Substrate support eligibility assessment

Abstract

Disclosed herein is an independent quality assessment system for determining at least one operational characteristic of a fluid extraction system of a substrate support, the eligibility assessment system comprising: an extraction support system configured to support two-phase fluid extraction by the fluid extraction system; and a measurement system configured to determine at least one operational characteristic of the fluid extraction system from the two-phase fluid extraction.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 22201001.9 filed on October 12, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to the identification or qualification of a fluid extraction system of a substrate support. Embodiments include a stand-alone tool for determining the performance of a fluid extraction system of a substrate support. Embodiments also include determining the performance of a fluid extraction system of a substrate support while the substrate support is operating within a lithographic apparatus. Background Art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern onto a substrate. For example, a lithographic apparatus can be used to manufacture integrated circuits (ICs). For example, a lithographic apparatus can project a pattern (also often referred to as a "design layout" or "design") of a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate (e.g., a wafer). Known lithographic apparatus include so-called steppers, in which each target portion is illuminated by exposing the entire pattern onto the target portion at once, and so-called scanners, in which each target portion is illuminated by scanning the pattern via a radiation beam in a given direction (the "scanning" direction) while simultaneously scanning the substrate parallel or anti-parallel to this direction.

[0005] As semiconductor manufacturing processes continue to advance, the size of circuit elements has continued to decrease, while the number of functional elements (such as transistors) per device has been steadily increasing for decades, following a trend often referred to as "Moore's Law." To keep up with Moore's Law, the semiconductor industry has been pursuing technologies that can create smaller and smaller features. To project a pattern on a substrate, a lithography device can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features patterned on the substrate. Typical wavelengths used today are 365 nanometers (i-line), 248 nanometers, 193 nanometers, and 13.5 nanometers.

[0006] A further improvement in the resolution of smaller features can be achieved by providing an immersion fluid with a relatively high refractive index, such as water, on the substrate during exposure. The effect of the immersion fluid is to enable imaging of smaller features, since the exposure radiation will have a shorter wavelength in the fluid than in the gas. The effect of the immersion fluid can also be seen as increasing the effective numerical aperture (NA) of the system and also increasing the depth of focus.

[0007] Immersion fluid may be confined by a fluid handling structure to a localized region between the projection system and the substrate of the lithographic apparatus. Summary of the invention

[0008] In an immersion semiconductor manufacturing process, an immersion fluid may be continuously supplied to an irradiation region of a substrate. The substrate is supported by a substrate support. The substrate support includes a fluid extraction system for extracting the supplied immersion fluid.

[0009] The reliability of the manufacturing process depends on the performance of the fluid extraction system. Improper operation of the fluid extraction system may result in the formation of bubbles in the immersion fluid. The presence of bubbles increases the risk of manufacturing defects occurring. It is often necessary to improve the known techniques for qualifying fluid extraction systems in order to determine whether the fluid extraction system is operating within its performance specifications.

[0010] According to a first aspect of the present invention, there is provided an independent qualification assessment system for determining at least one operational characteristic of a fluid extraction system of a substrate support, the qualification assessment system comprising: an extraction support system, the extraction support system being configured to support a two-phase fluid extraction performed by the fluid extraction system; and a measurement system, the measurement system being configured to determine at least one operational characteristic of the fluid extraction system based on the two-phase fluid extraction.

[0011] According to a second aspect of the present invention, there is provided a substrate for determining at least one operational characteristic of a fluid extraction system of a substrate support, the substrate comprising: one or more channels, the one or more channels being located on a major surface of the substrate, the one or more channels being used to accommodate deposited liquid on the major surface of the substrate; wherein an end of each channel is located at an edge of the substrate.

[0012] According to a third aspect of the present invention, there is provided an apparatus comprising: a conformity assessment system according to the first aspect; and a substrate according to the second aspect.

[0013] According to a fourth aspect of the present invention, there is provided an apparatus comprising: an immersion lithography apparatus; and a substrate according to the second aspect.

[0014] According to a fifth aspect of the present invention, a method for determining at least one operating characteristic of a fluid extraction system of a substrate support is provided, the method comprising: depositing a liquid onto a substrate; extracting the liquid from the substrate in a two-phase fluid flow; and determining at least one operating characteristic of the fluid extraction system based on the two-phase fluid extraction.

[0015] Further embodiments, features, and advantages of the present invention, as well as the structure and operation of the various embodiments, features, and advantages of the present invention are described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which corresponding reference numerals indicate corresponding parts, and in which:

[0017] Figure 1 A schematic overview of a lithographic apparatus is depicted;

[0018] Figure 2 and Figure 3 Two different versions of a fluid handling system for a lithographic projection apparatus are depicted in cross section;

[0019] Figure 4 A substrate support without the invention is depicted in cross section;

[0020] Figure 5 schematically illustrates a conformity assessment system for a fluid extraction system of a substrate support according to a first embodiment;

[0021] Figure 6 schematically illustrates a test substrate according to an embodiment;

[0022] Fig. 7A and 7B Schematically illustrating different implementations of the liquid confinement channel according to the embodiment;

[0023] Figure 8 shows hypothetical measurements of the power consumption of the heater 510 during a conformity assessment process;

[0024] Fig. 9 schematically showing part of a lithographic apparatus in a second embodiment; and

[0025] Fig.10 A test substrate according to an embodiment is schematically illustrated.

[0026] The features shown in the drawings are not necessarily drawn to scale, and the sizes and / or arrangements depicted are not limiting. It should be understood that the drawings include optional features that may not be essential to the present invention. In addition, not all features of the device are depicted in each of the drawings, and the drawings may only show some of the components relevant to describing a particular feature. DETAILED DESCRIPTION

[0027] In this document, the terms "radiation" and "beam" are used to cover all types of electromagnetic radiation, including ultraviolet radiation (eg, having a wavelength of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm).

[0028] The terms "reticle", "mask" or "patterning device" as used herein may be broadly interpreted as referring to a general patterning device that can be used to impart a patterned cross-section to an incident radiation beam, the patterned cross-section corresponding to the pattern to be created in a target portion of the substrate. The term "light valve" may also be used in this context. In addition to classical masks (transmissive or reflective masks, binary masks, phase-shift masks, hybrid masks, etc.), other examples of such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0029] Figure 1 A lithographic apparatus is schematically depicted. The lithographic apparatus comprises an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam B (e.g., UV radiation or DUV radiation), a mask support (e.g., a mask table) MT configured to support a patterning device (e.g., a mask) MA and connected to a first positioning device PM configured to accurately position the patterning device MA according to certain parameters, a substrate support (e.g., a substrate table) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioning device PW configured to accurately position the substrate support WT according to certain parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.

