Substrate table, lithographic apparatus, sticker, covering and method of operating a lithographic apparatus - Patents.com

Abstract

A substrate table for use in an immersion lithography apparatus having a support area defining a support surface for supporting a substrate to be patterned and a top surface surrounding the support area, the top surface comprising an outer region that is substantially planar and a transition region adjacent the support area, the transition region being not coplanar with the outer region to improve a level transition between the outer region and a non-standard substrate having a thickness that differs from the distance between the support surface and a nominal surface defined by the outer region.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to European Application No. 22154248.3, filed on January 31, 2022, which is incorporated by reference in its entirety into this specification.

[0002] The present invention relates to a substrate table, a lithographic apparatus incorporating a substrate table, a sticker for use with a substrate table, a covering for a substrate table and a method of operating a lithographic apparatus. [Background technology]

[0003]

[0003] A lithographic apparatus is a machine constructed 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 (often also referred to as a "design layout" or "design") from a patterning device (e.g. mask) onto a layer of radiation-sensitive material (resist) provided on the substrate (e.g. wafer).

[0004]

[0004] To project a pattern onto a substrate, lithographic apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be patterned 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 with a wavelength in the range of 4 nm 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.

[0005]

[0005] To enable improved resolution of smaller features, immersion technology has been introduced into lithography systems. In an immersion lithography apparatus, a layer of immersion liquid, having a relatively high refractive index, is placed in a space between the apparatus's projection system (through which the patterned beam is projected towards the substrate) and the substrate. The immersion liquid eventually covers the part of the substrate that is below the final element of the projection system. Thus, at least the part of the substrate where exposure takes place is immersed in liquid. The effect of the immersion liquid is that the exposure radiation has a shorter wavelength in the immersion liquid than in a gas, allowing imaging of smaller features. (It can also be thought that the effect of the liquid is to increase the effective numerical aperture (NA) of the system, and to increase the depth of focus.)

[0006]

[0006] In commercial immersion lithography, the immersion liquid is water. Typically, the water is highly pure distilled water, such as ultrapure water (UPW), commonly used in semiconductor manufacturing plants. In an immersion system, the UPW is often purified and may undergo additional processing steps before being delivered to the space as the immersion liquid. Besides water, other liquids with high refractive indexes can be used as the immersion liquid. Examples include hydrocarbons, such as fluorocarbons, and / or aqueous solutions. Additionally, other fluids besides liquids are also envisioned for use in immersion lithography.

[0007]

[0007] In the present description, reference is made to localized immersion, where the immersion liquid is confined in a space between a final element and a surface facing the final element during use. The facing surface is either the surface of the substrate or a surface of the support table (or substrate support) that is flush with the surface of the substrate. (Please note that in the following text, references to the surface of the substrate may also or instead refer to the surface of the substrate support and vice versa, unless otherwise stated.) The immersion is confined to a space using a fluid handling structure that is between the projection system and the stage. The space filled by the immersion liquid is smaller than the top surface of the substrate in plan, and this space is kept substantially stationary relative to the projection system while the substrate and substrate stage move underneath.

[0008]

[0008] A fluid handling structure is a structure that supplies immersion liquid to and removes immersion liquid from a space, thereby confining the immersion liquid to the space. It includes features that are part of a fluid supply system. Figures 2 and 3 show different supply devices that can be used in such a system. The arrangement disclosed in WO99 / 49504 is an early fluid handling structure that includes pipes that supply or remove immersion liquid from a space and move in response to relative movement of a stage below the projection system. In more recent designs, the fluid handling structure extends along at least part of the boundary of the space between the final element of the projection system and the support table or substrate, so as to partially define the space.

[0009]

[0009] A fluid handling structure may have a variety of selected functions. Each function is derived from corresponding features that enable the fluid handling structure to achieve that function. A fluid handling structure may be referred to by a number of different terms, each describing a function, for example a barrier member, a seal member, a fluid supply system, a fluid removal system, a liquid confinement structure, etc.

[0010]

[0010] The fluid handling structure as a barrier member is a barrier to the flow of immersion liquid from the space. The structure as a liquid confinement structure confines the immersion liquid to the space. The sealing feature of the fluid handling structure as a seal member forms a seal that confines the immersion liquid to the space. The sealing feature may include an additional gas flow from an opening in the surface of the seal member, such as a gas knife.

[0011]

[0011] During a series of exposures, the edge of the immersion liquid repeatedly crosses the edge of the substrate and these edge crossings are a significant cause of defects in manufactured devices due to disturbances of the immersion liquid meniscus. Summary of the Invention

[0012] It is desirable to reduce defects caused by edge crossings of the immersion liquid.

[0013]

[0013] According to one aspect of the present invention, there is provided a substrate table for use in an immersion lithography apparatus having a support area defining a support surface for supporting a substrate to be patterned and an upper surface surrounding the support area, the upper surface comprising an outer region which is substantially planar and a transition region adjacent to the support area, the transition region being not coplanar with the outer region thereby improving a level transition between the outer region and a non-standard substrate having a thickness which differs from the distance between the support surface and a nominal surface defined by the outer region.

[0014]

[0014] According to one aspect of the present invention, there is provided an immersion lithography apparatus comprising the above-mentioned substrate table, a liquid confinement system configured to confine immersion liquid in a space, and a positioning system configured to position the substrate table relative to the liquid confinement system.

[0015]

[0015] According to one aspect of the present invention, there is provided a sticker for use with a substrate table of an immersion lithography apparatus, the sticker having a shape and configuration for defining a transition region of an upper surface of the substrate table, the transition region being effective to reduce a level transition between an outer region of the upper surface of the substrate table and a substrate held by the substrate table, the substrate having a thickness greater than the height of the upper surface relative to a support surface for the substrate.

[0016]

[0016] According to one aspect of the present invention, there is provided a cover for use with a substrate table of an immersion lithography apparatus, the cover having a shape and configuration to define a transition region of an upper surface of the substrate table, the transition region being effective to reduce a level transition between an outer region of the upper surface of the substrate table and a substrate held by the substrate table, the substrate having a thickness that differs from the height of the upper surface relative to a support surface for the substrate.

