BASE SUPPORT, BASE SUPPORT SYSTEM, AND METHODS OF CLAMPING THE BASE ON THE BASE SUPPORT

Abstract

The base support is configured to support the provided base. The base support consists of a main support body with a support surface and a flexible support element. The flexible support element includes a first surface to support the base and a second surface to be supported on the support surface of the main support body. The base support also includes a first clamping device to clamp the flexible support element onto the base and a second clamping device to clamp the flexible support element onto the main support body. The flexible support element has a flexibility that allows it to adapt its shape to an irregularly shaped base by the clamping force of the first clamping device when clamping the flexible support element onto the base.

Description

SUBSTRATE SUPPORT, SUBSTRATE SUPPORT SYSTEM AND METHOD TO CLAMP ASUBSTRATE ON A SUBSTRATE SUPPORTCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of EP application 23208330.3 which was filed on 7 November 2023 and of EP application 23216417.8 which was filed on 13 December 2023 and which are incorporated herein in their entirety by reference.FIELD

[0002] The present invention relates to a substrate support configured to support a substrate, a substrate support system comprising the substrate support, and a method to clamp a substrate on a substrate support.BACKGROUND

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern (also often referred to as “design layout” or “design”) of a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate (e.g., a wafer).

[0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements have continually been reduced while the amount of functional elements, such as transistors, per device has been steadily increasing over decades, following a trend commonly referred to as “Moore’s law”. To keep up with Moore’s law the semiconductor industry is chasing technologies that enable to create increasingly smaller features. To project a pattern on a substrate a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features which are patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm and 13.5 nm.

[0005] A lithographic apparatus may include an illumination system for providing a projection beam of radiation, and a support structure for supporting a patterning device. The patterning device may serve to impart the projection beam with a pattern in its cross-section. The apparatus may also include a projection system for projecting the patterned beam onto a target portion of a substrate.

[0006] In a lithographic apparatus, the substrate to be exposed (which may be referred to as a production substrate) may be held on a substrate support (sometimes referred to as a substrate table). The substrate support may be supported on a stage. In practice, substrates may be or become warped, for example due to a number of consecutive processing steps. The warped substrate may have different types of non-planar shapes, such as bowl-shaped, umbrella-shaped, saddle-shaped, (spatially) higher frequent shapes, etc. The non-planar shapes of a warped substrate may cause difficulties to clamp asubstrate on the substrate support. For example, warped substrates can result in a great amount of flow and pressure being required to clamp the substrate on the substrate support. This may possibly lead to high stress and damage of the substrate.

[0007] US 2022 / 197155 discloses a substrate support of which its shape can be actively controlled by a set of piezo actuators. The substrate support further comprises a sensor to determine the shape of the warped substrate. The set of piezo actuators is arranged to adapt the shape of the substrate support on the basis of this measured shape of the warped substrate. In the adapted shape of the substrate support, the substrate can be relatively easily be clamped on the substrate support using a clamping device. Thereafter, the substrate support and the substrate clamped thereon may be brought back to a substantially unactuated / straight position.

[0008] JP2000Z 124299 A discloses the use of a warpage sensor to detect the amount of warpage of a substrate. Based on the detected amount of warpage, the support surface of a substate support can be actively adapted to the measured shape of the substate.

[0009] US 2020 / 326635 discloses a substrate support having a substrate holder comprising a main body, first burls to support the substrate and second burls to be arranged on a support below the substrate support. In relaxed state distal end surfaces of a first subset of the first burls have a different height than distal end surfaces of a second subset of the first burls. The substrate holder may have a variable stiffness between positions of each of the first subset and the second subset of first burls to allow local deformation. The substrate holder of US 2020 / 326635 is not arranged to adapt its overall shape to the shape of a warped substrate.SUMMARY

[0010] An object of the present invention is to provide a substrate support configured to support a substrate. A further object of the invention is to provide a substrate support that is arranged to effectively clamp warped substrates. Another further object of the invention is to provide a substrate support system and a method to effectively clamp warped substrates on a substrate support.

[0011] According to an aspect of the invention there is provided a substrate support configured to support a substrate, comprising: a flexible support element, comprising a first side to support the substrate; and a first clamping device to clamp the flexible support element on the substrate; wherein the flexible support element has a flexibility that allows the flexible support element to adapt its shape to the substrate having a non-planar shape by a clamping force of the first clamping device when clamping the flexible support element on the substrate with the first clamping device.

[0012] In an embodiment, the substrate support comprises a main support body to support the flexible support element.

[0013] In an embodiment, the main support body has a support surface and wherein the flexible support element comprises a second side to be supported on the support surface of the main supportbody, wherein the substrate support comprises a second clamping device to clamp the flexible support element on the main support body.

[0014] According to an aspect of the invention, there is provided a substrate support system comprising such substrate support.

[0015] According to an aspect of the invention there is provided a method to clamp a substrate on such substrate support, the method comprising the steps of: clamping with the first clamping device the substrate on the flexible support element, while allowing the flexible support element to adapt its shape to the substrate having a non-planar shape by a clamping force of the first clamping device; and while the substrate is clamped on the flexible support element, clamping with the second clamping device the flexible support element and the substrate clamped thereon on the main support body.

[0016] In an embodiment, the substrate support according to the invention is a substrate support of a substrate processing device, such as a lithographic apparatus or a substrate measuring apparatus.

[0017] In another embodiment, the substrate support according to the invention is a substrate storage station or a substrate handler, for example a substrate storage station or a substrate handler having a temperature conditioning device.

[0018] Further embodiments, features and advantages of the present invention, as well as the structure and operation of the various embodiments features and advantages of the present invention, as well as the structure and operation of the various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments of the invention will now be described by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:Figure 1 schematically depicts an overview of a lithographic apparatus;Figure 2 depicts a plan view of a substrate support;Figure 3 depicts a cross-sectional view of the substrate support of Figure 2;Figure 4 depicts a first embodiment of a substrate support having a flexible support element;Figures 5A-5D show subsequent steps of loading a warped substrate on the substrate support of Figure 4;Figures 6A-6C depict a second embodiment of a substrate support having a flexible support element;Figure 7 shows a detail of an embodiment of a flexible support element;Figure 8 shows a view on the first side of an alternative embodiment of the flexible support element; andFigure 9 shows a view on the second side of the flexible support element of Figure 8.Figures 10A and 10B depict a first further embodiment of a substrate support having a flexible support element; andFigures 11A and 11B depict a second further embodiment of a substrate support having a flexible support element.

[0020] The features shown in the figures are not necessarily to scale, and the size and / or arrangement depicted is not limiting. It will be understood that the figures include optional features which may not be essential to the invention. Furthermore, not all of the features of the substrate support are depicted in each of the figures, and the figures may only show some of the components relevant for describing a particular feature.DETAILED DESCRIPTION

[0021] In the present document, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., with a wavelength of 436, 405, 365, 248, 193, 157, 126 or 13.5 nm).

