Gas supply module, fluid processing system, lithographic apparatus and apparatus manufacturing method

Abstract

A gas supply module for a fluid treatment system in a lithographic apparatus, the gas supply system comprising: a humidifier having a humidifier input and a humidifier output; a first conduit configured to direct gas to the humidifier input; a second conduit configured to supply a humidified gas to the fluid treatment system; a control valve configured to control a gas flow in one of the first conduit and the second conduit; a measurement system configured to measure a pressure downstream of the control valve and generate a control signal; wherein the control valve maintains a constant pressure in one of the first conduit and the second conduit in response to the control signal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from European application No. 23156328.9 filed on February 13, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a gas supply module, a fluid processing system, a photolithography device and a device manufacturing method. Background Art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern to a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). For example, a lithographic apparatus can project a pattern (often also referred to as a "design layout" or "design") of a patterning device (e.g., a mask) 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 to the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern by a radiation beam in a given direction ("scanning" direction) while synchronously scanning the substrate in parallel or antiparallel to the given direction.

[0005] As semiconductor manufacturing processes continue to advance, the size of circuit elements has been continuously reduced, while the number of functional elements (such as transistors) per device has been steadily increasing for decades, following a trend commonly referred to as "Moore's Law". In order to keep up with Moore's Law, the semiconductor industry is pursuing technologies that can produce smaller and smaller features. In order to project a pattern onto a substrate, a lithography apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features patterned on the substrate. Typical wavelengths currently used are 365nm (i-line), 248nm, 193nm, and 13.5nm.

[0006] Further improvements in the resolution of smaller features can be achieved by providing an immersion fluid with a relatively high refractive index, such as water, on the substrate during exposure. The effect of the immersion fluid is to enable imaging of smaller features, as the exposure radiation will have a shorter wavelength in the fluid than in the gas. The effect of the immersion fluid can also be seen as increasing the effective numerical aperture (NA) of the system and also increasing the depth of focus.

[0007] The immersion fluid may be confined to a localized region between the projection system and the substrate of the lithographic apparatus by the fluid handling structure.

[0008] In an immersion lithography apparatus, gas flow can be used to control the immersion fluid. For example, a gas knife can be used to confine the immersion liquid to the space between the final element of the projection system and the substrate or substrate holder. The effectiveness of the gas knife may depend on precise control of the gas flow. Control of the gas flow is typically performed using a mass flow controller or mass flow meter. However, it has been found that mass flow controllers and mass flow meters are susceptible to drift and lose accuracy over time. Therefore, mass flow controllers and mass flow meters used in lithography apparatus must be periodically replaced and / or recalibrated in order to maintain the desired level of accuracy of the gas flow in the apparatus. Summary of the Invention

[0009] It is an object of the present invention to provide a gas flow control system with improved long term stability.

[0010] According to a first aspect of the present invention, there is provided a gas supply module for a fluid handling system in a lithographic apparatus, the gas supply system comprising:

[0011] a humidifier having a humidifier input and a humidifier output;

[0012] a first conduit configured to direct gas to a humidifier input;

[0013] a second conduit configured to supply humidified gas to the fluid handling system;

[0014] a control valve configured to control a flow of gas in one of the first conduit and the second conduit;

[0015] a measurement system configured to measure pressure downstream of the control valve and generate a control signal;

[0016] The control valve maintains a constant pressure in the one of the first conduit and the second conduit in response to the control signal.

[0017] According to a second aspect of the present invention, there is provided a gas supply module for a fluid handling system in a lithographic apparatus, the gas supply system comprising:

[0018] a humidifier having a humidifier input and a humidifier output;

[0019] a first conduit configured to direct gas to a humidifier input;

[0020] a second conduit configured to supply humidified gas to the fluid handling system;

[0021] a control valve configured to control a flow of gas in one of the first conduit and the second conduit;

[0022] A feedback system is connected to the sensor downstream of the control valve and is configured to maintain a constant flow in the second conduit.

[0023] According to a third aspect of the present invention, a lithography apparatus including the gas supply module is provided.

[0024] According to a fourth aspect of the present invention, there is provided a device manufacturing method, the device manufacturing method comprising:

[0025] confining the liquid to a space between the projection system and the substrate using a gas seal, the gas seal being supplied with gas from a gas supply module;

[0026] projecting a patterned beam of radiation through the liquid onto the substrate using a projection system;

[0027] measuring pressure at a predetermined location in the gas supply module; and

[0028] Gas flow upstream of a predetermined location in the gas supply module is controlled to maintain a predetermined gas flow rate in the gas seal.

[0029] Further embodiments, features, and advantages of the present invention, as well as the structure and operation, features, and advantages of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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 indicate corresponding parts, and in which:

[0031] Figure 1 A schematic overview of a lithographic apparatus is depicted;

[0032] Figure 2a 、 Figure 2b 、 Figure 2c as well as Figure 2d Two different versions of a fluid handling system are each depicted in cross-section, with the left-hand and right-hand sides of each version showing different features, which may extend around the entire circumference;

[0033] Figure 3 An immersion system for a photolithography apparatus is depicted in cross section;

[0034] Figure 4a and Figure 4b A humidification device is schematically depicted;

[0035] Figure 5 is a schematic diagram of a gas supply module according to an embodiment of the present invention.

[0036] Figure 6 is a graph of pressure and flow in a gas supply module according to an embodiment of the present invention.

[0037] The features shown in the figures are not necessarily drawn to scale, and the sizes and / or arrangements shown are not limiting. It should be understood that the drawings include optional features that may not be required for the present invention. In addition, not all features of the device are depicted in every drawing, and the drawings may only show some components relevant to describing a particular feature. DETAILED DESCRIPTION

[0038] In this document, the terms "radiation" and "beam" are used to cover all types of electromagnetic radiation, including ultraviolet radiation (eg, having a wavelength of 365, 248, 193, 157 or 126 nm).

[0039] As used herein, the terms "reticle," "mask," or "patterning device" may 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 the pattern to be created in a target portion of the substrate. The term "light valve" may also be used in this context. In addition to classical masks (transmissive or reflective, binary, phase-shift, hybrid, etc.), examples of other such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0040] Figure 1 A lithographic apparatus is schematically shown. The lithographic apparatus comprises an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam B (e.g., UV radiation or DUV radiation); a mask support (e.g., a mask stage) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to precisely position the patterning device MA according to certain parameters; a substrate support (e.g., a substrate stage) WT constructed to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioner PW configured to precisely position the substrate support WT according to certain parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., comprising one or more chips) of the substrate W. A controller 500 controls the overall operation of the apparatus. The controller 500 may be a centralized control system or a system of multiple separate sub-controllers within the various subsystems of the lithographic apparatus.

[0041] In operation, the illumination system IL receives a radiation beam B from a radiation source SO, for example, via a beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for directing, shaping, and / or controlling the radiation. The illuminator IL may be used to condition the radiation beam B so that it has a desired spatial and angular intensity distribution in its cross-section at the plane of the patterning device MA.

[0042] The term "projection system" PS as used herein should be understood broadly as covering various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optical systems, or any combination thereof, as applicable to the exposure radiation used, and / or other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" PS.

