System for changing the shape of a substrate

Abstract

Disclosed herein is a substrate support mechanism configured to support a substrate. The substrate support mechanism includes a substrate support having a substantially planar support surface for the substrate, and a substrate shaping system including one or more substrate shaping devices. Each substrate shaping device is movable relative to the substrate support. Each substrate shaping device is positioned to apply an electrostatic force to an outer periphery of the substrate when the substrate is provided on the support surface.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS)

[0001] This application claims priority to European Patent Application No. 23156107.7, filed February 10, 2023, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a technique for changing the shape of a substrate. The shape deformation of a substrate can be at least partially reduced by applying an electrostatic force to the outer periphery of the substrate. [Background technology]

[0003] A lithographic apparatus is a machine configured to apply a desired pattern onto a substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus can, for example, project a pattern in a patterning device (e.g. a mask or reticle) onto a layer of radiation-sensitive material (resist) provided on the substrate.

[0004]

[0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements are constantly shrinking, while the amount of functional elements, such as transistors, per device has been steadily increasing for decades, following a trend commonly referred to as "Moore's Law." To keep up with Moore's Law, the semiconductor industry pursues technologies capable of producing increasingly smaller features.

[0005] To project a pattern onto a substrate, a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Lithographic apparatus using extreme ultraviolet (EUV) radiation having a wavelength in the range of 4 to 20 nm, for example 6.7 nm or 13.5 nm, can be used to form smaller features on a substrate than lithographic apparatus using radiation with a wavelength of, for example, 193 nm.

[0006]

[0006] In a conventional lithographic apparatus, a substrate to be exposed may be supported by a substrate support (i.e., an object that directly supports the substrate), which in turn is supported by a substrate table (a mirror block or stage, i.e., an object such as a table that supports the substrate support and provides an upper surface surrounding the substrate support). Often, the substrate support is a flat, rigid disk that has a size and shape corresponding to the substrate (but may have a different size or shape). It has an array of protrusions, called burls or pimples, protruding from at least one side. The substrate support may also have arrays of protrusions on two opposite sides. In this case, when the substrate support is placed on the substrate table, the body of the substrate support is held a small distance above the substrate table, with the ends of the burls on one side of the substrate support resting on the surface of the substrate table. Similarly, when the substrate rests on the burls on the opposite side of the substrate support, the substrate is spaced apart from the body of the substrate support. The purpose of this is to help prevent particles (i.e., contaminant particles such as dust particles) that may be present on either the substrate table or the substrate support from distorting the substrate support or the substrate. Since the total surface area of ​​the burls is a small fraction of the total area of ​​the substrate or substrate support, any particles will likely reside between the burls and their presence will have no effect. Often the substrate support and substrate are housed in a recess in the substrate table so that the top surface of the substrate is substantially flush with the top surface of the substrate table.

[0007]

[0007] When using a high-throughput lithography apparatus, the substrate is subjected to high accelerations, so simply resting the substrate on burls of the substrate support is not sufficient; the substrate must be clamped in place. Two methods for clamping a substrate in place are known: vacuum clamping and electrostatic clamping. In vacuum clamping, the space between the substrate support and the substrate, and optionally the space between the substrate table and the substrate support, is partially evacuated, so that the substrate is held in place by high pressure of a gas or liquid above the substrate. However, vacuum clamping may not be used when the beam path and / or environment near the substrate or substrate support is held at low or very low pressure, for example for extreme ultraviolet (EUV) radiation lithography. In this case, it may not be possible to create a sufficiently large pressure difference on both sides of the substrate (or substrate support) for clamping. Therefore, electrostatic clamping may be used. In electrostatic clamping, a potential difference is created between an electrode plated on the substrate or its underside and an electrode provided on or within the substrate table and / or substrate support. These two electrodes act as a large capacitor and can generate a large clamping force with a moderate potential difference. In an electrostatic mechanism, a pair of electrodes, one on the substrate table and one on the substrate, can clamp the substrate table, substrate support and the complete stack of substrates together. In known mechanisms, one or more electrodes are provided on or in the substrate support so that the substrate support is clamped to the substrate table and the substrate is separately clamped to the substrate support.

[0008] There is a need for an improved substrate support that includes one or more electrostatic clamps for clamping the substrate support to a substrate table and / or for clamping a substrate to the substrate support, and more generally, for an improved object holder that includes one or more electrostatic clamps for holding an object holder, such as a patterning device holder, to a table and / or for holding an object relative to an object holder. Summary of the Invention

[0009] According to a first aspect of the present invention, there is provided a substrate support arrangement configured to support a substrate, the substrate support arrangement comprising a substrate support providing a substantially planar support surface for the substrate, and a substrate shaping system including one or more substrate shaping devices, each movable relative to the substrate support and arranged to apply an electrostatic force to a periphery of the substrate when the substrate is provided on the support surface.

[0010] According to a second aspect of the present invention, there is provided a lithographic apparatus comprising a substrate support arrangement according to the first aspect.

[0011] According to a third aspect of the present invention, there is provided a method of altering a shape of a substrate, the method comprising loading a substrate onto a substrate support of a substrate support mechanism according to the first aspect, and applying an electrostatic force to a periphery of the substrate. [Brief explanation of the drawings]

[0012]

[0012] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0013] [Figure 1] 1 illustrates a schematic representation of an EUV lithography system including a lithographic apparatus and a radiation source. [Figure 2]

[0014] 1 is a cross-sectional view of an object holder according to one embodiment of the present invention; [Figure 3]

[0015] 1 shows a schematic representation of a DUV lithography apparatus; [Figure 4]

[0016] 1 shows a schematic cross section of a substrate support. [Figure 5]

[0017] 1 illustrates schematically a substrate support mechanism used in an EUV system according to a first embodiment. [Figure 6]

[0018] 5 illustrates schematically a substrate support mechanism for use in a DUV system according to a second embodiment; [Figure 7]

[0019] 10 shows a schematic representation of a portion of a seal according to a second embodiment;

[0014]

[0020] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and their detailed description are not intended to limit the invention to the particular forms disclosed, but rather are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION

[0015]

[0021] 1 shows a lithography system comprising a radiation source SO and a lithography apparatus LA. The source SO is configured to generate a beam of EUV radiation B and to provide this beam of EUV radiation B to the lithography apparatus LA. The lithography apparatus LA includes an illumination system IL, a support structure MT configured to support a patterning device MA (e.g. a mask or reticle), a projection system PS, and a substrate table WT configured to support a substrate W.

[0016]

[0022] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. To that end, the illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11. Together, the facetted field mirror device 10 and the facetted pupil mirror device 11 provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The illumination system IL may include other mirrors or devices in addition to or instead of the facetted field mirror device 10 and the facetted pupil mirror device 11.

[0017]

[0023] After being conditioned in this way, the EUV radiation beam B interacts with the patterning device MA. This interaction results in a patterned EUV radiation beam B'. The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. To this end, the projection system PS may comprise a plurality of mirrors 13, 14, which are configured to project the patterned EUV radiation beam B' onto the substrate W, which is held by a substrate table WT. The projection system PS may apply a demagnification factor to the patterned EUV radiation beam B' to form images of features that are smaller than corresponding features on the patterning device MA. For example, a demagnification factor of 4 or 8 may be applied. Although in Figure 1 the projection system PS is illustrated as having only two mirrors 13, 14, the projection system PS may include a different number of mirrors, for example 6 or 8 mirrors.

[0018]

[0024] The substrate W may include a previously formed pattern, and if this is the case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the previously formed pattern on the substrate W.

[0019]

[0025] A relative vacuum, ie a small amount of gas (eg hydrogen) at a pressure well below atmospheric pressure, may be provided in the source SO, the illumination system IL and / or the projection system PS.

[0020]

[0026] The source SO may be a laser-produced plasma (LPP) source, a discharge-produced plasma (DPP) source, a free-electron laser (FEL), or any other source capable of producing EUV radiation.

