System for use in a lithographic apparatus

Abstract

A system for use in a lithographic apparatus comprises a substrate table, another device, and at least one deformable partition. The substrate table (e.g. a wafer stage) is arranged to support a substrate. The system is configurable in a first configuration such that a surface of the device faces and is adjacent to the substrate and the substrate table. The at least one deformable partition (a) extends partially from the substrate table towards the surface of the device when the system is in the first configuration, or (b) extends partially from a surface of the device facing and adjacent to the substrate and substrate table towards the substrate table when the system is in the first configuration.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to European Application No. 22151287.4 filed on January 13, 2022 and European Application No. 22187859.8 filed on July 29, 2022, which are incorporated by reference in their entireties herein.

[0002]

[0002] The present invention relates to a system for use in a lithographic apparatus. In general, the system may comprise a substrate table (e.g. a wafer stage) for use in the lithographic apparatus. The lithographic apparatus may be an extreme ultraviolet (EUV) lithographic apparatus. The system may further comprise another device that is positioned adjacent and opposite the substrate table in use. [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 from a patterning device (e.g. mask) onto a layer of radiation-sensitive material (resist) provided on the substrate.

[0004]

[0004] To project a pattern onto a substrate, a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Lithographic apparatus using extreme ultraviolet (EUV) radiation having a wavelength in the range of 4-20 nm, e.g. 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than lithographic apparatus using radiation having a wavelength of, e.g., 193 nm.

[0005] It would be desirable to at least partially address one or more problems associated with known lithographic apparatus, whether or not identified herein. Summary of the Invention

[0006]

[0006] According to a first aspect of the present disclosure, there is provided a system comprising: a substrate table arranged to support a substrate; a device, the device being configurable in a first configuration such that a surface of the device faces and is adjacent to the substrate and substrate table; and at least one deformable partition, (a) extending partially from the substrate table towards the surface of the device when the system is in the first configuration, or (b) extending partially from a surface of the device facing and adjacent to the substrate and substrate table towards the substrate table when the system is in the first configuration.

[0007] The system according to the first aspect may form part of a lithographic apparatus.

[0008]

[0008] The device may comprise a projection system configured to project a patterned radiation beam onto a substrate supported by the substrate table. The device may further comprise a heat shield. Such a projection system and heat shield may define a surface facing the substrate table while the projection system projects the patterned radiation beam onto the substrate supported by the substrate table.

[0009]

[0009] Alternatively, the device may comprise part of a lithographic apparatus used to perform measurements of a substrate (e.g. a resist-coated silicon wafer) supported by a substrate table (e.g. a wafer stage) prior to exposure of the substrate to patterned radiation.

[0010]

[0010] The system is configurable in a first configuration such that a surface of the device faces and is adjacent to the substrate and substrate table. The configuration of the system may be changed by moving the substrate table relative to the device. In some embodiments, the system may form part of a lithographic apparatus, in which the substrate table is positionable at at least (a) an exposure location (e.g. proximate to a projection system) and (b) a measurement location (e.g. proximate to one or more measurement systems). In such a lithographic apparatus, the system may be considered to be in the first configuration when the substrate table is at the exposure location and in the second configuration when the substrate table is at the measurement location (or vice versa).

[0011]

[0011] The system according to the first aspect is advantageous as follows.

[0012]

[0012] In use, the substrate table (e.g. a wafer stage of a lithographic apparatus) may be positioned such that at least a portion of the substrate faces a substantially parallel surface (of the device). For example, the substrate table is positioned such that a portion of the substrate receives patterned radiation from a projection system while the projection system projects a patterned radiation beam onto a substrate supported by the substrate table. The remaining portion of the substrate faces the substantially parallel surface, which may for example comprise a heat shield.

[0013]

[0013] As discussed further below, it may be beneficial to reduce the gap between some parts of the substrate and the surrounding apparatus (e.g. to reduce the amount of particles and / or radiation passing to or from particular parts of the substrate). To this end, it would be beneficial to reduce the distance between the substrate table (or substrate) and the facing surface. However, since it is undesirable for the substrate or substrate table to contact the facing surface, there is a limit to the minimum distance that can be achieved. Furthermore, some tolerance may be allowed to prevent such contact in the event of an earthquake or the like, thereby preventing damage to the substrate, substrate table or facing surface.

[0014]

[0014] Advantageously, the at least one deformable partition of the system according to the first aspect further reduces the gap between some parts of the substrate and the surrounding equipment. The at least one deformable partition extends partially from a first member (at its proximal end) towards a second member (at its distal end). The first and second members are (a) the substrate table or (b) a surface of the device facing the substrate table. When the first and second members move towards each other (e.g. in case of an earthquake), the second member may contact the distal end of the deformable partition and deform it. Since the at least one partition is deformable, advantageously such contact will not result in damage to either the substrate or the surface facing it in use (e.g. a heat shield). Thus, advantageously, the system according to the first aspect allows the physical gap between the substrate table (or substrate) and an adjacent surface to be reduced while limiting the risk of damage.

[0015]

[0015] In general, the at least one deformable partition may extend from a member on which an object that is desired to be protected is disposed. For example, for an embodiment in which the at least one deformable partition is desired to protect a substrate, the at least one deformable partition may extend from the substrate table. Similarly, for an embodiment in which the at least one deformable partition is desired to protect a substrate and something disposed in a device opposite and adjacent to the substrate table, the at least one deformable partition may extend from the device.

[0016]

[0016] The device may comprise a projection system configured to project a patterned beam of radiation through an aperture onto a substrate supported by a substrate table.

[0017]

[0017] Such a projection system may be opposed to a substrate table while the projection system projects a patterned radiation beam onto a substrate supported by the substrate table.

[0018] The device may further comprise one or more components extending from the opening and at least partially defining a surface of the device facing and adjacent the substrate and substrate table when the system is in the first configuration.

[0019] The aforementioned components may comprise any or all of the following: a body or housing of the projection system having an aperture defined therein, a heat shield, a mirror used as part of the interferometric measurement system, and / or a spoiler configured to direct part of the gas flow away from such a mirror.

[0020] At least one deformable partition may extend partially from the substrate table towards a surface of the substrate and device opposite and adjacent to the substrate table when the system is in the first configuration.

[0021]

[0021] The surface facing the substrate table may be provided with a heat shield or may be at least partly formed by a heat shield.

[0022]

[0022] Advantageously, a deformable partition extending partly from the substrate table to a surface facing the substrate table (e.g. during lithographic exposure of the substrate) provides a barrier between the part of the substrate table supporting the substrate and a peripheral part of the substrate table and the ambient environment. As the deformable partition extends from the substrate table, it remains in a fixed position relative to the substrate supported by the substrate table.

[0023]

[0023] In a lithographic apparatus, it is desirable to reduce the number of particles incident on the substrate in order to reduce the occurrence of wafer defects. A deformable partition, extending partially from the substrate table towards a surface facing the substrate table during use (e.g. during lithographic exposure of the substrate), acts to further reduce the ingress of particles from the surrounding environment into the area in which the substrate is disposed.

[0024]

[0024] It will be appreciated that at least one deformable partition which extends partially from the substrate table towards a surface facing the substrate table in use (e.g. while the projection system is projecting a patterned radiation beam onto a substrate supported by the substrate table) has a range component at least in a direction perpendicular to the plane of the substrate.

[0025] In principle, the at least one deformable partition, which extends partly from the substrate table towards the surface facing the substrate table, may extend substantially all around the periphery (or perimeter) of the area for supporting the substrate. This would maximize the separation between the part of the substrate table supporting the substrate and the peripheral part of the substrate table and the surrounding environment.

[0026]

[0026] At least one deformable partition that extends partially from the substrate table toward the surface of the substrate and adjacent device facing the substrate table when the system is in the first configuration may extend only partially around the periphery of an area of ​​the substrate table for supporting the substrate.

[0027]

[0027] For example, in some embodiments, at least one deformable partition extending partially from the substrate table toward a surface facing the substrate table in use extends along two opposing surfaces of a generally rectangular area of ​​the substrate table for supporting a substrate.

[0028] Advantageously, such an arrangement allows a line of sight of a laser beam to pass from the surrounding environment to a part of the substrate table adjacent the part of the substrate table that supports the substrate. Such a laser beam may be used, for example, as part of an interferometric measurement system for measuring the position (e.g. height) of the substrate table relative to a reference frame.

[0029]

[0029] The lithographic apparatus may further comprise a scanning mechanism configured to control the relative position of the substrate table and the device.

[0030]

[0030] For example, the lithographic apparatus may be a lithographic scanner. The projection system may be operable to project the patterned radiation beam onto an exposure area or exposure slit. The exposure area may be an elongated (either linear or curved) area in an image plane. The scanning mechanism may be configured to position the substrate table such that a substrate supported by the substrate table is generally located within the image plane. The scanning mechanism may be further configured to move the substrate table to scan a target area of ​​the substrate through the exposure area.

[0031]

[0031] At least one deformable partition may extend partially towards the substrate table from a surface of the device facing and adjacent the substrate and substrate table when the system is in the first configuration.

[0032] Advantageously, a deformable partition, extending partly from a surface facing the substrate table towards the substrate table (e.g. during exposure of the substrate), can provide a barrier between the exposure area (also known as a slit) and surrounding parts of the apparatus or system. Because the deformable partition extends from a surface facing the substrate table in use, it remains in a fixed position relative to the device (e.g. the projection system and any other apparatus connected to it).

[0033] As will be described further below, it may be desirable to (a) reduce the number of particles leaving the volume adjacent the exposure area into the surrounding environment, and / or (b) reduce the amount of radiation from the projection system that is incident on the substrate outside the exposure area. A deformable partition, extending partially from a surface of the device that faces the substrate table during use (e.g. during exposure of the substrate) towards the substrate table, can achieve this.

[0034]

[0034] It will be appreciated that at least one deformable partition which extends partially from a surface facing the substrate table when in use towards the substrate table (e.g. while the projection system is projecting a patterned radiation beam onto a substrate supported by the substrate table) has a range component at least in a direction perpendicular to the plane of the substrate.

[0035]

[0035] The at least one deformable partition that extends partially from a surface facing the substrate table towards the substrate table may extend substantially all around a periphery of the exposure region. Alternatively, the at least one deformable partition that extends partially from a surface facing the substrate table towards the substrate table may extend only partially around a periphery of the exposure region.

[0036]

[0036] At least one deformable partition facing the substrate and substrate table when the system is in a first configuration towards the substrate table and extending partially from the surface of the adjacent device may comprise at least one deformable partition extending from the projection system in the vicinity of the exposure area.

[0037]

[0037] At least one deformable partition extending from the projection system near the exposure area may extend generally along a non-scanning direction.

[0038]

[0038] At least one deformable partition facing the substrate and substrate table when the system is in a first configuration towards the substrate table and extending partially from a surface of an adjacent device may comprise at least one deformable partition extending from a surface adjacent a mirror used as part of the interferometric measurement system.

[0039]

[0039] At least one deformable partition extending from a surface adjacent to a mirror used as part of an interferometric measurement system may extend generally along the scan direction.

[0040]

[0040] At least one of the at least one deformable partitions may be elastically deformable.