[0043] The lithographic apparatus is of a type in which at least a portion of the substrate W may be covered by an immersion liquid having a relatively high refractive index (e.g. water) so as to fill an immersion space 11 between the projection system PS and the substrate W - this is also known as immersion lithography. More information on immersion technology is given in US 6,952,253, which is incorporated herein by reference.

[0044] The lithographic apparatus may be of a type having two or more substrate supports WT (also known as a "dual stage"). In such a "multi-stage" machine, the substrate supports WT may be used in parallel, and / or preparatory steps for subsequent exposure of the substrate W may be performed on a substrate W on one of the substrate supports WT while another substrate W on another substrate support WT is being used to expose a pattern on another substrate W.

[0045] In addition to the substrate holder WT, the lithographic apparatus may further comprise a measurement stage (not depicted in the figures). The measurement stage is arranged to accommodate sensors and / or cleaning equipment. The sensors may be arranged to measure properties of the projection system PS or properties of the radiation beam B. The measurement stage may hold a plurality of sensors. The cleaning equipment may be arranged to clean parts of the lithographic apparatus, for example parts of the projection system PS or parts of the system for providing immersion liquid. When the substrate holder WT is away from the projection system PS, the measurement stage may be moved below the projection system PS.

[0046] In operation, a radiation beam B is incident on a patterning device (e.g. a mask) MA which is held on a mask holder MT and is patterned by a pattern (design layout) present on the patterning device MA. After having passed 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. With the aid of a second positioner PW and a position measurement system IF, the substrate holder WT can be accurately moved, for example, in order to position a different target portion C in the path of the radiation beam B at a focused and aligned position. Similarly, the first positioner PM and possibly another position sensor ( Figure 1 The patterning device MA and the substrate W can be aligned using the mask alignment marks M1, M2 and the substrate alignment marks P1, P2. Although the substrate alignment marks P1, P2 are shown occupying dedicated target portions, they can also be located in the space between target portions. When the substrate alignment marks P1, P2 are located between target portions C, they are referred to as scribe line alignment marks.

[0047] 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. Rotation about the x-axis is called an Rx rotation. Rotation about the y-axis is called an Ry rotation. Rotation about the z-axis is called an Rz rotation. The x-axis and the y-axis define a horizontal plane, while the z-axis is in a 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, so that the z-axis has a component along the horizontal plane.

[0048] Immersion technology has been introduced into lithography systems to improve the resolution of smaller features. In an immersion lithography apparatus, a layer of immersion liquid having a relatively high refractive index is interposed in an immersion space 11 between the apparatus's projection system PS (through which a patterned beam is projected toward the substrate W) and the substrate W. The immersion liquid covers at least the portion of the substrate W below the final element of the projection system PS. Thus, at least the portion of the substrate W that undergoes exposure is immersed in the immersion liquid.

[0049] In commercial immersion lithography, the immersion liquid is water. Typically, the water is high-purity distilled water, such as ultrapure water (UPW), commonly used in semiconductor manufacturing plants. In immersion systems, the UPW is typically purified, and it may undergo additional processing steps before being supplied as the immersion liquid to the immersion space 11. In addition to water, other liquids with a high refractive index can be used as the immersion liquid, for example: hydrocarbons, such as fluorocarbons; and / or aqueous solutions. Furthermore, other fluids besides liquids have also been contemplated for use in immersion lithography.

[0050] In this specification, the description will be made with reference to local immersion, wherein the immersion liquid is confined, when in use, to an immersion space 11 between the final element 100 and a surface facing the final element 100. The facing surface is the surface of the substrate W or a surface of a support table (or substrate holder WT) that is coplanar with the surface of the substrate W. (Note that references to the surface of the substrate W hereinafter also refer in addition to or as an alternative to the surface of the substrate holder WT, unless expressly stated otherwise, and vice versa). A fluid handling structure 12 between the projection system PS and the substrate holder WT is used to confine the immersion liquid to the immersion space 11. The immersion space 11 filled with immersion liquid is smaller in plane than the top surface of the substrate W, and the immersion space 11 remains essentially stationary relative to the projection system PS, while the substrate W and substrate holder WT move beneath it.

[0051] Other immersion systems have been envisioned, such as unconfined immersion systems (so-called "all-wet" immersion systems) and bath immersion systems. In unconfined immersion systems, the immersion liquid covers more than the surface beneath the final element 100. The liquid outside the immersion space 11 is present as a thin film. The liquid may cover the entire surface of the substrate W, or even cover the substrate W and the substrate support WT coplanar with the substrate W. In bath systems, the substrate W is completely immersed in a bath of immersion liquid.

[0052] The fluid handling structure 12 is a structure that supplies immersion liquid to the immersion space 11, removes immersion liquid from the immersion space 11, and thereby confines the immersion liquid to the immersion space 11. It includes features that are part of the fluid supply system. The arrangement disclosed in PCT patent application publication no. WO 99 / 49504 is an early fluid handling structure that includes conduits that supply immersion liquid or recover immersion liquid from the immersion space 11, and whose operation depends on the relative movement of the stage below the projection system PS. In more recent designs, the fluid handling structure extends along at least a portion of the boundary between the final element 100 of the projection system PS and the substrate support WT or substrate W, thereby partially defining the immersion space 11.

[0053] The fluid handling structure 12 can have a selection of different functions. Each function can be derived from corresponding features that enable the fluid handling structure 12 to perform that function. The fluid handling structure 12 can be referred to by a number of different terms, each 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.

[0054] An immersion liquid can be 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, features defined in this paragraph with respect to fluids may be understood to include features defined with respect to liquids.

[0055] The lithographic apparatus has a projection system PS. During exposure of a substrate W, the projection system PS projects a beam of patterned radiation onto the substrate W. 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 located at the end of the beam path, in contact with the immersion liquid. The lens element in contact with the immersion liquid may be referred to as the "last lens element" or "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.

[0056] Figure 2a 、 Figure 2b 、 Figure 2c as well as Figure 2d The different features that may exist in variations of the fluid handling system are shown. Unless otherwise noted, these designs may share similar Figure 2a 、 Figure 2b 、 Figure 2c as well as Figure 2d Some of the same features. The features described herein may be selected individually or in combination as shown or as desired. The figures depict different versions of the fluid handling system, with different features shown on the left and right hand sides, which may extend around the entire circumference. Thus, for example, the fluid handling system may have the same features extending around the entire circumference. For example, the fluid handling system may have only Figure 2a The left-hand side features, or Figure 2a The right-hand side features, or Figure 2b The left-hand side features, or Figure 2b The right-hand side features, or Figure 2c The left-hand side features, or Figure 2c The right-hand side features, or Figure 2d The left-hand side features, or Figure 2dAlternatively, the fluid handling system may be provided with any combination of features from these figures at different locations around the circumference. The fluid handling system may include a fluid handling structure 12 as described in the following variations.

[0057] Figure 2a A fluid handling structure 12 is shown surrounding the bottom surface of the final element 100. The final element 100 has an inverted frustoconical shape. The frustoconical shape has a flat bottom surface and a conical surface. The frustoconical shape protrudes from the flat surface and has a bottom flat surface. The bottom flat surface is an optically active portion of the bottom surface of the final element 100 through which the radiation beam B can pass. The final element 100 may have a coating 30. The fluid handling structure 12 surrounds at least part of the 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 may have complementary shapes. The top surface of the fluid handling structure 12 may be substantially flat. The fluid handling structure 12 may be mounted around the frustoconical shape of the final element 100. The bottom surface of the fluid handling structure 12 may be substantially flat and, when in use, may be parallel to a facing surface of the substrate holder WT and / or substrate W. Therefore, the bottom surface of the fluid handling structure 12 may be referred to as a surface facing the surface of the substrate W. The distance between the bottom surface and the facing surface may be in the range of 20 to 500 microns, desirably in the range of 70 to 200 microns.

