Calibration substrate, method to determine an offset correction for a substrate to be loaded on a substrate support, combination of a substrate support and a calibration substrate, and substrate handling apparatus

Abstract

The invention provides a calibration substrate for determining an offset correction for a substrate to be loaded on a substrate support, the substrate support comprising a plurality of burls to support the substrate, the plurality of burls comprising edge supporting burls to support an edge area of the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with a height profile comprising one or more ridges, wherein, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged close to a number of edge supporting burls.

Description

CALIBRATION SUBSTRATE, METHOD TO DETERMINE AN OFFSET CORRECTION FOR A SUBSTRATE TO BE LOADED ON A SUBSTRATE SUPPORT, COMBINATION OF A SUBSTRATE SUPPORT AND A CALIBRATION SUBSTRATE, AND SUBSTRATE HANDLING APPARATUSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of EP application 24177893.5 which was filed on 24 May 2024 and which is incorporated herein in its entirety by reference.FIELD OF THE INVENTION

[0002] The present invention relates to a calibration substrate, a method to determine an offset correction for a substrate to be loaded on a substrate support, a combination of a substrate support and a calibration substrate, and a substrate handling apparatus.BACKGROUND ART

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”- direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0004] To support a substrate during a lithographic process a substrate support may be provided. In an embodiment, the substrate support may comprise a plurality of burls to support the substrate. The burls are distributed over a support area to provide support over the complete surface of the support side of a substrate. The advantage of the burls is that the substrate is supported over its whole area of the support side, while at the same time the contact area between the substrate and the substrate support is relatively small. This substantially reduces the chance that a particle, for example a dust particle, will be trapped between the support side of the substrate and the support surface of the substrate support. Furthermore, the space between the burls may be used as a vacuum chamber that applies a clamping force on thebasis of a vacuum created in the vacuum chamber.

[0005] Clamping of a substrate on a substrate support may be challenging, in particular when the substrate is warped. If the substrate is not properly clamped on the substrate support this may lead to poor focus, overlay and imaging performances of the lithographic process, in particular in edge areas of the substrate.

[0006] In order to improve clamping, a calibration method is known in which an offset of a substrate with respect to the substrate support is determined on the basis of a relationship between offset and clamping pressure of the vacuum chamber. In this calibration method the offset of a substrate is measured in a temperature stabilization unit, and after loading and clamping the substrate on the substrate support the associated clamping pressure of the vacuum clamp of the substrate support is determined. By repeating these steps for a number of offsets of the substrate with respect to the substrate support a relationship between offset and clamping pressure can be determined. Using this relationship, an offset can be predicted on the basis of the clamping pressure.

[0007] In this known calibration method, an offset error based on this relationship can be compensated by an offset correction in the pre-alignment of the substrate before being loaded on the substrate support. By applying the offset correction, the clamping of the substrate on the substrate support may be improved.

[0008] A drawback of this method is however that it requires a large number of (manual) steps to be carried out. This makes the method also very time-consuming.SUMMARY OF THE INVENTION

[0009] It is an object of the invention to provide an improved device or method to determine an offset correction for a substrate to be loaded on a substrate support, which offset correction may be used during pre-alignment and / or loading of the substrate on the substrate support.

[0010] According to an aspect of the invention, there is provided a calibration substrate for determining an offset correction for a substrate to be loaded on a substrate support, the substrate support comprising a plurality of burls to support the substrate, the plurality of burls comprising edge supporting burls to support an edge area of the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with a height profile having one or more ridges, wherein, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged close to a number of edge supporting burls.[Oil] According to an aspect of the invention, there is provided a method to determine an offset correction for a substrate to be loaded on a substrate support, comprising the steps of: clamping the calibration substrate of any of the preceding claims on the substrate support, determining position related parameters in at least an edge area of the calibration substrate, and determining an offset correction based on the position related parameters.