[0030] In operation, the illumination system IL receives a radiation beam B from a radiation source SO, for example via a beam transport system BD. The illumination system IL may include various types of optical components for directing, shaping and / or controlling the radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic and / or other types of optical components, or any combination thereof. The illuminator IL may be used to condition the radiation beam B to have a desired spatial and angular intensity distribution in its cross-section at the plane of the patterning device MA.

[0031] The term "projection system" PS as used herein should be broadly interpreted as covering various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optical systems or any combination thereof, as appropriate for the exposure radiation used, and / or other factors, such as the use of immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" PS.

[0032] The lithographic apparatus is of a type in which at least a portion of the substrate W may be covered by an immersion liquid having a relatively high refractive index, such as water, so as to fill an immersion space 11 between the projection system PS and the substrate W, which is also referred to as immersion lithography. More information on immersion technology is given in US 6,952,253, which is incorporated herein by reference.

[0033] The lithographic apparatus may be of a type having two or more substrate supports WT (also known as a "dual stage"). In such a "multi-stage" machine, the substrate supports WT may be used in parallel, and / or a step of preparing a substrate W for subsequent exposure may be performed on a substrate W on one of the substrate supports WT, while another substrate W on another substrate support WT is being used to expose a pattern on another substrate W.

[0034] In addition to the substrate support WT, the lithographic apparatus may comprise a measurement platform (not depicted in the drawings). The measurement platform is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure properties of the projection system PS or properties of the radiation beam B. The measurement platform may hold a plurality of sensors. The cleaning device may be arranged to clean a part of the lithographic apparatus, for example a part of the projection system PS or a part of the system for providing immersion liquid. The measurement platform may be moved under the projection system PS when the substrate support WT is away from the projection system PS.

[0035] In operation, a radiation beam B is incident on a patterning device (e.g. a mask MA) held on a mask support MT and is patterned by a pattern (design layout) present on the patterning device MA. Having passed through the mask MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioning device PW and the position measurement system IF, the substrate support WT can be accurately moved, for example in order to position different target portions C in the path of the radiation beam B in a focused and aligned position. Similarly, the first positioning device PM and possibly a further position sensor (the further position sensor not being in position) are arranged to move the substrate support WT accurately. Figure 1 The patterning device MA may be accurately positioned relative to the path of the radiation beam B using the mask alignment marks M1, M2 and the substrate alignment marks P1, P2. Although the substrate alignment marks P1, P2 occupy dedicated target portions as illustrated, they may be located in spaces between target portions. When the substrate alignment marks P1, P2 are located between target portions C, they are referred to as scribe line alignment marks.

[0036] In order to clearly illustrate the present invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes, namely, an x-axis, a y-axis, and a z-axis. Each of the three axes is orthogonal to the other two axes. The rotation around the x-axis is called an Rx rotation. The rotation around the y-axis is called an Ry rotation. The rotation around the z-axis is called an Rz rotation. The x-axis and the y-axis define a horizontal plane, while the z-axis is in the vertical direction. The Cartesian coordinate system does not limit the present invention, but is only used for illustration. Alternatively, another coordinate system (such as a cylindrical coordinate system) can be used to illustrate the present invention. The orientation of the Cartesian coordinate system can be different, for example, so that the z-axis has a component along the horizontal plane.

[0037] Immersion technology has been introduced into lithography systems to enable improved resolution of smaller features. In an immersion lithography apparatus, a liquid layer of an immersion liquid having a relatively high refractive index is interposed in the immersion space 11 between the apparatus's projection system PS (through which a patterned beam is projected onto the substrate W) and the substrate W. The immersion liquid covers at least the portion of the substrate W that is under the final element of the projection system PS. Thus, at least the portion of the substrate W that is undergoing exposure is immersed in the immersion liquid.

[0038] In commercial immersion lithography, the immersion liquid is water. Typically, the water is high-purity distilled water, such as ultrapure water (UPW) commonly used in semiconductor manufacturing plants. In an immersion system, the UPW is often purified, and the UPW may undergo additional processing steps before being supplied to the immersion space 11 as an immersion liquid. In addition to water, other liquids with a high refractive index may also be used as the immersion liquid, for example: hydrocarbons (such as fluorinated hydrocarbons); and / or aqueous solutions. In addition, it has been envisioned that other fluids other than liquids may be used for immersion lithography.

[0039] In this specification, reference will be made to localised immersion in the description, in which immersion liquid is confined, in use, to the immersion space 11 between the final element and a surface facing the final element. The facing surface is the surface of the substrate W, or a surface of the support platform (or substrate support WT) which is coplanar with the surface of the substrate W. (Note that references to the surface of the substrate W hereinafter also refer additionally or alternatively to the surface of the substrate support WT, unless otherwise expressly stated, and vice versa). A fluid handling structure IH between the projection system PS and the substrate support WT serves to confine the immersion liquid to the immersion space 11. The immersion space 11 filled with immersion liquid is smaller in plane than the top surface of the substrate W, and the immersion space 11 remains substantially stationary relative to the projection system PS while the substrate W and the substrate support WT move underneath.

[0040] Other immersion systems have been envisaged, such as unconfined immersion systems (so-called "all-wet" immersion systems) and bath immersion systems. In an unconfined immersion system, the immersion liquid covers an area larger than the surface below the final component. The liquid outside the immersion space 11 is present as a thin liquid film. The liquid may cover the entire surface of the substrate W, or even the substrate W and a substrate support WT coplanar with the substrate W. In a bath system, the substrate W is completely immersed in a bath of immersion liquid.

[0041] The fluid handling structure IH is a structure that supplies immersion liquid to the immersion space 11, removes immersion liquid from the immersion space 11 and thereby confines the immersion liquid to the immersion space 11. The fluid handling structure IH includes a number of features that are part of a fluid supply system. The arrangement disclosed in PCT patent application publication number WO99 / 49504 is an early fluid handling structure that includes conduits that supply immersion liquid to the immersion space 11 or withdraw immersion liquid from the immersion space 11 and that operate in dependence on relative movement of a platform below the projection system PS. In more recent designs, the fluid handling structure extends along at least a portion of the boundary of the immersion space 11 between the final element of the projection system PS and the substrate support WT or substrate W so as to partially define the immersion space 11.

