Fluid processing system, method and lithographic apparatus

Abstract

A fluid treatment system includes: a liquid confinement structure configured to confine an immersion liquid to a space between at least a portion of the liquid confinement structure and a surface of a substrate, the liquid confinement structure having an aperture forming a passage therein for passage of a radiation beam to irradiate the surface of the substrate by passing through the immersion liquid; and a diagnostic tool configured to detect an abnormal condition in the fluid treatment system, the diagnostic tool comprising an acoustic system configured to measure acoustic characteristics of the liquid confinement structure and / or the immersion liquid, where the acoustic system comprises a transducer configured to emit an acoustic detection signal to and / or receive acoustic waves from the immersion liquid.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to EP application 22211041.3, filed on December 2, 2022, which is incorporated herein by reference in its entirety. Technical field

[0003] The present invention relates to a fluid handling system and a device manufacturing method. The present invention also relates to a lithographic apparatus comprising a fluid handling system. Background art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern onto a substrate. For example, a lithographic apparatus can be used to manufacture integrated circuits (ICs). For example, a lithographic apparatus projects 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 to the target portion at once; 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 parallel or anti-parallel to this direction.

[0005] With the continuous progress of the semiconductor manufacturing process, the dimensions of circuit elements have been continuously decreasing, and the number of functional elements (such as transistors) per device has been steadily increasing for decades, following a trend commonly known as "Moore's Law". To keep up with Moore's Law, the semiconductor industry has been pursuing technologies capable of creating 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. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm.

[0006] Further improvement in the resolution of smaller features can be achieved by providing an immersion fluid having 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 because the exposure radiation will have a shorter wavelength in the fluid compared to in a gas. The effect of the immersion fluid can also be regarded 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 structure to a local area between the projection system of the lithographic apparatus and the substrate.

[0008] In a lithographic apparatus using an immersion liquid (commonly referred to as an immersion lithographic apparatus), imaging errors may occur if bubbles (such as air) enter the immersion liquid and the beam path. Bubbles in the beam path may distort the image projected onto the substrate. Since the substrate usually moves relative to the projection lens faster than any bubble, the presence of floating bubbles in the immersion liquid may cause characteristic stripes on the exposed substrate. Bubbles fixed to the substrate may cause recognizable circular imaging defects. However, when such defects are observed, many substrates may already have been exposed with imaging errors, thus reducing the yield. Summary of the Invention

[0009] An object of the present invention is to provide a fluid handling system and method in which abnormal conditions, such as the presence of bubbles or contaminants in the fluid handling system, can be detected quickly.

[0010] According to a first aspect of the present invention, there is provided a fluid handling system, comprising:

[0011] A liquid confinement structure configured to confine an immersion liquid to a space between at least a part of the liquid confinement structure and the surface of a substrate, the liquid confinement structure having a hole formed therein for a radiation beam to pass through to irradiate the surface of the substrate by passing through the immersion liquid; and

[0012] A diagnostic tool configured to detect a condition in the fluid handling system, the diagnostic tool including an acoustic system configured to measure an acoustic characteristic of the liquid confinement structure and / or the immersion liquid,

[0013] wherein the acoustic system includes a transducer configured to emit acoustic waves into the immersion liquid and / or receive acoustic waves from the immersion liquid.

[0014] According to a second aspect of the present invention, there is provided a lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held by the substrate holder, and the above-mentioned fluid handling system.

[0015] According to a third aspect of the present invention, there is provided a device manufacturing method in a lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held by the substrate holder, and a fluid handling system, the method comprising:

[0016] Using the fluid handling system to confine an immersion fluid to a space between at least a part of the fluid handling system and the surface of the substrate;

[0017] Emitting an acoustic detection signal into the immersion liquid;

[0018] Receiving a return signal in response to the detection signal;

[0019] Detecting a condition in a fluid handling system based on a return signal; and

[0020] Projecting a patterned radiation beam onto a substrate through an immersion fluid in space.

[0021] According to a fourth aspect of the present invention, there is provided a droplet removal system comprising:

[0022] A liquid supply member configured to supply liquid to a space between at least a part of the droplet removal system and the surface of a substrate;

[0023] A pumping member configured to pump liquid from the space;

[0024] A diagnostic tool configured to detect a condition in the droplet removal system, the diagnostic tool including an acoustic system configured to measure an acoustic property of the droplet removal system and / or the liquid,

[0025] wherein the acoustic system includes a transducer configured to emit acoustic waves into the liquid and / or receive acoustic waves from the liquid.

[0026] Other embodiments, features and advantages of the present invention, and the structure and operation of the various embodiments, features and advantages of the present invention are described in detail below with reference to the accompanying drawings. Description of the Drawings

[0027] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic diagrams, in which corresponding reference numerals indicate corresponding parts, and in which:

[0028] Figure 1 A schematic overview of a lithographic apparatus is depicted;

[0029] Figure 2a 、 2b 、2c and 2d depict in cross-section two different versions of a fluid handling system that can extend around an entire circumference, with different features illustrated on the left-hand side and the right-hand side of each version;

[0030] Figure 3a and 3b Schematically illustrate a part of a known fluid handling system in a first operating state and a second operating state, respectively;

[0031] Figure 4 Schematically illustrate a part of a known fluid handling system;

[0032] Figure 5 Schematically illustrate a part of a known fluid handling system;

[0033] Figure 6 Schematically illustrate the diagnostic tool of an embodiment;

[0034] Figure 7 is Figure 6 a graph of the acoustic signal response as a function of frequency in a diagnostic tool;

[0035] Figure 8 schematically shows in cross-section a part of a fluid handling system including the diagnostic tool of the embodiment;

[0036] Figure 9 schematically shows in a plan view a part of a fluid handling system including the diagnostic tool of the embodiment; and

[0037] Figure 10 schematically shows in cross-section a fluid handling system including the diagnostic tool of the embodiment.

[0038] The features shown in the drawings are not necessarily drawn to scale, and the depicted dimensions and / or arrangements are not restrictive. It is to be understood that the drawings include optional features that may not be essential to the invention. In addition, not all features of the device are depicted in each of the drawings, and the drawings may only show some of the components relevant to the description of a particular feature. Detailed Description

[0039] In this document, the terms "radiation" and "beam" are used to cover all types of electromagnetic radiation, including ultraviolet radiation (e.g., having a wavelength of 365, 248, 193, 157 or 126 nm).

[0040] The terms "reticle", "mask" or "patterning device" as used herein can be broadly interpreted to refer to a general patterning device that can be used to impart a patterned cross-section to an incident radiation beam, which patterned cross-section corresponds to a pattern to be created 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 LCD arrays in addition to classical masks (transmission or reflection masks, binary masks, phase-shift masks, hybrid masks, etc.).

[0041] Figure 1Schematically depicts a lithographic apparatus. The lithographic apparatus includes: an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam B (e.g., UV radiation or DUV radiation); a mask support (e.g., a mask table) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA according to certain parameters; a substrate support (e.g., a substrate table) WT constructed to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioner PW configured to accurately position the substrate support WT according to certain parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., 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 various subsystems of the lithographic apparatus.

[0042] In operation, the illumination system IL receives the radiation beam B from a radiation source SO, for example via a beam delivery system BD. The illumination system IL can include various types of optical components for directing, 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 plane of the patterning device MA in its cross-section.

[0043] The term "projection system" PS as used herein should be broadly interpreted to cover various types of projection systems, including refractive, reflective, refractive-reflective, 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. Any use of the term "projection lens" herein can be considered synonymous with the more general term "projection system" PS.

[0044] The lithographic apparatus is of the type in which at least a portion of the substrate W can be covered by an immersion liquid (e.g., water) having a relatively high refractive index so as to fill an immersion space 11 between the projection system PS and the substrate W, which is also referred to as immersion lithography. More information on immersion techniques is given in US 6,952,253, which is incorporated herein by reference.

[0045] A lithographic apparatus may be of the type having two or more substrate supports WT (also known as "dual stage"). In such a "multi-stage" machine, the substrate supports WT can be used in parallel, and / or steps of preparing a substrate W for a subsequent exposure of a substrate W located on one of the substrate supports WT can be carried out while another substrate W on another substrate support WT is being used for exposing a pattern on another substrate W.

[0046] In addition to the substrate support WT, the lithographic apparatus may include a measurement stage (not depicted in the figures). The measurement stage is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure properties of the projection system PS or of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning device may 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. The measurement stage may move under the projection system PS when the substrate support WT is moved away from the projection system PS.

[0047] In operation, the radiation beam B is incident on a patterning device (e.g., a mask) MA held on a mask support MT and is patterned by the pattern (design layout) present on the patterning device MA. After passing through the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. By means of a second positioner PW and a position measurement system IF, the substrate support WT can be accurately moved, for example, in order 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 (not explicitly depicted in Figure 1 the figures) can be used to accurately 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 illustrated substrate alignment marks P1, P2 occupy dedicated target portions, the substrate alignment marks P1, P2 may be located in the space 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.

[0048] To clarify 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 the three axes is orthogonal to the other two axes. A rotation about the x-axis is called an Rx rotation. A rotation about the y-axis is called an Ry rotation. A 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 the vertical direction. The Cartesian coordinate system does not limit the present invention but is only used to clarify it. Instead, another coordinate system (such as a cylindrical coordinate system) can be used to clarify 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.

[0049] Immersion technology has been introduced into a lithography system to achieve improved resolution of smaller features. In an immersion lithography apparatus, a liquid layer of an immersion liquid having a relatively high refractive index is interposed in an immersion space 11 between a projection system PS (through which a patterned beam is projected toward a substrate W) of the apparatus and the substrate W. Thus, at least a part of the substrate W that is undergoing exposure is immersed in the immersion liquid.

