Substrate support and lithographic apparatus

Abstract

A substrate support configured to support a substrate in a lithographic apparatus, the substrate support comprising: a first circumferential wall; a first opening radially outward of the first circumferential wall and configured to supply and / or extract gas; a second circumferential wall radially outward of the first opening; a second opening in fluid communication with ambient pressure and radially outward of the second circumferential wall; a third circumferential wall radially outward of the second opening; a third opening radially outward of the third circumferential wall and configured to draw fluid; and a fourth circumferential wall radially outward of the third opening.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 22179329.2, filed on June 15, 2022, and incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a substrate support configured to support a substrate in a lithographic device, a method of loading a substrate onto a substrate support, a lithographic device comprising a substrate support, and a method of manufacturing a device, the method comprising loading a substrate onto a substrate support. Background Art

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

[0005] As semiconductor manufacturing processes continue to evolve, following a trend generally known as 'Moore's Law', the size of circuit elements has been continuously reduced, but the number of functional elements (such as transistors) per device has steadily increased for decades. In order to keep up with Moore's Law, the semiconductor industry is looking for technologies that can create smaller and smaller features. To project a pattern onto a substrate, a lithography device 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 improvements in resolution of smaller features can be achieved by providing an immersion fluid with a relatively high refractive index, such as water, on the substrate during exposure. The effect of the immersion fluid is to enable imaging of smaller features, since the wavelength of the exposure radiation is shorter in the fluid than in the gas. The effect of the immersion fluid can also be viewed as increasing the effective numerical aperture (NA) of the system, and also increasing the depth of focus.

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

[0008] In the semiconductor manufacturing process, the substrate is supported on a substrate support, and in particular, the substrate is supported on a plurality of protrusions protruding from the surface of the substrate support.

[0009] In the semiconductor industry, there is a growing trend to integrate more functionality onto a substrate surface by shrinking and increasing the number of stacked film layers on the substrate. Increasing the number of layers stacked on the substrate increases the stress generated between the film and the substrate, which can cause severe substrate warping.

[0010] This can result in variable friction between the outer circumferential ring of the burls and the underside of the substrate, resulting in high reproducibility of the substrate. This can be mitigated by surrounding the outer circumferential ring of the burls with a fluid (i.e., immersion fluid). However, this results in higher humidity gradients, resulting in flatness drift of the substrate support.

[0011] It is an object of the present invention to alleviate the problems associated with loads that warp the substrate without increasing the flatness drift of the substrate support.

[0012] According to the present invention, there is provided a substrate support configured to support a substrate in a lithographic apparatus, comprising:

[0013] a first circumferential wall;

[0014] a first opening, radially outside the first circumferential wall and configured to supply and / or extract gas;

[0015] a second circumferential wall, radially outward of the first opening;

[0016] a second opening in fluid communication with ambient pressure and radially outward of the second circumferential wall;

[0017] a third circumferential wall, radially outward of the second opening;

[0018] a third opening radially outward of the third circumferential wall and configured to extract fluid; and

[0019] The fourth circumferential wall is located radially outside the third opening.

[0020] According to the present invention, there is also provided a method for loading a substrate onto a substrate support, the substrate support having a first circumferential wall, a second circumferential wall radially outside the first circumferential wall, a third circumferential wall radially outside the second circumferential wall, and a fourth circumferential wall radially outside the third circumferential wall, wherein a first region is between the first circumferential wall and the second circumferential wall, a second region is between the second circumferential wall and the third circumferential wall, and the method comprises:

[0021] a substrate loading step in which a gas is supplied to the first region;

[0022] A substrate clamping step wherein a gas is drawn from the first region and a fluid is drawn from the third region.

[0023] According to the present invention, there is also provided a lithographic apparatus comprising a substrate support.

[0024] According to the present invention, there is also provided a method of manufacturing a device, comprising loading a substrate onto a substrate support.

[0025] Further embodiments, features, and advantages of the present invention, as well as the structure and operation of the various embodiments, features, and advantages of the present invention are described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which corresponding reference characters indicate corresponding parts, and in which:

[0027] Figure 1 depicts a schematic overview of a lithography apparatus;

[0028] Figure 2 and 3 depicted in cross-section are two different versions of a fluid handling system for use in a lithographic projection apparatus;

[0029] Figure 4 A substrate support not according to the invention is depicted in cross section.

[0030] Figure 5 A portion of a substrate support not according to the invention (comparative example) is depicted in cross section in a loaded state.

[0031] Figure 6 A portion of a substrate support not according to the invention (comparative example) is depicted in cross section in a clamped state.

[0032] Figure 7 A portion of a substrate support according to the invention is depicted in cross section in a loaded state.

[0033] Figure 8 A portion of a substrate support according to the invention is depicted in cross section in a clamped state.

[0034] Fig. 9 A portion of a substrate support according to the invention is depicted in cross section in a bypass state.

[0035] Fig.10 A portion of a substrate support according to the invention is depicted in cross section in a clamped state.

[0036] Fig.11AMultifunctional channels and multifunctional passages that may be included in a substrate support according to the present invention are depicted.

[0037] Fig. 11B Multifunctional channels and multifunctional passages that may be included in a substrate support according to the present invention are depicted.

[0038] Fig.12 Plots of the moment about the horizontal axis (M) versus the tilt angle (θ) for a single multifunctional channel and three multifunctional channels at several flow rates are depicted.

[0039] The features shown in the drawings are not necessarily drawn to scale, and the sizes and / or arrangements depicted are not limiting. It is to be understood that the drawings include optional features that may not be essential to the present invention. In addition, not all features of the device are depicted in every figure in the drawings, and the drawings may only show some of the components relevant to describing a particular feature. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present disclosure.

[0041] The measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, a variety of substitutions and modifications may be made by those skilled in the art, all of which should fall within the scope of the present disclosure. In this document, the terms "radiation" and "beam" are used to cover all types of electromagnetic radiation, including ultraviolet radiation (e.g., wavelengths of 365, 248, 193, 157 or 126 nm).

[0042] The terms "reticle", "mask" or "patterning device" as used herein may be broadly interpreted as referring to a general patterning device that can be used to impart a patterned cross-section to an incoming radiation beam, corresponding to the pattern to be created in a target portion of the substrate. In this context, the term "light valve" may also be used. In addition to classical masks (transmissive or reflective, binary, phase-shifting, hybrid, etc.), other examples of such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0043] Figure 1A lithographic apparatus is schematically depicted. The lithographic apparatus comprises an illumination system (also referred to as illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or DUV radiation), a mask support (e.g. mask table) MT configured to support a patterning device (e.g. mask) MA and connected to a first positioner PM (configured to accurately position the patterning device MA according to certain parameters), a substrate support (e.g. wafer stage) WT configured to hold a substrate (e.g. resist coated wafer) W and connected to a second positioner PW (configured to accurately position the substrate support WT according to certain parameters), and a projection system (e.g. refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W.

[0044] In operation, the illumination system IL receives a radiation beam B from a radiation source SO (e.g., via a beam delivery system BD). The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic and / or other types of optical components, or any combination thereof, for directing, shaping and / or controlling the radiation. The illuminator IL may be used to condition the radiation beam B so as to have a desired spatial and angular intensity distribution in its cross-section at the plane of the patterning device MA.

[0045] The term "projection system" PS as used herein should be broadly interpreted as covering various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optical systems or any combination thereof, as appropriate with respect to the exposure radiation used and / or other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" PS.

[0046] The lithographic apparatus is of a type in which at least a portion of the substrate W may be covered by an immersion liquid having a relatively high refractive index, such as water, to fill an immersion space between the projection system PS and the substrate W, which is also known as immersion lithography. More information on immersion technology is given in US 6,952,253, which is incorporated herein by reference.

[0047] The lithographic apparatus may be of a type having two or more substrate supports WT (also referred to as a "dual stage"). In such a "multi-stage" machine, the substrate supports WT may be used in parallel, and / or steps for preparing a substrate W for subsequent exposure may be performed on a substrate W located on one of the substrate supports WT, while another substrate W on another substrate support WT is used to expose a pattern on another substrate W.

[0048] In addition to the substrate support WT, the lithographic apparatus may comprise a measurement platform (not depicted in the drawings). The measurement platform is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure properties of the projection system PS or properties of the radiation beam B. The measurement platform may hold a plurality of sensors. The cleaning device may be arranged to clean a part of the lithographic apparatus, e.g. a part of the projection system PS or a part of a system for providing immersion liquid. The measurement platform may be moved under the projection system PS when the substrate support WT is away from the projection system PS.

[0049] In operation, a radiation beam B is incident on a patterning device (e.g. a mask) MA and is patterned by a pattern (design layout) present on the patterning device MA, which is held on a mask support MT. After traversing the mask MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of a substrate W. With the aid 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 focused and aligned positions. Similarly, the first positioner PM and possibly another position sensor (not shown) are also provided. Figure 1 The patterning device MA (depicted explicitly in FIG. 1 ) can be used to accurately position the patterning device MA relative to the path of the radiation beam B. The patterning device MA and the substrate W can be aligned using the mask alignment marks M1, M2 and the substrate alignment marks P1, P2. Although the illustrated substrate alignment marks P1, P2 occupy dedicated target portions, they can be located in the space between target portions. When the substrate alignment marks P1, P2 are located between target portions C, these are referred to as scribe line alignment marks.

[0050] In order to illustrate the present invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes, i.e., an x-axis, a y-axis, and a z-axis. Each of the three axes is orthogonal to the other two axes. The rotation around the x-axis is called an Rx rotation. The rotation around the y-axis is called an Ry rotation. The rotation around 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 and is only used to illustrate. On the contrary, another coordinate system such as a cylindrical coordinate system can be used to illustrate the present invention. The orientation of the Cartesian coordinate system can be different, for example, so that the z-axis has a component along the horizontal plane.

[0051] Immersion technology has been introduced into lithography systems 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 inserted into an immersion space 11 between the apparatus's projection system PS (through which a patterned beam is projected toward the substrate W) and the substrate W. The immersion liquid covers at least a portion of the substrate W beneath the final element of the projection system PS. Thus, at least the portion of the substrate W that undergoes exposure is immersed in the immersion liquid.