[0041]

[0041] Advantageously, such an elastically deformable partition can be deformed from a nominal position when its distal end comes into contact with another object (e.g. during an earthquake) and can return to the nominal position when the object causing the deformation is removed.

[0042]

[0042] The aforementioned elastically deformable partition may have a range component at least in a direction parallel to the plane of the substrate.

[0043]

[0043] That is, rather than simply extending perpendicular to the plane of the substrate, the elastically deformable partitions may extend at an oblique angle to the plane of the substrate, and such elastically deformable partitions may bend laterally upon application of a force from an object generally perpendicular to the plane of the substrate.

[0044]

[0044] The aforementioned elastically deformable partition may be elastically deformable in a direction generally perpendicular to the plane of the substrate.

[0045]

[0045] For example, in a direction perpendicular to the plane of the substrate, the elastically deformable partition may be generally in the form of a spring, such that upon application of a force from an object generally perpendicular to the plane of the substrate, such elastically deformable partition may compress in that direction.

[0046]

[0046] At least one of the at least one deformable partitions may include a frangible portion between its proximal and distal ends.

[0047]

[0047] Advantageously, such frangible portions enable the deformable partition to break when its distal end contacts another object (e.g. during an earthquake). Such a deformable partition may be described as permanently deformable.

[0048] According to a second aspect of the present disclosure, there is provided a substrate table for use in a system of the first aspect of the present disclosure.

[0049] According to a third aspect of the present disclosure, there is provided a device for use in the system of the first aspect of the present disclosure.

[0050]

[0050] According to a fourth aspect of the present invention, there is provided a substrate table arranged to support a substrate, the substrate table comprising at least one deformable partition extending from the substrate table and having a component of extent at least in a direction perpendicular to the plane of the substrate when supported by the substrate table.

[0051] A substrate table according to the fourth aspect may form part of a system according to the first aspect.

[0052]

[0052] In use, the substrate table may be positionable relative to another device such that a surface of the device faces and is adjacent to the substrate and the substrate table. When in such a configuration, the at least one deformable partition may extend partially from the substrate table towards the surface of the device.

[0053]

[0053] Advantageously, at least one deformable partition of the substrate table according to the fourth aspect can further reduce the gap between the substrate and the surrounding apparatus. When the substrate table moves towards another device adjacent to the substrate table in use (e.g. in case of an earthquake), the other device may contact the distal end of the deformable partition and deform it. Since the at least one partition is deformable, advantageously such contact will not result in damage to either the substrate or the surface facing it in use (e.g. a heat shield). Thus, advantageously, the substrate table according to the fourth aspect allows the physical gap between the substrate table (or substrate) and adjacent surfaces to be reduced, while limiting the risk of damage.

[0054]

[0054] Advantageously, the one or more deformable partitions may provide a barrier between the part of the substrate table supporting the substrate and a peripheral part of the substrate table and the ambient environment. The deformable partitions extend from the substrate table and therefore remain in a fixed position relative to the substrate supported by the substrate table.

[0055]

[0055] In a lithographic apparatus, it is desirable to reduce the number of particles incident on the substrate in order to reduce the occurrence of wafer defects. A deformable partition, extending partially from the substrate table towards a surface facing the substrate table during use (e.g. during lithographic exposure of the substrate), acts to further reduce the ingress of particles from the surrounding environment into the area in which the substrate is disposed.

[0056]

[0056] In principle, the at least one deformable partition may extend substantially all around the periphery (or perimeter) of the area for supporting the substrate. This would maximise the separation between the part of the substrate table supporting the substrate and the peripheral part of the substrate table and the surrounding environment.

[0057]

[0057] At least one deformable partition extending from the substrate table may extend only partially around a periphery of an area of ​​the substrate table for supporting the substrate.

[0058]

[0058] For example, in some embodiments, at least one deformable partition extending from the substrate table may extend along two opposing surfaces of a generally rectangular area of ​​the substrate table for supporting a substrate.

[0059] Advantageously, such an arrangement allows a line of sight of a laser beam to pass from the surrounding environment to a part of the substrate table adjacent the part of the substrate table that supports the substrate. Such a laser beam may be used, for example, as part of an interferometric measurement system for measuring the position (e.g. height) of the substrate table relative to a reference frame.

[0060]

[0060] At least one of the at least one deformable partitions may be elastically deformable.

[0061]

[0061] Advantageously, such an elastically deformable partition can be deformed from a nominal position when its distal end comes into contact with another object (e.g. during an earthquake) and can return to the nominal position when the object causing the deformation is removed.

[0062]

[0062] The aforementioned elastically deformable partition may have a component of extent at least in a direction parallel to the plane of the substrate when supported by the substrate table.

[0063]

[0063] That is, rather than simply extending perpendicular to the plane of the substrate, the elastically deformable partitions may extend at an oblique angle to the plane of the substrate, and such elastically deformable partitions may bend laterally upon application of a force from an object generally perpendicular to the plane of the substrate.

[0064]

[0064] The aforementioned elastically deformable partition may be elastically deformable in a direction generally perpendicular to the plane of the substrate when supported by the substrate table.

[0065]

[0065] For example, in a direction perpendicular to the plane of the substrate, the elastically deformable partition may be generally in the form of a spring, such that upon application of a force from an object generally perpendicular to the plane of the substrate, such elastically deformable partition may compress in that direction.

[0066]

[0066] At least one of the at least one deformable partitions may include a frangible portion between its proximal and distal ends.

[0067]

[0067] Advantageously, such frangible portions enable the deformable partition to break when its distal end contacts another object (e.g. during an earthquake). Such a deformable partition may be described as permanently deformable.

[0068]

[0068] The inventors have found that to maximize protection of the substrate during exposure, the following methods are most effective: (a) increasing the pressure between the substrate and an adjacent body (e.g., a heat shield), (b) increasing the gas velocity between the substrate and an adjacent body (e.g., a heat shield), and (c) decreasing the gap between the substrate and an adjacent body (e.g., a heat shield). This insight is exploited by the fifth aspect of the present disclosure and the sixth aspect of the present disclosure, as described below.

[0069]

[0069] According to a fifth aspect of the present disclosure, there is provided a substrate table configured to support a substrate comprising a body, a clamp provided on a surface of the body, the clamp operable to support the substrate and to clamp the substrate to the clamp, a partition extending from the surface substantially around an outer periphery of the clamp, and at least one gas outlet provided in a portion of the surface that is within the partition.

[0070]

[0070] The substrate table according to the fifth aspect of the present disclosure is advantageous as follows.

[0071]

[0071] In use, the substrate table may be positionable relative to another device such that a surface of the device faces and is adjacent to the substrate and substrate table. When in such a configuration, at least one partition may extend partially from the substrate table towards the surface of the device to create a mini-environment between the part of the substrate table inside the partition and the other device.

[0072]

[0072] A substrate table according to the fifth aspect of the present disclosure may, in use, form part of a lithographic apparatus. The substrate table may alternatively be referred to as a wafer stage or a wafer chuck.

[0073] In use, the substrate table (e.g. a wafer stage of a lithographic apparatus) may be positioned such that at least a portion of the substrate faces a substantially parallel surface (of the device). For example, the substrate table is positioned such that a portion of the substrate receives patterned radiation from a projection system while the projection system projects a patterned radiation beam onto a substrate supported by the substrate table. The remaining portion of the substrate faces the substantially parallel surface, which may for example comprise a heat shield.

[0074]

[0074] In general, it is desirable to reduce the amount of particles passing through and impinging on the substrate, for example particles impinging on the substrate can result in yield loss in the lithographic apparatus.

[0075]

[0075] Advantageously, the partition extending from the surface substantially around the circumference of the clamp defines a mini-environment within the partition in the vicinity of the substrate (e.g. when another object or device is adjacent to the substrate table parallel to the substrate). At least one gas outlet is provided in the part of the surface that is within the partition, which allows gas to be provided to the mini-environment. Advantageously, in use, a gas flow is provided in the vicinity of the substrate table from the at least one gas outlet to move particles away from the substrate and to reduce particle incidence on the substrate supported by the substrate table. The partition allows the pressure within the mini-environment to be increased for a given gas flow into the mini-environment. In addition, the partition, and the mini-environment defined thereby, may allow the gap between the substrate and an adjacent object (e.g. a heat shield) to be increased without increasing the risk of particle incidence on the substrate.

[0076] As explained above, with the substrate table according to the fifth aspect of the present disclosure the same pressure can be reached with less gas flow in the vicinity of the substrate and in a larger volume due to the increased gap between the substrate and adjacent objects (e.g. heat shields). Advantageously, this results in a more uniform pressure, reducing the amount of localized pressure peaks and lowering the risk of titanium embrittlement.

[0077]

[0077] In particular, the combination of a partition extending from the surface substantially around the circumference of the clamp and at least one gas outlet provided in a portion of the surface that is within the partition allows the pressure in the mini-environment defined by the partition to be increased (to protect the substrate), while the remainder of the compartment in which the substrate table is arranged can remain at a relatively low pressure. This is beneficial for several reasons. Firstly, it reduces the risk of Paschen discharge of high voltage components in the vicinity of the substrate table, e.g. in the compartment in which the substrate table is arranged (which may be referred to as the wafer stage compartment). Secondly, lower pressure in the bulk of the wafer stage compartment means smaller pressure fluctuations when the substrate table is moving, resulting in less disturbance to (interferometric) wafer stage positioning measurements. Thirdly, there is no need to inject excess hydrogen gas to maintain high pressure throughout the substrate table compartment. This reduces the amount of (hydrogen) gas required, making the apparatus more energy efficient, less expensive (due to reduced hydrogen) and less demanding on pumping power.

[0078] Another advantage of the mini-environment created by the partition is that a given pressure level can be achieved in the vicinity of the substrate with a significantly lower flow rate injection of (hydrogen) gas, which in turn results in less disturbance to the functionality of the clamp from this gas flow. For example, this can help the thermal regulation of the clamp and the body and the relaxation functionality of the clamp.

[0079]

[0079] Another advantage of the substrate table according to the fifth aspect of the present disclosure is that radiative heat transfer to the substrate is reduced, which makes thermal management of the substrate easier.

[0080] Another advantage of the substrate table according to the fifth aspect of the present disclosure is that the partition also acts as a particle shield, for example the partition can act as a physical barrier that can reflect particles generated at such high velocities that they are not blocked by the gas flow in the substrate table compartment, keeping such particles away from the wafer.

[0081]

[0081] At least one gap may be provided between the partition and the surface from which it extends.

[0082]

[0082] Such an arrangement allows the gas flow to leave the mini-environment toward the bottom of the mini-environment (i.e., adjacent to the surface of the body), which is advantageous because it encourages the gas flow to be directed downward toward the body, providing additional protection for the substrate.

[0083]

[0083] The partition may include one or more walls and a plurality of spaced apart legs, burls, or protrusions extending from a surface of the body to the one or more walls.

[0084]

[0084] Advantageously, the spaces between the legs, burls or protrusions provide one or more gaps between the partition and the surface from which the partition extends.

[0085]

[0085] It will be appreciated that a partition extending from a surface of the body will have a range component at least in a direction perpendicular to the plane of the substrate.