[0022] The term “reticle”, “mask” or “patterning device” as employed in this text may be broadly interpreted as referring to a generic patterning device that can be used to endow an incoming radiation beam with a patterned cross-section, corresponding to a pattern that is to be created in a target portion of the 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 a programmable mirror array and a programmable LCD array.

[0023] Figure 1 schematically depicts a lithographic apparatus LA. The lithographic apparatus LA includes an illumination system (also referred to as illuminator) IL configured to condition a radiation beam B (e.g., EUV radiation or DUV radiation), a mask support (e.g., a mask table) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA in accordance with certain parameters, a substrate support (e.g., a substrate table or a support table) WT constructed to hold a substrate (e.g., a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate support WT in accordance with certain parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.

[0024] In operation, the illumination system IL receives the radiation beam B from a radiation source SO, e.g., via a beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for directing, shaping, and / or controlling radiation. The illuminator IL may be used to condition the radiation beam B to have a desired spatial and angular intensity distribution in its cross section at a plane of the patterning device MA.

[0025] The term “projection system” PS used herein should be broadly interpreted as encompassing various types of projection system, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, and / or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system” PS.

[0026] The lithographic apparatus LA may be of a type wherein at least a portion of the substrate W may be covered by an immersion liquid having a relatively high refractive index, e.g., water, so as to fill an immersion space between the projection system PS and the substrate W - which is also referred to as immersion lithography. More information on immersion techniques is given in US 6,952,253, which is incorporated herein by reference.

[0027] The lithographic apparatus may be of a type having two or more substrate supports WT (also named “dual stage”). In such “multiple stage” machine, the substrate supports WT may be used in parallel, and / or steps in preparation of a subsequent exposure of the substrate W may be carried out on the substrate W located on one of the substrate support WT while another substrate W on the other substrate support WT is being used for exposing a pattern on the other substrate W.

[0028] In addition to the substrate support WT, the lithographic apparatus LA may comprise a measurement stage (not depicted in Figure 1). 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 a part of the projection system PS or a part of a system that provides the immersion liquid. The measurement stage may move beneath the projection system PS when the substrate support WT is away from the projection system PS.

[0029] In operation, the radiation beam B is incident on the patterning device, e.g., mask, MA which is held on the mask support MT, and is patterned by the pattern (design layout) present on patterning device MA. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and a position measurement system PMS, the substrate support WT can be moved accurately, e.g., so as to position different target portions C in the path of the radiation beam B at a focused and aligned position. Similarly, the first positioner PM and possibly another position sensor (which is not explicitly depicted in Figure 1) may be used to accurately position the patterning device MA with respect to the path of the radiation beam B. Patterning device MA and substrate W may be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2. Although the substrate alignment marks Pl, P2 as illustrated occupy dedicated target portions, they may be located in spaces between target portions. Substrate alignment marks Pl, P2 are known as scribe-lane alignment marks when these are located between the target portions C.

[0030] In this specification, a Cartesian coordinate system is used. The Cartesian coordinate system has three axis, i.e., an x-axis, a y-axis and a z-axis. Each of the three axes is orthogonal to the other two axes. A rotation around the x-axis is referred to as an Rx-rotation. A rotation around the y-axis is referred to as an Ry-rotation. A rotation around about the z-axis is referred to as an Rz-rotation. The x-axis and the y-axis define a horizontal plane, whereas the z-axis is in a vertical direction. The Cartesian coordinate system is not limiting the invention and is used for clarification only. Instead, another coordinate system, such as a cylindrical coordinate system, may be used to clarify the invention. The orientation of the Cartesian coordinate system may be different, for example, such that the z-axis has a component along the horizontal plane.

[0031] In a lithographic apparatus LA it is necessary to position with great accuracy the upper surface of a substrate W to be exposed in the plane of best focus of the aerial image of the pattern projected by the projection system PS. To achieve this, the substrate W can be held on a substrate support WT. The surface of the substrate support WT that supports the substrate W can be provided with a plurality of burls (protrusions or support elements) whose distal ends can be coplanar in a nominal support plane. The burls, though numerous, may be small in cross-sectional area parallel to the support plane so that the total cross-sectional area of their distal ends is a few percent, e.g., less than 5%, of the surface area of the substrate W. The gas pressure in the space between the substrate support WT and the substrate W may be reduced relative to the pressure above the substrate W to create a force clamping the substrate W to the substrate support WT.

[0032] A plan view of a substrate support 1 is shown in Figure 2. A partial cross section of the substrate support 1 is depicted in Figure 3. The substrate support 1 may comprise a main body 10 having an upper surface 11. The main body 10 may form a substantial portion of the substrate support 1. The upper surface 11 may be a top surface of the main body 10 when positioned as shown in Figure 3. That is, the upper surface 11 may be top surface in the Z-direction (the vertical direction).

[0033] The substrate support 1 may comprise a plurality of burls (protrusions or support members) 20 connected to, and protruding from, the upper surface 11 of the main body 10. Optionally, the substrate support 1 may comprise a plurality of burls (protrusions or support members) 20 connected to, and protruding from, the lower surface (opposite the upper surface 11) of the main body 10. The plurality of burls 20 may have proximal ends 21, which are situated near the main body 10 when in position, and distal ends 22. The distal ends 22 may be at opposite ends of the plurality of burls 20 to the proximal ends 21. That is, the distal ends 22 may be situated at an end of the burl 20 away from the main body 10.

[0034] The plurality of burls 20 may have a central longitudinal axis 23, with the proximal end 21 at one end of the burl 20 and the distal end 22 at the other end of the burl 20 along the central longitudinal axis 23. Thus, each of the plurality of burls 20 may have a central longitudinal axis 23 from the proximal end 21 to the distal end 22.

[0035] The distal ends 22 of the plurality of burls 20 form or define a support plane for a substrate W. Specifically, the distal ends 22 of the plurality of burls 20 may support a lower surface 31 of the substrate W. An upper surface 32 of the substrate W may be a surface opposite the lower surface 31. The upper surface 32 may be a surface which is configured to receive the radiation beam B.

[0036] The support plane may be formed in a substantially flat plane. Consequently, the substrate W can be positioned on the support plane to also be substantially flat, which can reduce errors in the pattern printed onto the substrate W (i.e., defectivity).

[0037] As shown in Figure 3, the plurality of burls 20 may be substantially frusto-conical, i.e. a truncated cone, or may be conical in shape. They may instead be substantially cylindrical. A frustoconical burl 20 may be stronger than a cylindrical burl 20 and thus have less likelihood of breaking. Preferably the plurality of burls 20 have the same shape as each other.

[0038] The plurality of burls 20 may be connected to the upper surface 11 of the main body 10 in any suitable way. The plurality of burls 20 may be separate components which are attached to the upper surface 11 of the main body 10. Alternatively, the plurality of burls 20 may be integral to the main body 10. In other words, the plurality of burls 20 may be formed as protrusions from the upper surface 11 of the main body 10, i.e. the plurality of burls 20 may be formed as a single part with the main body 10.