[0052] In commercial immersion lithography, the immersion liquid body is water. Typically, the water is high purity distilled water, such as ultrapure water (UPW) commonly used in semiconductor manufacturing plants. In an immersion system, the UPW is typically purified, and it may undergo additional treatment steps before being supplied to the immersion space 11 as an immersion liquid. In addition to water as an immersion liquid, other liquids with a high refractive index may also be used, for example: hydrocarbons, such as fluorinated hydrocarbons; and / or aqueous solutions. Further, in addition to liquids, other fluids are also envisioned for use in immersion lithography.

[0053] In this specification, reference will be made in the description to local immersion, wherein the immersion liquid is confined, in use, to an immersion space 11 between a final element and a surface facing the final element. The facing surface is the surface of the substrate W or the surface of the support platform (or substrate support WT) which is coplanar with the surface of the substrate W. (Note that, unless expressly stated otherwise, references to the surface of the substrate W hereinafter also refer in addition to or as an alternative to the surface of the substrate support WT; and vice versa). A fluid handling structure IH present between the projection system PS and the substrate support WT is used to confine the immersion liquid to the immersion space 11. The immersion space 11 filled with immersion liquid is smaller in plane than the top surface of the substrate W, and the immersion space 11 remains substantially stationary relative to the projection system PS, while the substrate W and the substrate support WT move underneath.

[0054] Other immersion systems have been envisaged, such as unconfined immersion systems (so-called 'all wet' immersion systems) and bath systems. In an unconfined immersion system, the immersion liquid covers an area larger than the surface under the final element. The liquid outside the immersion space 11 is present as a thin liquid film. The liquid may cover the entire surface of the substrate W, or even the substrate W and a substrate support WT coplanar with the substrate W. In a bath system, the substrate W is completely immersed in a bath of immersion liquid.

[0055] The fluid handling structure IH is a structure that supplies immersion liquid to the immersion space 11, removes immersion liquid from the immersion space 11 and thereby confines immersion liquid to the immersion space 11. The fluid handling structure IH includes features that are 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 conduits that supply or withdraw immersion liquid from the immersion space 11 and whose operation depends on relative movement of the platform below the projection system PS. In more recent designs, the fluid handling structure extends along at least a portion of the boundary of the immersion space 11 between the final element of the projection system PS and the substrate support WT or substrate W, thereby partially defining the immersion space 11.

[0056] The fluid handling structure IH may have a selection of different functions. Each function may be derived from a corresponding feature that enables the fluid handling structure IH to achieve that function. The fluid handling structure IH may be referred to by many different terms, each of which refers to a function, such as a barrier member, a sealing member, a fluid supply system, a fluid removal system, a liquid confinement structure, etc.

[0057] As a barrier member, the fluid handling structure IH is a barrier to the flow of immersion liquid from the immersion space 11. As a liquid confinement structure, the structure confines the immersion liquid to the immersion space 11. As a sealing member, the sealing features of the fluid handling structure IH form a seal to confine the immersion liquid to the immersion space 11. The sealing features may include additional air flow from an opening in the surface of the sealing member, such as an air knife.

[0058] The fluid handling structure IH may supply immersion fluid and is therefore a fluid supply system.

[0059] The fluid handling structure IH may at least partially confine immersion fluid and thus be a fluid confinement system.

[0060] The fluid handling structure IH may provide a barrier to the immersion fluid and therefore be a barrier member, such as a fluid confinement structure.

[0061] The fluid handling structure IH may generate or use a gas flow, for example to help control the flow and / or position of the immersion fluid.

[0062] The gas flow may form a seal to confine the immersion fluid and thus the fluid handling structure IH may be referred to as a sealing member; such a sealing member may be a fluid confinement structure.

[0063] An immersion liquid may be used as the immersion fluid. In this case, the fluid handling structure IH may be a liquid handling system. With reference to the above description, references in this paragraph to features defined relative to a fluid may be understood to include features defined relative to a liquid.

[0064] The lithographic apparatus has a projection system PS. During exposure of the substrate W, the projection system PS projects a patterned radiation beam onto the substrate W. In order to reach the substrate W, the path of the radiation beam B from the projection system PS passes through an immersion liquid confined by a fluid handling structure IH between the projection system PS and the substrate W. The projection system PS has a lens element in contact with the immersion liquid, i.e. the last one in the beam path. This lens element in contact with the immersion liquid may be referred to as the 'last lens element' or the 'final element'. The final element is at least partially surrounded by the fluid handling structure IH. The fluid handling structure IH may confine the immersion liquid to below the final element and above the facing surface.

[0065] like Figure 1 As depicted, the lithographic apparatus comprises a controller 500. The controller 500 is configured to control a substrate table WT.

[0066] Figure 2 A local liquid supply system or fluid handling system is schematically depicted. The liquid supply system is provided with a fluid handling structure IH (or liquid confinement structure) which extends along at least a portion of the boundary of the space 11 between the final element of the projection system PS and the support table WT or substrate W. The fluid handling structure IH is substantially stationary relative to the projection system PS in the XY plane, although there may be some relative movement in the Z direction (direction of the optical axis). In examples, a seal is formed between the surface of the fluid handling structure IH and the substrate W, and may be a contactless seal, such as an airtight seal (such a system with an airtight seal is disclosed in EP1,420,298) or a liquidtight seal.

[0067] The fluid handling structure IH at least partially confines immersion liquid to a space 11 between the final element of the projection system PS and the substrate W. The space 11 is at least partially formed by the fluid handling structure IH being positioned below and surrounding the final element of the projection system PS. Immersion liquid enters the space 11 below the projection system PS and within the fluid handling structure IH through one of the liquid openings 13. Immersion liquid may be removed through another of the liquid openings 13. Immersion liquid may enter the space 11 through at least two liquid openings 13. Which liquid opening 13 is used for supplying immersion liquid and optionally for removing immersion liquid may depend on the direction of movement of the support table WT.

[0068] The immersion liquid can be confined to the space 11 by a contactless seal, such as a gas seal 16 formed by a gas, which is formed between the bottom of the fluid handling structure IH and the surface of the substrate W during use. The gas in the gas seal 16 is provided to the gap between the fluid handling structure IH and the substrate W via the inlet 15 under pressure. The gas is extracted via the outlet 14. The overpressure on the gas inlet 15, the vacuum on the outlet 14 and the geometry of the gap are arranged so that there is an inward high-speed gas flow, thereby confining the immersion liquid. Such a system is disclosed in US 2004 / 0207824, which is incorporated herein by reference in its entirety. In the example, the fluid handling structure IH does not have a gas seal 16.

[0069] Figure 3 is a side cross-sectional view depicting yet another liquid supply system or fluid handling system. Figure 3 The arrangement illustrated and described below can be applied to the above-described and Figure 1 The liquid supply system is provided with a fluid handling structure IH (or liquid confinement structure) which extends along at least a part of a boundary of a space 11 between the final element of the projection system PS and the support table WT or substrate W.

[0070] The fluid handling structure IH at least partially confines the immersion liquid to a space 11 between the final element of the projection system PS and the substrate W. The space 11 is at least partially formed by the fluid handling structure IH positioned below and surrounding the final element of the projection system PS. In the example, the fluid handling structure IH comprises a main body member 53 and a porous member 33. The porous member 33 is plate-shaped and has a plurality of holes (i.e., openings or pores). The porous member 33 may be a mesh plate in which a number of small holes 84 are formed in the mesh. Such a system is disclosed in US 2010 / 0045949 A1, which is incorporated herein by reference in its entirety.

[0071] The main body member 53 includes a supply port 72 capable of supplying immersion liquid to the space 11 and a recovery port 73 capable of recovering immersion liquid from the space 11. The supply port 72 is connected to a liquid supply device 75 via a passage 74. The liquid supply device 75 is capable of supplying immersion liquid to the supply port 72 through the corresponding passage 74. The recovery port 73 is capable of recovering immersion liquid from the space 11. The recovery port 73 is connected to a liquid recovery device 80 via a passage 79. The liquid recovery device 80 recovers the immersion liquid recovered via the recovery port 73 through the passage 29. The porous member 33 is disposed in the recovery port 73. The liquid supply operation is performed using the supply port 72 and the liquid recovery operation is performed using the porous member 33, and the space 11 is formed between the projection system PS and the fluid handling structure IH on one side and the substrate W on the other side.

[0072] Figure 4 A portion of a lithographic apparatus which is not in accordance with the present invention but which may be used to illustrate features of the present invention is shown. Figure 4 The arrangement illustrated and described below can be applied to the above-described and Figure 1 A lithographic apparatus is shown. Figure 4 is a cross section through the substrate support 20 and the substrate W. In an embodiment, the substrate support 20 comprises one or more conditioning channels 61 of a thermal regulator 60, which will be described in more detail below. There is a gap 5 between the edge of the substrate W and the edge of the substrate support 20. When the edge of the substrate W is imaged or at other times, such as when the substrate W is first moved under the projection system PS (as described above), the immersion space 11 filled with liquid by the fluid handling structure IH (for example) will at least partially pass through the gap 5 between the edge of the substrate W and the edge of the substrate support 20. This may cause liquid to enter the gap 5 from the immersion space 11.

[0073] The substrate W is held by a support 21 (e.g., a raised spot or a burl platform) comprising one or more burls 41 (i.e., protruding from the surface). The support 21 is an example of an object holder. Another example of an object holder is a mask holder. The negative pressure applied between the substrate W and the substrate support 20 helps to ensure that the substrate W is firmly held in place. However, if immersion liquid enters between the substrate W and the support 21, this may cause difficulties, particularly when unloading the substrate W.

[0074] In order to handle immersion liquid entering the gap 5, at least one drainage feature 10, 12 is provided at the edge of the substrate W to remove immersion liquid entering the gap 5. Figure 4 In the embodiment of the present invention, two drainage members 10, 12 are shown, although there may be only one drainage member, or there may be more than two drainage members. In an embodiment, each of the drainage members 10, 12 is annular so that the entire periphery of the substrate W is surrounded.

