Lithographic apparatus and method for controlling a substrate support

Abstract

The lithographic apparatus comprises: a substrate support configured to support a substrate, the substrate support having an opening configured to extract a fluid from a position proximate to an edge of the substrate; at least one processing system configured to process the substrate, the processing comprising measuring the substrate or moving the substrate relative to the substrate support; and a controller configured to control the application of negative pressure to the at least one processing system and the opening, the controller being adapted for each processing system to start applying negative pressure to the opening to extract the fluid from a position proximate to the edge of the substrate, to control the processing system to process the substrate, and to stop applying negative pressure so that the processing system at least partially processes the substrate while the negative pressure is being applied.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to European Application No. 23155342.1 filed February 7, 2023, European Application No. 23175105.8 filed May 24, 2023, and European Application No. 23183980.4 filed July 6, 2023, which applications are incorporated by reference in their entireties into this specification.

[0002] The present invention relates to a lithographic apparatus comprising a substrate support configured to support a substrate, a method for controlling the substrate support, and a method for manufacturing a device including the method for controlling the substrate support. [Background technology]

[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 referred to as a "design layout" or "design") from a patterning device (e.g. a mask) onto a layer of radiation-sensitive material (resist) provided on the substrate (e.g. a wafer). Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning a radiation beam across the substrate in a given direction (the "scan" direction) while synchronously scanning the substrate parallel to or anti-parallel to this direction.

[0004]

[0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements have continually decreased, while the amount of functional elements, such as transistors, per device has steadily increased for decades, following a trend colloquially known as "Moore's Law." To keep up with Moore's Law, the semiconductor industry pursues technologies that enable the creation of smaller and smaller features. To project a pattern onto a substrate, a lithography apparatus may 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.

[0005]

[0005] Further improvement in resolution of smaller features can be achieved by providing an immersion fluid with a relatively high refractive index, such as water, over the substrate during exposure. The effect of the immersion fluid is to allow imaging of smaller features, since the exposure radiation will have a shorter wavelength in the fluid than in a gas. The effect of the immersion fluid can also be thought of as increasing the effective numerical aperture (NA) of the system and increasing the depth of focus.

[0006]

[0006] The immersion fluid may be confined to a localized area between the projection system of the lithographic apparatus and the substrate by the fluid handling structure. Summary of the Invention

[0007]

[0007] In a semiconductor manufacturing process, a substrate is supported on a substrate support, specifically, on a plurality of burls that protrude from a surface of the substrate support.

[0008]

[0008] The immersion fluid is extracted to prevent it from reaching underneath the substrate. However, the extraction of the immersion fluid may cause an undesirable thermal load on one or more components of the system.

[0009] It is an object of the present invention to reduce the undesirable heat load caused by extraction of immersion fluid and / or to reduce the variation in heat load from substrate to substrate.

[0010]

[0010] According to the present invention, a substrate support configured to support a substrate, the substrate support comprising an opening configured to extract a fluid; at least one processing system configured to process the substrate, the processing comprising measuring the substrate or moving the substrate relative to the substrate support; a controller configured to control application of negative pressure to at least one treatment system and the opening, the controller including, for each treatment system: to initiate application of negative pressure to the opening to extract the fluid; to control a processing system to process a substrate; and a controller adapted to stop applying the negative pressure so that the processing system at least partially processes the substrate while the negative pressure is being applied; There is provided a lithographic apparatus comprising:

[0011]

[0011] According to the present invention there is also provided a method for controlling a substrate support of a lithographic apparatus, the method comprising: supporting a substrate on a substrate support; For each of at least one process performed on the substrate, where the process comprises measuring the substrate or moving the substrate relative to the substrate support: commencing application of a negative pressure to the opening in the substrate support to extract the fluid; performing a process on the substrate; ceasing the application of the negative pressure so that the processing system at least partially processes the substrate while the negative pressure is applied; Equipped with.

[0012]

[0012] The present invention also provides a method for manufacturing a device, including a method for controlling a substrate support of a lithographic apparatus.

[0013] Further embodiments, features, and advantages of the present invention, as well as the structure and operation of the various embodiments, features and advantages of the present invention, are described in detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0014]

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

[0015] [Figure 1] 1 shows a schematic overview of a lithographic apparatus; [Figure 2-3] 1 depicts, in cross-section, two different versions of a fluid handling system for use in a lithographic apparatus; [Figure 4] 1 illustrates a substrate support of a lithographic apparatus in cross section; [Figure 5] 1 illustrates in cross section an alternative substrate support for a lithographic apparatus in a clamped state; [Figure 6] 3 is a flow chart showing substrate processing steps.

[0016]

[0015] Features shown in the drawings are not necessarily to scale, and the illustrated size and / or arrangement is not limiting. It will be understood that the drawings include optional features that may not be essential to the invention. Also, not all features of a device may be illustrated in each drawing, and only some of the components relevant to the description of a particular feature may be shown. DETAILED DESCRIPTION OF THE INVENTION

[0017]

[0016] 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).

[0018]

[0017] As used herein, the terms "reticle," "mask," or "patterning device" may be broadly interpreted to refer to a 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" may also be used in this context. Besides the classic mask (transmissive or reflective mask, binary mask, phase-shifting mask, hybrid mask, etc.), examples of other such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0019] 1 schematically depicts a lithographic apparatus comprising: an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or DUV radiation), a mask support (e.g. 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 substrate support (e.g. substrate table) WT constructed to hold a substrate (e.g. resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate support WT according to certain parameters, and a projection system (e.g. refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W.

[0020]

[0019] In operation, the illumination system IL receives a radiation beam B from a radiation source SO, for example via a beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic and / or other types of optical components, or any combination thereof, for directing, shaping and / or controlling the radiation. The illuminator IL may be used to condition the radiation beam B so that it has a desired spatial and angular intensity distribution in its cross-section in the plane of the patterning device MA.

[0021]

[0020] The term "projection system" PS as used herein should be interpreted broadly as encompassing various types of projection systems, including refractive optical systems, catadioptric optical systems, anamorphic optical systems, magnetic optical systems, electromagnetic optical systems, and / or electrostatic optical systems, or any combination thereof, as appropriate to the exposure radiation used and / or other factors such as the use of an immersion liquid or a vacuum. Where the term "projection lens" is used herein, this may be considered as synonymous with the more general term "projection system" PS.

[0022]

[0021] The lithographic apparatus is of a type in which at least a portion of the substrate W may be covered by an immersion liquid having a relatively high refractive index, e.g. water, so as to fill an immersion space 11 between the projection system PS and the substrate W, which is also referred to as immersion lithography. Further information about immersion techniques can be found in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0023] The lithographic apparatus may be of a type that includes two or more substrate supports WT (also referred to as "dual stage"). In such a "multi-stage" machine, the substrate supports WT may be used in parallel, and / or while a substrate W on one substrate support WT is being used to expose a pattern on that substrate W, preparation steps for a subsequent exposure of the substrate W may be performed on a substrate W located on another one of the substrate supports WT.

[0024] In addition to the substrate support WT, the lithographic apparatus may include a measurement stage (not shown in the drawings). The measurement stage is arranged to hold a sensor and / or a cleaning device. The sensor may be arranged to measure a property of the projection system PS or a property of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning device may be arranged to clean part of the lithographic apparatus, for example part of the projection system PS or part of the system for providing immersion liquid. The measurement stage may move below the projection system PS when the substrate support WT is spaced apart from the projection system PS.

[0025] In operation, the radiation beam B is incident on the patterning device MA, for example a mask held on the mask support MT, and is patterned by a pattern (design layout) present on the 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. Using the second positioner PW and the position measurement system IF, the substrate support WT may be accurately moved, for example to position different target portions C at focused and aligned positions in the path of the radiation beam B. Similarly, the first positioner PM, and possibly further position sensors (not explicitly shown in FIG. 1 ), may be used to accurately position the patterning device MA with respect to the path of the radiation beam B. The patterning device MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. The illustrated substrate alignment marks P1, P2 occupy dedicated target portions, but may also be located in spaces between the target portions. When substrate alignment marks P1, P2 are located between target portions C, they are called scribe-lane alignment marks.