[0058] The fluid handling structure 12 extends closer to the facing surfaces of the substrate W and substrate support WT than the final element 100. Thus, an 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 part of the buffer space between the complementary surfaces of the final element 100 and the fluid handling structure 12, for example, at least part of the space between the complementary inner surfaces and the conical surface.

[0059] Immersion liquid is supplied to the immersion space 11 through openings formed in the surface of the fluid handling structure 12. The immersion liquid may be supplied through supply openings 20 in the inner surface of the fluid handling structure 12. Alternatively or in addition, the immersion liquid is supplied from an under supply opening 23 formed in the bottom surface of the fluid handling structure 12. The under supply opening 23 may surround the path of the radiation beam B, and it may be formed by a series of array openings or a single slit. Immersion liquid is supplied to fill the immersion space 11 so that the flow through the immersion space 11 below the projection system PS is laminar. Supplying immersion liquid from the under supply opening 23 also prevents bubbles from entering the immersion space 11. This supply of immersion liquid may act as a liquid seal.

[0060] The immersion liquid can be recovered from a recovery opening 21 formed in the inner surface. The recovery of the immersion liquid through the recovery opening 21 can be by applying a negative pressure; the recovery through the recovery opening 21 is a result of the speed of the immersion liquid flow through the immersion space 11; or the recovery can be the result of both. When viewed in plan, the recovery opening 21 can be located on the opposite side of the supply opening 20. In addition or alternatively, the immersion liquid can be recovered by an overflow recovery 24 located on the top surface of the fluid handling 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 opposite). This allows the direction of the flow to change depending on the relative movement of the fluid handling structure 12 and the substrate W.

[0061] Additionally or alternatively, the immersion liquid may be recovered from beneath the fluid handling structure 12 through a recovery opening 25 formed in the bottom surface of the fluid handling structure 12. The recovery opening 25 may be used to maintain a meniscus 33 of the immersion liquid to the fluid handling structure 12. The meniscus 33 is formed between the fluid handling structure 12 and the facing surface, and it acts as a boundary between the liquid space and the gaseous external environment. The recovery opening 25 may be a porous plate that may recover the immersion liquid in the form of a substantially single-phase flow. The recovery openings in the bottom surface may be a series of pinned openings 32 through which the immersion liquid is recovered. The pinned openings 32 may recover the immersion liquid in the form of a two-phase flow.

[0062] Optionally, radially outwardly relative to the inner surface of the fluid handling structure 12 is an air knife opening 26. Gas can be supplied through the air knife opening 26 at an increased velocity to assist in liquid confinement of the immersion liquid in the immersion space 11. The supplied gas may be humidified and may consist essentially of carbon dioxide. Radially outwardly of the air knife opening 26 is a gas recovery opening 28 for recovering gas supplied through the air knife opening 26.

[0063] Further openings, for example openings to atmosphere, a gas source or a vacuum may be present in the bottom surface of the fluid handling structure 12, i.e. in the surface of the fluid handling structure 12 facing the substrate W. Examples of such optional further openings 50 are shown in FIG. Figure 2a , is shown in dashed lines on the right-hand side of . As shown, the additional opening 50 can be a supply member or an extraction member, which is indicated by a double-headed arrow. For example, if configured to supply, the additional opening 50 can be connected to a liquid supply or a gas supply like any supply member. Alternatively, if configured to extract, the additional opening 50 can be used to extract fluid and can, for example, be connected to the atmosphere, an air source or a vacuum. For example, at least one additional opening 50 can be present between the air knife opening 26 and the gas recovery opening 28, and / or between the pinning opening 32 and the air knife opening 26.

[0064] Figure 2a The two different versions of the fluid handling structure 12 on the left and right sides of the pinned liquid surface 33. Due to the fixed position of the pinned opening 32, Figure 2a The version of the fluid handling structure 12 on the right-hand side of may pin the meniscus 33 in a substantially fixed position relative to the final element 100 . Figure 2a Versions of the fluid handling structure 12 on the left hand side may pin the meniscus 33 below the recovery opening 25 so that the meniscus 33 can move along the length and / or width of the recovery opening 25. In order to direct the radiation beam B to the entire side of the substrate W under exposure, the substrate holder WT supporting the substrate W is moved relative to the projection system PS. In order to maximize the output of substrate W exposed by the lithographic apparatus, the substrate holder WT (and therefore the substrate W) is moved as fast as possible. However, there is a critical relative speed (commonly referred to as the critical scanning speed) above which the meniscus 33 between the fluid handling structure 12 and the substrate W becomes unstable. An unstable meniscus 33 carries a greater risk of losing immersion liquid, for example in the form of one or more droplets. In addition, an unstable meniscus 33 carries a greater risk of causing bubbles to be included in the immersion liquid, particularly when the confined immersion liquid passes the edge of the substrate W.

[0065] Droplets present on the surface of the substrate W can impose thermal loads and be a source of defects. Droplets can evaporate, leaving behind dried stains; they can migrate, transporting contaminants such as particles; they can collide with a larger body of immersion liquid, introducing bubbles into the larger body; and they can evaporate, imposing thermal loads on the surface on which they are located. If this surface is associated with the positioning of a component of the lithographic apparatus relative to the substrate W being imaged, such thermal loads can be a cause of deformation and / or a source of positioning errors. Therefore, the formation of droplets on the surface is undesirable. To avoid the formation of such droplets, the speed of the substrate support WT is therefore limited to a critical scanning speed at which the meniscus 33 remains stable. This limits the throughput of the lithographic apparatus.

[0066] Figure 2a The left hand side of the fluid handling system in may include a spring 60. The spring 60 may be an adjustable passive spring that is 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 an adjustable passive spring is described in US 7,199,874, which is incorporated herein by reference in its entirety. Other biasing devices may also be suitable, such as biasing devices using electromagnetic forces. Although the spring 60 is shown Figure 2a on the left hand side, but it is optional and does not have to be included Figure 2a The spring 60 is not shown in any of the other figures, but may also be included in connection with the Figure 2a 、 Figure 2b 、 Figure 2c or Figure 2d In other variations of the described fluid handling systems.

[0067] Figure 2b Two different versions of the fluid handling structure 12 are shown, one on the left side and one on the right side, which allow for movement of the meniscus 33 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 lead to improved stability and a reduced risk of rupture of the meniscus 33. The speed of the substrate W at the time of rupture of the meniscus 33 is increased, thereby allowing for faster movement of the substrate W under the projection system PS. Consequently, throughput is increased.

[0068] Figure 2b As shown in Figure 2a Like features share like reference numerals.The fluid handling structure 12 has an inner surface that is complementary to the conical surface of the frustoconical shape.The bottom surface of the fluid handling structure 12 is closer to the facing surface than the bottom flat surface of the frustoconical shape.

