Substrate holder for use in lithographic apparatus

Abstract

The present disclosure provides a substrate holder for use in a lithographic apparatus configured to support a substrate, comprising: a body having a body surface; a plurality of first support elements protruding from the body surface, the first support elements supporting the substrate having a first height; a sealing unit including a first sealing member having an upper surface and a second height and positioned radially outward of and around the plurality of first support elements; and a plurality of second support elements positioned radially outward of the first sealing member, where the second support elements have a distal surface configured to support a substrate and a first height. The plurality of first support elements, the first sealing member, or the plurality of second support elements includes a coating made of diamond-like carbon, diamond, silicon carbide, boron nitrite, or boron nitride carbon, and the coating forms distal end surfaces of the plurality of support elements and / or forms an upper surface of the first sealing member. A lithographic apparatus is also disclosed.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of European Application No. 17206912.2 filed on December 13, 2017 and European Application No. 18183119.9 filed on July 12, 2018. These two European applications are incorporated herein by reference in their entireties. Technical field

[0003] The present disclosure relates to a substrate holder for a lithographic apparatus. Background art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern onto a substrate. For example, a lithographic apparatus can be used to manufacture integrated circuits (ICs). For example, a lithographic apparatus can project a pattern of a patterning device (e.g., a mask), often also referred to as a "design layout" or "design", onto a layer of radiation - sensitive material (resist) disposed on a substrate (e.g., a wafer).

[0005] With the continuous progress of the semiconductor manufacturing process, the size of circuit elements has been continuously reduced, and the number of functional elements (such as transistors) per device has been steadily increasing for decades, following a trend commonly known as "Moore's Law". To keep up with Moore's Law, the semiconductor industry has been pursuing technologies capable of creating smaller and smaller features. To project a pattern onto a substrate, a lithographic apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features patterned on the substrate. Currently, typical wavelengths used are 365 nanometers (i - line), 248 nanometers, 193 nanometers, and 13.5 nanometers. Compared with a lithographic apparatus using radiation with a wavelength of, for example, 193 nm, a lithographic apparatus using extreme ultraviolet (EUV) radiation with a wavelength in the range of 4 nm to 20 nm (such as 6.7 nm or 13.5 nm) can be used to form smaller features on a substrate.

[0006] In an immersion lithographic apparatus, an immersion liquid is inserted into the space between the substrate and the projection system of the apparatus. The path of this immersion liquid can reach the lower surface of the substrate from the edge of the substrate. This can be harmful, because this immersion liquid contaminates the lower surface of the substrate, and / or because of the heat load applied to the lower surface of the substrate at a position near the edge of the substrate due to the evaporation of the immersion liquid. The substrate holder configured to support the substrate can have features that reduce the amount and / or distance of the inward radial movement of the immersion liquid along the lower surface of the substrate.

[0007] Typically, when the substrate is irradiated, the substrate will be supported by a substrate holder. The substrate holder may include specific parts, such as support elements, which contact the underside of the substrate during use to support the substrate. After the substrate has been irradiated, it can be removed from the substrate holder. Specific steps can be performed to unload the substrate from the substrate holder. During the unloading process, the substrate may be deformed. This deformation typically causes the center of the substrate to rise away from the substrate holder, causing the substrate to hang downward in a cantilever manner towards the substrate holder above the outermost holder below the substrate.

[0008] During the unloading process, the deformed substrate may contact different parts of the substrate holder and wear against different parts of the substrate holder, which may cause various problems. First, during unloading, the interaction between the support element of the substrate holder and the underside of the substrate causes wear of the support element. Since the support element is used to support the substrate for irradiating additional layers or supporting additional substrates, any wear of the support element may cause focusing and / or overlay problems. Any wear of the support element may mean that the substrate stage needs to be replaced at the appropriate time. In other words, the wear of the support element may limit the service life of the substrate holder. Second, the underside of the substrate tends to contact features used to reduce the amount and / or distance of immersion liquid moving radially inward from the outer edge. This means that the substrate will wear the features, and the features will scratch against the underside of the substrate located at the outer edge of the substrate. This generates particles that contaminate the system and causes focusing and / or overlay problems. Summary of the Invention

[0009] An object of the present invention is to provide a substrate holder that reduces wear on the support elements for supporting the substrate and / or reduces damage to the underside of the substrate that may contaminate the system.

[0010] In an embodiment of the present invention, there is provided a substrate holder for use in a lithographic apparatus and configured to support a substrate, the substrate holder comprising: a body having a body surface; a plurality of support elements protruding from the body surface, wherein each support element has a distal end face configured to support the substrate and a first height; a sealing unit including a first sealing member protruding from the body surface, the first sealing member having an upper surface and a second height less than the first height and positioned radially outside the plurality of support elements and surrounding the plurality of support elements, the upper surface having a contact area configured to contact the substrate during substrate loading and / or unloading; and, the position of the contact area is arranged at a sufficient distance from the plurality of support elements such that during substrate loading and / or unloading, the force applied by the substrate to the first sealing member is greater than the force applied by the substrate to the plurality of support elements.

[0011] In an embodiment of the present invention, a substrate holder for use in a lithographic apparatus and configured to support a substrate is provided. The substrate holder includes: a body having a body surface; a plurality of support elements protruding from the body surface, each support element having a distal end face configured to support the substrate and a first height; a sealing unit including a first sealing member protruding from the body surface, the first sealing member having a second height less than the first height and being positioned radially outward of and surrounding the plurality of support elements, the upper surface having a contact area configured to contact the substrate during substrate loading and / or unloading; at least one additional member protruding from the body surface and having an upper surface and a third height less than the first height, the at least one additional member being radially outward of the sealing unit and surrounding the plurality of support elements, the at least one additional member including a coating forming the upper surface of the additional member, the coating having a contact area configured to contact the substrate during substrate loading and / or unloading, the coating having a contact area configured to contact the substrate during substrate loading and / or unloading, wherein the coating is made of diamond-like carbon (such as a-CH), diamond, silicon carbide (such as SiSiC or SiC), boron nitride, or boron carbon nitride (BCN); and wherein the position of the contact area of the additional member is arranged at a sufficient distance from the plurality of support elements such that during substrate loading and / or unloading, the force applied by the substrate to the additional member is greater than the force applied by the substrate to the plurality of support elements.

[0012] In an embodiment of the present invention, a substrate holder for use in a lithographic apparatus and configured to support a substrate is provided. The substrate holder includes: a body having a body surface; a plurality of support elements protruding from the body surface, each support element having a distal end face configured to support the substrate and a first height; a sealing unit including a first sealing member protruding from the body surface, the first sealing member having an upper surface and a second height less than the first height and being positioned radially external to and surrounding the plurality of support elements, and the upper surface having a contact area configured to contact the substrate during substrate loading and / or unloading, and wherein in a cross-section passing radially through the first sealing member, the profile of the contact area has a shape configured such that during substrate loading and / or unloading, the substrate contacts the first sealing member via at least two different points of the profile.

[0013] In an embodiment of the present invention, a lithographic apparatus is provided, the lithographic apparatus including a substrate holder configured to support a substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments of the present invention will now be described, by way of example only, with reference to the schematic drawings, in which:

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

[0016] - Figure 2A and 2B depicts two different versions of a fluid handling structure in cross-section, with different features shown on the left and right, which may extend around the entire circumference;

[0017] - Figure 3A depicts a substrate holder according to the prior art in cross-section, Figure 3B depicts Figure 3A an enlarged portion of, showing the outermost support elements and sealing members;

[0018] - Figure 4 depicts the edge of a substrate holder according to the present invention in cross-section;

[0019] - Figure 5 depicts the edge of a substrate holder according to the present invention in cross-section;

[0020] - Figure 6A and 6B depicts the edge of a substrate holder according to the present invention in cross-section;

[0021] - Figures 7A - 7G each depict a sealing unit according to the present invention in cross-section;

[0022] - Figure 8 depicts the edge of a substrate holder according to the present invention in cross-section;

[0023] - Figure 9 depicts the edge of a substrate holder according to the present invention in cross-section; and

[0024] - Figure 10 depicts the edge of a substrate according to the present invention in cross-section. DETAILED DESCRIPTION

[0025] In this document, the terms "radiation" and "beam" are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., having a wavelength of 365, 248, 193, 157, or 126 nm).

[0026] As used herein, the terms "reticle", "mask", or "patterning device" may be broadly interpreted as referring to a general patterning device that can be used to endow an incident radiation beam with a patterned cross-section corresponding to a pattern to be created in a target portion of a substrate. The term "light valve" may also be used in this context. Examples of such other patterning devices include programmable mirror arrays and programmable LCD arrays in addition to classical masks (transmission or reflection masks, binary masks, phase-shift masks, hybrid masks, etc.).

[0027] Figure 1 A lithographic apparatus is schematically depicted. The lithographic apparatus includes: an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam B (e.g., UV radiation or DUV radiation); a mask support (e.g., a mask table) MT configured to support a patterning device (e.g., a mask) MA and connected to a first positioning device PM configured to accurately position the patterning device MA according to certain parameters; a substrate support (e.g., a wafer table) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioning device PW configured to accurately position the substrate support WT according to certain parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project the pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., a target portion including one or more dies) of the substrate W.

[0028] In operation, the illumination system IL receives the radiation beam B from a radiation source SO, for example via a beam delivery system BD. The illumination system IL may include various types of optical components for directing, shaping, and / or controlling the radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical elements, or any combination thereof. The illuminator IL can be used to condition the radiation beam B to have a desired spatial and angular intensity distribution in a plane of the patterning device MA in its cross-section.

[0029] As used herein, the term "projection system" PS should be broadly interpreted as encompassing various types of projection systems, including refractive, reflective, refractive-reflective, anamorphic, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, depending on the exposure radiation used, and / or other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" PS.

[0030] A lithographic apparatus may be of the type in which at least a portion of a substrate is covered by an immersion liquid (e.g., water) having a relatively high refractive index to fill a space 11 between a projection system PS and the substrate W, which is also referred to as immersion lithography. More information on immersion techniques is given in US6,952,253, which is incorporated herein by reference.

