid confinement structure 12 and the additional bypass conduit 95. The fluid supplied by the flow controller 71 flows directly through the bypass conduit 90 to the fluid delivery conduit 80. Figure 4In the arrangement, in an additional calibration mode, the gas supply pipe 70 is in direct fluid communication with an additional fluid delivery pipe 85 through an additional bypass pipe 95, wherein the additional bypass pipe 95 bypasses the liquid restriction structure 12 and the bypass pipe 90. The gas supplied by the flow controller 71 flows directly through the additional bypass pipe 95 into the additional fluid delivery pipe 85.

[0106] For example, as Figure 4 shown, the fluid handling system may further include a plurality of valves. Similar to Figure 3 the exemplary arrangement shown in Figure 4 , the plurality of valves include a gas supply valve 72, a bypass valve 92, and a fluid extraction valve 82, and the gas supply valve 72, the bypass valve 92, and the fluid extraction valve 82 are respectively configured to be the same as the situations described above for Figure 3 . Figure 4 The plurality of valves in

[0107] also include an additional bypass valve 97 and an additional fluid extraction valve 87. The additional bypass valve 97 is disposed in the additional bypass pipe 95. In other words, the additional bypass valve 97 may be configured to allow, restrict, and / or block the flow through the additional bypass pipe 95. In the production mode, the bypass valve 97 is closed to prevent fluid from flowing from the gas supply pipe 70 to the additional fluid delivery pipe 85 via the additional bypass pipe 95. In the calibration mode, the additional bypass valve 97 is closed to prevent fluid from flowing from the gas supply pipe 70 to the additional fluid delivery pipe 85 via the additional bypass pipe 95. In the additional calibration mode, the bypass valve 92 is closed to prevent fluid from flowing from the gas supply pipe 70 to the fluid delivery pipe 80 via the bypass pipe 90. In the additional calibration mode, the additional bypass valve 97 is opened to allow fluid to flow from the gas supply pipe 70 to the additional fluid delivery pipe 85 via the additional bypass pipe 95.

[0108] An additional fluid extraction valve 87 may be provided in an additional fluid delivery conduit 85 or at an inlet of the additional fluid delivery conduit 85. The additional fluid extraction valve 87 is desirably provided upstream of an additional flow meter 86. In other words, the additional fluid extraction valve 87 may be configured to permit, restrict, and / or block flow from the immersion space 11 to the additional fluid delivery conduit 85. Specifically, the additional fluid extraction valve 87 may be configured to permit, restrict, and / or block flow from the immersion space 11 to the additional flow meter 86. In production mode, the additional fluid extraction valve 87 is opened to permit fluid to flow from the immersion space 11 into the additional fluid delivery conduit 85. In an additional calibration mode, the additional fluid extraction valve 87 is closed to prevent fluid from flowing from the immersion space 11 into the additional fluid delivery conduit 85. In the additional calibration mode, the fluid extraction valve 82 is closed to prevent fluid from flowing from the immersion space 11 into the additional fluid delivery conduit 85.

[0109] As Figure 5 shown in the exemplary arrangement of, the fluid processing system may include an additional fluid extraction conduit 84 that is in fluid communication with the liquid confinement structure 12 and is configured to extract fluid from the space 11 and direct the extracted fluid to the additional fluid delivery conduit 85. The additional fluid extraction valve 87 may be provided between the fluid extraction conduit 84 and the additional fluid delivery conduit 85. In other words, the additional fluid extraction valve 87 may be configured to permit, restrict, and / or block fluid flow from the fluid extraction conduit 84 to the additional fluid delivery conduit 85. Specifically, the additional fluid extraction valve 87 may be configured to permit, restrict, and / or block fluid flow from the fluid extraction conduit 84 to the additional flow meter 86. In production mode, the additional fluid extraction valve 87 is opened to permit fluid to flow from the fluid extraction conduit 84 into the additional fluid delivery conduit 85. In calibration mode, the additional fluid extraction valve 87 is closed to prevent fluid from flowing from the fluid extraction conduit 84 into the additional fluid delivery conduit 85. In the additional calibration mode, the additional fluid extraction valve 87 is closed to prevent fluid from flowing from the fluid extraction conduit 84 into the additional fluid delivery conduit 85. In the additional calibration mode, the fluid extraction valve 82 is closed to prevent fluid from flowing from the fluid extraction conduit 84 into the fluid delivery conduit 80.