[0012] According to an aspect of the invention, there is provided a method to pre-align a substrate on a substrate support, for example for a lithographic process, comprising the steps of: clamping the calibration substrate of any of the preceding claims on the substrate support, determining position related parameters in at least an edge area of the calibration substrate, and determining an offset correction based on the position related parameters; and loading a substrate on the substrate support applying the determined offset correction.

[0013] According to an aspect of the invention, there is provided a combination of a substrate support and a calibration substrate to determine an offset correction for a substrate to be loaded on the substrate support, wherein the substrate support comprises a plurality of burls to support the substrate, the plurality of burls comprising edge supporting burls to support an edge area of the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with a height profile comprising one or more ridges, wherein, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged close to a number of edge supporting burls.

[0014] According to an aspect of the invention, there is provided a substrate handling apparatus comprising such combination.

[0015] According to an aspect of the invention, there is provided a calibration substrate for determining an offset correction for a substrate to be loaded on a substrate support, the substrate support comprising a plurality of burls to support the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with one or more recesses and / or one or more protrusions, wherein the one or more recesses and / or one or more protrusions are positioned to enable determination of an offset of the calibration substrate with respect to the substrate support based on measurement of position related parameters of the calibration substrate clamped on the substrate support.

[0016] According to an aspect of the invention, there is provided a method to determine an offset correction for a substrate to be loaded on a substrate support, comprising the steps of: clamping the calibration substrate of any of the claims 27-37 on the substrate support, measuring position related parameters of the calibration substrate, determining an offset correction based on the measured position related parameters.

[0017] According to an aspect of the invention, there is provided a method to pre-align a substrate on a substrate support, for example for a lithographic process, comprising the steps of: determining an offset correction for the substrate to be loaded on the substrate support using the method of any of the claims 38-43; and loading a substrate on the substrate support applying the determined offset correction.

[0018] According to an aspect of the invention, there is provided a combination of a substrate support and a calibration substrate to determine an offset correction for a substrate to be loaded on the substratesupport, wherein the substrate support comprises a plurality of burls to support the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with one or more recesses and / or one or more protrusions, wherein the one or more recesses and / or one or more protrusions are positioned to enable determination of an offset of the calibration substrate with respect to the substrate support based on measurement of position related parameters of the calibration substrate clamped on the substrate support.

[0019] According to an aspect of the invention, there is provided a substrate handling apparatus comprising the combination of any of the claims 45-49.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:Figure 1 depicts schematically a lithographic apparatus;Figure 2 depicts schematically a substrate support supporting a substrate;Figure 3 depicts schematically a calibration substrate for determining an offset correction for a substrate to be loaded on a substrate support according to an embodiment of an aspect of the invention;Figure 4 depicts schematically the calibration substrate of Figure 3 supported on a substrate support;Figure 5 depicts schematically a detail A of Figure 4;Figure 6 depicts schematically the detail A of Figure 4 in which the calibration substrate is shifted with respect to the substrate support;Figure 7 depicts schematically a top view of a calibration substrate on the substrate support in a centered position;Figure 8 depicts schematically a top view of a calibration substrate on the substrate support in a shifted position;Figure 9 shows a relationship between an angle around the circumference of the calibration substrate and a height level of an edge area of the calibration substrate in a centered position on the substrate support;Figure 10 shows a relationship between an angle around the circumference of the calibration substrate and a height level of an edge area of the calibration substrate in a shifted position on the substrate support;Figure 11 shows a relationship between offset of the calibration substrate with respect to the centered position on the substrate support and a height level of an edge area of the calibration substrate;Figure 12 depicts schematically a calibration substrate according to an alternative embodiment of an aspect of the invention.Figure 13 depicts schematically another embodiment of a calibration substrate;Figure 14 depicts schematically the calibration substrate of Figure 13 supported on a substrate support;Figure 15 depicts schematically a detail A of Figure 14;Figure 16 depicts schematically yet another embodiment of a calibration substrate;Figure 17 depicts schematically the calibration substrate of Figure 13 centered on a substrate support;Figure 18 depicts schematically yet another embodiment of a calibration substrate; andFigure 19 depicts schematically the calibration substrate of Figure 18 supported on a substrate support.DETAILED DESCRIPTION

[0021] Figure 1 schematically depicts a lithographic apparatus according to one embodiment of the invention. The apparatus comprises an illumination system IL, a support structure MT, a substrate table WT and a projection system PS.