[0026] To clarify the invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes: x, y, and z. Each of the three axes is orthogonal to the other two. Rotation about the x-axis is referred to as Rx rotation. Rotation about the y-axis is referred to as Ry rotation. Rotation about the z-axis is referred to as Rz rotation. The x- and y-axes define a horizontal plane, while the z-axis is vertical. The Cartesian coordinate system is not limiting of the invention and is used for clarity only. Alternatively, 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, the z-axis may have a component along the horizontal plane.

[0027] Immersion techniques have been introduced into lithography systems to enable improved resolution of smaller features. In an immersion lithography apparatus, a layer of immersion liquid, having a relatively high refractive index, is interposed in an immersion space 11 between the apparatus' projection system PS (through which a patterned beam is projected towards the substrate W) and the substrate W. The immersion liquid covers at least that part of the substrate W below the final element of the projection system PS. Thus, at least the part of the substrate W that is to be exposed is immersed in the immersion liquid.

[0028] 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 immersion systems, the UPW is often purified and may undergo additional processing steps before being supplied to the immersion space 11 as the immersion liquid. Besides water, other liquids with high refractive indices, for example hydrocarbons such as fluorocarbons, and / or aqueous solutions, can be used as the immersion liquid. It is also envisioned that other fluids than liquids will be used in immersion lithography.

[0029]

[0028] In this specification, the description refers to localized immersion where, in use, the immersion liquid is confined to an immersion space 11 between the final element and a surface facing the final element. This facing surface is the surface of the substrate W or a surface of the support stage (or substrate support WT) that is coplanar with the surface of the substrate W. (Note that in the following text, references to the surface of the substrate W may additionally or alternatively refer to the surface of the substrate support WT, and vice versa, unless otherwise stated.) A fluid handling structure IH present between the projection system PS and the substrate support WT is used to confine the immersion liquid to the immersion space 11. The immersion space 11, filled with immersion liquid, is smaller than the top surface of the substrate W when viewed from above, and the immersion space 11 remains substantially stationary relative to the projection system PS while the substrate W and substrate support WT move underneath.

[0030] Other immersion systems are also envisaged, such as unconfined immersion systems (so-called "all wet" immersion systems) and bath immersion systems. In an unconfined immersion system, the immersion liquid covers more than the surface below the final element. The liquid outside the immersion space 11 is present as a thin liquid film. The liquid may cover the entire surface of the substrate W, or even the substrate W and a substrate support WT that is coplanar with the substrate W. In a bath-type system, the substrate W is fully immersed in a bath of immersion liquid.

[0031] The fluid handling structure IH is a structure that supplies immersion liquid to and removes immersion liquid from the immersion space 11, thereby confining the immersion liquid in the immersion space 11. It includes features that are part of a fluid supply system. The arrangement disclosed in PCT Patent Application Publication No. WO 99 / 49504 is an early fluid handling structure that comprises pipes that supply or remove immersion liquid from the immersion space 11 and that operate in response to relative movement of a stage below the projection system PS. In more recent designs, the fluid handling structure extends along at least part of the boundary of the immersion space 11 between the final element of the projection system PS and the substrate support WT or substrate W, so as to partly define the immersion space 11.

[0032] The fluid handling structure IH may have a range of different functions. Each function may be derived from a corresponding feature that enables the fluid handling structure IH to achieve that function. The fluid handling structure IH may be referred to by a number of different terms, each referring to a function, such as barrier member, seal member, fluid supply system, fluid removal system, liquid confinement structure, etc.

[0033]

[0032] An immersion liquid may be used as the immersion fluid. In that case, the fluid handling structure IH may be a liquid handling system. In accordance with the above, references in this paragraph to features defined in relation to a fluid may be understood to include features defined in relation to a liquid.

[0034] The lithographic apparatus has a projection system PS. During exposure of a substrate W, the projection system PS projects a patterned beam of radiation onto the substrate W. To reach the substrate W, the path of the radiation beam B passes from the projection system PS through immersion liquid that is confined by a fluid handling structure IH between the projection system PS and the substrate W. The projection system PS has a lens element at the end of the path of the beam, which lens element comes into contact with the immersion liquid. This lens element that comes into contact with the immersion liquid may be referred to as the "final lens element" or "final element". The final element is at least partly surrounded by the fluid handling structure IH. The fluid handling structure IH may confine immersion liquid below the final element and above a facing surface.

[0035] As shown in Figure 1, the lithographic apparatus comprises a controller 500. The controller 500 is configured to control the substrate support WT.

[0036] 2 illustrates schematically 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 an immersion space 11 between the final element of the projection system PS and the substrate support WT or substrate W. The fluid handling structure IH is substantially stationary in the XY plane relative to the projection system PS, but there may be some relative movement in the Z direction (along the optical axis). In one example, a seal is formed between the fluid handling structure IH and the surface of the substrate W, and this may be a contactless seal such as a gas seal (such a system comprising a gas seal is disclosed in EP 1 420 298 A) or a liquid seal.

[0037] The fluid handling structure IH at least partly confines immersion liquid to an immersion space 11 between the final element of the projection system PS and the substrate W. The immersion space 11 is formed at least partly by the fluid handling structure IH positioned below and surrounding the final element of the projection system PS. Immersion liquid is introduced into the immersion space 11 below the projection system PS and in the fluid handling structure IH by one of the liquid openings 13. Immersion liquid may be removed by another of the liquid openings 13. Immersion liquid may be introduced into the immersion space 11 through at least two liquid openings 13. Which of the liquid openings 13 is used to supply immersion liquid, and optionally which is used to remove immersion liquid, may depend on the direction of movement of the substrate support WT.

[0038] The immersion liquid may be confined in the immersion space 11 by a contactless seal such as a gas seal 16 formed by gas forming, during use, between the bottom of the fluid handling structure IH and the surface of the substrate W. The gas in the gas seal 16 is provided under pressure to the gap between the fluid handling structure IH and the substrate W via inlet 15. The gas is extracted via outlet 14. The overpressure at the gas inlet 15, the vacuum level at the outlet 14 and the geometry of the gap are configured so that there is a high velocity inward gas flow that confines the immersion liquid. Such a system is disclosed in US Patent Application Publication No. 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.

[0039]

[0038] Figure 3 is a cross-sectional side view illustrating a further liquid supply or fluid handling system. The arrangement shown in Figure 3 and described below may be applied to the lithographic apparatus shown in Figure 1 and described above. 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 immersion space 11 between the final element of the projection system PS and the substrate support WT or substrate W.

[0040] The fluid handling structure IH at least partly confines immersion liquid to an immersion space 11 between the final element of the projection system PS and the substrate W. The immersion space 11 is formed at least in part 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-shaped and has a plurality of holes (i.e. openings or pores). The porous member 33 may be a mesh plate having a multitude of small holes 84 formed in a network. Such a system is disclosed in US Patent Application Publication No. 2010 / 0045949 A1, which is incorporated herein by reference in its entirety.

[0041] The body member 53 is provided with supply ports 72 that can supply immersion liquid to the immersion space 11, and recovery ports 73 that can recover immersion liquid from the immersion space 11. The supply ports 72 are connected to liquid supply devices 75 via passages 74. The liquid supply devices 75 are able to supply immersion liquid to the supply ports 72 through the corresponding passages 74. The recovery ports 73 are able to recover immersion liquid from the immersion space 11. The recovery ports 73 are connected to liquid recovery devices 80 via passages 79. The liquid recovery device 80 recovers, via the passages 79, the immersion liquid recovered via the recovery ports 73. The porous member 33 is arranged in the recovery ports 73. By performing a liquid supply operation using the supply ports 72 and a liquid recovery operation using the porous member 33, an immersion space 11 is formed between the projection system PS and the fluid handling structure IH on the one hand, and between the projection system PS and the substrate W on the other hand.

[0042]

[0041] Figure 4 shows a schematic representation of a substrate support 300 of a lithographic apparatus. The arrangement shown in Figure 4 and described below may be applied to the lithographic apparatus shown in Figure 1 and described above. Figure 4 shows a cross section of the substrate support 300 and the substrate W.