[0039] The substrate support 1 may be configured to enable fluid to be extracted from between the substrate W supported on the support plane and the upper surface 11. Fluid at the edge of the substrate W may be drawn under the substrate W. As fluid is extracted the pressure beneath the substrate W is reduced relative to pressure above the substrate W, and the edge of the substrate W will lower towards the substrate support 1. The substrate W can be clamped by extracting fluid in the space below the substrate W to provide a reduced relative pressure in the space between the substrate support 1 and the substrate W.

[0040] The main body 10 may comprise at least one extraction opening 12 through which the fluid is extracted. There may be a plurality of extraction openings 12.

[0041] It is beneficial to reduce leakage of fluid into the space between the substrate W and the main body 10 when the substrate W is clamped. Therefore, it may be beneficial to provide a physical boundary positioned near the edge of the substrate support 1. The physical boundary could be formed towards an edge of the main body 10 as shown in Figures 2 and 3. The physical boundary could be formed by a sealing member 40. The sealing member 40 may be a wall type protrusion formed around the edge of the main body 10, for example, around the circumference of the main body 10. The sealing member 40 may be formed to provide a seal between the lower side, e.g., lower surface 31, of the substrate W and the substrate support 1 around the edge of the substrate W. The seal provided by the sealing member 40 need not be a perfect seal but may be a partial seal that reduces but does not eliminate flow of fluid into the space between the substrate support 1 and substrate W.

[0042] The sealing member 40 may surround the plurality of burls 20. The sealing member 40 may protrude from the upper surface 11 of the main body 10. The sealing member 40 may be connected to the main body 10 in any way. The sealing member 40 may be integral with the main body 10.

[0043] A pressure sensor (not depicted in the drawings) may be used to measure the pressure between the substrate W and the upper surface 11 of the main body 10. Various sensors for measuring the pressure in the space below the substrate W are known. For example, a pressure sensor as disclosed in WO 2017 / 137129 Al, which is hereby incorporated by reference in its entirety, provides an example of an appropriate pressure sensor which might be used.

[0044] A flow rate sensor (not depicted in drawings) may be used to measure the flow rate of the fluid extracted via the extraction opening 12. Various sensors for measuring the flow rate from the space below the substrate W are known.

[0045] For the present invention, the exact arrangement of the substrate support 1 is not particularly limited. For example, the exact arrangement of burls 20, sealing member 40 and extraction openings 12 in the substrate support 1 is not particularly limited.

[0046] In practice, substrates W may be or become warped, for example due to a number of consecutive processing steps. The warped substrate W may have different types of non-planar shapes, such as bowl-shaped, umbrella-shaped, saddle-shaped, or (spatially) higher frequent shapes, etc. The non-planar shapes of a warped substrate W may cause difficulties to clamp a substrate W on the substrate support 1.

[0047] For example, when a bowl-shaped substrate W is placed on the substrate support 1 shown in Figures 2 and 3, the substrate W may only be supported at its central area on the substrate support 1. At the edge of the support surface, there may be a substantial spacing between the sealing edge 40 of the substrate support 1 and the substrate W. When a vacuum clamping force is exerted on the substrate W, by extracting fluid through the at least one extraction opening 12, the spacing between the sealing member 40 of the substrate support 1 and the substrate W may result in a great amount of flow and pressure being required to clamp the substrate W on the substrate support 1. This may possibly lead to high stress and damage of the substrate W.

[0048] Figure 4 shows an embodiment of a substrate support 50 configured to support a substrate W. The substrate support 50 is in particular arranged to clamp a warped substrate W on the substrate support 50.

[0049] The substrate support 50 comprises a main support body 51 and a flexible support element 52. The main support body 51 is a rigid element, for example a mirror block, an encoder block, or a separate support element placed on or in a mirror block or an encoder block. The main support 50 may be thermally conditioned. The main support body 51 has a support surface 53. The flexible support element 52 is a flexible element comprising a first side to support the substrate W and a second side to be supported on the support surface 53 of the main support body 51. The flexibility of the flexiblesupport element 52 may be at least as large as the flexibility of the substrate W. Advantageously, the flexibility of the flexible support element 52 is larger than the flexibility of the substrate W.

[0050] The first side of the flexible support element 52 is provided with first burls (protrusions or support members) 54 similar to the embodiment shown in Figure 3. The first burls 54 are arranged to contact the substrate W which is supported by the flexible substrate element 52. Correspondingly, the second side of the flexible support element 52 is provided with second burls (protrusions or support members) 55 to support the flexible support element 52 on the support surface 53 of the main support body 51.

[0051] A first clamping device 58 is provided to clamp the flexible support element 52 on the substrate W. The first clamping device 58 uses a first clamping space 56 provided between the flexible support element 52 and the substrate W. The clamping space 56 is formed between the first burls 54 arranged at the first side of the flexible support element 52. At its circumference the first clamping space 56 is delimited by a first sealing member 57. By creating a pressure in the first clamping space 56 which is lower than the pressure above the substrate W, the first clamping device 58 may clamp the substrate W on the flexible support element 52 of the substrate support 50. The first clamping space 56 thus forms a first clamping pad to exert a clamping force between the substrate W and the flexible support element 52.

[0052] To create a relatively low pressure in the first clamping space 56, the first clamping device 58 may provide a first pump device to pump fluid, e.g., air, away from the first clamping space 56 through an extraction opening 91 in the flexible support element 52 and a first extraction channel 59 in the main support body 51 aligned with the extraction opening 91. Such clamping device that is based on a relative negative pressure with respect to the environment may also be referred to a as vacuum clamping device. The force with which the clamping device attracts the substrate may be referred to as vacuum clamping force.

[0053] A second clamping device 62 is provided to clamp the flexible support element 52 on the main support body 51. The second clamping device 62 uses a second clamping space 60 formed between the second burls 55 provided on the second side of the flexible support element 52. The second clamping space 60 is circumferentially delimited by a second sealing member 61. By creating a pressure in the second clamping space 60 which is lower than the pressure in the environment of the substrate support50, the second clamping device 62 may clamp the flexible support element 52 on the main support body51. The second clamping space 60 thus forms a second clamping pad to exert a clamping force between the main support body 51 and the flexible support element 52.

[0054] To create a relatively low pressure in the second clamping space 60, the second clamping device 62 may provide a second pump device to pump fluid, e.g., air, away from the second clamping space 60 through a second extraction channel 63 in the main support body 51. The second clamping device 62 which creates a clamping force based on a relative negative pressure with respect to the environment may also be referred to as second vacuum clamping device.

[0055] In the main support body 51 a plurality of e-pins 64 are arranged. The e-pins 64 are movable between a retracted position, in which the e-pins 64 are mainly retracted in the main support body 51 and an extended position in which the e-pins 64 extend above the upper ends of the first burls 54. The e-pins 64 are used to lift the substrate W, after a lithographic process has been carried out, from the first burls 54 by moving the e-pins 64 from the retracted position to the extended position. In the extended position in which the substrate W is spaced from the first burls 54, a substrate handling device (not shown), for example a substrate handling robot, may take over the substrate W from the substrate support 50. Correspondingly, the e-pins 64 may be used to receive, while in the extended position, a substrate W from a substrate handling device and to subsequently position the substrate W on the first burls 54 by retracting the e-pins 64 from the extended position to the retracted position. The flexible support element 52 comprises openings through which the e-pins 64 may extend in order to directly support the substrate W.