[0050] In commercial immersion lithography, the immersion liquid is water. Generally, the water is highly purified distilled water, such as ultrapure water (UPW) that is commonly used in semiconductor fabrication plants. In an immersion system, the UPW is often purified, and the UPW can undergo additional processing steps before being supplied as the immersion liquid to the immersion space 11. In addition to water, other liquids having a high refractive index can also be used as the immersion liquid, for example: hydrocarbons (such as fluorocarbons); and / or aqueous solutions. Further, it has been envisioned to use other fluids besides liquids for immersion lithography.

[0051] In the present specification, localized immersion will be mentioned in the description, in which the immersion liquid is restricted to the immersion space 11 between a final element 100 and a surface facing the final element 100 during use. The facing surface is the surface of the substrate W or a surface of a support table (or substrate support WT) that is coplanar with the surface of the substrate W. (Note that hereinafter a reference to the surface of the substrate W also additionally or alternatively refers to the surface of the substrate support WT, unless otherwise explicitly stated, and vice versa). A fluid handling structure 12 present between the projection system PS and the substrate support WT is used to restrict the immersion liquid to 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 plan view, and the immersion space 11 remains substantially stationary relative to the projection system PS while the substrate W and the substrate support WT move therebelow.

[0052] Other immersion systems have been envisioned, such as non - restrictive immersion systems (so - called 'fully - wet' immersion systems) and bathtub - type immersion systems. In non - restrictive immersion systems, the immersion liquid covers an area larger than the surface under the final element 100. The liquid outside the immersion space 11 exists as a thin liquid film. The liquid can cover the entire surface of the substrate W or even the substrate W and the substrate support WT coplanar with the substrate W. In bathtub - type systems, the substrate W is completely immersed in a bath of immersion liquid.

[0053] 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 thus confines the immersion liquid to the immersion space 11. The fluid handling structure 12 includes features as part of a fluid supply system. The arrangement disclosed in PCT patent application publication number WO 99 / 49504 is an early fluid handling structure that includes a pipe that supplies or recovers immersion liquid from the immersion space 11 and operates depending on the relative movement of the stage under the projection system PS. In a more recent 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 so as to partially define the immersion space 11.

[0054] The fluid handling structure 12 can have a selection of different functions. Each function can be derived from the corresponding features that enable the fluid handling structure 12 to perform that function. The fluid handling structure 12 can be referred to by many 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.

[0055] As a barrier member, the fluid handling structure 12 is a barrier to the flow of immersion liquid from the immersion space 11. As a liquid confinement structure, this structure confines the immersion liquid to the immersion space 11. As a sealing member, the sealing features of the fluid handling structure 12 form a seal for confining the immersion liquid to the immersion space 11. The sealing features can include additional gas flows (such as air knives) from the openings in the surface of the sealing member.

[0056] The fluid handling structure 12 can supply immersion fluid and thus form part of a fluid supply system.

[0057] The fluid handling structure 12 can at least partially confine the immersion fluid and thus form part of a fluid confinement system.

[0058] The fluid handling structure 12 can provide a barrier to the immersion fluid and thus is a barrier member, such as a fluid confinement structure.

[0059] The fluid handling structure 12 can create or use a gas flow, for example to assist in controlling the flow rate and / or position of the immersion fluid.

[0060] The gas flow can form a seal for confining the immersion fluid, and thus, the fluid handling structure 12 can be referred to as a sealing member; such a sealing member can be a fluid confinement structure.

[0061] An immersion liquid can be used as the immersion fluid. In this case, the fluid handling structure 12 can be a liquid handling system. In the context of referring to the foregoing description, references in this paragraph to features defined with respect to a fluid can be understood to include features defined with respect to a liquid.

[0062] A lithographic apparatus has a projection system PS. During the exposure of a 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 passes from the projection system PS through an immersion liquid, which is confined between the projection system PS and the substrate W by the fluid handling structure 12. The projection system PS has a lens element that is in contact with the immersion liquid, and this lens element is the last element in the beam path. This lens element in contact with the immersion liquid can 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 can confine the immersion liquid below the final element 100 and above the facing surface.

[0063] Figure 2a 、 2b 、2c and 2d illustrate different features that may be present in variations of the fluid handling system. Unless described otherwise, these designs can share some of the same features with Figure 2a 、 2b 、2c and 2d. The features described herein can be selected individually or in combination, as shown or as required. These figures depict different versions of the fluid handling system, with different features illustrated on the left and right sides, and these features can extend around the entire circumference. Thus, for example, the fluid handling system can have the same features extending around the entire circumference. For example, the fluid handling system can have only Figure 2a the left side of Figure 2a 、or Figure 2b the right side of Figure 2b 、or

[0064] Figure 2a the left side of Figure 2b 、or

[0064] Figure 2a the right side of Figure 2b 、or

[0064] Figure 2a the left side of 2c, or Figure 2b 、or

[0064] Figure 2a the right side of 2c, or Figure 2b 、or

[0064] Figure 2a the left side of 2d or Figure 2b 、or

[0064] Figure 2a the right side of 2d. 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 as described in the variations below.

[0064] Figure 2aA fluid handling system is shown, which includes a fluid handling structure 12 around the bottom surface of a final element 100. The final element 100 has an inverted frustoconical shape. The frustoconical shape has a planar bottom surface and a conical surface. The frustoconical shape projects from the planar surface and has a bottom planar surface. The bottom planar surface is the optically active portion of the bottom surface of the final element 100 through which a radiation beam B can pass. The final element 100 may have a coating 30. The fluid handling structure 12 surrounds at least a portion 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 planar. The fluid handling structure 12 may be assembled around the frustoconical shape of the final element 100. The bottom surface of the fluid handling structure 12 may be substantially planar, and in use, the bottom surface may 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 may be referred to as the surface facing the substrate W surface. 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.

[0065] 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, an immersion space 11 is defined between the inner surface of the fluid handling structure 12, the planar surface of the frustoconical portion, and the facing surface. During use, the immersion space 11 is filled with an immersion liquid. The immersion liquid fills at least a portion of the buffer space between the complementary surfaces between the final element 100 and the fluid handling structure 12, such as at least a portion of the space between the complementary inner surface and the conical surface.

[0066] 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 may be supplied through a supply opening 20 in the inner surface of the fluid handling structure 12. Alternatively or additionally, the immersion liquid is supplied from a lower supply opening 23 formed in the bottom surface of the fluid handling structure 12. The lower supply opening 23 may surround the path of the radiation beam B, and it may be formed by a series of openings or a single slit in an array. The immersion liquid is supplied to fill the immersion space 11 such that the flow through the immersion space 11 below 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. Such a supply of the immersion liquid may be used as a liquid seal.

[0067] 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 achieved by applying a negative pressure; due to the velocity of the immersion liquid flowing through the immersion space 11, the recovery through the recovery opening 21; or the recovery may be the result of both. When viewed in a plane, 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 by an overflow recovery member 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 flow direction to be changed depending on the relative movement of the fluid processing structure 12 and the substrate W.

[0068] Additionally or alternatively, the immersion liquid can be recovered from below the fluid processing structure 12 through a recovery opening 25 formed in its bottom surface. The recovery opening 25 can be used to hold the meniscus 33 of the immersion liquid to the fluid processing structure 12. The meniscus 33 is formed between the fluid processing structure 12 and the facing surface, and it serves as a boundary between the liquid space and the gas external environment. The recovery opening 25 can be a porous plate, which can recover the immersion liquid in a substantially single-phase flow. The recovery opening in the bottom surface can be a series of pinning openings 32 through which the immersion liquid is recovered. The pinning openings 32 can recover the immersion liquid in a two-phase flow.

[0069] Optionally radially outward relative to the inner surface of the fluid processing 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 the liquid confinement of the immersion liquid in the immersion space 11. The supplied gas can be humidified, and it can contain a large amount of carbon dioxide. Radially outward of the air knife opening 26 is a gas recovery opening 28 for recovering the gas supplied through the air knife opening 26.

[0070] In the bottom surface of the fluid processing structure 12 (i.e., the surface of the fluid processing structure 12 facing the substrate W), there can be other openings, such as openings to the atmosphere or a gas source or a vacuum. Figure 2a An example of such an optional additional opening 50 is shown in dashed lines on the right side. As shown, the additional opening 50 can be a supply or extraction member, as indicated by the double-headed arrow. For example, if configured for supply, the additional opening 50 can be connected to a liquid supply or a gas supply in the same way as any supply member. Alternatively, if configured for extraction, the additional opening 50 can be used to extract fluid, and for example, it can be connected to the atmosphere or a gas source or a vacuum. For example, at least one additional opening 50 can be 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.

[0071] Figure 2aTwo different versions of the fluid handling structure 12 on the left and right pin the meniscus 33. Due to the fixed position of the pinning opening 32, Figure 2a The version of the fluid handling structure 12 on the right can pin the meniscus 33 at a position that is substantially fixed relative to the final element 100. Figure 2a The version of the fluid handling structure 12 on the left can pin the meniscus 33 below the recovery opening 25, so the meniscus 33 can move along the length and / or width of the recovery opening 25. To direct the radiation beam B to all sides of the substrate W being exposed, the substrate support WT supporting the substrate W is moved relative to the projection system PS. 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 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, for example in the form of one or more droplets. In addition, an unstable meniscus 33 has a greater risk of causing bubbles to be included in the immersion liquid, especially when the confined immersion liquid passes through the edge of the substrate W.