[0043] The support body 321 is the part of the substrate support 300 that physically supports the underside of the substrate W. The distal ends of the burls 341 form a plane on which the underside of the substrate W is supported. The underside of the substrate W contacts the distal ends of the burls 341. The burls 341 are disposed on the upper side of the support body 321.

[0044] In an embodiment, the substrate support 300 comprises one or more conditioning channels 61 of a thermal conditioner for thermally conditioning the substrate support 300 and / or the substrate W. A gap 5 exists between the edge of the substrate W and the edge of the substrate support 300. When the edge of the substrate W is being imaged, or at other times, such as when the substrate W is first moving under the projection system PS (as described above), the immersion space 11, which has been filled with liquid by (for example) the fluid handling structure IH, will pass at least partially over the gap 5 between the edge of the substrate W and the edge of the substrate support 300. This can cause immersion liquid from the immersion space 11 to enter the gap 5.

[0045] The substrate W is held by a support body 321 (e.g. a pimple or burl table) that comprises one or more burls 341 (i.e. protrusions from its surface). The support body 321 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 support 300 helps to ensure that the substrate W is held firmly in place. However, if immersion liquid gets between the substrate W and the support body 321, this may cause difficulties, especially when unloading the substrate W.

[0046] To deal with immersion liquid entering the gap 5, at least one drain 10, 12 is provided at the edge of the substrate W to remove immersion liquid that enters the gap 5. Although two drains 10, 12 are shown in the embodiment of Figure 4, there may be only one drain or more than two drains. In one embodiment, each of the drains 10, 12 is annular so that it surrounds the entire periphery of the substrate W.

[0047] The main function of the first drain 10 (radially outward from the edge of the substrate W / support body 321) is to help prevent gas bubbles from entering the immersion space 11 in which the immersion liquid of the fluid handling structure IH is present. Such bubbles could have a detrimental effect 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 fluid handling structure IH. If gas were to escape into the immersion space 11, it could result in bubbles floating in the immersion space 11. Such bubbles could cause imaging errors if they are in the path of the radiation beam B. The first drain 10 is configured to remove gas from the gap 5 between the edge of the substrate W and the edge of the recess in the substrate support 300 in which the substrate W is placed. The edge of the recess in the substrate support 300 may be defined by a cover ring 301 that is optionally separate from the support body 321 of the substrate support 300. The cover ring 301 may be shaped as a ring when viewed from above and surrounds the outer edge of the substrate W. The first drain 10 extracts mainly gas and a small amount of immersion liquid.

[0048] The second drain 12 (radially inward of the edge of the substrate W / support body 321) is provided to help prevent immersion liquid progressing from the gap 5 underneath the substrate W from interfering with efficient release of the substrate W from the substrate support WT after imaging. The provision of the second drain 12 reduces or eliminates problems that can arise due to liquid progressing underneath the substrate W. The second drain 12 is configured to extract the two-phase fluid.

[0049] 4, in one embodiment, the lithographic apparatus includes a first extraction channel 102 for passing the two-phase flow. The first extraction channel 102 is formed in a block, for example, a support body 321. The first and second drains 10, 12 are each provided with a respective opening 107, 362 and a respective extraction channel 102, 113. The extraction channel 102, 113 is in fluid communication with the respective opening 107, 362 through a respective passage 103, 114.

[0050] 4, the cover ring 301 has an upper surface. The upper surface extends circumferentially around the substrate W on the support body 321. When the lithographic apparatus is in use, the fluid handling structure IH moves relative to the substrate support 300. During this relative movement, the fluid handling structure IH moves across the gap 5 between the cover ring 301 and the substrate W. In an embodiment, the relative movement is caused by the substrate support 300 moving below the fluid handling structure IH. In an alternative embodiment, the relative movement is caused by the fluid handling structure IH moving above the substrate support 300. In a further alternative embodiment, the relative movement is provided by both movement of the substrate support 300 below the fluid handling structure IH and movement of the fluid handling structure IH above the substrate support 300. In the following description, movement of the fluid handling structure IH is used to mean relative movement of the fluid handling structure IH with respect to the substrate support 300.

[0051] 4, the substrate support 300 further includes a plurality of seals 332, 333, and 334. The seals 332, 333, and 334 are circumferential rings protruding from the substrate support 300. In this configuration, there are at least three seals: an inner seal 334, a middle seal 332 radially outward of the inner seal 334, and an outer seal 333 radially outward of the middle seal 332. The inner seal 334 is an example of a first circumferential wall, the middle seal 332 is an example of a third circumferential wall, and the outer seal 333 is an example of a third circumferential wall. In one embodiment, in the substrate support 300, the burls protruding from the middle seal 332 are mini-burls 342 having a smaller diameter than the other burls 341 protruding from the surface. The mini-burls 342 are optional.

[0052] The plurality of seals 332, 333, 334 define a plurality of gutters 354, 352 between the substrate support 300 and the substrate W.

[0053] 4, the substrate support 300 further includes an opening 364 between the inner seal 334 and the mid-seal 332 (in the gutter 354). The opening 364 may be configured to supply gas to and extract gas from the gutter 354.

[0054] The area radially inward of the inner seal 334 is a clamping area 353. In one embodiment, the substrate support 300 may further comprise a clamping opening radially inward of the inner seal 334 (in the clamping area 353, not shown) configured to extract gas from the clamping area 353.

[0055]

[0054] Figure 5 illustrates in cross section an alternative substrate support 300 of a lithographic apparatus. The substrate support 300 is illustrated in a clamped state. The configuration shown in Figure 5 and described below may be applied to the lithographic apparatus shown in Figure 1 described above. Figure 5 is a cross section of the substrate support 300 and the substrate W. Features of the substrate support 300 shown in Figure 5 may be those described above with reference to Figure 4. Additional features or features that differ from those shown in Figure 4 are described below.

[0056] 4, the substrate support 300 includes a support body 321. The support body 321 is provided with a plurality of burls 341. When the substrate W is supported by the substrate support 300, the substrate W is in direct contact with the support body 321. The support body 321 is the part of the substrate support 300 that physically supports the underside of the substrate W. The distal ends of the burls 341 form a plane on which the underside of the substrate W is supported. The underside of the substrate W is in contact with the distal ends of the burls 341. The burls 341 are arranged on the upper side of the support body 321.

[0057] 5, the substrate support 300 includes a plurality of seals 331, 332, 333, and 334. These seals 331, 332, 333, and 334 are circumferential rings that protrude from the substrate support 300. In one embodiment, there are at least four seals: an inner seal 331, an inner middle seal 334 that is radially outward of the inner seal 331, a middle seal 332 that is radially outward of the inner middle seal 334, and an outer seal 333 that is radially outward of the middle seal 332. The inner seal 331 is an example of a first circumferential wall, the inner middle seal 334 is an example of a second circumferential wall, the middle seal 332 is an example of a third circumferential wall, and the outer seal 333 is an example of a fourth circumferential wall. 5, the inner seal 331, inner mid-seal 334, mid-seal 332, and outer seal 333 are circumferential rings that protrude from the surface of the support body 321. In one embodiment, in the substrate support 300, the burls protruding from the mid-seal 332 are mini-burls 342 that have a smaller diameter than the other burls 341 protruding from the surface. The mini-burls 342 are optional.

[0058] The multiple seals 331, 332, 333, and 334 define multiple regions between the substrate support 300 and the substrate W. The multi-function gutter 351 is a region extending circumferentially around the substrate support 300 between the inner seal 331 and the inner mid-seal 334. The peripheral gutter 354 is a region extending circumferentially around the substrate support 300 between the inner mid-seal 334 and the mid-seal 332. The fluid extraction gutter 352 is a region extending circumferentially around the substrate support 300 between the mid-seal 332 and the outer seal 333. The peripheral gutter 354 is typically at ambient pressure, but may be at a pressure lower than ambient pressure or higher than the pressure in the fluid extraction gutter 352.