[0021]

[0027] 2 is a cross-sectional view of the substrate support 20. The substrate support 20 is configured to support a substrate W.

[0022]

[0028] The substrate table WT includes a substrate support 20 and a substrate stage (not shown). The substrate stage includes a recess in which the substrate support 20 is held. The substrate support 20 is configured to hold the substrate W relative to the substrate stage of the substrate table WT.

[0023]

[0029] As shown in FIG. 2, the substrate support 20 includes a support body 21. The support body 21 is a plate-like disk. As shown in FIG. 2, the support body 21 includes a plurality of burls 22. The burls 22 are protrusions that protrude from the surface of the support body 21. As shown in FIG. 2, the burls 22 have distal ends 23. The support body 21 is configured such that the distal ends 23 define a support surface 24 for supporting the substrate W. The underside of the substrate W contacts the distal ends 23 of the burls 22. The position of the underside of the substrate W corresponds to the support surface 24. The burls 22 are arranged so that the substrate W is placed approximately flat on the substrate support 20.

[0024]

[0030] 2, the burls 22 are not shown to scale. In a practical embodiment, hundreds, thousands, or tens of thousands of burls 22, e.g., 200 mm, 300 mm, or 450 mm in diameter, may be dispersed throughout the substrate support 20. The tips or distal ends 23 of the burls 22 may be, e.g., 1 mm. 2Because the burls 22 have small areas less than 10% of the total surface area of ​​the substrate support 20, the total area of ​​all the burls 22 on one side of the substrate support 20 is less than about 10% of the total surface area of ​​the substrate support 20. This configuration of the burls 22 ensures that particles that may be present on the surface of the substrate W, substrate support 20, or substrate table WT fall between the burls 22 and are therefore likely not to cause deformation of the substrate W or substrate support 20. The burl arrangement, which may form a pattern, may be regular or varied as desired to provide appropriate force distribution on the substrate W and substrate table WT. The burls 22 may have any shape in plan, but are typically circular in plan. The burls 22 may have the same shape and dimensions throughout their entire height, but are typically tapered. The burls 22 may protrude above the remainder of the object-facing surface of the substrate support 20 (i.e., the upper surface of the electrostatic sheet 25) by a distance of about 1 μm to about 5 mm, preferably about 5 μm to about 250 μm, and preferably about 10 μm. Therefore, the vertical distance between distal end 23 of burl 22 and the upper surface of electrostatic sheet 25 is about 1 μm to about 5 mm, desirably about 5 μm to about 250 μm, and desirably about 10 μm. The thickness of support body 21 of substrate support 20 can be within a range of about 1 mm to about 50 mm, desirably about 5 mm to about 20 mm, and typically 10 mm.

[0025]

[0031] The support body 21 can be made of a rigid material. Preferably, the material has a high thermal conductivity and coefficient of thermal expansion close to that of the object being held. Preferably, the material is electrically conductive. Preferably, the material has high hardness. Suitable materials include SiC (silicon carbide), SiSiC (silicon-infiltrated silicon carbide), Si3N4 (silicon nitrite), quartz, and / or various other ceramics and glass-ceramics, such as Zerodur™ glass-ceramic. The support body 21 can be fabricated by selectively removing material from a solid disk of the appropriate material, leaving protruding burls 22. Suitable techniques for removing material include electrical discharge machining (EDM), etching, machining, and / or laser ablation. The support body 21 can also be fabricated by growing burls 22 through a mask. The burls 22 can be grown by a physical vapor deposition process or sputtering, using the same material as the base. The support body 21 can include one or more internal channels (not shown). The support body 21 may include multiple layers bonded together. These layers may be formed of different materials. By way of example only, the support body 21 may include, in order, a layer of SiSiC, a layer of glass, and another layer of SiSiC. Other layer combinations are possible.

[0026]

[0032] As shown in FIG. 2 , the substrate support 20 may include one or more electrodes 26 for electrostatic clamping. A potential difference may be generated to provide an electrostatic clamping force between the substrate W and the substrate support 20, and / or between the substrate support 20 and the substrate stage of the substrate table WT. The electrodes 26 may be encapsulated between dielectric layers (also known as electrically insulating layers) 27, 28. The generated potential difference may be on the order of 10 to 5,000 volts. U.S. Publication No. 2011-0222033 describes a mechanism that uses one or more heaters and temperature sensors to locally control the temperature of a substrate. This publication is incorporated herein by reference in its entirety, and the techniques described therein may be applied to the techniques described herein.

[0027]

[0033] As shown in FIG. 2 , the substrate support 20 can include an electrostatic sheet 25. The electrostatic sheet 25 includes one or more electrodes 26. The electrode 26 can include two halves of a continuous metal film (but spaced apart from the distal ends 23 of the burls 22) deposited at a separation distance to form the positive and negative elements of the electrostatic clamp. The separation distance is not particularly limited. The separation distance can be at least about 20 μm, optionally at least about 50 μm, optionally at least about 100 μm, optionally at least about 200 μm, and optionally at least about 500 μm. The separation distance can be at most about 2 mm, optionally at most about 1 mm, and optionally at most about 500 μm. The separation distance can be about 500 μm. Thus, there can be two electrodes 26. However, the number of electrodes 26 in the electrostatic sheet 25 is not particularly limited and can be one, three, or more. The metal lines of electrode 26 may have a thickness greater than about 20 nm, preferably greater than about 40 nm. The metal lines preferably have a thickness of about 1 μm or less, preferably less than about 500 nm, preferably less than about 200 nm.

[0028]

[0034] The electrodes 26 of the upper electrostatic sheet 25 may be configured to electrostatically clamp the substrate W to the substrate support 20. The electrodes 26 of the lower electrostatic sheet 25 may be configured to electrostatically clamp the substrate support 20 to the remainder of the substrate table WT, for example to the substrate stage.

[0029]

[0035] The material of the support body 21 and the burls 22 can be electrically conductive. For example, the material of the burls 22 can be SiSiC. However, it is not necessary that the material of the support body 21 and the burls 22 be electrically conductive. A ground layer can be provided that electrically connects the distal ends 23 of two or more of the burls 22 (optionally, all of the burls 22) to ground or a common potential. The ground layer can be formed by depositing a relatively thick layer of conductive material. The conductive material is not particularly limited. The conductive material can be Cr or CrN. The deposited layer can then be patterned to form the ground layer. The pattern can include a series of metal lines connecting the distal ends 23 of the burls 22 together. Such a pattern is sometimes referred to as a “Manhattan” pattern. In an alternative configuration, the deposited layer is not patterned. The ground layer or another layer can be disposed to cover the surface of the support body 21 and / or the burls 22. The ground layer or another layer can help smooth the surface to facilitate cleaning.

[0030]

[0036] As shown in FIG. 2, the electrostatic sheet 25 can include an electrode 26 sandwiched between dielectric layers 27, 28. As shown in FIG. 2, the burls 22 and electrostatic sheet 25 can be provided on both major surfaces of the substrate support 20. In an alternative configuration, the burls 22 and electrostatic sheet 25 are provided on only one of the two major surfaces of the substrate support 20. As shown in FIG. 2, the electrostatic sheet 25 can be between the burls 22. For example, as shown in FIG. 2, holes 34 are provided in the electrostatic sheet 25. The holes 34 are located at positions corresponding to the burls 22 of the support body 21. The burls 22 protrude through each hole 34 in the electrostatic sheet 25 such that the electrode 26 sandwiched between the dielectric layers 27, 28 is provided in the area between the burls 22.

[0031]

[0037] 2, the substrate support 20 may include a bonding material 29. The bonding material 29 may have a thickness of at least 100 nm, for example, about 50 μm. The bonding material 29 fixes the position of the electrostatic sheet 25 relative to the support body 21. The bonding material 29 keeps the holes 34 in the electrostatic sheet 25 aligned with the burls 22. The burls 22 may be positioned at the center of each hole 34 in the electrostatic sheet 25.