[0042] The fluid handling structure IH can have a range of different functions. Each function can be derived from a corresponding feature that enables the fluid handling structure IH to achieve the function. The fluid handling structure IH can be referred to by many different terms, each term referring to a function, such as a barrier member, a sealing member, a fluid supply system, a fluid removal system, a liquid confinement structure, and the like.

[0043] As a barrier member, the fluid handling structure IH is a barrier to the flow of immersion liquid from the immersion space 11. As a liquid confinement structure, the structure confines immersion liquid to the immersion space 11. As a sealing member, the sealing features of the fluid handling structure IH form a seal for confining immersion liquid to the immersion space 11. The sealing features may include an additional gas flow (such as an air knife) from an opening in the surface of the sealing member.

[0044] The fluid handling structure IH may supply immersion fluid and is therefore a fluid supply system.

[0045] The fluid handling structure IH may at least partially confine immersion fluid and thereby be a fluid confinement system.

[0046] The fluid handling structure IH may provide a barrier to immersion fluid and thereby be a barrier member, such as a fluid confinement structure.

[0047] The fluid handling structure IH may create or use gas flows, for example to help control the flow and / or position of the immersion fluid.

[0048] The gas flow may form a seal for confining the immersion fluid and therefore the fluid handling structure IH may be referred to as a sealing member; this sealing member may be a fluid confinement structure.

[0049] An immersion liquid may be used as the immersion fluid. In this case, the fluid handling structure IH may be a liquid handling system. With reference to the preceding description, references in this paragraph to features defined relative to a fluid may be understood to include features defined relative to a liquid.

[0050] The lithographic apparatus has a projection system PS. During exposure of the substrate W, the projection system PS projects a patterned radiation beam onto the substrate W. In order to reach the substrate W, the path of the radiation beam B passes from the projection system PS through an immersion liquid, which is confined between the projection system PS and the substrate W by a fluid handling structure IH. The projection system PS has a lens element in contact with the immersion liquid, which is the last element in the path of the beam. This lens element in contact with the immersion liquid may be referred to as a "last lens element" or a "final element". The final element is at least partially surrounded by the fluid handling structure IH. The fluid handling structure IH may confine the immersion liquid below the final element and above the facing surface.

[0051] like Figure 1 As shown, the lithographic apparatus comprises a controller 500. The controller 500 is configured to control a substrate table WT.

[0052] Figure 2 A local liquid supply system or fluid handling system is schematically depicted. The liquid supply system is provided with a fluid handling structure IH (or liquid confinement structure) which extends along at least a part of the boundary of the space 11 between the last element of the projection system PS and the support table WT or substrate W. The fluid handling structure IH is substantially stationary relative to the projection system PS in the XY plane, but there may be some relative movement in the Z direction (direction of the optical axis). In examples, a seal is formed between the fluid handling structure IH and the surface of the substrate W and may be a non-contact seal, such as a gas seal (such a system with a gas seal is disclosed in EP1,420,298) or a liquid seal.

[0053] The fluid handling structure IH at least partially confines immersion liquid in a space 11 between the last element of the projection system PS and the substrate W. The space 11 is at least partially formed by the fluid handling structure IH located below and surrounding the final element of the projection system PS. Immersion liquid is brought into the space 11 below the projection system PS and within the fluid handling structure IH through one of the liquid openings 13. Immersion liquid can be removed through another liquid opening 13. Immersion liquid can enter the space 11 through at least two liquid openings 13. Which of the liquid openings 13 is used for supplying immersion liquid and optionally which is used for removing immersion liquid may depend on the direction of movement of the support table WT.

[0054] The immersion liquid can be confined in the space 11 by a non-contact seal such as a gas seal 16 formed by gas, which is formed between the bottom of the fluid handling structure IH and the surface of the substrate W during use. The gas in the gas seal 16 is provided to the gap between the fluid handling structure IH and the substrate W via the inlet 15 under pressure. The gas is extracted via the outlet 14. The overpressure on the gas inlet 15, the vacuum level on the outlet 14 and the geometry of the gap are arranged so that there is an inward high-speed gas flow that confines the immersion liquid. Such a system is disclosed in US2004 / 0207824, the entire contents of which are incorporated herein by reference. In the example, the fluid handling structure IH does not have a gas seal 16.

[0055] Figure 3 is a side cross-sectional view depicting another liquid supply system or fluid handling system. Figure 3 The arrangement shown and described below can be applied to the above-mentioned and Figure 1 The liquid supply system is provided with a fluid handling structure IH (or liquid confinement structure) which extends along at least a part of a boundary of a space 11 between the support table WT or substrate W and a final element of the projection system PS.

[0056] The fluid handling structure IH at least partially confines the immersion liquid in a space 11 between the final element of the projection system PS and the substrate W. The space 11 is at least partially formed by the fluid handling structure IH located below and surrounding the final element of the projection system PS. In the example, the fluid handling structure IH comprises a body member 53 and a porous member 33. The porous member 33 is plate-shaped and has a plurality of holes (i.e., openings or orifices). The porous member 33 may be a mesh in which a plurality of small holes 84 are formed in the mesh. Such a system is disclosed in US2010 / 0045949 A1, the entire contents of which are incorporated herein by reference.

[0057] The main body member 53 includes a supply port 72 capable of supplying immersion liquid to the space 11 and a recovery port 73 capable of recovering immersion liquid from the space 11. The supply port 72 is connected to a liquid supply device 75 via a passage 74. The liquid supply device 75 is capable of supplying immersion liquid to the supply port 72 through the corresponding passage 74. The recovery port 73 is capable of recovering immersion liquid from the space 11. The recovery port 73 is connected to a liquid recovery device 80 via a passage 79. The liquid recovery device 80 recovers the immersion liquid recovered via the recovery port 73 through the passage 29. The porous member 33 is disposed in the recovery port 73. The space 11 is formed between the projection system PS and the fluid handling structure IH on one side and the substrate W on the other side by performing a liquid supply operation using the supply port 72 and a liquid recovery operation using the porous member 33.

[0058] Figure 4 A portion of a lithographic apparatus not in accordance with the present invention is shown, but is used to illustrate features of the present invention. Figure 4 The arrangement shown and described below can be applied to the above-mentioned and Figure 1 The lithography apparatus shown. Figure 4 is a cross-sectional view of a substrate support 20 and a substrate W. In an embodiment, the substrate support 20 comprises one or more regulating channels 61 of a thermal regulator 60, which will be described in more detail below. A gap 5 exists between an edge of the substrate W and an edge of the substrate support 20. When the edge of the substrate W is imaged or at other times, such as when the substrate W is first moved under the projection system PS (as described above), the immersion space 11 filled with liquid, such as by the fluid handling structure IH, will at least partially pass through the gap 5 between the edge of the substrate W and the edge of the substrate support 20. This may result in liquid entering the gap 5 from the immersion space 11.