[0017]

[0017] According to one aspect of the present invention, there is provided a method of operating an immersion lithography apparatus comprising providing immersion liquid to a top surface of a substrate table and controlling the immersion liquid to move from the top surface onto a substrate supported by a support area of ​​the substrate table, the immersion liquid moving across a transition region as it moves along the top surface towards the substrate, the transition region being effective to reduce a level transition between an outer region of the top surface of the substrate table and the substrate, the substrate having a thickness that differs from the height of the top surface relative to the support area. [Brief description of the drawings]

[0018]

[0018] Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which like reference symbols indicate corresponding parts, in which:

[0019] [Figure 1] 1 depicts a lithographic apparatus according to one embodiment of the present invention; [Diagram 2]

[0020] 1 depicts a liquid supply system for use in a lithographic projection apparatus. [Diagram 3]

[0021] 1 illustrates, in cross-section, a further liquid supply system to which the present invention can be applied; [Figure 4]

[0022] 1 depicts a part of a substrate table in a lithographic apparatus to which the present invention can be applied; [Diagram 5]

[0023] 1 depicts diagrammatically a portion of a conventional lithographic apparatus illustrating the problem addressed by the present invention; [Figure 6]

[0024] FIG. 6 is an enlarged view of a portion of FIG. [Figure 7]

[0025] 1 depicts a part of a lithographic apparatus in which the first solution is applied; [Figure 8]

[0026] 1 shows a part of a lithographic apparatus including a first practical embodiment of a first solution. [Figure 9]

[0027] 2 shows a part of a lithographic apparatus comprising a second practical embodiment of the first solution. [Figure 10]

[0028] 3 depicts a part of a lithographic apparatus in which the second solution is applied; [Figure 11]

[0029] 1 shows a part of a lithographic apparatus illustrating a third solution. [Figure 12]

[0030] 3 depicts a part of a lithographic apparatus including a first variant of the third solution; [Figure 13]

[0031] 4 depicts a part of a lithographic apparatus including a second variant of the third solution; [Figure 14]

[0032] 13 shows an alternative actuator configuration that can be used in a third solution. [Figure 15]

[0032] An alternative actuator configuration that can be used in the third solution is shown. [Figure 16]

[0032] An alternative actuator configuration that can be used in the third solution is shown. [Figure 17]

[0033] 4 illustrates the movement of a substrate relative to a liquid confinement system; [Figure 18A]

[0034] 4 shows a cross section of the covering according to the fourth solution in the lowered position. [Figure 18B]

[0034] A cross section of a covering according to the fourth solution in a raised position is shown. [Figure 19A]

[0035] 13 shows some coverings by variants of the fourth solution. [Figure 19B]

[0035] A part of the covering according to the fourth solution variant is shown. [Figure 19C]

[0035] A part of the covering according to the fourth solution variant is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020]

[0036] In this document, the terms "radiation" and "beam" are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (eg, having a wavelength of 365 nm, 248 nm, 193 nm, 157 nm or 126 nm).

[0021]

[0037] The terms "reticle," "mask," or "patterning device" as employed herein may be broadly interpreted to refer to any general purpose patterning device that can be used to impart a patterned cross-section to an incoming radiation beam, corresponding to the pattern to be created in a target portion of a substrate. The term "light valve" can also be used in this context. Besides the classic mask (transmissive or reflective; binary, phase-shifting, hybrid, etc.), examples of other such patterning devices include: - Programmable mirror arrays: Further information regarding such mirror arrays is given in US Patent Nos. 5,296,891 and 5,523,193, which are incorporated herein by reference. - A programmable LCD array. An example of such a construction is given in US Patent No. 5,229,872, which is incorporated herein by reference.

[0022]

[0038] Figure 1 diagrammatically depicts a lithographic apparatus comprising: - optionally an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or DUV radiation); a support structure (e.g. mask table) MT constructed to support a patterning device (e.g. mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA according to certain parameters; - a support table connected to a second positioner PW configured to accurately position the surface of the table, e.g. a substrate W, according to certain parameters, e.g. a sensor table supporting one or more sensors, or a support table WT constructed to hold a substrate (e.g. a resist-coated wafer) W a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to a radiation beam B by a patterning device MA onto a target portion C (e.g. comprising one or more dies) of a substrate W;

[0023]

[0039] Referring to Figure 1, in operation the illumination system IL receives a radiation beam or radiation from a radiation source SO, for example via a beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic and / or other types of optical components, or any combination thereof, to guide, shape and / or control the radiation. The illuminator IL may be used to condition a radiation beam B in a plane of the patterning device MA to have a desired spatial and angular intensity distribution in its cross-section.

[0024]

[0040] The term "projection system" as used herein should be broadly interpreted to encompass any type of projection system including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optical systems, or any combination thereof, appropriate for the exposure radiation being used and / or other factors such as the use of an immersion liquid. Any use of the term "projection lens" herein may be considered as synonymous with the more general term "projection system".

[0025]

[0041] The lithographic apparatus may be of a type having two or more support tables, e.g. two or more support tables, or a combination of one or more support tables with one or more cleaning tables, sensor tables, or measurement tables. For example, the lithographic apparatus may be a multi-stage apparatus comprising two or more tables positioned at an exposure side of a projection system, each comprising and / or holding one or more objects. In one example, one or more of the tables may hold a radiation sensitive substrate. In one example, one or more of the tables may hold a sensor to measure radiation from the projection system. In one example, the multi-stage apparatus comprises a first table (i.e. the support table) configured to hold a radiation sensitive substrate, and a second table (hereinafter generally, but without limitation, referred to as a measurement table, a sensor table, and / or a cleaning table) that is not configured to hold a radiation sensitive substrate. The second table may comprise and / or hold one or more objects other than a radiation sensitive substrate. Such one or more objects may include one or more selected from a sensor to measure radiation from the projection system, one or more alignment marks, and / or a cleaning device (e.g. for cleaning a liquid confinement structure).

[0026]

[0042] In operation, the radiation beam B is incident on the patterning device MA held on the support structure MT and is patterned by a pattern (design layout) present on the patterning device MA. Having traversed 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 a position sensor IF (e.g. an interferometric device, a linear encoder, a 2D encoder or a capacitive sensor), the support table W can be accurately moved, for example to position the various target portions C at focused and aligned positions in the path of the radiation beam B. Similarly, the patterning device MA can be accurately positioned with respect to the path of the radiation beam B using the first positioner PM and another position sensor (not explicitly shown in FIG. 1 ). The patterning device MA and substrate W can be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks M1, M2 as illustrated occupy dedicated target portions, they may be located in spaces between target portions C (these are known as scribe-lane alignment marks).

[0027]

[0043] Figure 2 illustrates diagrammatically a localized liquid supply system or fluid handling system. The liquid supply system is provided with a fluid handling structure IH (or liquid confinement structure) that extends along at least part of the boundary of the space 11 between the final element of the projection system PS and the support table WT or substrate W. The fluid handling structure IH is substantially stationary relative to the projection system PS in the XY plane, although there may be some relative movement in the Z direction (in the direction of the optical axis). In one example, a seal is formed between the fluid handling structure IH and the surface of the substrate W, which may be a contactless seal such as a gas seal (such a system with a gas seal is disclosed in EP 1 420 298) or a liquid seal.