[0032]

[0038] 2, the bonding material 29 may be formed in discrete portions that are not interconnected. There may be some variation in the thickness of the various portions of bonding material 29. The separate portions of bonding material 29 may have substantially the same thickness as one another.

[0033]

[0039] As mentioned above, the substrate table WT comprises the substrate support 20 and the substrate stage. The substrate stage comprises a recess in which the substrate support 20 is held. The substrate support 20 and the substrate stage may be referred to as the substrate table WT.

[0034]

[0040] The above is a substrate support 20 used in an EUV lithography system. The following describes the substrate configuration in a DUV system.

[0035]

[0041] Figure 3 schematically depicts a lithographic apparatus comprising: an illumination system (also called an illuminator) IL configured to condition a radiation beam B (e.g. UV or DUV radiation), a support structure (e.g. a mask table) MT configured to support a patterning device (e.g. a mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA according to certain parameters, a substrate table WT configured to hold a substrate (e.g. a resist-coated wafer) W, optionally including a substrate support, connected to a second positioner PW configured to accurately position the substrate table WT according to certain parameters, and a projection system PS (e.g. a refractive projection lens system) configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W.

[0036]

[0042] In operation, the illumination system IL receives the radiation beam B from the radiation source SO, for example via the beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic and / or other types of optical components, or any combination thereof, for directing, shaping and / or controlling the radiation. The illuminator IL may be used to condition the radiation beam B so that it has a desired spatial and angular intensity distribution in its cross-section at the plane of the patterning device MA.

[0037]

[0043] The term "projection system" PS as used herein should be interpreted broadly and can encompass various types of projection systems, including refractive optical systems, catadioptric optical systems, anamorphic optical systems, magnetic optical systems, electromagnetic optical systems, and / or electrostatic optical systems, or any combination thereof, as appropriate to the exposure radiation used and / or other factors such as the use of an immersion liquid or a vacuum. Where the term "projection lens" is used herein, it can be considered as synonymous with the more general term "projection system" PS.

[0038]

[0044] The lithographic apparatus is of a type in which at least a part of the substrate W may be covered with an immersion liquid having a relatively high refractive index, e.g. water, so as to fill an immersion space 11 between the projection system PS and the substrate W. This is also known as immersion lithography. Further information about immersion techniques is given in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0039]

[0045] The lithographic apparatus may also be of a type having two or more substrate tables WT (also known as "dual stage") In such a "multi-stage" machine, the substrate tables WT can be used in parallel, and / or a substrate W placed on one substrate table WT can be used to expose a pattern thereon while a substrate W placed on another substrate table WT is being used to perform preparation steps for a subsequent exposure.

[0040]

[0046] In addition to the substrate table WT, the lithographic apparatus may include a measurement stage (not shown). The measurement stage is arranged to hold a sensor and / or a cleaning device. The sensor may be arranged to measure a property of the projection system PS or a property of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning device may be arranged to clean part of the lithographic apparatus, for example part of the projection system PS or part of the system for providing immersion liquid. When the substrate support WT is remote from the projection system PS, the measurement stage may be moved below the projection system PS.

[0041]

[0047] In operation, the radiation beam B is incident on the patterning device MA, e.g., a mask, which is held on the support structure MT, and is patterned according to a pattern (design layout) present on the patterning device MA. After traversing the patterning device MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. Using the second positioner PW and position measurement system IF, the substrate table WT can be accurately moved to position different target portions C at focused and aligned positions in the path of the radiation beam B. Similarly, the first positioner PM, and possibly further position sensors (not explicitly shown in FIG. 1 ), can be used to accurately position the patterning device MA with respect to the path of the radiation beam B. The patterning device MA and substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the illustrated substrate alignment marks P1, P2 occupy dedicated target portions, they may be located in spaces between the target portions. When the substrate alignment marks P1, P2 are located between target portions C, they are known as scribe-lane alignment marks.

[0042]

[0048] For clarity of this description, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes: x, y, and z. Each of the three axes is orthogonal to the other two. Rotation about the x-axis is referred to as Rx rotation. Rotation about the y-axis is referred to as Ry rotation. Rotation about the z-axis is referred to as Rz rotation. The x- and y-axes define a horizontal plane, and the z-axis is vertical. The Cartesian coordinate system does not limit this description and is used for clarity only. Alternatively, another coordinate system, such as a cylindrical coordinate system, could be used to clarify this description. The Cartesian coordinate system could be oriented differently, for example, so that the z-axis has a component along the horizontal plane.

[0043]

[0049] Immersion technology has been introduced into lithography systems to enable improved resolution of smaller features. In an immersion lithography apparatus, a layer of immersion liquid, having a relatively high refractive index, is provided in an immersion space between the apparatus's projection system PS (through which the patterned beam is projected towards the substrate W) and the substrate W. The immersion liquid covers at least the part of the substrate W that is below the final element of the projection system PS. Thus, at least the part of the substrate W on which exposure takes place is immersed in the immersion liquid.

[0044]

[0050] In commercial immersion lithography, the immersion liquid is water. Typically, this water is highly purified distilled water, such as ultrapure water (UPW), commonly used in semiconductor manufacturing facilities. In immersion systems, UPW is often purified and may undergo additional processing steps before being delivered to the immersion space as the immersion liquid. In addition to water, other liquids with high refractive indices can be used as immersion liquids. Examples include hydrocarbons, such as fluorocarbons, and / or aqueous solutions. Additionally, other fluids besides liquids are also contemplated for use in immersion lithography.

[0045]

[0051] The description herein refers to localized immersion, where, during use, the immersion liquid is confined to an immersion space between the final element and a surface facing the final element. The facing surface is either the surface of the substrate W or a surface of the support stage (or substrate table WT or substrate support) that is coplanar with the surface of the substrate W. (Note that in the following text, references to the surface of the substrate W may also or instead refer to the surface of the substrate table WT or substrate support, and vice versa, unless otherwise stated.) The immersion liquid is confined to the immersion space by means of a fluid handling structure IH that is present between the projection system PS and the substrate table WT or substrate support. The immersion space, which is filled by immersion liquid, is smaller in plan than the top surface of the substrate W, and the immersion space is kept substantially stationary relative to the projection system PS while the substrate W and substrate support move below.

[0046]

[0052] Other immersion systems are also envisaged, such as unconfined immersion systems (so-called "all wet" immersion systems) and bath-based immersion systems. In an unconfined immersion system, the immersion liquid covers an area larger than the surface beneath the final element. The liquid outside the immersion space exists as a thin film. The liquid may cover the entire surface of the substrate W, or it may also cover the substrate W and a coplanar substrate support WT. In a bath-based system, the substrate W is completely immersed in a bath of immersion liquid.

[0047]

[0053] The fluid handling structure IH is a structure that supplies immersion liquid to and removes immersion liquid from the immersion space, thereby confining the immersion liquid to the immersion space. It includes features that are part of a fluid supply system. An arrangement disclosed in PCT Patent Application Publication No. WO 99 / 49504 is an early fluid handling structure that includes pipes that supply or remove immersion liquid from the immersion space and that move in response to relative movement of a stage below the projection system PS. In more recent designs, the fluid handling structure extends along at least part of the boundary of the immersion space between the final element of the projection system PS and the substrate support WT or substrate W, so as to partially define the immersion space.

[0048]

[0054] The fluid handling structure IH may have a variety of selected functions, each resulting from corresponding features that enable the fluid handling structure IH to achieve that function. The fluid handling structure IH may be referred to by a number of different terms, each describing a function, for example barrier member, seal member, fluid supply system, fluid removal system, liquid confinement structure, etc.

[0049]

[0055] Immersion liquid may be used as the immersion fluid, in which case the fluid handling structure IH may be a liquid handling system. With reference to the above description, references in this paragraph to features defined in terms of a fluid may be understood to include features defined in terms of a liquid.