[0059] The substrate W is held by a support 21 (e.g., a protrusion or a protruding platform) comprising one or more protuberances 41 (i.e., a protrusion from a surface). The support 21 is an example of an object holder. Another example of an object holder is a mask holder. The negative pressure applied between the substrate W and the substrate support 20 helps to ensure that the substrate W is firmly held in place. However, if an immersion liquid is between the substrate W and the support 21, this may cause difficulties, particularly when unloading the substrate W.

[0060] In order to handle immersion liquid entering the gap 5, at least one drain 10, 12 is provided at the edge of the substrate W to remove immersion liquid entering the gap 5. Figure 4 In the embodiment of the present invention, two discharge parts 10, 12 are shown, but there may be only one discharge part or there may be more than two discharge parts. In the embodiment, each discharge part 10, 12 is annular so that the entire periphery of the substrate W is surrounded.

[0061] The primary function of the first drain 10 (which is radially outward of the edge of the substrate W / support 21) is to help prevent bubbles of gas from entering the immersion space 11 of the liquid in the fluid handling structure IH. Such bubbles may adversely affect the imaging of the substrate W. The first drain 10 is provided to help avoid gas in the gap 5 escaping into the immersion space 11 in the fluid handling structure IH. If gas does escape into the immersion space 11, this may cause bubbles to float within the immersion space 11. Such bubbles, if in the path of the projection beam, may cause imaging errors. The first drain 10 is configured to remove gas from the gap 5 between the edge of the substrate W and the edge of a recess in the substrate support 20 in which the substrate W is placed. The edge of the recess in the substrate support 20 may be defined by a cover ring 101, which may be optionally separated from the support 21 of the substrate support 20. The cover ring 101 may be shaped as a ring in a plane and surround the outer edge of the substrate W. The first drain 10 extracts primarily gas and only a small amount of immersion liquid.

[0062] The second drain 12 (which is radially inward of the edge of the substrate W / support 21) is provided to help prevent liquid that reaches under the substrate W from the gap 5 from interfering with the effective release of the substrate W from the substrate table WT after imaging. The provision of the second drain 12 reduces or eliminates any problems that may occur due to liquid that reaches under the substrate W.

[0063] like Figure 4 As shown, in one embodiment, the lithographic apparatus includes a first extraction channel 102 for a passage through which a two-phase flow passes. The first extraction channel 102 is formed in a block. The first discharge portion 10 and the second discharge portion 12 are each provided with a corresponding opening 107, 117 and a corresponding extraction channel 102, 113. The extraction channels 102, 113 are fluidically connected to the corresponding openings 107, 117 through corresponding passages 103, 114.

[0064] like Figure 4 As shown, the cover ring 101 has an upper surface. The upper surface extends circumferentially around the substrate W on the support body 21. In use of the lithographic apparatus, the fluid handling structure IH moves relative to the substrate support 20. During this relative movement, the fluid handling structure IH moves across the gap 5 between the cover ring 101 and the substrate W. In an embodiment, the relative movement is caused by the substrate support 20 moving below the fluid handling structure IH. In an alternative embodiment, the relative movement is caused by the fluid handling structure IH moving above the substrate support 20. In another alternative embodiment, the relative movement is provided by the movement of the substrate support 20 below the fluid handling structure IH and the movement of the fluid handling structure IH above the substrate support 20. In the following description, the movement of the fluid handling structure IH will be used to represent the relative movement of the fluid handling structure IH relative to the substrate support 20.

[0065] As described above, there is a first drain 10 configured to primarily extract gas and immersion liquid. The first drain 10 is provided to help prevent bubbles of gas from entering the immersion space 11 of liquid in which the fluid handling structure IH is present. Such bubbles may adversely affect the imaging of the substrate W. The first drain 10 is configured to remove immersion liquid and gas from the gap 5 between the edge of the substrate W and the edge of the recess in the substrate support 20, WT in which the substrate W is placed. Therefore, the extraction through the first drain 10 is a two-phase flow. The fluid extraction through the first drain 10 can be supported by a system including one or more pumps, flow controllers and other equipment. The fluid flow through the first drain 10 can be referred to as external extraction. The system that supports the fluid flow through the first drain 10 can be referred to as an external extraction system.

[0066] There is also a second drain 12 configured to extract the gas and immersion liquid that have flowed under the substrate W. The extraction through the first drain 12 can also be a two-phase flow. The fluid flow through the second drain 12 can be referred to as an internal extraction. The system that supports the fluid flow through the second drain 12 can be referred to as an internal extraction system.

[0067] The occurrence of bubbles is a particularly serious problem, which can lead to manufacturing defects in many tube cores. The inventors have realized that the occurrence of bubbles depends on the performance of fluid extraction, in particular the performance of the external extraction system. The risk of bubble occurrence can be reduced by ensuring that the external extraction system meets its performance specifications. If the rate of external fluid extraction is too low, bubble formation may increase. If the rate of external fluid extraction is too high, other problems may occur, such as undesirable thermal effects.

[0068] Known techniques for determining the performance of an external extraction system include performing a dry flow test and measuring the geometry of portions of the external extraction system. A dry flow test involves measuring the pressure drop that occurs when the external extraction system extracts only air. However, a dry flow test does not provide an accurate determination of the performance of the external extraction system. A dry flow test uses a single-phase flow (i.e., gas only), whereas actual operation of an external extraction system uses a two-phase flow (i.e., liquid and gas). Furthermore, a dry flow test does not provide an indication of local performance, i.e., does not provide extraction performance at a specified location on the external extraction system.

[0069] Embodiments provide improved techniques for determining the performance of an external extraction system. More generally, embodiments provide improved techniques for determining the performance of a fluid extraction system of a substrate support WT. Improved qualification of the fluid extraction system reduces the likelihood of bubbles occurring due to the fluid extraction system failing to meet its performance specifications. This in turn improves the reliability of the manufacturing process and reduces downtime of the lithographic apparatus.

[0070] Figure 5 A qualification assessment system for a fluid extraction system of a substrate support WT according to a first embodiment is schematically shown.The qualification assessment system of the first embodiment may be a stand-alone tool with the specific purpose of determining the performance of a fluid extraction system of a substrate support WT.