[0059] 5, the support body 321 further includes a plurality of openings 361, 364, and 362. These openings are a multifunctional opening 361 disposed between the inner seal 331 and the inner mid-seal 334 (in the multifunctional gutter 351), a peripheral opening 364 disposed between the inner mid-seal 334 and the mid-seal 332 (in the peripheral gutter 354), and a fluid extraction opening 362 disposed between the mid-seal 332 and the outer seal 333 (in the fluid extraction gutter 352). The multifunctional opening 361 is an example of a first opening, the peripheral opening 364 is an example of a second opening, and the fluid extraction opening 362 is an example of a third opening.

[0060] In one embodiment, the multi-functional opening 361 is configured to supply and extract gas from the multi-functional gutter 351. However, the multi-functional opening 361 may be configured only to supply gas or only to extract gas. The peripheral opening 364 may be configured to be in fluid communication with ambient pressure. Ambient pressure may be provided from the atmosphere or from a fluid source within the system. The peripheral opening 364 may also be configured to be in fluid communication with a positive pressure (a pressure greater than ambient pressure). The peripheral opening 364 may also be configured to be in fluid communication with a pressure less than ambient pressure but greater than the pressure on the opposite side of the inner mid-seal 334 and the mid-seal 332. The fluid extraction opening 362 is configured to extract fluid from the fluid extraction gutter 352. The fluid extraction opening 362 may be part of a drain system comprising multiple channels and passages configured to contain a fluid, such as the second drain 12 of the substrate support 300.

[0061] 5 , the area radially inward of the inner seal 331 is the clamping region 353. In one embodiment, the support body 321 may further comprise a clamping opening 363 radially inward (within) the inner seal 331 configured to extract gas from the clamping region 353. The clamping opening 363 is configured to extract gas from a position proximate to the center of the substrate W or radially inward of the fluid extraction gutter 352 and / or peripheral gutter 354 relative to the center of the substrate W.

[0062] 5, the multi-functional opening 361 may extract gas from the multi-functional gutter 351, thereby establishing a negative pressure within the multi-functional gutter 351. This means that a clamping force is applied to the underside of the substrate W at a portion corresponding to the multi-functional gutter 351, as well as the clamping region 353. Alternatively, the multi-functional opening 361 may be closed so that it is not in fluid communication with either ambient pressure, overpressure, or negative pressure.

[0063] In the clamped state, the peripheral opening 364 and the fluid extraction openings 362 are open. That is, the peripheral opening 364 is in fluid communication with ambient pressure, and the fluid extraction openings 362 extract fluid from the fluid extraction gutter 352. Alternatively, the peripheral opening 364 may be in fluid communication with a positive pressure source. The peripheral opening 364 may also be configured to be in fluid communication with a pressure that is less than ambient pressure but greater than the pressure on the other side of the inner mid-seal 334 and the mid-seal 332. Figure 5 shows that when the substrate W is in the clamped state, immersion fluid that has flowed through the gap 5 between the substrate W and the cover ring 301 also passes between the outer seal 333 and the underside of the substrate W and is present in the fluid extraction gutter 352. It is this immersion fluid that is extracted by the fluid extraction openings 362. The extraction pressure of the fluid extraction openings 362, the mid-seal 332, and the ambient pressure in the peripheral gutter 354 prevent immersion fluid from flowing radially inward of the mid-seal 332.

[0064] 4 and 5, the peripheral opening 364 is configured to supply gas towards the clamping region 353. The supply of gas reduces the possibility of immersion fluid flowing inward to reach the multi-functional gutter 351 or the multi-functional opening 361. In the configuration shown in Figure 5, when the substrate support 300 is in the clamped state, two seals (the middle seal 332 and the inner middle seal 334) between the multi-functional gutter 351 and the immersion fluid reduce the possibility of immersion fluid flowing inward to reach the multi-functional gutter 351 or the multi-functional opening 361.

[0065] Immersion fluid may be prevented from flowing inwardly even when extraction of immersion fluid through the fluid extraction openings 362 is stopped or significantly reduced. The extraction of immersion fluid through the fluid extraction openings 362 may be controlled, for example switched on and off or increased or decreased, without significantly affecting the likelihood of immersion fluid flowing undesirably inwardly beneath the substrate W.

[0066] The fluid extraction openings 362 are configured to extract fluid from a position proximate to the edge of the substrate W. The fluid extraction openings 362 may extract both liquid and gas. For example, when the immersion fluid is a liquid, the fluid extraction openings 362 may extract the liquid together with some gas. The fluid extraction openings 362 may, for example, extract gas supplied through the peripheral openings 364.

[0067] In one embodiment, the inner seal 331, the inner mid-seal 334, the multi-function gutter 351, the peripheral gutter 354, the multi-function opening 361, and the peripheral opening 364 may be optional.

[0068] 6 is a flow chart illustrating processing performed on a substrate W. In an embodiment, the lithographic apparatus comprises at least one processing system configured to process the substrate W. For example, in an embodiment, the lithographic apparatus comprises an exposure station 91. The exposure station 91 may comprise an exposure system (not shown) configured to expose the substrate W. The exposure system may comprise, for example, the components shown in FIG. 1. The exposure station 91 may further comprise at least one device alignment system configured to align a patterning device MA.

[0069] In one embodiment, the lithographic apparatus comprises a measurement station 92. The measurement station 92 may comprise at least one measurement system. The measurement system is configured to measure the substrate W. For example, the measurement station 92 may comprise a substrate mapper (not shown) configured to measure the height of a surface of the substrate W across the substrate W. The measurement station 92 may comprise at least one substrate aligner (not shown) configured to align the substrate W. In one embodiment, the measurement station 92 comprises at least one substrate movement system (not shown). The substrate movement system is configured to move the substrate W relative to the substrate support 300. The substrate movement system may be configured to load the substrate W onto the substrate support 300. The substrate movement system may be configured to unload the substrate W from the substrate support 300.

[0070]

[0069] The following describes the processing performed on the substrate W. In step 40, the substrate W may be loaded onto the substrate support 300. In one embodiment, a substrate transfer system is configured to load the substrate W onto the substrate support 300.

[0071] 6, processing of the substrate W continues with step 41. In step 41, the substrate support 300, on which the substrate W is loaded, is aligned. The position of the substrate support 300 is measured. During this initial alignment step, the location of the substrate support 300 relative to the projection system PS is determined. The position of the substrate support 300 is measured with a certain degree of accuracy. In one embodiment, a measurement system, such as a stage aligner (not shown), may perform step 41.

[0072] 6, processing of the substrate W continues with step 42. In step 42, the shape of the substrate W may be measured. For example, the height of different parts of the top surface of the substrate W may be measured. In one embodiment, step 42 may be performed by a measurement system, such as a level measurement device (not shown).

[0073] 6, processing of the substrate W continues at step 43. At step 43, the alignment of the substrate W may be determined. In one embodiment, step 43 may be performed by a coarse measurement system, which may be referred to as a coarse substrate aligner (not shown).

[0074] 6, processing of the substrate W continues with step 44. In step 44, the height of the top surface of the substrate W may be measured more accurately than in step 42. In one embodiment, step 44 is performed by a substrate mapper.

[0075] 6, processing of the substrate W continues at step 45. At step 45, the location of the substrate W is determined more accurately than at step 43. In one embodiment, step 45 may be performed by a precision measurement system, which may be referred to as a fine substrate aligner (not shown).

[0076] 6, processing of the substrate W continues in step 46. In step 46, the substrate W on the substrate support 300 is provided to the exposure system. The substrate W and substrate support 300 may be replaced with another substrate and substrate support used in a previous exposure process. The fluid handling structure IH and the substrate W may be moved relative to each other so that the fluid handling structure IH is above the substrate W.

[0077]

[0076] As shown in Figure 6, processing continues to step 47. In step 47, the mask support MT may be aligned. As shown in Figure 6, processing continues to step 48. In step 48, the patterning device MA may be aligned.

[0078] As shown in Figure 6, the processing of the substrate W continues to step 49. In step 49, the substrate W may be exposed. During the exposure process, the fluid handling structure IH may be above the substrate W. As shown in Figure 6, the processing of the substrate W continues to step 50. In step 50, the exposure process may be completed.