[0031] The lithographic apparatus may also be of the type having two or more substrate supports WT (also known as "dual stage"). In such a "multi-stage" machine, the substrate supports WT can be used in parallel, and / or steps of preparing a substrate W for a subsequent exposure of the substrate W located on one of the substrate supports WT can be carried out while another substrate W on another substrate support WT is being used for exposing a pattern on the other substrate W.

[0032] In addition to the substrate support WT, the lithographic apparatus may include a metrology stage. The metrology stage is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure properties of the projection system PS or the radiation beam B. The metrology stage may hold a plurality of sensors. The cleaning device may be arranged to clean a part of the lithographic apparatus, such as a part of the projection system PS or a part of the system providing the immersion liquid. The metrology stage may move under the projection system PS when the substrate support WT is moved away from the projection system PS.

[0033] In operation, a radiation beam B is incident on a patterning device (e.g., a mask MA) held on a mask support MT and is patterned by a pattern (design layout) present on the patterning device MA. After traversing the entire mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. By means of a second positioning device PW and a position measurement system IF, the substrate support WT can be accurately moved, for example, to position different target portions C in the path of the radiation beam B in a focused and aligned position. Similarly, a first positioning device PM and possibly another position sensor (which is not explicitly depicted in Figure 1 are used to accurately position the patterning device MA relative to the path of the radiation beam B. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 can be used to align the patterning device MA and the substrate W. Although the substrate alignment marks P1, P2 as illustrated occupy dedicated target portions, the substrate alignment marks P1, P2 may be located in the space between the target portions. When the substrate alignment marks P1, P2 are located between the target portions C, the substrate alignment marks P1, P2 are referred to as scribe alignment marks.

[0034] To clearly illustrate the present invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes, namely, the x-axis, the y-axis, and the z-axis. Each of the three axes is orthogonal to the other two axes. A rotation about the x-axis is referred to as an Rx rotation. A rotation about the y-axis is referred to as an Ry rotation. A rotation about the z-axis is referred to as an Rz rotation. The x-axis and the y-axis define a horizontal plane, while the z-axis is in the vertical direction. The Cartesian coordinate system does not limit the present invention, but is only used for illustration. Alternatively, 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, such that the z-axis has a component along the horizontal plane.

[0035] Immersion techniques have been introduced into lithography systems to enable improved resolution of smaller features. In an immersion lithography apparatus, a liquid layer of an immersion liquid having a relatively high refractive index is interposed in the space 11 between the projection system of the apparatus (through which a patterned beam is projected onto a substrate W) and the substrate W. The immersion liquid covers at least a portion of the substrate under the final element of the projection system PS. Thus, at least a portion of the substrate W undergoing exposure is immersed in the immersion liquid. The effect of the immersion liquid is to enable imaging of smaller features because the wavelength of the exposure radiation in the liquid is shorter than in a gas. (The effect of the immersion liquid can also be regarded as increasing the effective numerical aperture (NA) of the system and also increasing the depth of focus.)

[0036] In commercial immersion lithography, the immersion liquid is water. Generally, the water is highly purified distilled water, such as ultrapure water (UPW) commonly used in semiconductor fabrication plants. In an immersion system, the UPW is often purified and can undergo additional processing steps before being supplied as the immersion liquid to the immersion space 11. In addition to water being usable as the immersion liquid, other liquids having a high refractive index can also be used, for example: hydrocarbons (such as fluorocarbons); and / or aqueous solutions. Furthermore, it has been envisioned to use other fluids than liquids for immersion lithography.

[0037] In this specification, localized immersion will be mentioned in the description, where the immersion liquid is restricted in use to the space 11 between the final element and the surface facing the final element. The facing surface is the surface of the substrate W, or the surface of a support platform (or substrate support WT) coplanar with the surface of the substrate W. (Note that hereinafter the surface of the substrate W also refers additionally or alternatively to the surface of the substrate support, unless otherwise explicitly stated, and vice versa). The fluid handling structure 12 between the projection system PS and the substrate support WT serves to confine the immersion liquid to the immersion space 11. The space 11 filled with the immersion liquid is smaller in area than the top surface of the substrate W, and the space 11 remains substantially stationary relative to the projection system PS while the substrate W and the substrate support WT move below.

[0038] Other immersion systems have been envisioned, such as non - restrictive immersion systems (so - called "fully wet" immersion systems) and bath immersion systems. In a non - restrictive immersion system, the immersion liquid covers an area larger than the surface under the final element. The liquid outside the immersion space 11 exists as a thin liquid film. The liquid can cover the entire surface of the substrate W, or even the substrate W and the substrate support WT coplanar with the substrate W. In a bath - type system, the substrate W is completely immersed in a bath of immersion liquid.

[0039] The fluid handling structure 12 is a structure that supplies immersion liquid to the immersion space 11, removes immersion liquid from the space 11, and thus confines the immersion liquid to the immersion space 11. It includes features of parts of a fluid supply system. The arrangement disclosed in the PCT patent application with publication number WO99 / 49504 is an earlier fluid handling structure that includes pipes that supply immersion liquid to the space 11 or recover immersion liquid from the space 11, and operates relying on the relative movement of the platform under the projection system PS. In the latest design, the fluid handling structure extends along at least a part of the boundary of the space 11 between the final element of the projection system PS and the substrate support WT or the substrate W, so as to partially define the space 11.

[0040] The fluid handling structure 12 can have a series of different functions. Each function can originate from corresponding features that enable the fluid handling structure 12 to achieve the function. The fluid handling structure 12 can be referred to by many different terms, each term referring to a function, such as a barrier member, a sealing unit, a fluid supply system, a fluid removal system, a liquid confinement structure, and so on.

[0041] As a barrier member, the fluid handling structure 12 is a barrier to the flow of immersion liquid from the space 11. As a liquid confinement structure, the structure confines the immersion liquid to the space 11. As a sealing unit, the sealing features of the fluid handling structure form a seal to confine the immersion liquid to the space 11. The sealing features can include an additional gas flow through an opening in the surface of a sealing member (such as an air knife) from the sealing unit.

[0042] In one embodiment, the fluid handling structure 12 can supply immersion fluid and thus is a fluid supply system.

[0043] In one embodiment, the fluid handling structure 12 can at least partially confine the immersion fluid and thus is a fluid confinement system.

[0044] In one embodiment, the fluid handling structure 12 can provide a barrier to the immersion fluid and thus is a barrier member, such as a fluid confinement structure.

[0045] In one embodiment, the fluid handling structure 12 may create or use a gas flow, for example to help control the flow and / or position of the immersion fluid.

[0046] The gas flow may form a seal to confine the immersion fluid, and thus, the fluid handling structure 12 may be referred to as a sealing unit; this sealing unit may be a fluid confinement structure.

[0047] In one embodiment, an immersion liquid is used as the immersion fluid. In this case, the fluid handling structure 12 may be a liquid delivery system. In the context of the foregoing description, references in this paragraph to features defined relative to the fluid may be understood to include features defined relative to the liquid.

[0048] A lithographic apparatus has a projection system PS. During exposure of a substrate W, the projection system PS projects a patterned radiation beam onto the substrate W. In order to reach the substrate W, the path of the radiation beam B passes through an immersion liquid from the projection system PS, which is confined by a fluid handling structure 12 located between the projection system PS and the substrate W. The projection system PS has a lens element that contacts the immersion liquid and is the last element in the path of the beam. This lens element that contacts the immersion liquid may be referred to as the "last lens element" or "final element". The final element is at least partially surrounded by the fluid handling structure 12. The fluid handling structure 12 may confine the immersion liquid below the final element and above the facing surface.

[0049] Figure 2A and 2B show different features that may be present in variants of the fluid handling structure 12. Unless described otherwise, designs may share some of the features with Figure 2A and 2B the same features. The features described herein may be selected individually or in combination as shown or as required.

[0050] Figure 2AShows a fluid handling structure 12 surrounding the bottom surface of a final element 100. The final element 100 has an inverted frustoconical shape. The frustoconical shape has a flat bottom surface and a conical surface. The frustoconical shape projects from the flat surface and has a flat bottom surface. The flat bottom surface is the optically active portion of the bottom surface of the final element 100 through which the radiation beam B can pass. The final element 100 may have a coating 30. The fluid handling structure 12 surrounds at least part of the frustoconical shape. The fluid handling structure 12 has an inner surface that faces the conical surface of the frustoconical shape. The inner surface and the conical surface have complementary shapes. The top surface of the fluid handling structure 12 is substantially flat. The fluid handling structure 12 can be assembled around the frustoconical shape of the final element 100. The bottom surface of the fluid handling structure 12 is substantially flat, and in use, the bottom surface can be parallel to the facing surface of the substrate support WT and / or the substrate W. The distance between the bottom surface and the facing surface can be in the range of 30 to 500 microns, desirably in the range of 80 to 200 microns.

[0051] Compared to the final element 100, the fluid handling structure 12 extends closer to the facing surface of the substrate W and the substrate support WT. Thus, a space 11 is defined between the inner surface of the fluid handling structure 12, the flat surface of the frustoconical portion, and the facing surface. During use, the space 11 is filled with an immersion liquid. The immersion liquid fills at least part of the buffer space between the complementary surfaces between the final element 100 and the fluid handling structure 12, and in one embodiment, fills at least part of the space between the complementary inner surface and the conical surface.

[0052] The immersion liquid is supplied to the space 11 through an opening formed in the surface of the fluid handling structure 12. The immersion liquid can be supplied through a supply opening 20 in the inner surface of the fluid handling structure 12. Alternatively or additionally, the immersion liquid is supplied from a lower supply opening 23 formed in the lower surface of the fluid handling structure 12. The lower supply opening 23 can surround the path of the radiation beam B, and it can be formed by a series of openings in an array. The immersion liquid is supplied to fill the space 11 such that the flow through the space 11 under the projection system PS is laminar. Additionally, supplying the immersion liquid from the lower supply opening 23 below the fluid handling structure 12 also prevents air bubbles from entering the space 11. This supply of the immersion liquid acts as a liquid seal.

[0053] The immersion liquid can be recovered from a recovery opening 21 formed in the inner surface. The recovery of the immersion liquid through the recovery opening 21 can be achieved by applying a negative pressure; the recovery through the recovery opening 21 is the result of the speed at which the immersion liquid flows through the space 11; or the recovery can be the result of both. When viewed in a plan view, the recovery opening 21 can be located on the opposite side of the supply opening 20. Additionally or alternatively, the immersion liquid can be recovered through an overflow opening 24 located on the top surface of the fluid handling structure 12. In one embodiment, the supply and recovery openings 20, 21 can swap their functions (i.e., the flow direction of the liquid is reversed). This allows the flow direction to be changed according to the relative movement of the fluid handling structure 12 and the substrate W.