[0071] The conformity assessment system may include a conformity assessment system support frame 502 having a container for a substrate support WT. The conformity assessment system support frame 502 is configured to support standard operation of a fluid extraction system of the substrate support WT. Properties of the fluid extraction system are measured with a substrate W loaded on the substrate support WT. The conformity assessment system may include a tool 511 for properly positioning the substrate W on the substrate support WT. The tool 511 may, for example, include a shim for centering the substrate W on the substrate support WT.

[0072] The conformity assessment system may comprise a liquid deposition system 512 arranged to deposit a liquid 516 onto a major surface of a substrate W held by a substrate support WT. The liquid deposition system 512 may comprise an automatically controlled liquid supply. A fluid extraction system of the substrate support WT may be arranged to extract the deposited liquid 516.

[0073] The conformity assessment system support frame 502 may include a vacuum system ( Figure 5 5 (not shown) and a conduit 501 for extracting and receiving fluid from a fluid extraction system of the substrate support WT. The fluid received by the conduit 501 may come from at least an external extraction system of the substrate support WT. Additionally, the fluid received by the conduit 501 may come from an internal extraction system of the substrate support WT.

[0074] The conformity assessment system may be arranged to measure the properties of a fluid extracted from at least an external extraction system. To this end, the conformity assessment system may also include one or more pressure sensors 503, a liquid / gas separator 505, and a flow meter 508, wherein the pressure sensor is arranged to measure the fluid pressure in the (multiple) conduits 501 including the extracted fluid. The liquid / gas separator 505 may receive a fluid flow from the conduit 501. The received fluid flow may include both a liquid (e.g., a deposition liquid 516) and a gas. The liquid / gas separator 505 may separate the received fluid flow into separate liquid and gas flows. The liquid flow may flow out of the conformity assessment system through the liquid extraction conduit 506. The gas flow may pass through the flow meter 508. The flow meter 508 (which may be a mass flow meter 508) may measure the flow rate of the gas. The gas that has flowed through the flow meter 508 may flow out of the conformity assessment system through the gas extraction conduit 509.

[0075] The conformity assessment system may further include an on / off valve 504. The on / off valve 504 may be arranged between one of the pressure sensors 503 and the liquid / gas separator 505. The open and closed states of the valve 504 may respectively allow and prevent the receipt of the extracted fluid. The conformity assessment system may further include a flow regulating valve 507. The flow regulating valve 507 may be arranged between the liquid / gas separator 505 and the flow meter 508. The pressure of the gas may be controlled by the operation of the flow regulating valve 507.

[0076] The conformity assessment system may include a measurement system for determining the operating characteristics of the fluid extraction system. The measurement system may include a plurality of different components for determining the operating characteristics. For example, the measurement system may include a temperature sensor, a pressure sensor 503, a flow meter 508, and other components for determining the operating characteristics.

[0077] The determined operational characteristics may include measurements of thermal characteristics of the fluid extraction. In particular, the qualification system may include one or more heaters 510 for heating at least a portion of the substrate support WT. Figure 5 514. Although not shown in the figure, the conformity assessment system may also include a temperature sensor for measuring the temperature of at least a portion of the substrate support WT and / or an electrical power sensor arranged to measure the power consumption of the one or more heaters 510. The data measured by the temperature sensor and / or the electrical power sensor may be transmitted to the processor 514.

[0078] The determined operational characteristic may comprise a video recording of the extraction of the deposited liquid 516 . In particular, the conformity assessment system may comprise a camera 513 arranged to record a video of the extraction of the deposited liquid 516 from the main surface of the substrate W. The video recording may be transmitted to a processor 514 .

[0079] The determined operating characteristics may include measurements made by any component of the measurement system. All operating characteristics may be transmitted to the processor 514. The processor 514 may be arranged to receive operating characteristics from a temperature sensor, a pressure sensor 503, a flow meter 508, any other sensor, an on / off valve 504, a flow regulating valve 507, any other valve, and any other component of the measurement system.

[0080] The processor 514 can generate one or more performance characteristics of the fluid extraction system based on the operating characteristics. The determined performance characteristics may include fluid extraction time and / or fluid extraction rate. In particular, the processor 514 can determine the fluid extraction time / rate based on the thermal characteristics of the fluid extraction. Additionally or alternatively, the processor 514 can determine the fluid extraction time / rate based on a video recording of the fluid extraction. The processor 514 can compare the determined one or more performance characteristics with the performance specification to determine whether the fluid extraction system is operating correctly. One or more performance characteristics and the determination of correct or incorrect operation can be presented to an operator of the conformity assessment system on a display 515. The display 515 can be part of a computing system (such as a laptop computer) having processing capabilities. Additionally, a computing system including the display 515 can perform some or all of the tasks of the processor 514.

[0081] Additionally, the processor 514 may be arranged to control the operation of the conformity assessment system.

[0082] For qualification of the fluid extraction system of the substrate support WT, a specially configured test substrate W may be used. Figure 6 A possible configuration of a test substrate W is schematically shown. The test substrate W has a main surface 601. One or more liquid confinement channels 602, which may also be referred to as rivulet, are provided on the main surface 601. There may be a central liquid deposition area 604 in the middle of the main surface 601. The one or more liquid confinement channels 602 may include a deposition liquid 603. The deposition liquid 603 may be an immersion fluid. The deposition liquid 603 may be deposited by a liquid deposition system 512. The deposition liquid 603 may be deposited directly into the one or more liquid confinement channels 602. Alternatively, the deposition liquid 603 may be deposited into the central liquid deposition area 604 and then flow into the one or more liquid confinement channels 602.

[0083] Despite Figure 6 Not shown in the figure, but markings can be provided next to each liquid restriction channel 602. The markings can be printed or written on the main surface 601. When the liquid flows along each liquid restriction channel 602, the markings can help determine the liquid flow rate.

[0084] Fig. 7A and 7B Different implementations of the liquid confinement channel 602 according to embodiments are schematically shown. Fig. 7A and 7B All show that through Figure 6 The cross section of the liquid confinement channel 602 including the deposited liquid 603, 703 is indicated by the line AA in FIG. Fig. 7A and7B The deposited liquid 703 is shown contacting only one side of the liquid confinement channel 602 , but the deposited liquid 703 will typically contact both sides of the liquid confinement channel 602 .

[0085] exist Fig. 7A In the embodiment shown, the test substrate W is coated with a layer 701 of a material having low hysteresis, such as a photoresist layer. Two channel walls 702 are formed on the layer 701. The two channel walls 702 hold the liquid 703 within the liquid confinement channel 602. Each channel wall 702 can be, for example, a tape that has been directly adhered to the main surface 601 of the test substrate W.