[0069] Immersion liquid is supplied to the immersion space 11 through supply openings 34 formed in the inner surface of the fluid handling structure 12. The supply openings 34 are located towards the bottom of the inner surface, possibly below the bottom surface of the frusto-conical shape. The supply openings 34 are located around the inner surface, spaced around the path of the radiation beam B.

[0070] The immersion liquid is recovered from the immersion space 11 through the recovery opening 25 in the bottom surface of the fluid handling structure 12. When the facing surface moves below 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 formed by 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 it is separated into liquid and gas. The liquid and gas are recovered through separate channels 36 and 38 from the chamber 35.

[0071] An inner periphery 39 of the bottom surface of the fluid handling structure 12 extends into the immersion space 11, away from the inner surface to form a plate 40. The inner periphery 39 forms a small aperture that can be sized to match the shape and size of the radiation beam B. The plate 40 can serve to isolate immersion liquid from either side thereof. The supplied immersion liquid flows inwardly toward the aperture, through the inner aperture, and then radially outwardly beneath the plate 40 toward the surrounding recovery openings 25.

[0072] The fluid handling structure 12 can be divided into two parts, such as Figure 2b : shown on the right-hand side of the figure: an inner part 12a and an outer part 12b. The inner part 12a and the outer part 12b can move relative to each other, primarily in planes parallel to the facing surfaces. The inner part 12a can have a supply opening 34 and an overflow recovery 24. The outer part 12b can have a plate 40 and a recovery opening 25. The inner part 12a can have an intermediate recovery 42 for recovering immersion liquid flowing between the inner part 12a and the outer part 12b.

[0073] Figure 2b The two different versions of the fluid handling structure in thus allow movement of the meniscus 33 in the same direction as the substrate W, thereby achieving faster scanning speeds and increased throughput of the lithographic apparatus. Figure 2b The migration speed of the meniscus 33 in the fluid handling structure 12 on the left side on the surface of the recovery opening 25 may be slower. Figure 2b The fluid handling structure 12 on the right side allows for faster movement of the meniscus 33 by moving the outer part 12b relative to the inner part 12a and the final element 100. However, it may be difficult to control the intermediate recovery 42 to ensure that sufficient immersion liquid is provided between the inner part 12a and the outer part 12b to prevent contact between them.

[0074] Figure 2c Two different versions of the fluid handling structure 12 are shown on its left side and on its right side, which can be used to pin the meniscus 33 of the immersion liquid to the fluid handling structure 12, as described above with respect to FIG. Figure 2a and / or Figure 2b described. Figure 2c As shown in Figure 2a and / or Figure 2b Common features share the same reference numerals.

[0075] The fluid handling structure 12 has an inner surface that is complementary to the conical surface of the truncated cone shape. The bottom surface of the fluid handling structure 12 is closer to the facing surface than the bottom flat surface of the truncated cone shape. The immersion liquid is delivered 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 34 in the inner surface of the fluid structure 12. Alternatively or additionally, the immersion liquid can be supplied through the supply opening 20 in the inner surface of the fluid structure 12. Alternatively or additionally, the immersion liquid can be supplied through the bottom supply opening 23. The immersion liquid can be recovered via an extraction structure, for example, via a recovery opening 21 formed in the inner surface and / or an overflow recovery 24 and / or one or more openings in the surface of the fluid handling structure 12 as described below.

[0076] Figure 2c Two different versions of the left and right side fluid handling structures 12 pin the meniscus 33 . Figure 2c The version of the fluid handling structure 12 on the right may pin the meniscus 33 at a substantially fixed position relative to the final element 100 due to the fixed position of the recovery opening 32a. Figure 2c The left-hand version of the fluid handling structure 12 may pin the meniscus 33 below the recovery opening 25 so that the meniscus 33 can move along the length and / or width of the recovery opening 25 .

[0077] As mentioned above about Figure 2b As depicted, the inner periphery of the bottom surface of the fluid handling structure 12 may extend into the immersion space 11, away from the inner surface, to form a plate 40, as shown on the left hand side. As described above, this may form a small aperture and may isolate the immersion liquid on either side and / or cause the immersion liquid to flow inwardly towards the aperture, through the inner hole, and then radially outwardly beneath the plate 40 towards the surrounding recovery openings 25. Although this feature is not Figure 2c , but may optionally be combined with the other features shown. Preferably, as shown on the left hand side, immersion liquid is supplied to the immersion space 11 through supply openings 34 formed in the inner surface of the fluid handling structure 12. The supply openings 34 are located towards the bottom of the inner surface, possibly below the bottom surface of the frusto-conical shape. The supply openings 34 are located around the inner surface and are spaced around the path of the radiation beam B. Alternatively or in addition, immersion liquid may be supplied through supply openings 20 in the inner surface of the fluid structure 12. Alternatively or in addition, immersion liquid is supplied through lower supply openings 23. Although supply openings 34 are the preferred liquid supply, any combination of supply openings 34, supply openings 20 and / or lower supply openings 23 may be provided.

[0078] like Figure 2cAs shown on the left hand side of FIG, the fluid handling system may include a fluid handling structure 12 as described above and additional equipment 3000. The fluid handling structure 12 may have an extraction member (such as a recovery opening 25) and a liquid supply opening (such as a lower supply opening 23). It should be understood that the fluid handling structure 12 may include, in combination with the additional equipment 3000, as described above. Figure 2a The left hand side, Figure 2a On the right side, Figure 2b The left hand side, Figure 2b the right-hand side or (as described below) Figure 2c The right-hand side exposes any configuration.

[0079] The further device 3000 may be further referred to as a droplet catcher. The further 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 across the surface of the substrate W. The further device 3000 may include a liquid supply member 3010 and at least one extraction member 3020. The at least one extraction member 3020 may be formed to surround the at least one supply member 3010 in a plane. The at least one liquid supply member 3010 may be configured to provide further liquid to a space 3110 between at least a portion of the further device 3000 and the surface of the substrate W. The further device 3000 may be configured to recover at least some of the liquid via the at least one extraction member 3020. The further device 3000 may be used to combine any liquid remaining on the surface of the substrate W with the liquid in the space 3110 and then extract the liquid using the further device 3000, so that the amount of liquid remaining on the surface of the substrate W is reduced.

[0080] exist Figure 2c , the further device 3000 is shown as a separate device from the fluid handling structure 12. The further device 3000 may be positioned adjacent to the fluid handling structure 12. Alternatively, the further device 3000 may be part of the fluid handling structure 12, i.e. integral therewith (however, as in Figure 3 d, either arrangement can be chosen).

[0081] The further apparatus 3000 may be configured to provide a liquid to the space 3110 that is separate from the liquid provided by the fluid handling structure 12 .

[0082] Additionally or alternatively, the fluid handling structure 12 may have a Figure 2c. 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 24a and 24b) formed on the surface of the fluid handling structure 12. The gas supply opening 24a can be omitted, i.e., 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 may be the same as the lower supply opening 23 in the bottom surface of the fluid handling structure 12 described above. Figure 2b 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-hand side of FIG. 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 (i.e., the bottom surface of the fluid handling structure 12).