[0054] Additionally or alternatively, the immersion liquid can be recovered from below the fluid handling structure 12 through a recovery opening 25 formed in the bottom surface of the fluid handling structure 12. The recovery opening 25 can be used to hold (or "pin") the meniscus 33 of the immersion liquid to the fluid handling structure 12. The meniscus 33 is formed between the fluid handling structure 12 and the facing surface, and the meniscus 33 serves as a boundary between the liquid space and the gas external environment. The recovery opening 25 can be a perforated plate, and the perforated plate can recover the immersion liquid in a single-phase flow. The recovery opening in the bottom surface can be a series of pinning openings 32, and the immersion liquid is recovered through the pinning openings 32. The pinning openings 32 can recover the immersion liquid of a two-phase fluid.

[0055] Optionally, the air knife opening 26 is radially outward with respect to the inner surface of the fluid handling structure 12. Gas can be supplied through the air knife opening 26 at an increased speed to assist in confining the immersion liquid to the space 11. The supplied gas can be humidified and can substantially contain carbon dioxide. The gas recovery opening 28 for recovering the gas supplied through the air knife opening 26 is radially outward from the air knife opening 26. There can be additional openings in the bottom surface of the fluid handling structure 12 that are open to the atmosphere or a gas source. For example, additional openings can be present between the air knife opening 26 and the gas recovery opening 28, and / or between the pinning openings 32 and the air knife opening 26.

[0056] Figure 2B The features shown in Figure 2A common are shared with the same reference numerals. The fluid handling structure 12 has an inner surface that is complementary to the conical surface of the frustoconical shape. The lower surface of the fluid handling structure 12 is closer to the facing surface than the bottom flat surface of the frustoconical shape.

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

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

[0059] The inner perimeter 39 of the lower surface of the fluid handling structure 12 extends away from the inner surface and into the space 11 to form a plate 40. The inner perimeter 39 forms small holes, the size of which can be set to match the shape and size of the radiation beam B. The plate 40 can be used to isolate the immersion liquid on both sides thereof. The supplied immersion liquid flows inwardly towards the holes, through the inner holes, and then radially outwardly below the plate 40 towards the periphery of the recovery opening 25.

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

[0061] In Figure 2A and 2B examples, multiple recovery openings (e.g., Figure 2A the recovery opening 21 in Figure 2A and 2B both the overflow recovery members 24 in Figure 2A and 2B both the recovery openings 25 in Figure 2A the pinning opening 32 in Figure 2B and Figure 2A the supply opening 20 in Figure 2Athe lower supply opening 23 therein, and Figure 2B at least one of the supply openings 34 therein) can be used to control the amount of the immersion liquid in the space 11. The position of the meniscus 33 and the position of the meniscus 22 will vary according to the amount of the immersion liquid in the space 11. The meniscus 22 is similar to the meniscus 33, except that it is formed between another part of the fluid delivery system 12 and the final element 100.

[0062] The substrate support WT may include a substrate holder 200 configured to support the substrate W. Figure 3A The substrate holder 200 and an associated substrate W supported by the substrate holder 200 are illustrated in cross-section. The substrate holder 200 includes a body 201 having a body surface 202. In use, the body surface 202 faces the lower surface of the substrate W, i.e., the lower surface of the substrate W facing the substrate holder 200.

[0063] In a central region of the body surface 202, a plurality of support elements 210 project from the body surface 202. Each support element 210 has a distal end face 211 (as Figure 3B shown), and the distal end face 211 is configured to support the substrate W. For example, during irradiation of the substrate W, the support elements 210 can be configured to contact the lower surface of the substrate W. The support elements 210 are arranged in a pattern relative to each other in a plan view. The pattern is for supporting the substrate W and reducing any bending of the substrate W towards the body surface 202 to an acceptable amount.

[0064] Compared with the planar area of the substrate W, the planar area of each support element 210 is relatively small. Therefore, the support elements 210 only contact a small area of the lower surface of the substrate W. This reduces the chance of contaminants transferring from the substrate holder 200 to the substrate W.

[0065] A pressure difference is established across the entire substrate W. For example, the space between the body 201 of the substrate holder 200 and the substrate W is connected to a negative pressure that is lower than the higher pressure above the substrate W. When in use, for example when the substrate W is irradiated, the pressure difference generates a force to hold the substrate W to the substrate holder 200. In other words, the substrate holder 200 has a member for clamping the substrate W to the substrate holder 200.

[0066] In an immersion lithography apparatus, liquid will be present near the edge of the substrate W at least at certain times during the exposure of the substrate W. Due to the negative pressure between the body 201 of the substrate holder 200 and the lower surface of the substrate W, this liquid will be sucked around the edge of the substrate W and under the substrate W. To reduce the occurrence of contact between the liquid and the lower surface of the substrate W, and in particular the contact occurring in the region where the support element 210 contacts the substrate W, a sealing unit may be provided, which sealing unit includes at least one member protruding from the body surface 202 of the body 201. Generally speaking, the liquid between the substrate W and the body surface 202 passes radially inward through the sealing unit. The sealing unit may include a first sealing member and a second sealing member. The first sealing member may be radially outward of and surround the second sealing member. The first sealing member may be used to reduce the pressure in the region between the first sealing member and the second sealing member. The second sealing member may be configured to restrict or prevent the liquid from flowing or passing radially inward through the second sealing member. The first sealing member may also at least partially restrict the liquid from passing radially inward through the first sealing member. The sealing unit may be configured to restrict the passage of liquid around substantially the entire circumference of the sealing unit (i.e., around the entire substrate W). In other words, due to the presence of the sealing unit, the amount of liquid at a position radially outward of the sealing unit is restricted or prevented from moving radially inward to a position radially inward of the sealing unit. This means that the presence of the sealing unit reduces the amount of liquid at the position radially inward of the sealing unit compared to the case where no sealing device is provided. It is possible to prevent the liquid from simply bypassing the sealing unit.

[0067] The sealing unit may be part of a sealing mechanism, such as a seal formed adjacent to or around the radial outer edge of the substrate W. The sealing unit may include additional components for restricting the radial inward passage of liquid.

[0068] One purpose of the sealing unit is to restrict the radially inward gas flow (which may undesirably be moist) towards the support element 210. This enables a negative pressure to be generated around the support element 210, which is necessary for clamping the substrate W to the substrate holder 200. It is advantageous to allow some gas to flow over the sealing unit so that when the negative pressure source that generates the negative pressure around the support element 210 is turned off, the substrate W can be quickly removed from the substrate holder 200. If the gas flow rate through the sealing unit is too low, the pressure around the support element 210 balances or equals the pressure above the substrate W, resulting in too much time being used to release the substrate W. The substrate holder 200 may be configured to generate an overpressure below the lower surface of the substrate W so that the substrate W can be removed more quickly.

[0069] The sealing unit may include at least one sealing element. The sealing element may include a first sealing member 220 and a second sealing member 240. The first sealing member 220 is as Figure 3Aand 3B As shown. The second sealing member 240 will be described in further detail below. The first sealing member 220 can be configured to restrict the flow of gas / fluid radially inward of the first sealing member 220. For example, in a dry lithography system, the sealing unit may include only the first sealing member 220.

[0070] The first sealing member 220 has an upper surface 221, which is the distal end of the first sealing member 220. Thus, the upper surface 221 is positioned away from the contact point between the first sealing member 220 and the main body surface 202 (even if the first sealing member 220 and the main body 201 are integrally formed with each other). In use, the upper surface 221 is configured to form a gap between the upper surface 221 and the lower surface of the substrate W, that is, the upper surface 221 is configured to be slightly closer to the main body surface 202 than the distal end face 211 of the support element 210. This is advantageous because this arrangement allows gas to be sucked above the first sealing member 220 (below the substrate W) just before the substrate W is removed, while allowing restriction of the passage of liquid in the same direction. This is achieved without contacting a large area of the lower surface of the substrate W, and contacting a large area of the lower surface of the substrate W would detrimentally cause contaminants to transfer from the first sealing member 220 to the substrate W. This would also make it more problematic to remove the substrate W from the substrate holder 200.

[0071] As Figure 3A and Figure 3B shown, the outermost radially of the plurality of support elements 210 is some distance away from the edge of the substrate W. In the absence of any other features to support the substrate W radially outward of the outermost radially support element 210, the edge of the substrate W may bend downward, especially during the unloading process of the substrate W. This is due to the negative pressure below the substrate W compared to above the substrate W.

[0072] In use, a negative pressure can be provided in the central region of the substrate holder 200 between the main body surface 202 and the substrate W. This negative pressure is the reason why the substrate W can be clamped to the substrate holder 200 during use. This clamping negative pressure may have a lower magnitude (i.e., a less stringent vacuum) compared to the negative pressure in the radially outward region of the support element 210.

[0073] During the unloading of the substrate W, the pressure between the main body surface 202 and the substrate W can be controlled to allow unloading of the substrate W. The unloading of the substrate W can include the step of increasing the pressure between the main body surface 202 and the substrate W. This is achieved by Figure 3Ais indicated by the upward arrow. For example, when the substrate W is to be unloaded, the vacuum under the substrate W can be removed by injecting high-pressure air under the substrate W. Thus, unloading of the substrate W includes at least one release step, for example, increasing the pressure between the main body 201 and the lower surface of the substrate W. The advantage of generating an overpressure under the substrate W during unloading is that any fluid between the substrate W and the main body surface 202 will be pushed radially outwards. However, this typically results in an overpressure being generated under the center of the substrate W and a negative pressure being generated around the edge of the substrate W. Thus, the substrate W may be deformed and bulge upwards in the middle of the substrate W, and extend downwards as a cantilever at the edge of the substrate W.

[0074] Figure 3A and 3B represents the prior art and shows that when the substrate W bulges upwards in the middle thereof, the side edges of the substrate W will scrape past the radially outermost support element 210 and the first seal member 220. As Figure 3B shown in the enlargement in, there is an interaction between the distal end face 211 of the radially outermost support element 210 and the substrate W, and between the upper surface 221 of the first seal member 220 and the substrate W. As indicated above, this can have an adverse effect on the system.