[0072] Droplets present on the surface of the substrate W can impose a heat load and can be a source of defects. The droplets can evaporate, leaving dry stains, which can transport contaminants such as particles, which may collide with a larger immersion liquid entity, thereby introducing bubbles into the larger entity, and the liquid entity can evaporate, thereby imposing a heat load on the surface where the liquid entity is located. If the surface is associated with the positioning of the components of the lithographic apparatus relative to the substrate W being imaged, such a heat load can be a cause of distortion 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 thus limited to the critical scan speed at which the meniscus 33 remains stable. This limits the throughput of the lithographic apparatus.

[0073] Figure 2a The left hand side of the fluid handling system in can include a spring 60. The spring 60 can 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 means may also be suitable, such as using electromagnetic forces. Although the spring 60 is shown on the Figure 2a left side, it is optional and does not need to be included together with the Figure 2a Other features on the left side. The spring 60 is not shown on any other drawings, but can also be associated with Figure 2a 、2b Other variations of the fluid handling system described in 2c or 2d are included together.

[0074] Figure 2b A fluid handling system is shown, with two different versions of the fluid handling structure 12 shown on its left and right sides, which allows 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, whereby stability can be increased and the risk of the meniscus 33 breaking can be reduced. The speed of the substrate W in the case of the meniscus 33 breaking is increased to allow the substrate W to move faster under the projection system PS. Thus, the throughput is increased.

[0075] Figure 2b The features shown in common with Figure 2a share 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 bottom planar surface of the frustoconical shape.

[0076] 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 located at 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, spaced apart around the path of the radiation beam B.

[0077] 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 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 contained in a chamber 35 within the fluid handling structure 12, where it is separated into liquid and gas. The liquid and gas are recovered from the chamber 35 through separate channels 36, 38.

[0078] The inner peripheral edge 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 peripheral edge 39 forms small holes, the size of which can be formed to 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 it. The supplied immersion liquid flows inward towards the holes, through these internal holes, and then under the plate 40, flowing radially outward towards the surrounding recovery openings 25.

[0079] The fluid handling structure 12 can be as Figure 2bShown on the right - hand side is a two - component form: an internal component 12a and an external component 12b. The internal component 12a and the external component 12b can move relative to each other, mainly in a plane parallel to the facing surface relative to each other. The internal component 12a can have a supply opening 34, and it can have an overflow recovery member 24. The external component 12b can have a plate 40 and a recovery opening 25. The internal component 12a can have an intermediate recovery member 42 for recovering the immersion liquid flowing between the internal component 12a and the external component 12b.

[0080] 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, thus achieving a faster scan speed and an increased throughput of the lithography apparatus. However, the migration speed of the meniscus 33 on the surface of the recovery opening 25 in the fluid handling structure 12 on the Figure 2b left - hand side may be slow. Figure 2b The fluid handling structure 12 on the right - hand side allows the meniscus 33 to move faster by moving the external component 12b relative to the internal component 12a and the final element 100. However, it may be difficult to control the intermediate recovery member 42 to ensure that there is sufficient immersion liquid between the internal component 12a and the external component 12b to prevent contact between them.

[0081] Figure 2c A fluid handling system is shown, with two different versions of the fluid handling structure 12 shown on its left - hand side and right - hand side. The fluid handling system can be used to pin the meniscus 33 of the immersion liquid to the fluid handling structure 12, as described above with respect to Figure 2a and / or 2b. Figure 2c Features shown in common with Figure 2a and / or 2b share the same reference numerals.

[0082] The fluid handling structure 12 has an inner surface complementary to a conical surface of a frustum - cone shape. The bottom surface of the fluid handling structure 12 is closer to the facing surface than the bottom planar surface of the frustum - cone shape. The immersion liquid is supplied to the immersion space 11 and is transported 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 is supplied through the lower supply opening 23. The immersion liquid can be recovered via a pumping member, for example, via the recovery opening 21 formed in the inner surface and / or the overflow recovery member 24 and / or one or more openings in the surface of the fluid handling structure 12, as described below.

[0083] Figure 2cTwo different versions of the fluid handling structure 12 on the left and right hand sides pin the meniscus 33. Due to the fixed position of the recovery opening 32a, Figure 2c The version of the fluid handling structure 12 on the right hand side can pin the meniscus 33 at a position that is substantially fixed relative to the final element 100. Figure 2c The version of the fluid handling structure 12 on the left hand side can pin the meniscus 33 below the recovery opening 25, such that the meniscus 33 can move along the length and / or width of the recovery opening 25.

[0084] As described above with respect to Figure 2b As described, the inner peripheral edge of the bottom surface of the fluid handling structure 12 can extend away from the inner surface into the immersion space 11 to form the plate 40 shown on the left hand side. As described above, this can form small holes and can isolate the immersion liquid on either side and / or cause the immersion liquid to flow inwards towards the holes, through the inner holes, and then radially outwards below the plate 40 towards the surrounding recovery opening 25. Although this feature is shown on the Figure 2c left hand side, it is optional in combination with the other features shown. Preferably, as shown on the left hand side, 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 located at the bottom of the inner surface, possibly below the bottom surface of a frustoconical shape. The supply openings 34 are located around the inner surface, spaced apart around the path of the radiation beam B. 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. Although the supply opening 34 is the preferred liquid supply, any combination of the supply opening 34, the supply opening 20, and / or the lower supply opening 23 can be provided.

[0085] As Figure 2c shown on the left hand side, the fluid handling system can include the above-described fluid handling structure 12 and an additional device 3000. The fluid handling structure 12 can have a pumping member (such as the recovery opening 25) and a liquid supply opening (such as the lower supply opening 23). It is to be understood that the fluid handling structure 12 can include any configuration disclosed in combination with the additional device 3000 with respect to Figure 2a the left hand side, Figure 2a the right hand side, Figure 2b the left hand side, Figure 2b the right hand side, or (as described below) Figure 2c the right hand side.

[0086] Additionally, the additional device 3000 may be referred to as a droplet trap. The additional 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 entire surface. The additional 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 shape of the at least one supply member 3010 in a plan view. The at least one liquid supply member 3010 may be configured to supply additional liquid to the space 3110 between at least a portion of the additional device 3000 and the surface of the substrate W. The additional device 3000 may be configured to recover at least some of the liquid via the at least one extraction member 3020. The additional 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 additional device 3000, thereby reducing the amount of liquid remaining on the surface of the substrate W.

[0087] In Figure 2c it, the additional device 3000 is shown as a device separate from the fluid handling structure 12. The additional device 3000 may be positioned adjacent to the fluid handling structure 12. Alternatively, the additional device 3000 may be part of the fluid handling structure 12, i.e., integrated with the fluid handling structure 12 (as shown in FIG. 3d, but either arrangement may be chosen).

[0088] The additional device 3000 may be configured to supply liquid to the space 3110 that is separate from the liquid provided by the fluid handling structure 12.

[0089] Additionally or alternatively, the fluid handling structure 12 may have Figure 2c the components shown on the right hand side. More specifically, the fluid handling structure 12 may include at least one liquid supply member, two extraction members (such as recovery openings 32a and 32b), and two gas supply members (such as gas supply openings 27a and 27b) formed on the surface of the fluid handling structure 12. The gas supply opening 27a may be omitted, i.e., 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 with respect to Figure 2b the left hand side. 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.

[0090] At least one of the two extraction members may include a porous material 37 therein. The porous material 37 may be provided within an opening such as the recovery opening 32a through which the fluid handling structure 12 extracts fluid from below the fluid handling structure 12 and may recover the immersed liquid in a single-phase flow. The other extraction member of the two extraction members (such as the recovery opening 32b) may recover the immersed fluid as a two-phase extractor. The porous material 37 need not be flush with the bottom surface of the fluid handling structure 12.

[0091] Specifically, the fluid handling structure 12 may include a liquid supply member (such as the lower supply opening 23), a first extraction member radially outward of the liquid supply member (such as the recovery opening 32a), a first gas supply member radially outward of the first extraction member (such as the gas supply opening 27a), a second extraction member radially outward of the first gas supply member (such as the recovery opening 32b), and a second gas supply member radially outward of the second extraction member (such as the gas supply opening 27b). And Figure 2a Similarly, as previously described, there may be other openings in the bottom surface of the fluid handling structure 12, such as openings that open to the atmosphere or a gas source or a vacuum (associated with the fluid handling structure 12).

[0092] 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. As described in the above arrangement, the additional opening may be arranged between the first extraction member (such as the recovery opening 32a) and the first gas supply member (such as the gas supply opening 27a). Alternatively or additionally, as described in the above arrangement, the additional opening may be arranged between the second extraction member (such as the recovery opening 32b) and the second gas supply member (such as the gas supply opening 27b). The additional opening may be the same as the above-mentioned additional opening 50.

[0093] 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 2cAs shown. In a 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 the inclined surface of the fluid processing structure 12, or on a part of the bottom surface of the fluid processing 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 processing structure 12. The shape of the recess 29 may be varied to change the influence of the gas supplied from the gas supply member on the fluid below the fluid processing structure 12.