[0083] 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., recovery opening 32a) through which the fluid handling structure 12 extracts fluid from beneath the fluid handling structure 12 and may recover immersion liquid in a single-phase flow. The other of the two extraction members, e.g., recovery opening 32b, may function as a two-phase extractor to recover immersion liquid. The porous material 37 need not be flush with the bottom surface of the fluid handling structure 12.

[0084] Specifically, the fluid handling structure 12 may include a liquid supply member (e.g., the lower supply opening 23), a first extraction member (e.g., the recovery opening 32a) located radially outside the liquid supply member, and a first gas supply member (e.g., the gas supply opening 24a) located radially outside the first extraction member, and a second extraction member (e.g., the recovery opening 32b) located radially outside the first gas supply member, and a second gas supply member (e.g., the gas supply opening 24b) located radially outside the second extraction member. Figure 2a Similarly, additional openings (eg, openings to atmosphere or a gas source or vacuum) may be present in the bottom surface of the fluid handling structure 12, as previously described (with respect to the fluid handling structure 12).

[0085] For example, at least one additional opening (not shown) can be provided in the bottom surface of the fluid handling structure 12. This additional opening is optional. This additional opening can be arranged between the first extraction member (e.g., recovery opening 32a) and the first gas supply member (e.g., gas supply opening 24a), as described in the above arrangement. Alternatively or in addition, this additional opening can be arranged between the second extraction member (e.g., recovery opening 32b) and the second gas supply member (e.g., gas supply opening 24b), as described in the above arrangement. This additional opening can be identical to the additional opening 50 described above.

[0086] Optionally, the fluid handling structure 12 includes a recess 29. The recess 29 can be provided between the recovery opening 32a and the recovery opening 32b, or between the gas supply opening 24a and the recovery opening 32b. The shape of the recess 29 can be uniform around the fluid handling structure 12 and can 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 24b can be provided on an inclined surface, such as Figure 2c As shown. In the case where the groove 29 is provided between the supply opening 24a and the recovery opening 32b, the gas supply opening 24b may be provided on an inclined surface or on a portion of the bottom surface of the fluid handling structure 12 that is parallel to the surface of the substrate W. Alternatively, the shape of the groove 29 may vary around the circumference of the fluid handling structure 12. The shape of the groove 29 may be changed to modify the effect of the gas supplied from the gas supply member on the fluid below the fluid handling structure 12.

[0087] Figure 2d Two different versions of the fluid handling structure 12 are shown in the left and right halves. Figure 2d The left half of the fluid handling structure 12 has a liquid injection buffer 41a and a liquid injection hole 41. The liquid injection buffer 41a holds a buffered amount of immersion liquid, and the liquid injection hole 41 supplies the immersion liquid from the liquid injection buffer to the space 11. The outer side of the liquid injection hole 41 is an internal liquid recovery hole 43 for guiding the liquid to the internal recovery buffer 43a provided with a porous member. Figure 2c A groove 29, similar to the groove described above, is provided outside the internal liquid recovery hole 43. Outside of groove 29, below the fluid handling structure 12, is a gas guide groove 44, within which an external recovery hole 44a is formed. External recovery hole 44a directs the two-phase recovery flow to an external recovery buffer 44b, also provided with a porous member. At the outermost side is a gas seal hole 45, which communicates with the space below the fluid handling structure 12 at a gas seal buffer volume 45a to provide gas flow to accommodate the immersion liquid.

[0088] Figure 2d The fluid handling structure 12 in the right half of the figure has a liquid supply opening 20 in its inner bevel. In the bottom surface of the fluid handling structure 12 (from the inside to the outside) there is an extraction opening 25 provided with a porous member 37; a first gas knife opening 26a; a second gas knife opening 26b; and a third gas knife opening 26c. Each of these openings opens into a groove in the bottom surface of the fluid handling structure 12 that provides a buffer volume. The outermost portion of the fluid handling structure 12 is stepped to provide greater separation between the fluid handling structure 12 and the substrate W.

[0089] Figures 2a to 2d Shown are examples of different configurations that can be used as parts of a fluid handling system. It should be understood that the examples provided above refer to specific extraction members and recovery members, but it is not necessary to use the exact type of extraction members and / or recovery members. In some cases, different terms are used to indicate the position of the member, but the same functional characteristics can be provided. The example of the above-mentioned extraction member includes recovery opening 21, overflow recovery 24, recovery opening 25 (possibly including porous plate and / or chamber 35), gas recovery opening 28, pinning opening 32, recovery opening 32a, recovery opening 32b and / or intermediate recovery 42. The example of the above-mentioned supply member includes supply opening 20, lower supply opening 23, air knife opening 26, gas supply opening 24a, gas supply opening 24b and / or supply opening 34. Typically, the extraction member for extracting / recovering fluid, liquid or gas can be interchanged with at least any one of the other examples for extracting / recovering fluid, liquid or gas respectively. Similarly, the supply member for supplying fluid, liquid or gas can be interchanged with at least any one of the other examples for supplying fluid, liquid or gas respectively. The extraction member may extract / recover fluid, liquid or gas from the space by being connected to a negative pressure that draws the fluid, liquid or gas into the extraction member.The supply member may supply fluid, liquid or gas to the space by being connected to a relevant supply.

[0090] As previously mentioned, while the use of immersion liquids is advantageous for improving the resolution of smaller features on the substrate W, the use of immersion liquids also presents challenges associated with the introduction of defects on the substrate W.

[0091] Typically, when an immersion liquid is used, droplets of the immersion liquid may remain on the surface of the substrate W. The meniscus 33 at the edge of the immersion liquid may collide with any droplets on the surface of the substrate W. When droplets strike the meniscus 33, gas may be entrained in the immersion liquid. This may cause bubbles in the immersion liquid. The formation of bubbles in the immersion liquid can cause defects on the substrate W. Droplets remaining on the surface of the substrate W may cause drying spots and / or affect the chemical properties of the resist, also causing defects.

[0092] Very small bubbles may dissolve in the immersion liquid before they reach the exposure area of ​​the immersion space 11. Bubbles of carbon dioxide typically dissolve faster than bubbles of air. Bubbles of CO2, having a solubility fifty-five (55) times greater than that of bubbles of nitrogen and a diffusivity 0.86 times that of bubbles of nitrogen, will typically dissolve in a time thirty-seven (37) times shorter than for bubbles of nitrogen of the same size. Supplying CO2 adjacent to the meniscus 33 means that bubbles of CO2 will dissolve into the immersion liquid much faster than if other gases with lower diffusivities were used. Therefore, the use of CO2 in the fluid handling structure 12 is known to reduce the number of imaging defects, thereby allowing higher throughput (e.g., higher speed of the substrate W relative to the fluid handling structure 12) and lower defect rates.

[0093] Controlling temperature in a lithographic apparatus is extremely important; it is desirable to maintain the temperature of sensitive apparatus components (e.g., the substrate holder WT and its vicinity) at a very precise target temperature. Therefore, evaporation of the immersion liquid in the two-phase extraction flow is an undesirable heat load. To minimize this heat load, it is desirable to use a humidified gas in the fluid handling structure 12.