[0050]

[0056] The 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. To reach the substrate W, the path of the radiation beam B passes from the projection system PS through immersion liquid that is confined by a fluid handling structure IH between the projection system PS and the substrate W. The projection system PS has a lens element at the end of the beam path, which is in contact with the immersion liquid. This lens element in contact with the immersion liquid may be referred to as the "last lens element" or "final element". The final element is at least partly surrounded by a fluid handling structure IH. The fluid handling structure IH may confine immersion liquid below the final element and above a facing surface.

[0051]

[0057] As shown in Figure 3, the lithographic apparatus includes a controller 500. The controller 500 is configured to control the substrate table WT.

[0052]

[0058] Figure 4 shows part of a lithographic apparatus that is not in accordance with the present invention, but is useful for illustrating features of the present invention. The arrangement shown in Figure 4 and described below can be applied to the lithographic apparatus described above and shown in Figure 3. Figure 4 shows a cross-section of a substrate support 20 and a substrate W. The substrate table WT of Figure 3 includes the substrate support 20 and a substrate stage (not shown) configured to support the substrate support 20, or the substrate support 20 itself may be integral with the substrate table WT to form a single piece. In an embodiment, the substrate support 20 includes one or more conditioning channels 61 of a thermal conditioner 60, which will be described in more detail below. A gap 5 exists between the edge of the substrate W and the edge of the substrate support 20. When the edge of the substrate W is being imaged, or at other times, for example when the substrate W is first moved under the projection system PS (as described above), the immersion space, which is filled with liquid by (for example) the fluid handling structure IH, will at least partly pass over the gap 5 between the edge of the substrate W and the edge of the substrate support 20. As a result, liquid from the immersion space may enter the gap 5 .

[0053]

[0059] The substrate W is held by a support body 21 (e.g. a pimple or burl table) which includes one or more burls 41 (i.e. protrusions from its surface). The support body 21 is an example of an object holder. Another example of an object holder is the support structure MT. Negative pressure applied between the substrate W and the substrate support 20 helps to ensure that the substrate W is held firmly in place. However, if immersion liquid gets between the substrate W and the support body 21, this can cause problems, particularly when unloading the substrate W.

[0054]

[0060] To deal with immersion liquid entering the gap 5, at least one drain 10, 12 is provided at the edge of the substrate W to remove immersion liquid that enters the gap 5. Although two drains 10, 12 are illustrated in Figure 4, there may be only one drain, or there may be three or more drains. Each of the drains 10, 12 is annular so as to surround the entire periphery of the substrate W.

[0055]

[0061] The main function of the first drain 10 (radially outward from the edge of the substrate W / support body 21) is to help prevent gas bubbles from entering the immersion space where the liquid of the fluid handling structure IH is present. Such gas bubbles could adversely affect imaging of the substrate W. The first drain 10 is present to help avoid gas in the gap 5 escaping into the immersion space of the fluid handling structure IH. If gas escapes into the immersion space, this could result in gas bubbles floating in the immersion space. Such gas bubbles could lead to imaging errors if they were in the path of the projection beam. The first drain 10 is configured to remove gas from the gap 5 between the edge of the substrate W and the edge of a recess in the substrate support 20 in which the substrate W is located. The edge of the recess in the substrate support 20 may be defined by a cover ring 101, which is optionally separate from the support body 21 of the substrate support 20. The cover ring 101 may have the shape of a ring in plan and surrounds the outer edge of the substrate W. The first drain 10 extracts mainly gas and also a small amount of immersion liquid.

[0056]

[0062] A second drain 12 (radially inward of the edge of the substrate W / support body 21) is provided to help prevent liquid flowing underneath the substrate W from the gap 5 from interfering with efficient release of the substrate W from the substrate table WT after imaging. The provision of the second drain 12 reduces or eliminates problems that can be caused by liquid flowing underneath the substrate W.

[0057]

[0063] As shown in Figure 4, in one embodiment, the lithographic apparatus includes a first extraction channel 102 for the two-phase flow to pass through. The first extraction channel 102 is formed in the support body 21. The first and second drains 10, 12 are provided with respective openings 107, 117 and respective extraction channels 102, 113. The extraction channels 102, 113 are in fluid communication with the respective openings 107, 117 via respective passages 103, 114.

[0058]

[0064] As shown in Figure 4, the cover ring 101 has a top surface, which extends circumferentially around the substrate W on the support body 21. When the lithographic apparatus is in use, the fluid handling structure IH moves relative to the substrate support 20. During this relative movement, the fluid handling structure IH moves across the gap 5 between the cover ring 101 and the substrate W. In one embodiment, this relative movement occurs by the substrate support 20 moving below the fluid handling structure IH. In an alternative embodiment, this relative movement occurs by the fluid handling structure IH moving above the substrate support 20. In another alternative embodiment, this relative movement is provided by both the substrate support 20 moving below the fluid handling structure IH and the fluid handling structure IH moving above the substrate support 20. In the following description, movement of the fluid handling structure IH is used to refer to the relative movement of the fluid handling structure IH with respect to the substrate support 20.

[0059]

[0065] In both EUV and DUV systems, the substrate W held on the substrate support 20 may warp, i.e., the shape of the substrate W may be deformed so that it is not perfectly planar. Typical shape deformations of the substrate W are bowl-shaped and umbrella-shaped. Such shape deformations of the substrate W may be at least partially corrected by moving a portion of the substrate W in the z-direction, either closer to or farther from the substrate support 20. However, there is currently no known technique for quickly performing such movements outside the final row of burrs. Therefore, shape deformations at the periphery or edge region of the substrate W may be a substantial source of overlay errors.

[0060]

[0066] The embodiments solve the above problems by providing a novel method for moving the periphery of the substrate W in the z-direction to at least partially correct the shape deformation of the substrate W.

[0061]

[0067] FIG. 5 shows a schematic diagram of a substrate support mechanism used in an EUV system according to a first embodiment.

[0062]

[0068] The substrate support mechanism includes a substrate support 20 and a substrate shaping system 700. The substrate support 20 may be the substrate support 20 described above with reference to Figures 1 and 2. The substrate support 20 may provide a support surface, which may be a substantially planar support surface, for the substrate W. The support surface 24 may be provided by the distal ends 23 of the plurality of burls 22, as described above with reference to the support surface 24 in Figure 2.

[0063]

[0069] The substrate shaping system 700 includes at least one substrate shaping device 701. Each substrate shaping device 701 is positioned to apply an electrostatic force to the periphery of the substrate W when the substrate W is provided on a support surface. Each substrate shaping device 701 may include an electrode mechanism configured to generate the electrostatic force that the substrate shaping device 701 applies to the substrate W. Each electrode mechanism may include a ground electrode 706 and a force-generating electrode 702. As shown in FIG. 5 , the ground electrode 706 may be provided on an upper surface of a portion of the substrate shaping device 701 or embedded therein. The force-generating electrode 702 may be provided on a lower surface of a portion of the substrate shaping device 701 or embedded therein. The force-generating electrode 702 may be positioned above the substrate W such that application of the electrostatic force moves the substrate W away from the substrate support 20. The electrostatic force applied to the substrate W may be generated by a potential difference between the force-generating electrode 702 and the substrate W. The substrate support mechanism may also include a controller (not shown) configured to control the magnitude of the potential difference between the ground electrode 706 and the force-generating electrode 702. The magnitude of the electrostatic force applied by the force-generating electrode 702 may depend on the potential difference between the ground electrode 706 and the force-generating electrode 702. The controller can thereby control the magnitude of the electrostatic force applied to the substrate W.

[0064]

[0070] The substrate shaping system 700 may include a plurality of substrate shaping devices 701. In a plan view, the plurality of substrate shaping devices 701 may be arranged around the support surface. The plurality of substrate shaping devices 701 may be evenly spaced around the circumference of the support surface. Each substrate shaping device 701 may be positioned to apply an electrostatic force to a different segment of the substrate W. The substrate shaping devices 701 may be individually controllable. The substrate shaping devices 701 may thereby be positioned to individually apply an electrostatic force to different portions of the periphery of the substrate W.