[0028]

[0044] The fluid handling structure IH at least partly confines immersion liquid in a space 11 between the final element of the projection system PS and the substrate W. The space 11 is at least partly formed by the fluid handling structure IH positioned below and surrounding the final element of the projection system PS. Immersion liquid is introduced into the space 11 in the fluid handling structure IH below the projection system PS by one of the liquid openings 13. Immersion liquid can also be removed by another of the liquid openings 13. Immersion liquid may be introduced into the space 11 via at least two liquid openings 13. Which of the liquid openings 13 is used to supply immersion liquid and optionally which of the liquid openings 13 is used to remove immersion liquid may depend on the direction of movement of the support table WT.

[0029]

[0045] The immersion liquid can be contained in the space 11 by a contactless seal, such as a gas seal 16 formed by gas that, in use, forms between the bottom of the fluid handling structure IH and the surface of the substrate W. Gas in the gas seal 16 is provided under pressure through an inlet 15 to the gap between the fluid handling structure IH and the substrate W. Gas is extracted via an outlet 14. The overpressure at the gas inlet 15, the vacuum level at the outlet 14 and the geometry of the gap are configured to create a high velocity inward gas flow that confines the immersion liquid. Such a system is disclosed in US 2004 / 0207824, which is incorporated herein by reference in its entirety. In one example, the fluid handling structure IH does not have a gas seal 16.

[0030]

[0046] Figure 3 depicts a cross-sectional side view of a further liquid supply or fluid handling system according to an embodiment. The arrangement depicted in Figure 3 and described below may be applied to the lithographic apparatus described above and shown in Figure 1. The liquid supply system is provided with a fluid handling structure IH (or liquid confinement structure) that extends along at least part of the boundary of a space 11 between the final element of the projection system PS and the support table WT or substrate W.

[0031]

[0047] The fluid handling structure IH at least partly confines immersion liquid in a space 11 between the final element of the projection system PS and the substrate W. The space 11 is at least partly formed by the fluid handling structure IH positioned below and surrounding the final element of the projection system PS. In one example, the fluid handling structure IH comprises a body member 53 and a porous member 33. The porous member 33 is plate-like and has a number of holes (i.e. openings or pores). In one example, the porous member 33 is a mesh plate, with a multitude of small holes 84 formed in a mesh. Such a system is disclosed in US 2010 / 0045949 A1, which is incorporated herein by reference in its entirety.

[0032]

[0048] The body member 53 comprises a supply port 72 capable of supplying immersion liquid to the space 11 and a recovery port 73 capable of recovering immersion liquid from the space 11. The supply port 72 is connected to a liquid supply device 75 via a passage 74. The liquid supply device 75 is capable of supplying immersion liquid to the supply port 72 via the corresponding passage 74. The recovery port 73 is capable of recovering immersion liquid from the space 11. The recovery port 73 is connected to a liquid recovery device 80 via a passage 79. The liquid recovery device 80 recovers the immersion liquid recovered via the recovery port 73 through the passage 29. The porous member 33 is arranged at the recovery port 73. By performing a liquid supply operation using the supply port 72 and performing a liquid recovery operation using the porous member 33, a space 11 is formed between the projection system PS and the fluid handling structure IH on one side and the substrate W on the other side.

[0033]

[0049] Figure 4 shows part of a lithographic apparatus according to an embodiment of the invention. The arrangement shown in Figure 4 and described below can be applied to the above lithographic apparatus shown in Figure 1. Figure 4 shows a cross-section of a substrate WT and a substrate W. A gap 5 exists between the edge of the substrate W and the edge of the substrate table WT. At other times, such as when the edge of the substrate W is imaged or when the substrate W is initially moved under the projection system PS (as described above), the immersion space 11, filled with liquid by (for example) the liquid confinement structure IH, passes at least partially over the gap 5 between the edge of the substrate W and the edge of the substrate table WT. This can cause liquid from the immersion space 11 to seep into the gap 5.

[0034]

[0050] The substrate W is held by a support 30 (e.g. a pimple or burl table) which includes one or more protrusions 32 (i.e. burls). The support 30 is an example of an object holder. Another example of an object holder is a mask holder. Negative pressure applied between the substrate W and the substrate table WT ensures that the substrate W is held securely in position. However, if immersion liquid gets between the substrate W and the support 30 this can cause problems, especially when unloading the substrate W.

[0035]

[0051] To address immersion liquid entering the gap 5, at least one drain 10, 20 is provided at the edge of the substrate W to remove immersion liquid entering the gap 5. In the embodiment of Figure 4, two drains 10, 20 are shown, however there may be only one drain or more than two drains. In an embodiment, each of the drains 10, 20 is annular so as to surround the entire periphery of the substrate W.

[0036]

[0052] The main function of the first drain 10 (radially outboard of the edge of the substrate W / supports 30) is to help prevent gas bubbles from entering the immersion space 11 in which the liquid of the liquid confinement structure IH is present. Such bubbles could have detrimental effects on imaging of the substrate W. The first drain 10 is present to help avoid gas in the gap 5 escaping into the immersion space 11 in the liquid confinement structure IH. If gas escapes into the immersion space 11, this could cause bubbles to float in the immersion space 11. If such bubbles are in the path of the projection beam, they could cause imaging errors. 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 table WT in which the substrate W is located. The edge of the recess in the substrate table WT may be defined by a cover ring 130, optionally spaced from the supports 30 of the substrate table WT. The cover ring 130 may be ring-shaped in plan and surrounds the outer edge of the substrate W. What is extracted into the first drain 10 is mostly gas and only a small amount of immersion liquid.

[0037]

[0053] A second drain 20 (radially inward from the edge of the substrate W / support 30) is provided to help prevent liquid finding its way 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 20 reduces or eliminates any problems that may arise due to liquid finding its way underneath the substrate W.

[0038]

[0054] As shown in Figure 4, in an embodiment, the lithographic apparatus comprises a channel 46 for the two-phase flow to pass through. The channel 46 is formed in the block. The first and second drains 10, 20 are provided with openings 42, 22 and channels 46, 26, respectively. The channels 46, 26 are in fluid communication with the openings 42, 22 through passages 44, 24, respectively.

[0039]

[0055] As shown in figure 4, the cover ring 130 has an upper surface 60. The upper surface 60 extends circumferentially around the substrate W on the support 30. In use of the lithographic apparatus, the liquid confinement structure IH moves relative to the substrate table WT. During this relative movement, the liquid confinement structure IH moves across the gap 5 between the cover ring 130 and the substrate W. In an embodiment, the relative movement is caused by the substrate table WT moving below the liquid confinement structure IH. In an alternative embodiment, the relative movement is caused by the liquid confinement structure IH moving over the substrate table WT. In a further alternative embodiment, the relative movement is caused by both the substrate table WT moving below the liquid confinement structure IH and the liquid confinement structure IH moving over the substrate WT. In the following description, movement of the liquid confinement structure IH is used to mean relative movement of the liquid confinement structure IH with respect to the substrate table WT.