[0110] Figure 5 depicts a preferred arrangement in which the fluid processing system includes a gas supply conduit 70, a plurality of fluid delivery conduits 80, 85, and a bypass conduit 90. In Figure 5In the arrangement, the bypass conduit 90 is configured such that in a calibration mode, the gas supply conduit 70 is in direct fluid communication with one of the plurality of fluid delivery conduits 80, 85 via the bypass conduit 90. The bypass conduit 90 may include a first branch 93 configured to provide fluid communication between the gas supply conduit 70 and the fluid delivery conduit 80. The bypass conduit 90 may include a second branch 98 configured to provide fluid communication between the gas supply conduit 70 and an additional fluid delivery conduit 85.

[0111] In the calibration mode, the gas supply conduit 70 is in direct fluid communication with the fluid delivery conduit 80 via the first branch 93 of the bypass conduit 90, wherein the first branch 93 of the bypass conduit 90 bypasses the fluid handling structure or liquid restriction structure 12 and the second branch 98 of the bypass conduit 90. The fluid supplied by the flow controller 71 flows directly through the bypass conduit 90 to the fluid delivery conduit 80.

[0112] In Figure 5 When the arrangement is in an additional calibration mode, the gas supply conduit 70 is in direct fluid communication with the additional fluid delivery conduit 85 via the second branch 98 of the bypass conduit 90, wherein the second branch 98 of the bypass conduit 90 bypasses the liquid restriction structure 12 and the first branch 93 of the bypass conduit 90. The fluid supplied by the flow controller 71 flows directly through the bypass conduit 90 to the additional fluid delivery conduit 85.

[0113] For example, as Figure 5 shown, the fluid handling system may further include a plurality of valves. Similar to the exemplary arrangement Figure 4 shown, Figure 5 the plurality of valves in Figure 4 include a gas supply valve 72, a bypass valve 92, a fluid extraction valve 82, and an additional fluid extraction valve 87, and the gas supply valve 72, the bypass valve 92, the fluid extraction valve 82, and the additional fluid extraction valve 87 are configured as described above for Figure 5 The plurality of valves in Figure 5 also include a second branch bypass valve 99. In the arrangement

[0114] The second branch bypass valve 99 is disposed in the second branch 98 of the bypass conduit 90. In other words, the second branch bypass valve 99 may be configured to permit, restrict, and / or block flow through the second branch 98 of the bypass conduit 90. In the production mode, the second branch bypass valve 99 is closed to prevent fluid from flowing from the gas supply conduit 70 through the second branch 98 of the bypass conduit 90 to the additional fluid delivery conduit 85. In the calibration mode, the second branch bypass valve 99 is closed to prevent fluid from flowing from the gas supply conduit 70 through the second branch 98 of the bypass conduit 90 to the additional fluid delivery conduit 85. In an additional calibration mode, the bypass valve 92 is closed to prevent fluid from flowing from the gas supply conduit 70 through the bypass conduit 90 to the fluid delivery conduit 80. In an additional calibration mode, the second branch bypass valve 99 is opened to permit fluid from the gas supply conduit 70 to flow through the second branch 98 of the bypass conduit 90 to the additional fluid delivery conduit 85.

[0115] The fluid processing system may also include a comparator (not shown). In an additional calibration mode, the comparator may be configured to compare the flow rate of the fluid measured in the additional fluid delivery conduit 85 with the flow rate of the fluid provided by the flow controller 71. Specifically, the comparator may be configured to compare the flow rate measured by the additional flow meter 86 with the flow rate provided by the flow controller 71.

[0116] The fluid processing system optionally further includes an instrument calibration unit (not shown) configured to adjust the additional flow meter 86 based on the comparison. For example, if it is determined based on the comparison that the measurement of the additional flow meter 86 is lower than expected, the additional flow meter 86 may be adjusted such that the additional flow meter 86 gives an expected measurement value. Alternatively or additionally, the fluid processing system may be configured to issue an alarm if the comparison indicates that the predetermined flow rate flowing through the additional fluid delivery conduit 85 does not match the flow rate measured by the additional flow meter 86 within a predetermined range based on the flow rate provided by the flow controller 71 in the additional calibration mode. In other words, the fluid processing system may be configured to issue an alarm to the user if the additional flow meter 86 is not providing a sufficiently accurate measurement of the flow rate flowing through the additional fluid delivery conduit 85. The user can then take measures to adjust or replace the additional flow meter 86 as needed.