[0094] Figure 2d A fluid processing system is shown, with its left and right halves showing two different versions of the fluid processing structure 12. Figure 2d The fluid processing structure 12 in the left half has a liquid injection buffer 41a that holds a buffer amount of the immersion liquid and a liquid injection hole 41 that supplies the immersion liquid from the liquid injection buffer to the space 11. Outside the liquid injection hole 41 is an internal liquid recovery hole 43 for leading the liquid into the internal recovery buffer 43a provided with a porous member. An indentation 29 similar to that Figure 2c described is provided outward of the internal liquid recovery hole 43. Outside the recess 29, in the lower surface of the fluid processing structure 12 is a gas guiding groove 44, and an external recovery hole 44a opens into the gas guiding groove 44. The external recovery hole 44a guides the two-phase recovery flow to the external recovery buffer 44b that is also provided with a porous member. The outermost is a gas sealing hole 45 that communicates between the gas sealing buffer volume 45a and the space below the fluid processing structure 12 to provide a gas flow to restrict the immersion liquid.

[0095] Figure 2d The fluid processing structure 12 in the right half has a liquid supply opening 20 on its inner inclined surface. On the lower side (from the inside to the outside) of the fluid processing structure 12 are provided an extraction opening 25 provided with 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 opens into a groove on the lower side of the fluid processing structure 12 that provides a buffer volume. The outermost part of the fluid processing structure 12 is stepped to provide a greater spacing between the fluid processing structure 12 and the substrate W.

[0096] Figures 2a to 2dIllustrates examples of different configurations that can be used as part of a fluid handling system. It is to be understood that the examples provided above relate to specific extraction members and recovery members, but it is not necessary to use exactly the same type of extraction members and / or recovery members. In some cases, different terms are used to indicate the location of the members, but the same functional characteristics can be provided. Examples of the extraction members mentioned above include recovery opening 21, overflow recovery member 24, recovery opening 25 (which may include a perforated plate and / or chamber 35), gas recovery opening 28, pinning opening 32, recovery opening 32a, recovery opening 32b, and / or intermediate recovery member 42. Examples of the supply members mentioned above include supply opening 20, lower supply opening 23, air knife opening 26, gas supply opening 27a, gas supply opening 27b, and / or supply opening 34. Generally, the extraction members for extracting / recovering fluid, liquid, or gas can be interchanged with at least any other examples that respectively extract / recover fluid, liquid, or gas. Similarly, the supply members for supplying fluid, liquid, or gas can be interchanged with at least any other examples that are used to respectively supply fluid, liquid, or gas. The extraction members can extract / recover fluid, liquid, or gas from a space by connecting to a negative pressure that draws the fluid, liquid, or gas into the extraction members. The supply members can supply fluid, liquid, or gas to the space by connecting to a relevant supply.

[0097] As previously described, while using an immersion fluid / liquid is beneficial for improving the resolution of smaller features on a substrate, there are also challenges associated with using an immersion fluid / liquid related to defects introduced on the substrate.

[0098] Generally, when using an immersion liquid, 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 a droplet impacts the meniscus 33, gas may be trapped within the immersion liquid. This results in the formation of bubbles in the immersion liquid. The formation of bubbles in the immersion liquid may cause defects on the substrate W. The droplets remaining on the surface of the substrate W may cause dry spots and / or affect the chemical properties of the resist, and may also cause defects.

[0099] Figure 3a and 3b Shows a part of a fluid handling system 301. The fluid handling system 301 can confine the immersion liquid to a liquid confinement space or immersion space 11 located between a part of the projection system PS and the surface of the substrate W. The immersion liquid can be any of the above immersion fluids. For example, the immersion liquid can be water. The radiation beam B projected from the projection system PS can irradiate the surface of the substrate W through the immersion liquid.

[0100] Figure 3aOnly a part of the fluid handling system 301 is shown, which includes a liquid confinement structure that supports the meniscus 310 of the immersion liquid. The meniscus 310 forms a boundary between the immersion liquid and the surrounding environment of the fluid handling system 301. Although Figure 3a not shown in, the main part of the fluid handling system 301 is in the direction indicated by the arrow 306. The main part of the fluid handling system 301 may include the immersion liquid and may include any part of the various structures disclosed above with reference to Figures 2a to 2d , or indeed any other system that positions the immersion liquid below the projection system PS. In particular, the main part of the fluid handling system 301 may include an immersion space, such as the immersion space 11 described with reference to Figures 2a to 2d .

[0101] As Figure 3a shown, the fluid handling system 301 is arranged above the substrate W. The substrate W may include a wafer 305 and a resist coating 304 on the wafer 305. There is a channel 308 between the fluid handling system 301 and the substrate W. The part of the channel 308 between the main part of the fluid handling system 301 in the direction 306 and the meniscus 310 may include the immersion liquid. The part of the channel 308 in the direction 307 between the meniscus 310 and the external environment of the fluid handling system 301 may include gas.

[0102] The fluid handling system 301 includes a first pumping member 302. The first pumping member 302 includes a first pumping pipe 302b. The first pumping pipe 302b is a fluid pipe and may provide a flow of immersion liquid flowing out of the fluid handling system 301. The first pumping member 302 further includes a first pumping opening 302a arranged in the upper surface of the channel 308. The first pumping opening 302a is the end of the first pumping pipe 302b.

[0103] The fluid handling system 301 includes a second pumping member 303. The second pumping member 303 includes a second pumping pipe 303b. The second pumping pipe 303b is a pipe for a fluid (such as gas). The second pumping member 303 further includes a second pumping opening 303a arranged in the upper surface of the channel 308. The second pumping opening 303a is the end of the second pumping pipe 303b.

[0104] There is an upper surface of the channel 308 between the first pumping member 302 and the second pumping member 303, which is referred to herein as the damper 311. The length of the damper 311 defines the spacing between the first pumping member 302 and the second pumping member 303 along the length of the channel 308.

[0105] The first extraction member 302 can be configured to extract the immersion liquid through the fluid flow 309. The only fluid flow through the first extraction member 302 can be substantially the fluid flow 309 of the immersion liquid. However, the first extraction member 302 can also extract some gas from the external environment of the fluid processing system 301. Therefore, the fluid flow through the first extraction member 302 can be a two-phase flow. When there is a fluid flow through the first extraction member 302, a gas flow 314 through the second extraction member 303 can exist simultaneously.

[0106] The second extraction member 303 can be configured to extract gas from the channel 308. Figure 3b The gas flow 314 for gas extraction is shown. The gas flow 314 can create a negative pressure in the channel 308.

[0107] Although Figure 3a and 3b are not shown, the main part of the fluid processing system 301 in the direction 306 can include a fluid processing structure having an inner surface, which is configured to confine the immersion liquid. The first extraction member 302 and the second extraction member 303 are radially away from the main part of the fluid processing system 301. The second extraction member 303 can be farther from the inner surface of the fluid processing structure than the first extraction member 302. Alternatively, the first extraction member 302 and the second extraction member 303 can be part of the main part of the fluid processing system 301. The second extraction member 303 can be farther from the midpoint of the fluid processing system 301 than the first extraction member 302.

[0108] The first operating state of the fluid processing system 301 is as Figure 3a shown. In the first operating state, there may be no relative movement between the substrate W and the fluid processing system 301. The first extraction member 302 can be configured such that when in the first operating state, the amount of the immersion liquid extracted through the first extraction member 302 does not substantially exceed the amount required to keep the meniscus 310 at substantially the same position along the channel 308. When there is no relative movement between the substrate W and the fluid processing system 301, the fluid flow rate through the first extraction member 302 is substantially the minimum flow rate capable of keeping the meniscus 310 stationary.

[0109] The second operating state of the fluid processing system 301 is as Figure 3b shown. In the second operating state, the substrate W can move relative to the fluid processing system 301. The second operating state includes a scanning movement along the scanning direction. The scanning direction can be substantially perpendicular to the propagation direction of the radiation beam B. The scanning direction can be Figure 3bThe direction 312 shown. It should be noted that the second operating state may also include other relative movements between the substrate W and the fluid handling system 301 in addition to the scanning movement. For example, the second operating state may include a preparatory movement before the scanning movement.

[0110] The first extraction member 302 may be configured such that the amount of immersion liquid extracted through it is substantially the same in the first operating state and the second operating state. The movement of the substrate W in the direction 312 generates a shear force on the immersion liquid in the channel 308. Therefore, the meniscus 310 moves along the channel 308 in the direction 313. The increased flow rate of the immersion liquid entering the channel 308 can be referred to as Couette flow and can also be referred to as shear-driven flow or pressure-driven flow. The generation of negative pressure in the channel 308 by the gas flow 314 also supports the movement of the meniscus 310 along the channel 308.

[0111] In the second operating state, the meniscus 310 is not held stationary by the fluid flow through the first extraction member 302. When there is no relative movement between the fluid handling system 301 and the substrate W, the fluid flow through the first extraction member 302 is only sufficient to keep the meniscus 310 stationary. Therefore, in the second operating state, the meniscus 310 moves along the channel 308.

[0112] Advantageously, the maximum tolerable relative movement speed between the fluid handling system 301 and the substrate W increases. The relative movement speed between the meniscus 310 and the substrate W can be lower than or equal to the critical scanning speed so that no significant droplet formation occurs. The relative movement speed between the fluid handling system 301 and the meniscus 310 increases the relative movement speed between the fluid handling system 301 and the substrate W. The relative movement speed between the fluid handling system 301 and the substrate W can be up to twice the critical scanning rate of a known system where the meniscus 310 is substantially stationary within the channel 308.

[0113] The damper 311 may be configured such that its surface properties support the proper movement of the end of the meniscus 310 along the damper 311. In particular, the surface of the damper 311 may be coated or otherwise configured such that it has any one of hydrophobicity, hydrophilicity, or porosity.

[0114] The surface of the damper 311 may be configured such that it is substantially parallel to the surface of the substrate W. Alternatively, the surface of the damper 311 may be curved or inclined away from the surface of the substrate W. That is, the first end of the surface of the damper 311 is at the first extraction member 302, and the second end of the surface of the damper 311 is at the second extraction member 303. The surface of the damper 311 may be configured such that the spacing between the surface of the damper 311 and the surface of the substrate W is greater at the second end than at the first end.