[0056] In the first clamping space 56 a plurality of e-pin sealing members 65 are arranged to reduce leakage between the respective e-pin constructions and the first clamping space 56. Correspondingly, there is provided an extraction opening sealing member 66 in the second clamping space 60 at the location of the extraction opening to reduce leakage between the first extraction channel 59 and the second clamping space 60. Further sealing members may be provided at other suitable locations to prevent or reduces leakage from the first clamping space 56 and / or the second clamping space 60.

[0057] The substrate support 50 may be part of a substrate support system further comprising a controller 100 to control the first clamping device 58 and the second clamping device 62. The controller 100 may for example be arranged to control the first pump device to activate, when desired, the first clamping device 58, and to control the second pump device to activate, when desired, the second clamping device 62.

[0058] In Figure 4, a straight non-warped substrate W is supported on the substrate support 50. Such straight non-warped substrate W may be clamped on the substrate support 50 using the first clamping device 58 to clamp the flexible support element 52 on the substrate W and the second clamping device 62 to clamp the flexible support element 52 on the main support body 51.

[0059] The substrate support 50 shown in Figure 4 is arranged to facilitate the clamping of a warped substrate W on the substrate support 50.

[0060] Figures 5A-5D show subsequent steps in the clamping of a warped substrate W on the substrate support 50. The warped substrate W shown in Figures 5A-5D is bowl-shaped. The substrate support 50 may however also be used to clamp other types of warped substrates, such as umbrellashaped, saddle-shaped, taco-shaped substrates, (spatially) higher frequent shapes or substrates having another non-planar shape.

[0061] Figure 5A shows the substrate support 50 with a plurality of e-pins 64 placed in the extended position. A substrate W is arranged on the tops of the e-pins 64. The advantage of this extended position is that the lower side of the substrate W is accessible for the substrate handling robot (not shown). Inalternative embodiments, it may not be required that e-pins 64 or other lifting elements are provided in order to load the substrate W on the substrate support 50, for example when the substrate W can be held at its upper side. In such embodiments, the e-pins 64 may be omitted. Once the substrate W is loaded on the e-pins 64, the e-pins 64 may be moved from the extended position shown in Figure 5A to the retracted position.

[0062] Figure 5B shows the e-pins 64 in retracted position. In this retracted position the e-pins 64 no longer support the substrate W. Instead the substrate W is supported on the distal ends of the first burls 54 of the flexible support element 52. As the substrate W is bowl-shaped, the substrate W is only supported by a part of the first burls 54, in particular the first burls 54 arranged in a center part of the flexible support element 52. At the outer circumference of the substrate W, the substrate W is, due to its bowl-shape, spaced from the first sealing member 57.

[0063] To facilitate clamping of the substrate W on the substrate support 50, the flexible support element 52 has a flexibility that allows the flexible support element 52 to adapt its shape to the warped substrate W when clamping the flexible support element 52 on the substrate W with the first clamping device 58. Due to the flexibility of the flexible support element 52 which may be at least as large as the flexibility of the substrate W, the flexible support element 52 will deform when the first clamping device 58 is activated to clamp the flexible support element 52 on the substrate W. As a result of this clamping the flexible support element 52 will automatically adapt its shape to the non-planar shape of the warped substrate W.

[0064] In this application automatically adapt its shape to the non-planar shape of the warped substrate W means that the adaptation of the shape of the flexible support element 52 to the shape of the substate W is not based on knowledge of the shape of the substrate W. Such knowledge may for example comprise measured data obtained by a warpage sensor that is used to actively adapt the shape of a substrate support as proposed in US 2022 / 197155 and JP2000 / 124299A. In contrast, the flexibility of the flexible support element 52 allows to adapt its shape to the substrate W based on the clamping force provided by the first clamping device 58 without the need to provide knowledge, for example measurement data with respect to the shape of the substrate W. It is noted that in this clamping process of the flexible support element 52 on the substrate W, the shape of the substrate W may also change due to the clamping force of the first clamping device 52.

[0065] To clamp the flexible support element 52 on the substrate W, the controller 100 may activate the first clamping device 58 to create a clamping force between the flexible support element 52 and the substrate W. Although there is still a gap between the first sealing member 57 and the substrate W, the flexibility of the flexible support element 52 substantially reduces the flow and pressure required to clamp the flexible support element 52 on the substrate W. To allow the deformation of the flexible support element 52 the second clamping device 62 is not yet activated.

[0066] Figure 5C shows the state in which the first clamping device 58 is activated, as indicated by an arrow aligned with the first extraction channel 59 showing the flow of air created by the first pumpdevice. The flexible support element 52 has been deformed to a state in which the shape of the flexible support element 52 is adapted to the shape of the warped substrate W such that the flexible support element 52 is clamped on the substrate 52 over substantially the complete surface area of the first clamping space 56.

[0067] As a subsequent step of clamping the substrate W on the substrate support 50, the controller 100 may activate the second clamping device 62 such that a clamping force is created between the flexible support element 52 and the main support body 51. The first clamping device 58 will remain activated such that the flexible support element 52 is clamped on the substrate W. The flows of air created by the first pump device and the second pump device to create a low pressure in the first clamping space 56 and the second clamping space 60, respectively, are indicated by two arrows in Figure 5C aligned with the first extraction channel 59 and the second extraction channel 63, respectively.

[0068] Since the main support body 51 is a rigid body compared to the flexible support element 52, the clamping force of the second clamping device 62 will pull the flexible support element 52 and the substrate W on the support surface 53 therewith straightening the flexible support element 52 and the substrate W supported thereon. As a result, the warped substrate W will be deformed from the bowlshape to a flat planar shape. In this flat planar state, the substate W is ready for further processing of the substrate W in a substrate processing apparatus, such as a lithographic apparatus LA or a metrology apparatus.

[0069] Figure 5D shows the state in which the first clamping device 58 and the second clamping device 62 are activated such that the flexible support element 52 is clamped on the main support body in a straight shape and the substrate is clamped in a flat planar state on the substrate support 50.

[0070] Figures 6A-6C show a second embodiment of a substrate support 50. The same parts or parts having a corresponding function are indicated by the same reference numerals. The main difference between the first embodiment of Figure 4 and the second embodiment of Figures 6A-6C is that instead of an annual sealing ring 61 on the second side of the flexible support element 52, an annular extendible seal 70 is provided between the main support body 51 and the flexible support element 52. One end of the extendible seal 70 is connected to the main support body 51 and an opposed end of the extendible seal 70 is connected to the flexible support element 52. The main support body 51 comprises an annular recess 71 to accommodate at least partially the extendible seal 70 in particular in a non-extended state, as shown in Figures 6 A and 6C.

[0071] The extendible seal 70 may be a bellows type sealing skirt that completely seals the gap between the main support body 51 and the flexible support element 52. As a result, there is no air leakage through this gap when a fluid, e.g., air, is pumped through the second extraction channel 63 by the second pump device.