[0094] Figure 3 The gas supply arrangement in the fluid handling structure 12 is depicted. The gas supply system includes a gas source 211 to provide gas to at least one gas knife opening 210 and at least one gas supply opening 220. In one embodiment, the same gas source 211 is used to provide gas to at least one gas knife opening 210 and at least one gas supply opening 220, as shown in FIG. Figure 3 The gas supplied to the gas supply opening 220 can be controlled using a valve (not shown) to redirect the gas from the gas knife opening 210 to the gas supply opening 220. In one embodiment, the gas supply system may include a plurality of gas sources to provide gas to at least one gas knife opening 210 and at least one gas supply opening 220, respectively.

[0095] In one embodiment, the gas supply system includes a humidifier 212 to control the humidity of the gas provided by the at least one gas source. In one embodiment, the gas supplied from the gas source 211 is substantially pure CO2 gas, and the output of the gas supply system is humidified CO2 gas. In one embodiment, the humidifier 212 increases the humidity of the CO2 gas provided by the at least one gas source. In one embodiment, the humidifier 212 is connected to the gas source 211, such as Figure 3 Depicted.

[0096] In one embodiment, the fluid handling structure 12 may include a reservoir 213. The reservoir 213 may be between at least one gas supply system and the gas knife opening 210 and the gas supply opening 220. In one embodiment, the reservoir 213 may be a section between the gas supply system and at least one of the gas knife opening 210 and the gas supply opening 220, the section having an increased cross-sectional area. In one embodiment, the fluid handling structure 12 may include a first path 214 from the reservoir 213 to the gas knife opening 210 and a second path 215 from the reservoir 213 to the gas supply opening 220. In one embodiment, the reservoir 213 may not be provided, i.e., the reservoir 213 is not required.

[0097] Providing a reservoir 213 allows for better control of the gas exhausted from the air knife opening 210 and / or the gas supply opening 220. For example, gas can accumulate in the reservoir 213 and can be more evenly distributed from the air knife opening 210 and the gas supply opening 220 along their lengths. Providing a humidifier 212 allows for better control of the gas exhausted from the air knife opening 210 and / or the gas supply opening 220. For example, the humidity of the gas supplied to the air knife opening 210 and / or the gas supply opening 220 can be controlled to affect the humidity of the gas environment adjacent to the meniscus 33.

[0098] In one embodiment, the amount of gas supplied to the gas supply openings 220 and / or the gas knife openings 210 is variable. In one embodiment, the gas supplied to the gas supply openings 220 and / or the gas knife openings 210 is dynamically controlled, i.e., the supplied gas can be controlled and changed during use. For example, the gas discharged from the gas supply openings 220 and / or the gas knife openings 210 can be dynamically controlled depending on certain characteristics of the fluid handling structure 12, including but not limited to the direction of movement, speed, velocity, and / or position of the fluid handling structure 12.

[0099] In one embodiment, the air knife opening 210 includes a series of discrete apertures. For example, the air knife opening 210 can be provided with two discrete apertures, for example, each aperture is on either side of the quadrilateral formed by the air knife opening 210. Alternatively, the air knife opening 210 can have a single discrete aperture along each side of the quadrilateral formed by the air knife opening 210. Thus, the air knife opening 210 can be provided by four discrete apertures. The shape of each aperture is not particularly limited, and the air knife opening 210 can be provided by any number of discrete apertures.

[0100] Each aperture may be individually controlled to vary the gas flow rate and / or gas velocity of gas exhausted from the different apertures of the gas knife openings 210. At least one aperture may be dynamically controlled depending on certain characteristics of the fluid handling structure 12, including, but not limited to, the direction, speed, velocity, and / or position of movement of the fluid handling structure 12. For example, in use, the apertures of the gas knife openings 210 located on the advancing side of the fluid handling structure 12 may be controlled to cause gas to be exhausted at a lower gas flow rate and / or gas velocity, respectively, than the gas exhaust apertures of the gas knife openings 210 located on the retreating side of the fluid handling structure 12.

[0101] Similarly, the gas supply openings 220 may additionally or alternatively include a series of discrete apertures as described herein, which may be individually controlled as described herein.

[0102] Figure 4a and Figure 4b Shows that it can be Figure 3 The humidifying device 150 is used in conjunction with the gas supply system.

[0103] The basic arrangement of the humidifying device 150 is Figure 4a is shown in , and a more complex structure based on the same principle is shown in Figure 4b is shown in Figure 4a In the embodiment of the present invention, humidifying device comprises film 600, and the behavior of this film 600 is as impermeable to the liquid (usually (ultrapure) water) that will humidify gas, but is permeable to the vapor of this liquid. Should be possible to pressurize the liquid side of film (although this is not necessary for hydrophilic membrane as described below), and should not have liquid to pass through film. Also can pressurize the gas side (at least use air or its composition, such as nitrogen, oxygen etc.), and also will not have bubble to pass through film. In some cases, liquid can wet the membrane material, then evaporates. In other cases, film 600 only allows the vapor of liquid to pass through, and liquid molecules can leave film 600 and enter gas. A small amount of gas may dissolve in the liquid from the gas side of film 600, but can not form bubble in liquid. Therefore, film 600 can be regarded as permeable to the vapor of liquid.

[0104] The first conduit 610 directs the gas to be humidified to one side of the membrane 600, and the second conduit 620 directs the liquid used to humidify the gas to the other side of the membrane 600. Since the gas is present on one side of the membrane 600 and the liquid is present on the other side of the membrane 600, the vapor from the liquid will pass through the membrane 600 and humidify the gas. Preferably, the flow of gas is provided through the membrane 600, so that the third conduit 630 is provided for directing the humidified gas away from the membrane 600, and the fourth conduit 640 is provided for directing the liquid away from the other side of the membrane 600.

[0105] A humidifying device similar to this is disclosed in WO 2005 / 010619, and much of what is described therein applies here, particularly regarding the shape of the membrane 600 and how it is connected. However, in contrast to the disclosure of WO 2005 / 010619, the membrane 600 in one embodiment of the present invention can be provided with a lyophilic surface. In other words, the contact angle of the liquid on one side of the membrane 600 with the membrane 600 is less than 90°, preferably less than 70°, more preferably less than 60°, even more preferably less than 50°, and most preferably less than 30° or even less than 20°.

[0106] One suitable type of material for use as membrane 600 is a polymerized fluorinated sulfonic acid copolymer, which is a synthetic ionic polymer. The sulfonic acid groups are chemically active, but they are fixed in the polymer matrix. One such material has the following chemical formula:

[0107]

[0108] The hydrophilic properties of the membrane can be provided, for example, by a coating (on one or both sides of the membrane 600) and / or by applying an electrical potential to the membrane 600. These types of membranes have previously been used in vapor purification systems, such as those sold under the Intaeger trademark by Rasirc of San Diego, California, US.

[0109] The advantage of such membranes is that low-pressure liquids can be used on the liquid side of the membrane, and there is better efficiency in evaporating the liquid on the gas side, i.e., greater mass transfer across the membrane. In addition, for lyophilic membranes, there is no need to pressurize the liquid, resulting in a significantly lower pressure drop (10 times) in the actual hardware compared to lyophobic membranes.

[0110] It is advantageous to maximize the surface area of ​​the membrane 600, and one preferred embodiment is where the membrane 600 is a hollow fiber with the liquid passing through the interior of the hollow fiber and the gas passing over the exterior of the hollow fiber (although vice versa is also possible). One such embodiment is Figure 4b is shown in FIG, where liquid is provided through a hollow fiber 660 comprising a membrane 600. Only one fiber is provided in FIG. Figure 4b , but of course the second conduit 620 can be connected to multiple fibers in parallel.