[0086]

[0086] The partition extending from the surface of the body may extend in a direction perpendicular to the plane of the substrate.

[0087]

[0087] The height of the partition from the surface of the body in a direction perpendicular to the plane of the substrate may be less than the height of the substrate supported by the clamp in a direction perpendicular to the plane of the substrate.

[0088]

[0088] That is, in use, the distal (or upper) surface of the substrate is higher than the partition. In such an arrangement, if an object adjacent to the substrate table (e.g. a heat shield) in use moves towards the substrate table (e.g. in the case of an earthquake), it may contact the substrate rather than the partition. Advantageously, such contact will not result in damage to the partition or to the other object (e.g. a heat shield) facing it in use.

[0089]

[0089] The gas provided from the at least one gas outlet may be referred to as backfill gas.

[0090]

[0090] A backfill gas may be provided in the space between the body and the clamp (eg, between the support burls). A backfill gas may be provided in the space between the clamp and the substrate (eg, between the support burls).

[0091]

[0091] At least one of the at least one gas outlets may be provided near the clamp. For example, at least one of the at least one gas outlets may be provided between the body and the clamp. Additionally or alternatively, at least one of the at least one gas outlets may be provided between the partition and the clamp, adjacent to the clamp.

[0092]

[0092] The at least one gas outlet may be arranged to direct gas flow to a ring around the clamp, whereby gas flow is directed away from the clamp.

[0093]

[0093] Such an arrangement may be referred to as a backfill gas flow shield. In use, a flow of gas (e.g., hydrogen gas) may be injected into a ring around the substrate (wafer), causing the gas flow to be directed away from the substrate, thus moving particles away from the substrate. This gas flow thus forms a shield around the clamp and the substrate.

[0094]

[0094] The substrate table may further comprise a gas supply operable to supply gas to the at least one gas outlet.

[0095]

[0095] According to a sixth aspect of the present disclosure, there is provided a system comprising a substrate table according to the fifth aspect of the present disclosure and a device, the system being configurable in a first configuration such that a surface of the device faces and is adjacent to the substrate table and a substrate supported thereby.

[0096]

[0096] The device may comprise a projection system configured to project a patterned radiation beam onto a substrate supported by the substrate table. The device may further comprise a heat shield. Such a projection system and heat shield may define a surface facing the substrate table while the projection system projects the patterned radiation beam onto the substrate supported by the substrate table.

[0097]

[0097] Alternatively, the device may comprise part of a lithographic apparatus used to perform measurements of a substrate (e.g. a resist-coated silicon wafer) supported by a substrate table (e.g. a wafer stage) prior to exposure of the substrate to patterned radiation.

[0098]

[0098] The system can be configured in a first configuration such that a surface of the device faces and is adjacent to the substrate and substrate table. The configuration of the system can be changed by moving the substrate table relative to the device. In some embodiments, the system may form part of a lithographic apparatus, in which the substrate table is positionable at at least (a) an exposure location (e.g. proximate to a projection system) and (b) a measurement location (e.g. proximate to one or more measurement systems). In such a lithographic apparatus, the system can be considered to be in the first configuration when the substrate table is at the exposure location and in the second configuration when the substrate table is at the measurement location (or vice versa).

[0099]

[0099] The device may comprise a projection system configured to project a patterned beam of radiation through an aperture onto a substrate supported by a substrate table.

[0100] [000100] Such a projection system may be opposed to a substrate table while the projection system projects a patterned radiation beam onto a substrate supported by the substrate table.

[0101] [000101] The device may further comprise one or more components extending from the opening and at least partially defining a surface of the device facing and adjacent the substrate table when the system is in the first configuration.

[0102] [000102] The aforementioned components may include any or all of the following: a body or housing of the projection system having an aperture defined therein, a heat shield, a mirror used as part of the interferometric measurement system, and / or a spoiler configured to direct part of the gas flow away from such a mirror.

[0103] [000103] The system may further comprise a scanning mechanism configured to control the relative position of the substrate table and the device.

[0104] [000104] For example, the lithographic apparatus may be a lithographic scanner. The projection system may be operable to project the patterned radiation beam onto an exposure area or exposure slit. The exposure area may be an elongated (either linear or curved) area in an image plane. The scanning mechanism may be configured to position the substrate table such that a substrate supported by the substrate table is generally located in the image plane. The scanning mechanism may be further configured to move the substrate table to scan a target area of ​​the substrate through the exposure area.

[0105] [000105] According to a sixth aspect of the present disclosure, there is provided a lithographic apparatus comprising a system according to the first aspect of the present disclosure, a substrate table according to the fourth aspect of the present disclosure, a substrate table according to the fifth aspect of the present disclosure, or a system according to the sixth aspect of the present disclosure. [Brief description of the drawings]

[0106] [000106] 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, in which:

[0107] [Figure 1] 1 depicts a lithography system comprising a lithographic apparatus and a radiation source. [Figure 2A] FIG. 1 shows a schematic cross-section of a part of the lithographic apparatus in the vicinity of the substrate table (and substrate), including part of the projection system, in a plane containing the scanning direction (y-direction) of the lithographic apparatus. [Figure 2B] Part of the lithographic apparatus shown in Figure 1 near the substrate table (and substrate), including part of the projection system, is shown diagrammatically in cross-section in a plane containing the non-scanning direction (x-direction) of the lithographic apparatus. [Diagram 3] 1 shows a fragment of a substrate table (which supports a substrate) and a generally parallel barrier facing and adjacent the substrate table and substrate. [Figure 4] 4 shows the same substrate table, substrate and barrier fragment as shown in FIG. 3, plus a deformable partition extending part way from the substrate table towards the surface of the barrier. [Figure 5A] 5 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 4 extending partially from the substrate table towards a facing surface; [Figure 5B] 5 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 4 extending partially from the substrate table towards a facing surface; [Figure 6A]5 shows a second exemplary embodiment of a deformable partition of the type shown in FIG. 4 extending partially from the substrate table towards a facing surface; [Figure 6B] 5 shows a second exemplary embodiment of a deformable partition of the type shown in FIG. 4 extending partially from the substrate table towards a facing surface; [Figure 7A] 5 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 4 extending partially from the substrate table towards a facing surface; [Figure 7B] 5 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 4 extending partially from the substrate table towards a facing surface; [Figure 8] 1 shows a fragment of a substrate table (which supports a substrate) and part of a generally parallel barrier facing and adjacent the substrate table and substrate. [Figure 9] 9 shows the same substrate table, substrate and barrier fragment as shown in FIG. 8, plus a deformable partition extending part way from the surface towards the substrate table. [Figure 10A] FIG. 10 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 9 adjacent to a mirror used as part of an interferometric measurement system, extending partially from the surface towards the substrate table. [Figure 10B] FIG. 10 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 9 adjacent to a mirror used as part of an interferometric measurement system, extending partially from the surface towards the substrate table. [Figure 11A] 10 shows a second exemplary embodiment of a deformable partition of the type shown in FIG. 9 adjacent to a mirror used as part of an interferometric measurement system, extending partially from the surface towards the substrate table. [Figure 11B] 10 shows a second exemplary embodiment of a deformable partition of the type shown in FIG. 9 adjacent to a mirror used as part of an interferometric measurement system, extending partially from the surface towards the substrate table. [Figure 12A] 10 shows a third exemplary embodiment of a deformable partition of the type shown in FIG. 9 adjacent to a mirror used as part of an interferometric measurement system, extending partially from the surface towards the substrate table. [Figure 12B] 10 shows a third exemplary embodiment of a deformable partition of the type shown in FIG. 9 adjacent to a mirror used as part of an interferometric measurement system, extending partially from the surface towards the substrate table. [Figure 13] 1 shows a fragment of a substrate table (which supports a substrate) and part of a generally parallel barrier facing and adjacent the substrate table and substrate. [Figure 14] 9 shows the same cross-section of the substrate table, substrate and barrier as shown in FIG. 8, but in addition shows two deformable partitions, each extending part way from the housing of the projection system towards the substrate table. [Figure 15A] 15 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 14 extending partially from the projection system towards the substrate table in the vicinity of the exposure area. [Figure 15B] 15 shows a first exemplary embodiment of a deformable partition of the type shown in FIG. 14 extending partially from the projection system towards the substrate table in the vicinity of the exposure area. [Figure 16A] 15 shows a second exemplary embodiment of a deformable partition of the type shown in FIG. 14 extending partially from the projection system towards the substrate table in the vicinity of the exposure area. [Figure 16B] 15 shows a second exemplary embodiment of a deformable partition of the type shown in FIG. 14 extending partially from the projection system towards the substrate table in the vicinity of the exposure area. [Figure 17A] 15 shows a third exemplary embodiment of a deformable partition of the type shown in FIG. 14, extending partially from the projection system towards the substrate table in the vicinity of the exposure area. [Figure 17B]15 shows a third exemplary embodiment of a deformable partition of the type shown in FIG. 14, extending partially from the projection system towards the substrate table in the vicinity of the exposure area. [Figure 18A] 1 depicts a cross-sectional view, not to scale, of a substrate table according to an embodiment of the present disclosure in an arrangement such that a substrate supported by the substrate table is adjacent to and facing a device, such as a heat shield; [Figure 18B] FIG. 18B shows a plan view of the substrate table shown in FIG. 18A; [Figure 19A] The body and the clamps of the substrate table shown in Figures 18A and 18B and the substrate are shown in more realistic dimensions. [Figure 19B] The partition of the substrate table and the substrate shown in Figures 18A and 18B are shown in more realistic scale. [Figure 19C] The device shown in FIG. 19A is shown together with the partition shown in FIG. 19B. [Figure 20] FIG. 19D shows an enlarged side view of the partition and main body shown in FIG. 19C. [Figure 21] A simulation of the pressure increase achieved in the vicinity of the substrate due to the presence of a partition of the substrate table shown in Figures 19A to 20 is shown as a function of the height of the partition relative to the height of the substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0108] [000107] Figure 1 shows a lithography system comprising a radiation source SO and a lithographic apparatus LA. The source SO is configured to generate a beam of EUV radiation B and to provide this beam of EUV radiation B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g. a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

[0109] [000108] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. To that end, the illumination system IL may comprise a facetted field mirror device 10 and a facetted pupil mirror device 11. Together the facetted field mirror device 10 and the facetted pupil mirror device 11 impart a desired cross-sectional shape and a desired intensity distribution to the EUV radiation beam B. The illumination system IL may comprise other mirrors or devices in addition to or instead of the facetted field mirror device 10 and the facetted pupil mirror device 11.

[0110] [000109] After being so conditioned, the EUV radiation beam B interacts with the patterning device MA. This interaction results in a patterned EUV radiation beam B'. The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. To this end, the projection system PS may comprise a number of mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held by a substrate table WT. The projection system PS may apply a demagnification factor to the patterned EUV radiation beam B' to form images of features that are smaller than corresponding features on the patterning device MA. For example, a demagnification factor of 4 or 8 may be applied. Although the projection system PS is shown in Figure 1 as having only two mirrors 13, 14, the projection system PS may comprise a different number of mirrors (for example 6 or 8 mirrors).

[0111] [000110] The substrate W may include a preformed pattern. In such a case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the preformed pattern on the substrate W.