[0075] The main function of the first drainage member 10 (located radially outward of the edge of the substrate W / support 21) is to help prevent gas bubbles from entering the immersion space 11 of the liquid confinement structure IH where the liquid is present. Such bubbles may adversely affect the imaging of the substrate W. The presence of the first drainage member 10 helps to avoid gas in the gap 5 from escaping into the immersion space 11 in the liquid confinement structure IH. If gas escapes into the immersion space 11, this may cause bubbles to float within the immersion space 11. If in the path of the projection beam, such bubbles may cause imaging errors. The first drainage member 10 is configured to remove gas from the gap 5 between the edge of the substrate W and the edge of the recess in the substrate support 20 where the substrate W is placed. The edge of the recess in the substrate support 20 may be defined by a cover ring 101, which is optionally separated from the support 21 of the substrate support 20. The shape of the cover ring 101 in a plane may be formed as a ring and surround the outer edge of the substrate W. The first drainage member 10 extracts most of the gas and only extracts a small amount of immersion liquid.

[0076] A second drainage feature 12 (located radially inwardly of the edge of the substrate W / support 21) is provided to help prevent liquid from entering the space below the substrate W from the gap 5, thereby preventing the substrate W from being effectively released from the substrate table WT after imaging. The provision of the second drainage feature 12 reduces or eliminates any problems that might occur due to liquid finding a way under the substrate W.

[0077] like Figure 4 As depicted, in an embodiment, the lithographic apparatus comprises a first extraction channel 102 for two-phase flow therethrough. The first extraction channel 102 is formed in a block. The first drainage member 10 and the second drainage member 12 are provided with respective openings 107, 117 and respective extraction channels 102, 113, respectively. The extraction channels 102, 113 are in fluid communication with the respective openings 107, 117 through respective passages 103, 114.

[0078] like Figure 4As depicted, the cover ring 101 has an upper surface. The upper surface extends circumferentially around the substrate W on the support body 21. In use of the lithographic apparatus, the fluid handling structure IH moves relative to the substrate support 20. During this relative movement, the fluid handling structure IH moves across the gap 5 between the cover ring 101 and the substrate W. In an embodiment, the relative movement is caused by the substrate support 20 moving under the fluid handling structure IH. In an alternative embodiment, the relative movement is caused by the fluid handling structure IH moving above the substrate support 20. In yet another alternative embodiment, the relative movement is provided by the movement of the substrate support 20 under the fluid handling structure IH and the movement of the fluid handling structure IH above the substrate support 20. In the following description, the movement of the fluid handling structure IH will be used to represent the relative movement of the fluid handling structure IH relative to the substrate support 20.

[0079] <Comparison example>

[0080] The warping of the substrate W due to the stacking of film layers generally means that the substrate W is in an "umbrella" form, where the center of the substrate W is the highest point (i.e., farthest from the substrate support WT), and radially outside the center, the substrate W bends downward. In order to alleviate the umbrella deformation during loading, gas can be blown from the substrate support WT to the underside of the substrate W in the edge region. This deforms the edge region of the substrate W upward, alleviating any umbrella deformation, and ensuring that the radially outermost ring of the burls 41 is the last contact point between the substrate W and the substrate support WT during substrate loading. Therefore, the friction variability at the outer circumferential ring of the burls 41 is reduced, which leads to high substrate loading reproducibility. This "edge lift" technique can also be used with substrates W that are not in umbrella form. For example, flat substrates W, bowl-shaped substrates W, and saddle-shaped substrates W can take advantage of this technique during substrate unloading.

[0081] An example of a substrate support WT implementing such an "edge lift" functionality is described below. This example may be used to highlight various aspects of the invention. Figure 5 and Figure 6 A portion of a substrate support 200 is shown. The portion of the substrate support 200 shown may be integrated in a Figure 4 However, parts of the substrate support 200 may also be integrated in other configurations of substrate supports.

[0082] The substrate support 200 includes a support body 221. The support body 221 includes a plurality of burls 241. When a substrate W is supported by the support body 221, the substrate W is in direct contact with the support body 221. The support body 221 is a part of the substrate support 200 that physically supports the lower side of the substrate W. The distal ends of the burls 241 form a plane that supports the lower side of the substrate W. The lower side of the substrate W is in contact with the distal ends of the burls 241. The burls 241 are located on the upper side of the support body 221.

[0083] like Figure 5 and 6 As shown, the substrate support 200 also includes a plurality of seals 231, 232, 233. The seals 231, 232, 233 are circumferential rings protruding from the substrate support 200. In this example, there are at least three seals: an inner seal 231, an intermediate seal 232 located radially outward of the inner seal 231; and an outer seal 233 located radially outward of the intermediate seal 232.

[0084] The plurality of seals 231, 232, 233 define a plurality of regions 251, 252 between the substrate support 200 and the substrate W. The multi-function liquid gutter 251 is a region extending around the circumference of the substrate support 200 between the inner seal 231 and the middle seal 232. The fluid extraction liquid gutter 252 is a region extending around the circumference of the substrate support 200 between the middle seal 232 and the outer seal 233.

[0085] like Figure 5 and 6 As shown, the substrate support 200 further includes a plurality of openings 261, 262. In an embodiment, the support body 221 includes a multifunctional opening 261 (in the multifunctional liquid draw groove 251) located between the inner seal 231 and the middle seal 232 and a fluid extraction opening 262 (in the fluid extraction liquid draw groove 252) located between the middle seal 230 and the outer seal 233.

[0086] The multifunctional opening 261 may be configured to supply gas to and extract gas from the multifunctional liquid extraction groove 252 , and the fluid extraction opening 262 may be configured to extract fluid from the fluid extraction groove 252 .

[0087] The area located radially inward of the inner seal 231 is the clamping area 253. In an embodiment, the substrate support 200 may further include a clamping opening 263 located radially inward of the inner seal 231 (in the clamping area 253), the clamping opening 263 being configured to extract gas from the clamping area 253. When a substrate W is loaded onto the substrate support 200, the substrate W is first received by a plurality of e-pins (not shown) in an extended position. The e-pins are then retracted so that the substrate W is lowered toward the substrate support 200. When the underside of the substrate W contacts the plurality of burls 241, the e-pins continue to retract so that the substrate W is no longer in contact with the e-pins, and the substrate W is fully supported by the plurality of burls 241.

[0088] In this "loading state" ( Figure 5 ), gas is supplied to the multifunctional liquid introduction groove 251 by the multifunctional opening 261, so that the pressure in the multifunctional liquid introduction groove 251 increases. Therefore, the pressure in the multifunctional liquid introduction groove 251 becomes greater than the ambient pressure, and a force is applied to the lower side of the substrate W in an upward direction (i.e., in a direction away from the substrate support 200). The upward force deforms the edge of the substrate W upward. This may cause the umbrella-shaped deformation to be reduced or completely eliminated. The upward force may even reverse the direction of the substrate deformation, causing the edge of the substrate W to bend upward (i.e., form a bowl shape).

[0089] During the loading phase, gas can be extracted from the clamping area 253 through the clamping opening 263, so that a negative pressure (a pressure less than the ambient pressure) is established in the clamping area 253, and a force is applied to the underside of the substrate W in the direction towards the substrate support 200, so that the substrate W is clamped to the substrate support 200.

[0090] During the loading phase, the fluid extraction opening 262 may be closed. This means that the fluid extraction opening 262 does not extract fluid.

[0091] Figure 6 A subsequent "clamped state" is depicted. In the clamped state, immersion fluid that flows through the gap 5 between the substrate W and the cover ring 201 also passes through the outer seal 233 and is present in the fluid extraction gutter 252. It is this immersion fluid that is extracted by the fluid extraction opening 262. Further, in the clamped state, pressure continues to be supplied to the multi-function gutter 251 through the multi-function opening 261 so that the immersion fluid does not exceed the middle seal 232. The pressure supplied to the multi-function gutter 251 during this clamped state may be ambient pressure.

[0092] In this clamped state, the multi-function opening 261 continues to supply gas to the multi-function liquid introduction groove 251 to prevent the immersion fluid from passing over the intermediate seal 232.

[0093] There are many disadvantages to this configuration. First, it is not possible to have an arrangement that meets both the edge lift requirement and the flatness requirement. In order for the edge lift force to produce the required edge lift deformation, the distance between the inner seal 231 and the middle seal 232 must be increased. However, in order to avoid a flatness ridge during the clamping state, the distance between the inner seal 231 and the middle seal 232 must be reduced. Unless otherwise specified, the distance between the seals (or the distance between the circumferential walls in the claims) refers to the distance between the opposing faces of the seals. For example, the distance between the inner seal 231 and the middle seal 232 is the distance between the radial outer surface of the inner seal 231 and the radial inner surface of the middle seal 232.

[0094] During the clamping state, it is necessary to humidify the air entering through the multifunctional opening 261. This is because, if the humidity is too low, an excessive cold load will be applied to the substrate support 200. For example, an excessive cold load will be applied in and around the fluid extraction area 252 and the fluid extraction opening 262. This may cause transient structural deformation of the substrate support 200, which may eventually cause overlap loss. The second disadvantage of the above example is that if the humidity of the air entering the multifunctional opening 261 during the clamping state is too high, it is likely to move radially inward to the clamping area 253. If there is a humidity gradient in the clamping area 253, an electrochemical reaction occurs on the burl 241, which causes a flatness drift in the clamping area 253 of the substrate support 200. This means that when the substrate support 200 supports the substrate W, there is a drift in the flatness of the substrate W.

[0095] Further, in the above examples, uncontrolled air (eg, air containing contaminants or air whose temperature is not controlled) may flow between the substrate W and the substrate support 200 .

[0096] <Example>

[0097] Figures 7 to 10 A portion of a substrate support 300 according to the present invention is illustrated. The substrate support 300 is similar to the substrate support 200 illustrated in the comparative example, but includes an additional seal (inner-middle seal 334) and an additional opening (environmental opening 364). As with the portion of the substrate support 200 in the above comparative example, the portion of the substrate support 300 may be integrated into a structure such as the substrate support 20 described above. However, the present invention is not limited thereto, and a portion of the substrate support 300 may be integrated into a substrate support having a different configuration.

[0098] As in the comparative example, the substrate support 300 includes a support body 321. The support body 321 includes a plurality of burls 341. When a substrate W is supported by the substrate support 300, the substrate W is in direct contact with the support body 321. The support body 321 is a part of the substrate support 300 that physically supports the lower side of the substrate W. The distal ends of the burls 341 form a plane that supports the lower side of the substrate W. The lower side of the substrate W is in contact with the distal ends of the burls 341. The burls 341 are located on the upper side of the support body 321.