[0117] The fluid processing system optionally includes a pressure sensor 73. The pressure sensor 73 may be disposed downstream of the flow controller 71, such as as Figure 3 、 Figure 4 and Figure 5 shown. The pressure sensor 73 is configured to measure the pressure of the fluid. The pressure sensor 73 is desirably disposed in the gas supply conduit 70, as Figure 3As shown. The pressure sensor 73 is desirably capable of determining the relationship between the pressure and the flow rate in the gas flow conduit 70 in order to calibrate the flow controller 71. Thus, the pressure sensor 73 can be used to calibrate the flow controller 71. Then, the flow controller 71 can be used to calibrate the flowmeter 81, for example, by setting the fluid processing system in the calibration mode as described above.

[0118] The fluid processing system optionally further includes a supply calibration unit (not shown) that is configured to adjust the flow controller 71 based on a comparison between the pressure measured by the pressure sensor 73 and the flow rate set by the flow controller 71. In other words, if the pressure measured by the pressure sensor 73 based on the flow rate set by the flow controller 71 is not within an acceptable range of the expected pressure, the supply calibration unit can be configured to automatically adjust the flow controller 71, as this would indicate that the flow controller 71 has drifted out of calibration. Thus, the supply calibration unit can be used to automatically calibrate the flow controller 71. Alternatively or additionally, the fluid processing system can include an alarm unit that is configured to alert the user if the pressure measured by the pressure sensor 73 based on the flow rate set by the flow controller 71 is not within an acceptable range of the expected pressure. In this way, the user can manually take measures as needed to adjust or replace the flow controller 71.

[0119] Although Figure 4 and Figure 5 the arrangements shown respectively include only one additional fluid delivery conduit 85, the arrangements can be modified to include more than one additional fluid delivery conduit.

[0120] The present invention can provide a lithographic apparatus. The lithographic apparatus can have any / all other features or components of the above-described lithographic apparatus. For example, the lithographic apparatus can optionally include at least one or more of a light source SO, an illumination system IL, a projection system PS, a substrate support WT, etc.

[0121] Specifically, the lithographic apparatus can include a projection system PS that is configured to project a radiation beam B onto an area of the surface of a substrate W.

[0122] Although the application of the lithographic apparatus in integrated circuit manufacturing may be specifically mentioned herein, it should be understood that the lithographic apparatus described herein may have other applications. Other possible applications include manufacturing integrated optical systems, guiding and detecting patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0123] Where context allows, embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented by 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, a machine-readable medium 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.). Further, firmware, software, routines, instructions may be described herein as performing certain operations. However, it should be understood that such descriptions are for convenience only and these operations are actually performed by computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc., and may cause actuators or other devices to interact with the physical world when performing these operations.

[0124] Although embodiments of the invention may be specifically mentioned herein in the context of a lithographic apparatus, embodiments of the invention may also be used in other devices. Embodiments of the invention may form part of a mask inspection device, a metrology device, or any device for measuring or processing an object such as a wafer (or other substrate) or a mask (or other patterning device). Such devices may generally be referred to as lithographic tools. Such lithographic tools may use ambient (non-vacuum) conditions.

[0125] Although the above may have specifically referred to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that, where context allows, the invention is not limited to optical lithography.

[0126] Embodiments include the following numbered aspects:

[0127] 1. A fluid handling system, comprising:

[0128] A liquid confinement structure configured to confine an immersion fluid in a space between at least a portion of the liquid confinement structure and a surface of a substrate;

[0129] A gas supply conduit in fluid communication with the liquid confinement structure and configured to supply fluid to the space, the gas supply conduit having a flow controller configured to control the supply of gas from the gas supply conduit;

[0130] A fluid delivery conduit that is in fluid communication with the liquid confinement structure and configured to deliver fluid withdrawn from the space, the fluid delivery conduit having a flow meter configured to measure the flow rate of gas in the fluid delivery conduit; and

[0131] wherein, in a calibration mode,

[0132] the gas supply conduit is in direct fluid communication with the fluid delivery conduit via a bypass conduit, wherein the bypass conduit bypasses the liquid confinement structure; and

[0133] gas supplied by the flow controller flows directly through the bypass conduit into the fluid delivery conduit.