[0112] [000111] A relative vacuum, ie a small amount of gas (eg hydrogen) at a pressure significantly below atmospheric pressure, may be provided in the source SO, illumination system IL and / or projection system PS.

[0113] [000112] The radiation source SO shown in Figure 1 is, for example, of a type sometimes referred to as a laser-produced plasma (LPP) radiation source. A laser system 1, which may for example include a CO2 laser, is arranged to deposit energy via a laser beam 2 into a fuel, for example tin (Sn), provided by a fuel emitter 3. Although the following description refers to tin, any suitable fuel may be used. The fuel may for example be in liquid form or may for example be a metal or alloy. The fuel emitter 3 may comprise a nozzle configured to direct the tin, for example in the form of droplets, along a trajectory towards a plasma formation region 4. The laser beam 2 is incident on the tin in the plasma formation region 4. The deposition of the laser energy on the tin creates a tin plasma 7 in the plasma formation region 4. During de-excitation and recombination of electrons with the plasma ions, radiation including EUV radiation is emitted from the plasma 7.

[0114] [000113] EUV radiation from the plasma is collected and focused by a collector 5. Collector 5 may include, for example, a near normal incidence radiation collector 5 (sometimes more commonly referred to as a normal incidence radiation collector). Collector 5 may have a multi-layer mirror structure arranged to reflect EUV radiation (e.g., EUV radiation having a desired wavelength, such as 13.5 nm). Collector 5 may have an elliptical configuration with two foci. A first of the foci may be at the plasma formation region 4 and a second of the foci may be at an intermediate focus 6, which is discussed below.

[0115] [000114] The laser system 1 may be spatially separated from the radiation source SO. If this is the case, the laser beam 2 may be passed from the laser system 1 to the radiation source SO by a beam delivery system (not shown) comprising, for example, suitable directing mirrors and / or beam expanders and / or other optics. The laser system 1, the radiation source SO and the beam delivery system together may be considered as a radiation system.

[0116] [000115] The radiation reflected by the collector 5 forms an EUV radiation beam B. The EUV radiation beam B is focused at an intermediate focus 6 to form an image at the intermediate focus 6 of the plasma present in the plasma formation region 4. The image at the intermediate focus 6 acts as a virtual source of the illumination system IL. The radiation source SO is arranged such that the intermediate focus 6 is located at or near an aperture 8 of a closing structure 9 of the radiation source SO.

[0117] [000116] Although Figure 1 illustrates the source SO as a laser-produced plasma (LPP) source, any suitable source may be used to generate EUV radiation, such as a discharge-produced plasma (DPP) source or a free-electron laser (FEL).

[0118] [000117] The projection system PS is connected to an isolated frame. For example, the isolated frame (which may be referred to as a metro frame) may be supported by a base frame, which may be supported on the ground so as to be substantially isolated from external influences (such as vibrations of the base frame). This isolation may be achieved by the use of acoustic vibration-damping mounts that support the isolated frame on the base frame. The acoustic vibration-damping mounts may be actively controlled to isolate vibrations introduced by the base frame and / or by the isolated frame itself.

[0119] [000118] The support structure MT is movably mounted to the insulated frame via a first positioning device. The first positioning device may be used to move and accurately position the patterning device MA relative to the insulated frame (and the projection system PS connected to the frame). The substrate table WT is movably mounted to the insulated frame via a second positioning device. The second positioning device may be used to move and accurately position the substrate W relative to the insulated frame (and the projection system PS connected thereto).

[0120] [000119] The projection system PS has a body or housing defining an interior and an aperture within which two mirrors 13, 14 are disposed, the projection system PS constructed and arranged to project a patterned beam of EUV radiation B' through the aperture and onto a substrate W supported by a substrate table WT.

[0121] [000120] The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. In particular, the projection system PS is configured to project the patterned EUV radiation beam B' onto an exposure area (or illumination area) in an image plane of the projection system PS. The exposure area and the radiation beam B' are generally of the same shape and size in this image plane (which typically coincides with the surface of the substrate W).

[0122] [000121] In use, a number of different target areas of the substrate W (which may correspond to one or more dies) may be exposed sequentially by moving the substrate table WT relative to the projection system PS between exposures (so as to vary which of the target areas are disposed within an exposure area in the image plane). In addition, each such exposure may be a scanning exposure, whereby the substrate table WT is moved in a scanning direction relative to the projection system PS, whereby the target areas being exposed move or scan in the scanning direction through the exposure area. To achieve this functionality, the lithographic apparatus LA is provided with actuators for moving the substrate table WT relative to the projection system PS. These actuators may be considered to form a scanning mechanism configured to control the relative position of the substrate table WT and the projection system PS. For such an embodiment, the lithographic apparatus LA may also be referred to as a lithographic scanner. The scanning mechanism may be configured to position the substrate table such that a substrate supported by the substrate table is located substantially within the image plane. The scanning mechanism may further be configured to move the substrate table to scan the target areas of the substrate through the exposure area.

[0123] [000122] In a lithographic scanner, the exposure area in the image plane of the projection system PS is elongated, and in this image plane (which typically coincides with the surface of the substrate W), the radiation beam B' is generally an elongated band of radiation (either straight or curved). The aperture in the body of the projection system PS (through which the patterned EUV radiation beam B' is projected onto the substrate W) may have a generally similar shape and may be slightly larger than the exposure area and band of radiation. The elongated exposure area or elongated band of radiation in the image plane of the radiation system PS may be referred to as a slit or exposure slit.

[0124] [000123] Generally, in a scanning lithography apparatus LA, the exposure area is elongated and has a long dimension and a short dimension. The short dimension may coincide with the scanning direction of the support structure MT and the long dimension may coincide with the non-scanning direction of the support structure MT. The exposure area may be curved or straight. Below and in the accompanying figures, the non-scanning direction of the lithography apparatus LA is referred to or labelled as the x-direction and the scanning direction of the lithography apparatus LA is referred to or labelled as the y-direction. The direction perpendicular to the exposure area is referred to or labelled as the z-direction. The long dimension (x-direction) of the exposure area is perpendicular to the plane of FIG. 1 and the short dimension (in the y-direction) of the exposure area lies in the plane of FIG. 1.

[0125] [000124] Each point in the exposure area of ​​the image plane will generally receive a cone of radiation (i.e. a radiation beam having a range of angles of incidence). Thus, adjacent to the aperture, the interior of the body of the projection system PS may taper inwardly towards the aperture (in both directions perpendicular to the optical axis of the patterned EUV radiation beam B'). This tapered portion of the housing adjacent to the opening may be described as being generally funnel-shaped and may be referred to as a funnel.

[0126] [000125] The part of the lithographic apparatus LA shown in Figure 1, near the substrate table WT (and substrate W), will now be described with reference to schematic Figures 2A and 2B.

[0127] [000126] Figures 2A and 2B show a system 20 comprising a substrate table WT for supporting a substrate W and part of a projection system PS. Figure 2A shows a cross-section of the system 20 in a plane containing the scanning direction (y-direction), and Figure 2B shows a cross-section of the system 20 in a plane containing the non-scanning direction (x-direction).

[0128] [000127] System 20 forms part of lithographic apparatus LA, which is shown diagrammatically in Figure 1. Figures 2A and 2B show part of the body or housing of the projection system defining an interior 21 and an aperture 22 (only a tapered part of interior 21 proximate aperture 22 is shown). It should be noted that the extent of aperture 22 is greater in the non-scanning direction (see Figure 2B) than in the scanning direction (see Figure 2A).

[0129] [000128] The system 20 further comprises a gas lock arranged to provide a flow of gas away from the interior of the projection system PS through the opening. This gas flow is indicated diagrammatically by arrows 23, indicating that gas is directed to the interior 21 through an aperture in an inner wall of the body or housing of the projection system. The gas flow 23 may comprise any suitable gas, for example hydrogen or nitrogen. The aperture is arranged to direct the gas flow 23 generally towards the opening 22. By doing so, the gas lock protects the interior of the projection system PS from the ingress of contaminants. For example, such contaminants may be prevented from impinging on the mirrors 13, 14, which in turn improves the optical performance of the projection system PS.

[0130] [000129] The system 20 further comprises a barrier 26 defining a surface 27 generally parallel to the substrate table WT (and any substrate W supported thereby). The barrier 26 surrounds a part of the projection system adjacent the aperture 22 and extends away from it. The barrier 26 forms part of, or may be considered to be an extension of, the body or housing of the projection system PS.

[0131] [000130] It will be appreciated that the barrier 26 may be formed from a number of different components.

[0132] [000131] For example, the barrier 26 may comprise a substrate table heat shield (e.g. in the cross-section shown in Figure 2A) which may be arranged to at least partially thermally insulate the substrate table WT (and any substrate W supported thereby) from other parts of the apparatus (e.g. other parts of the lithographic apparatus LA) which may be desired to be maintained at a particular temperature. Such a substrate table heat shield may comprise a water cooled plate.

[0133] [000132] Additionally or alternatively, the barrier 26 may comprise or incorporate one or more mirrors 28 (see FIG. 2B) that may be used as part of a measurement system arranged to measure the position of the substrate table WT relative to the barrier 26 and / or the projection system PS (or equivalently relative to an isolated frame in which the barrier 26 and the projection system PS are mounted). In use, one or more interferometer beams 30 may be emitted towards the substrate table, for example from the isolated frame in which the barrier 26 and the projection system PS are mounted. The interferometer beams 30 are reflected from the substrate table WT towards the mirror 28. The interferometer beams 30 are reflected from the mirror 28 and propagate back to an interferometer device operable to determine the position of the substrate table WT relative to the barrier 26 and / or the projection system PS (or equivalently relative to an isolated frame in which the barrier 26 and the projection system PS are mounted) in a direction generally perpendicular to the plane of the substrate table WT (which may be referred to as the z-direction). Such an interferometer device may also be referred to as a position sensor.

[0134] [000133] The barrier 26 may be provided with additional components, such as an access hatch or door, that can be moved or removed to provide access to the interior 21 of the projection system PS.

[0135] [000134] In an EUV lithography apparatus, in the presence of EUV radiation, for example from radiation beam B', several parts of the apparatus may be exposed to contamination. Parts of the apparatus at substrate level are particularly susceptible to such contamination. When EUV radiation illuminates the substrate W, contaminants may be released from the substrate W. These contaminants may be transported by the gas flow 23 to other parts of the system 20. Contamination of the mirror 28, which may cause a decrease in the accuracy with which the z position of the substrate table WT (relative to the barrier 26) can be determined and / or may require cleaning and / or replacement of the mirror 28, is desirably avoided.

[0136] [000135] As shown diagrammatically in Figure 2B, the system 20 further comprises a spoiler 32, which forms part of the barrier, disposed between the opening 22 and the mirror 28. The spoiler 32 is configured to direct a portion of the gas flow 23 away from the mirror 28, for example in a region 34 that bypasses the mirror 28. Advantageously, this can reduce the concentration of contaminants deposited on the mirror 28.