[0040]

[0056] Figure 5 shows a close-up of part of the lithographic apparatus, in particular the liquid confinement structure IH and the substrate table WT near the edge of the substrate W. As mentioned above, the cover ring 130 provides a top surface 60 that immediately surrounds the substrate W. Typically, this top surface 60 is flush with the substrate W if the substrate W is of standard thickness, for example 775 μm. Around the periphery of the cover ring 130 is a body, referred to herein as an encoder block 140, which supports various sensors and fiducials, such as a transmission image sensor (TIS) that are used to align the substrate table WT to the image projected by the projection system PS and to align the substrate W to the substrate table WT. The encoder block 140 forms a major part of the substrate table WT and may extend below the support 30 to support it. The encoder block 140 is made of Zerodur TMThe cover ring 130 is preferably made of a material with high rigidity and low coefficient of thermal expansion, such as Cordierite or Cordierite. A sticker 150 is provided to cover the gap between the encoder block 140 and the cover ring 130 and to prevent immersion liquid from entering the gap. The sticker 150 is called a film or foil and may be made of, for example, stainless steel, and is secured to the cover ring 130 and the encoder block 140 by a low-residue adhesive. The sticker 150 may be made of glass, metal, plastic, or other non-reactive material. The sticker 150 may be secured by adhesive, thin film liquid, or vacuum suction.

[0041]

[0057] When using an immersion lithography apparatus to pattern a substrate W having a thickness greater or less than the nominal thickness defined by the lithography apparatus, a height difference Δh occurs between the top of the substrate W and the top of the cover ring 130. The case of a thick wafer is shown in FIG. 6, which is a further enlargement of a portion of FIG. 5. It should be noted that this figure and the following figures are not to scale and certain vertical dimensions are exaggerated for clarity. One situation in which it is desirable to pattern a thick substrate is, for example, the manufacture of three-dimensional memory structures. In 3D-NAND, the structures built on the substrate may significantly increase the thickness of the substrate, for example, to 30 μm or more, which is beyond the normal tolerance range for substrate thickness. It may also be desirable to pattern a thinner substrate than standard, which may result in a height difference between the top of the substrate W and the top of the cover ring 130.

[0042]

[0058] The inventors have determined that the presence of a height difference (in either direction) between the top of the substrate W and the top of the cover ring 130 (or an equivalent surface adjacent the edge of the substrate W) can adversely affect the performance of the lithographic apparatus. For example, such a height difference can disrupt the meniscus of the immersion liquid as it moves across the edge of the substrate W in either direction. A disruption of the immersion liquid meniscus can cause air bubbles to form in the immersion liquid and / or droplets of liquid to break off from the immersion liquid and remain on the substrate W or cover ring 130. Both air bubbles and droplets are known causes of defects in immersion lithographic apparatus.

[0043]

[0059] It is proposed to provide a transition region 135 on the top surface of the substrate table WT close to the support area on which the substrate W is held, which transition region 135 is not (at least partially) flush with an outer region of the top surface of the substrate table WT to improve the level transition between the outer region and the non-standard substrate. The effect of the transition region 135 may be to make the level transition gradual rather than abrupt, to split the level transition into two or more small transitions, to move the transition further away from the edge of the substrate W, or a combination of two or more of these effects. A gradual level transition or two or more small transitions may be less likely to disturb the meniscus than a single large transition. Moving the transition away from the edge of the substrate W may mean that any disturbance of the meniscus is less likely to cause defects in the patterned substrate. It is preferable for the transition region to be close to the edge of the substrate, so that the meniscus of the immersion liquid is not disturbed by a gap. In particular, it is preferable for the innermost edge of the transition region to be no more than 3 mm, preferably no more than 1 mm, away from the outer edge of the support area.

[0044]

[0060] The height of the peak or depth of the valley of the transition region will depend on the expected thickness variation of the substrate. However, it is preferred that at least a portion of the transition region is more than 10 μm from the nominal surface, preferably more than 20 μm. It is preferred that no portion of the transition region is more than 300 μm from the nominal surface, preferably more than 150 μm, more preferably more than 50 μm.

[0045]

[0061] Thus, the transition region 135 may include a sloped or curved surface and / or one or more steps as a means to achieve an improved level transition.

[0046]

[0062] As shown in Figure 7, an example of a transition region 135 is a region of the upper surface adjacent to the edge of the support area for the substrate W, which is not flush with the outer region of the substrate table WT (here embodied by the upper surface of the encoder block 140), whereby the level difference Δh' between the upper surface of the substrate W and the highest point of the transition region 135 is smaller than the level difference Δh between the upper surface of the substrate W and a nominal plane defined by the outer region of the upper surface of the substrate table WT.

[0047]

[0063] The actual implementation of the transition region 135 can take a variety of approaches. The first approach is shown in FIG. 8, which shows a tapered ticker 151 extending from the inner periphery of the cover ring 130 to the encoder block 140, covering the gap between the cover ring 130 and the encoder block 140. The tapered ticker 151 can thus replace a sticker 150 of a conventional configuration. The tapered ticker 151 may be formed of a polymer and formed into a desired thickness profile using laser ablation. Other materials are possible, including stainless steel. Although the tapered ticker 151 is shown as having a linear change in thickness with distance from the inner edge, other profiles are possible, including a staircase-like profile with several shallow steps, and the like. Desirably, the tapered ticker 151 has a thickness that decreases monotonically outward from its inner edge.

[0048]

[0064] A second approach for practical implementation of the transition area 135 is shown in FIG. 9. In this configuration, the transition area 135 is defined by a multi-layer sticker 152 including multiple stickers with different shapes, e.g., a first sticker 152a and a second sticker 152b, stacked on top of each other. More than one sticker can be used. Similar to the configuration of FIG. 8, the multi-layer sticker 152 extends from the inner periphery of the cover ring 130 to the encoder block 140, covering the gap between the cover ring 130 and the encoder block 140. Thus, in the conventional configuration, the multi-layer sticker 152 can replace the sticker 150. FIG. 9 shows the stickers stacked in such a way that the size of the stickers increases toward the top (i.e., the smallest sticker is at the bottom). In this configuration, the larger sticker(s) smooths out the step(s) formed by the outer edge of the smaller sticker(s) below it. It is also possible to stack the stickers in such a way that the size of the stickers decreases toward the top. This implies a steeper step, but prevents the creation of voids that the immersion liquid could seep in. Yet another method is to stack stickers of decreasing size, with the largest one on top, smoothing out the step formed by the lower stickers.