[0072] Figure 6A shows, corresponding to Figure 5B, a warped bowl-shaped substrate W supported by the first burls 54 on a center part of the substrate support 50. To clamp the substrate W on thesubstrate support 50 two subsequent steps are carried out. In a first step, the flexible support element 52 is clamped on the substrate W by activating the first clamping device 58, i.e. by creating a relatively low pressure in the first clamping space 56. The flexible support element 52 will due to its flexibility automatically adapt its shape to the shape of the warped substrate W while the flexible support element 52 is clamped on the substrate W.

[0073] Figure 6B shows, corresponding to Figure 5C, the flexible support element 52 clamped on the substrate W. Since the flexible support element 52 is deformed from a flat shape to a bowl-shape the distance between the main support body 51 and the flexible support element 52 at the circumferential edge of the flexible support element 52 is substantially increased.

[0074] To accommodate this spacing difference between the main support body 51 and the flexible support element 52, the extendible seal 70 is extended such that the second clamping space 60 remains a closed space, at least at the circumferential edge of the flexible support element 52. As the extendible seal 70 still closes the gap at the circumferential edge of the flexible support element 52, the flow and pressure needed to create a suitable clamping force with the second clamping device 62 may be substantially lower than the flow and pressure required in the first embodiment of Figure 4. Therefore, the presence of the extendible seal 70 facilitates the clamping of the flexible support element 52 with the substrate W clamped thereon on the support surface 53 of the substrate support 50.

[0075] Similar extendible seals 70 may also be provided as an alternative for other sealing members arranged in the second clamping space 60. For example, the extraction opening sealing member 66 in the second clamping space 60 may be replaced by an extendible seal, similar to the extendible seal 70, connected with one end to the main support body 51 and the other opposed end to the flexible support element 52. Also, extendible seals 70 may be arranged between the flexible support element 52 and the main support body to provide a closed fluid communication between an extraction opening in the flexible support element 52 and the first extraction channel.

[0076] The extendible seal 70 may be made of any suitable material. The material should be substantially air-tight and the extendible seal 70 has to withstand the pressure difference between the pressure in the second clamping space 60 and the pressure in the environment of the substrate support 50. The extendible seal 70 shown in Figures 6A-6C has a bellows configuration. In other embodiments, the extendible seal 70 may have other configurations such as telescopic elements, elastically deformable elements, or other suitable configurations to close a gap between the between the main support body 51 and the flexible support element 52. These alternative embodiment, may or may not be at least partly arranged in a recess to accommodate the extendible seal.

[0077] Figure 6C shows, corresponding to Figure 5D, the flexible support element 52 and substrate W clamped in a planar configuration on the main support body 51. As the gap between the flexible support element 52 and the main support body 51 is much smaller, the extendible seal 70 is folded and accommodated in the recess 71.

[0078] Figure 7 shows a detail of an embodiment of a flexible support element 52. The flexible support element 52 comprises two main functions. The flexible support element 52 has to be flexible in order to allow the flexible support element 52 to adapt its shape to the shape of a warped substrate W when clamping the flexible support element 52 on the substrate W with the first clamping device 58. At the same time the flexible support element 52 should provide a proper support for the substrate W on the support surface 53 of the rigid main support body 52. This support is provided by the first burls 54, the second burls 55 and the connection between the first burls 55 and the second burls 55 in the flexible support element 52.

[0079] In the embodiment of Figure 7, the flexible support element 52 comprises a plurality of burl elements 80 connected to each other by a body 81. Each burl element 80 comprises a first burl 54 extending at the first side of the flexible support element 52 and a second burl 55 extending at the second side of the flexible support element 52. Each first burl 54 and second burl 55 of a burl element 80 are rigidly connected to each other. This may be a direction connection between the first burl 54 and the second burl 55 or the burl element 80 may comprise a connection element to provide this connection. The burl elements 80 shown in Figure 7 are made of a first material and connected to each other with the body 81 which is made from a second material. The second material is more flexible than the first material.

[0080] The first material may be a relatively rigid material such that the burl elements 80 are rigid elements that provide proper support for supporting the substrate W. Each combination of the first burl 54 and the second burl 55 of a burl element 80 forms a supporting pillar to support the substrate W via the flexible support element 52 on the main support body 51. The second material may be a flexible material such the flexible support element 52 is relatively easy deformable to allow the flexible support element 52 to adapt its shape to the shape of a warped substrate W.

[0081] In an alternative embodiment, the material between the burl elements 80 may be relatively thin to provide flexibility to the flexible support element 52.

[0082] In an embodiment, the flexible support element 52 may be made from a silicon substrate or a similar device. On a first side of the substrate W the first burls 55 and sealing members, such as sealing member 57 and e-pin sealing member 65, may be etched or machined, while at the second side second burls 55 and respective sealing members, such as the second sealing member 61 or extraction opening sealing member 66, may be etched or machined. The resulting flexible support element has a center plane that may be relatively thin to provide sufficient flexibility to the flexible support element 52. In such embodiment, the whole flexible support element 52 may be made from substantially the same material.

[0083] Figure 8 shows a view on the first side of an alternative embodiment of the flexible support element 52. The flexible support element 52 comprises three e-pin openings 90 to allow e-pins 64 to pass through the flexible support element 52. Each of the e-pin openings 90 is surrounded by an e-pin sealing member 65. The flexible support element 52 comprises on the first side three concentric firstclamping spaces 56a, 56b, 56c. These first clamping spaces 56a, 56b, 56c comprise an inner first clamping space 56a, a middle first clamping space 56b and an outer first clamping space 56c. The inner first clamping space 56a is delimited by an inner first sealing member 57a. The middle first clamping space 56b is delimited by the inner first sealing member 57a and a middle first sealing member 57b. The outer first clamping space 56c is delimited by the middle first sealing member 57b and an outer first sealing member 57c. The outer first sealing member 57c corresponds to the first sealing member 57 of the embodiment of Figure 4 that delimits a single first clamping space 56 that extends over substantially the whole surface of the flexible support element 52.

[0084] The flexible support element 52 further comprises a first extraction opening 91a arranged in the inner first clamping space 56a, a second extraction opening 91b arranged in the middle first clamping space 56b and a third extraction opening 91c arranged in the outer first clamping space 56c. Each of the first extraction opening 91a, the second extraction opening 91b and the third extraction opening 91c may be arranged in fluid communication with a respective first extraction channel to extract fluid, e.g., air, from the inner first clamping space 56a, the middle first clamping space 56b and the outer first clamping space 56c, respectively, to create a clamping force between the flexible support element 52 and the substrate W in the respective area. This configuration of the three first clamping spaces 56a, 56b, 56c creates three concentric first clamping zones that can be used to clamp the flexible support element 52 on the substrate W.

[0085] The controller 100 may be configured to individually activate each of the first clamping zones, separately or in combination. The three concentric first clamping zones provide more flexibility to clamp the flexible support element 52 on the substrate W. For example, in a first step first a center part of the flexible support element 52 may be clamped on the substrate W using the inner first clamping space 56a. Subsequently, the flexible support element 52 may be clamped on the substrate W with the middle first clamping space 56b and thereafter with the outer first clamping space 56c. Any other order to clamp the flexible support element 52 on the substrate W may also be used. This clamping order may for example depend on the shape of the substrate W to be clamped.