[0099] like Figures 7 to 10 As shown, the substrate support 300 includes a plurality of seals 331, 332, 333, 334. These seals 331, 332, 333, 334 are circumferential rings protruding from the substrate support 300. In an embodiment, there are at least four seals: an inner seal 331, an inner-middle seal 334 located radially outward of the inner seal 331; an middle seal 332 located radially outward of the inner-middle seal 334; and an outer seal 333 located radially outward of the middle seal 332. The inner seal 331 is an example of a first circumferential wall, the inner-middle seal 334 is an example of a second circumferential wall, the middle seal 332 is an example of a third circumferential wall, and the outer seal 333 is an example of a fourth circumferential wall. Figures 7 to 10 In the illustrated embodiment, the inner seal 331 , the inner-middle seal 334 , the middle seal 332 , and the outer seal 333 are circumferential rings that protrude from the surface of the support body 321 .

[0100] The plurality of seals 331, 332, 333, 334 define a plurality of regions between the substrate support 300 and the substrate W. The multi-function liquid draw groove 351 is a region extending around the circumference of the substrate support 300 between the inner seal 331 and the inner-middle seal 334. The environmental liquid draw groove 354 is a region extending around the circumference of the substrate support 300 between the inner-middle seal 334 and the middle seal 332. The fluid extraction liquid draw groove 352 is a region extending around the circumference of the substrate support 300 between the middle seal 332 and the outer seal 333.

[0101] exist Figures 7 to 10 , the support body 321 also includes a plurality of openings 361, 364, 362. These are: a multifunctional opening 361 arranged between the inner seal 331 and the inner-middle seal 334 (in the multifunctional liquid inlet groove 351); an environmental opening 364 arranged between the inner-middle seal 334 and the middle seal 332 (in the environmental liquid inlet groove 354); and a fluid extraction opening 362 arranged between the middle seal 332 and the outer seal 333 (in the fluid extraction liquid inlet groove 352). The multifunctional opening 361 is an example of a first opening, the environmental opening 364 is an example of a second opening, and the fluid extraction opening 362 is an example of a third opening.

[0102] In an embodiment, the multifunctional opening 361 is configured to supply and extract gas to the multifunctional liquid extraction groove 351. However, the multifunctional opening 361 can be configured to only supply gas. The ambient opening 364 can be configured to communicate with the ambient pressure fluid. The ambient pressure can be provided from the atmosphere or a fluid source within the system. The ambient opening 364 can also be configured to communicate with a positive pressure fluid (a pressure greater than the ambient pressure). The fluid extraction opening 362 is configured to extract fluid from the fluid extraction liquid extraction groove 352. The fluid extraction opening 362 is Figure 4 Depicted is an example of a second opening 117 in a substrate support 20. As with the second opening 117 in the substrate support 20, the fluid extraction opening 362 may be part of a drainage component system, such as the second drainage component 12 in the substrate support 2, which has a plurality of channels and passages configured to contain fluids.

[0103] As in the comparative example, the area radially inside the inner seal 331 is the clamping area 353. In an embodiment, the support body 321 may further include a clamping opening 363 radially inside the inner seal 331 (in the clamping area 353) configured to extract gas from the clamping area 353.

[0104] As in the comparative example, when a substrate W is loaded onto the substrate support 300, the substrate W is first received by the plurality of e-pins (not shown) in their extended positions. The e-pins are then retracted so that the substrate W is lowered toward the substrate support 300. When the lower side of the substrate W contacts the plurality of burls 341, the e-pins continue to be retracted so that the substrate W is no longer in contact with the e-pins and the substrate W is fully supported by the plurality of burls 341.

[0105] In this "loading state" ( Figure 7 ), gas is supplied from the multifunctional opening 361 to the multifunctional liquid introduction groove 351, so that the pressure in the multifunctional liquid introduction groove 351 increases. Therefore, the pressure in the multifunctional liquid introduction groove 351 becomes greater than the ambient pressure. Because the pressure in the multifunctional liquid introduction groove 351 is greater than the pressure above the substrate W, a force is applied to the substrate W in an upward direction (i.e., in a direction away from the substrate support 300).

[0106] The substrate support 300 is configured so that the multifunctional liquid guide groove 351 is located near the edge of the substrate W. Therefore, the upward force applied to the substrate W is applied to the edge region of the substrate W. In a substrate W with a diameter of 300 mm, the edge region may be a region where the distance to the center of the substrate W (i.e., the radial distance) is greater than 135 mm. Typically, the edge region may be a region where the distance to the center of the substrate W is greater than 45% of the diameter of the substrate W. Applying an upward force in this region causes the edge of the substrate W to deform upward. This ensures that during substrate W loading, the radially outermost circumferential ring of the burls 342 is the last contact point between the substrate support 300 and the substrate W, which may not otherwise be the case when an "umbrella" shaped substrate W is loaded onto the substrate support 300. This reduces the friction variability between the radially outermost circumferential ring of the burls 342 and the underside of the substrate W, thereby reducing substrate W loading reproducibility.

[0107] During the loading phase, the ambient opening 364 and the fluid extraction opening 362 may be closed. This means that the ambient opening 364 is not in fluid communication with ambient pressure and the fluid extraction opening 362 is not extracting fluid.

[0108] In the method of the present invention, gas is extracted from the clamping opening 363 during the loading phase, so that a negative pressure (a pressure less than the ambient pressure) is established in the clamping area 353. Because the pressure in the clamping area 353 is lower than the pressure above the substrate W, a force is applied to the substrate W toward the substrate support 300, so that the substrate W is clamped to the substrate support 300. The force is applied radially inwardly along the multifunctional liquid introduction groove 361. This means that the clamping force can be applied while the edge lifting force is applied.

[0109] At some point, the substrate support 300 transitions from the loading state to a "clamping state". This clamping state is an example of a "normal state". Preferably, the substrate support 300 transitions from the loading state to the clamping state in response to the pressure measurement in the clamping region 353. Specifically, when the pressure measurement in the clamping region 353 decreases below a predefined threshold, the substrate support 300 transitions from the loading state to the clamping state. However, the present invention is not limited thereto, and the substrate support 300 may transition from the loading state to the clamping state in response to other measurements or in response to a predetermined timing.

[0110] In the clamped state ( Figure 8 ), the multifunctional opening 361 can extract gas from the multifunctional liquid introduction groove 351 so that a negative pressure is established in the multifunctional liquid introduction groove 351. This means that, as in the clamping area 353, a clamping force is applied to a portion of the lower side of the substrate W corresponding to the multifunctional liquid introduction groove 351. Alternatively, the multifunctional opening 361 can be closed so that it is not in fluid communication with any of the ambient pressure, overpressure or underpressure.

[0111] In the clamped state, ambient opening 364 and fluid extraction opening 362 are open. That is, ambient opening 364 is in fluid communication with ambient pressure, and fluid extraction opening 362 extracts fluid from fluid extraction gutter 352. Alternatively, ambient opening 364 may be in fluid communication with a positive pressure source. Figure 8 It is shown that when the substrate W is in the clamped state, the immersion fluid flowing through the gap 5 between the substrate W and the cover ring 301 also passes between the outer seal 333 and the underside of the substrate W and is present in the fluid extraction gutter 352. It is this immersion fluid that is extracted by the fluid extraction opening 362. The fluid extraction opening 362, the extraction pressure of the middle seal 332 and the ambient pressure in the ambient gutter 354 prevent the immersion fluid from flowing radially inwardly of the middle seal 332.

[0112] It is important that the immersion fluid cannot flow inward to reach the multi-function liquid gutter 351 or the multi-function opening 361 because when the multi-function opening 261 supplies gas, the immersion fluid will be blown toward critical surfaces such as the grid plate, sensors (transmission image sensor (TIS), integrated lens interferometer scanner (ILLIAS), parallel ILLIAS (PARIS)), and the top side of the substrate W. This may cause serious system performance issues such as stage positioning measurement (SPM) errors and substrate defects. In the present invention, when the substrate support 300 is in the clamped state, there are two seals (middle seal 332 and inner-middle seal 334) between the multi-function liquid gutter 351 and the immersion fluid. This means that the immersion fluid is less likely to reach the multi-function liquid gutter 351 compared to the comparative example, in which there is only one seal (middle seal 232) between the immersion fluid and the multi-function liquid gutter 251.

[0113] In the clamping state, the clamping opening 363 may continue to extract gas, so that the magnitude of the pressure difference between the clamping region 353 and the region above the substrate W increases. Alternatively, the clamping opening 363 may be closed, and the pressure magnitude within the clamping region 353 may remain substantially constant. As yet another alternative, gas may be periodically extracted through the clamping opening 363, so that the pressure magnitude within the clamping region 353 remains substantially constant.

[0114] The substrate support 300 may also be configured to operate in a "bypass state" (see Fig. 9), which is an alternative to the clamping state. In the bypass state, the clamping opening 363 and the multifunctional open fluid extraction opening 362 operate as in the clamping state. However, the ambient opening 364 can be closed. This means that the ambient opening 364 and the ambient liquid draw groove 354 are not in fluid communication with the ambient pressure. Alternatively, the ambient opening 364 can remain open but in fluid communication with a pressure source that is insufficient to prevent the immersion fluid from traveling radially inward beyond the middle seal 332. Therefore, the immersion fluid surrounds the outer circumferential ring of the middle seal 332 and the burl 342. In this bypass state, the multifunctional opening 361 supplies ambient pressure or positive pressure to the multifunctional liquid draw groove 351 to prevent the immersion fluid from traveling radially inward beyond the inner-middle seal 334 toward the clamping area 353. In some cases, it may be preferred that the outer circumferential ring of the burl 342 is "wet" because the "wet" outer circumferential ring of the burl 342 affects the friction between the distal end of the burl 342 and the underside of the substrate W.