[0115] The above damper 311 can be referred to as the first damper 311. As at least Figure 3a and 3b shown, the fluid handling system 301 can include a second damper 315. The surface of the second damper 315 is the length of the upper surface of the channel 308 on the other side of the first extraction member 302 relative to the first damper 311. The second damper 315 can be configured such that the immersion liquid is supported between the surface of the second damper 315 and the surface of the substrate W.

[0116] The surface of the second damper 315 can be parallel to the surface of the substrate W. The spacing between the surface of the second damper 315 and the surface of the substrate W can be the same as the spacing between all or at least a part of the surface of the first damper 311 and the surface of the substrate W. Alternatively or additionally, the spacing between all or at least a part of the surface of the first damper 311 and the surface of the substrate W can be greater than the spacing between at least a part of the surface of the second damper 315 and the surface of the substrate W.

[0117] The upper surface 316 of the channel 308 starting from the second extraction member 303 and extending in the direction 307 to the external environment of the fluid handling system 301 can be parallel to the surface of the substrate W. Alternatively, the upper surface 316 of the channel 308 can be inclined / bent such that the spacing between the upper surface 316 of the channel 308 and the surface of the substrate W changes. The gas pressure in the channel 308 may depend on the shape of the upper surface 316. The shape of the surface 316 can be determined so as to generate an appropriate gas pressure in the channel 308 to support the movement of the meniscus 310 under the expected operating conditions.

[0118] The meniscus control surface can allow two different operating states. In the first operating state, liquid is extracted through the meniscus control surface such that the meniscus remains stationary within the channel 308, i.e., the meniscus 310 is pinned to the meniscus control surface. In the second operating state, substantially no liquid is extracted through the meniscus control surface such that the meniscus 310 can move along the channel 308 as described above with reference to Figure 3a and 3b described.

[0119] When long-distance high-speed movement is required, the first operating state is used such that a long damper is not required. In the first operating state, the speed of the relative movement between the substrate W and the fluid handling system 301 can be limited to below the speed at which a large number of droplets form on the substrate W. When high-speed movement over a short distance is required, the second operating state is used. In the second operating state, due to the movement of the meniscus 310, the relative movement speed between the substrate W and the fluid handling system 301 may be faster than the speed in the first operating state.

[0120] Figure 4 Schematically shows a part of another fluid handling system 301, which includes a liquid confinement structure that is different from the liquid confinement structures described above with reference to Figure 3a and 3b and further includes a meniscus control surface 401. The meniscus control surface 401 is formed by the upper surface of the channel 308, i.e., it is located on the side of the channel 308 opposite to the substrate W.

[0121] The meniscus control surface 401 can be located next to the damper 311 and between the first extraction member 302 and the second extraction member 303. The meniscus control surface 401 is preferably close to the first extraction member 302.

[0122] It should be noted that Figure 4 the meniscus control surface 401 is schematically shown and Figure 4 not drawn to scale. The meniscus control surface 401 is preferably much shorter than the damper 311. For example, the length of the meniscus control surface 401 can be between about 1 mm and 10 mm, and preferably less than 5 mm. The length of the damper 311 can be about 20 mm to 50 mm or longer.

[0123] The meniscus control surface 401 can be made of any of a variety of materials known in the art. For example, the meniscus control surface 401 can be made of metal or plastic. Preferably, the meniscus control surface 401 is coated such that its surface properties depend on the coating. In particular, a coating can be applied to make the meniscus control surface 401 hydrophilic. Preferably, the damper 311 is configured such that its surface is hydrophobic. These surface properties of the meniscus control surface 401 and the damper 311 support different first and second operating states, as described in detail later.

[0124] The meniscus control surface 401 can be the surface of a microsieve. The microsieve includes small openings that are arranged such that a fluid (such as an immersion liquid) can flow through them. On the side of the microsieve opposite to the channel 308, there can be a bypass flow path. The bypass flow path can be arranged to provide a liquid flow along the side of the meniscus control surface 401 opposite to the substrate W. The bypass flow path can include a liquid inlet 402 that is configured to supply a liquid flow 403 to the bypass flow path. The bypass flow path can also include a liquid outlet 405 that is configured to provide a liquid flow 404 flowing out of the bypass flow path.

[0125] The bypass flow path can be arranged to wet the openings of the micro-sieve. That is, even when there is substantially no liquid flowing through the openings, the liquid flow along the bypass flow path can ensure that substantially all of the openings of the micro-sieve are covered by liquid. Thus, the micro-sieve can have a wetted surface in all operating states of the fluid handling system 301. The micro-sieve is preferably configured such that the liquid in its openings has a high capillary pressure.

[0126] Although Figure 4 not shown in, the fluid handling system 301 can also include a flow control system configured to control the flow rate of the liquid through the liquid outlet 405. The flow control system can include, for example, a variable displacement pump, a multi-way valve system that can apply different flow rate restrictions, or any other technique for controlling the flow rate of the liquid through the liquid outlet 405.

[0127] The liquid received at the liquid inlet 402 can be diverted from the same liquid supply as the main part of the fluid handling system 301. Alternatively, a separate liquid supply can be provided for the bypass flow path.

[0128] The flow control system can be configured to control the fluid handling system 301 to be in at least one of a first operating state and a second operating state.

[0129] In the first operating state, the flow control system can be configured to apply a negative pressure above the micro-sieve. The flow control system can be configured such that the flow rate of the liquid flow 404 flowing out of the liquid outlet 405 is greater than the flow rate of the supplied liquid flow 403 through the liquid inlet 402. The additional liquid in the liquid flow 404 flowing out of the bypass flow path is provided by the submerged liquid flow through the micro-sieve openings. The effect of the liquid flow through the micro-sieve is that the meniscus 310 is pinned to the surface of the micro-sieve. That is, the meniscus 310 of the submerged liquid remains substantially stationary between the surface of the micro-sieve and the surface of the substrate W. The flow control system is preferably configured such that in the first operating state, the underpressure applied above the micro-sieve is less than the capillary pressure of the micro-sieve openings. This ensures that all the openings of the micro-sieve remain wet in the first operating state.

[0130] The position of the micro-sieve is preferably close to the first extraction member 302 to reduce the overall wetting area when in the first operating state.

[0131] In the second operating state, the flow control system can be configured such that the flow control system applies a fluid underpressure to the openings of the micro sieve, which underpressure is less than the capillary pressure of the openings, preferably substantially less than the capillary pressure of the openings. The pressure difference across the micro sieve is preferably minimal and can be substantially zero. The liquid flow rate through the liquid outlet 405 can be substantially the same as the liquid flow rate through the liquid inlet 402. There may be substantially no immersed liquid or gas flowing through the openings of the micro sieve. If a small amount of liquid flows from the channel 308 through the micro sieve openings covering the liquid in the channel 308, then this can be compensated for by reducing the liquid extraction through the first extraction member 302.

[0132] In the second operating state, the meniscus 310 moves freely relative to the surface of the micro sieve and the surface of the damper 311. Thus, the fluid handling system 301 can operate with the movable meniscus, substantially as described in RD681087.

[0133] In the second operating state, the flow control system can alternatively be configured to apply a slight overpressure above the micro sieve such that a smaller liquid flow flows from the bypass flow path through the micro sieve into the channel 308. This can increase the tolerable moving speed of the substrate W relative to the fluid handling system 301 in the second operating state.

[0134] In the first operating state, the flow rate of the liquid flow 404 flowing out of the bypass flow path can be the first fluid flow rate. In the second operating state, the flow rate of the liquid flow 404 flowing out of the bypass flow path can be the second fluid flow rate. The first fluid flow rate can be greater than the second fluid flow rate.

[0135] Figure 4 The fluid handling system 301 shown in the middle part can be substantially the same as Figure 3a and 3b the part of the liquid handling system 301 shown.

[0136] Advantageously, providing the meniscus control surface 401 allows for proper control of the meniscus 310 when long movements are required. The advantage that the meniscus control surface 401 is wetted in all operating states is that substantially only liquid flows through the meniscus control surface 401 in all operating states. This single-phase flow does not exert a large force on the substrate W. Different operating states can also be switched quickly.

[0137] If the pinning of the meniscus 310 is alternatively performed at the first extraction member 302, then it is not possible to avoid both liquid and gas flowing through the first extraction member 302. This two-phase flow will increase the extraction force required to pass through the first extraction member 302 and exert a larger force on the substrate W. In addition, the time required to switch from the second operating state to the first operating state may exceed 100 ms.

[0138] Figure 5 Part of another fluid handling system 301' is schematically shown. This other fluid handling system 301' includes a liquid confinement structure, which differs from the fluid handling system 301 in that it does not have the first extraction member 302. In the fluid handling system 301', the meniscus control surface 401 additionally provides fluid extraction, while in the fluid handling system 301, fluid extraction is performed by the first extraction member 302.

[0139] In the fluid handling system 301', the fluid flow through the micro-sieve can increase by an amount substantially the same as the fluid flow through the first extraction member 302 in the fluid handling system 301. Due to the increased fluid flow through the micro-sieve, the fluid extraction through the liquid outlet 405 (i.e., the liquid flow 404 flowing out of the bypass flow path) can be increased similarly.

[0140] In the first and second operating states, if there is no first extraction member 302, the fluid flow rate can be appropriately changed. The operation of the fluid handling system 301 can be the same as that of the fluid handling system 301'.