[0079] After the exposure process is completed, the fluid handling structure IH and the substrate W may be moved relative to each other so that the fluid handling structure IH is no longer above the substrate, and the process may continue with another iteration of step 46, in which case the substrate W and substrate support 300 are replaced in the exposure system with another substrate W and another substrate support to be exposed.

[0080] 6. Extraction may be switched on during exposure steps 49, 50. However, extraction may be switched off or at least reduced during one or more other processing steps to reduce undesirable heat load caused by extraction.

[0081] As mentioned above, the lithographic apparatus may comprise at least one processing system configured to process the substrate W. In an embodiment, the processing comprises measuring the substrate W or moving the substrate W relative to the substrate support 300. For example, the processing system may be a measurement system or a substrate movement system. An exposure system for exposing the substrate W is provided separately from the at least one processing system. The at least one processing system does not include an exposure system for exposing the substrate W.

[0082] In one embodiment, the controller 500 is configured to control at least one processing system and the application of negative pressure to the fluid extraction openings 362. In one embodiment, the controller 500 is adapted, for each processing system, to start applying negative pressure to the fluid extraction openings 362 to extract fluid from a location proximate to an edge of the substrate W, to control the processing system to process the substrate W, and to stop applying negative pressure to at least partially process the substrate W while the negative pressure is applied.

[0083] For example, in one embodiment, the processing system is a measurement system such as a substrate mapper and / or a fine substrate aligner. In one embodiment, the measurement system is configured to measure the height of a surface of the substrate W at a plurality of locations across the substrate W. For example, the measurement system may comprise a substrate mapper. In one embodiment, the measurement system is configured to measure the position of the substrate W in a plane parallel to the substrate W. For example, the measurement system may comprise a substrate aligner.

[0084] In one embodiment, the controller 500 is adapted to initiate application of negative pressure to the fluid extraction openings 362 to extract fluid from a location proximate to the edge of the substrate W. Before the controller 500 initiates application of negative pressure, no negative pressure is applied, or at least extraction of fluid through the fluid extraction openings 362 is significantly reduced. During this time, the heat load is reduced. When application of negative pressure is initiated, the heat load may increase.

[0085] When the application of negative pressure begins, the shape and / or position of the substrate W may be affected. For example, the edge of the substrate W may be lower than it was before the application of negative pressure began. When negative pressure is applied, the shape and / or position of the substrate W may be substantially the same as during the exposure process.

[0086] The controller 500 may be configured to stop applying the negative pressure so that the measurement system at least partially processes the substrate W while the negative pressure is being applied. The measurement system, such as a substrate mapper and / or a fine motion substrate aligner, may measure the substrate W in substantially the same conditions as the substrate W during exposure processing. This improves the accuracy and usefulness of the measurements.

[0087] The controller 500 may be configured to apply negative pressure when extraction of fluid is required through the fluid extraction openings 362. When extraction of fluid through the fluid extraction openings 362 is not required, the controller 500 may stop applying negative pressure to reduce any undesired heat load.

[0088] For example, extraction may be required so that measurement systems such as substrate mappers and / or fine motion substrate aligners measure the substrate W in the same state as during the exposure process, but for other processing steps it may not be important that the substrate W has the same configuration as during the exposure process.

[0089] For example, in one embodiment, the lithographic apparatus comprises a coarse measurement system (not shown) configured to measure the substrate W more coarsely than the measurement system used when extraction through the fluid extraction openings 362 is switched on. In one embodiment, the controller 500 is configured to control the coarse measurement system to stop applying negative pressure to the fluid extraction openings 362 before the coarse measurement system measures the substrate W, and to coarsely measure the substrate W when the application of negative pressure is stopped.

[0090] 6, extraction through the fluid extraction openings 362 may be switched off while the coarse substrate aligner performs step 43 of coarsely measuring the substrate W. Extraction may then be switched on when the fine substrate aligner performs a more precise measurement of the substrate W in step 45. In the coarse measurement of step 43, the measurement is sufficiently coarse that it is inconsequential that the edge of the substrate W may curl slightly upwards due to fluid not being extracted through the fluid extraction openings 362 during measurement. By controlling extraction, an embodiment of the present invention is expected to achieve the advantage of reducing the heat load without significantly compromising the accuracy of the process performed on the substrate W.

[0091] In one embodiment, the controller 500 is adapted to start applying the negative pressure before the measurement system measures the substrate W, and to stop applying the negative pressure after the measurement system has finished measuring the substrate W. For example, in one embodiment, the application of the negative pressure is started before the substrate mapper performs step 44. The negative pressure may continue to be applied until after the fine substrate aligner performs step 45.

[0092] In one embodiment, the controller 500 is adapted to start applying the negative pressure at least a predetermined time before the measurement system measures the substrate W. The predetermined time may be selected so that there is sufficient time for the shape of the substrate W to be changed by extraction through the fluid extraction openings 362. There may be sufficient time for the substrate W to have the same shape as it had during the exposure process. In one embodiment, the controller 500 is adapted to start applying the negative pressure at least a predetermined time before the substrate mapper measures the substrate W.

[0093] In one embodiment, the controller 500 is adapted to stop applying the negative pressure a predetermined time after the measurement system has finished measuring the substrate W. This may help to reduce the possibility of the measurement being interrupted by unintentionally stopping the extraction prematurely. In one embodiment, the controller 500 is adapted to stop applying the negative pressure at least a predetermined time after the fine substrate aligner has measured the substrate W.

[0094] In one embodiment, at least one processing system comprises a substrate transfer system configured to move a substrate W relative to the substrate support 300. In one embodiment, the substrate transfer system is configured to unload the substrate W from the substrate support 300, for example in step 51. In one embodiment, the substrate transfer system is configured to load the substrate W onto the substrate support 300, for example in step 40.

[0095] During steps 51 and 40, extraction through the fluid extraction openings 362 may be switched on for part of the load / unload process. In the examples of the substrate mapper in step 44 and the fine substrate aligner in step 45 described elsewhere, extraction is switched on for the entire measurement process. In contrast, extraction may be switched on for only part of the load / unload process. Extraction may also be switched off for part of the load / unload process.

[0096] In an embodiment, the controller 500 is adapted for the substrate transfer system to start applying negative pressure after the substrate transfer system has started a sequence for moving the substrate W relative to the substrate support 300, and to stop applying negative pressure before the substrate transfer system has finished a sequence for moving the substrate W relative to the substrate support 300. The extraction may be switched on temporarily during loading and / or unloading of the substrate W to remove immersion fluid, such as liquid. The removal of immersion fluid may improve the performance of loading and / or unloading of the substrate W. The removal of immersion fluid may reduce wear on the substrate support 300 during loading and / or unloading.

[0097] In an embodiment, the lithographic apparatus comprises a positioner (not shown) configured to move the substrate support 300 relative to at least one processing system. In an embodiment, the controller 500 is adapted to control the positioner to move the substrate support 300 to the processing system before the processing system processes the substrate W, and to move the substrate support 300 from the processing system after the processing system has finished processing the substrate W.

[0098] For example, the positioner may move the substrate support 300 to the substrate transfer system with the substrate W loaded thereon. While the positioner is moving the substrate support 300 to the substrate transfer system, extraction through the fluid extraction openings 362 may be switched off to reduce heat load.

[0099] The substrate transfer system may then unload the substrate W from the substrate support 300 (i.e., step 51). During unloading of the substrate W, extraction through the fluid extraction openings 362 may be temporarily switched on, for example to remove immersion fluid. The substrate transfer system may then load another substrate W onto the substrate support 300 (i.e., step 40). During loading of the substrate W, extraction through the fluid extraction openings 362 may be temporarily switched on, for example to remove immersion fluid.

[0100] The positioner may then move the substrate support 300 to at least one measurement system for coarse measurement of the substrate W. While the positioner is moving the substrate support 300 to the coarse measurement system, extraction through the fluid extraction openings 362 may be switched off to reduce heat load. While the substrate support measurement, i.e., step 41, and the coarse measurement, i.e., steps 42-43, are performed on the substrate W, extraction through the fluid extraction openings 362 may be switched off to reduce heat load. While the substrate support measurement, i.e., step 41, and the coarse measurement, i.e., steps 42-43, are performed on the substrate W, the substrate W may be moving, although the substrate W remains stationary relative to the substrate support 300.