[0086] exist Figure 7B In the illustrated embodiment, different regions of the same surface of the test substrate W are coated with different types of materials. The first coating 704a may be a first type of photoresist layer. The second coating 704b is disposed between regions of the first coating 704a. The second coating 704b may be a layer less hydrophobic than the first coating 704a. The second coating 704b may be a second type of photoresist layer. The first coating 704a and the second coating 704b may include different materials. The boundary between the first coating 704a and the second coating 704b defines the edge of the liquid confinement channel 602. Therefore, the liquid 703 is confined between the boundaries.

[0087] The operation of the conformity assessment system is described below.

[0088] The substrate support WT is loaded into the qualification assessment system. A test substrate W (which may be dry) is then loaded onto the substrate support WT. The tool 511 may then center the test substrate W on the substrate support WT. A liquid 516, 603, 703 (which may be an immersion fluid) may then be deposited onto the test substrate W. The deposited liquid 516, 603, 703 is confined within one or more liquid confinement channels 602, such as Figure 6 Initially the fluid extraction system of the substrate support WT may be turned off so that the deposition liquid 516, 603, 703 remains on the main surface 601 of the test substrate W. The one or more heaters 510 may be turned on and there may be a waiting period to allow the temperature of the substrate support WT to reach a steady state.

[0089] To start the qualification process, the on / off valve 504 may be opened and the vacuum system may be started. The fluid extraction system then extracts the deposition liquid 516, 603, 703. The deposition liquid 516, 603, 703 flows along one or more liquid confinement channels 602 and over the edge of the test substrate W. Figure 6As shown, the end of the one or more liquid confinement channels 602 covers only a portion of the circumference of the test substrate W. Thus, the fluid extraction system receives a two-phase flow that is a mixture of liquid and gas.

[0090] During fluid extraction, a measurement system of the conformity assessment system may determine one or more operational characteristics of the fluid extraction system.

[0091] As described above, the determined operating characteristics may include measurements of thermal characteristics of the fluid extraction and / or video recording of the extraction of the deposited liquid 516 , 603 , 703 .

[0092] The thermal characteristic may be measured by a temperature sensor.Alternatively or additionally, the thermal characteristic may be determined by an electrical power sensor. Figure 8 1 shows hypothetical measurements of the power consumption of the heater 510 during the conformity assessment process. The power supply to the heater 510 may be controlled by a feedback loop so that the heater 510 is operated to maintain a substantially constant temperature. Prior to t0, the conformity assessment process has not yet begun and the heater power is not required, or is stabilized at a constant level (at Figure 8 '0' in FIG. 8 ). The qualification process starts at time t0. The qualification process can be started by opening the on / off valve 504. The heater power increases due to the cooling effect of the extracted liquid and gas. The liquid flow leaving the main surface 601 of the test substrate W ends at time t1. The heater power is substantially constant in the time period 801 from t0 to t1. After t1, the heater power may increase significantly due to the cooling effect (especially the evaporation of the residual liquid). Figure 8 The characteristics of the power distribution in can be used to determine the two-phase fluid extraction properties of the fluid extraction system. For example, time period 801 can be used to determine the liquid extraction time.

[0093] Embodiments include operational characteristics determined in other ways and / or using other components of the conformity assessment system. For example, liquid extraction time and / or flow rate can be determined automatically or manually based on measurements of extracted gas flow rate, liquid mass, electrodes, optical sensors, electrical connections to the test substrate W, resistance measurements for the presence of liquid, capacitance measurements for the presence of liquid, weight measurements to determine the presence of liquid, and by other techniques.

[0094] The processor 514 may determine one or more performance characteristics based on the determined operating characteristics. For example, as described above, the processor 514 may determine the fluid extraction time based on the thermal characteristics. Some of the determined operating characteristics may be used directly as performance characteristics.

[0095] Processor 514 may compare one or more performance characteristics to the performance specifications to determine whether the fluid extraction system is functioning properly or improperly.

[0096] Thus, the first embodiment described above provides an independent qualification system for determining whether the performance of the fluid extraction system of the substrate support WT meets the performance specification. Advantageously, this allows a defective fluid extraction system to be detected and the defect to be corrected. This improves the reliability of the substrate support WT and reduces the risk of bubbles appearing.

[0097] According to a second embodiment, the conformity assessment process is performed in the lithographic apparatus rather than in a stand-alone tool.

[0098] The lithographic apparatus may have any / all other features or components of the lithographic apparatus as described above. For example, the lithographic apparatus may optionally include at least one or more of a source SO, an illumination system IL, a projection system PS, a substrate support WT, etc. Specifically, the lithographic apparatus may include a projection system PS configured to project a radiation beam B toward an area of ​​a surface of a substrate W. The lithographic apparatus may also include a substrate support 20, WT as described in any of the above embodiments and variations.

[0099] Fig. 9 A portion of a lithographic apparatus is schematically shown. The lithographic apparatus comprises a projection system PS having a fluid handling structure IH, which projection system PS may be the same as that described above with reference to Figure 2 or Figure 3 The projection system PS described is substantially the same. The lithographic apparatus further comprises a substrate support 20, WT, which may be the same as that described above with reference to Figure 4 The described substrate support 20 is substantially the same. The fly height 901 is the distance between the lower surface of the fluid handling structure IH and the upper surface of the substrate W held by the substrate support 20, WT.

[0100] Fig.10 A test substrate W is schematically shown which may be used by a lithographic apparatus during a qualification assessment process.

[0101] The test substrate W has a main surface 1001. One or more liquid confinement channels 1002 (which may also be referred to as flow channels) are provided on the main surface 1001. There may be a central liquid deposition area 1003 in the middle of the main surface 1001. The liquid confinement channels 1002 may confine the liquid flow.

[0102] The size and shape of the central liquid deposition area 1003 may be substantially the same as the opening for allowing immersion fluid to flow out of the fluid handling structure IH to the substrate W. Immersion fluid from the fluid handling structure IH may be deposited into the central liquid deposition area 1003. From the central liquid deposition area 1003, the immersion fluid may flow into the one or more liquid confinement channels 1002.

[0103] The one or more liquid confinement channels 1002 of the test substrate W may be provided by the channel walls or by differences in the hydrophobic properties of the surface of the test substrate W, as previously described with reference to Fig. 7A and 7B as described.