[0141] Advantageously, there is no first extraction member 302 in the fluid handling system 301'. This reduces the footprint of the extraction member and also reduces costs.

[0142] In the above fluid handling systems 301, 301', the meniscus control surface 401 is a micro-sieve. The meniscus control surface 401 can be any other type of surface through which liquid can flow. For example, the meniscus control surface 401 can be a porous member, including micro-slits or including capillaries.

[0143] In the above fluid handling systems 301, 301', the first extraction member 302 and the second extraction member 303 are described. There can be multiple such first extraction members 302 and / or multiple such second extraction members 303. The multiple first extraction members 302 can be arranged around the midpoint of the fluid handling system 301. The multiple first extraction members 302 can be arranged in any configuration. For example, they can be in a circular, square, rectangular, or star-shaped configuration. The first extraction opening 302a of each first extraction member 302 can have any shape. For example, each first extraction opening 302a can be circular, square, rectangular, or slot-shaped. The multiple second extraction members 303 can be arranged around the midpoint of the fluid handling system 301. For example, they can be in a circular, square, rectangular, or star-shaped configuration. The configuration of the second extraction members 303 can be the same as or different from the configuration of the first extraction members 302.

[0144] Determining whether to use the first operating state or the second operating state, and the relative movement speed between the fluid handling system 301 and the substrate W in each operating state, may depend on many different circumstances. These can include the desired movement length, the type of process being performed, and the surface properties of the substrate W or the substrate support. For example, the use of the first operating state and the movement speed may depend on the hydrophobicity of the surface of the substrate W.

[0145] In the fluid handling systems 301, 301' described above, the bypass flow path essentially only includes a liquid flow. The bypass flow path can provide a fluid flow in which the fluid is a bubbly flow. That is, the fluid flow in the bypass flow path can include a liquid flow and a gas flow.

[0146] In the first operating state, the fluid handling systems 301, 301' include a flow control system configured to allow a small amount of gas to flow through the micro-sieve in addition to the immersion liquid flowing through the openings of the micro-sieve. This can allow a greater force to be applied to keep the meniscus 310 stationary relative to the surface of the micro-sieve.

[0147] In the fluid handling systems 301, 301' described above, the meniscus control surface 401 and the surface of the damper 311 are described as being located on the upper surface of the channel 308. In a typical configuration of a horizontally arranged substrate W, this surface would be the upper surface of the channel 308. However, the meniscus control surface 401 and the surface of the damper 311 can be arranged in a surface of the fluid handling system 301 that is substantially parallel to the surface of the substrate W. The surface of the substrate W is not limited to a horizontal arrangement.

[0148] As mentioned above, the entry of air bubbles into the immersion liquid and into the path of the projection beam is undesirable because this can cause imaging errors. The presence of air bubbles in the immersion liquid can be determined by the presence of characteristic stripes or circular imaging errors in the exposed substrate. However, it is too late to take remedial measures at this time, and many substrates may be incorrectly exposed, thereby reducing the yield. Therefore, a diagnostic tool is proposed that can detect abnormal conditions in the fluid handling system, such as air bubbles and other contaminants, which may cause imaging errors early in the device manufacturing process. Advantageously, the diagnostic tool can take remedial measures before many substrates are incorrectly exposed.

[0149] The diagnostic tool can be implemented in any suitable fluid handling system, such as the fluid handling systems of the type described above. The diagnostic tool can be incorporated into the fluid handling system during the design phase, during manufacturing, or can be retrofitted. In some cases, as described below, additional advantages can be obtained by modifying the fluid handling system. The diagnostic tool can be used when the substrate is moving, such as during or between exposures, or when the substrate is stationary, such as during a calibration process or during maintenance of the lithographic apparatus.

[0150] The diagnostic tool can perform contamination diagnosis in the fluid handling structure 12 by listening to the acoustic characteristics of the fluid handling structure 12 and / or perform bubble detection in the immersion space 11 by listening to the acoustic characteristics of the immersion space 11. As Figure 6 shown, a diagnostic tool according to an embodiment of the present invention can include a transducer 601 configured to transmit an acoustic probe signal into the immersion liquid and detect an acoustic response or return signal (e.g., an echo) from the immersion liquid. The transducer 601 can be a piezoelectric device, such as being coupled to a diaphragm (not shown) in contact with the immersion liquid. The acoustic probe signal can be, for example, a swept frequency (e.g., chirp) or a pulse signal. The return signals from a plurality of pulses (e.g., about 10) can be integrated to obtain a sufficient signal-to-noise ratio.

[0151] The diagnostic tool works by treating the fluid handling structure 12 and / or the immersion space 11 as an acoustic system that has a characteristic fingerprint based primarily on its geometry (configuration and dimensions of channels, materials, etc.) and the presence / absence of bubbles. This characteristic changes due to the presence of solid or soft matter contaminants (e.g., foreign objects such as particles or fibers) and / or bubbles. Any such change can be detected, for example, by a signal analyzer, to determine whether an abnormal condition exists and / or to perform an analysis to diagnose the nature or cause of the abnormal condition. By using an appropriate acoustic model (in some cases only one-dimensional is required), various changes affecting the acoustics in the fluid handling structure 12 can be identified and, in some cases, precisely located. Changes affecting the acoustics can include blockages, which may change the effective area or volume of the system and can be regarded as a change in the boundary condition. Other changes affecting the acoustics can include compliance changes of system components (e.g., flexibility of the wall material) that affect the effective speed of sound in the system.

[0152] If an abnormal condition is detected or diagnosed, a remedial action can be performed, such as automatically. Depending on the nature of the detected abnormal condition, the remedial action can take various forms. If a bubble is detected, the remedial action can involve: pausing the exposure to allow the bubble to dissipate; increasing the fluid flow to wash away the bubble; reprocessing the already exposed substrate; modifying the scan parameters (such as route, speed, acceleration) of the current or subsequent exposure; performing one or more of manual cleaning or maintenance. If a contaminant is detected clogging or restricting the fluid flow, the remedial action can involve one or more of the following: increasing or reversing the fluid flow to expel the contaminant; modifying the scan parameters (such as route, speed, acceleration) of the current or subsequent exposure; operating an integrated cleaning device (such as a sticky wafer / substrate, a countercurrent system or an integrated cleaning station disclosed in US2011128516); performing manual cleaning or maintenance. Although performing manual cleaning or maintenance is undesirable as it reduces the availability of the equipment, it is preferred to perform the necessary manual cleaning or maintenance immediately after a major problem is detected and before too many substrates are incorrectly exposed. Thus, the present invention can provide advantages in terms of early detection and / or diagnosis of problems that negatively affect the exposure.

[0153] Figure 6 A configuration is depicted in which the characteristics of a fluid handling system including a fluid handling structure 12 are designed to assist in locating a detected abnormal condition, such as determining which hole or channel of the fluid handling system is affected. For purposes of illustration and explanation of the principle, Figure 6 is greatly simplified. An acoustic transducer 601 generates sound pulses (such as a swept frequency, such as a chirp or a simple pulse) that will cause the fluid handling structure 12 (including tubes, connection channels 200, main extraction channels, lower supply openings 23) to make an acoustic response. The acoustic response is converted back into an electrical signal by the transducer 601. The geometry, dimensions (and materials) of the components of the fluid handling structure 12 will determine the main resonance frequencies at which there will be a strong response in the received signal. By designing specific properties (such as hole size, tube length, cross-section, cross-section profile, etc.), a unique resonance frequency can be given to each component (such as the lower supply opening 23 or other passageways). Severe contamination will affect the resonance characteristics of the entire system and / or individual components. In the latter case, a change in amplitude and / or shift of a specific resonance (or phase change) will indicate a distortion or blockage of the component, i.e., the location of the contamination.

[0154] This is as Figure 7 shown, Figure 7 depicts the acoustic response (received pressure P in divided by the pressure output P out). The solid lines depict the nominal responses with different resonance peaks associated with specific components of the fluid handling structure 12, such as specific components in the lower supply opening 23. The dashed lines indicate the shift in the frequency response when contaminants are present, and the contaminants can then be localized to the components associated with the reduced or shifted resonance peaks.

[0155] It should be noted that the fluid handling structure 12 can have a very large number of components, and it may be possible to distinguish only a limited number of resonance peaks. In this case, only the selected components (such as the components most likely to experience contamination or the most critical components) can be tuned to have specific distinguishable resonances. A small number of components can also be tuned to each resonance frequency. In this case, identifying which resonance peak has changed isolates the location of the contamination to a small number of components, rather than just one component, but this is still useful compared to having no information about the presence or location of contamination and will save a significant amount of time during inspection and cleaning processes.

[0156] Due to, for example, the free surface at the immersed liquid end (meniscus), the immersed space 11 is not well-defined as an acoustic system. However, the significant acoustic resonance characteristics of bubbles can be used to detect bubbles that are freely floating in the immersed liquid or adhering to a surface (such as the surface of the substrate W). The assumption of negligible heat flow is shown to be a good approximation for freely oscillating bubbles, which gives the so-called Minneart resonance frequency:

[0157]

[0158] where R o is the equilibrium radius of the bubble, p0 is the hydrostatic pressure of the liquid outside the bubble, γ is the polytropic index, and ρ is the density of the surrounding liquid. For bubbles in an immersed liquid with a radius ranging from 10 to 100 µm, the expected resonance frequencies are in the range of 300 to 30 kHz, or more generally F M R o ≈ 3 mm.kHz. In some cases, more complex models, such as the Rayleigh Plesset equation, can be usefully employed.