[0115] In an embodiment, the following operations are performed to unload the substrate W from the substrate support 300. First, the immersion liquid around the substrate W is removed. The manner of removing the immersion liquid is not particularly limited. It can be performed by the channel 13 in the fluid handling structure IH, such as Figure 2 As shown, or it can be performed by the porous member 33 in the fluid handling structure IH, as Figure 3 As shown. Then, the multifunctional opening 361 is switched to supply gas to the multifunctional liquid introduction groove 351, so that the pressure in the multifunctional liquid introduction groove 351 increases, as in the loading phase. Therefore, the pressure in the multifunctional liquid introduction groove 351 becomes greater than the ambient pressure. Because the pressure in the multifunctional liquid introduction groove 351 is greater than the pressure above the substrate W, a force is applied to the lower side of the substrate W in an upward direction (i.e., in a direction away from the substrate support 300).

[0116] Next, the clamping opening 363 is closed. As a result, the pressure within the clamping region 353 gradually increases toward the ambient pressure, so that the clamping force applied to the substrate W is reduced. In order to remove the substrate W from the substrate support 300, the e-pins (not shown) are extended from their retracted positions. As the e-pins are extended, their distal end portions contact the underside of the substrate W. As the e-pins continue to extend, the substrate W is lifted off the plurality of burls 341, 342.

[0117] In an embodiment, when the substrate W is supported by the substrate support 300 , the top surfaces of the plurality of seals 331 , 332, 333, 334 (i.e., the surfaces of the plurality of seals 331 , 332, 333, 334 that are substantially parallel to the substrate W and closest to the substrate W) do not contact the underside of the substrate W. However, the distance between the top surfaces of the plurality of seals 331 , 332, 333, 334 and the underside of the substrate W is such that at least a partial seal is formed between the top surfaces of the seals 331 , 332, 333, 334 and the underside of the substrate W. That is, the plurality of seals 331 , 332, 333, 334 inhibit, but do not completely prevent, the flow of fluid between the plurality of liquid guttering grooves 351 , 352, 354 and the clamping area 353 .

[0118] The distance between the top surface of the seals 331 , 332, 333, 334 and the underside of the substrate W is preferably less than 10 μm and further preferably less than 5 μm, and is preferably greater than 1 μm and further preferably greater than 3 μm.

[0119] In an embodiment, the distance between the top surface of the seal 331, 332, 333, 334 and the lower side of the substrate W may be different for each seal 331, 332, 333, 334. For example, for the seals defining the multifunctional liquid drain groove 351 (i.e., the inner seal 331 and the inner-middle seal 334), the distance between the top surface of the seal and the lower side of the substrate W may be smaller. This is to limit the flow of fluid from the multifunctional liquid drain groove 351 to other areas, which enables a higher pressure to be built in the multifunctional liquid drain groove 351 to provide an edge lift function. Further, limiting the flow through the inner seal 331 and the inner-middle seal 334 is beneficial to isolate the multifunctional liquid drain groove 351 and the clamping area 353 from the environmental liquid drain groove 354. In order to optimize the substrate support 300 for the clamping state, the distance between the top surface of the outer seal 333 and the lower side of the substrate W may be smaller than the distance between the top surface of the middle seal 332 and the lower side of the substrate W. In order to optimize the substrate support 300 for the bypass state, the distance between the top surface of the intermediate seal 332 and the underside of the substrate W can be made smaller. This is to increase the capillary forces on the immersion fluid in the gap between the intermediate seal 332 and the substrate W, ensuring that the intermediate seal 332 is surrounded by the immersion fluid and the burls 342 are "wet".

[0120] In the present invention, the edge lift force is applied to the lower side of the substrate W in the area corresponding to the multifunctional liquid introduction groove 351 between the inner seal 331 and the inner-middle seal 334. During the clamping state, the atmospheric pressure or overpressure required to prevent the immersion fluid from flowing radially inwardly of the middle seal 332 is supplied by the environmental opening 364. Between the multifunctional opening 361 and the environmental opening 364 is the inner-middle seal 334. This means that the magnitude of the edge lift force depends on the distance between the inner seal 331 and the inner-middle seal 334, and the size of the flatness ridge depends on the distance between the inner-middle seal 334 and the middle seal 332. Therefore, the distance between the inner seal 331 and the inner-middle seal 334 (i.e., the size of the multifunctional liquid introduction groove 351) can be made large enough to provide sufficient edge lift force in the loaded state.

[0121] Separately, when the substrate support 300 is in the clamped state, the distance between the inner-middle seal 334 and the middle seal 332 can be made small enough to minimize the flatness ridge in the substrate W. This is different from the comparative example, in which the multifunctional opening 261 provides the ambient pressure or overpressure required to prevent the immersion fluid from flowing radially inwardly of the middle seal 232. This means that in the present invention, the problem that the distance between the inner seal 231 and the middle seal 232 cannot meet the edge lift force requirement and the flatness requirement exhibited in the comparative example is avoided.

[0122] Taking this into account, in an embodiment, the distance between the inner seal 331 and the inner-middle seal 334 is greater than the distance between the inner-middle seal 334 and the middle seal 332 and the distance between the middle seal 332 and the outer seal 333. For a substrate support 300 configured to support a substrate W having a diameter of 300 mm, the following dimensions are preferred. The radial distance between the inner seal 331 and the inner-middle seal 334 should be greater than 0.5 mm, preferably greater than 1 mm, and preferably greater than 1.5 mm. This is to ensure that the edge lift force applied to the lower side of the substrate W in the area corresponding to the multi-functional liquid gutter 351 is sufficient to deform the edge of the substrate W, so that it can be ensured that when the substrate support 300 is in a loaded state, the outer circumferential ring of the protrusion 342 is the last point of contact with the lower side of the substrate W. Preferably, the distance between the inner seal 331 and the inner-middle seal 334 is less than 10 mm.

[0123] The distance between the inner-middle seal 334 and the middle seal 332, the distance between the middle seal 332 and the outer seal 333, and the distance between the outer seal 333 and the circumferential edge of the substrate W should be small enough to bring the multifunctional liquid gutter sufficiently close to the edge of the substrate W. In this context, “sufficiently close” means close enough to apply an edge lifting force on the lower side of the substrate W in the area corresponding to the multifunctional liquid gutter 351, so that the edge area of ​​the substrate W is deformed upward, and it can be ensured that the outer circumferential ring of the protrusion 342 is the last point in contact with the lower side of the substrate W when the substrate support 300 is in a loaded state.

[0124] Preferably, the distance between the inner-middle seal 334 and the middle seal 332 is less than 1 mm, further preferably less than 0.8 mm, and further preferably less than 0.6 mm. Preferably, the distance between the inner-middle seal 334 and the middle seal 332 is greater than 0.2 mm. As discussed above, this distance is to ensure that the multi-functional liquid introduction groove 351 is sufficiently close to the circumferential edge of the substrate W, and when the substrate W is clamped to the substrate support 300, this distance is also to minimize the flatness ridge between the inner-middle seal 334 and the middle seal 332 in the substrate W.

[0125] The distance between the center of the middle seal 332 in the radial direction and the center of the outer seal 333 in the radial direction may be about half of the burl pitch (the distance between the plurality of burls 341). That is, the distance between the center of the middle seal 332 in the radial direction and the center of the outer seal 333 in the radial direction is preferably greater than 30% of the burl pitch, further preferably greater than 40% of the burl pitch, and further preferably greater than 45% of the burl pitch. The distance between the center of the middle seal 332 in the radial direction and the center of the outer seal 333 in the radial direction is preferably less than 70% of the burl pitch, further preferably less than 60% of the burl pitch, and further preferably less than 55% of the burl pitch. For example, in the case where the burl pitch is 1.5 mm, the distance between the center of the middle seal 332 in the radial direction and the center of the outer seal 333 in the radial direction is preferably greater than 0.45 mm, further preferably greater than 0.6 mm, and further preferably greater than 0.68 mm. In this case, the distance between the center of the middle seal 332 in the radial direction and the center of the outer seal 333 in the radial direction is preferably less than 1.05 mm, further preferably less than 0.9 mm, and further preferably less than 0.83 mm. As mentioned above, the distance between the center of the middle seal 332 in the radial direction and the center of the outer seal 333 in the radial direction is small to ensure that the multifunctional liquid introduction groove 351 is sufficiently close to the edge of the substrate W. In addition, the above-specified range ensures that the bending moment acting on the substrate W is balanced, thereby ensuring the optimal flatness of the substrate W.

[0126] Further, the distance between the outer seal 333 and the circumferential edge of the substrate W is preferably less than 5 mm, further preferably less than 3 mm, and further preferably less than 2.5 mm. The distance between the outer seal 333 and the circumferential edge of the substrate W is preferably greater than 1 mm. Again, as discussed above, this distance is small to ensure that the multifunctional liquid guide groove 351 is sufficiently close to the circumferential edge of the substrate W.

[0127] For substrates W having a diameter other than 300 mm, the dimensions should be scaled according to the diameter of the substrate W. Typically, the distance between the inner seal 331 and the inner-intermediate seal 334 should be greater than 0.15% of the diameter of the substrate W, preferably greater than 0.3% of the diameter of the substrate W, and further preferably greater than 0.5% of the diameter of the substrate W, and less than 3.3% of the diameter of the substrate W. The distance between the inner-intermediate seal 334 and the intermediate seal 332 should be less than 0.5% of the diameter of the substrate W, preferably less than 0.25% of the diameter of the substrate W, and further preferably less than 0.2% of the diameter of the substrate W, and should be greater than 0.05% of the diameter of the substrate W. Further, the distance between the outer seal 333 and the edge of the substrate W is preferably less than 1.7% of the diameter of the substrate W, further preferably less than 1% of the diameter of the substrate W, and further preferably less than 0.8% of the diameter of the substrate W. The distance between the outer seal 333 and the circumferential edge of the substrate W is preferably greater than 0.3% of the diameter of the substrate W.

[0128] It should be noted that the range cited above for the distance between the radial center of the middle seal 332 and the radial center of the outer seal 333 is not limited to being advantageous in the above embodiments. For example, the range can be implemented in the substrate support 200 of the comparative example to produce the same technical effect (balancing the bending moment to ensure the flatness of the substrate W).

[0129] The width of each seal of the plurality of seals 331, 332, 333, 334 (i.e., the distance between the inner circumferential edge of the seal and the outer circumferential edge of the seal in the radial direction) is preferably greater than 0.1 mm, and further preferably greater than 0.2 mm. The width of each seal of the plurality of seals 331, 332, 333, 334 is preferably less than 1 mm, and further preferably less than 0.6 mm.