[0075] Scraping of the substrate W over the distal end face 211 of the support element 210 will apply a force to the support element 210. Any interaction between the substrate W and one of the support elements 210 can result in wear on the support element 210. This is a problem because it can change the exact height of the support element 210. If the height of the support element 210 is changed, this may result in focusing and / or coverage problems when irradiating another substrate W and / or another layer of the same substrate W. If the support element 210 becomes too damaged, it may be necessary to replace the substrate holder 200. Thus, preventing damage to the support element 210 provides more stable long-term performance of the substrate holder 200.

[0076] When the lower surface of the substrate W scrapes past the edge of the first sealing member 220, an interaction occurs between the substrate W and the first sealing member 220, i.e., in a known system, the lower surface of the substrate W contacts the first sealing member 220 via a single-point contact (in cross-section) during unloading. This results in high stress points on the lower surface of the substrate W and also results in scratches on the lower surface of the substrate W. The scratches can generate particles of the substrate W or even the first sealing member 220, and these particles can contaminate the system. These particles are typically close to the edge of the substrate W and may thus end up on the top of the substrate W. Additionally, the interaction can cause wear of the first sealing member 220 in an undesirable manner, i.e., in a way that affects the ability of the first sealing member 220 (and thus the entire sealing unit) to perform its desired function. Thus, it is desirable to reduce the interaction between the first sealing member 220 and the substrate W in a way that may affect the ability of the first sealing member 220 to control the pressure between the first sealing member 220 and the second sealing member 240 and / or control the inward movement of liquid through the first sealing member 220. Therefore, preventing damage to the first sealing member 220 in certain areas used for providing the seal will provide a more stable long-term performance of the substrate holder 200.

[0077] Wear is harmful because it can lead to contamination of the substrate W and a change in the clamping characteristics of the substrate holder 200, and thus to deformation of the substrate W. The presence of liquid between the support element 210 and the lower side of the substrate W can also cause wear (if the substrate holder 200 is ceramic), and may cause a change in friction. Deformation of the substrate W can lead to imaging errors (such as overlay errors and / or focus errors), and contamination can also lead to imaging errors. The presence of liquid on the lower side of the substrate W is generally harmful because it may cause problems with the thermal stability of the substrate W or difficulties when droplets are lost during unloading of the substrate W.

[0078] Similar problems can occur during loading of the substrate W onto the substrate holder 200. Thus, during loading, the substrate W can be deformed in such a way that it causes the substrate W to scrape the substrate holder 200 as described above. Additionally or alternatively, during loading of the substrate W in a dry lithography apparatus, the substrate W can tilt during loading, which can cause the edge of the substrate W to contact the edge of the support element 210, thus causing wear.

[0079] As will be described below, the substrate holder 200 of the present invention eliminates some of these difficulties due to the position and shape of the first sealing member 220, which is configured to interact with the substrate W during unloading (or loading) of the substrate W while still providing a mechanism as part of a sealing unit (e.g., by restricting fluid / gas from passing radially inwards through the first sealing member 220). Additionally, the unloading step may be referred to as a release step, and thus, the term "release" may be used interchangeably in the following parts of the description regarding the unloading of the substrate W.

[0080] In the present invention, a substrate holder 200 as Figure 3A and 3B described is provided. However, the first sealing member 220 is configured to address some of the above problems. The differences between the present invention and at least the first sealing member 220 as Figure 3A and 3B described above will be described in detail below.

[0081] More specifically, the present invention provides a substrate holder 200 for a lithographic apparatus, which is configured to support a substrate W. The substrate holder 200 includes a body 201 having a body surface 202. The substrate holder 200 further includes a plurality of support elements 210 protruding from the body surface 202, wherein each support element 210 has a distal end face 211 configured to support the substrate W. The support elements 210 may have a first height. The substrate holder 200 further includes a sealing unit. The sealing unit may be configured to restrict liquid between the substrate W and the body surface 202 from passing radially inwards through the sealing unit. The sealing unit may include a first sealing member 220 protruding from the body surface 202 and having an upper surface 221. The first sealing member 220 may have a second height, which is less than the first height. Thus, the support elements 210 may be higher than the first sealing member 220. Similarly, the support elements 210 may be higher than the second sealing member 240 (if provided). The sealing unit may include a second sealing member 240 protruding from the body surface 202. The second sealing member 240 may be located radially inwards of the first sealing member 220. The first sealing member 220 may be located radially outwards of the plurality of support elements 210 and surround the plurality of support elements 210. The second sealing member 240 is optional and may be particularly beneficial for immersion systems to prevent liquid from passing radially inwards.

[0082] The first sealing member 220 and the second sealing member 240 can be configured together to restrict or prevent the radial inward passage of liquids and gases through the sealing unit. The first sealing member 220 can be configured to form a low-pressure region between the first sealing member 220 and the second sealing member 240. Thus, the pressure in the space (i.e., the sealing region) between the first sealing member 220 and the second sealing member 240 can be lower than the pressure around the sealing unit. The low-pressure region between the first sealing member 220 and the second sealing member 240 reduces the amount of liquid moving radially inward in the space between the first sealing member 220 and the second sealing member 240.

[0083] The first sealing member 220 can be configured to provide a radially inward pressure drop of the first sealing member 220 relative to the pressure in the radially outward region of the sealing unit. For example, the first sealing member 220 can be mainly used to form a pressure drop from the ambient environment to about -500 mbar, and thus form a vacuum for clamping the substrate W. The second sealing member 240 can be used to maintain a pressure difference of about 25 mbar between the inside of the substrate holder 200 and the sealing region, for example, -475 mbar. This small pressure difference may cause the generation of a water body (capillary) in the small gap between the second sealing member 240 and the substrate W. The main function of the second sealing member 240 can be to restrict the further inward movement of water. The second sealing member 240 can be configured to reduce or prevent the radial inward passage of liquid into the interior of the sealing unit.

[0084] In a plan view, the cross-sectional area of the first sealing member 220 may be much larger than the cross-sectional area of the support element 210. In a plan view, the relatively large area of the first sealing member 220 results in a greater resistance to the radial inward passage of liquid between the substrate W and the main body surface 202 through the first sealing member 220. The cross-sectional shape of the first sealing member 220 in a plan view can be circular, or more specifically, loop-shaped or annular. Thus, the first sealing member 220 can have an annular shape.

[0085] In a plan view, the cross-sectional area of the second sealing member 240 may be much larger than the cross-sectional area of the support element 210. In a plan view, the relatively large area of the second sealing member 240 results in a greater resistance to the radial inward passage of liquid between the substrate W and the main body surface 202 through the second sealing member 240. The first sealing member 220 and the second sealing member 240 can have similar or the same cross-sectional area. The cross-sectional shape of the second sealing member 240 in a plan view can be circular, or more specifically, loop-shaped or annular. Therefore, the second sealing member 240 can have an annular shape.

[0086] The first sealing member 220 may surround or encircle the plurality of support elements 210. Thus, the first sealing member 220 may generally surround the entire circumference of the plurality of support elements 210. In other words, for example, when viewed in a plan view, the first sealing member 220 may surround or enclose the plurality of support elements 210. The first sealing member 220 may be a continuous (although not necessarily uniform in cross-section) barrier member surrounding the support elements 210. Alternatively, the first sealing member 220 may be formed of a plurality of segments. The plurality of segments may substantially form an entire annular ring. In other words, the first sealing member 220 may be formed of a plurality of separate or individual segments that substantially form an annular ring. In a segmented annular ring, there may be a plurality of sealing member portions with gaps between each adjacent sealing member portion. The gaps between adjacent sealing member portions may be the same length as, or shorter than, either or both of the adjacent portions. The distance between each sealing member portion may be equal to, or smaller than, the width of either or both of the adjacent sealing member portions. At least one of the gaps between adjacent sealing member portions (i.e., the spacing between adjacent portions) may be on the order of tens or hundreds of micrometers. At least one of the gaps between adjacent sealing member portions may be approximately 10 micrometers narrow. At least one of the gaps may be between 0.5 and 5 mm. Some or all of the spacings may have these dimensions. Providing small gaps may be advantageous because any contaminants, such as those resulting from the interaction between the underside of the substrate W and the first sealing member 220, may be trapped in the gaps while still providing a relatively large contact area on the first sealing member 220.

[0087] The second sealing member 240 may be located radially inward of the first sealing member 220. The second sealing member 240 may be radially outward of some or all of the plurality of support elements 210. Some of the plurality of support elements 210 may be disposed radially outside the second sealing member 240. Thus, some of the plurality of support elements 210 may be disposed between the first sealing member 220 and the second sealing member 240. This will be described in further detail below with reference to Figure 10 Further details.

[0088] The second sealing member 240 may surround at least a portion (if not most) of the plurality of support elements 210. Thus, the second sealing member 240 may substantially surround the entire circumference of at least some (if not most) of the plurality of support elements 210. In other words, for example, when viewed in a plan view, the second sealing member 240 may enclose at least some (if not most) of the plurality of support elements 210. The second sealing member 240 may be a continuous (although not necessarily uniform in cross-section) barrier member surrounding the support element 210. Alternatively, the second sealing member 240 may be formed by a plurality of segments. The plurality of segments may substantially form an entire annular ring. In other words, the second sealing member 240 may be formed by a plurality of individual or separate segments that substantially form an annular ring. In a segmented annular ring, there may be a plurality of sealing member portions with a gap between each adjacent sealing member portion. The gap between adjacent sealing member portions may be the same length as or shorter than the length of either or both of the adjacent portions. The distance between each sealing member portion may be equal to the width of either or both of the adjacent sealing member portions, or smaller than the width of either or both of the adjacent sealing member portions. At least one of the gaps between adjacent sealing member portions (i.e., the gap between adjacent portions) may be on the order of tens or hundreds of micrometers. At least one of the gaps between adjacent sealing member portions may be approximately 10 micrometers narrow. At least one of the gaps may be between 0.5 and 5 mm. Some or all of the spacings may have these dimensions. Setting small gaps may be advantageous because any contaminants, such as from the interaction between the underside of the substrate W and the first sealing member 220, may be trapped in the gaps.