[0065]

[0071] Each substrate shaping device 701 may be movable between a first position and a second position. In the first position, the substrate shaping device 701 may be positioned near and above the outer periphery of the substrate W. The electrostatic force is a short-range force. Positioning the substrate shaping device 701 near and above the outer periphery of the substrate W ensures that the electrostatic force is applied to the outer periphery of the substrate W. The central region of the substrate W is substantially unaffected by the electrostatic force due to its large distance from the force-generating electrode 702.

[0066]

[0072] When each substrate shaping device 701 is in the first position, it may be difficult to load the substrate W onto the substrate support 20 due to the risk of collision between the substrate W and at least one of the substrate shaping devices. To overcome this problem, each substrate shaping device 701 may be movable to a second position in which each substrate shaping device 701 is positioned further away from the midpoint of the substrate support 20. When each substrate shaping device 701 is in the second position, the substrate W can be easily positioned on the substrate support 20. Thus, each substrate shaping device 701 may be moved to the second position during loading and unloading of the substrate W, and moved to the first position once the substrate W has been loaded onto the substrate support 20.

[0067]

[0073] 5 schematically illustrates a substrate shaping device 701 in a first position. The substrate shaping device 701 may be constituted by a substantially L-shaped portion of the substrate shaping system 700. When in the first position, the substrate shaping device 701 may be configured to overhang the periphery of the substrate W. There may be an xy separation distance 705, which may be referred to as a lateral gap, between the edge of the substrate W and the vertical legs of the substrate shaping device 701. There may be a z separation distance 704, which may be referred to as a vertical gap, between the top surface of the substrate W at the periphery of the substrate W and the overhanging substrate shaping device 701.

[0068]

[0074] To move between the first and second positions, each substrate shaping device 701 may be movable relative to the substrate support 20 in a direction parallel to the plane of the support surface, i.e., in a direction that increases or decreases the xy separation distance 705. Additionally or alternatively, each substrate shaping device 701 may be movable relative to the substrate support 20 in a direction perpendicular to the plane of the support surface, i.e., in a direction that increases or decreases the z separation distance 704. The substrate shaping system 700 may include one or more piezo actuators (not shown) for moving each substrate shaping device 701 relative to the substrate support 20.

[0069]

[0075] When each substrate shaping device 701 is located in a first position, the force-generating electrodes 702 are positioned such that the electrostatic force applied to the substrate W is perpendicular to the plane of the support surface and includes a component directed to move the substrate W away from the support surface. The force-generating electrodes 702 may be positioned directly above the top surface of the substrate W at the periphery of the substrate W so that the electrostatic force is directed at an angle of approximately 90 degrees relative to the plane of the support surface. Alternatively, the force-generating electrodes 702 may be positioned laterally offset above the top surface of the substrate W at the periphery of the substrate W so that the electrostatic force is directed at an angle of approximately 80 degrees relative to the plane of the support surface.

[0070]

[0076] The first position of each substrate shaping device 701 can be changed depending on the actual shape of the substrate W currently disposed on the substrate support 20. The type of substrate shape deformation that may need to be corrected may be bowl-shaped or umbrella-shaped. Furthermore, the degree of substrate shape deformation varies from substrate W to substrate. If the first position of each substrate shaping device was a fixed, predetermined position used for all substrates W, each substrate shaping device 701 may not be positioned sufficiently close to the surface of the substrate W due to variations in the actual shape of the substrate W. Therefore, to ensure that the first position of each substrate shaping device 701 is sufficiently close to the surface of the substrate W, the first position of each substrate shaping device 701 can be determined depending on the actual shape of the substrate W currently disposed on the substrate support 20.

[0071]

[0077] To determine a suitable first position for each substrate shaping device 701, the substrate shaping system 700 may include a sensor system (not shown) configured to determine the relative position of each substrate shaping device 701 and the substrate W. For example, the sensor system may determine the magnitude of the xy separation distance 705 and / or the z separation distance 704. The sensor system may include one or more capacitors and / or light sources for determining / measuring the magnitude of the xy separation distance 705 and / or the z separation distance 704.

[0072]

[0078] An appropriate first position for each substrate shaping device 701 can be determined as a position where the magnitude of the xy-direction separation distance 705 and / or the z-direction separation distance 704 is within a predetermined range. For example, the movement of each substrate shaping device 701 can be controlled by a controller such that the xy-direction separation distance 705 is 10 μm or less and the z-direction separation distance 704 is 10 μm or less.

[0073]

[0079] The substrate shaping system 700 described above applies an electrostatic force to the outer periphery of the substrate W, which moves the substrate W away from the substrate support 20 .

[0074]

[0080] Embodiments also include techniques for applying an electrostatic force to the periphery of the substrate W that moves the substrate W towards the substrate support 20.

[0075]

[0081] As shown in FIG. 5 , an embodiment includes providing one or more separate force-generating electrodes 703. Each of the one or more separate force-generating electrodes 703 can be provided on or embedded within the substrate support 20 and / or a surrounding structure of the substrate support 20. The one or more separate force-generating electrodes 703 can be positioned such that when the substrate W is loaded onto the substrate support 20, the one or more separate force-generating electrodes 703 are disposed below the outer periphery of the substrate W. There can be multiple separate force-generating electrodes 703. In plan view, the multiple separate force-generating electrodes 703 can be disposed around the support surface. The multiple separate force-generating electrodes 703 can be evenly spaced around the circumference of the support surface. Each separate force-generating electrode 703 can be positioned to apply an electrostatic force to a different segment of the substrate W. The multiple separate force-generating electrodes 703 can be individually controllable. The multiple separate force-generating electrodes 703 can thereby be positioned to individually apply an electrostatic force to different portions of the outer periphery of the substrate W.

[0076]

[0082] Each of the one or more further force-generating electrodes 703 may be electrically isolated. The substrate support 20 and / or the surrounding structure of the substrate support 20 may be electrically grounded. Each of the one or more further force-generating electrodes 703 may generate a potential difference between the force-generating electrode 703 and ground. Each further force-generating electrode 703 may apply an electrostatic force to the substrate W that depends on this potential difference. A controller (not shown) may control the electrostatic force applied by each of the one or more further force-generating electrodes 703 by controlling each potential difference.

[0077]

[0083] Thus, one or more further force-generating electrodes 703 can generate an electrostatic force to move the substrate W towards the substrate support 20 .

[0078]

[0084] Advantageously, the first embodiment provides a technique for moving the periphery of the substrate W towards and / or away from the plane of the support surface of the substrate W. This allows topographical deformations at the edge of the substrate W to be at least partially corrected by applying a force to the substrate W to correct the deformations. The applied force may be substantially perpendicular to the support surface of the substrate W. This avoids applying substantial lateral forces to the substrate W. The use of electrostatic forces is preferable to contacting the substrate W and applying a mechanical force directly, which may cause damage to the substrate W.

[0079]

[0085] According to a second embodiment, a technique is provided for altering the shape of a substrate W in a DUV system to at least partially compensate for deformation of the substrate W. Like the first embodiment, the second embodiment also applies an electrostatic force to the periphery of the substrate W using force-generating electrodes.

[0080]

[0086] In a DUV system, an immersion fluid is present between at least part of the surface of the substrate W and the projection system PS. If the immersion fluid flows into the region between the force-generating electrodes and the substrate W, the immersion fluid substantially attenuates the electrostatic forces applied to the substrate W. A second embodiment includes at least one seal to ensure that substantially no immersion fluid is present between each force-generating electrode and the substrate W.

[0081]

[0087] FIG. 6 shows a schematic diagram of a substrate support mechanism used in a DUV system according to a second embodiment.