[0130] The width of each seal in the plurality of seals 331, 332, 333, 334 may be different. The width of some seals may be made larger to ensure that the ring of the burl 342 can be located on the top surface of the seal 332. In an embodiment, the width of the middle seal 332 and the outer seal 333 is greater than the width of the inner seal 331 and the inner-middle seal 334. Preferably, the width of the middle seal 332 and the outer seal is greater than 0.4 mm and less than 0.6 mm, such as 0.5 mm. The width of the inner seal 331 and the inner-middle seal 334 is preferably less than 0.3 mm and greater than 0.2 mm, such as 0.25 mm.

[0131] In an embodiment, a plurality of burls 341 are arranged in a circumferential ring. The radially outermost circumferential ring of burls 342 may be located on or around the intermediate seal 332. This is because, when the substrate support 300 supports the substrate W, preferably the outer circumferential ring of burls 342 remains dry, i.e., not in contact with the immersion fluid. This is to prevent wear of the outer circumferential ring of burls 342 and reduce the risk of edge roll-off (ERO).

[0132] In an embodiment, when a substrate W having a diameter of 300 mm is clamped onto the substrate support 300 , the radially outermost circumferential ring of the burls 342 is preferably less than 10 mm from the circumferential edge of the substrate W, further preferably less than 5 mm from the circumferential edge of the substrate W, further preferably less than 4 mm from the circumferential edge of the substrate W, and further preferably less than 3.5 mm from the circumferential edge of the substrate W. When a substrate W having a diameter of 300 mm is clamped onto the substrate support 300 , the radially outermost circumferential ring of the burls 342 is preferably more than 1 mm away from the circumferential edge of the substrate W.

[0133] The diameter of each of the burls 341, 342 may be different. For example, each circumferential ring of burls 342 to 346 may have a different diameter. The diameter of the burls 342 to 346 in the circumferential ring may depend on the radial distance from the center of the substrate support 300. This is because the stiffness of the burl is proportional to its diameter. Therefore, by changing the diameter of the burls 341, 342, the amount of deformation at the burl-substrate interface can be adjusted. This means that despite the complex pressure distribution on the underside of the substrate W, the diameter of the burls 341, 342 can be controlled to ensure that the substrate W remains within the desired flatness tolerance. The required diameter of each ring of burls 342 to 346 can be determined by optimization through experiments or simulations.

[0134] Fig.10Five outer circumferential burls 342 to 346 are shown. In an embodiment, the diameter of the burl 342 in the radially outermost circumferential ring is greater than the diameter of the burl 341 in the other circumferential rings. In another embodiment, the diameter of the radially outermost circumferential ring of burl 342, the third radially outermost circumferential ring of burl 344, and the fourth radially outermost circumferential ring 345 is greater than the diameter of the burls in the other circumferential rings 343, 346. Preferably, the diameter of the burls in the radially outermost circumferential ring 342, the third radially outermost circumferential ring 344, and the fourth radially outermost circumferential ring 345 is between 200 μm and 350 μm, and the diameter of the burls in the other rings 343, 346 is between 150 μm and 250 μm. It is further preferred that the diameter of the burls in the radially outermost circumferential ring 342, the third radially outermost circumferential ring 344, and the fourth radially outermost circumferential ring 345 is between 250 μm and 330 μm, and the diameter of the burls in the other circumferential rings 343, 346 is between 190 μm and 240 μm. It is further preferred that the diameter of the burls in the radially outermost circumferential ring 342, the third radially outermost circumferential ring 344, and the fourth radially outermost circumferential ring 345 is between 260 μm and 280 μm, such as 270 μm, and the diameter of the burls in the other rings 343, 346 is between 200 μm and 220 μm, such as 210 μm.

[0135] Depending on the configuration of the substrate support 300, the ratio of the diameter of the burls 341 relative to the other burls 341 may be important to ensure flatness of the substrate W. With this in mind, in an embodiment, the diameter of the burls in the radially outermost circumferential ring 342, the third radially outermost circumferential ring 344, and the fourth radially outermost circumferential ring 345 is greater than the diameter of the burls in the other rings 343, 346 by more than 10%, preferably greater than the diameter of the burls in the other rings 343, 346 by more than 20%, and further preferably greater than the diameter of the burls in the other rings 343, 346 by more than 25%. In an embodiment, the diameter of the burls 342, 344, 345 is less than 100% greater than the diameter of the burls in the other rings 343, 346, preferably less than 50% of the diameter of the burls in the other rings 343, 346, and further preferably less than 30% of the diameter of the burls in the other rings 343, 346.

[0136] When adjusting the relative ratio of the diameters of the burls 341, 342, it is preferred to increase the diameters of the burls 341, 342 rather than decrease the diameters of the burls 341, 342. This is because burls 341, 342 with smaller diameters may wear faster, which means that the substrate support 300 (or support body 321) needs to be replaced more frequently. In order to avoid the burls 341, 342 from wearing too quickly, the diameters of all burls 341, 342 should be greater than 150 μm.

[0137] Other techniques can be used to adjust the stiffness of the burls 341, 342, such as changing the material or applying a coating, such as diamond and DLC. However, the stiffness of the substrate W is generally lower than the stiffness of the burls 341, 342, so the deformation at the substrate-burl interface is not significantly affected by the burl material or coating. Therefore, these techniques are not particularly effective for controlling the flatness of the substrate W.

[0138] In the above embodiments, the burl pitch (the distance between burls 341, 342) is preferably greater than 0.5 mm, further preferably greater than 1 mm, and further preferably greater than 1.4 mm. The burl pitch is preferably less than 3 mm, further preferably less than 2 mm, and further preferably less than 1.6 mm, such as 1.5 mm.

[0139] Controlling the flatness of the substrate W on the substrate support 300 by adjusting the burl diameter depending on the radial position of the burl is not limited to the arrangement of seals 331, 332, 333, 334 described in the present invention. The technique and the dimensions given above can be implemented in various substrate supports 300 with different sealing arrangements.

[0140] The height of the burl 341 (ie, the dimension from the surface of the support body 321 to the distal end of the burl) may be approximately 150 μm. However, the burl 341 may be of any suitable height.

[0141] The gas supplied through the openings 361, 362, 363, 364 (e.g., supplied through the multifunctional opening 361 in the loading state and supplied through the ambient opening 364 in the clamping state) is not particularly limited. For example, clean dry air (CDA), humidified air or N2 may be supplied. Preferably, humidified air is supplied in the loading state, in particular through the ambient opening 364. This is because CDA with very low humidity may cause any immersion fluid on the outer seal 333 to evaporate, thereby generating a large cold load on the outer seal 333. This may cause transient structural deformation of the substrate support 300, which may result in overlap loss. Humidified air means that less immersion fluid evaporates from around the outer seal 333, and the cold load is reduced.

[0142] exist Figure 5 and 6In the substrate support 200 of the illustrated comparative example, supplying humidified air to the multifunctional opening 261 during the clamping state is not preferred, because there is a risk that the humidity will move radially inwards towards the clamping region 253, which may cause electrochemical reactions on the burls 341 in the clamping region 353, resulting in a flatness drift of the substrate W. However, in the present invention, there are two seals (inner seal 331 and inner-middle seal 334) between the ambient opening 364 (to which humidified air is supplied in the clamping state) and the clamping region 353. This significantly inhibits any humidity entering through the ambient opening 364 from reaching the clamping region 353. The presence of these two seals 331, 334 between the ambient opening 364 and the clamping region 353 also minimizes the risk of uncontrolled air (air containing contaminants and / or uncontrolled temperature) flowing between the substrate W and the substrate support 300.

[0143] In the above description, a single opening 361, 362, 363, 364 is mentioned in each of the liquid extraction groove areas 351, 352, 354 and the clamping area 353. The openings 361, 362, 363, 364 can extend circumferentially around the substrate support 300. Alternatively, the openings 361, 362, 363, 364 can be circular holes. Preferably, a plurality of hole-shaped openings are evenly distributed around each area 351, 352, 353, 354. In the case where there are multiple hole-shaped openings in each area, each opening in a region can be configured in the same manner (i.e., in the manner of the openings already defined in a given area). For example, there may be multiple openings in the fluid extraction liquid extraction groove 352, each of which is configured to extract fluid in the same manner as the fluid extraction opening 362. However, the additional openings can be configured to operate in a different manner from the already defined openings. For example, the fluid extraction liquid extraction groove 352 can also include an opening configured to supply fluid. The multifunctional opening 361 in the multifunctional liquid introduction groove 351 is configured to supply and / or extract gas. In the case where there are multiple openings in the multifunctional liquid introduction groove 351, each opening can be configured to extract and supply gas. Alternatively, some openings can be configured to only supply gas, while other openings can be configured to only extract gas.

[0144] The multifunctional opening 361 is a restrictive feature in the fluid circuit. Therefore, the diameter of the multifunctional opening 361 can be smaller than the diameter of the environmental opening 364. Preferably, the diameter of the multifunctional opening 361 is between 100 μm and 200 μm. For the other openings 362, 363, 364, the diameter is not particularly limited. Preferably, their diameter is larger to allow fluid to flow freely through them and minimize the risk of obstruction. However, the diameter of these openings 362, 363, 364 must be small enough to fit between the seals.

[0145] The mechanism for opening and closing these openings 361, 362, 363, 364 is not particularly limited, and any standard valve or equivalent may be used. Similarly, the system for supplying gas to and extracting gas from the openings 361, 362, 363, 364 (providing positive and negative pressures) is not particularly limited, and may involve any suitable standard components or methods.

[0146] <Multi-function channel>

[0147] As mentioned above Figure 4 As explained, the openings 107, 117 on the upper surface of the substrate support WT may be connected to channels 102, 113 within the substrate support WT via passages 103, 114. The passages 102, 113 may be cavities extending around the circumference of the substrate support WT, allowing fluid to be transported between the openings 107, 117 in the substrate support WT and, for example, a fluid management system external to the substrate support WT. The passages 103, 114 may be substantially vertical holes extending upward from the passages 102, 113 to the openings 107, 117, facilitating fluid communication therebetween.