[0101] The positioner may then move the substrate support 300 to at least one measurement system for more precise measurements of the substrate W. While the positioner is moving the substrate support 300 to the precision measurement system, extraction through the fluid extraction openings 362 may be switched off to reduce heat load. While precision measurements, i.e., steps 44-45, are performed on the substrate W, extraction through the fluid extraction openings 362 may be switched on, so that the shape of the substrate that it will take during the exposure process can be measured more accurately. While precision measurements, i.e., steps 44-45, are performed on the substrate W, the substrate W may be moving, although it remains stationary relative to the substrate support 300.

[0102] The positioner may then move the substrate support 300 to the exposure system positioned below the fluid handling structure IH. While the positioner is moving the substrate support 300, extraction through the fluid extraction openings 362 may be switched off to reduce heat load. While positioning the substrate support 300, alignment of the mask support MT and the patterning device MA, i.e. steps 46 to 48, are performed, extraction through the fluid extraction openings 362 may be switched off to reduce heat load. In an embodiment, sensor measurements such as alignment of the mask support MT and the patterning device MA are performed via measuring TIS / ILLIAS / PARIS sensors located away from the substrate W. The sensors may be located near the substrate W. The sensors may comprise transmission image sensors (TIS), scanner integrated lens interferometers (ILIAS), and / or parallel ILIAS (PARIS).

[0103] The substrate W may then be exposed (i.e. steps 49-50). During exposure of the substrate W, extraction through the fluid extraction openings 362 may be switched on. After exposure is finished, there may be a variable amount of waiting time before another substrate support 300 loaded with another substrate W is positioned relative to the fluid handling structure IH. During the waiting time, extraction through the fluid extraction openings 362 may be switched off to reduce heat load.

[0104] Each process can be expected to take substantially the same time for different layers to be exposed and for different substrates. The maximum time variation from one layer to another can be expected to be the amount of waiting time mentioned above. In one embodiment, extraction through the fluid extraction openings 362 is switched off during this time. This allows the total amount of time that extraction is switched on to remain substantially equal across different substrates W and layers. An embodiment of the present invention is expected to increase the predictability of the amount of heat load that a substrate W will experience. Any heat load can have an undesirable effect on overlay. An embodiment of the present invention is expected to reduce overlay.

[0105] The shape of the substrate W may change depending on whether or not negative pressure is applied to an opening (e.g., fluid extraction opening 362). It is therefore expected that measurements made on the substrate W will differ depending on whether or not negative pressure is applied when the measurements are made. How the substrate W changes shape due to changes in negative pressure may be known and / or may be predicted. For example, the dependence of the shape of the substrate W on negative pressure may be determined by experiment and / or by mathematical modeling.

[0106] In one embodiment, for one or more measurements of the substrate W, the measurements may be made, at least in part, while the negative pressure is turned off (or at least reduced). Known or predicted knowledge of how the absence of negative pressure affects the shape of the substrate W may be used to compensate for differences in the measurements as a result of the negative pressure being turned off when the measurements are made. There may be a feedforward of substrate shape changes due to changes in negative pressure at the extraction openings 362 of the substrate support 300.

[0107] In one embodiment, the application of negative pressure is stopped when the substrate W is being measured. This reduces undesired heat load when the negative pressure function is not needed (i.e. when the substrate W is being measured rather than exposed). Switching off the negative pressure results in a change in the shape of the substrate W. The change in the shape of the substrate W invalidates (or at least makes less accurate) the values ​​measured when the substrate W is being measured. The measurements may be made, for example, by a precision measurement system (as described above) and / or by a coarse measurement system. The measurements may relate to the height of the surface of the substrate W. The measurements may relate to the alignment of the substrate W in a plane perpendicular to the height direction.

[0108] In one embodiment, the controller 500 is adapted to control at least one measurement system of the lithographic apparatus to measure the substrate W when the application of negative pressure is stopped, in order to obtain measurements of the substrate W. The measurements may be precise measurements of the height of the top surface of the substrate W performed by a substrate mapper, for example as described in relation to step 44 of Figure 6. Additionally or alternatively, the measurements may relate to precise measurements performed by a precision measurement system, such as a fine substrate aligner, as described above in relation to step 45 of Figure 6. Negative pressure will not be applied during these precise measurements of the substrate W.

[0109] In one embodiment, the controller 500 is adapted to apply a correction to the measurements to compensate for the substrate W having a different shape when the application of negative pressure is stopped compared to when negative pressure is applied. The benefits of stopping the application of negative pressure may be obtained without unduly reducing the accuracy of measurements made on the substrate W.

[0110] In an embodiment, a look-up table may be provided to convert measurements of the substrate W made while no negative pressure is applied into measurements that would have been made while negative pressure was applied. Alternatively, a formula or mathematical model may be used instead of a look-up table. In an embodiment, the measurements made on the substrate W are corrected directly, for example by adding a correction component to the measurement. Alternatively, the measurements themselves may not be corrected directly, but the correction may be taken into account in downstream processing in the lithographic apparatus.

[0111] In one embodiment, the controller 500 is adapted to apply corrections to alignment measurements related to the location of the substrate W in a plane perpendicular to the height direction, based on height measurements of the surface of the substrate W. The relationship between the measured heights of the surface of the substrate W at the vertical positions may be known.

[0112] In one embodiment, the effect of applying negative pressure on the shape of the substrate W may be measured. Experiments may be performed to determine how the negative pressure affects the shape of the substrate W. In one embodiment, a correction is applied using the results of the effect measurement. In one embodiment, interpolation and / or extrapolation of the results of the effect measurement is used.

[0113]

[0112] How the shape of the substrate W is affected by the application of negative pressure is expected to be substantially the same for different substrates W of the same type. The mechanical properties of different individual substrates W of the same type are expected to be substantially the same. However, if multiple categories of substrates W with different expected mechanical properties are used, a printing correction may be applied depending on the category of substrate W. For example, if the stiffness of one type of substrate W is expected to be different from the stiffness of another type of substrate W, a different correction may be applied depending on the type of substrate W used. A different set of experiments or a mathematical model may be used to determine the relationship between the shape of the substrate W and the application of negative pressure.

[0114] As explained above, in some embodiments, the negative pressure applied to the opening near the edge of the substrate W is controlled depending on what process is being performed on the substrate W. However, it is not necessary for the opening to be near the edge of the substrate W. In an alternative embodiment, the opening is configured to extract gas from a location close to the center of the substrate W. For example, in one embodiment, the opening is a clamping opening 363 as shown in FIG. 5. The opening may be radially inward of the inner seal 331. The opening may be in the clamping region 353. The opening may be configured to extract gas from the clamping region 353.

[0115] In one embodiment, the clamping state of the substrate W changes during a measurement and exposure cycle. A number of different clamping states correspond to different negative pressures applied to the clamping openings 363. Each clamping state may be defined by the pressure at the clamping openings 363 and, optionally, also by the simultaneous pressure at one or more of the multi-function openings 361, the fluid extraction openings 362, and the peripheral openings 364. A measurement and exposure cycle is a series of steps shown in Figure 6. In one embodiment, the clamping state changes at clamping state change points. A clamping state change point is a time point or period during the measurement and exposure cycle. In one embodiment, there are multiple clamping state change points in a measurement and exposure cycle.

[0116] In an embodiment, the clamp state change points may be associated with periods during which possible delays in the measurement and exposure cycle may be expected. For example, after an exposure has finished, such as after step 50, there may be a variable amount of waiting time before another substrate support 300 loaded with another substrate W is positioned relative to the fluid handling structure IH. During this waiting time, the clamp state may change. For example, the clamp strength may be reduced during the waiting time (i.e., by reducing the magnitude of the negative pressure applied to the clamp openings 363). By reducing the magnitude of the negative pressure, the thermal load may be reduced. As another example, the clamp strength may be increased during the waiting time (i.e., by increasing the magnitude of the negative pressure applied to the clamp openings 363). By increasing the magnitude of the negative pressure, the negative pressure at or near the centre of the substrate support 300 may be controlled to more closely resemble the negative pressure at the edge of the substrate W. This may reduce flow from the centre to the edge, thereby reducing the thermal load. As mentioned above, each clamping state may be defined by the pressure at the clamping openings 363 and optionally also by the simultaneous pressure at one or more of the multi-function openings 361, the fluid extraction openings 362 and the peripheral openings 364. For example, the negative pressure applied to the fluid extraction openings 362 may change (e.g. increase or decrease) during the waiting time before another substrate support 300 loaded with another substrate W is positioned relative to the fluid handling structure IH.