[0137] [000136] Some embodiments of the present disclosure further comprise at least one deformable partition that either (a) extends partially from the substrate table WT towards a surface 27 facing the substrate table WT when in use (e.g. while the projection system PS is projecting the patterned radiation beam B' onto a substrate W supported by the substrate table WT), or (b) extends partially from the surface 27 facing the substrate table WT towards the substrate table WT when in use (e.g. while the projection system PS is projecting the patterned radiation beam B' onto a substrate W supported by the substrate table WT).

[0138] [000137] In use, the projection system PS projects a patterned radiation beam B' onto a substrate W supported by the substrate table WT, while the substrate table WT is positioned such that a part of the substrate receives the patterned radiation B' from the projection system PS (through the aperture 22). The remaining part of the substrate W faces a generally parallel surface 27, which may, for example, comprise a heat shield.

[0139] [000138] As discussed further below, it may be beneficial to reduce the gap between some parts of the substrate W and the surrounding apparatus (e.g. to reduce the amount of particles and / or radiation passing to or from particular parts of the substrate W). To this end, it may be beneficial to reduce the distance between the substrate table WT (or substrate W) and the facing surface 27. However, since it is undesirable for the substrate W or substrate table WT to contact the facing surface 27, there is a limit to the minimum distance that can be achieved. Furthermore, some tolerance may be allowed to prevent such contact in the event of an earthquake or the like, thereby preventing damage to the substrate W, the substrate table WT or the facing surface 27.

[0140] [000139] Advantageously, at least one deformable partition of a lithographic apparatus according to the present disclosure further reduces the gap between some parts of the substrate W and the surrounding apparatus. The at least one deformable partition extends partially from a first member (at its proximal end) towards a second member (at its distal end). The first and second members are (a) the substrate table WT or (b) a surface 27 facing the substrate table WT in use. When the first and second members move towards each other (e.g. in case of an earthquake), the second member may contact the distal end of the deformable partition and deform it. As the at least one partition is deformable, advantageously such contact will not result in damage to either the substrate table WT or the surface 27 facing it in use (e.g. a heat shield). Thus, advantageously, the lithographic apparatus according to the present disclosure allows the physical gap between the substrate table WT (or substrate W) and an adjacent surface 27 to be reduced while limiting the risk of damage.

[0141] [000140] Some exemplary embodiments of such deformable partitions are described further below with reference to Figures 3 to 17B.

[0142] [000141] In some embodiments of the present disclosure, as will now be described with reference to Figures 3 to 7B, the at least one deformable partition extends partially from the substrate table WT towards a surface 27 that, in use, faces the substrate table WT while the projection system PS projects the patterned radiation beam B' onto a substrate W supported by the substrate table WT.

[0143] [000142] As explained above, the surface 27 facing the substrate table WT may be provided with or at least partly formed by a heat shield.

[0144] [000143] Figure 3 shows a fragment of a substrate table (supporting a substrate W) and a generally parallel barrier 26 without a deformable partition. Also shown in Figure 3 are potential trajectories 36 of particles emitted from the surrounding environment. As represented diagrammatically in Figure 3, these trajectories 36 show that such particles from the surrounding environment can bounce off the barrier 26 and impinge on the substrate W. This is undesirable as it can cause printing errors and, as a result, defects in the integrated circuit.

[0145] [000144] Figure 4 shows the same substrate table WT, substrate W and fragment of barrier 26 as shown in Figure 3. In addition, Figure 4 shows a deformable partition 38 extending part way from the substrate table WT towards the surface 27. Also shown in Figure 4 are potential trajectories 36 of particles emitted from the surrounding environment. As can be seen from a comparison of Figures 3 and 4, some of the potential trajectories 36 that would reach the substrate W in the absence of the deformable partition 38 (see Figure 3) are blocked by the deformable partition 38 (see Figure 4).

[0146] [000145] Advantageously, the deformable partition 38, which extends partly from the substrate table WT to the surface 27, provides a barrier between the part of the substrate table WT supporting the substrate W and a peripheral part of the substrate table WT and the ambient environment. As the deformable partition 38 extends from the substrate table WT, it remains in a fixed position relative to the substrate W supported by the substrate table WT.

[0147] [000146] In order to reduce the occurrence of wafer defects, it is desirable to reduce the number of particles incident on the substrate W. The deformable partition 38 acts to further reduce the ingress of particles from the surrounding environment into the area in which the substrate W is disposed.

[0148] [000147] It will be appreciated that at least one deformable partition 38, which extends partially from the substrate table WT to the surface 27 facing the substrate table WT in use, has a range component at least in a direction perpendicular to the plane of the substrate W (i.e. the z direction).

[0149] [000148] In principle, the at least one deformable partition 38, which extends partly from the substrate table WT towards the surface 27 facing the substrate table, may extend substantially all the way around the periphery (or perimeter) of the area for supporting the substrate W. This would maximise separation between the part of the substrate table WT supporting the substrate W and the peripheral part of the substrate table WT and the surrounding environment.

[0150] [000149] However, in some embodiments, at least one deformable partition 38 that extends partially from the substrate table WT to the surface 27 facing the substrate table extends only partially around the periphery of an area of ​​the substrate table WT that supports the substrate W in use.

[0151] [000150] For example, in some embodiments at least one deformable partition 38, which extends partially from the substrate table WT to the surface 27 facing the substrate table WT, extends along two opposing surfaces of a generally rectangular area of ​​the substrate table WT for supporting the substrate W.

[0152] [000151] Advantageously, such an arrangement allows a line of sight of the laser beam 30 to pass from the surrounding environment to a part of the substrate table WT adjacent that part of the substrate table WT that supports the substrate W. As described above with reference to Figure 2B, such a laser beam 30 may be used as part of an interferometric measurement system, for example to measure the position (e.g. height or z position) of the substrate table WT relative to a reference frame.

[0153] [000152] For example, in an arrangement of system 20 as shown in Figures 2A and 2B above, system 20 may comprise two deformable partitions 38, each extending generally in the non-scanning direction (x-direction) along one of two opposing surfaces of a generally rectangular area of ​​the substrate table WT for supporting the substrate W.

[0154] [000153] In some embodiments, at least one deformable partition 38 may be elastically deformable, as will now be described with reference to Figures 5A to 6B.

[0155] [000154] In a first exemplary embodiment of a deformable partition 38 extending part way from the substrate table WT towards the facing surface 27, the deformable partition 38 is an elastically deformable partition 38a having a component of extent at least in a direction parallel to the plane of the substrate W. Such an elastically deformable partition 38a is shown in Figures 5A and 5B.

[0156] [000155] Figure 5A shows the same fragment of the substrate table WT, substrate W and barrier 26 as shown in Figure 4, with the elastically deformable partition 38a disposed in a nominal position. Figure 5B shows an arrangement as in Figure 5A, but with the substrate table WT and barrier 26 moved together, whereby the barrier 26 contacts and exerts a force on the elastically deformable partition 38a disposed in the nominal position.

[0157] [000156] Rather than simply extending perpendicular to the plane of the substrate W (i.e. only in the z-direction), the elastically deformable partitions 38a extend at an oblique angle to the plane of the substrate W. As can be seen in Figure 5B, upon application of a force from an object (e.g. the barrier 26) generally perpendicular to the plane of the substrate W (i.e. generally in the z-direction), such elastically deformable partitions 38a can bend laterally without damaging themselves or the barrier 26.

[0158] [000157] In a second exemplary embodiment of a deformable partition 38 extending part way from the substrate table WT towards the facing surface 27, the deformable partition 38 is an elastically deformable partition 38b that is elastically deformable in a direction generally perpendicular to the plane of the substrate W (i.e. the z-direction). Such an elastically deformable partition 38b is shown in Figures 6A and 6B.

[0159] [000158] Figure 6A shows the same fragment of the substrate table WT, substrate W and barrier 26 as shown in Figure 4, with the elastically deformable partition 38b disposed in a nominal position. Figure 6B shows an arrangement as in Figure 6A, but with the substrate table WT and barrier 26 moved together, whereby the barrier 26 contacts and exerts a force on the elastically deformable partition 38b disposed in the nominal position.

[0160] [000159] In a direction perpendicular to the plane of the substrate W, the elastically deformable partitions 38b in this embodiment are generally in the form of springs. Upon application of a force from an object (e.g. the barrier 26) generally perpendicular to the plane of the substrate W (i.e. generally in the z-direction), such elastically deformable partitions 38b may compress in that direction.

[0161] [000160] Advantageously, such elastically deformable partitions 38a, 38b can be deformed from a nominal position when their distal ends contact another object 26 (e.g. during an earthquake) and can return to the nominal position when the deformation-causing object is removed.

[0162] [000161] In some embodiments, at least one deformable partition 38 may include a frangible portion between its proximal and distal ends, as will now be described with reference to Figures 7A-7B.

[0163] [000162] In a third exemplary embodiment of a deformable partition 38c extending partially from the substrate table WT towards the facing surface 27, the deformable partition 38c comprises a frangible portion between its proximal and distal ends. Such a deformable partition 38c is shown in Figures 7A and 7B.

[0164] [000163] Figure 7A shows the same substrate table WT, substrate W and fragment of barrier 26 as shown in Figure 4, with the elastically deformable partition 38c arranged in a nominal position. Between a proximal end 42 of the deformable partition 38c and a distal end 44 of the deformable partition 38c, a frangible portion 40 is provided.

[0165] [000164] Figure 7B shows the arrangement of Figure 7A but with the substrate table WT and the barrier 26 moved together so that the barrier 26 contacts and exerts a force on the deformable partition 38c which is disposed in a nominal position.

[0166] [000165] Advantageously, such frangible portions 40 enable the deformable partition 38c to break when its distal end 44 contacts another object (e.g., during an earthquake). Such a deformable partition 38c may be described as permanently deformable.

[0167] [000166] In some embodiments of the present disclosure, as will now be described with reference to Figures 8 to 17B, the at least one deformable partition extends partially towards the substrate table WT, from a surface 27 that, in use, faces the substrate table WT while the projection system PS projects a patterned radiation beam B' onto a substrate W supported by the substrate table WT.

[0168] [000167] The deformable partitions that extend partly from the surface 27 facing the substrate table WT towards the substrate table WT may extend substantially all around the periphery of the exposure area. Alternatively, at least one deformable partition that extends partly from the surface 27 facing the substrate table WT towards the substrate table WT may extend only partly around the periphery of the exposure area.

[0169] [000168] Figure 8 shows a fragment of a substrate table WT (supporting a substrate W) and a part of a generally parallel barrier without a deformable partition. In particular, the barrier comprises a mirror 28 (see Figure 2B) which may be used as part of a measurement system arranged to measure the z-position of the barrier 26 and / or the substrate table WT relative to the projection system PS (or equivalently relative to an isolated frame to which the barrier 26 and projection system PS are mounted). The barrier further comprises a spoiler 32 arranged between the opening 22 and the mirror 28, which forms part of the barrier.

[0170] [000169] Figure 9 shows the same substrate table WT, substrate W and fragment of barrier 26 as shown in Figure 8. In addition, Figure 9 shows a deformable partition 46 extending partly from the surface 27 towards the substrate table WT.

[0171] [000170] In particular, the deformable partition 46 extends from a surface 27 of the spoiler 32 adjacent to a mirror 28 used as part of an interferometric measurement system. In this embodiment, the deformable partition 46 extends generally along the scan direction (i.e. the y-direction).