[0111] exist Figure 4b In the embodiment of FIG. 5 , gas enters the housing 650 surrounding the hollow fibers 660 and passes over the hollow fibers 660 after being guided into the housing by the conduit 610 . Then, once humidified, the gas is guided out of the housing by the third conduit 630 .

[0112] In order to provide a flow of gas and a flow of liquid, a liquid supplier and a gas supplier are required. These can take the form of pumps that provide a source of liquid and compressed gas, for example.

[0113] The gas supply module 400 of the embodiment of the present invention is Figure 5 Schematically depicted in FIG. Gas, such as carbon dioxide, is supplied from a gas source (not shown) to an input control valve 401, which regulates the flow of gas into the gas supply module 400. As will be discussed in further detail, the flow of gas through the gas supply module 400 is regulated based on pressure measurements at predetermined points within the gas supply module 400. The inventors have determined that a reliable relationship between pressure and gas flow can be determined, enabling pressure sensors, which are not susceptible to long-term drift like mass flow controllers or mass flow meters, to be used to monitor and control the flow of gas through the gas supply module 400. Depending on the exact layout of the gas supply module 400, a variety of different locations for the pressure sensor may be suitable. Ideally, the location of the pressure sensor should be selected so that the relationship between pressure and flow is substantially linear, at least over the range of flow rates of interest. Desirably, the pressure sensor is located downstream of any variable elements in the gas supply module 400. Desirably, the pressure sensor is located downstream of the humidifier 150. Desirably, the pressure sensor is located downstream of the temperature regulator 408.

[0114] The relationship between pressure and flow rate can be determined via theoretical calculations or through empirical calibration. In many cases, small variations in manufacturing will affect the relationship between pressure and flow, so that to achieve the desired level of accuracy, it may be desirable to calibrate each gas supply module 400 before installing it in the lithographic apparatus. However, such variations generally remain stable over time, making subsequent recalibration unlikely to be necessary except in the event of major modifications to the lithographic apparatus or replacement of components within the gas supply module 400.

[0115] Reference again Figure 5 Following control valve 401, a safety sensor 402 is provided to monitor the gas pressure in gas supply module 400. There may be two safety sensors 402. Safety sensors 402 can monitor whether the pressure in gas supply module 400 remains within an acceptable range and, in the event of a dangerous deviation, alert the user or shut down the apparatus. A manual shutoff valve 403 is provided to manually shut off the gas supply when necessary. A filter 404 is provided to ensure that no particles or other contaminants enter the lithography apparatus.

[0116] The filtered gas output by the filter 404 passes through the humidifier 150 and the temperature regulator 408 and is then supplied to the fluid handling structure 12, in particular to form the gas knife. It is desirable that the humidifier 150 and the temperature regulator 408 are as close to the fluid handling structure 12 as possible, while the components 401 to 404 can be located elsewhere, even outside the main body of the lithographic apparatus. Therefore, a hose 405 can be used to connect the filter 404 to the humidifier 150. The hose 405 can be relatively long, for example several meters, so that an effective flow resistance can be formed, which is indicated as 406 in the figure. The humidifier 150 and the temperature regulator 408 can be included in a point-of-use module 416, which is physically close to the point where the conditioned gas will be used.

[0117] A pressure sensor 407 (an example of a measurement system) is provided in the outlet of the humidifier 150 and is connected to the control valve 401 in a feedback loop to regulate the flow of gas entering the gas supply module 400 so that a constant pressure corresponding to a desired flow rate is maintained at the output of the humidifier 150. Additional sensors 415 may also be provided at this location, for example, for safety or to provide redundancy. An additional pressure sensor 410 is shown between the output of the temperature regulator 408 and the input to the fluid handling structure 12. This is an alternative location for providing feedback control to the control valve 401 for the pressure sensor.

[0118] Alternatively, the flow of gas through the gas supply module 400 can be regulated by a mass flow controller (another example of a measurement system) within the gas supply module 400. In such an arrangement, the mass flow controller replaces the control valve 401, and the feedback loop from the pressure sensor 407 can be omitted. The mass flow controller can have an internal feedback loop. Typically, a mass flow controller is a mass flow meter (i.e., a sensor) combined with a control valve and feedback electronics between the sensor and the control valve.

[0119] In one embodiment, temperature regulator 408 comprises a heat exchanger that is supplied with a temperature-control fluid via inlet 412. The temperature-control fluid can, for example, come from the same supply used to control the temperature of projection system PS. Since the temperature of the fluid used to humidify the gas is not as critical as other components of the device (e.g., projection system PS), the fluid that has already passed through temperature regulator 408 can conveniently be supplied as input to humidifier 150. The temperature of the fluid used to humidify the gas should be high enough to achieve a sufficient evaporation rate of the fluid in humidifier 150. Outlet 413 returns the fluid for reconditioning.

[0120] The flow restriction 409 causes a sampling point which can be used for testing purposes such as measurement of humidity using external tools. The sampling point is typically covered and the flow restriction 409 is provided to limit gas leakage if the cover is not properly installed.

[0121] As described above, in order to effectively control the gas flow rate based on the measured pressure, it is desirable to accurately understand the relationship between pressure and flow rate. Figure 6 Figure 1 shows pressure and flow measurements made in an experimental setup corresponding to an embodiment of the present invention. The pressure is given in arbitrary units on the x-axis and the flow is given in arbitrary units on the y-axis. Pressure measurements are made using pressure sensors 407 (line A, filled circles) and 415 (line B, filled squares) and are correlated with flow measurements at the output of the gas knife. The pressure sensors 407 and 415 are located between the humidifier and the heat exchanger, but can also be located elsewhere in the gas supply module. It will be seen that the pressure measured by the two sensors has a highly linear relationship with the flow (R 2 = 0.000 and 0.9974), and by averaging the two pressure readings (line C, open circles), an even more linear measurement (R 2 =0.9992) can be obtained.

[0122] The gas supply module 400 described above can also be used in a further device 3000 that functions as a droplet removal system (or droplet catcher), as described above in Figure 2c As described in .

[0123] The present invention may provide a lithographic apparatus. The lithographic apparatus may have any / all other features or components of the lithographic apparatus described above. For example, the lithographic apparatus may optionally include at least one or more of a source SO, an illumination system IL, a projection system PS, a substrate support WT, etc.

[0124] In particular, the lithographic apparatus may comprise a projection system PS configured to project a radiation beam B onto an area of ​​a surface of a substrate W. The lithographic apparatus may further comprise a projection system PS configured to project a radiation beam B onto a surface of a substrate W. Figures 2a to 2d The fluid handling system described in any one of the above embodiments and variations.

[0125] The lithographic apparatus may include an actuator (not shown) configured to move a substrate W relative to a fluid handling system. Thus, the actuator may be used to control the position of the substrate W (or alternatively, the position of the fluid handling system). The actuator may be or may include a substrate holder (e.g., substrate table) WT and / or a substrate holder configured to hold the substrate W and / or a second positioner PW configured to precisely position the substrate holder WT.

[0126] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of integrated circuits, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

[0127] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented 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.), and the like. In addition, 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 that such actions are actually caused by a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., and in doing so may cause actuators or other devices to interact with the physical world.