[0159] To detect bubbles, the transducer 601 is controlled to emit a chirp signal and then listen for the response. This enables bubbles (and their size) to be detected very efficiently. The response frequency determines the size of the bubble, while the transmit / receive delay determines the travel distance to the transducer 601, since the speed of sound in the immersion liquid is well known. Using multiple transducers 601 at different locations in the fluid handling structure 12 also allows the position of bubbles in the immersion liquid to be determined. Knowing the position of the bubbles makes it possible to determine whether the bubbles are in the path of the exposure beam and thus whether remedial action is required. Repeated measurements give information on how the bubbles evolve over time (i.e., their position in time, but any change in size will also become visible from the shift in the resonance frequency). This may be used for diagnostic purposes.

[0160] Figure 8 and 9 is a simplified view of a fluid handling system including the fluid handling structure 12, showing possible positions of the transducer 601. Although only a single transducer 601 is shown, multiple transducers 601 may be provided, for example to be able to locate any bubbles 602. Desirably, the transducer positions are chosen so as not to interfere with any other function of the system and to maximize the sensitivity to the contaminants and / or bubbles to be detected. The fluid handling structure 12 is generally square (or linear) in plan view, while the immersion space 11 between the final element 100 and the substrate W is generally circular in plan view, so there is convenient space in the corners of the fluid handling structure 12 where (a) transducer(s) can be located.

[0161] Other effective positions for the transducer 601 include positions on the underside of the fluid handling structure 12 between the lower supply openings 23 within the lower supply openings 23. In a fluid handling structure 12 of the flow plate type (not shown in the drawings), the transducer 601 may be located below the flow plate, for example near a bend in the flow plate.

[0162] In a fluid handling structure 12 having a micro sieve, such as Figures 2a to 2c the recovery openings 25, 42 in, the diagnostic tool may be able to determine the condition of the micro sieve, for example determine the proportion of pores in the micro sieve that are blocked.

[0163] In most cases, the diagnostic tool will be most effective when the channel to be diagnosed is completely filled with only one liquid. Extraction channels that usually have two-phase flow can be diagnosed in a calibration mode, i.e., not during exposure, by supplying additional immersion liquid while the substrate holder is stationary relative to the fluid handling structure 12. Allow the additional immersion liquid to overflow the extraction channel and then slowly suck up the additional immersion liquid using the extraction channel while keeping the extraction channel filled with liquid during this operation.

[0164] The diagnostic tool according to the embodiment can provide more information about the origin and behavior of the bubbles 602 under exposure conditions. Such information can be obtained during actual exposure or during tests simulating actual exposure conditions. This information can allow for planning the exposure sequence and stage routes (such as speed, acceleration, direction changes) to avoid bubble defects. This information can be used to determine the parameters of the exposure configuration, such as: the moving speed of the substrate W; the acceleration of the substrate W; the moving direction of the substrate W; the height of the fluid handling system 12; or the flow rate of the immersion liquid. The insights obtained can also be applied to immersion lithography apparatuses without a diagnostic tool installed.

[0165] Another embodiment is as follows Figure 10 shown. Figure 10 The fluid handling system 301 can include Figure 3a , 3b some features of the above fluid handling systems 301, 301' of 4 and 5.

[0166] Figure 10 The embodiment of Figure 3a , 3b and 4 can be different because it includes a first extraction member 302 but does not include a second extraction member 303.

[0167] In Figure 10 the embodiment of, the movement of the meniscus 310 along the channel 308 can be passively supported by the inherent pressure generated in the channel 308 during operation. For example, surface tension may cause a negative pressure in the channel 308, and this negative pressure supports the movement of the meniscus 310 along the channel 308.

[0168] There may be a valve 701 on the first extraction pipe 302b for controlling the fluid flow rate through the first extraction member 302. The valve 701 improves the control of the fluid flow rate and / or pressure in the channel 308, thereby improving the control of the movement of the meniscus 310.

[0169] The above embodiments provide various designs of the fluid handling system 301 in which the meniscus 310 can move along the channel 308. One end of the meniscus 310 moves along the surface of the damper 311, and the other end of the meniscus 310 moves along the surface of the substrate W.

[0170] In a fluid handling system 301 in which the meniscus 310 moves, the fluid flow rate through the first pumping member 302 is less than the fluid flow rate in a fluid handling system in which the meniscus is pinned. In all operating conditions, when there is no relative movement between the fluid handling system 301 and the substrate W, the fluid flow rate through the first pumping member 302 does not substantially exceed the fluid flow rate required to keep the meniscus 310 stationary. Thus, when there is relative movement between the fluid handling system 301 and the substrate W, the meniscus 310 moves along the channel 308. Thus, the meniscus 310 can be supported between the damper 311 and the substrate W.

[0171] In a fluid handling system 301 in which the meniscus 310 moves, it is desirable to have information about the position of the meniscus 310 and / or the volume of the immersion liquid in the immersion space 11 between the liquid confinement structure and the surface of the substrate W. Such information may be useful during normal operation, calibration and setup, and / or maintenance of a lithographic apparatus. Such information can also be used for the development of the fluid handling system 301 and can also be obtained in a test setup rather than a fully functional lithographic apparatus. For example, information about the position of the meniscus 310 and / or the volume of the immersion liquid in the immersion space 11 can indicate an abnormal condition if the position or volume changes beyond an acceptable limit.

[0172] As Figure 10 depicted, transducers 702, 703, such as acoustic transducers, can be provided to transmit acoustic signals into the immersion liquid in the channel 308 and receive a return signal that is converted into an electrical signal. Although two transducers 702, 703 are shown, it may also be possible to use one transducer to transmit and receive acoustic signals. In other arrangements, more than two transducers 702, 703 can be used, for example spaced around the circumference of the fluid handling system 301. In the case where the fluid handling system 301 has a corner shape, one transducer or a pair of transducers can be located at each corner.

[0173] The transducers 702 and 703 can be used to obtain position information of the meniscus 310 by time-of-flight measurement. The transducer 702 emits an acoustic pulse. Since the meniscus 310 represents a change in acoustic impedance between the immersion liquid and the surrounding gas, a portion of the acoustic energy will be reflected as a pulse echo. The pulse echo can be detected by the transducer 703. A timer measures the time interval between the emission of the acoustic pulse and the detection of the pulse echo. It is to be understood that if the meniscus 310 is at the position indicated by 310’, the acoustic pulse and the pulse echo will travel further than when the meniscus 310 is at the position indicated by 310, and thus information about the position of the meniscus 310 can be obtained from the time-of-flight measurement.

[0174] Transducers 702 and 703 can also be used to obtain position information of the meniscus 310 by determining the resonance frequency of the immersion liquid using a signal analyzer. It is understood that a larger volume of immersion liquid typically has a lower resonance frequency. Of course, a combination of time-of-flight and frequency analysis can be used. Doppler techniques can be used to obtain information about the velocity of movement of the meniscus 310 relative to the transducers 702, 703.

[0175] The transducers 702, 703 used in the present invention can be, for example, capacitive ultrasonic transducers or piezoelectric ultrasonic transducers. An impedance matching layer can be provided between the transducer and the immersion liquid.

[0176] The above-described diagnostic tool can also be used in another device 3000, which acts as the droplet removal system (or droplet trap) described above in Figure 2c . Bubble detection in the droplet trap may not be necessary, but the diagnostic tool is very useful for monitoring the correct operation of the droplet trap.

[0177] 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 source SO, an illumination system IL, a projection system PS, a substrate support WT, etc.

[0178] Specifically, the lithographic apparatus can include a projection system PS configured to project a radiation beam B onto a region of the surface of a substrate W. The lithographic apparatus can also include Figures 3a to 5 the fluid handling systems 301, 301' described in any of the above embodiments and variations in

[0179] The lithographic apparatus can include an actuator (not shown) configured to move the substrate W relative to the fluid handling systems 301, 301'. Thus, the actuator can be used to control the position of the substrate W (alternatively, the position of the fluid handling systems 301, 301'). The actuator can be or can include a substrate support (e.g., a substrate table) WT and / or a substrate holder configured to hold the substrate W and / or a second positioner PW configured to accurately position the substrate support WT.

[0180] Although the use of the lithographic apparatus in IC manufacturing may be specifically mentioned herein, it should be understood that the lithographic apparatus described herein can have other applications. Possible other 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.

[0181] Embodiments of the invention may be implemented, where context permits, 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. The machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine, such as a computing device. For example, the 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 (such as carrier waves, infrared signals, digital signals, etc.) and others. Further, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be understood that such description is merely for convenience, and such actions are in fact caused by a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., and doing so enables the actuator or other device to interact with the physical world.

[0182] Although embodiments of the invention may be specifically mentioned herein in the context of a lithographic apparatus, embodiments of the invention may 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). These devices may generally be referred to as lithographic tools. Such lithographic tools may operate in a vacuum (non-vacuum) condition.

[0183] Although the use of embodiments of the invention in the context of optical lithography may have been specifically mentioned above, it is to be understood that the invention is not limited to optical lithography, where context permits.

[0184] Embodiments include the following numbered clauses:

[0185] 1. A fluid handling system, comprising:

[0186] A liquid confinement structure configured to confine an immersion liquid to a space between at least a portion of the liquid confinement structure and a surface of a substrate, the liquid confinement structure having apertures formed therein for passage of a radiation beam to irradiate the surface of the substrate through the immersion liquid; and

[0187] A diagnostic tool configured to detect an abnormal condition in the fluid handling system, the diagnostic tool including an acoustic system configured to measure an acoustic characteristic of the liquid confinement structure and / or the immersion liquid,

[0188] wherein the acoustic system includes a transducer configured to transmit an acoustic probe signal into the immersion liquid and / or receive acoustic waves from the immersion liquid.