[0086] Figure 9 shows a view on the second side of the flexible support element 52 of Figure 8. It can be seen that each of the first extraction opening 91a, the second extraction opening 91b and the third extraction opening 91c is surrounded by an extraction opening sealing member 66.

[0087] The flexible support element 52 comprises at the second side three concentric second clamping spaces 60a, 60b, 60c. These second clamping spaces 60a, 60b, 60c comprise an inner second clamping space 60a, a middle second clamping space 60b and an outer second clamping space 60c. The inner second clamping space 60a is delimited by an inner second sealing member 61a. The middle second clamping space 60b is delimited by the inner second sealing member 61a and a middle second sealing member 61b. The outer second clamping space 60c is delimited by the middle second sealing member 61b and an outer second sealing member 61c. The outer second sealing member 61c corresponds to the second sealing member 61 of the embodiment of Figure 4 that delimits a singlesecond clamping space 60 that extends over substantially the whole surface of the flexible support element 52.

[0088] Each of the inner second clamping space 60a, the middle second clamping space 60b and the outer second clamping space 60c may be arranged in fluid communication with a respective second extraction channel to extract fluid, e.g., air, from the inner second clamping space 60a, the middle second clamping space 60b and the outer second clamping space 60c, respectively. This configuration of the three second clamping spaces 60a, 60b, 60c creates three concentric second clamping zones that can be used to clamp the flexible support element 52 on the main support body 51.

[0089] The controller 100 may be configured to individually activate each of the second clamping zones, separately or in combination. This makes it possible to clamp the flexible support element 52 in any suitable order of the three second clamping zones on the main support body 51.

[0090] The configuration of three first clamping zones at the first side of the flexible support element 52 and three second clamping zones at the second side of the flexible support element 52 is just an example to subdivide the surface area of the first side and the second side of the flexible support element 52 into multiple clamping zones. Any other desired configuration with multiple clamping zones may also be used.

[0091] For example, the first clamping zones and / or second clamping zones may be distributed over the circumference of the surface area of the flexible support element 52. Such configuration may for instance comprise one central clamping zone and at least one ring of two, three, four or more clamping zones surrounding the central clamping zone. The number of clamping zones at the first side of the flexible support element 52 and the second side of the flexible support element 52 does not have to be the same, and the clamping zones at the first side of the flexible support element 52 and the second side of the flexible support element 52 do not have the same configuration. It is also possible to provide one clamping zone at one of the first and second side of the flexible support element 52, while two or more clamping zones are arranged at the other side of the flexible support element 52.

[0092] Figures 4-9 disclose embodiments of substrate supports 50 arranged to bring a warped substrate W to a flat planar state. In a first step the flexible support element 52 may be clamped on the substrate W using a first clamping device 58 while allowing the flexible support element 52 to adapt its shape to a non-planar shape of the warped substrate W. Subsequently, the flexible support element 52 and the substrate W clamped thereon are clamped on the main support body 51 by the second clamping device 62. This results in straightening of the warped substrate W.

[0093] In alternative embodiments of a substrate support, the substrate support may be arranged to hold the substrate W without the need of bringing the substrate W in a flat state. Such substrate support is for example a substrate storage station, or a substrate handler. At the same time it may be desirable that there is a close contact between the substrate W and the substrate support. For example, for temperature conditioning of a substrate W a close contact between the substrate support and the substrate W may be desirable to create an efficient heat transfer between the substrate support and thesubstrate W. In known embodiments of a substrate support, such as a substrate storage station, or a substrate handler this close contact may be challenging when the substrate W is warped.

[0094] Figures 10A and 10B show an embodiment of a substrate support 200 configured to support a substrate W. The substrate support 200 is in particular arranged to support a warped substrate W for temperature conditioning without the need to bring the substrate W in a flat state.

[0095] The substrate support 200 comprises a flexible support element 202 and optionally a main support body 201. The main support body 201 may be a rigid element. The main support body 201 may form a part of the substrate support 200. The main support body 201 has support elements 203 to support the flexible support element 202. The flexible support element 202 is a flexible element comprising a first side to support the substrate W. The support elements 203 may contact the second side of the flexible support element 202 to support the flexible support element 202. In alternative embodiments, the flexible support element 202 may be supported by any other suitable support, such as a support frame (not shown) or support elements 203 directly arranged on another structure (not shown). The main support body 201 does not have to be of a certain size or shape. Also, it is not required that the main support body 201 comprises a flat upper surface.

[0096] The flexibility of the flexible support element 202 may be at least as large as the flexibility of the substrate W. Advantageously, the flexibility of the flexible support element 202 is larger than the flexibility of the substrate W.

[0097] The first side of the flexible support element 202 may be provided with first burls 204 (protrusions or support members). The first burls 204 are arranged to contact the substrate W which is supported by the flexible substrate element 202. The first burls 204 may be made of any suitable material to support the substrate W may be optional. In an alternative embodiment, the flexible support element 202 may have an alternative support structure to support the substrate W, such as elongated structures that may be straight or curved, or by air bearing / Bernoulli pads, or any other suitable support structure.

[0098] A first clamping device 208 is provided to clamp the flexible support element 202 on the substrate W. The first clamping device 208 uses a first clamping space 206 provided between the flexible support element 202 and the substrate W. The clamping space 206 is formed between the first burls 204 arranged at the first side of the flexible support element 202. At its circumference the first clamping space 206 may optionally be delimited by a first sealing member 207. By creating a pressure in the first clamping space 206 which is lower than the pressure above the substrate W, the first clamping device 208 may clamp the substrate W on the flexible support element 202 of the substrate support 200. The first clamping space 206 thus forms a first clamping pad to exert a clamping force between the substrate W and the flexible support element 202. In alternative embodiments the first clamping device 208 may also be based on another clamping principle such as an electrostatic clamping device or a combination thereof.

[0099] To create a relatively low pressure in the first clamping space 206, the first clamping device 208 may provide a first pump device to pump fluid, e.g., air, away from the first clamping space 206 through an extraction opening 211 in the flexible support element 202 and a first extraction channel 209 connected to the extraction opening 211. Such clamping device that is based on a relative negative pressure with respect to the environment may also be referred to as a vacuum clamping device. The force with which the clamping device attracts the substrate W may be referred to as vacuum clamping force.

[0100] By proper selection of the height of the first burls 204 and vacuum supply location(s), the vacuum force of the first clamping device 208 may create a local bending moment that causes the flexible support element 202 to roll off onto the substrate W so they clamp together. This rolling off may facilitate the clamping of the flexible support element 202 on a substrate W, in particular in case of substrate W having large warpage, e.g., more than about 0.5 mm warpage.