[0049]

[0065] The multi-layer sticker 152 is advantageous in that it allows the use of sticker materials, such as stainless steel, for which it may be difficult to create stickers with a varying height profile. It may also be advantageous when the level difference to be improved is very large. Of course it is also possible to combine the concepts of the configurations of figures 8 and 9, i.e. to have a multi-layer sticker formed of stickers with a varying height profile. For example, the edges of the stickers that make up the multi-layer sticker may be chamfered, for example at 60°, to form a bevel.

[0050]

[0066] A solution using stickers has the advantage that no modification of the cover ring 130 or the encoder block 140 is required. Thus, a sticker-based solution can be a retrofit of existing equipment in the field. The height of the sticker can be chosen depending on the recipe of the device to be manufactured. If a lithographic apparatus is dedicated to patterning substrates of non-standard thickness for a sufficient period of time, it may be economical to install or replace stickers of an appropriate thickness. Using a low-residue adhesive to fix the stickers in place minimizes the downtime required to install or replace the stickers.

[0051]

[0067] The stickers used in the present invention preferably extend closer to the inner edge of the covering ring 130 than conventional stickers. Conventional stickers only cover the covering ring 130 enough to allow for proper adhesion. The stickers used in the present invention preferably extend to the inner edge of the covering ring 130. The stickers used in the present invention may extend such that their inner edge is no more than 3 mm away from the outer edge of the support area, preferably no more than 1 mm.

[0052]

[0068] FIG. 10 shows a part of a lithographic apparatus according to a second solution to the problem of excessive level transitions at the edge of the substrate W. As shown in FIG. 10, the cover ring 130 has a depth and / or position such that the level difference Δh between the outer regions (e.g. defined by the encoder block 140) of the top surface of the substrate table WT is divided into two or more smaller level differences Δh1 and Δh2. For example, a first level difference Δh1 is defined between the top surface of the substrate W and the top surface 60 of the cover ring 130, and a second level difference Δh2 is defined between the top surface 60 of the cover ring 130 and the top surface of the encoder block 140. The ratio of dividing the total level difference Δh between Δhl and Δh2 can be selected to suit the particular application. In general, it is desirable that Δhl and Δh2 are approximately the same or that Δhl is smaller than Δh2. The transition region 135 is formed by the fact that the top surface 60 of the cover ring 130 has a level intermediate the levels of the top surface of the substrate W and the top surface of the encoder block 140.

[0053]

[0069] The depth (thickness) of the covering ring 130 can be easily determined during manufacturing. Making a slightly thicker covering ring 130 is not as difficult as making a standard thickness covering ring. The vertical position of the covering ring 130 can be determined by a crowbar (not shown) on the support 30 or by providing a suitable spacer between the covering ring 130 and the support 30.

[0054]

[0070] In a variant of the second solution, the cover ring 130 is made in two parts separated by a horizontal plane. Either the upper or lower version can be made with different thicknesses and swapped to suit the thickness of the substrate W to be patterned. The two parts of the cover ring 130 may be held together, for example, by magnets or a mechanical interlock.

[0055]

[0071] In a second solution, a sticker 150 can still be used between the cover ring 130 and the encoder block 140 to prevent immersion liquid from entering the gap between the cover ring 130 and the encoder block 140. The sticker 150 may be a sticker according to the first solution to further improve the level transition between the encoder block 140 and the substrate W.

[0056]

[0072] Because the cover ring 130 is a more substantial component than the sticker, manufacturing a cover ring to fit substrates W of different thicknesses will be more expensive than manufacturing different stickers, but the cover ring is also a field replaceable component that does not require excessive downtime to replace. Thus, if the apparatus is to pattern substrates of non-standard thicknesses over an extended period of time, a suitable cover ring can be installed or replaced.

[0057]

[0073] The second solution is particularly useful in case of thinner than standard substrates W, since the covering ring 130 can be easily thinned. In this case, a thinner covering ring 130 can be combined with a sticker of variable thickness, the thickness of which increases depending on the distance from the inner periphery, in contrast to the sticker of the first solution.

[0058]

[0074] A third solution is shown in Fig. 11. According to the third solution, a covering ring 131 is provided with an actuator 133, which can change the shape of its upper surface 60 to form a transition region 135. A controller (not shown) controls the actuator 133. The covering ring 131 has a default configuration, shown in dashed lines in the figure, where the upper surface of the covering ring 131 is flush with the upper surface of the encoder block 140 and with a substrate of standard thickness. The actuator 133 selectively rotates the covering ring 131 about a pivot 132 to form a transition region 135 between the encoder block 140 and a substrate of non-standard thickness. Although the figure shows the covering ring 131 rotating to accommodate a thicker substrate W, the covering ring 131 could easily be rotated in the opposite direction to accommodate a thinner substrate W.

[0059]

[0075] Only a small tilt is required since the width of the actuated covering ring 131 is 10 mm or more and the level difference to be accommodated is likely to be less than 100 μm. It will be appreciated that since the covering ring 131 is annular, tilting the covering ring 131 will distort the covering ring 131 and cause its upper surface 60 to assume the shape of a partial conical surface. Because the required tilt is small, it is possible to distort the covering ring 131 even if it is made of a relatively hard material such as tungsten, stainless steel or SiSiC. The actuator 133 may be, for example, a piezoelectric device, a pneumatic device or a solenoid.

[0060]

[0076] In a third solution, a sticker 150 between the covering ring 131 and the encoder block 140 can still be used to prevent immersion liquid from entering the gap between the covering ring 131 and the encoder block 140. The standard sticker 150 is flexible enough to accommodate the movement of the actuated covering ring 131.

[0061]

[0077] The third solution has the advantage that the cover ring 131 can be switched to the desired configuration for the substrate to be patterned in a short time without opening the apparatus, and is therefore particularly applicable when patterning smaller batches of substrates of different thicknesses.

[0062]

[0078] Fig. 12 shows a first variant of the third solution. In this configuration, the cover ring 131 is provided with two actuators 133a and 133b spaced apart in the radial direction of the substrate W. A controller (not shown) controls the actuators 133a, 133b. The use of two spaced actuators 133a, 133b allows both the height and the angle of the transition region 135 to be controlled, providing more flexibility in accommodating substrates of different thicknesses. The lithographer can select the combination of level step(s) and sloped transition region 135 that best suits the recipe to be carried out.

[0063]

[0079] Figure 13 shows a second variant of the third solution. In this configuration, an actuated covering ring 131 is provided with a number of actuator units 133-1 to 133-3 spaced circumferentially around the ring. A controller (not shown) controls the actuator units 133-1 to 133-3. Each of the actuator units 133-1 to 133-3 may be a single actuator as shown in Figure 11 or a pair of actuators 133a, 133b as shown in Figure 12. The use of a number of actuator units 133 spaced around the covering ring 131 allows for local control of the profile of the transition region 135, so that, for example, most of the covering ring 131 is flat, but only where and when the liquid confinement structure IH intersects the covering ring 131, the covering ring 131 is moved or deformed to form the transition region 135. The local distortion of the covering ring 131 may reduce stress on the covering ring 131 and power consumption of the actuator units 133.