[0148] Fig.11A An example of a channel is depicted. The depicted channel may be a multi-function channel 381. Fig.11A As shown, a plurality of multifunctional passages 371 may extend vertically upward from a multifunctional channel 381. The opening at the end of the multifunctional passage 371 opposite the multifunctional channel 381 may be a multifunctional opening 361. The multifunctional channel 381 may be connected to an external fluid management system 391 at a connection point 382. The fluid management system 391 may control the flow of fluid into and out of the multifunctional channel 381. The fluid management system 391 may include, for example, a flow restrictor (not shown).

[0149] The multifunctional channel 381 may be circular, but not form a complete circle. This may be because there is a break 385 in the loop formed by the multifunctional channel 381. This may mean that fluid cannot flow from the fluid management system 391 all the way around the multifunctional channel 381 without changing direction. The break 385 may be located on the side of the multifunctional channel 381 opposite the connection point 382. That is, the break 385 in the multifunctional channel 381 and the connection point 382 may be separated by approximately 180°.

[0150] To provide the above-mentioned edge lift force, gas can flow from the fluid management system 391 into the multi-function channel 381 via the connection point 382. After entering the multi-function channel 381, the gas flow may split, with about half of the gas flow going to the right (i.e., as shown in FIG. Fig.11A counterclockwise as shown), and the other half flows to the left (i.e., Fig.11A381). When the gas flow passes through the multifunctional passage 371, a portion of the gas flow will flow upward through the multifunctional passage 371. Then, this portion of the gas flow will flow through the multifunctional opening 361 and enter the multifunctional liquid introduction groove 351, causing the pressure in the multifunctional liquid introduction groove 351 to increase. The left and right gas flows can travel around the multifunctional channel 381 until reaching the interruption 385. In this way, the left and right flows of gas can each travel halfway around the multifunctional channel 381, so that all multifunctional passages 371 are supplied with gas. In this way, an edge lift force can be provided around the entire circumference of the substrate W.

[0151] In order to effectively provide the edge lift functionality, it is desirable that the flow rate through each of the multifunctional passages 371 is substantially the same. If the flow rate in each of the multifunctional passages 371 is not the same, particularly if the flow rate of the multifunctional passages 371 in some areas is greater than the flow rate of the multifunctional passages 371 in other areas, providing the edge lift force may cause the substrate W to tilt during loading. In order to ensure that the flow rate in each of the multifunctional passages 371 is substantially the same, it is desirable that the flow rate within the multifunctional channel 381 is substantially uniform around its circumference.

[0152] Due to restrictive geometric constraints within the body of the substrate support WT, the multifunctional channel 381 and the multifunctional passage 371 may be small. The restrictive geometric constraints exist because many features must be accommodated within the body of the substrate support WT, such as channels corresponding to each of the different types of openings, cooling channels, heaters, etc.

[0153] Due to the small size of the multifunctional channel 381, pressure loss may occur when the gas flow flows from the fluid management system 391 to the multifunctional opening 361. That is, the fluid pressure in the multifunctional channel 381 may increase as the distance from the connection point 382 increases. For example, there may be a pressure difference of about 0.01 to 0.05 bar (1 to 5 kPa) between the connection point 382 and the portion of the multifunctional channel 381 adjacent to the interruption 385. This may mean that the edge lift force provided to a portion of the substrate W located near the connection point 382 is greater than the edge lift force provided to a portion of the substrate W located near the interruption 385. Providing an uneven edge lift force may result in a non-zero resultant moment being applied to the substrate W, causing the substrate W to tilt during loading.

[0154] Further, the pressure difference within the multifunctional channel 381 may cause deformation of the substrate support WT. As a result, the flatness of the substrate support WT and any substrate W supported by the substrate support WT may be reduced. This may cause defects in the pattern printed on the substrate W. Further, if the substrate support WT is formed of two or more layers laminated together, the high pressure difference within the multifunctional channel 381 may cause these layers to delaminate.

[0155] In order to improve the uniformity of the edge lift force around the circumference of the substrate W (despite the pressure changes within the multifunctional channel 381), the multifunctional opening 361 can be small to limit the flow through it. For example, the diameter of the multifunctional opening 361 is about 0.15 mm. This means that the risk of clogging is high. Further, this means that the multifunctional opening 361 needs to be manufactured with high accuracy (i.e., low tolerance) because any deviation in its diameter may cause the flow through it to vary when the edge lift force is provided. The need for the multifunctional opening 361 to be manufactured with low tolerances means that the manufacturing and cleaning processes may be complicated. Further, if the multifunctional opening 361 is not manufactured accurately, or if the multifunctional opening 361 is blocked, the uneven edge lift force applied to the substrate W may cause the substrate W to deform.

[0156] Fig. 11B An alternative arrangement for providing fluid to the multi-function opening 361 is depicted. Fig. 11B In the embodiment, three multifunctional channels 381a, 381b, 381c are provided. Each of the multifunctional channels 381a, 381b, 381c can correspond to a part of the circumference of the substrate support WT, so that the multifunctional channels 381a, 381b, 381c can provide fluid to the multifunctional passage 371 around the entire circumference of the substrate support WT. The size of each multifunctional channel in the multifunctional channels 381a, 381b, 381c can be the same. For example, the three multifunctional channels 381a, 381b, 381c can correspond to approximately 120° of the circumference of the substrate support WT, respectively. Between each of the multifunctional channels in the multifunctional channels 381a, 381b, 381c, there may be interruptions 385ac, 385ab, 385bc. Each multifunctional channel 381a, 381b, 381c can be directly connected to the fluid management system 391. That is, each multifunctional channel 381a, 381b, 381c can be connected to the fluid management system 391 via its own connection component (e.g., pipe or tube). The connection point 382a, 382b, 382c of each of the multifunctional channels 381a, 381b, 381c can be located approximately in the middle of the multifunctional channel 381a, 381b, 381c.

[0157] By providing a plurality of multifunctional channels 381a, 381b, 381 as described above, it is possible to suppress the tilting of the substrate W. This is because, even if the flow rate in each multifunctional channel 381a, 381b, 381c is not uniform, the tilting moments applied to the substrate W cancel each other, so that the resultant moment when the substrate W is flat is approximately zero.

[0158] Furthermore, by providing a plurality of multifunctional channels 381a, 381b, 381c, the size (along the circumferential direction) of each multifunctional channel 381a, 381b, 381c can be made smaller compared to a configuration in which there is a single multifunctional channel 381. For example, in a configuration having three multifunctional channels 381a, 381b, 381c, the size (along the circumferential direction) of each multifunctional channel 381a, 381b, 381c can be one third of the size (along the circumferential direction) of a configuration in which there is a single multifunctional channel 381.

[0159] Furthermore, by providing a plurality of multifunctional channels 381a, 381b, 381c, the flow rate of each multifunctional channel 381a, 381b, 381c can be made smaller compared to a configuration in which there is a single multifunctional channel 381. For example, in a configuration having three multifunctional channels 381a, 381b, 381c, the flow rate of each multifunctional channel 381a, 381b, 381c can be one third of the flow rate within the multifunctional channel in a configuration in which there is only a single multifunctional channel 381.

[0160] The reduced flow rate in the multifunctional channels 381a, 381b, 381c means that the pressure of the fluid flowing through the multifunctional channels 381a, 381b, 381c is reduced to a lesser extent. This means that the pressure difference in the multifunctional channels 381a, 381b, 381c is smaller (compared to the pressure difference in the multifunctional channel 381 in the configuration with only one multifunctional channel 381). This means that the occurrence of substrate support warping and / or bonding layer delamination can be reduced. This also means that a multifunctional opening 361 with a larger diameter can be provided without reducing the uniformity of the edge lift force provided to the lower side of the substrate W. By being able to increase the diameter of the multifunctional opening 361, the possibility of clogging is reduced, and the manufacturing and cleaning processes can be made simpler.

[0161] Fluid management system 391 may include an adjustable restrictor for each multifunctional channel in multifunctional channels 381a, 381b, 381c. The adjustable restrictor may be configured so that the flow rate of the fluid provided to each multifunctional channel in three multifunctional channels 381a, 381b, 381c can be adjusted individually. The adjustable restrictor may be electric and / or mechanical. The exact configuration of the adjustable restrictor may not be particularly limited. Using the adjustable restrictor, it may be possible to calibrate the flow rate provided to each multifunctional channel in multifunctional channels 381a, 381b, 381c to ensure that the edge lift force of each part in the three parts of the substrate W corresponding to the three multifunctional channels 381a, 381b, 381c is the same. By doing so, it can be further ensured that the substrate W will not tilt during loading. The calibration process can take into account factors such as the change in the size of the multifunctional opening 361 and the multifunctional opening 361 that are blocked. Thus, by providing a plurality of multifunctional channels 381a, 381b, 381c, it can be ensured that the substrate W does not tilt, even if there are blocked multifunctional openings 361 and variations in the size of the multifunctional openings 361. This means that the operation of the multifunctional openings 361 is more robust, as manufacturing errors and blockages can be mitigated. This in turn means that manufacturing tolerances can be increased (i.e., relaxed), and the manufacturing process can be made less complicated.

[0162] Fig.12 The moment about the horizontal axis (M) and the tilt angle (θ) are plotted for a substrate support WT having a single multifunctional channel and a substrate support WT having three multifunctional channels 381a, 381b, 381c at several flow conditions. Specifically, when the flow rate in the multifunctional channel 381 is 0 NLM (normal liters per minute), 1.5 NLM, and 5 NLM, Fig.12 The various dashed lines in FIG. 3 correspond to a substrate support WT having a single multifunctional channel 381. When the sum of the flow rates in the three multifunctional channels 381a, 381b, 381c is 5 NLM, Fig.12 The solid line in corresponds to a substrate support WT having three multifunctional channels 381a, 381b, 381c.

[0163] When the substrate W is loaded onto the substrate support WT, the tilt angle of the substrate W will be the tilt angle, which means that the resultant moment about the horizontal axis is zero. This tilt angle can be called the stable tilt angle. For a substrate support WT with a single multifunctional channel 381, the magnitude of the stable tilt angle will also increase as the flow rate increases. When the flow rate through the single multifunctional channel 381 is 0 NLM, the stable tilt angle may not be zero due to the influence of other openings in the substrate support WT (such as the clamping opening 363). For a substrate support WT with three multifunctional channels 381a, 381b, 381c, the stable tilt angle at a flow rate of 5 NLM may be 10 times smaller than that of a substrate support WT with a single multifunctional channel 381. The stable tilt angle of a substrate support WT with three multifunctional channels 381a, 381b, 381c at 5 NLM may not be zero. This may be due to the influence of other openings in the substrate support WT, such as the clamping opening 363.