[0082]

[0088] The substrate support mechanism includes a substrate support 20 and a substrate shaping system 800. The substrate support 20 may be the substrate support 20 described above with reference to Figures 3 and 4. The substrate support 20 may provide a support surface, which may be a substantially planar support surface, for the substrate W. The support surface may be defined by the distal ends of a plurality of burls 41.

[0083]

[0089] The substrate shaping system 800 includes at least one substrate shaping device 802 and at least one base 801. Each substrate shaping device 802 is positioned to apply an electrostatic force to the periphery of the substrate W when the substrate W is provided on a support surface. Each substrate shaping device 802 may include an electrode mechanism configured to generate the electrostatic force that the substrate shaping device 802 applies to the substrate W. Each electrode mechanism may include a ground electrode 803 and at least one force-generating electrode 804, 805. As shown in FIG. 6 , each ground electrode 803 may be provided on the top surface of or embedded within a portion of the substrate shaping device 802.

[0084]

[0090] 6 shows an upper force-generating electrode 804 and a lower force-generating electrode 805. The upper force-generating electrode 804 can be positioned directly above the lower force-generating electrode 805. The upper force-generating electrode 804 can be positioned directly below the ground electrode 803. Both the upper force-generating electrode 804 and the lower force-generating electrode 805 can be positioned near the substrate-facing edge of the substrate shaping device 802. The upper force-generating electrode 804 can be provided on an upper surface of, or embedded within, a portion of the substrate shaping device 802. The lower force-generating electrode 805 can be provided on a lower surface of, or embedded within, a portion of the substrate shaping device 802.

[0085]

[0091] A controller (not shown) can generate a potential difference between the ground electrode 803 and the upper force-generating electrode 804 and / or the lower force-generating electrode 805. As a result, an electrostatic force is applied to the substrate W by the upper force-generating electrode 804 and / or the lower force-generating electrode 805. The upper force-generating electrode 804 can be positioned farther from the support surface than the top surface of the substrate W. The lower force-generating electrode 804 can be positioned closer to the support surface than the bottom surface of the substrate W. The electrostatic forces applied by the upper force-generating electrode 804 and the lower force-generating electrode 805 to the outer periphery of the substrate W can include both x, y and z direction components. The z direction component of the electrostatic force applied by the upper force-generating electrode 804 can act to move the outer periphery of the substrate W away from the support surface. The z direction component of the electrostatic force applied by the lower force-generating electrode 804 can act to move the outer periphery of the substrate W towards the support surface. Thus, the upper force-generating electrode 804 and the lower force-generating electrode 805 can be used to apply a force to the outer periphery of the substrate W that moves the outer periphery of the substrate W away from or towards the support surface. As described in the first embodiment, the substrate support mechanism may include a controller configured to control the magnitude of the potential difference between the ground electrode 803 and the upper force-generating electrode 804 and / or the lower force-generating electrode 805.

[0086]

[0092] In a preferred implementation of the second embodiment, the upper force-generating electrode 804 is positioned such that the direction of the electrostatic force applied by the upper force-generating electrode 804 to the outer periphery of the substrate W is at an angle of about 80 degrees relative to the plane of the support surface, and the lower force-generating electrode 805 is preferably positioned such that the direction of the electrostatic force applied by the lower force-generating electrode 805 to the outer periphery of the substrate W is at an angle of about 80 degrees relative to the plane of the support surface.

[0087]

[0093] The ground electrode 803 may be at least partially on the top surface of the substrate shaping device 802. The ground electrode 803 may be substantially coplanar with the top surface of the substrate W.

[0088]

[0094] In this embodiment, there is a seal 807 that covers the substrate shaping device 802 and at least a portion of the substrate W. The seal 807 may extend in the x and y directions from above the substrate shaping device 802 to above the top surface of the substrate W. The seal 807 may be a liquid seal that substantially prevents immersion fluid on the top surface of the substrate W from flowing over the edge of the substrate W. The seal 807 ensures that substantially no immersion fluid is present between the periphery of the substrate W and the upper force generating electrode 804 or the lower force generating electrode 805.

[0089]

[0095] The substrate shaping system 800 may include a plurality of substrate shaping devices 802. In a plan view, the plurality of substrate shaping devices 802 may be arranged around the circumference of the support surface. The plurality of substrate shaping devices 802 may be evenly spaced around the circumference of the support surface. Each substrate shaping device 802 may be positioned to apply an electrostatic force to a different segment of the substrate W. The substrate shaping devices 802 may be individually controllable. The substrate shaping devices 802 may thereby be positioned to individually apply an electrostatic force to different portions of the periphery of the substrate W.

[0090]

[0096] As described in the first embodiment, each substrate shaping device 802 may be movable between a first position and a second position. In the first position, the substrate shaping device 802 may be positioned near the outer periphery of the substrate W so as to apply an electrostatic force to the outer periphery of the substrate W. The second position of each substrate shaping device 802 may be positioned further away from the midpoint of the substrate support 20 to allow the substrate W to be easily positioned on the substrate support 20. Each substrate shaping device 802 may be moved to the second position during loading and unloading of the substrate W, and moved to the first position once the substrate W has been loaded onto the substrate support 20.

[0091]

[0097] 6 shows a schematic representation of the substrate shaping device 802 in a first position. There is an xy separation distance 806, which may be referred to as a lateral gap, between the edge of the substrate W and the substrate-facing edge of the substrate shaping device 802.

[0092]

[0098] To move between the first and second positions, each substrate shaping device 802 may be movable relative to the substrate support 20 in a direction parallel to the plane of the support surface, i.e., in a direction that increases or decreases the xy separation distance 806. Each substrate shaping device 802 may be disposed on a base 801 that includes one or more piezo actuators (not shown) for moving the substrate shaping device 802 relative to the substrate support 20.

[0093]

[0099] As described in the first embodiment, to determine a suitable first position for each substrate shaping device 802, the substrate shaping system 800 may include a sensor system (not shown) configured to determine the relative position of each substrate shaping device 802 and the substrate W. For example, the sensor system may determine the magnitude of the x-y separation distance 806. The sensor system may include one or more capacitors and / or light sources for determining / measuring the magnitude of the x-y separation distance 806. The suitable first position for each substrate shaping device 802 may be determined as a position where the magnitude of the x-y separation distance 806 is within a predetermined range. For example, the movement of each substrate shaping device 802 may be controlled by a controller so that the x-y separation distance 806 is 10 μm or less.

[0094]

[0100] FIG. 7 shows a schematic of a portion of a seal 807 according to one embodiment. The seal 807 may be a mechanical edge seal (MES). The seal 807 may include a groove 901 in its substrate-facing surface. Immersion fluid, which may be water, may be present in a fluid region 903 above the substrate W. Due to surface tension, a meniscus 902 of the immersion fluid forms at the edge of the groove 901, preventing the immersion fluid from flowing further along the length of the seal 807. The groove 901 thus provides a capillary stop. Advantageously, the seal 807 does not physically contact the substrate W. Furthermore, the presence of the seal 807 reduces the amount of immersion fluid flowing over the edge of the substrate W, thereby reducing both the heat load and the heat load variation on each substrate W. Additionally or alternatively, gas may be supplied to an area below the periphery of the substrate W to increase the gas pressure. The gas overpressure may reduce or prevent the flow of immersion liquid over the edge of the substrate W.

[0095]

[0101] The seal 807 may be fixed or movable. The stationary seal 807 may be a single annular structure that, in plan, covers the entire circumference of the substrate W. When a stationary seal 807 is used, the seal 807 may maintain its position relative to the substrate W as each substrate shaping device 802 moves between its first and second positions. A separate mechanism may be used to position the stationary seal 807 above the substrate W after the substrate W has been loaded onto the substrate support 20. The same mechanism may be used to move the stationary seal 807 from above the substrate W before the substrate W is unloaded.