[0172] [000171] Advantageously, the deformable partition 46 extends partly from the surface 27 facing the substrate table WT towards the substrate table WT during exposure of the substrate W, so that the deformable partition 46 can provide a barrier between the exposure area (also known as a slit) and the surrounding parts of the apparatus. Because the deformable partition 46 extends from the surface 27 facing the substrate table WT, in use, it remains in a fixed position relative to the projection system PS and any other apparatus connected to it.

[0173] [000172] It may be desirable to reduce the number of particles that leave the volume adjacent to the exposure region into the surrounding environment. For example, when EUV radiation illuminates the substrate W, contaminants may be released from the substrate W. These contaminants may be transported by the gas flow 23 (see Figures 2A and 2B) to other parts of the system 20. Contamination of the mirror 28, which may cause a decrease in the accuracy with which the z-position (relative to the barrier 26) of the substrate table WT can be determined and / or may require cleaning and / or replacement of the mirror 28, is desirable to avoid. A deformable partition 46, which extends partly from the surface 27 facing the substrate table WT during exposure of the substrate to the substrate table WT, can achieve this.

[0174] [000173] It will be appreciated that the deformable partition 46, which extends partially from the surface 27 facing the substrate table WT while the projection system PS is projecting a patterned radiation beam towards the substrate table WT onto the substrate W supported by the substrate table WT, has a range component at least in a direction perpendicular to the plane of the substrate W (i.e. in the z direction).

[0175] [000174] In some embodiments, at least one deformable partition 46 may be elastically deformable, as will now be described with reference to Figures 10A to 11B.

[0176] [000175] In a first exemplary embodiment of a deformable partition 46 extending partly from the surface 27 adjacent to a mirror 28 used as part of an interferometric measurement system towards the substrate table WT, the deformable partition 46 is an elastically deformable partition 46a having a component of extent at least in a direction parallel to the plane of the substrate W. Such an elastically deformable partition 46a is shown in Figures 10A and 10B.

[0177] [000176] Figure 10A shows the same fragment of the substrate table WT, substrate W and barrier 26 as shown in Figure 9, with the elastically deformable partition 46a arranged in a nominal position. Figure 10B shows an arrangement as in Figure 10A, but with the substrate table WT and barrier 26 moved together, whereby the substrate W and / or substrate table WT contacts and exerts a force on the elastically deformable partition 46a.

[0178] [000177] Rather than simply extending perpendicular to the plane of the substrate W (i.e. only in the z-direction), the elastically deformable partitions 46a extend at an oblique angle to the plane of the substrate W. As can be seen in Figure 10B, upon application of a force from an object (e.g. the substrate W and / or the substrate table WT) generally perpendicular to the plane of the substrate W (i.e. generally in the z-direction), such an elastically deformable partition 46a can bend laterally without damaging itself or the barrier 26 or the substrate table WT.

[0179] [000178] In a second exemplary embodiment of a deformable partition 46 extending partly from the surface 27 adjacent to a mirror 28 used as part of an interferometric measurement system towards the substrate table WT, the deformable partition 46 is an elastically deformable partition 46b that is elastically deformable in a direction generally perpendicular to the plane of the substrate W (i.e. the z-direction). Such an elastically deformable partition 46b is shown in Figures 11A and 11B.

[0180] [000179] Figure 11A shows the same fragment of the substrate table WT, substrate W and barrier 26 as shown in Figure 4, with the elastically deformable partition 46b arranged in a nominal position. Figure 11B shows an arrangement as in Figure 11A, but with the substrate table WT and barrier 26 moved together, whereby the substrate W and / or substrate table WT contacts and exerts a force on the elastically deformable partition 46b.

[0181] [000180] In a direction perpendicular to the plane of the substrate W, the elastically deformable partition 46b in this embodiment is generally in the form of a spring. Upon application of a force from an object (e.g. the substrate W and / or the substrate table WT) generally perpendicular to the plane of the substrate W (i.e. generally in the z direction), such an elastically deformable partition 46b may compress in that direction.

[0182] [000181] Advantageously, such elastically deformable partitions 46a, 46b can be deformed from a nominal position when their distal ends contact another object 26 (e.g. during an earthquake) and can return to the nominal position when the object causing the deformation is removed.

[0183] [000182] In some embodiments, at least one deformable partition 46 may include a frangible portion between its proximal and distal ends, as will now be described with reference to Figures 12A-12B.

[0184] [000183] In a third exemplary embodiment of a deformable partition 46 extending partially from the surface 27 adjacent to a mirror 28 used as part of an interferometric measurement system towards the substrate table WT, the deformable partition 46c comprises a frangible portion between its proximal and distal ends. Such a deformable partition 46c is shown in Figures 12A and 12B.

[0185] [000184] Figure 12A shows the same substrate table WT, substrate W and fragment of barrier 26 as shown in Figure 9, with the deformable partition 46c arranged in a nominal position. Between a proximal end 50 of the deformable partition 46c and a distal end 52 of the deformable partition 46c, a frangible portion 48 is provided.

[0186] [000185] Figure 12B shows an arrangement as in Figure 12A, but with the substrate table WT and barrier 26 moved together so that the substrate W and / or substrate table WT contacts and exerts a force on the deformable partition 46c.

[0187] [000186] Advantageously, such a frangible portion 40 allows the deformable partition 46c to break when its distal end 44 contacts another object (e.g., during an earthquake). Such a deformable partition 46c may be described as permanently deformable.

[0188] [000187] Figure 13 shows a fragment of a substrate table WT (supporting a substrate W) and a part of the projection system housing close to the opening 22 but without the deformable partition.

[0189] [000188] Figure 14 shows the same substrate table WT as shown in Figure 13, a substrate W and a fragment of a lower part of the projection system housing adjacent to the opening 22. In addition, Figure 14 shows two deformable partitions 54, each extending partly from the housing or projection system towards the substrate table WT.

[0190] [000189] In particular, the deformable partitions 54 extend from and form an extension of a lower portion of the projection system housing adjacent the opening 22. The deformable partitions 54 extend from the projection system near the exposure area. In this embodiment, the deformable partitions 54 each extend generally along the non-scanning direction (i.e. the x-direction).

[0191] [000190] Advantageously, the deformable partition 54 extends partly from a surface facing the substrate table WT towards the substrate table WT during exposure of the substrate W, so that the deformable partition 54 can provide a barrier between the exposure area (also known as a slit) and surrounding parts of the apparatus. Because the deformable partition 54 extends from a surface facing the substrate table WT, in use, it remains in a fixed position relative to the projection system PS and any other apparatus connected to it.

[0192] [000191] It may be desirable to reduce the number of particles that leave the volume adjacent the exposure region into the surrounding environment. For example, when EUV radiation illuminates the substrate W, contaminants may be released from the substrate W. These contaminants may be transported by the gas flow 23 (see Figures 2A and 2B) to other parts of the system 20. Contamination of other parts of the substrate W may cause wafer defects and is desirable to avoid. Additionally or alternatively, it may be desirable to reduce the amount of radiation from the projection system PS that is incident on the substrate W outside the exposure region. A deformable partition 54 extending partly from a surface 27 facing the substrate table WT during exposure of the substrate to the substrate table WT can achieve this.

[0193] [000192] It will be appreciated that the deformable partition 54, which extends partially from a surface facing the substrate table WT while the projection system PS is projecting a patterned radiation beam towards the substrate table WT onto the substrate W supported by the substrate table WT, has a range component at least in a direction perpendicular to the plane of the substrate W (i.e. in the z direction).

[0194] [000193] In some embodiments, at least one deformable partition 54 may be elastically deformable, as will now be described with reference to Figures 15A to 16B.

[0195] [000194] In a first exemplary embodiment of a deformable partition 54 extending from the projection system in the vicinity of the exposure region, the deformable partition 54 is an elastically deformable partition 54a having a component of extent at least in a direction parallel to the plane of the substrate W. Such an elastically deformable partition 54a is shown in Figures 15A and 15B.

[0196] [000195] Figure 15A shows the same substrate table WT, substrate W and fragment of the bottom of the projection system PS as shown in Figure 14, with the elastically deformable partition 54a arranged in a nominal position. Figure 15B shows an arrangement as in Figure 15A, but with the substrate table WT and barrier 26 moved together, so that the substrate W and / or substrate table WT contacts and exerts a force on the elastically deformable partition 54a.

[0197] [000196] Rather than simply extending perpendicular to the plane of the substrate W (i.e. only in the z-direction), the elastically deformable partitions 54a extend at an oblique angle to the plane of the substrate W. As can be seen in Figure 15B, upon application of a force from an object (e.g. the substrate W and / or the substrate table WT) generally perpendicular to the plane of the substrate W (i.e. generally in the z-direction), such an elastically deformable partition 54a can bend laterally without damaging itself or the barrier 26 or the substrate table WT.

[0198] [000197] In a second exemplary embodiment of a deformable partition 54 extending from the projection system in the vicinity of the exposure area, the deformable partition 54 is an elastically deformable partition 54b that is elastically deformable in a direction generally perpendicular to the plane of the substrate W (i.e. the z-direction). Such an elastically deformable partition 54b is shown in Figures 16A and 16B.

[0199] [000198] Figure 16A shows the same substrate table WT, substrate W and fragment of the bottom of the projection system PS as shown in Figure 14, with the elastically deformable partition 54b arranged in a nominal position. Figure 16B shows an arrangement as in Figure 16A, but with the substrate table WT and barrier 26 moved together, so that the substrate W and / or substrate table WT contacts and exerts a force on the elastically deformable partition 54b.

[0200] [000199] In a direction perpendicular to the plane of the substrate W, the elastically deformable partitions 54b in this embodiment are generally in the form of springs. Upon application of a force from an object (e.g. the substrate W and / or the substrate table WT) generally perpendicular to the plane of the substrate W (i.e. generally in the z direction), such elastically deformable partitions 54b may compress in that direction.

[0201] [000200] Advantageously, such elastically deformable partitions 54a, 54b can be deformed from a nominal position when their distal ends contact another object 26 (e.g. during an earthquake) and can return to the nominal position when the deformation-causing object is removed.

[0202] [000201] In some embodiments, at least one deformable partition 54 may include a frangible portion between its proximal and distal ends, as will now be described with reference to Figures 17A-17B.

[0203] [000202] In a third exemplary embodiment of a deformable partition 54 extending from the projection system near the exposure area, a deformable partition 54c comprises a frangible portion between its proximal and distal ends. Such a deformable partition 54c is shown in Figures 17A and 17B.

[0204] [000203] Figure 17A shows the same substrate table WT, substrate W and fragment of the barrier 26 (lower part of the projection system) as shown in Figure 14, with the deformable partition 54c arranged in a nominal position. A frangible portion 56 is provided between a proximal end 58 of the deformable partition 54c and a distal end 60 of the deformable partition 54c.

[0205] [000204] Figure 17B shows an arrangement as in Figure 17A, but with the substrate table WT and barrier 26 moved together so that the substrate W and / or substrate table WT contacts and exerts a force on the deformable partition 54c.

[0206] [000205] Advantageously, such frangible portions 56 enable the deformable partition 54c to break when its distal end 60 contacts another object (e.g., during an earthquake). Such a deformable partition 54c may be described as permanently deformable.