[0104] The process of performing the conformity assessment process may include first loading a test substrate W into a lithographic apparatus, such as Fig. 9 As shown. The projection system PS can then be positioned above the test substrate W. The flying height 901 and flow rate of the immersion fluid can be adjusted and the central liquid deposition area 1003 filled with immersion fluid so that the liquid confinement channel 1002 is filled with immersion fluid supplied from, for example, the liquid opening 13 or supply port 72 of the fluid handling structure IH or an external source. The fluid extraction system of the substrate support 20, WT can also be operated as standard. The flow of immersion fluid and operation of the fluid extraction system can then be stopped, leaving the liquid confinement channel 1002 filled with immersion fluid. The test substrate W can then be removed from the projection system PS, optionally by means of a chuck exchange.

[0105] The qualification process of the fluid extraction system may then be started by turning on the fluid extraction system. Only the external fluid extraction system may be turned on, or both the external and internal fluid extraction systems may be turned on. To determine performance characteristics, the heater power of portions of the substrate support 20, WT may be monitored. In particular, by using a reference Figure 8 The described technique can determine the fluid extraction time based on the change in heater power required. It can then be determined whether the substrate support 20, WT meets the performance specifications.

[0106] According to a third embodiment, the lithographic apparatus of the second embodiment is adapted to comprise further means for determining an operating characteristic.

[0107] For example, the lithographic apparatus may be adapted to include a camera ( Fig. 9 The camera may be located near the projection system PS, or at any other location that allows the camera to record the extraction of fluid at a location to which the test substrate W can be moved. The lithographic apparatus may also be adapted to include an illumination system ( Fig. 91002). The illumination system may for example comprise an LED which may be switched on for each video recording to increase the contrast of the recorded video. As described for the second embodiment, the central liquid deposition area 1003 may be filled with immersion fluid such that the liquid confinement channel 1002 is filled with immersion fluid. The fluid extraction system of the substrate support 20, WT may also be operated according to standard. The flow of immersion fluid and the operation of the fluid extraction system may then be stopped, leaving the liquid confinement channel 1002 filled with immersion fluid. The test substrate W may then be moved such that the camera may record the fluid extraction. Advantageously, the measured operational characteristics may therefore comprise a video recording of the fluid extraction. The camera may also be used for other purposes, such as detecting contamination.

[0108] Other ways in which the lithographic apparatus of the second embodiment may be employed include using an external fluid source to deposit the liquid 516, 603, 703 on the test substrate W and / or providing a new fluid inlet.

[0109] Embodiments include many modifications and variations of the above-described techniques.

[0110] The use of the automated liquid deposition system 512 is optional. Embodiments include the liquid being manually deposited on the test substrate W by an operator of the conformity assessment system. For example, the liquid may be deposited by a syringe.

[0111] Embodiments include many other configurations of test substrates W. For example, a test substrate having only a single liquid confinement channel 602, 1002 may be used.

[0112] On the test substrate W, the ends of the liquid confinement channels 602, 1002 provide well-defined areas on the circumference of the test substrate W, where only liquid flows over the edge of the substrate W during the fluid extraction process. The qualification test can be repeated with different angular orientations of the test substrate W to test whether the fluid extraction properties of the fluid extraction system vary around the circumference of the substrate W. Thus, the two-phase fluid extraction performance of the fluid extraction system can be measured locally.

[0113] Although specific reference may be made herein to the use of lithographic apparatus in IC manufacturing, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection modes for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

[0114] Where 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 by 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 that can be read by a machine (e.g., a computing device). For example, a machine-readable medium may include a read-only memory (ROM); a random access memory (RAM); a magnetic storage medium; an optical storage medium; a flash memory device; an electrical, optical, acoustic, or other form of propagation signal (e.g., a carrier wave, an infrared signal, a digital signal, etc.), and the like. In addition, firmware, software, routines, instructions may be described in the present invention as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and that these actions are in fact generated by a computing device, a processor, a controller, or other devices that execute firmware, software, routines, instructions, etc., and that performing such operations may cause an actuator or other device to interact with the physical world.

[0115] Although embodiments of the invention may be specifically mentioned herein in the context of a 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 an object such as a wafer (or other substrate) or a mask (or other pattern forming device). These apparatus may be collectively referred to as a lithographic tool.

[0116] Although specific reference may have been made above to the use of embodiments of the present invention in the context of optical lithography, it should be appreciated that the present invention is not limited to optical lithography where the context permits.

[0117] The embodiment includes the following numbered clauses:

[0118] 1. A stand-alone conformity assessment system for determining at least one operational characteristic of a fluid extraction system of a substrate support, the conformity assessment system comprising:

[0119] an extraction support system configured to support two-phase fluid extraction by the fluid extraction system; and

[0120] A measurement system is configured to determine at least one operating characteristic of the fluid extraction system based on the two-phase fluid extraction.

[0121] 2. A conformity assessment system according to clause 1, wherein the two-phase fluid extraction comprises a liquid flow and a gas flow.

[0122] 3. A conformity assessment system according to clause 1 or 2, wherein the substrate support is for use in an immersion lithography apparatus.

[0123] 4. A conformity assessment system according to any preceding clause, further comprising a processor configured to determine at least one performance characteristic of the fluid extraction system based on the at least one determined operational characteristic.

[0124] 5. A conformity assessment system as described in clause 4, wherein the processor is configured to determine whether the fluid extraction system meets a performance specification based on the at least one performance characteristic.

[0125] 6. A conformity assessment system according to any of the preceding clauses, wherein the measurement system comprises a liquid-gas separator configured to separate a two-phase flow into a gas flow and a liquid flow; and

[0126] A flow meter, the flow meter is used to measure the gas flow;

[0127] The operating characteristics determined therein depend on the measured gas flow rate.

[0128] 7. A conformity assessment system according to any preceding clause, wherein the measurement system comprises one or more temperature sensors for measuring the temperature of at least part of the substrate support; and

[0129] Wherein the determined operating characteristic is dependent on a measured temperature of at least a portion of the substrate support.

[0130] 8. A conformity assessment system according to clause 4, wherein the conformity assessment system is configured to determine a fluid extraction rate / time; and

[0131] The performance characteristics determined are dependent upon the fluid extraction rate / time.

[0132] 9. A conformity assessment system according to any preceding clause, wherein the measurement system comprises one or more cameras for recording the extraction of the fluid.

[0133] 10. A conformity assessment system according to clause 9 when dependent on clause 4, wherein the processor is configured to determine a fluid extraction rate / time from the record; and

[0134] The performance characteristics determined are dependent upon the fluid extraction rate / time.