[0096]

[0102] Alternatively, a seal 807 may be fixed to each substrate shaping device 802 to provide a movable seal 807. Each seal 807 may have a shape that is a truncated sector of a circle in a plan view. Each seal 807 may move with the substrate shaping device 802 to which it is fixed as the substrate shaping devices 802 move between the first position and the second position. When all of the substrate shaping devices 802 are in the first position, the seals 807 contact each other and may combine to form an annular seal around the circumference of the substrate W in a plan view.

[0097]

[0103] As in the first embodiment, in the second embodiment, one or more additional force-generating electrodes 808 may be provided on or embedded within the substrate support 20 and / or the surrounding structure of the substrate support 20. The one or more additional force-generating electrodes 808 may be positioned such that when the substrate W is loaded onto the substrate support 20, the one or more additional force-generating electrodes 808 are disposed below the outer periphery of the substrate W. There may be multiple additional force-generating electrodes 808. In plan view, the multiple additional force-generating electrodes 808 may be disposed around the support surface. The multiple additional force-generating electrodes 808 may be evenly spaced around the circumference of the support surface. Each additional force-generating electrode 808 may be positioned to apply an electrostatic force to a different segment of the substrate W. The multiple additional force-generating electrodes 808 may be individually controllable. The multiple additional force-generating electrodes 808 may thereby be positioned to individually apply an electrostatic force to different parts of the outer periphery of the substrate W.

[0098]

[0104] Each of the one or more further force-generating electrodes 808 may be electrically isolated. The substrate support 20 and / or the surrounding structure of the substrate support 20 may be electrically grounded. Each of the one or more further force-generating electrodes 808 may create a potential difference between the force-generating electrode 808 and ground. Each further force-generating electrode 808 may apply an electrostatic force to the substrate W that depends on this potential difference. A controller may control the electrostatic force applied by each of the one or more further force-generating electrodes 808 by controlling each potential difference.

[0099]

[0105] Thus, one or more further force-generating electrodes 808 can generate an electrostatic force to move the substrate W towards the substrate support 20 .

[0100]

[0106] The above-described embodiments provide a novel technique for at least partially correcting shape deformation of the substrate W. To reduce the shape deformation of the substrate W, an electrostatic force can be applied to the outer periphery of the substrate W to change the shape of the substrate W. The technique of the embodiments can be applied to both EUV and DUV.

[0101]

[0107] The embodiments include many modifications and variations to the techniques described above.

[0102]

[0108] In both the first and second embodiments, force-generating electrodes 703, 808 provided on the surface of or embedded within the substrate support 20 and / or surrounding structure of the substrate support 20 are optional, nevertheless allowing at least partial correction of umbrella deformation of the substrate W.

[0103]

[0109] In the second embodiment, the provision of the lower force-generating electrode 805 is optional. The electrode arrangement of each substrate shaping device 802 may include only the ground electrode 803 and the upper force-generating electrode 804.

[0104]

[0110] The use of a capillary stop in the seal 807 is optional. The seal 807 may alternatively contact the top surface of the substrate W.

[0105]

[0111] The substrate shaping device 701 shown in Figure 5 may be adapted so that the end of the portion that overhangs the substrate W includes a groove (not shown). The groove may be similar to the groove 901 described with reference to Figure 7 and may therefore be a capillary stop. In vacuum systems such as EUV systems, no liquid is present on the surface of the substrate W and therefore no capillary stop is required. However, providing the substrate shaping device 701 with a capillary stop allows the same substrate shaping device 701 to be used in both EUV and DUV systems.

[0106]

[0112] The burl arrangement shown in Figure 2 is exemplary. Embodiments include arrangements in which the number of burls 22, 41 protruding from the surface facing the substrate W is significantly greater than the number of burls pointing away from the substrate W.

[0107]

[0113] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be appreciated that the lithographic apparatus described herein may have other applications, including the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0108]

[0114] Although particular reference is made herein to embodiments of the invention in the context of lithography apparatus, embodiments of the invention may also be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatus may be generally referred to as lithography tools. Such lithography tools may use vacuum or ambient (non-vacuum) conditions.

[0109]

[0115] Although particular reference has been made to the use of embodiments of the present invention in the context of object inspection and / or optical lithography, it will be appreciated that the present invention is not limited to these contexts and may be used in other applications, such as imprint lithography, where circumstances permit.

[0110]

[0116] Embodiments include the following numbered clauses: 1. A substrate support mechanism configured to support a substrate, comprising: a substrate support providing a substantially planar support surface for a substrate; a substrate shaping system including one or more substrate shaping devices; each substrate shaping device is movable relative to the substrate support; The substrate support mechanism, wherein each substrate shaping device is positioned to apply an electrostatic force to a periphery of the substrate when the substrate is provided on the support surface. 2. A substrate support arrangement as described in clause 1, wherein each substrate shaping device is arranged to move relative to the substrate support in a direction parallel to the plane of the support surface. 3. A substrate support arrangement according to clause 1 or 2, wherein each substrate shaping device is arranged to move relative to the substrate support in a direction perpendicular to the plane of the support surface. 4. A substrate support mechanism according to any one of clauses 1 to 3, wherein the substrate shaping system includes a plurality of substrate shaping devices, and in plan view, the plurality of substrate shaping devices are arranged around the support surface. 5. Further comprising one or more piezo actuators; 5. A substrate support arrangement according to any of clauses 1 to 4, wherein each piezo actuator is arranged to move at least one substrate shaping device relative to the substrate support. 6. A substrate support mechanism according to any of clauses 1 to 5, wherein each substrate shaping device includes an electrode mechanism configured to generate an electrostatic force applied by the substrate shaping device. 7. The electrode mechanism includes a ground electrode and a force-generating electrode; 7. The substrate support mechanism of clause 6, wherein the ground electrode and the force-generating electrode are arranged such that when the substrate is provided on the support surface, an electrostatic force is generated between the force-generating electrode and the outer periphery of the substrate. 8. The substrate support mechanism of clause 7, further comprising a controller arranged to control the magnitude of the electrostatic force applied by the substrate shaping devices by controlling the magnitude of the potential difference between the ground electrode and the force-generating electrode of each substrate shaping device. 9. A substrate support arrangement as described in clause 7 or 8, wherein the force-generating electrodes are arranged such that when a substrate is provided on the support surface, the electrostatic force exerted by each substrate shaping device includes a component that is perpendicular to the plane of the support surface and oriented to move the substrate away from the support surface. 10. A substrate support mechanism according to any of clauses 7 to 9, wherein the force-generating electrodes are arranged such that when a substrate is provided on the support surface, the electrostatic force exerted by each substrate shaping device is directed at an angle of approximately 90 degrees relative to the plane of the support surface. 11. A substrate support mechanism according to any of clauses 7 to 9, wherein the force-generating electrodes are arranged such that when a substrate is provided on the support surface, the electrostatic force exerted by each substrate shaping device is directed at an angle of approximately 80 degrees relative to the plane of the support surface. 12. A substrate support arrangement according to any of clauses 7 to 11, wherein the force-generating electrodes of each substrate shaping device are embedded within the substrate shaping device. 13. A substrate support arrangement according to any of clauses 7 to 12, wherein the ground electrode of each substrate shaping device is located on an upper surface of the substrate shaping device. 14. Each substrate shaping device includes two or more force-generating electrodes; 14. A substrate support mechanism as described in any of clauses 7 to 13, wherein at least one force-generating electrode is arranged such that when a substrate is provided on the support surface, the electrostatic force applied by each substrate shaping device includes a component that is perpendicular to the plane of the support surface and is oriented to move the substrate towards the support surface. 15. A substrate support arrangement according to any of clauses 1 to 14, wherein when the substrate is provided on the support surface, a lateral gap is formed between an edge of the substrate and an edge of each substrate shaping device. 16. The substrate support mechanism of clause 15, further comprising a sensor system configured to measure the size of each lateral gap. 17. The substrate support mechanism of clause 16, further comprising a controller configured to control movement of each substrate shaping device in response to the measured size of each lateral gap. 18. The substrate support mechanism of clause 17, wherein the controller is configured to control movement of each substrate shaping device such that each lateral gap is 10 μm or less. 19. A substrate support arrangement according to any of clauses 15 to 18, wherein an upper surface of each substrate shaping device is substantially coplanar with an upper surface of the substrate when the substrate is provided on the support surface. 20. Further comprising one or more seals; 20. The substrate support mechanism of claim 19, wherein each seal is positioned such that when a substrate is provided on the support surface, each seal spans a lateral gap formed between an edge of the substrate and an edge of each substrate shaping device. 21. A substrate support arrangement as described in clause 20, wherein each seal is positioned so as not to contact the substrate when the substrate is provided on the support surface. 22. A substrate support arrangement according to clause 20 or 21, wherein each seal comprises a capillary stop when the substrate is provided on the support surface. 23. A substrate support mechanism according to any of clauses 1 to 14, wherein when a substrate is provided on the support surface, each substrate shaping device moves such that a vertical gap is formed between an upper surface of the substrate and a lower surface of each substrate shaping device. 24. The substrate support mechanism of clause 23, further comprising a sensor system configured to measure the size of each vertical gap. 25. The substrate support mechanism of clause 24, further comprising a controller configured to control movement of each substrate shaping device in response to the measured size of each vertical gap. 26. The substrate support mechanism of clause 25, wherein the controller is configured to control movement of each substrate shaping device such that each vertical gap is 10 μm or less. 27. Further comprising one or more additional force-generating electrodes embedded within the substrate support and / or surrounding structure of the substrate support; the one or more further force-generating electrodes are arranged such that when the substrate is provided on the support surface, each of the one or more further force-generating electrodes is positioned to apply an electrostatic force to a periphery of the substrate; 27. A substrate support mechanism according to any preceding clause, wherein each electrostatic force includes a component that is perpendicular to the plane of the support surface and directed to move the substrate towards the support surface. 28. A substrate support arrangement as described in clause 27, wherein there are a plurality of further force-generating electrodes embedded within the substrate support and / or surrounding structure of the substrate support, and in plan view the plurality of further force-generating electrodes are arranged around the support surface. 29. A lithographic apparatus comprising a substrate support arrangement according to any one of clauses 1 to 28. 30. A method of changing the shape of a substrate, comprising: loading a substrate onto a substrate support of a substrate support mechanism according to any one of clauses 1 to 28; applying an electrostatic force to the outer periphery of the substrate; A method comprising:

[0111]

[0117] While specific embodiments of the invention have been described above, it will be apparent that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set forth below.

Claims

1. A substrate support mechanism configured to support a substrate, comprising: a substrate support providing a substantially planar support surface for a substrate; a substrate shaping system including one or more substrate shaping devices; each substrate shaping device is movable relative to the substrate support; The substrate support mechanism, wherein each substrate shaping device is positioned to apply an electrostatic force to a periphery of the substrate when the substrate is provided on the support surface.

2. 2. The substrate support mechanism of claim 1, wherein each substrate shaping device is arranged to move relative to the substrate support in a direction parallel to the plane of the support surface, and / or each substrate shaping device is arranged to move relative to the substrate support in a direction perpendicular to the plane of the support surface.

3. 3. The substrate support mechanism of claim 1, wherein the substrate shaping system includes a plurality of substrate shaping devices, in a plan view, arranged around the support surface, and / or further includes one or more piezoelectric actuators, each piezoelectric actuator arranged to move at least one substrate shaping device relative to the substrate support, and / or each substrate shaping device includes an electrode mechanism configured to generate the electrostatic force applied by the substrate shaping device.

4. the electrode mechanism includes a ground electrode and a force-generating electrode; 4. The substrate support mechanism of claim 3, wherein the ground electrode and the force-generating electrode are arranged such that when a substrate is provided on the support surface, the electrostatic force is generated between the force-generating electrode and the outer periphery of the substrate.

5. 5. The substrate support mechanism of claim 4, further comprising: a controller arranged to control the magnitude of the electrostatic force applied by the substrate shaping device by controlling the magnitude of the potential difference between the ground electrode and the force-generating electrode of each substrate shaping device; and / or the force-generating electrodes are arranged such that, when a substrate is provided on the support surface, the electrostatic force applied by each substrate shaping device includes a component that is perpendicular to the plane of the support surface and directed to move the substrate away from the support surface; and / or the force-generating electrodes are arranged such that, when a substrate is provided on the support surface, the electrostatic force applied by each substrate shaping device is directed at an angle of approximately 90 degrees relative to the plane of the support surface; and / or the force-generating electrodes are arranged such that, when a substrate is provided on the support surface, the electrostatic force applied by each substrate shaping device is directed at an angle of approximately 80 degrees relative to the plane of the support surface.

6. the force-generating electrode of each substrate shaping device is embedded within the substrate shaping device, and / or the ground electrode of each substrate shaping device is located on a top surface of the substrate shaping device, and / or each substrate shaping device includes two or more force-generating electrodes; 6. The substrate support mechanism of claim 5, wherein at least one force-generating electrode is arranged such that when a substrate is provided on the support surface, the electrostatic force exerted by each substrate shaping device includes a component that is perpendicular to the plane of the support surface and oriented to move the substrate towards the support surface.

7. The substrate support mechanism of claim 1 , wherein when a substrate is provided on the support surface, a lateral gap is formed between an edge of the substrate and an edge of each substrate shaping device.

8. 8. The substrate support mechanism of claim 7, further comprising a sensor system configured to measure the size of each lateral gap, and preferably further comprising a controller configured to control the movement of each substrate shaping device in accordance with the measured size of each lateral gap, and preferably wherein the controller is configured to control the movement of each substrate shaping device so that each lateral gap is 10 μm or less, and / or wherein when a substrate is provided on the support surface, an upper surface of each substrate shaping device is substantially flush with an upper surface of the substrate.

9. further comprising one or more seals; 9. The substrate support mechanism of claim 8, wherein each seal is positioned such that when a substrate is provided on the support surface, each seal spans the lateral gap formed between the edge of the substrate and the edge of each substrate shaping device.

10. 10. The substrate support mechanism of claim 9, wherein each seal is positioned so as not to contact the substrate when the substrate is provided on the support surface, and / or each seal includes a capillary stop when the substrate is provided on the support surface.

11. 7. A substrate support mechanism as described in any one of claims 1 to 6, wherein when a substrate is provided on the support surface, each substrate shaping device moves such that a vertical gap is formed between an upper surface of the substrate and a lower surface of each substrate shaping device.

12. 12. The substrate support mechanism of claim 11, further comprising a sensor system configured to measure the size of each vertical gap, and preferably further comprising a controller configured to control the movement of each substrate shaping device in response to the measured size of each vertical gap, and preferably wherein the controller is configured to control the movement of each substrate shaping device such that each vertical gap is 10 μm or less.

13. further comprising one or more further force-generating electrodes embedded within the substrate support and / or a surrounding structure of the substrate support; the one or more further force-generating electrodes are arranged such that when a substrate is provided on the support surface, each of the one or more further force-generating electrodes is positioned to apply an electrostatic force to the periphery of the substrate; 13. A substrate support mechanism as described in any one of claims 1 to 12, wherein each electrostatic force includes a component that is perpendicular to the plane of the support surface and that is directed to move the substrate towards the support surface, and wherein there are preferably a plurality of further force-generating electrodes embedded within the substrate support and / or a surrounding structure of the substrate support, and wherein, in a plan view, the plurality of further force-generating electrodes are arranged around the support surface.

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

15. 1. A method of changing the shape of a substrate, comprising: Loading a substrate onto the substrate support of a substrate support mechanism according to any one of claims 1 to 13; applying an electrostatic force to the outer periphery of the substrate; A method comprising:

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