[0101] The substrate support 200 shown in Figures 10A and 10B further comprises a temperature conditioning device having a temperature conditioning conduit 212 for guiding a conditioning fluid along the second side of the flexible support element 202. By guiding a conditioning fluid, for example water or another liquid with a desired temperature through the temperature conditioning conduit 212, the temperature of the flexible support element 202 and / or the substrate W can be actively controlled. The temperature conditioning device may comprise a pump (not shown) to pump the conditioning fluid through the temperature conditioning conduit 212 and a heating and / or cooling device (not shown) to heat / cool the conditioning fluid to the desired conditioning temperature. The pump and the heating and / or cooling device may be integrated in the substrate support 200 or be arranged at a separate location. A supply conduit and a return conduit (not shown) may connect the temperature conditioning conduit 212 to the pump and the heating and / or cooling device to form a circulation circuit for the conditioning fluid.

[0102] The temperature conditioning conduit 212 is arranged to cover a large surface area of the second side of the flexible support element 202, for example substantially the whole surface area of the second side of the flexible support element 202. The temperature conditioning conduit 212 may extend along a spiral shaped path.

[0103] The temperature conditioning conduit 212 has a stiffness that is relatively low compared to the stiffness of the flexible support element 202. This low stiffness may for example be obtained by using a material with a high elasticity and / or a low height. The temperature conditioning conduit 212 may for example be made of a polymer / elastomer material. In an embodiment, the temperature conditioning conduit 212 may be made of polyurethane and have a height of 1 mm to 10 mm.

[0104] Instead of being arranged in a spiral shaped path, the temperature conditioning conduit 212 may also be arranged in any other suitable configuration, for example Figures. 4 and 5 of US 2006 / 087637, Figures. 3 and 4 of US2008 / 158526 and Figures. 4 and 5 of US2007 / 263201, all of which are incorporated herein by reference. The temperature conditioning conduit 212 may follow one singlepath or have two or more parallel conduit paths. The temperature conditioning conduit 212 may also be shaped as an element that comprises a conditioning fluid space which is not tube shaped, for example a single conditioning fluid space covering the whole surface area of the flexible support element 202, or four conditioning fluid spaces each covering a quarter of the surface area of the flexible support element 202.

[0105] The temperature conditioning conduit 212 or temperature conditioning fluid space may be formed within a flexible sheet connected to the flexible support element 202, e.g., the temperature conditioning conduit 212 may be formed in a sheet of material that, as a whole, may be connected, for example glued to the flexible support element 202. In another embodiment, the temperature conditioning conduit 212 or temperature conditioning space may be an integrated part of the flexible support element 202, e.g., formed within the flexible support element 202.

[0106] The substrate support 200 may comprise e-pins (not shown) to lift the substrate W from the flexible support element 202. In this lifted position a substrate W may be taken from the substrate support 200 and / or be placed on the substrate support 200. Any other method for loading and unloading a substrate W on / from the substrate support 200 may also be used.

[0107] The substrate support 200 may be part of a substrate support system further comprising a controller 300 to control the first clamping device 208. The controller 300 may for example be arranged to control the first pump device to activate, when desired, the first clamping device 208.

[0108] In Figure 10A, a warped substrate W is supported on the distal ends of the first burls 204 of the flexible support element 202. As the substrate W is bowl-shaped, the substrate W is only supported by a part of the first burls 204, in particular the first burls 204 arranged in a center part of the flexible support element 202. At the outer circumference of the substrate W, the substrate W is, due to its bowlshape, spaced from the first sealing member 207. In such position, the temperature conditioning of the substrate W is more difficult as there is only contact between the center part of the substrate W and the flexible support element 202.

[0109] To improve the temperature conditioning of the substrate W without it being required to straighten the substrate W, the flexible support element 202 may be clamped on the substrate W with the first clamping device 208. Due to the flexibility of the flexible support element 202 which may be at least as large as the flexibility of the substrate W, the flexible support element 202 may deform when the first clamping device 208 is activated to clamp the flexible support element 202 on the substrate W. As a result of this clamping the flexible support element 202 may automatically adapt its shape to the non-planar shape of the warped substrate W.

[0110] Figure 10B shows the state in which the first clamping device 208 is activated by the controller 300. The flexible support element 202 has been deformed to a state in which the shape of the flexible support element 202 is adapted to the shape of the warped substrate W such that the flexible support element 202 is in contact with the substrate W over substantially the complete surface area of the first clamping space 206. The physical and / or thermal contact between the flexible support element 202 andthe substrate W is therefore improved significantly. As a result, the heat transfer between the flexible support element 202 and the substrate W will also be improved. This facilitates the temperature conditioning of the substrate W.

[0111] In order to allow the flexible support element 202 to adapt its shape to the shape of the substrate W, the flexible support element 202 may be formed as a thin plate. A thin plate also has a relatively low thermal mass, i.e. has a low heat capacity. At the same time the thickness of the flexible support element 202 may be selected to allow in-plane heat conduction in order to prevent thermal nonuniformities over the surface area of the flexible support element 202.

[0112] The flexible support element 202 can advantageously be made of a material with high thermal conductivity and a low Young’s modulus, for instance a thin plate of copper or aluminium. In an embodiment, the flexible support element 202 comprises a sheet of nickel-plated copper having a thickness between 0.2 mm and 0.5 mm.

[0113] A flat flexible support element 202, i.e. being flat in a relaxed state, is beneficial to suit all types of warped shapes, such as bowl-shaped, umbrella-shaped, saddle-shaped, (spatially) higher frequent shapes, etc. In an alternative embodiment a non-flat shape of the flexible support element 202 could be more suitable for a specific substrate shape, as the flexible support element 202 may more easily adapt to the specific substrate shape.

[0114] In the embodiment of Figures 10A and 10B, strain sensors 220 are provided at the second side of the flexible support element 202 that can be used to determine the shape of the flexible support element 202. When the flexible support element 202 is clamped on the substrate W by the first clamping device 208, the shape of the substrate W may be determined based on the measured shape of the flexible support element 202.

[0115] The determined shape of the substrate W may be used in further handling of the substrate W. For example, from the measurement signal over time just after clamping, residual vibrations can be measured. On the basis of this measurement the global stiffness of the substrate W may be determined. This is beneficial for clamping optimization in relation to the applied flow by the first pump device or metrology / exposure, e.g., edge, corrections when the substrate W is loaded on a substrate support for measurement and exposure step.

[0116] Instead of strain sensors 220 also any other type of sensor arranged at any suitable location may be used to measure the shape of the flexible support element 202, in particular when clamped on a substrate W.

[0117] Figures 11A and 11B show an alternative embodiment of a substrate support 200 for supporting a substrate W during temperature conditioning. The main difference between the substrate support 200 of Figures 10A and 10B and the substrate support 200 of Figures 11A and 11B is the configuration of the temperature conditioning device.

[0118] In the embodiment of Figures 11 A and 1 IB, the temperature conditioning device comprises a conditioning fluid space 221 formed between the main support body 201 and the flexible supportelement 202. The circumferential edge is closed by an annular extendible seal 222 between the main support body 201 and the flexible support element 202. One end of the extendible seal 222 is connected to the main support body 201 and an opposed end of the extendible seal 222 is connected to the flexible support element 202.