[0189] 2. The fluid handling system according to item 1, wherein the diagnostic tool is configured to detect foreign objects as abnormal conditions.

[0190] 3. The fluid handling system according to item 2, wherein the diagnostic tool is configured to detect bubbles as foreign objects.

[0191] 4. The fluid handling system according to item 2 or 3, wherein the diagnostic tool is configured to detect solid contaminants (such as particles or fibers) as foreign objects.

[0192] 5. The fluid handling system according to any one of the preceding items, wherein the transducer comprises a piezoelectric transducer, desirably coupled to a diaphragm for contacting the immersion liquid.

[0193] 6. The fluid handling system according to any one of the preceding items, wherein the acoustic system is configured to transmit a probing signal into the immersion liquid and receive a return signal from the immersion liquid.

[0194] 7. The fluid handling system according to item 6, further comprising a signal analyzer configured to determine the frequency content of the return signal.

[0195] 8. The fluid handling system according to item 7, wherein the signal analyzer is configured to detect the resonance frequency characteristics of bubbles in the immersion liquid.

[0196] 9. The fluid handling system according to item 7 or 8, wherein the signal analyzer is configured to detect changes in the power spectrum of the return signal.

[0197] 10. The fluid handling system according to any one of the preceding items, wherein the liquid confinement structure has a plurality of passages configured to supply immersion liquid to or extract immersion liquid from the space, and wherein the passages respectively have different characteristic resonances.

[0198] 11. The fluid handling system according to item 10, wherein the passages respectively have different lengths, different cross-sections and / or different cross-section profiles.

[0199] 12. The fluid handling system according to any one of the preceding items, comprising a plurality of transducers located in or near the passages, the plurality of transducers being configured to supply immersion liquid to or extract immersion liquid from the space.

[0200] 13. A lithographic apparatus, having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held by the substrate holder, and a fluid handling system according to any one of the preceding items.

[0201] 14. A device manufacturing method in a lithographic apparatus, the lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto a substrate held by the substrate holder, and a fluid handling system, the method comprising:

[0202] Using the fluid handling system to confine an immersion fluid to a space between at least a part of the fluid handling system and the surface of the substrate;

[0203] Emitting an acoustic detection signal into the immersion liquid;

[0204] Receiving a return signal in response to the detection signal;

[0205] Detecting an abnormal condition in the fluid handling system based on the return signal; and

[0206] Projecting a patterned radiation beam onto the substrate through the immersion fluid in the space.

[0207] 15. The method according to item 14, wherein the steps of emitting the acoustic detection signal and receiving the return signal are performed while the substrate is stationary relative to the fluid handling system.

[0208] 16. The method according to item 14, wherein the steps of emitting the acoustic detection signal and receiving the return signal are performed while the substrate is moving relative to the fluid handling system.

[0209] 17. The method according to item 14, 15 or 16, further comprising, in response to detecting an abnormal condition, changing at least one parameter of the exposure configuration, such as: the moving speed of the substrate; the acceleration of the substrate; the moving direction of the substrate; the height of the fluid handling system; or the flow rate of the immersion fluid.

[0210] 18. The method according to any one of items 14 to 17, further comprising: before the steps of emitting the acoustic detection signal and receiving the return signal, supplying additional immersion liquid such that the passage for extracting the immersion liquid from the space is flooded.

[0211] 19. The method according to any one of items 14 to 18, wherein detecting an abnormal condition includes detecting at least one of the following: bubbles in the immersion liquid; contaminants in the passage configured to supply immersion liquid to or extract immersion liquid from the space; and blockages in the micro-sieve provided in the fluid extraction path.

[0212] 20. A droplet removal system, comprising:

[0213] A liquid supply member configured to supply liquid to a space between at least a part of the droplet removal system and the surface of the substrate;

[0214] A pumping member configured to pump liquid from the space;

[0215] A diagnostic tool configured to detect an abnormal condition in a droplet removal system, the diagnostic tool including an acoustic system configured to measure acoustic characteristics of the droplet removal system and / or a liquid, wherein the acoustic system includes a transducer configured to transmit an acoustic detection signal into the liquid and / or receive acoustic waves from the liquid.

[0216] While specific embodiments of the invention have been described above, it is to be understood that the invention may be practiced in other ways different from those described. The foregoing description is intended to be illustrative, not restrictive. Thus, it will be apparent to those skilled in the art that the described invention may be modified without departing from the scope of the claims set forth below.

Claims

1. A fluid handling system, comprising: A liquid confinement structure configured to confine an immersion liquid to a space between at least a portion of the liquid confinement structure and a surface of a substrate, the liquid confinement structure having apertures formed therein for passage of a radiation beam to irradiate the surface of the substrate by passing through the immersion liquid; And A diagnostic tool configured to detect a condition in the fluid handling system, the diagnostic tool including an acoustic system configured to measure an acoustic property of the liquid confinement structure and / or the immersion liquid, Wherein the acoustic system includes a transducer configured to emit acoustic waves into and / or receive acoustic waves from the immersion liquid.

2. The fluid handling system according to claim 1, wherein the condition is an abnormal condition, desirably wherein the diagnostic tool is configured to detect a foreign object as the abnormal condition, desirably wherein the diagnostic tool is configured to detect a bubble as the foreign object, desirably wherein the diagnostic tool is configured to detect a solid contaminant (such as a particle or a fiber) as the foreign object.

3. The fluid handling system according to claim 1 or 2, wherein the condition in the fluid handling system includes a volume of the immersion liquid and / or a position of a meniscus of the immersion liquid relative to the liquid confinement structure, and / or wherein the transducer includes a piezoelectric transducer, desirably coupled to a diaphragm for contacting the immersion liquid, and / or wherein the acoustic system is configured to emit a probe signal into the immersion liquid and receive a return signal from the immersion liquid.

4. The fluid processing system according to claim 3, wherein the acoustic system comprises: A transducer configured to emit and / or receive acoustic pulses, and a timer configured to determine a transmission time of a pulse echo, or wherein the acoustic system includes: a signal analyzer configured to determine a resonance frequency of the immersion liquid.

5. The fluid handling system according to claim 3 or 4, further comprising a signal analyzer configured to determine a frequency content of the return signal.

6. The fluid handling system according to claim 5, wherein the signal analyzer is configured to detect a resonance frequency characteristic of bubbles in the immersion liquid, and / or wherein the signal analyzer is configured to detect a change in the power spectrum of the return signal.

7. The fluid handling system according to any one of the preceding claims, wherein the liquid confinement structure has a plurality of passages configured to supply immersion liquid to or withdraw immersion liquid from the space, and wherein the passages respectively have different characteristic resonances, and / or include a plurality of transducers located in or near the passages, the plurality of transducers being configured to supply immersion liquid to or withdraw immersion liquid from the space.

8. The fluid handling system according to claim 7, wherein the passages respectively have different lengths, different cross-sections and / or different cross-section profiles.

9. A lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held by the substrate holder, and a fluid handling system according to any one of the preceding claims.

10. A device manufacturing method in a lithographic apparatus, the lithographic apparatus having a substrate holder configured to hold a substrate, a projection system configured to project a radiation beam onto the substrate held by the substrate holder, and a fluid handling system, the method comprising: Using the fluid handling system to confine an immersion fluid to a space between at least a part of the fluid handling system and the surface of the substrate; Emitting an acoustic detection signal into the immersion liquid; Receiving a return signal in response to the detection signal; Detecting a condition in the fluid handling system based on the return signal; And Projecting a patterned radiation beam onto the substrate through the immersion fluid in the space.

11. The method according to claim 10, wherein the condition is an abnormal condition, desirably wherein the steps of emitting the acoustic detection signal and receiving the return signal are performed while the substrate is stationary relative to the fluid handling system, desirably wherein the steps of emitting the acoustic detection signal and receiving the return signal are performed while the substrate is moving relative to the fluid handling system.

12. The method according to claim 10 or 11, further comprising: In response to detecting an abnormal condition, changing at least one parameter of the exposure configuration, such as: the moving speed of the substrate; The acceleration of the substrate; The moving direction of the substrate; the height of the fluid handling system; or the flow rate of the immersion fluid, and / or further comprising: before the steps of emitting the acoustic detection signal and receiving the return signal, supplying additional immersion liquid such that the passage for extracting the immersion liquid from the space is flooded.

13. The method according to any one of claims 10 to 12, wherein detecting the abnormal condition comprises: Detecting at least one of the following: bubbles in the immersion liquid; Contaminants in the passage configured to supply the immersion liquid to the space or extract the immersion liquid from the space; And blockages in the micro-sieve provided in the fluid extraction path, and / or wherein the condition in the fluid handling system includes: the volume of the immersion liquid and / or the position of the meniscus of the immersion liquid relative to the liquid confinement structure.

14. A droplet removal system, comprising: A liquid supply member configured to supply liquid to a space between at least a part of the droplet removal system and the surface of a substrate; An extraction member configured to extract the liquid from the space; A diagnostic tool configured to detect a condition in the droplet removal system, the diagnostic tool including an acoustic system configured to measure the acoustic characteristics of the droplet removal system and / or the liquid, Wherein the acoustic system includes a transducer configured to emit acoustic waves into the liquid and / or receive acoustic waves from the liquid.

15. The droplet removal system according to claim 14, wherein the condition is an abnormal condition, and / or wherein the condition in the fluid handling system includes the volume of the immersion liquid and / or the position of the meniscus of the immersion liquid relative to the liquid confinement structure.

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