[0164] Although the device of multiple multifunctional channels has been described above with reference to a configuration having three multifunctional channels 381a, 381b, 381c, the above technical effects can be achieved by providing a configuration in which the number of multifunctional channels is 2 or more. For example, the number of multifunctional channels can be 2, 3, 4, 5 or 10. Providing more multifunctional channels may mean that more control is obtained over the tilting of the substrate W, and the pressure difference within the multifunctional channels 381a, 381b, 381c can be further reduced. However, providing more multifunctional channels 381a, 381b, 381c may also make the substrate support WT more difficult to manufacture. By providing three multifunctional channels 381a, 381b, 381c, the above technical effects are achieved without making the manufacturing process too complicated.

[0165] Although the provision of multiple channels has been described above with respect to the multi-function channel 381, the technique may also be implemented for other channels within the substrate support WT.

[0166] <Summary>

[0167] The material of the substrate support 300 is not particularly limited, and may be any suitable material known in the art. Preferably, the substrate support 300 may be made of silicon carbide (SiSiC).

[0168] The manufacture of the substrate support 300 may involve standard techniques known in the art. Some of the openings 361 , 362 , 363 , 364 may be too small for methods such as electrical discharge machining (EDM). In this case, laser drilling may be used.

[0169] The present invention may provide a lithographic apparatus. The lithographic apparatus may have any / all other features or components of the above-mentioned lithographic apparatus. For example, the lithographic apparatus may optionally include at least one or more of a source SO, an illumination system IL, a projection system PS, a substrate table WT, etc.

[0170] In particular, the lithographic apparatus may include a projection system PS configured to project a radiation beam B towards a surface area of ​​a substrate W. The lithographic apparatus may further include a substrate support 300 as described in any one of the above embodiments and variations.

[0171] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

[0172] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented by instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or sending information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include a read-only memory (ROM); a random access memory (RAM); a magnetic storage medium; an optical storage medium; a flash memory device; an electrical, optical, acoustic, or other form of propagation signal (e.g., a carrier wave, an infrared signal, a digital signal, 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 that executes firmware, software, routines, instructions, etc., and doing so may cause an actuator or other device to interact with the physical world.

[0173] Although embodiments of the invention may be specifically referenced herein in the context of lithographic equipment, embodiments of the invention may be used in other equipment. Embodiments of the invention may form part of a mask inspection equipment, a metrology equipment, or any equipment that measures or processes objects such as wafers (or other substrates) or masks (or other pattern forming devices). These equipment may generally be referred to as lithographic tools.

[0174] Although specific reference may have been made above to the use of embodiments of the present invention in the context of optical lithography, it will be appreciated that the present invention is not limited to optical lithography where the context permits.

[0175] Although specific embodiments of the present invention have been described above, it is to be understood that the present invention may be practiced in a manner other than that described. The above description is intended to be illustrative, not restrictive. Therefore, it will be apparent to those skilled in the art that modifications may be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A substrate support configured to support a substrate in a lithographic apparatus, the substrate support comprising: a first circumferential wall; a first opening, radially outside the first circumferential wall and configured to supply and / or extract gas; a second circumferential wall, radially outward of the first opening; a second opening in fluid communication with ambient pressure and radially outward of the second circumferential wall; a third circumferential wall, radially outward of the second opening; a third opening radially outward of the third circumferential wall and configured to extract a fluid; as well as The fourth circumferential wall is located radially outside the third opening.

2. The substrate support according to claim 1, further comprising: A fourth opening radially inwardly of the first circumferential wall is configured to extract gas, and / or wherein the substrate support is configured such that the first circumferential wall, the second circumferential wall, the third circumferential wall and the fourth circumferential wall form at least a partial seal with the bottom surface of the substrate.

3. The substrate support according to claim 2, wherein the distance between the bottom surface of the substrate and the top surfaces of the third circumferential wall and the fourth circumferential wall is greater than the distance between the bottom surface of the substrate and the top surfaces of the first circumferential wall and the second circumferential wall, and / or wherein the distance between the bottom surface of the substrate and the top surface of at least one of the first circumferential wall, the second circumferential wall, the third circumferential wall and the fourth circumferential wall is between 1 and 10 μm, preferably between 1 and 5 μm, and further preferably between 3 and 5 μm.

4. A substrate support according to any of the preceding claims, wherein the substrate support is configured so that when gas is supplied by the first opening, the pressure in a first region between the first circumferential wall and the second circumferential wall is greater than the ambient pressure around the substrate, and / or wherein the widths of the third circumferential wall and the fourth circumferential wall are greater than the widths of the first circumferential wall and the second circumferential wall, and / or wherein the distance between the first circumferential wall and the second circumferential wall is greater than the distance between the second circumferential wall and the third circumferential wall and the distance between the third circumferential wall and the fourth circumferential wall, and / or wherein the distance between the second circumferential wall and the third circumferential wall is less than 0.5% of the diameter of the substrate, preferably less than 0.25% of the diameter of the substrate, and further preferably less than 0.2% of the diameter of the substrate, and greater than 0.05% of the diameter of the substrate.

5. The substrate support according to claim 1 , wherein the distance between the first circumferential wall and the second circumferential wall is greater than 0.5 mm, preferably greater than 1 mm and further preferably greater than 1.5 mm, and less than 10 mm, and / or wherein the distance between the second circumferential wall and the third circumferential wall is less than 1 mm, preferably less than 0.8 mm and further preferably less than 0.6 mm, and greater than 0.2 mm, and / or wherein the distance between the first circumferential wall and the second circumferential wall is greater than 0.15% of the diameter of the substrate, preferably greater than 0.3% of the diameter of the substrate, and further preferably greater than 0.5% of the diameter of the substrate, and less than 3.3% of the diameter of the substrate, and / or wherein the distance between the center of the third circumferential wall in the radial direction and the center of the fourth circumferential wall in the radial direction is greater than 0.45 mm, preferably greater than 0.6 mm, and preferably greater than 0.68 mm, and less than 1.05 mm, preferably less than 0.9 mm, and further preferably less than 0.83 mm.

6. The substrate support of any one of the preceding claims, further comprising a plurality of burls arranged in a plurality of circumferential rings.

7. A substrate support according to claim 6, wherein the diameter of the protrusion depends on its radial position on the substrate support, and / or wherein the radially outermost circumferential ring of protrusions is located on or around the third circumferential wall, and / or wherein the diameter of the protrusions in the radially outermost circumferential ring, the third radially outermost circumferential ring and the fourth radially outermost circumferential ring is larger than the diameter of the protrusions in the other rings.

8. The substrate support according to claim 6 , wherein the diameter of the burls in the radially outermost circumferential ring, the third radially outermost circumferential ring and the fourth radially outermost circumferential ring is more than 10% larger than the diameter of the burls in the other rings, preferably more than 20% larger than the diameter of the burls in the other rings and further preferably more than 25% larger than the diameter of the burls in the other rings, and less than 100% larger than the diameter of the burls in the other rings, preferably less than 50% larger than the diameter of the burls in the other rings and further preferably less than 30% larger than the diameter of the burls in the other rings, and / or wherein the diameter of the burls in the radially outermost circumferential ring, the third radially outermost circumferential ring and the fourth radially outermost circumferential ring is between 200 µm and 350 µm and the diameter of the burls in the other rings is between 150 µm and 250 µm, preferably wherein the diameter of the burls in the radially outermost circumferential ring, the third radially outermost circumferential ring and the fourth radially outermost circumferential ring is between 250 µm and 330 Preferably, the diameters of the burls in the radially outermost circumferential ring, the third radially outermost circumferential ring and the fourth radially outermost circumferential ring are between 260 µm and 280 µm, and the diameters of the burls in the other rings are between 200 µm and 220 µm, and / or the distance between the radial center of the third circumferential wall and the radial center of the fourth circumferential wall is greater than 30% of the burl pitch, preferably greater than 40% of the burl pitch, and preferably greater than 45% of the burl pitch, and less than 70% of the burl pitch, preferably less than 60% of the burl pitch, and further preferably less than 55% of the burl pitch.

9. The substrate support according to any of the preceding claims, wherein the first opening has a smaller diameter than the second opening and / or wherein the second opening is additionally in fluid communication with a positive pressure source. 10 . The substrate support according to claim 9 , wherein the second opening is configured to supply dry or humidified gas.

11. A substrate support according to any one of the preceding claims, wherein the substrate support is made of SiSiC, and / or wherein there are a plurality of first openings distributed around the circumference of the substrate support, and wherein a first portion of the multifunctional openings is connected to a first multifunctional channel fluid, and a second portion of the multifunctional openings is connected to a second multifunctional channel fluid.

12. The substrate support of claim 11, wherein a third portion of the multifunctional opening is in fluid communication with a third multifunctional channel.

13. A substrate support according to claim 12, wherein the first multifunctional channel, the second multifunctional channel and the third multifunctional channel are cavities within the substrate support, the cavities extending around a portion of the substrate support in the circumferential direction, and / or wherein each of the first multifunctional channel, the second multifunctional channel and the third multifunctional channel is directly connected to a fluid management system so that the gas flow supplied to each of the first multifunctional channel, the second multifunctional channel and the third multifunctional channel can be individually controlled.

14. A lithographic apparatus comprising the substrate support according to any one of claims 1 to 13.

15. A method of loading a substrate onto a substrate support, the substrate support having a first circumferential wall, a second circumferential wall radially outward of the first circumferential wall, a third circumferential wall radially outward of the second circumferential wall, and a fourth circumferential wall radially outward of the third circumferential wall, wherein a first region is between the first circumferential wall and the second circumferential wall, a second region is between the second circumferential wall and the third circumferential wall, and a third region is between the third circumferential wall and the fourth circumferential wall, the method comprising: a substrate loading step, wherein a gas is supplied to the first region; A substrate clamping step wherein the gas is drawn from the first region and the fluid is drawn from the third region.

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