[0119] The extendible seal 222 may be a bellows type sealing skirt that completely seals the gap between the main support body 201 and the flexible support element 202. As a result, conditioning fluid, for example water, can be held within the conditioning fluid space 221.

[0120] A supply conduit 223 and a return conduit 224 may be connected to the conditioning fluid space 221 and a pump 225 to circulate the conditioning fluid. The temperature conditioning device may further comprise a heating and / or cooling device 226 to heat / cool the conditioning fluid to a desired conditioning temperature.

[0121] Figure 11A shows, a warped bowl-shaped substrate W supported by the first burls 204 on a center part of the substrate support 200. The flexible support element 202 can be clamped on the substrate W by exerting a clamping force with the first clamping device 208 while allowing the flexible support element 202 to adapt its shape to the non-planar shape of the substrate W.

[0122] Figure 1 IB shows the flexible support element 202 clamped on the substrate W. Since the flexible support element 202 is deformed from a flat shape to a bowl-shape the distance between the main support body 201 and the flexible support element 202 at the circumferential edge of the flexible support element 202 is substantially increased.

[0123] To accommodate this spacing difference between the main support body 201 and the flexible support element 202, the extendible seal 222 is extended such that the conditioning fluid space 221 remains a closed space, at least at the circumferential edge of the flexible support element 202. As there is a close contact between the flexible support element 202 and the substrate W, the conditioning fluid in the conditioning fluid space 221 can be effectively used for temperature conditioning of the substrate W over its complete surface area.

[0124] The extendible seal 222 may be made of any suitable material. The material should be substantially fluid-tight and the extendible seal 222 has to withstand the pressure difference between the pressure in the conditioning fluid space 221 and the pressure in the environment of the substrate support 200. The extendible seal 222 shown in Figures 11A and 11B has a bellows configuration. In other embodiments, the extendible seal 222 may have other configurations such as telescopic elements, elastically deformable elements, or other suitable configurations to close a gap between the between the main support body 201 and the flexible support element 202.

[0125] The temperature conditioning device of Figures 11 A and 1 IB provides a full-surface thermal contact to the flexible support element 202. This enables the use of non-turbulent water flow and lower in-plane heat conductivity of the flexible support element 202 for wafer conditioning and uniformity. Furthermore, there is provided a large conditioning fluid volume below the flexible support element

[0126] It will be appreciated that the principles of the present invention can be applied to metrology or lithographic tools and clamping systems that employ electrostatic clamps. In such a case, rather than controlling the flow rate of an evacuation flow, other relevant parameters such as the voltage applied to the electrostatic clamp may be controlled.

[0127] Although specific reference may be made in this text to the use of a metrology system in the context of the manufacture of ICs, it should be understood that the metrology system described herein may have other applications, such as in 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. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion", respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and / or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains one or multiple processed layers.

[0128] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications.

[0129] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described.

[0130] The descriptions above are intended to be illustrative, 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 out below.

Claims

CLAIMS1. A substrate support configured to support a substrate, comprising: a flexible support element, comprising a first side to support the substrate; and a first clamping device to clamp the flexible support element on the substrate; wherein the flexible support element has a flexibility that allows the flexible support element to adapt its shape to the substrate having a non-planar shape by a clamping force of the first clamping device when clamping the flexible support element on the substrate with the first clamping device.

2. The substrate support of claim 1 , wherein the substrate support comprises a main support body to support the flexible support element, desirably wherein the main support body has a support surface and wherein the flexible support element comprises a second side to be supported on the support surface of the main support body, wherein the substrate support comprises a second clamping device to clamp the flexible support element on the main support body.

3. The substrate support of claim lor 2, wherein the flexibility of the flexible support element is larger than a flexibility of the substrate, and / or wherein the main support body is rigid, and / or wherein the first clamping device comprises a first vacuum clamping device.

4. The substrate support of claim 2 or 3, wherein the second clamping device comprises a second vacuum clamping device, desirably wherein one or more seals are provided between the flexible support element and the main support body to create one or more vacuum clamp spaces of the second vacuum clamping device, desirably wherein at least one of the one or more seals is an extendible seal to accommodate spacing differences between the main support body and the flexible support element due to deformation of the flexible support element.

5. The substrate support of any of the preceding claims, wherein the first clamping device comprises one, two or more first clamping zones that can be individually activated to exert a clamping force between the substrate and the flexible support element, desirably wherein the first clamping zones comprise two or more concentric rings.

6. The substrate support of any of the preceding claims, wherein the second clamping device comprises one, two or more second clamping zones that can be individually activated to exert a clamping force between the main support body and the flexible support element, desirably wherein the second clamping zones comprise two or more concentric rings.

7. The substrate support of any of the preceding claims, wherein the first side of the flexible support element comprises a plurality of first burls to support the substrate, and / or wherein the second side of the flexible support element comprises a plurality of second burls arranged to support the flexible support element on the support surface of the main support body.

8. The substrate support of any of the preceding claims, wherein the flexible support element comprises a plurality of burl elements, wherein each burl element comprises a first burl extending at the first side of the flexible support element and a second burl extending at the second side of the flexible support element, wherein the burl elements are made of a first material and wherein flexible support element comprises a second material, wherein the burl elements are connected to each other with the second material, wherein the second material is more flexible than the first material, desirably wherein the burl elements are rigid elements such that each combination of the first burl and the second burl forms a supporting pillar to support the substrate via the flexible support element on the main support body.

9. The substrate support of any of the preceding claims, wherein the substrate support comprises or is connected to a temperature conditioning device to condition a temperature of the substrate, desirably wherein the flexible support element comprises or is placed against a temperature conditioning conduit or a temperature conditioning space of the temperature conditioning device, and / or wherein the flexible support element comprises one or more sensors to determine a shape of the flexible support element.

10. A substrate support system comprising the substrate support of any of the preceding claims.

11. The substrate support system of claim 10, wherein the substrate support comprises at least one controller to control the first clamping device and the second clamping device, wherein the at least one controller is arranged to: activate the first clamping device to clamp the flexible support element on the substrate, and subsequently, activate the second clamping device to clamp the flexible support element and the substrate clamped thereon on the main support body.

12. The substrate support system of claim 10 or 11, wherein the first clamping device comprises one, two or more first clamping zones that can be individually activated to exert a clamping force between the substrate and the flexible support element, wherein the at least one controller is arranged to individually control the clamping forces in the respective first clamping zones, and / or wherein thesecond clamping device comprises one, two or more second clamping zones that can be individually activated to exert a clamping force between the substrate and the flexible support element, wherein the at least one controller is arranged to individually control the clamping forces in the respective second clamping zones.

13. The substrate support system of any of the claims 10-12, wherein the substrate support system comprises a temperature conditioning device to condition a temperature of the substrate to which the flexible support element is clamped.

14. A method to clamp a substrate on the substrate support of any of the claims 2-9, the method comprising the steps of: clamping with the first clamping device the substrate on the flexible support element, while allowing the flexible support element to adapt its shape to the substrate having a non-planar shape by a clamping force of the first clamping device; and while the substrate is clamped on the flexible support element, clamping with the second clamping device the flexible support element and the substrate clamped thereon on the main support body.

Images