[0117] In an embodiment, the controller 500 is adapted to control the application of an increased negative pressure before starting the application of the negative pressure that will be applied during processing (e.g. measurement) of the substrate W. In an embodiment, the controller 500 is adapted to control the application of an increased negative pressure after stopping the application of the negative pressure that is applied during processing (e.g. measurement) of the substrate W. The increased negative pressure is stronger, i.e. in terms of magnitude, than the negative pressure that is applied during processing (e.g. measurement) of the substrate W. An increased negative pressure may be applied to the clamping openings 363 during a period waiting for another substrate support 300 loaded with another substrate W to be positioned relative to the fluid handling structure IH. The substrate W may be clamped with increased strength during this time.

[0118] Apart from after exposure, there may be other periods in a measurement and exposure cycle where a delay in the cycle may be expected. For example, there may be a waiting period after the measurement of a substrate W has finished. The substrate W may wait at the start position of step 46 (shown in FIG. 6 ) where the substrate W on the substrate support 300 is provided to the exposure system. This waiting period may be expected after step 45 has finished, where the location of the substrate W is precisely determined. The clamping condition may change at this point. The negative pressure applied to the clamp openings 363 may change at this point. For example, the negative pressure applied to the clamp openings 363 may be reduced in the same way as during the waiting period before another substrate support 300 loaded with another substrate W is positioned relative to the fluid handling structure IH.

[0119] A delay may be expected when the substrate W is in the unload position. The substrate W is in the unload position just before step 51, when the substrate W is unloaded from the substrate support 300, for example by the substrate movement system. In an embodiment, the clamping condition is changed just before step 51. In an embodiment, the negative pressure applied to the clamp openings 363 is changed for a period just before the substrate W is unloaded from the substrate support 300. The period during which the clamping strength is changed may end just before the substrate W is unloaded. For example, the negative pressure applied to the clamp openings 363 may be reduced as during a waiting time before another substrate support 300, loaded with another substrate W, is positioned relative to the fluid handling structure IH.

[0120] In one embodiment, a changed (e.g., increased) negative pressure may be applied to the clamp opening 363 during one or more of the expected delay periods during the measurement and exposure cycle. The expected delay periods may be the beginning of step 46 immediately after step 45 is completed, the beginning of step 46 immediately after step 50 is completed, and / or the end of step 46 immediately before step 51 is performed. The magnitudes of the changed (e.g., increased) negative pressures applied during these periods may be the same. Alternatively, different changed negative pressures may be applied during these periods. Changing (e.g., increasing) the negative pressure may improve performance by reducing thermal load. Changing the clamp state at multiple clamp state change points during the measurement and exposure cycle provides increased flexibility.

[0121] In an embodiment, the clamping conditions during exposure may be different compared to the clamping conditions during measurements performed on the substrate W. Alternatively, the same clamping conditions may be used during exposure and measurements.

[0122] In one embodiment, the controller 500 is adapted to start the application of negative pressure used during processing (e.g., measurement) of the substrate W by opening a valve (not shown). In one embodiment, the controller 500 is adapted to stop the application of negative pressure used during processing (e.g., measurement) of the substrate W by closing the valve.

[0123] In one embodiment, the clamp opening 363 is in fluid communication with multiple valves (not shown). In one embodiment, the controller 500 is configured to control the opening and closing of each valve to control the negative pressure applied to the clamp opening 363. In one embodiment, each valve is associated with a negative pressure contribution. The negative pressure contributions of multiple valves may be combined to provide an overall negative pressure applied to the clamp opening 363. In one embodiment, the negative pressure contributions of different valves are different from one another. This allows the controller 500 to control the application of multiple different magnitudes of negative pressure applied to the clamp opening 363.

[0124] For example, if two valves associated with different negative pressure contributions are provided, the controller 500 can selectively switch between four different clamp states. The first clamp state corresponds to both valves being closed. The second clamp state corresponds to the first valve being open and the second valve being closed. The third clamp state corresponds to the first valve being closed and the second valve being open. The fourth clamp state corresponds to both valves being open. In one embodiment, the clamp opening 363 is in fluid communication with three, four, five, or more valves, each associated with a different negative pressure contribution. The valves can be associated with different negative pressure contributions by being connected to different negative pressure sources. If five valves are used, the controller can select between 32 different clamp states, i.e., 32 different negative pressures that can be applied to the clamp opening 363. In one embodiment, one or more of the valves can be configured to connect to multiple different negative pressure sources. This can increase the number of possible different clamp states. In one embodiment, one or more of the valves may be configured to connect to a positive pressure source and / or ambient pressure.

[0125]

[0124] In one embodiment, the controller 500 is configured to control the pressure applied to each of the clamping opening 363, the multi-function opening 361, the fluid extraction opening 362, and the peripheral opening 364.

[0126]

[0125] The burls 341 may have a height (ie the dimension from the surface of the support body 321 to the distal end of the burl) of about 150 μm, although the burls 341 may be of any suitable height.

[0127] The gas supplied through the openings 361, 362, 363, and 364, for example, through the multi-functional opening 361 in the load state and through the peripheral opening 364 in the clamp state, is not particularly limited. For example, clean dry air (CDA), humidified air, or N2 may be supplied. Preferably, humidified air is supplied through the peripheral opening 364, especially in the load state. This is because CDA, which has very low humidity, may cause evaporation of immersion fluid on the outer seal 333, which creates a large thermal load on the outer seal 333. This may cause temporary structural deformation of the substrate support 300, potentially leading to an overlay penalty. Humidified air means that less immersion fluid evaporates from around the outer seal 333, reducing the thermal load.

[0128] The above description references a single opening 361, 362, 363, 364 in each of the gutter regions 351, 352, 354 and the clamping region 353. The openings 361, 362, 363, 364 may extend circumferentially all the way around the substrate support 300. Alternatively, the openings 361, 362, 363, 364 may be circular holes. Preferably, there are multiple discrete hole-shaped openings evenly distributed around each region 351, 352, 353, 354. When there are multiple hole-shaped openings in each region 351, 352, 353, 354, each opening within a region may be configured similarly (i.e., similarly to the openings already defined within a given region). For example, the fluid extraction gutter 352 may have multiple openings, each configured to extract fluid in the same way as the fluid extraction opening 362. However, the additional openings may be configured to operate differently than the already defined openings. For example, fluid extraction gutter 352 may further include an opening configured to supply a fluid. Multi-function opening 361 of multi-function gutter 351 may be configured to supply and / or extract gas. If there are multiple openings in multi-function gutter 351, each may be configured to both extract and supply gas. Alternatively, some openings may be configured only to supply gas, and other openings may be configured only to extract gas.

[0129] The mechanisms for opening and closing these openings 361, 362, 363, 364 are not particularly limited and may utilize any standard valves or the like. Similarly, the systems for supplying gas to and extracting gas from the openings 361, 362, 363, 364 (providing positive and negative pressure) are not particularly limited and may involve any suitable standard components or methods.

[0130]

[0129] The material of the substrate support 300 is not particularly limited and may be any suitable material known in the art. Preferably, the substrate support 300 may be made of silicon carbide (SiSiC).

[0131]

[0130] Manufacturing the substrate support 300 may involve standard techniques known in the art. Some of the openings 361, 362, 363, 364 may be too small for methods such as electrical discharge machining (EDM), in which case laser drilling may be utilized.

[0132] The present invention may provide a lithographic apparatus, which may have any / all of the other features or components of the lithographic apparatus described above. For example, the lithographic apparatus may optionally comprise at least one or more of a radiation source SO, an illumination system IL, a projection system PS, a substrate support WT, etc.