[0207] [000206] Although various embodiments of the deformable partitions 38, 46, 54 have been described separately above, it will be appreciated that other embodiments may include any combination of these deformable partitions 38, 46, 54.

[0208] [000207] The substrate table WT shown in Figures 4 to 7B and described above has also been illustrated and described with reference to a barrier 26 having a surface 27 which, in use, faces and is adjacent to the substrate table WT and the substrate W. Some embodiments of the present disclosure relate solely to a substrate table WT having a deformable partition 38 extending from the substrate table WT generally in the form of the substrate table WT shown in Figures 4 to 7B and described above.

[0209] [000208] The inventors have found that the following methods are most effective for maximizing protection of the substrate W during exposure to the radiation beam B: (a) increasing the pressure between the substrate W and an adjacent body (e.g. a thermal shield), (b) increasing the gas velocity between the substrate W and an adjacent body (e.g. a thermal shield), and (c) reducing the gap between the substrate W and an adjacent body (e.g. a thermal shield). This insight is exploited by several embodiments of the present disclosure, as will now be described.

[0210] [000209] An embodiment of a substrate table 70 arranged to support a substrate W will now be described with reference to Figures 18A to 21. Figure 18A shows a cross-sectional view of the substrate table 70 in an arrangement such that a substrate supported by the substrate table 70 is adjacent to and facing a device such as a heat shield 72. Figure 18B shows a plan view of the substrate table 70 shown in Figure 18A.

[0211] [000210] The substrate table 70 comprises a body 74, a clamp 76 and a partition 78. The body 74 may be provided with a reflective surface for use with an interferometric positioning device (not shown) as is known in the art. The body 74 may also be referred to as a mirror block. The clamp 76 is provided on a surface 80 of the body 74. In use, the clamp 76 is operable to support and to clamp (i.e. provide a clamping force to) the substrate W to the clamp 76. The clamp 76 may comprise an electromagnetic clamp.

[0212] [000211] The partition 78 extends from a surface 80 of the body 74. As best seen in Figure 18B, the partition 78 extends substantially around the circumference of the clamp 76.

[0213] [000212] The substrate table 70 further comprises at least one gas outlet provided in a portion of the surface 80 that lies within the partition 78. In this embodiment, the at least one gas outlet is arranged such that gas delivered thereby flows away from the interface between the clamp 76 and the surface 80, as indicated by arrows 82 in Figure 18A. For example, the at least one gas outlet may be provided between the clamp 76 and the body 74. Alternatively, the at least one gas outlet may be provided between the clamp 76 and the partition 78, adjacent to the clamp 76.

[0214] [000213] The gas 82 provided from the at least one gas outlet may be referred to as a backfill gas. The backfill gas may be provided to a space between the body 74 and the clamp 76 (e.g., between the support burls). Additionally or alternatively, the backfill gas may be provided to a space between the clamp 76 and the substrate W (e.g., between the support burls).

[0215] [000214] At least one gas outlet may be positioned to direct gas flow 82 to a ring around the clamp 76 such that the gas flow 82 is directed away from the clamp 76.

[0216] [000215] Such an arrangement may be referred to as a backfill gas flow shield. In use, a flow of gas (e.g., hydrogen gas) 82 may be injected in a ring around the substrate W such that the flow of gas 82 is directed away from the substrate W, thus moving particles away from the substrate W. This flow of gas 82 thus forms a shield around the clamp 76 and the substrate W.

[0217] [000216] The substrate table 70 may further comprise a gas supply operable to supply gas to the at least one gas outlet. Alternatively, a separate gas supply (which may form part of the lithographic apparatus LA) may be connected to the substrate table 70, which may be operable to supply gas to the at least one gas outlet.

[0218] [000217] In use, the substrate table 70 may be positionable relative to another device 72 such that a surface of the device 72 faces and is adjacent to the substrate W and substrate table 70. When in such a configuration, the partition 78 extends partly from the substrate table 70 towards the surface of the device 72 to create a mini-environment between the part of the substrate table 70 inside the partition 78 and the other device 72.

[0219] [000218] It will be appreciated that the substrate table 70 may, in use, form part of a lithographic apparatus LA of the type shown in Figure 1 (e.g. may be used as the substrate table WT shown in Figure 1). The substrate table 70 may alternatively be referred to as a wafer stage.

[0220] [000219] In use, the substrate table 70 (e.g. a wafer stage of a lithographic apparatus) may be positioned such that at least a part of the substrate faces a substantially parallel surface (of a device 72, such as a heat shield). For example, while the projection system PS projects a patterned radiation beam B' onto a substrate W supported by the substrate table 70, the substrate table 70 is positioned such that a part of the substrate W receives the patterned radiation B' from the projection system PS. The remaining part of the substrate W faces the substantially parallel surface of the device 72, which may comprise, for example, a heat shield.

[0221] [000220] In general, it is desirable to reduce the amount of particles passing through and incident on the substrate W. For example, particles incident on the substrate W may result in yield loss of the lithographic apparatus LA.

[0222] [000221] Advantageously, a partition 78 extending from a surface 80 of the body 74 substantially around the periphery of the clamp 76 defines a mini-environment within the partition 78 in the vicinity of the substrate W (e.g. when another object 72 or device is adjacent to the substrate table 70 parallel to the substrate W). At least one gas outlet is provided in the part of the surface 80 that is within the partition 78, which allows a gas 82 to be provided to this mini-environment. Advantageously, in use, a gas flow 82 is provided from the at least one gas outlet in the vicinity of the substrate table 70 to move particles away from the substrate table 70 and to reduce particle incidence on the substrate W supported by the substrate table. The partition 78 allows the pressure within the mini-environment to be increased for a given gas flow 82 into the mini-environment (compared to an arrangement in which the partition 78 is not provided). In addition, the partition 78, and the mini-environment defined thereby, can allow the gap 84 between the substrate W and an adjacent object 72 (e.g., a heat shield) to be increased without increasing the risk of particles being incident on the substrate W.

[0223] [000222] In Figures 18A and 18B, the dimensions of some parts of the new substrate table 70 have been exaggerated to aid in understanding the embodiment. Figures 19A to 19C show the same substrate table 70 at more realistic dimensions. Figure 19A shows the body 74, clamps 76 and substrate W (i.e. substrate table 70 without partition 78). Figure 19B shows the substrate table 70 with partition 78. And Figure 19C shows the substrate table 70 and partition 78 together.

[0224] [000223] As can be seen in Figures 19B and 19C, the partition 78 includes four walls 88 that together form a generally square frame.

[0225] [000224] As seen in the cross section shown in FIG. 18A, at least one gap 86 is provided between the partition 78 and the surface 80 of the body 74 from which the partition extends. Such gap 86 is not shown in FIGS. 19B and 19C due to the scale of the figures. However, FIG. 20 shows an enlarged side view of one of the walls 88 of the partition 78 and the body 74, where the gap 86 is visible. In this embodiment, the partition 78 comprises four walls 88 and a plurality of spaced apart legs, burls or projections 90 that extend from the surface 80 of the body 74 to one or more of the walls 88. Advantageously, the spaces between the legs, burls or projections 90 provide one or more gaps 86 between the partition 78 and the surface 80 from which the partition extends.

[0226] [000225] Such an arrangement, with the gap 86 between the body 74 and the partition 78, allows the gas flow 82 to leave the mini-environment towards the bottom of the mini-environment (i.e. adjacent the surface 80 of the body 74). Such an arrangement is advantageous as it encourages the gas flow 82 to be directed downward towards the body 74, providing additional protection for the substrate W.

[0227] [000226] It will be appreciated that the partitions 78 extending from the surface 80 of the body 74 have at least a component of extent in a direction perpendicular to the plane of the substrate W. In the embodiment shown in the figures, the partitions 78 extend in a direction perpendicular to the plane of the substrate W.

[0228] [000227] A height 92 of the partition 78 from the surface 80 of the body 74 in a direction perpendicular to the plane of the substrate W may be less than or equal to a height 94 of the substrate W supported by the clamp 78 in a direction perpendicular to the plane of the substrate.

[0229] [000228] That is, in use, the distal (or upper) surface of the substrate W may be higher than the partition 78. In such an arrangement, if an object 72 adjacent to the substrate table 70 (e.g. a heat shield) moves towards the substrate table 70 in use (e.g. in the event of an earthquake), it may contact the substrate W rather than the partition 78. Advantageously, such contact will not result in damage to the partition 78 or the other object 72 (e.g. a heat shield) opposing it in use.

[0230] [000229] As explained above, with the new substrate table 70 the same pressure can be reached with less gas flow in the vicinity of the substrate W and in a larger volume due to the increased gap between the substrate W and the adjacent object 72 (e.g. a heat shield). Advantageously this results in a more uniform pressure reducing the amount of localized pressure peaks and lowering the risk of titanium embrittlement.

[0231] [000230] In particular, the combination of (a) the partition 78 extending from the surface 80 of the body 74 substantially around the circumference of the clamp 76, and (b) at least one gas outlet provided in a portion of the surface 80 that is within the partition 78, allows the pressure within the mini-environment defined by the partition 78 to be increased (to protect the substrate W), while the remainder of the compartment in which the substrate table 70 is disposed can remain at a relatively low pressure. This is beneficial for several reasons. First, it reduces the risk of Paschen discharge of high voltage components in the vicinity of the substrate table 70, e.g., in the compartment in which the substrate table 70 is disposed (which may be referred to as the wafer stage compartment). Second, the lower pressure in the bulk of the substrate table compartment means that there are smaller pressure fluctuations when the substrate table 70 is moving, resulting in less disturbance to (interfering) substrate table 70 positioning measurements. Third, there is no need to inject excess hydrogen gas to maintain high pressure throughout the substrate table compartment. This reduces the amount of (hydrogen) gas required making the device more energy efficient, less expensive (due to less hydrogen) and with lower demands on pumping power.

[0232] [000231] Another advantage of the mini-environment created by the partition 78 is that a given pressure level can be achieved with a significantly lower flow rate injection of (hydrogen) gas in the vicinity of the substrate W, which in turn results in less disturbance to the functionality of the clamp 76 from this gas flow 82. For example, this can aid in the thermal regulation of the clamp 76 and the body 80 and the relaxation functionality of the clamp 76.

[0233] [000232] Another advantage of the substrate table 70 is that radiative heat transfer to the substrate W is reduced, which makes thermal management of the substrate W easier.

[0234] [000233] Another advantage of the substrate table 70 is that the partition 78 also acts as a particle shield. For example, the partition 78 can act as a physical barrier that can reflect particles generated at such high velocities in the substrate table compartment that they would not be blocked by the gas flow 82, keeping such particles away from the substrate W.

[0235] [000234] Figure 21 shows the pressure increase achieved in the vicinity of the substrate W due to the presence of the partition 78 of the substrate table 70 as a function of the partition height 92 relative to the height 94 of the substrate W. The results shown in Figure 21 are the result of a simulation assuming that (a) the height 94 of the substrate W supported by the clamps 78 in a direction perpendicular to the plane of the substrate W is 8 mm, and (b) the gap 84 between the substrate W and an adjacent object 72 (e.g. a heat shield) is 6 mm.