[0089] The upper surface 221 of the first sealing member 220 has a contact area 222 that is configured to contact the substrate W during unloading of the substrate W. The upper surface 221 of the first sealing member 220 is configured such that it does not contact the substrate W when the substrate W is irradiated, i.e., the first sealing member 220 is not used to support the substrate W during irradiation. The contact area 222 is configured such that it does not contact the substrate W when the substrate W is irradiated, i.e., the contact area 222 is not used to support the substrate W during irradiation. The contact area 222 may be configured to contact only the substrate W during unloading of the substrate W. In previously known systems, it was not anticipated that the upper surface of any of the provided sealing members would contact the substrate W during unloading (or loading) of the substrate W. Additionally, in previously known systems, there may not have been any contact between the sealing member and the substrate during loading or unloading, and thus all wear may have occurred on the support elements 210.

[0090] In the present invention, the position of the contact area 222 can be arranged at a sufficient distance from the plurality of support elements 210 such that during unloading of the substrate W, the force applied by the substrate W to the first sealing member 220 is greater than the force applied by the substrate W to the plurality of support elements 210. This means that during unloading of the substrate W, the wear of the support elements 210 is less than the wear of the first sealing member 220. This means that, compared with the wear of the first sealing member 220 when releasing the substrate using the configuration shown in Figure 3A and 3B , the wear of the support elements 210 can be reduced. Ideally, the first sealing member 220 can be the main feature that contacts the substrate W during unloading (i.e., ideally, at certain points during unloading), and the substrate W only contacts the contact surface 222 and does not contact the support elements 210.

[0091] In other words, the point and / or area of the first sealing member 220 configured to contact the substrate W during unloading of the substrate W is sufficiently far from the support elements 210 such that the wear on the radially outermost support element 210 is less than the wear on the first sealing member 220. For example, as shown in Figure 4 , if the first sealing member 220 has a uniform cross-section formed around the circumference, the cross-section shows a single-point contact, but this will be arranged around the circumference of the first sealing member 220, and the contact area 222 will be provided by an area around the entire first sealing member 220.

[0092] The contact area 222 can be merely the area of the first sealing member 220 configured to contact the substrate W at a certain point during the unloading process. This will generally be a known and defined area. For example, in Figure 4 , the contact area 222 is shown as the radially outermost point on the upper surface 221 of the first sealing member 220. The contact area 222 can be a point located between the upper surface 221 of the first sealing member 220 and the radially outer edge 223 of the first sealing member 220. In other words, the contact area 222 can provide an area between the upper surface 221 and the radially outer edge 223. Thus, the contact area 222 can form a connection between the upper surface 222 and the radially outer edge 223. This may be the point where the upper surface 221 and the radially outer edge 223 would otherwise meet, as shown in Figure 4 . Alternatively, the contact area 222 can be an area between these two surfaces, for example, as shown in Figure 6A . There can be a change in gradient between the upper surface 221 and the contact area 222. There can be a change in gradient between the surface of the radially outer edge 223 and the contact area 222.

[0093] The contact area 222 may not be uniform around the first sealing member 220 and may be configured to provide an increased contact area at certain locations where known particulate contaminants are greater.

[0094] As is well known, the first sealing member 220 should be disposed within a certain distance of the radially outermost support element 210 in order to maintain the required pressure between the substrate W and the body 201. Thus, the present invention teaches away from or contrary to this by providing a distance between the contact area 222 and the radially outer edge of the radially outermost support element 210 while simultaneously maintaining the required pressure.

[0095] The position of the contact area 222 relative to the support element 210 can be controlled in a variety of different ways. For example, as Figure 4 shown, the primary dimension relates to the distance between the radially outer edge 212 of the distal end face 211 of the radially outermost support element 210 and the outer upper edge of the upper surface 221 of the first sealing member 220. This dimension relates to these particular portions of the support element 210 and the first sealing member 220 because these particular portions are the portions of these components that will contact the lower surface of the substrate W during unloading of the substrate W.

[0096] This distance can be defined by the distance D in the radial direction. This distance can additionally or alternatively be defined by the distance y between the distal end face 211 of the support element 210 and the upper surface 221 of the first sealing member 220. Both of these distances will affect how the substrate W interacts with each of these components during the unloading process.

[0097] In this example, the contact area 222 is shown as an edge contact point in cross-section. Thus, in this embodiment, the contact area 222 is formed by the same contact points around the circumference of the first sealing member 220. This contact area 222 will be the same in Figure 4 as in the example shown in Figure 3A and 3B However, the position of the contact area 222 relative to the support element 210 in the present invention will be different from the relative position of the contact area of the prior art and will be configured to reduce wear of the support element 210 during unloading of the substrate W.

[0098] In one embodiment, the radial distance D from the radial outer edge 212 of the distal end face 211 to the contact region 222 is greater than 1000 microns, and preferably greater than 1500 microns. This means that the contact region 222 can be far enough from the support element 210 to reduce the contact between the support element 210 and the substrate W during loading and / or unloading. Additionally or alternatively, the height difference between the radially outermost support element 210 and the first sealing member 220 is as shown by y in Figure 4 between approximately 2 microns and 8 microns. The height difference between the radially outermost support element 210 and the first sealing member 220 is the distance between the upper surface 221 of the first sealing member 220 and the distal end face 211 in the y direction, where the y direction is orthogonal to the plane including the radial direction. Having a height difference can also reduce the contact between the support element 210 and the substrate W during loading and / or unloading.

[0099] Setting the contact region 222 at such a distance means that: during loading and / or unloading of the substrate, the substrate W will have a greater interaction with the first sealing member 220 rather than the radially outermost support element 210. In fact, this means that the first sealing member 220 serves as a sacrificial wear area. This can cause a significant reduction in the wear of the outermost support element 210. The distance between the radial outer edge 212 and the contact region 222 can be optimized in the radial direction and / or the y direction to minimize the friction between the outermost support element 210 and the substrate W during loading and / or unloading of the substrate W. The optimal values of the distance D and the distance y can vary depending on the substrate holder 200 and / or the substrate W and / or the application applied to the substrate W.

[0100] The length x of the first sealing member 220 in the radial direction can be greater than 300 microns, or preferably greater than 500 microns. This can be beneficial because the contact region 222 of the first sealing member 220 can be gradually worn by the interaction between the substrate W and the first sealing member 220 during unloading. If the first sealing member 220 is long enough in the radial (i.e., x) direction, the wear of the first sealing member 220 will be less likely to affect the ability of the first sealing member 220 to perform the function of restricting the passage of liquid radially inwards from the first sealing member 220. Thus, providing a first sealing member 220 with a sufficient length (e.g., greater than 300 microns, or preferably greater than 500 microns) may mean that the first sealing member 220 is configured to better control the liquid at the edge of the substrate holder 200 for a longer period of time than known sealing elements, because the first sealing member 220 of the present invention will not be worn in the same way by the interaction with the substrate W.

[0101] Optionally, the substrate holder 200 may include a coating. The coating may be used to cover at least a portion of the substrate holder 200. For example, as described below, the coating may form part of the first sealing member 220 and / or part of at least one of the plurality of support elements 210. The coating may be made of diamond-like carbon (DLC, such as a-CH), diamond, silicon carbide (such as SiSiC or SiC), boron nitride (BN), or boron carbonitride (BCN). The coating may be made substantially or entirely of these materials and / or any derivatives of these materials. Due to the combination of hardness and Young's modulus, these materials may be particularly beneficial. Thus, these materials may have the desired degree of toughness (hardness / Young's modulus).

[0102] The coating may be, for example, a thin layer having the thickness described below. The coating may be used to cover the surfaces of various parts of the substrate holder 200. The coating may be substantially uniform over any part of the substrate holder 200 including the coating. For example, the coating may be provided as a layer having a substantially uniform thickness on the first sealing member 220 and / or at least one of the plurality of support elements 210. For example, the thickness of the coating may vary by less than 50% of the coating thickness of the thickest part of the coating in any part. Preferably, the thickness variation is less than or equal to 30%, or more preferably less than or equal to 20%.

[0103] For example, during loading or unloading of the substrate W, the coating may be beneficial in reducing wear of the substrate holder 200 and / or scratching of the substrate W on any part of the substrate holder 200 in contact with the substrate. The coating may be beneficial in improving the wear resistance of the coated features. This can prevent wear of the features having the coating.

[0104] The coating may be very thin. More specifically, the coating may have a thickness between approximately 0.2 μm and 2 μm. Preferably, the thickness of the coating is between approximately 0.2 μm and 1.5 μm. Preferably, the thickness of the coating is between approximately 0.2 μm and 1 μm. More generally, preferably, the thickness is less than or equal to 2 μm, or preferably less than or equal to 1.5 μm, or preferably less than or equal to 1 μm. The thickness referred to here may be the average thickness on a specific part of the substrate holder 200.

[0105] As Figure 5 shown, at least one of the plurality of support elements 210 may include a coating 214. The coating 214 may have the above-described properties. As Figure 5As shown, the coating 214 may form the distal end face 211 of at least one of the plurality of support elements 210. In other words, the coating 214 may be disposed on the distal end of the protrusion forming at least one of the plurality of support elements 210. The coating 214 may provide a protective layer on the distal end of at least one of the plurality of support elements 210. As Figure 5 shown, the coating 214 may be disposed on a single or multiple ones of the plurality of support elements 210, and optionally, on all of the plurality of support elements 210.

[0106] The coating 214 of at least one of the plurality of support elements 210 may also be referred to as a support member coating. As already described, the coating 214 may reduce the wear of at least one support member 210. Reducing the wear of at least one support member 210 is beneficial because this can increase the service life of the substrate holder 200 such that it can be used to process more substrates.

[0107] In addition, as Figure 5 shown, the first sealing member 220 may include a coating 224. The coating 224 may have the above-described characteristics. As Figure 5 shown, the coating 224 may form the upper surface 221 of the first sealing member 220. In other words, the coating 224 may be disposed on the distal end of the protrusion forming the first sealing member 220. The coating 224 may provide a protective layer on the end of the first sealing member 220. When the coating 224 is disposed on the first sealing member 220, the contact area 222 of the first sealing member 220 may be on the coating 224. The coating 224 on the first sealing member 220 may also be referred to as a sealing member coating.