[0134] 2. The system according to aspect 1, further comprising a comparator, wherein, in the calibration mode, the comparator is configured to compare the measured flow rate of gas in the fluid delivery conduit with the flow rate of gas supplied by the flow controller.

[0135] 3. The system according to aspect 2, further comprising an instrument calibration unit configured to adjust the flow meter based on the comparison.

[0136] 4. The system according to any of the preceding aspects, wherein all or a portion of the bypass conduit can be removed from the system, and wherein, in the calibration mode, the bypass conduit is attached to the system.

[0137] 5. The system according to any of the preceding aspects, wherein, in a production mode, gas supplied by the flow controller flows through the liquid confinement structure into the fluid delivery conduit such that the flow meter is configured to measure the flow rate of the withdrawn gas.

[0138] 6. The system according to aspect 5, wherein all or a portion of the bypass conduit can be removed from the system, and wherein, in the calibration mode, the bypass conduit is attached to the system while in the production mode the bypass conduit is detached from the system.

[0139] 7. The system according to aspect 5 or 6, further comprising a plurality of valves configured to change the system between the production mode and the calibration mode.

[0140] 8. The system according to aspect 7, wherein the plurality of valves includes:

[0141] a gas supply valve disposed in the gas supply conduit downstream of the flow controller;

[0142] Wherein, in the production mode, the gas supply valve is opened to allow gas to flow from the gas supply pipeline into the space; and

[0143] Wherein, in the calibration mode, the gas supply valve is closed to prevent gas from flowing from the gas supply pipeline into the space.

[0144] 9. The system according to aspect 7 or 8, wherein the plurality of valves includes:

[0145] A bypass valve disposed in the bypass pipeline;

[0146] Wherein, in the production mode, the bypass valve is closed to prevent gas from flowing from the gas supply pipeline through the bypass pipeline into the fluid delivery pipeline; and

[0147] Wherein, in the calibration mode, the bypass valve is opened to allow gas to flow from the gas supply pipeline through the bypass pipeline into the fluid delivery pipeline.

[0148] 10. The system according to any one of aspects 7 to 9, wherein the plurality of valves includes:

[0149] A fluid extraction valve disposed in the fluid delivery pipeline upstream of the flowmeter;

[0150] Wherein, in the production mode, the fluid extraction valve is opened to allow gas to flow from the space into the fluid delivery pipeline; and

[0151] Wherein, in the calibration mode, the fluid extraction valve is closed to prevent gas from flowing from the space into the fluid delivery pipeline.

[0152] 11. The system according to any one of the foregoing aspects, further comprising a plurality of fluid extraction pipelines that are in fluid communication with the liquid restriction structure and are configured to extract fluid from the space and direct the extracted fluid to the fluid delivery pipeline.

[0153] 12. The system according to aspect 11, wherein the plurality of fluid extraction pipelines merge downstream of the space to form the fluid delivery pipeline.

[0154] 13. The system according to any one of aspects 1 to 10, further comprising an additional fluid delivery pipeline that is in fluid communication with the liquid restriction structure and is configured to convey the fluid extracted from the space, the additional fluid delivery pipeline having an additional flowmeter configured to measure the flow rate of gas in the additional fluid delivery pipeline.

[0155] 14. The system according to aspect 13, wherein the fluid delivery pipe and the additional fluid delivery pipe are respectively configured to extract fluid from the space.

[0156] 15. The system according to aspect 13 or 14, wherein in an additional calibration mode,

[0157] the gas supply pipe is in direct fluid communication with the additional fluid delivery pipe via the bypass pipe, wherein the bypass pipe bypasses the liquid restriction structure; and

[0158] the gas supplied by the flow controller flows directly through the bypass pipe to the additional fluid delivery pipe.