[0064]

[0080] FIG. 17 shows in plan view various positions of the liquid confinement structure IH relative to the substrate W and the gap 5 at different times. In particular, FIG. 17 is a schematic diagram of the moment when the liquid confinement structure IH crosses the gap 5 around the edge of the substrate W. FIG. 17 shows a crossing of the liquid confinement structure IH such that at some point during the crossing, the meniscus 17 at the trailing edge of the immersion space 11 is approximately parallel to the gap 5. The meniscus 17 may not be exactly parallel to the gap 5, in particular because the gap 5 itself extends substantially circumferentially around the substrate W. However, as shown in FIG. 17, the meniscus 17 is substantially parallel to the gap 5. These crossings are therefore sometimes referred to as parallel crossings between the liquid confinement structure IH and the gap 5. It is known that parallel crossings increase the likelihood of water droplets settling on the substrate W, and therefore the likelihood of defects occurring near the position of the parallel crossing.

[0065]

[0081] Thus, in a second variant of the third solution, the actuator units 133 may be located only in the vicinity of the parallel intersection and / or activated only when a parallel intersection occurs to form the transition region 135. Similarly, in the static solution above, the profile of the sticker 150 and / or the covering 131 may vary in the circumferential direction, thereby providing the transition region 135 only in areas where disturbances of the meniscus 17 are most likely to occur and / or lead to defects.

[0066]

[0082] FIG. 14 shows an alternative actuator configuration that can be used in any embodiment of the third solution. As shown in FIG. 14, the actuated covering ring 131 is divided into a first section 131a and a second section 131b by a slit 131c that extends into the covering ring 131 from its inner periphery. The actuator unit(s) 133 are disposed in the slit 131c to act between the first section 131a and the second section 131b. A controller (not shown) controls the actuator unit(s) 133. A flexible membrane 134 closes the slit 131c to prevent the ingress of immersion liquid. The second section 131b of the covering ring 131 is attached to the support 30 via a mount 136. This configuration allows the actuated covering ring 131 to be constructed as a drop-in replacement for conventional covering rings, without requiring mechanical modification of the support 30.

[0067]

[0083] FIG. 15 illustrates another alternative actuator configuration that can be used in any embodiment of the third solution. As shown in FIG. 15, the actuated cover ring 131 is divided into a first section 131a and a second section 131b by a slit 131c that extends into the cover ring 131 from its inner periphery. The second section 131b is itself divided into two elongated arms 131b1 and 131b2 that are joined at a joint 131b3. The actuator 133 is disposed between the elongated arms 131b1 and 131b2 and serves to separate them. A controller (not shown) controls the actuator 133. When the actuator 133 is actuated, the elongated arms 131b1 and 131b2 are forced apart, bending the joint 131b3, thereby rotating the first portion 131a to a desired angle. By making the elongated arms 131b1 and 131b2 longer and the joint 131b3 thinner, the desired tilt of the upper surface 60 of the actuated cover ring 131 can be achieved with a low force actuator.

[0068]

[0084] Figure 16 shows another alternative actuator configuration that can be used in any embodiment of the third solution. The actuator 133 can be a push-pull actuator (i.e. an actuator that applies a controllable force in both directions, rather than an actuator that applies a force in only one direction). The actuator 133 can be embedded in the support 30 and provided with a hinge to reduce normal forces. The actuator 133 can be configured to apply a linear force or a torque to the cover ring 131. The spacing between the pivot 132 and the actuator 131 can be selected depending on the force that can be applied by the actuator 133 and the torque required for the desired shape of the transition region 135.

[0069]

[0085] A fourth solution is shown in Figures 18a and b. In the fourth solution, the cover ring 130 is actuated to selectively raise and lower its upper surface depending on the thickness of the substrate to be patterned.

[0070]

[0086] As shown in Figures 18a and b, the cover ring 130 comprises a ring element 160 embedded in its upper surface 162. The ring element 160 is a deformable element comprising a piezoelectric, magnetostrictive or electrostrictive material. In a first mode, as shown in Figure 18a, the upper surface 161 of the ring element is placed flush with the upper surface 162 of the cover ring 130. In a second mode, the ring element 160 is "activated" (e.g. by applying a voltage, a magnetic field or an electric field), which causes the element upper surface 161 to be raised relative to the upper surface 162 (see Figure 18b) to form a transition region. Depending on the amount of activation, the height of the element 160 can be controlled to a desired level, for example to be flush with the top surface of the substrate W or to be at a level intermediate between the top surface of the substrate W and the top surface of the outer region of the substrate table WT. A controller (not shown) controls the activation of the ring element 160. The cover ring 130 may be provided with conductive leads to provide a voltage or current (locally) to the ring element 160 to initiate activation and control the amount of activation (height level of the upper surface 162).

[0071]

[0087] A deformable filling material can be provided to (partially) fill the gap between the ring element 160 and the covering ring 130. A foil, e.g. a sticker 150, can be provided on the top surface covering at least part of the top surface 161 of the ring element 160 and the top surface 162 of the covering ring 130, thereby covering the gap. It will be understood that the configuration of Figures 18a and 18B can be inverted such that the ring element 160 is at the bottom and pushes against the support, e.g. the support 30, on actuation, to raise the covering ring 130.

[0072]

[0088] A fourth solution variant is shown in Fig. 19a-c. According to this configuration, the cover ring 130 comprises a first (or lower) ring 171 and a second (or upper) ring 170. The second ring 170 is arranged to move coaxially with respect to the first ring 171. That is to say, the second ring 170 can be rotated about a common axis (not shown) by means of a sliding structure 172, for example one or more screws or cam surfaces. This rotational movement moves the second ring 170 upwards. This allows the level of the top surface 162 of the second ring 170 to be controlled to form a transition area. The top surface 162 can thus be controlled to a desired level, for example to be flush with the top surface of the substrate W or to be at an intermediate level between the top surface of the substrate W and the top surface of the outer area of ​​the substrate table WT.

[0073]

[0089] A controller (not shown) can be used to set the position of the second ring 170. The controller can, for example, control an electric motor (not shown) that initiates a rotational movement of the second ring 170 relative to the first ring 171, thereby raising the top surface 162. The device that rotates the second ring 170 can be an ultrasonic motor, a piezoelectric actuator, or a hydraulic actuator.