[0108] The coating 224 may reduce the wear of the first sealing member 220. Reducing the wear of the first sealing member 220 is beneficial because this means that the first sealing member 220 can continue to act as a seal more effectively for a larger number of substrates W being processed as compared to the case where no coating is provided. In addition, if the first sealing member 220 wears, the substrate W may contact at least one support member 210 during loading and unloading, which may reduce the service life of the substrate holder 200. Thus, it is beneficial to prevent the wear of the first sealing member 220 to protect at least one support member 210 for as long as possible / for the processing of as many substrates as possible.

[0109] As Figure 5As shown, the coating 214 may be provided on at least one of the plurality of support elements 210, and the coating 224 may be provided on the first sealing member 220. However, it is not necessary to provide coatings for multiple parts of the substrate holder 200. Thus, for example, the coating may be provided only on one or the other (i.e., the first sealing member 220, or at least one of the plurality of support elements 210).

[0110] Although the above features may reduce wear on the outermost support element 210, this can be improved by changing the shape of the contact area 222. As an addition or alternative to the above features, the contact area 222 of the first sealing member 220 may have a specific geometry. For example, in a cross-section passing radially through the first sealing member 220, the profile of the contact area 222 may have a shape configured such that during unloading of the substrate W, the substrate W contacts the first sealing member 220 via at least two different points of the profile. Figure 6A An example of the contact area 222 configured such that the substrate W contacts the first sealing member 220 via at least two different points during unloading is shown.

[0111] The fact that the profile of the contact area 222 is shaped in such a way means that the substrate W contacts the area in the cross-section of the first sealing member 220 rather than a single point (as shown in Figure 3A and 3B and 4). Additionally or alternatively, the substrate W may interact with the contact area 222 via various different points. For example, the contact points may change during unloading of the substrate W, as will be described in some examples below.

[0112] It is beneficial to have the substrate W contact the first sealing member 220 via at least two different points on the profile because the local stress on the first sealing member 220 can be reduced. This is because during loading and / or unloading, there is an increased contact area between the substrate W and the first sealing member 220, and / or forces from the substrate W are applied to different points on the first sealing member 220. Although different geometries may be provided, the different geometries provide contact between the substrate W and the first sealing member 220 at multiple points, which spreads the forces and reduces the local stress. Thus, this reduces the forces acting on the underside of the substrate W. Subsequently, this reduces the formation of scratches on the lower surface of the substrate W (scratches may generate particles that contaminate the system). Thus, providing such a contact area 222 can be beneficial for reducing contamination.

[0113] Various different geometries of the profile may be provided. For example, from the upper surface 221 of the first sealing member 220 to the radially outer edge 223 of the first sealing member 220, the profile may be linear. This is in Figure 6Ais shown, where the contact area 222 is formed by an inclined portion having an angle θ. In other words, the first sealing member 220 may have a chamfered edge or a beveled edge forming the contact area 222. The linear profile from the upper surface 221 of the first sealing member 220 to the radially outer edge 223 of the first sealing member 220 may be at a negative gradient between approximately 0.15 micrometers per millimeter and 3 micrometers per millimeter with respect to the upper surface 221 of the first sealing member 220.

[0114] As with Figure 4 the first sealing member 220 described, the distance between the contact area 222 and the support element 210 may be defined by Figure 6A the distance D in the radial direction shown. This distance may additionally or alternatively be defined by the distance y1 between the distal end face 211 of the support element 210 and the upper surface 221 of the first sealing member 220. This may be the same as Figure 4 the distance y referred to in

[0115] and described above. Both of these distances affect how the substrate W interacts with each of these components during unloading.

[0116] As described above, a coating 224 may be provided on the upper surface of the first sealing member 220. As Figure 6B shown, the coating 224 may be provided only on the contact area 222, where the coating may have the greatest effect. Thus, the coating 224 may be formed as part of the first sealing member 220 and may form the contact area 222 as described above and below.

[0117] In one embodiment, the profile may include a plurality of linear portions from the upper surface 221 of the first sealing member 220 to the radially outer edge 223 of the first sealing member 220. This is in Figure 7A , 7Bshown in FIGS. 7C. In one embodiment, the shape of the profile may be curved from the upper surface 221 of the first sealing member 220 to the radially outer edge 223 of the first sealing member 220. This is shown in Figure 7D , 7E and FIGS. 7F. Additionally or alternatively, the outer edge of the first sealing member 220 may be circular. This may be a circular chamfer on the outer edge forming the contact area 222. The shape of the profile may be part of an ellipse or a circle. For example, the shape of the profile may be Figure 7D a part of the elliptical circle shown. The shape of the profile may be substantially stepped as shown in Figure 7F and 7G . Any shape that provides multiple contact points will reduce the local stress on the substrate W compared to a single point contact in cross-section. The substrate W may contact the contact area 222 via a line contact, for example, when the edge is curved, there are more than a single contact point between the substrate W and the first sealing member 220 such that a contact line can be seen in cross-section. Shapes with multiple discrete contact points (instead of line contact) will generally have a smaller total contact area and will wear out faster. Figures 7A - 7G The shapes shown in are examples of shapes that may be particularly advantageous in the case of a particular substrate and / or system and / or substrate unloading setup / sequence. Some of these shapes may have improved manufacturability and / or an improved effect on the performance of the substrate W used, such as reducing warping of the substrate W.

[0118] It is beneficial to make the surface of the contact area 222 as smooth as possible. This reduces the local stress on the lower surface of the substrate W. Thus, the contact area 222 may be configured to reduce the frictional force between the substrate W and the first sealing member 220 when they interact. For example, the contact area 222 may be polished.

[0119] Figure 6A and 7A -7G show that the various different profiles mean that the contact area 222 can provide a contact area between the substrate W and the first sealing member 220. This is beneficial because it distributes the forces applied to the first sealing member 220 and the substrate W and means reducing the local stress to reduce or prevent scratching on the lower surface of the substrate W, i.e., reducing or preventing damage to the lower surface of the substrate W. The contact area may be provided by multiple discrete contact points or a line contact in cross-section.

[0120] Although not described in the various different profiles shown in Figures 7A - 7G , any sealing member having these profiles may have the coating 224 as described above.

[0121] The first sealing member 220 is configured to surround the plurality of support elements 210 and is positioned radially outward of the plurality of support elements 210, meaning that all the support elements 210 are radially inward of the first sealing member 220 in a plane. Thus, the first sealing member 220 can form the outermost contact point with the lower surface of the substrate W during loading and / or unloading. This allows for reduced wear on the support elements 210 as described above. The first sealing member 220 can surround the support elements 210 as discrete members in a plane surrounding all the support elements 210. For example, the first sealing member 220 can be circular in a plane. The first sealing member 220 may not have a uniform cross-section and thus, as Figure 4 -6, Figures 7A - 7G , Figure 8 or Figure 9 shown, the shape of the first sealing member 220 may be different. The first sealing member 220 can optionally have a gap such that the first sealing member 220 can be provided by a plurality of discrete members surrounding all the support elements 210.

[0122] Due to the liquid in the vicinity of this part of the system, the space between the lower surface of the substrate W and the body 201 of the substrate holder 200 may have a humid atmosphere. The disadvantage of a humid atmosphere is that the support elements 210 may oxidize. Oxidation of the support elements 210 is harmful because it reduces the achievable flatness of the substrate W supported by the support elements 210. The substrate holder 200 can include at least one extraction opening 230 formed in the body 201 for extracting fluid from between the body surface 202 and the substrate W into the body 201. The at least one extraction opening 230 can be part of a sealing mechanism. The extraction opening 230 as described below can be provided to help avoid having a humid atmosphere between the body surface 202 and the substrate W.

[0123] The at least one extraction opening 230 can be arranged radially inward of the first sealing member 220 and adjacent to the first sealing member 220. Thus, there may not be any other features such as support elements 210 between the at least one extraction opening 230 and the first sealing member 220. The extraction opening 230 can be connected to a low-pressure source. Thus, any liquid reaching the extraction opening 230 can be extracted through the body 201. This means restricting further entry of liquid into the space between the body surface 202 and the substrate W. For example, when there is no liquid to be extracted, the extraction opening 230 can also extract gas. A mixture of liquid and gas can be extracted through the extraction opening 230. The at least one extraction opening 230 can be used to help provide the above-described pressure drop and / or low-pressure region.

[0124] At least one extraction opening 230 may be formed by a plurality of openings. The extraction openings 230 may be spaced apart from each other all around the first sealing member 220. The extraction openings 230 may be discrete openings in the body surface 202. Alternatively, the extraction openings 230 may be grooves formed in the body surface 202. Alternatively, grooves may be formed in the body surface 202 of the extraction openings 230 and may be exposed from the body 202 at the bottom of the grooves. The grooves may be segmented, with one or more openings in each segment. These segments may be regarded as a plurality of recesses.

[0125] By connecting at least one extraction opening 230 to a negative pressure, the liquid that actually flows towards the edge of the substrate W can be removed through the extraction opening 230. Once the edge of the substrate W is no longer covered by the liquid, the lower surface of the substrate W is dried when the liquid is removed.

[0126] As described above, the substrate holder 200 may additionally include a second sealing member 240. Although Figure 4 , Figure 5 , Figure 6A , Figure 6B , Figure 8 and Figure 9 depict the second sealing member 240, this sealing member is optional and may not be provided together with the first sealing member 220. The second sealing member 240 may be positioned radially inward of at least one extraction opening 230 (if provided). The second sealing member 240 may be positioned radially outward of the support element 210. The second sealing member 240 may be configured to surround or enclose at least one support element 210. Thus, all the support elements 210 may be located radially inward of the second sealing member 240. Alternatively, at least one of the support elements 210 may be located radially outward of the second sealing member 240. In other words, the second sealing member 240 may be located radially inward of one or more support elements 210. For example, at least the radially outermost support element 210 may be positioned between the first sealing member 220 and the second sealing member 240. At least the radially outermost support element 210 may be arranged alternately with at least one extraction opening 230 in a line surrounding the second sealing member 240.

[0127] As a supplement or alternative to the embodiments described above, the substrate holder 200 may include at least one additional member 250. The additional member 250 may have a contact area 252 configured to contact the substrate W during loading or unloading of the substrate W. The contact area 252 of the additional member 250 may be similar to the contact area 222 of the first sealing member 220 and may have similar characteristics as described above for the contact area 222 of the first sealing member 220. In addition to the above-described sealing unit / first sealing member 220, the additional member 250 may be provided. In this embodiment, both the first sealing member 220 and the additional member 250 may be configured to contact the substrate W during loading and unloading of the substrate W. The additional member 250 may have a third height that is less than the first height. In other words, the support element 210 may be higher than the additional member 250.