[0133] In particular, the lithographic apparatus may comprise a projection system PS configured to project a radiation beam B towards a region of a surface of a substrate W. The lithographic apparatus may further comprise a substrate support 300 as described in any of the above embodiments and variations.

[0134]

[0133] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it will be appreciated that the lithographic apparatus described herein may have other applications, including the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0135] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, machine-readable media may include read-only memory (ROM), random-access memory (RAM), magnetic storage media, optical storage media, flash memory devices, electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Additionally, firmware, software, routines, and instructions may be described herein as performing particular actions. However, it should be understood that such description is for convenience only, and that such actions actually result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., which, in doing so, may cause actuators or other devices to interact with the physical world.

[0136]

[0135] Although specific reference may be made in this text to embodiments of the invention in the context of lithographic apparatus, embodiments of the invention may also be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatus may be generally referred to as lithography tools.

[0137]

[0136] While particular reference may have been made above to the use of embodiments of the present invention in the context of optical lithography, it will be understood that the present invention is not limited to optical lithography, where the context permits.

[0138]

[0137] While specific embodiments of the present invention have been described above, it will be understood that the invention may be practiced otherwise than as described. The foregoing description is intended to be illustrative and not limiting. Thus, it will be apparent to those skilled in the art that modifications may be made to the invention as described without departing from the scope of the following claims.

Claims

1. a substrate support configured to support a substrate, the substrate support comprising an opening configured to extract a fluid; at least one processing system configured to process the substrate, the processing comprising measuring the substrate or moving the substrate relative to the substrate support; a controller configured to control application of negative pressure to the at least one treatment system and the opening, the controller comprising: commence application of negative pressure to the opening to extract fluid; controlling the processing system to process the substrate; and and stopping the application of the negative pressure so that the processing system at least partially processes the substrate while the negative pressure is applied. an adapted controller; 1. A lithographic apparatus comprising:

2. 2. The lithographic apparatus of claim 1, wherein the opening is configured to extract fluid from a position close to an edge of the substrate, preferably the opening is configured to extract gas from a position close to a center of the substrate or a position radially inward of the opening close to the edge of the substrate relative to the center of the substrate.

3. 3. The lithographic apparatus of claim 2, wherein the controller is adapted to control the application of a changed negative pressure before starting the application of the negative pressure and / or after stopping the application of the negative pressure, optionally the changed negative pressure being stronger than the negative pressure, and wherein the controller is adapted to start the application of the negative pressure by opening a valve and to stop the application of the negative pressure by closing the valve.

4. 4. The lithographic apparatus of claim 1, wherein the at least one processing system comprises a measurement system configured to measure the substrate, and / or the at least one processing system comprises a substrate movement system configured to move the substrate relative to the substrate support, and / or a positioner configured to move the substrate support relative to the at least one processing system.

5. 5. The lithographic apparatus of claim 4, wherein the measurement system is configured to measure a height of a surface of the substrate at a plurality of locations across the substrate, preferably wherein the measurement system is configured to measure a position of the substrate in a plane parallel to the substrate, and / or the substrate movement system is configured to unload the substrate from the substrate support, preferably wherein the substrate movement system is configured to load a substrate onto the substrate support, and / or the controller is adapted to control a positioner to move the substrate support to the processing system before the processing system processes the substrate, and to move the substrate support from the processing system after the processing system has finished processing the substrate.

6. a coarse measurement system configured to measure the substrate more coarsely than the measurement system, and the controller the coarse measurement system stops applying negative pressure to the opening before measuring the substrate; and and adapted to control the coarse measurement system to coarsely measure the substrate when the application of the negative pressure is stopped, and preferably the controller controls the measurement system to: the measurement system begins applying the negative pressure before measuring the substrate; and The measurement system is adapted to stop applying the negative pressure after it has finished measuring the substrate, and preferably the controller is adapted to start applying the negative pressure at least a predetermined time before the measurement system measures the substrate, and preferably the controller is adapted to stop applying the negative pressure a predetermined time after the measurement system has finished measuring the substrate. A lithographic apparatus according to claim 4 or 5 adapted thereto.

7. The controller may further include, for the substrate movement system: the application of the negative pressure begins after the substrate movement system begins a sequence for moving the substrate relative to the substrate support; and the substrate movement system stops applying the negative pressure before completing the sequence for moving the substrate relative to the substrate support. Adapted for use in a lithographic apparatus according to any one of claims 4 to 6.

8. The controller controlling at least one measurement system of the lithographic apparatus to measure the substrate when the application of the negative pressure is stopped to obtain a measurement of the substrate; and applying a correction to the measurements to compensate for the substrate having a different shape when the application of the negative pressure is stopped compared to when the negative pressure is applied. Adapted for use in a lithographic apparatus according to any one of claims 1 to 7.

9. 9. The lithographic apparatus of claim 8, wherein the measurements relate to a height of a surface of the substrate, and wherein the controller is adapted to apply a correction to an alignment measurement relating to a location of the substrate in a plane perpendicular to the height direction based on the measurements.

10. 1. A method for controlling a substrate support of a lithographic apparatus, comprising: supporting a substrate on the substrate support; For each of at least one process performed on the substrate, wherein the process comprises measuring the substrate or moving the substrate relative to the substrate support: commencing application of a negative pressure to the opening in the substrate support to extract fluid; performing the process on the substrate; ceasing the application of the negative pressure such that the processing system at least partially processes the substrate while the negative pressure is applied; and A method for providing the above.

11. 11. The method of claim 10, wherein the fluid is extracted from a location close to an edge of the substrate, and / or the fluid is a gas extracted from a location close to a center of the substrate or a location radially inward of the location close to the edge of the substrate relative to the center of the substrate, and wherein a varied negative pressure is applied before starting to apply the negative pressure and / or after stopping to apply the negative pressure, optionally wherein the varied negative pressure is stronger than the negative pressure, and wherein the at least one process preferably comprises measuring the substrate, and preferably wherein the measuring comprises measuring a height of a surface of the substrate at a plurality of locations across the substrate, and preferably wherein the measuring comprises measuring a position of the substrate in a plane parallel to the substrate.

12. measuring the substrate coarsely relative to said measuring, wherein application of negative pressure to the opening is stopped before the substrate is coarsely measured, and the substrate is coarsely measured when the application of negative pressure is stopped; and / or application of the negative pressure is initiated before the measurements are performed on the substrate; the application of the negative pressure is stopped after the measurement is performed on the substrate, preferably the application of the negative pressure to the opening is started at least a predetermined time before the measurement is performed on the substrate, and preferably the application of the negative pressure is stopped a predetermined time after the processing on the substrate is performed.

12. The method of claim 10 or 11.

13. The at least one process comprises moving the substrate relative to the substrate support, preferably said moving the substrate comprises unloading the substrate from the substrate support, preferably said moving the substrate comprises loading a substrate onto the substrate support, preferably the application of the negative pressure is initiated after a sequence for moving the substrate relative to the substrate support; The method of claim 10 , wherein the application of the negative pressure is stopped before the sequence for moving the substrate relative to the substrate support is completed.

14. and / or transferring the substrate support to at least one processing system configured to perform a respective at least one process on the substrate, preferably transferring the substrate support to the processing system before the processing system performs the process on the substrate, and transferring the substrate support from the processing system after the processing system has performed the process on the substrate; controlling at least one measurement system of the lithographic apparatus to measure the substrate when the application of the negative pressure is stopped to obtain a measurement of the substrate; and applying a correction to the measurements to compensate for the substrate having a different shape when the application of the negative pressure is stopped compared to when the negative pressure is applied, preferably comprising:

14. The method of claim 10, further comprising measuring the effect of applying the negative pressure on the shape of the substrate, preferably wherein the correction is applied using results of the measurement of the effect, preferably wherein the correction is applied using a model for predicting the effect of applying the negative pressure on the shape of the substrate, preferably wherein the correction is applied using results of the measurement of the effect, preferably wherein the correction is applied using a model for predicting the effect of applying the negative pressure on the shape of the substrate.

15. A method for manufacturing a device, comprising a method for controlling a substrate support according to any one of claims 10 to 14.

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