[0128] Although embodiments of the present invention may be specifically referenced herein in the context of a lithographic apparatus, embodiments of the present invention may also be used in other apparatuses. Embodiments of the present invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or a mask (or other patterning device). These apparatuses may generally be referred to as lithographic tools. Such lithographic tools may use ambient (non-vacuum) conditions.

[0129] Although the above may have specifically referenced the use of embodiments of the present invention in the context of optical lithography, it will be appreciated that the present invention is not limited to optical lithography where the context permits.

[0130] The examples include the following numbered clauses:

[0131] 1. A gas supply module for a fluid handling system in a lithography apparatus, the gas supply system comprising:

[0132] a humidifier having a humidifier input and a humidifier output;

[0133] a first conduit configured to direct gas to the humidifier input;

[0134] a second conduit configured to supply humidified gas to the fluid handling system;

[0135] a control valve configured to control a flow of gas in one of the first conduit and the second conduit;

[0136] a measurement system configured to measure the pressure downstream of the control valve and generate a control signal;

[0137] wherein the control valve maintains a constant pressure in the one of the first conduit and the second conduit in response to the control signal.

[0138] 2. The gas supply module according to clause 1, wherein the control valve is provided in the first conduit.

[0139] 3. The gas supply module according to clause 1, wherein the control valve is provided in the second conduit.

[0140] 4. A gas supply module according to clause 1 or 2, wherein the measurement system comprises a pressure sensor configured to measure the pressure in the first conduit.

[0141] 5. A gas supply module according to clause 1, 2 or 3, wherein the measurement system comprises a pressure sensor configured to measure the pressure in the second conduit.

[0142] 6. The gas supply module according to any of the preceding clauses, further comprising a heat exchanger downstream of the humidifier, the heat exchanger being configured to adjust the temperature of the humidified gas.

[0143] 7. The gas supply module according to clause 6, further comprising a liquid supply system configured to supply liquid to the humidifier and the heat exchanger.

[0144] 8. A gas supply module according to any of the preceding clauses, wherein the control valve is configured to maintain the pressure in the one of the first and second conduits so that the gas flow rate in the second conduit is a predetermined rate, which is greater than 50nlpm, desirably greater than 75nlpm.

[0145] 9. A fluid handling system for a lithographic apparatus, the fluid handling system comprising a gas supply module according to any of the preceding clauses; wherein the gas supply module is configured to supply gas to a gas seal, the gas seal being configured to confine the fluid to a region.

[0146] 10. A lithographic apparatus comprising the fluid handling system according to clause 9.

[0147] 11. A method for manufacturing a device, comprising:

[0148] confining the liquid to a space between the projection system and the substrate using a gas seal, the gas seal being supplied with gas from a gas supply module;

[0149] projecting a patterned beam of radiation through the liquid onto the substrate using the projection system;

[0150] measuring the pressure at a predetermined location in the gas supply module; and

[0151] Gas flow upstream of the predetermined location in the gas supply module is controlled to maintain a predetermined gas flow rate in the gas seal.

[0152] 12. A method of calibrating a gas supply module of a fluid handling system for a lithographic apparatus, the method comprising:

[0153] measuring a pressure at a predetermined location in the gas supply module;

[0154] measuring a gas flow rate output by the gas supply module; and

[0155] A target pressure at the predetermined location is determined to provide a desired gas flow rate.

[0156] 13. The method of clause 12, wherein the calibration is performed while the gas supply module is fluidly connected to the fluid handling system.

[0157] 14. A gas supply module for a fluid handling system in a lithographic apparatus, the gas supply system comprising:

[0158] a humidifier having a humidifier input and a humidifier output;

[0159] a first conduit configured to direct gas to the humidifier input;

[0160] a second conduit configured to supply humidified gas to the fluid handling system;

[0161] a control valve configured to control a flow of gas in one of the first conduit and the second conduit;

[0162] A feedback system is connected to a sensor downstream of the control valve and is configured to maintain a constant flow in the second conduit.

[0163] Although specific embodiments of the present invention have been described above, it should be understood that the present invention may be practiced in ways other than those described. The above description is intended to be illustrative and not limiting. Therefore, it should be understood by those skilled in the art that modifications may be made to the described invention without departing from the scope of the appended claims.

Claims

1. A gas supply module for a fluid handling system in a lithography apparatus, the gas supply system comprising: a humidifier having a humidifier input and a humidifier output; a first conduit configured to direct gas to the humidifier input; a second conduit configured to supply humidified gas to the fluid handling system; a control valve configured to control a flow of gas in one of the first conduit and the second conduit; a measurement system configured to measure the pressure downstream of the control valve and generate a control signal; wherein the control valve maintains a constant pressure in the one of the first conduit and the second conduit in response to the control signal. 2 . The gas supply module according to claim 1 , wherein the control valve is provided in the first conduit. The gas supply module according to claim 1 , wherein the control valve is provided in the second conduit. 4 . The gas supply module according to claim 1 , wherein the measurement system comprises a pressure sensor configured to measure the pressure in the first conduit.

5. A gas supply module according to claim 1, 2 or 3, wherein the measurement system comprises a pressure sensor configured to measure the pressure in the second conduit.

6. The gas supply module according to any one of the preceding claims, further comprising a heat exchanger downstream of the humidifier, the heat exchanger being configured to adjust the temperature of the humidified gas. 7 . The gas supply module according to claim 6 , further comprising a liquid supply system configured to supply liquid to the humidifier and the heat exchanger.

8. A gas supply module according to any one of the preceding claims, wherein the control valve is configured to maintain the pressure in the one of the first and second conduits so that the gas flow rate in the second conduit is a predetermined rate, the predetermined rate being greater than 50 nlpm, desirably greater than 75 nlpm.

9. A fluid handling system for a lithographic apparatus, the fluid handling system comprising a gas supply module according to any one of the preceding claims; wherein the gas supply module is configured to supply gas to a gas seal, the gas seal being configured to confine the fluid to a region.

10. A lithographic apparatus comprising the fluid handling system according to claim 9.

11. A method for manufacturing a device, comprising: confining the liquid to a space between the projection system and the substrate using a gas seal, the gas seal being supplied with gas from a gas supply module; projecting a patterned beam of radiation through the liquid onto the substrate using the projection system; measuring a pressure at a predetermined location in the gas supply module; as well as Gas flow upstream of the predetermined location in the gas supply module is controlled to maintain a predetermined gas flow rate in the gas seal.

12. A method of calibrating a gas supply module of a fluid handling system for a lithographic apparatus, the method comprising: measuring a pressure at a predetermined location in the gas supply module; measuring a gas flow rate output by the gas supply module; as well as A target pressure at the predetermined location is determined to provide a desired gas flow rate.

13. The method of claim 12, wherein the calibration is performed while the gas supply module is fluidly connected to the fluid handling system.

14. A gas supply module for a fluid handling system in a lithographic apparatus, the gas supply system comprising: a humidifier having a humidifier input and a humidifier output; a first conduit configured to direct gas to the humidifier input; a second conduit configured to supply humidified gas to the fluid handling system; a control valve configured to control a flow of gas in one of the first conduit and the second conduit; A feedback system is connected to a sensor downstream of the control valve and is configured to maintain a constant flow in the second conduit.

Images