[0074]

[0090] It will be appreciated that the configuration of Figures 19a-c can be modified, for example by providing one or more channels on the upper surface of lower ring 171 provided with threads or cam surfaces, and corresponding protrusions (e.g. flanges or pins) on the lower surface of upper ring 170. A mechanism similar to the e-pin mechanism used to raise and lower the substrate W when loading and unloading the substrate W could also be used.

[0075]

[0091] It will be appreciated that the actuated solutions of the present invention, for example the third and fourth solutions above, can position the top surface of the transition region 135 continuously over a range of positions and / or inclinations or at a selected one of a set of pre-set positions and / or inclinations. The position and / or inclination of the transition region 135 may be pre-determined based on a recipe applied to a batch of substrates. The position and / or inclination of the transition region 135 may be determined for each substrate based on measurements made on a particular substrate, for example in a characterization process performed in the lithographic apparatus before exposure. For example, a level sensor (not shown) can be used to determine the level of the substrate W relative to an outer region of the top surface of the substrate table WT or the level of an edge region of the substrate W in order to set an appropriate position or inclination for the transition region 135.

[0076]

[0092] In the actuated solution of the present invention, the position or tilt for the transition region 135 may be set at an appropriate time before exposure begins and kept constant until exposure of one or more substrates is completed, or the actuation may be modified during the exposure process to, for example, set the transition region 135 only during partial or full crossing of the substrate edge.

[0077]

[0093] In the solution of the invention where the covering forms the transition region 135, whether by the special shape of the covering or by the actuation of the covering, it is desirable that the inner edge of the covering, or the part of the covering which forms the transition region 135, is no more than 3 mm, preferably no more than 1 mm, away from the outer edge of the support area.

[0078]

[0094] The present invention therefore allows the use of an immersion lithography apparatus to expose substrates with a wider range of thicknesses than was possible, whether the variations arise from differences in the base thickness of the substrate or the structures formed on the substrate. This can be achieved by exchanging field replaceable components between batches of substrates or by using actuated solutions. Existing immersion lithography apparatus can be retrofitted to expose substrates with a different nominal thickness than the substrate originally intended to be exposed. New immersion lithography apparatus can be built to expose substrates with non-standard thicknesses without the need to redesign other components of the substrate table WT (e.g., the encoder block 140) to place the entire top surface at a different level. For example, the encoder block 140 is a complex component with strict manufacturing specifications, so redesigning it would be a significant amount of work. It is also advantageous to be able to use the same encoder block 140 in immersion lithography apparatuses optimized for different substrate thicknesses.

[0079]

[0095] In some embodiments of the invention, the shape and configuration of a particular component is important. Accordingly, the invention may be embodied in a computer readable medium storing data defining both a digital representation of the component and operational instructions adapted to control a computer aided manufacturing machine, such as an additive manufacturing device or a subtractive manufacturing device such as a laser ablation device, to create a product using the digital representation of the product when the data is relayed to the computer aided manufacturing machine.

[0080]

[0096] As will be appreciated, any of the features described above may be used in conjunction with other features, and it is not just the combinations explicitly described that are encompassed by this application.

[0081]

[0097] Although specific reference is made in this specification to the use of lithographic apparatus in IC manufacture, it should be understood that the lithographic apparatus described herein may have other applications in the manufacture of components having micro-scale or even nano-scale features, such as 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.

[0082]

[0098] Exemplary embodiments of the invention are described in the following numbered clauses. 1. A substrate table for use in an immersion lithography apparatus having a support area defining a support surface for supporting a substrate to be patterned, and an upper surface surrounding the support area, the upper surface comprising an outer region that is substantially planar, and a transition region adjacent to the support area, the transition region not being coplanar with the outer region, thereby improving a level transition between the outer region and a non-standard substrate having a thickness different from the distance between the support surface and a nominal surface defined by the outer region. 2. A substrate table according to clause 1, wherein the transition region forms an annulus surrounding the support area. 3. A substrate table as described in clause 1, wherein the transition region extends along one or more distinct regions around the periphery of the support area. 4. A substrate table according to clause 1, 2 or 3, wherein the innermost edge of the transition region is no more than 3mm, preferably no more than 1mm, from the outer edge of the support area. 5. A substrate table according to any one of clauses 1 to 4, wherein at least part of the transition region is at a distance of more than 10 μm from the nominal surface, desirably more than 20 μm. 6. A substrate table according to any one of clauses 1 to 5, wherein no part of the transition region is more than 300 μm from the nominal surface, preferably more than 150 μm, more preferably more than 50 μm. 7. A substrate table according to any one of clauses 1 to 6, wherein the transition region comprises a slope region that is inclined relative to the nominal plane and adjacent the outer region. 8. A substrate table according to any one of clauses 1 to 7, wherein the transition region includes at least one step. 9. A substrate table according to any one of clauses 1 to 8, wherein the transition region projects upwardly from the outer region. 10. A substrate table according to any one of clauses 1 to 8, wherein the transition region extends downwardly from the outer region. 11. A substrate table according to any one of clauses 1 to 10, wherein the transition region comprises a sticker attached to a surface substantially coplanar with the outer region. 12. A substrate table as claimed in claim 11, wherein the transition region comprises a further sticker attached to the sticker. 13. A substrate table according to clause 11 or 12, wherein the substrate table comprises a body defining an outer region and a cover ring surrounding the support area, the sticker or further sticker filling a gap between the cover ring and the outer region. 14. A substrate table according to any one of clauses 11 to 13, wherein the sticker or further sticker is made from a polymer. 15. A substrate table according to any one of clauses 1 to 10, wherein the substrate table comprises a body defining an outer region and a cover ring surrounding the support area, the cover ring defining a transition region. 16. A substrate table as claimed in clause 15, wherein the cover ring comprises an upper ring portion and a lower ring portion, the upper ring portion defining a transition region and being separable from the lower ring portion. 17. A substrate table as claimed in clause 15, wherein the cover ring comprises a lower ring portion, an upper ring portion defining a transition region, and an actuator configured to alter the position of the upper ring portion relative to the nominal surface. 18. A substrate table according to clause 15, further comprising an actuator connected to the cover ring and configured to selectively alter a profile of the transition region. 19. A substrate table according to clause 18, wherein the actuator is configured to change the shape of the cover ring. 20. A substrate table according to clause 19, wherein the actuator is configured to change the shape of the entire cover ring. 21. A substrate table as described in clause 20, wherein the actuator is configured to change the shape of the cover ring between a first configuration in which the transition region conforms to a plane and a second configuration in which the transition region is a part conical surface. 22. A substrate table according to clause 19, wherein the actuator is configured to locally modify the shape of the cover ring. 23. A substrate table according to any one of clauses 18 to 22, wherein the actuator is configured to act between a cover ring and a body of the substrate table. 24. A substrate table according to any one of clauses 18 to 22, wherein the actuator is integrated in the cover ring and acts between two parts thereof. 25. A substrate table as claimed in clause 24, wherein the actuator is configured to rotate one part of the cover ring relative to the other part. 26. A substrate table according to any one of clauses 1 to 25; a liquid confinement system configured to confine immersion liquid to a space; a positioning system configured to position the substrate table relative to the liquid confinement system. 27. An immersion lithographic apparatus according to clause 26, when dependent on any one of clauses 18 to 25, further comprising a controller for controlling an actuator in relation to movement of the substrate table by the positioning system. 28. A sticker for use with a substrate table of an immersion lithography apparatus, the sticker having a shape and configuration for defining a transition region of an upper surface of the substrate table, the transition region being effective to reduce a level transition between an outer region of the upper surface of the substrate table and a substrate held by the substrate table, the substrate having a thickness greater than a height of the upper surface relative to a support surface for the substrate. 29. A cover ring for use with a substrate table of an immersion lithography apparatus, the cover ring having a shape and configuration to define a transition region of an upper surface of the substrate table, the transition region being effective to reduce a level transition between an outer region of the upper surface of the substrate table and a substrate held by the substrate table, the substrate having a thickness that differs from the height of the upper surface relative to a support surface for the substrate. 30. The cover ring of clause 29, wherein the cover ring comprises an upper ring portion and a lower ring portion, the upper ring portion defining a transition region and being separable from the lower ring portion. 31. The covering of clause 29, wherein the covering comprises a lower ring portion, an upper ring portion defining a transition region, and an actuator configured to change the position of the upper ring portion relative to the nominal surface. 32. The covering of clause 31, wherein the actuator is configured to change the shape of the covering between a first configuration in which the transition region conforms to a plane and a second configuration in which the transition region is a partial conical surface. 33. A covering according to clause 31, wherein the actuator is configured to locally change the shape of the covering. 34. The covering of clause 31, wherein the actuator is configured to rotate one portion of the covering relative to the other portion. 35. A computer readable medium storing data defining both a digital representation of a product as described in clause 28 or 29 and operating instructions adapted to control a computer aided manufacturing machine, such as an additive manufacturing device or a subtractive manufacturing device such as a laser ablation device, to produce a product using the digital representation of the product when the data is relayed to the computer aided manufacturing machine. 36. A method of operating an immersion lithography apparatus, the method comprising: providing immersion liquid to a top surface of the substrate table; controlling the immersion liquid to move from the top surface onto a substrate supported on a support area of ​​the substrate table; A method in which the immersion liquid moves across a transition region as it moves along the top surface towards the substrate, the transition region being effective to reduce a level transition between outer regions of the top surface of the substrate table and the substrate, the substrate having a thickness that differs from the height of the top surface relative to the support area.