[0236] [000235] From Figure 21 it can be seen that if the height 92 of the partition 78 from the surface 80 of the body 74 in a direction perpendicular to the plane of the substrate W is the same as the height 94 of the substrate W, a 25% pressure increase is achieved. As can also be seen from Figure 21, if the height 92 of the partition 78 is less than the height 94 of the substrate W for machine damage safety reasons or for other reasons, the partition 76 can still provide a significant increase in pressure.

[0237] [000236] Previous testing has shown that the number of particles incident on the substrate W is roughly inversely proportional to the pressure in the vicinity of the substrate W, such that a doubling of the pressure in the vicinity of the substrate W roughly halves the number of particles incident on the substrate W. A 1.25-fold increase in pressure, such as can be achieved by a partition, corresponds to a 1.25-fold improvement in particles per substrate W.

[0238] [000237] 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 have other applications, such as in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0239] [000238] Although specific reference is made herein to embodiments of the invention in relation to lithographic apparatus, embodiments of the invention may be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatus may be generally referred to as lithography tools. Such lithography tools may use vacuum or ambient (non-vacuum) conditions.

[0240] [000239] Although particular reference has been made above to the use of embodiments of the invention in connection with optical lithography, it will be appreciated that the invention may be used in other applications, such as, for example, imprint lithography, and is not limited to optical lithography, where the context permits.

[0241] [000240] 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, a machine-readable medium 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. Furthermore, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be understood that such description is merely for convenience and that such actions actually result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc., and that in performing the actions, actuators or other devices may interact with the physical world.

[0242] [000241] Although specific embodiments of the invention have been described above, it will be appreciated that the invention can be practiced otherwise than as described. The above description is illustrative and not restrictive. Thus, it will be apparent to one skilled in the art that modifications can be made to the invention as described without departing from the scope of the following provisions and claims.

[0243] [000242] Clause 1. A substrate table arranged to support a substrate; a device, the system being configurable in a first configuration such that a surface of the device faces and is adjacent to the substrate and substrate table; at least one deformable partition that (a) extends partially from the substrate table towards a surface of the device when the system is in the first configuration, or (b) extends partially from a surface of the device facing and adjacent to the substrate and substrate table towards the substrate table when the system is in the first configuration; A system comprising: 2. The system of clause 1, wherein the device comprises a projection system configured to project a patterned beam of radiation through an aperture onto a substrate supported by a substrate table. 3. The system of clause 2, wherein the device further comprises one or more components extending from the opening and at least partially defining a surface of the device facing and adjacent to the substrate and substrate table when the system is in the first configuration. 4. The system of any preceding clause, wherein at least one deformable partition extends partially from the substrate table towards a surface of the substrate and device opposite and adjacent to the substrate table when the system is in the first configuration. 5. A system according to clause 4, wherein at least one deformable partition that extends partially from the substrate table towards the surface of the substrate and adjacent device facing the substrate table when the system is in the first configuration extends only partially around the periphery of an area of ​​the substrate table for supporting the substrate. 6. The system of any preceding clause, further comprising a scanning mechanism configured to control the relative position of the substrate table and the device. 7. The system of any preceding clause, wherein at least one deformable partition extends partially towards the substrate table and away from a surface of the substrate and device opposite and adjacent to the substrate table when the system is in the first configuration. 8. The system of clause 7, wherein at least one deformable partition extending partially from the surface of the device facing the substrate and adjacent device when the system is in a first configuration towards the substrate table, comprises at least one deformable partition extending from the projection system in the vicinity of the exposure area. 9. The system of clause 8 when depending directly or indirectly from clause 6, wherein at least one deformable partition extending from the projection system in the vicinity of the exposure area extends generally along a non-scanning direction. 10. A system according to any one of clauses 7 to 9, wherein at least one deformable partition facing the substrate and substrate table when the system is in the first configuration towards the substrate table and partially extending from a surface of an adjacent device comprises at least one deformable partition extending from a surface adjacent a mirror used as part of an interferometric measurement system. 11. The system of clause 10 when depending directly or indirectly from clause 6, wherein at least one deformable partition extending from a surface adjacent to a mirror used as part of the interferometric measurement system extends generally along the scanning direction. 12. The system of any preceding clause, wherein at least one of the at least one deformable partitions is elastically deformable. 13. The system of clause 12, wherein said elastically deformable partition has a component of extent at least in a direction parallel to the plane of the substrate. 14. The system of clause 12, wherein the elastically deformable partition is elastically deformable in a direction generally perpendicular to a plane of the substrate. 15. The system of any preceding clause, wherein at least one of the at least one deformable partitions includes a frangible portion between its proximal and distal ends. 16. A substrate table for use in the system of any preceding clause. 17. A device for use in a system according to any one of clauses 1 to 15. 18. A substrate table arranged to support a substrate, the substrate table comprising at least one deformable partition extending from the substrate table and having a component of extent at least in a direction perpendicular to the plane of the substrate when supported by the substrate table. 19. A substrate table according to clause 18, wherein at least one deformable partition extending from the substrate table extends only partially around a periphery of an area of ​​the substrate table that supports the substrate. 20. A substrate table according to clause 18 or clause 19, wherein at least one of the at least one deformable partitions is elastically deformable. 21. A substrate table according to clause 20, wherein said elastically deformable partition has a component of extent at least in a direction parallel to the plane of the substrate when supported by the substrate table. 22. A substrate table according to clause 20, wherein said elastically deformable partition is elastically deformable in a direction generally perpendicular to the plane of the substrate when supported by the substrate table. 23. The substrate table of any one of clauses 18 to 22, wherein at least one of the at least one deformable partitions comprises a frangible portion between its proximal and distal ends. 24. A substrate table arranged to support a substrate, comprising: The main body, a clamp disposed on a surface of the body, the clamp operable to support the substrate and to clamp the substrate to the clamp; a partition extending from the surface substantially around a circumference of the clamp; at least one gas outlet provided in a portion of the surface that is within the partition; A substrate table comprising: 25. The substrate table of clause 24, wherein at least one gap is provided between the partition and the surface from which the partition extends. 26. A substrate table according to clause 24 or clause 25, wherein the partition comprises one or more walls and a plurality of spaced apart legs, burls or protrusions extending from a surface of the body to the one or more walls. 27. A substrate table according to any one of clauses 24 to 26, wherein the partition extending from a surface of the body extends in a direction perpendicular to the plane of the substrate. 28. A substrate table according to any one of clauses 24 to 27, wherein the height of the partition from the surface of the body in a direction perpendicular to the plane of the substrate is less than the height of the substrate supported by the clamps in a direction perpendicular to the plane of the substrate. 29. The substrate table of any one of clauses 24 to 28, wherein at least one of the at least one gas outlet is provided in the vicinity of the clamp. 30. A substrate table according to any one of clauses 24 to 29, wherein at least one gas outlet is arranged to direct gas flow to a ring around the clamp, whereby gas flow is directed away from the clamp. 31. The substrate table of any one of clauses 24 to 30, further comprising a gas source operable to supply gas to the at least one gas outlet. 32. A substrate table according to any one of clauses 24 to 31; a device, the system being configurable in a first configuration such that a surface of the device faces and is adjacent to the substrate table and a substrate supported thereby; A system comprising: 33. The system of clause 32, wherein the device comprises a projection system configured to project a patterned beam of radiation through an aperture onto a substrate supported by a substrate table. 34. The system of clause 33, wherein the device further comprises one or more components extending from the opening and at least partially defining a surface of the device facing and adjacent to the substrate table when the system is in the first configuration. 35. The system of any one of clauses 32 to 34, further comprising a scanning mechanism configured to control the relative position of the substrate table and the device. 36. A lithographic apparatus comprising a system according to any one of clauses 1 to 15, a substrate table according to any one of clauses 18 to 23, a substrate table according to any one of clauses 24 to 31, or a system according to any one of clauses 32 to 35.

Claims

1. 1. A system for a lithographic apparatus, comprising: a substrate table arranged to support a substrate; a device, the system being configurable in a first configuration such that a surface of the device faces and is adjacent to the substrate and the substrate table; at least one deformable partition (38, 46), (a) extending partially from the substrate table towards the surface of the device when the system is in the first configuration, or (b) extending partially from the surface of the device opposite and adjacent to the substrate and substrate table towards the substrate table when the system is in the first configuration; The system, wherein the at least one deformable partition is for reducing a gap between the device and the substrate table when the system is in the first configuration.

2. The system of claim 1 , wherein the device comprises a projection system configured to project a patterned beam of radiation through an aperture and onto a substrate supported by the substrate table.

3. The system of claim 2 , wherein the device further comprises one or more components extending from the opening and at least partially defining the surface of the device facing and adjacent the substrate and the substrate table when the system is in the first configuration.

4. 4. The system of claim 1 , wherein at least one deformable partition extends partially from the substrate table towards the surface of the device that faces and is adjacent to the substrate and the substrate table when the system is in the first configuration.

5. 5. The system of claim 4, wherein the at least one deformable partition, which extends partially from the substrate table toward the surface of the device facing and adjacent to the substrate table when the system is in the first configuration, extends only partially around a periphery of an area of ​​the substrate table for supporting the substrate.

6. The system of claim 1 , further comprising a scanning mechanism configured to control the relative position of the substrate table and the device.

7. 7. The system of claim 1 , wherein at least one deformable partition extends partially towards the substrate table from a surface of the device facing and adjacent to the substrate and the substrate table when the system is in the first configuration.

8. 8. The system of claim 7 , wherein the at least one deformable partition extending partially from the surface of the device facing and adjacent to the substrate and the substrate table when the system is in the first configuration towards the substrate table comprises at least one deformable partition extending from a projection system in the vicinity of an exposure area.

9. The system of claim 8 when depending directly or indirectly from claim 6, wherein the at least one deformable partition extending from the projection system in the vicinity of an exposure area extends generally along a non-scanning direction.

10. 10. The system of claim 7, wherein the at least one deformable partition extending partially from a surface of the device facing and adjacent to the substrate and the substrate table when the system is in the first configuration towards the substrate table comprises at least one deformable partition extending from a surface adjacent to a mirror used as part of an interferometric measurement system.

11. The system of claim 10 when directly or indirectly dependent on claim 6, wherein the at least one deformable partition extending from a surface adjacent to a mirror used as part of an interferometric measurement system extends generally along a scanning direction.

12. The system of claim 1 , wherein at least one of the at least one deformable partitions is elastically deformable.

13. The elastically deformable partition has a component of extent at least in a direction parallel to the plane of the substrate, or the elastically deformable partition is elastically deformable in a direction generally perpendicular to the plane of the substrate; or The system of claim 12 , wherein at least one of the at least one deformable partitions comprises a frangible portion between its proximal and distal ends.

14. a substrate table arranged to support a substrate, The main body, a clamp disposed on a surface of the body, the clamp operable to support the substrate and to clamp the substrate to the clamp; a partition extending from the surface substantially around a circumference of the clamp; at least one gas outlet provided in a portion of said surface within said partition; A substrate table comprising:

15. A lithographic apparatus comprising a system according to one of claims 1 to 13 or a substrate table according to claim 14.

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