[0159] 16. The system according to aspect 13 or 14, wherein in an additional calibration mode,

[0160] the gas supply pipe is in direct fluid communication with the additional fluid delivery pipe via the additional bypass pipe, wherein the additional bypass pipe bypasses the liquid restriction structure and the bypass pipe; and

[0161] the gas supplied by the flow controller flows directly through the additional bypass pipe to the additional fluid delivery pipe.

[0162] 17. The system according to aspect 15 or 16, further comprising a comparator, wherein in an additional calibration mode, the comparator is configured to compare the measured flow rate of the gas in the additional fluid delivery pipe with the flow rate of the gas supplied by the flow controller.

[0163] 18. The system according to any one of the preceding aspects, further comprising a pressure sensor disposed downstream of the flow controller, wherein the pressure sensor is configured to measure the pressure of the gas in the gas supply pipe.

[0164] 19. The system according to aspect 18, further comprising a supply calibration unit configured to adjust the flow controller based on a comparison of the pressure measured by the pressure sensor with the flow rate set by the flow controller.

[0165] 20. The system according to any one of the preceding aspects, wherein the bypass pipe includes a flow restrictor.

[0166] 21. A method for calibrating a flow meter in a fluid processing system,

[0167] the fluid processing system comprising:

[0168] A liquid confinement structure configured to confine an immersion fluid in a space between at least a portion of the liquid confinement structure and a surface of a substrate;

[0169] A gas supply conduit in fluid communication with the liquid confinement structure and configured to supply fluid to the space, the gas supply conduit having a flow controller configured to control the supply of gas from the gas supply conduit;

[0170] A fluid delivery conduit in fluid communication with the liquid confinement structure and configured to draw fluid from the space, the fluid delivery conduit having a flow meter configured to measure the flow rate of gas in the fluid delivery conduit;

[0171] The method includes:

[0172] Setting the system to a calibration mode in which:

[0173] The gas supply conduit is in direct fluid communication with the fluid delivery conduit via a bypass conduit that bypasses the liquid confinement structure, and the gas supplied by the flow controller flows directly through the bypass conduit into the fluid delivery conduit; and comparing the measured flow rate of gas in the fluid delivery conduit with the flow rate of gas supplied by the flow controller.

[0174] While specific embodiments of the invention have been described above, it will be apparent that the invention may be practiced in ways other than those described above. The foregoing description is intended to be illustrative, not limiting. Thus, it will be apparent to those skilled in the art that the invention as described above may be modified without departing from the scope of the claims set forth below.

Claims

1. A fluid processing system, comprising: A liquid confinement structure configured to confine an immersion fluid in a space between at least a portion of the liquid confinement structure and a surface of a substrate; A gas supply conduit in fluid communication with the liquid confinement structure and configured to supply fluid to the space, the gas supply conduit having a flow controller configured to control the supply of gas from the gas supply conduit; A fluid delivery conduit in fluid communication with the liquid confinement structure and configured to deliver fluid withdrawn from the space, the fluid delivery conduit having a flow meter configured to measure the flow rate of gas in the fluid delivery conduit; and Wherein, in a calibration mode: The gas supply conduit is in direct fluid communication with the fluid delivery conduit via a bypass conduit, wherein the bypass conduit bypasses the liquid confinement structure; and The gas supplied by the flow controller flows directly into the fluid delivery conduit via the bypass conduit.

2. The system according to claim 1, further comprising a comparator, wherein, In the calibration mode, the comparator is configured to compare the measured flow rate of gas in the fluid delivery conduit with the flow rate of gas supplied by the flow controller.

3. The system of claim 2, further comprising an instrument calibration unit configured to adjust the flow meter based on the comparison.

4. The system according to any one of the preceding claims, wherein, All or a portion of the bypass conduit can be removed from the system, and wherein, in the calibration mode, the bypass conduit is attached to the system, and / or wherein, in the production mode, the gas supplied by the flow controller flows through the liquid confinement structure into the fluid delivery conduit such that the flow meter is configured to measure the flow rate of the withdrawn gas.

5. The system according to claim 4, wherein All or a portion of the bypass conduit can be removed from the system, and wherein, in the calibration mode, the bypass conduit is attached to the system, and in the production mode, the bypass conduit is separated from the system.

6. The system of claim 4, further comprising a plurality of valves configured to change the system between a production mode and a calibration mode.