[0128] The at least one additional member 250 may hereinafter be referred to as the additional member 250, but it should be understood that reference to an additional member may also include a plurality of additional members. Thus, the additional member 250 may be formed of a plurality of individual parts or protrusions.

[0129] The additional member 250 may provide a support function similar to that of the first sealing member 220 described above. Thus, the additional member 250 may be configured to contact the substrate W during loading and / or unloading of the substrate W. By adding the additional member 250 radially outward of at least one support member 210, damage to the at least one support member 210 may be reduced or prevented. The additional member 250 may act as a sacrificial bump / area.

[0130] More specifically, the substrate holder 200 may include an additional member 250 protruding from the body surface 202 and having an upper surface 251. The at least one additional member 250 may be positioned radially outward of the first sealing member 220 and surround the first sealing member. The upper surface 251 of the additional member 250 may have a contact area 252 configured to contact the substrate W during loading and / or unloading of the substrate W. The position of the contact area 252 of the additional member 250 is arranged at a sufficient distance from the plurality of support elements 210 such that during loading and / or unloading of the substrate W, the force applied by the substrate W to the additional member 250 is greater than the force applied by the substrate W to the plurality of support elements 210.

[0131] In addition, the additional member 250 may include the coating 254 as described above. Thus, the coating may be formed of diamond-like carbon (DLC, such as a-CH), diamond, silicon carbide (such as SiSiC or SiC), boron nitride (BN), or boron carbonitride (BCN). The coating 254 may form the upper surface 251 of the additional member 250, and the contact area 252 of the additional member 250 may be located on the coating 254. The coating 254 may have other characteristics such as thickness as described above with respect to the seal member coating 224 and / or the support member coating 214. The coating 254 of the additional member 250 may be alternatively referred to as the additional member coating.

[0132] The coating 254 is as Figure 8 shown. However, in the absence of the coating 254, the additional member 250 may be provided in combination with the first seal member 220 as described above. The coating 254 of the additional member 250 may be provided only on the contact area 252 of the additional member 250.

[0133] In another embodiment, the substrate holder 200 may include an alternative seal member 260 and the additional member 250. The alternative seal member 260 may replace the above-described first seal member 220. In this embodiment, only the additional member 250 may have a contact area 252 configured to contact the substrate W during loading and / or unloading of the substrate W. In other words, in this embodiment, the alternative seal member 260 is not configured to contact the substrate W during loading and / or unloading of the substrate W as in the embodiments described above. For example, the alternative seal member 260 may be positioned such that it does not contact the substrate W during loading or unloading. For example, the alternative seal member 260 may be located radially too far inward to contact the substrate W during loading and / or unloading. Thus, the alternative seal member 260 may provide a seal, for example, by reducing or affecting the gas / fluid flow as described above with respect to the first seal member 220, but does not contact the substrate W during loading or unloading, as done by the first seal member 220.

[0134] More specifically, the substrate holder 200 includes a body 201, a plurality of support elements 210, a sealing unit, and at least one additional member 250. The body 201 has a body surface 202. The plurality of support elements 210 protrude from the body surface 202. Each support element 210 may have a distal end face 211 configured to support the substrate W and a first height. The sealing unit may be configured to restrict the flow or passage of liquid and / or gas radially inward between the substrate W and the body surface 202 through the sealing unit. The sealing unit may include a first sealing member 220 protruding from the body surface 202. The first sealing member 220 may have a second height less than the first height. The first sealing member 220 may be positioned radially outward of and surrounding the plurality of support elements 210. At least one additional member 250 protrudes from the body surface 202 and has an upper surface 251. At least one additional member 250 may be positioned radially outward of and surrounding the plurality of support elements 210. Additionally, at least one additional member 250 may be positioned radially outward of and surrounding the sealing unit. At least one additional member 250 may include a coating 254 that forms the upper surface 251 of the additional member 250. The coating 254 may have a contact area 252 configured to contact the substrate W during loading and / or unloading of the substrate W. The coating 254 may be made of diamond-like carbon (DLC, such as a-CH), diamond, silicon carbide (such as SiSiC or SiC), boron nitride (BN), or boron carbonitride (BCN). The position of the contact area 252 of the additional member 250 may be arranged at a sufficient distance from the plurality of support elements 210 such that during loading and / or unloading of the substrate W, the force applied by the substrate W to the additional member 250 is greater than the force applied by the substrate W to the plurality of support elements 210.

[0135] In the present embodiment, the sealing unit may include an alternative sealing member 260 as described above. The alternative sealing member 260 may protrude from the body surface 202. The alternative sealing member 260 may be radially outward of the plurality of support elements 210. The alternative sealing member 260 may surround the plurality of support elements 210. The alternative sealing member 260 may operate in the same manner as the first sealing member 220 described above. However, in this embodiment, the alternative sealing member 260 may be configured such that it generally does not contact the substrate W during loading and / or unloading. The sealing unit may include a second sealing member 240 as described above. Thus, the second sealing member 240 may protrude from the body surface and may be positioned radially outward of the alternative sealing member 260.

[0136] In any of the embodiments described above, including the additional member 250 may have characteristics similar to the first sealing member 220 described above. For example, according to Figure 6A 、6B and 7A - 7G. Additionally, the additional member 250 may have a contact region, and the contact region may have a profile as described above with respect to the first sealing member 220 according to Figure 6A 、 Figure 6B and Figures 7A through 7G . More specifically, in a cross - section of the additional member 250 through other components in the radial direction, the profile of the contact region 252 of the additional member 250 may have a shape configured such that during loading and / or unloading of the substrate W, the substrate W contacts the additional member 250 via at least two different points of the profile. The additional member 250 may include a coating 254 only on the contact region 252 having the profile, as described for the first sealing member 220 as shown in Figure 6B .

[0137] The additional member 250 may be provided in the shape of a continuous loop. In other words, the additional member 250 may be circular in a plane, or more specifically, loop - shaped or annular. Thus, the additional member 250 may have an annular shape. The additional member 250 may include a plurality of segments and may optionally be a segmented loop. In a segmented loop, there may be a plurality of additional member portions, and there may be a gap between each adjacent additional member portion. The additional member portions may be referred to as radial spokes. The gap between adjacent additional member portions may be the same length as either or both of the adjacent portions, or less than the length of either or both of the adjacent portions. In other words, the distance between each additional member portion may be equal to or less than the width of one or both of the adjacent additional member portions. At least one of the gaps between adjacent additional member portions (i.e., the spacing between adjacent portions) may be on the order of tens or hundreds of micrometers. At least one of the gaps between adjacent additional member portions may be as narrow as approximately 10 micrometers. At least one of the gaps may be between 0.5 and 5 mm. Some or all of the gaps may have these dimensions. Setting small gaps may be advantageous because any contaminants, for example from the interaction between the additional member 250 and the underside of the substrate W, can be trapped in the gaps while still providing a relatively large contact area.

[0138] The additional member 250 may be provided by a row of multiple individual nodules or protrusions spaced apart from each other to form an annular shape in a plane. In other words, the additional member 250 may include a plurality of additional support elements. For example, an individual nodule or protrusion may have a diameter of approximately 100 to 1000 micrometers. The distance from the middle of one nodule or protrusion to the middle of an adjacent nodule or protrusion may be approximately 1 to 3 mm. The upper surface 251 of the additional member 250 may be slightly rounded or polished, as described for the first sealing member 220 above, to reduce wear of the additional member 250.

[0139] Additionally, the additional member 250 may have a height (a third height) that is smaller than the height of at least one support member 210. This means that the additional member 250 can bear the load during the loading and unloading of the substrate W. However, during use, such as during the exposure of the substrate W, the additional member 250 may not be in contact with the substrate W. For the first sealing member 220, the distance between the additional member 250 and at least one support member 210 can be optimized as Figure 4 described.

[0140] The position of the contact area 252 of the additional member 250 relative to the support element 210 can be controlled in various different ways. For example, as Figure 9 shown, the main dimension relates to the distance between the radially outer edge 212 of the distal end face 211 of the radially outermost support element 210 and the outer upper edge of the upper surface 251 of the additional member 250. This dimension relates to these specific parts of the additional member 250 and the support element 210 because these parts are the parts of these components that will contact the lower surface of the substrate W during the loading and / or unloading of the substrate W.

[0141] This distance can be defined by the radial distance D. This distance can additionally or alternatively be defined by the distance y between the distal end face 211 of the support element 210 and the upper surface 251 of the additional member 250. Both of these distances will affect how the substrate W interacts with each of these components during loading and / or unloading.

[0142] In this example, the contact area 252 is shown as an edge contact point in cross-section. Thus, in this embodiment, the contact area 252 is formed by the same contact points around the circumference of the additional member 250. This contact area 252 can be similar to the contact area for the Figure 4 first sealing member 220 shown. The position of the contact area 252 relative to the support element 210 is configured to reduce the wear of the support element 210 during the unloading of the substrate W.

[0143] In one embodiment, the radial distance D from the radially outer edge 212 of the distal end face 211 to the contact area 252 is greater than 1000 microns, and preferably greater than 1500 microns. The radial distance D is preferably between about 1000 and 3000 microns, i.e., 1 to 3 mm. This means that the contact area 252 can be sufficiently far from the support element 210 to reduce the contact between the support element 210 and the substrate W during loading and / or unloading. Additionally or alternatively, the height difference between the radially outermost support element 210 and the additional member 250 is between approximately 0.5 microns and 5 microns, as Figure 9is shown by y. Preferably, the height difference is greater than or equal to 3 microns to reduce the likelihood of the additional member 250 contacting the lower side of the substrate W during exposure of the substrate W. The height difference between the radially outermost support element 210 and the additional member 250 is the distance between the upper surface of the additional member 20 in the y direction and the distal end face 211, where the y direction is orthogonal to the plane including the radial direction. Having a height difference can also reduce the contact between the support element 210 and the substrate W during loading and / or unloading.