[0083]

[0099] While specific embodiments of the present invention have been described above, it will be apparent that the present invention can 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 appended claims.

Claims

1. 1. A substrate table for use in an immersion lithographic apparatus having a support area defining a support surface for supporting a substrate to be patterned, and a top surface surrounding said support area, the upper surface comprises a substantially planar outer region and a transition region adjacent the support area; A substrate table, wherein the transition region is not coplanar with the outer region, thereby improving a level transition between the outer region and a non-standard substrate having a thickness different from the distance between the support surface and a nominal surface defined by the outer region.

2. The substrate table of claim 1 , wherein the transition region forms an annulus surrounding the support area or extends along one or more discrete regions around the periphery of the support area.

3. A substrate table according to claim 1 or 2, wherein an innermost edge of the transition region is no more than 3 mm, preferably no more than 1 mm, from an outer edge of the support area.

4. 4. A substrate table according to any one of claims 1 to 3, wherein at least part of the transition region is more than 10 μm from the nominal surface, preferably more than 20 μm, and / or no part of the transition region is more than 300 μm from the nominal surface, preferably not more than 150 μm, even more preferably not more than 50 μm, and / or the transition region comprises a sloped region that is inclined relative to the nominal surface and adjacent to the outer region, and / or the transition region comprises at least one step, and / or the transition region projects upwardly from the outer region, or the transition region extends downwardly from the outer region, and / or the transition region comprises a sticker adhered to a surface substantially coplanar with the outer region.

5. The substrate table of claim 4 , wherein the transition region comprises a further sticker attached to the sticker.

6. the substrate table comprising a body defining the outer region and a covering surrounding the support area; the sticker or the further sticker fills a gap between the covering and the outer area; and / or A substrate table according to claim 4 or 5, wherein the sticker or the further sticker is made from a polymer.

7. the substrate table comprising a body defining the outer region and a covering surrounding the support area; A substrate table according to any preceding claim, wherein the cover ring defines the transition region.

8. the cover ring comprises an upper ring portion and a lower ring portion; the upper ring portion defines the transition region and is separable from the lower ring portion; or 8. The substrate table of claim 7, wherein the cover ring comprises a lower ring portion and an upper ring portion defining the transition region and an actuator configured to vary a position of the upper ring portion relative to the nominal surface, or further comprises an actuator connected to the cover ring and configured to selectively vary a profile of the transition region.

9. the actuator is configured to change the shape of the cover ring; and / or A substrate table according to claim 8, wherein the actuator is configured to alter the overall shape of the cover ring or to locally alter the shape of the cover ring.

10. 10. The substrate table of claim 9, wherein the actuator is configured to change a shape of the cover ring between a first configuration in which the transition region conforms to a plane and a second configuration in which the transition region is a part conical surface.

11. the actuator is arranged to act between the cover ring and the body of the substrate table; or A substrate table according to any one of claims 8 to 10, wherein the actuator is integrated into the cover ring and acts between two parts thereof.

12. The substrate table of claim 11 , wherein the actuator is configured to rotate one part of the cover ring relative to another part.

13. A substrate table according to any one of claims 1 to 12; a liquid confinement system configured to confine immersion liquid to a space; a positioning system configured to position the substrate table relative to the liquid confinement system; and An immersion lithography apparatus comprising:

14. 1. A sticker for use with a substrate table of an immersion lithographic apparatus, comprising: the sticker has a shape and configuration to define a transition area of ​​a top surface of the substrate table; the transition region is effective to reduce a level transition between an outer region of the top surface of the substrate table and a substrate held by the substrate table; The substrate has a thickness greater than a height of the top surface relative to a support surface for the substrate.

15. 1. A cover ring for use with a substrate table of an immersion lithographic apparatus, comprising: the cover ring has a shape and configuration to define a transition region of a top surface of the substrate table; the transition region is effective to reduce a level transition between an outer region of the top surface of the substrate table and a substrate held by the substrate table; The substrate has a thickness that differs from the height of the top surface relative to a support surface for the substrate.

Images