[0135] 11. A conformity assessment system according to any preceding clause, further comprising one or more heaters arranged to heat the substrate support; and

[0136] One or more electrical power sensors arranged to measure power consumption of one or more of the heaters.

[0137] 12. A conformity assessment system according to clause 11 when dependent on clause 4, wherein the processor is configured to determine the fluid extraction rate / time based on the measured power consumption; and

[0138] The determined performance characteristics depend on the determined fluid extraction rate / time.

[0139] 13. A conformity assessment system according to any of the preceding clauses, further comprising a fluid deposition system;

[0140] Wherein the fluid deposition system is configured to deposit liquid on the substrate while the substrate is held by the substrate support.

[0141] 14. A conformity assessment system according to any of the preceding clauses, wherein the extraction support system comprises a vacuum system for extracting the fluid.

[0142] 15. A conformity assessment system according to any of the preceding clauses, wherein the measurement system comprises one or more pressure sensors for measuring the pressure of the fluid.

[0143] 16. A conformity assessment system according to any preceding clause, wherein at least one of the operational characteristics is determined locally for a portion of the fluid extraction system.

[0144] 17. A substrate for determining at least one operational characteristic of a fluid extraction system of a substrate support, the substrate comprising:

[0145] one or more channels, the one or more channels being located on a major surface of the substrate, the one or more channels being used to accommodate a deposition liquid on the major surface of the substrate;

[0146] The end of each channel is located at the edge of the substrate.

[0147] 18. A substrate according to clause 17, wherein each channel is defined by a difference in wettability properties of the major surface of the substrate.

[0148] 19. A substrate according to clause 17 or 18, wherein each channel is defined by a difference in the surface profile of the major surface of the substrate.

[0149] 20. An apparatus comprising:

[0150] a conformity assessment system according to any of Clauses 1 to 16; and

[0151] A substrate according to any of clauses 17 to 19.

[0152] 21. An apparatus comprising:

[0153] Immersion lithography equipment; and

[0154] A substrate according to any of clauses 17 to 19.

[0155] 22. An apparatus according to clause 21, wherein the lithographic equipment comprises a camera arranged to record fluid extraction.

[0156] 23. A method for determining at least one operational characteristic of a fluid extraction system of a substrate support, the method comprising:

[0157] depositing a liquid onto a substrate;

[0158] extracting the liquid from the substrate in a two-phase fluid flow; and

[0159] At least one operating characteristic of the fluid extraction system is determined based on the two-phase fluid extraction.

[0160] 24. A method according to clause 23, wherein the method is performed by a conformity assessment system according to any of clauses 1 to 16.

[0161] 25. A method according to clause 23, wherein the method is performed within a lithographic device.

[0162] Although specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be practiced in other ways than those described. The above description is intended to be illustrative rather than restrictive. Therefore, it will be appreciated by those skilled in the art that modifications may be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A stand-alone qualification assessment system for determining at least one operational characteristic of a fluid extraction system of a substrate support, the qualification assessment system comprising: an extraction support system configured to support two-phase fluid extraction by the fluid extraction system; as well as A measurement system is configured to determine at least one operating characteristic of the fluid extraction system based on the two-phase fluid extraction.

2. The conformity assessment system of claim 1, wherein the two-phase fluid extraction comprises a liquid flow and a gas flow, and / or wherein the substrate support is used in an immersion lithography apparatus.

3. The conformity assessment system of claim 1 or 2, further comprising a processor configured to determine at least one performance characteristic of the fluid extraction system based on at least one determined operating characteristic.

4. A conformity assessment system according to claim 3, wherein the processor is configured to determine whether the fluid extraction system meets a performance specification based on the at least one performance characteristic, and / or wherein the processor is configured to determine a fluid extraction rate / time based on the recording; as well as The performance characteristics determined depend on the fluid extraction rate / time, and / or wherein the processor is configured to determine a fluid extraction rate / time based on the measured power consumption; as well as The determined performance characteristics depend on the determined fluid extraction rate / time.

5. The conformity assessment system according to any one of the preceding claims, wherein the measurement system comprises a liquid-gas separator configured to separate a two-phase flow into a gas flow and a liquid flow; and A flow meter, the flow meter is used to measure the gas flow; wherein the determined operating characteristic depends on the measured gas flow rate, and / or wherein the measurement system comprises one or more temperature sensors for measuring the temperature of at least a portion of the substrate support; and wherein the determined operating characteristic depends on a measured temperature of at least part of the substrate support, and / or wherein the measurement system comprises one or more cameras for recording the extraction of the fluid, and / or The measurement system comprises one or more pressure sensors for measuring the pressure of the fluid.

6. The conformity assessment system of claim 3, wherein the conformity assessment system is configured to determine a fluid extraction rate / time; and The performance characteristics determined are dependent upon the fluid extraction rate / time.

7. A conformity assessment system according to any one of the preceding claims, further comprising one or more heaters arranged to heat the substrate support; as well as one or more electrical power sensors arranged to measure the power consumption of one or more of the heaters, and / or Also included is a fluid deposition system; Wherein the fluid deposition system is configured to deposit liquid on the substrate while the substrate is held by the substrate support.

8. The conformity assessment system according to any of the preceding claims, wherein the extraction support system comprises a vacuum system for extracting the fluid.

9. A conformity assessment system according to any one of the preceding claims, wherein at least one of the operational characteristics is determined locally for a portion of the fluid extraction system.

10. A substrate for determining at least one operational characteristic of a fluid extraction system of a substrate support, the substrate comprising: one or more channels, the one or more channels being located on a major surface of the substrate, the one or more channels being used to accommodate a deposition liquid on the major surface of the substrate; The end of each channel is located at the edge of the substrate.

11. A substrate according to claim 10, wherein each channel is defined by a difference in wettability properties of the major surface of the substrate and / or wherein each channel is defined by a difference in surface profile of the major surface of the substrate.

12. An apparatus comprising: A conformity assessment system according to any one of claims 1 to 9; as well as A substrate according to claim 10 or 11.

13. An apparatus comprising: Immersion lithography equipment; as well as A substrate according to claim 10 or 11.

14. An apparatus according to claim 13, wherein the lithographic device comprises a camera arranged to record fluid extraction.

15. A method for determining at least one operational characteristic of a fluid extraction system of a substrate support, the method comprising: depositing a liquid onto a substrate; extracting the liquid from the substrate in a two-phase fluid flow; as well as At least one operating characteristic of the fluid extraction system is determined based on the two-phase fluid extraction.

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