[0144] Setting the contact area 252 at such a distance means that during loading and / or unloading of the substrate W, the substrate W will interact more with the additional member 250 rather than the radially outermost support element 210. In fact, this means that the additional member 250 is used as a sacrificial wear area. This can result in a significant reduction in the wear of the outermost support element 210. The distance between the radially outer edge 212 and the contact area 252 in the radial and / or y direction can be optimized to minimize the friction between the outermost support element 210 and the substrate W during loading and / or unloading of the substrate W. The optimal values of the distance D and the distance y can vary depending on the substrate holder 200 and / or the substrate W and / or the application applied to the substrate W.

[0145] As indicated above, the substrate holder 200 can include at least one support element 210 between the first sealing member 220 and the second sealing member 240. This is shown in Figure 10 Thus, the outermost support element 210 can be arranged adjacent to the first sealing member 220 and the second sealing member 240. Therefore, the second sealing member 240 can only surround a part rather than all of the support element 210.

[0146] In this example, as in Figure 4 the first sealing member 220 depicted in, the distance between the contact area 222 and the support element 210 can be defined by the Figure 10 radial distance D shown in. This can be the same value / range as the distance D referred to in Figure 4 and described above. This distance can additionally or alternatively be defined by the distance y between the distal end face 211 of the support element 210 and the upper surface 221 of the first sealing member 220. This can be the same value / range as the distance y referred to in Figure 4 and described above. The distance x is the full length of the first sealing member 220. This can be the same value / range as the distance x referred to in Figure 4 and described above. All of these distances will affect how the substrate W interacts with each of these components during unloading.

[0147] A plurality of support elements 210 may be provided between the first sealing member 220 and the second sealing member 240. Optionally, at least one extraction opening 230 may also be provided. For example, the support elements 210 and the extraction openings 230 may alternate in the space between the first sealing member 220 and the second sealing member 240. In other words, Figure 10 A cross-section of a portion of the substrate holder 200 through the outermost support element 210 between the first sealing member 220 and the second sealing member 240 is shown. However, at different radial positions, similar cross-sections may show the extraction openings 230 between the first sealing member 220 and the second sealing member 240, as Figure 4 shown.

[0148] At least one outermost support element 210 may also be provided in a similar position in other embodiments. For example, when other components 250 are arranged as in Figure 8 or are arranged between an alternative sealing member 260 and the second sealing member 240 in Figure 9 , the outermost support element 210 may be provided between the first sealing member 220 and the second sealing member 240. These members may include contact areas 222, 252 and / or coatings 254, as described in any of the embodiments or variations described above.

[0149] As described above, the substrate holder 200 may be configured to control the pressure between the body 201 and the substrate W when the substrate W is unloaded. This can be done in various ways and any known method / system can be used. The present invention may include a lithographic apparatus as described in any of the examples of the variations described above. The lithographic apparatus may include a substrate holder 200 configured to support the substrate according to any one of the embodiments or variations.

[0150] Although a lithographic apparatus may be specifically mentioned herein for use in IC manufacturing, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guiding and probing patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0151] Although embodiments of the present invention may be specifically mentioned herein in the context of a lithographic apparatus, embodiments of the present invention may be used in other devices. Embodiments of the present invention may form part of a mask inspection device, a metrology device, or any device for measuring or processing an object such as a wafer (or other substrate) or a mask (or other patterning device). These devices are commonly referred to as lithographic tools. Such lithographic tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0152] Although embodiments of the present invention may have been specifically mentioned above in the context of optical lithography, it should be understood that the present invention is not limited to optical lithography and may be used in other applications, such as imprint lithography, where the context permits.

[0153] The drawings are intended to illustrate the various features described above. The drawings are not drawn to scale. The relative widths and heights of different features may vary with respect to other features. For example, the additional member 250 is shown as being narrower than the first sealing member 220 and the second sealing member 240. However, the additional member 250 may be the same width (i.e., the same length in the x direction), or may be wider (i.e., have a greater length in the x direction).

[0154] Although specific embodiments of the invention have been described above, it should be understood that the invention may be practiced in other ways different from those described. The above description is intended to be illustrative, not restrictive. Thus, those skilled in the art will appreciate that the described invention may be modified without departing from the scope of the claims set forth below.

Claims

1. A substrate holder configured to support a substrate in a lithographic apparatus, the substrate holder comprising: A body having a body surface; A plurality of first support elements protruding from the body surface, each of the first support elements having a distal end face configured to support a substrate and a first height; A sealing unit including a first sealing member protruding from the body surface, the first sealing member having an upper surface and a second height less than the first height and positioned radially outward of the plurality of first support elements and surrounding the plurality of first support elements; And A plurality of second support elements protruding from the body surface and positioned radially outward of the first sealing member, wherein the second support elements have a distal surface configured to support a substrate and a first height; Wherein, the plurality of first support elements, the first sealing member or the plurality of second support elements include a coating made of diamond-like carbon, diamond, silicon carbide, boron nitrite or boron carbonitride, and the coating forms the distal surface of the plurality of support elements and / or forms the upper surface of the first sealing member.

2. A substrate holder for use in a lithographic apparatus and configured to support a substrate, the substrate holder comprising: A body having a body surface; A plurality of first support elements protruding from the body surface, each of the first support elements having a distal end face configured to support a substrate and a first height; A first sealing member protruding from the body surface, the first sealing member having an upper surface and having a second height less than the first height and positioned radially outward of the plurality of first support elements and surrounding the plurality of first support elements, One or more second support elements protruding from the body surface and positioned outside the sealing member, each of the second support elements having a distal end face configured to support a substrate and a first height, and wherein the one or more second support elements are configured to support the substrate; And A second sealing member protruding from the body surface and positioned outside the one or more second support elements and the first sealing member and surrounding the one or more second support elements and the first sealing member; Wherein, the plurality of first support elements, the first sealing member and / or the second sealing member and / or the one or more second support elements include a coating made of diamond-like carbon, diamond, silicon carbide, boron nitrite or boron carbonitride, and the coating forms the distal surface of the plurality of first support elements, forms the distal end face of the one or more second support elements and / or forms the upper surface of the first sealing member and / or the second sealing member.

3. A substrate holder configured to support a substrate in an immersion lithographic apparatus, the substrate holder comprising: A body having a body surface; A plurality of support elements protruding from the body surface, each of the support elements having a distal end face configured to support a substrate and a first height; A sealing unit including a first sealing member protruding from the body surface, the first sealing member having an upper surface and a second height less than the first height and positioned radially outward of the plurality of support elements and surrounding the plurality of support elements, and the upper surface having a contact area configured to contact the substrate during substrate loading and / or unloading, and Wherein, the position of the contact area is arranged at a distance from the plurality of support elements sufficient to cause the force applied to the first sealing member by the substrate to be greater than the force applied to the plurality of support elements by the substrate during substrate loading and / or unloading. Wherein the sealing unit is configured to restrict the passage of liquid radially inwards between the substrate and the body surface through the sealing unit.

4. A substrate holder configured to support a substrate in an immersion lithographic apparatus, the substrate holder comprising: A body having a body surface; A plurality of support elements protruding from the body surface, wherein each support element has a distal end face configured to support a substrate and a first height; A sealing unit including a first sealing member protruding from the body surface, the first sealing member having an upper surface and a second height less than the first height and positioned radially outward of the plurality of support elements and surrounding the plurality of support elements, and the upper surface having a contact area configured to contact the substrate during substrate loading and / or unloading. Wherein, the difference between the first height of the radially outermost support element and the second height of the first sealing member is between about 2 micrometers and 8 micrometers; and Wherein the sealing unit is configured to restrict the passage of liquid radially inwards between the substrate and the body surface through the sealing unit.

5. A substrate holder configured to support a substrate in an immersion lithographic apparatus, the substrate holder comprising: A body having a body surface; A plurality of support elements protruding from the body surface, wherein each support element has a distal end face configured to support a substrate and a first height; A sealing unit including a first sealing member protruding from the body surface, the first sealing member having a second height less than the first height and positioned radially outward of the plurality of support elements and surrounding the plurality of support elements, and At least one additional member protruding from the body surface and having an upper surface and a third height less than the first height, the at least one additional member being positioned radially outward of the sealing unit and surrounding the sealing unit, Wherein, the difference between the first height of the radially outermost support element and the third height of the additional member is between about 0.5 micrometers and 5 micrometers; and Wherein the sealing unit is configured to restrict the passage of liquid radially inwards between the substrate and the body surface through the sealing unit.

6. A substrate holder configured to support a substrate in an immersion lithography apparatus, the substrate holder comprising: A body having a body surface; A plurality of support elements protruding from the body surface, wherein each support element has a distal end face configured to support a substrate and a first height; A sealing unit including a first sealing member protruding from the body surface, the first sealing member having an upper surface and a second height less than the first height and positioned radially outward of the plurality of support elements and surrounding the plurality of support elements, the upper surface having a contact area configured to contact the substrate during substrate loading and / or unloading; And Wherein, the position of the contact area is arranged at a distance from the plurality of support elements sufficient to cause the force applied to the first sealing member by the substrate to be greater than the force applied to the plurality of support elements by the substrate during substrate loading and / or unloading, and the contact area is positioned adjacent to the radially outer edge of the first sealing member, the radial distance from the radially outer edge of the distal end face to the contact area being greater than 1000 microns, or the height difference between the radially outermost support element and the first sealing member being between 2 microns and 8 microns.

7. A substrate holder configured to support a substrate in an immersion lithography apparatus, the substrate holder comprising: A body having a body surface; A plurality of support elements protruding from the body surface, each support element having a distal end face configured to support a substrate and a first height; A first sealing member protruding from the body surface, the first sealing member having a second height less than the first height and positioned radially outward of the plurality of support elements and surrounding the plurality of support elements, At least one extraction opening formed in the body for extracting fluid from between the body surface and the substrate to the body when the substrate is supported by the plurality of support elements, the at least one extraction opening being arranged outside the plurality of support elements and the first sealing member; And A second sealing member protruding from the body surface, the second sealing member having a third height less than the first height and positioned radially outward of the first sealing unit and the at least one extraction opening and surrounding the first sealing unit and the at least one extraction opening, and An additional member protruding from the body surface and having an upper surface, the additional member being positioned outside the first sealing member and surrounding the first sealing member.

8. A lithography apparatus comprising a substrate holder according to any one of claims 1 - 7.

Images