7. The system according to claim 6, wherein, The plurality of valves includes: A gas supply valve disposed in the gas supply conduit downstream of the flow controller; Wherein, in the production mode, the gas supply valve is opened to allow gas to flow from the gas supply conduit into the space; and Wherein, in the calibration mode, the gas supply valve is closed to prevent gas from flowing from the gas supply conduit into the space, and / or Wherein, the plurality of valves includes: A bypass valve disposed in the bypass conduit; Wherein, in the production mode, the bypass valve is closed to prevent gas from flowing from the gas supply conduit through the bypass conduit into the fluid delivery conduit; and Wherein, in the calibration mode, the bypass valve is opened to allow gas to flow from the gas supply conduit through the bypass conduit into the fluid delivery conduit, and / or Wherein, the plurality of valves includes: A fluid extraction valve disposed in the fluid delivery pipe upstream of the flow meter; wherein, in the production mode, the fluid extraction valve is opened to allow gas to flow from the space into the fluid delivery pipe; and wherein, in the calibration mode, the fluid extraction valve is closed to prevent gas from flowing from the space into the fluid delivery pipe.

8. The system according to any one of the preceding claims, the system further comprising a plurality of fluid extraction pipes that are in fluid communication with the liquid confinement structure and are configured to extract fluid from the space and direct the extracted fluid to the fluid delivery pipe, or the system further comprising an additional fluid delivery pipe that is in fluid communication with the liquid confinement structure and is configured to convey the fluid extracted from the space, the additional fluid delivery pipe having an additional flow meter configured to measure the flow rate of gas in the additional fluid delivery pipe.

9. The system according to claim 8, wherein The plurality of fluid extraction pipes merge downstream of the space to form the fluid delivery pipe, or wherein, the fluid delivery pipe and the additional fluid delivery pipe are each configured to extract fluid from the space.

10. The system according to claim 8 or 9, wherein, In an additional calibration mode, the gas supply pipe is in direct fluid communication with the additional fluid delivery pipe via the bypass pipe, wherein the bypass pipe bypasses the liquid confinement structure; and the gas supplied by the flow controller flows directly into the additional fluid delivery pipe via the bypass pipe, or wherein, in an additional calibration mode, the gas supply pipe is in direct fluid communication with the additional fluid delivery pipe via the additional bypass pipe, wherein the additional bypass pipe bypasses the liquid confinement structure and the bypass pipe; and the gas supplied by the flow controller flows directly into the additional fluid delivery pipe via the additional bypass pipe.

11. The system according to claim 10, further comprising a comparator, wherein, In an additional calibration mode, the comparator is configured to compare the measured flow rate of gas in the additional fluid delivery pipe with the flow rate of gas supplied by the flow controller.

12. The system according to any one of the preceding claims, further comprising a pressure sensor disposed downstream of the flow controller, wherein, The pressure sensor is configured to measure the pressure of the gas in the gas supply pipe.

13. The system according to claim 12, further comprising a supply calibration unit configured to adjust the flow controller based on a comparison of the pressure measured by the pressure sensor and the flow rate set by the flow controller.

14. The system according to any one of the preceding claims, wherein, The bypass pipe includes a flow restrictor.

15. A method for calibrating a flow meter in a fluid processing system, the fluid processing system comprising: a liquid confinement structure configured to confine an immersion fluid in a space between at least a portion of the liquid confinement structure and a surface of a substrate; a gas supply pipe in fluid communication with the liquid confinement structure and configured to supply fluid to the space, the gas supply pipe having a flow controller configured to control the supply of gas from the gas supply pipe; A fluid delivery pipe, the fluid delivery pipe being in fluid communication with the liquid confinement structure and configured to extract fluid from the space, the fluid delivery pipe having a flow meter configured to measure the flow rate of the gas in the fluid delivery pipe; The method includes: Setting the system to a calibration mode, in which: The gas supply pipe is in direct fluid communication with the fluid delivery pipe via a bypass pipe, wherein the bypass pipe bypasses the liquid confinement structure, and The gas supplied by the flow controller flows directly through the bypass pipe into the fluid delivery pipe; and Comparing the measured flow rate of the gas in the fluid delivery pipe with the flow rate of the gas supplied by the flow controller.

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