[0022] The illumination system IL is configured to condition a radiation beam B. The support structure MT (e.g. a mask table) is constructed to support a patterning device MA (e.g. a mask) and connected to a first positioner PM configured to accurately position the patterning device in accordance with certain parameters. The substrate table WT (e.g. a wafer table) is constructed to hold a substrate W (e.g. a resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate in accordance with certain parameters. The projection system PS is configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W.

[0023] The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping, or controlling radiation.

[0024] The term “radiation beam” used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g. having a wavelength of or about 365, 355, 248, 193, 157 or 126 nm) and extreme ultra-violet (EUV) radiation (e.g. having a wavelength in the range of 5-20 nm), as well as particle beams, such as ion beams or electron beams.

[0025] The support structure MT supports, i.e. bears the weight of, the patterning device MA. The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device MA is held in a vacuum environment. The support structure MT can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device MA. The support structure MT may be a frame or a table, for example, which may be fixed or movable as required. The support structure MT may ensure that the patterning device MAis at a desired position, for example with respect to the projection system PS.

[0026] The term “patterning device” used herein should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section such as to create a pattern in a target portion C of the substrate W. It should be noted that the pattern imparted to the radiation beam B may not exactly correspond to the desired pattern in the target portion C of the substrate W, for example if the pattern includes phase-shifting features or so called assist features. Generally, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in the target portion C, such as an integrated circuit.

[0027] The patterning device MA may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam B in different directions. The tilted mirrors impart a pattern in a radiation beam B which is reflected by the mirror matrix.

[0028] The term “projection system” used herein should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors such as the use of an immersion liquid or the use of a vacuum.

[0029] As here depicted, the apparatus is of a transmissive type (e.g. employing a transmissive mask). Alternatively, the apparatus may be of a reflective type (e.g. employing a programmable mirror array of a type as referred to above, or employing a reflective mask).

[0030] The lithographic apparatus may be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such “multiple stage” machines the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure. In addition to one or more substrate tables WT, the lithographic apparatus may have a measurement stage that is arranged to be at a position beneath the projection system PS when the substrate table WT is away from that position. Instead of supporting a substrate W, the measurement stage may be provided with sensors to measure properties of the lithographic apparatus. For example, the projection system may project an image on a sensor on the measurement stage to determine an image quality.

[0031] The lithographic apparatus may also be of a type wherein at least a portion of the substrate W may be covered by a liquid having a relatively high refractive index, e.g. water, so as to fill a space between the projection system and the substrate. An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the patterning device MA and the projection system PS. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. The term “immersion” as used herein does not mean that a structure, such as asubstrate W, must be submerged in liquid, but rather only means that liquid is located between the projection system PS and the substrate W during exposure.

[0032] Referring to figure 1 , the illumination system IL receives a radiation beam B from a radiation source SO. The radiation source SO and the lithographic apparatus may be separate entities, for example when the radiation source SO is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiation beam B is passed from the radiation source SO to the illumination system IL with the aid of a beam delivery system BD comprising, for example, suitable directing mirrors and / or a beam expander. In other cases the radiation source SO may be an integral part of the lithographic apparatus, for example when the radiation source SO is a mercury lamp. The radiation source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system.

[0033] The illumination system IL may comprise an adjuster AD for adjusting the angular intensity distribution of the radiation beam B. Generally, at least the outer and / or inner radial extent (commonly referred to as o-outer and o-inner, respectively) of the intensity distribution in a pupil plane of the illumination system can be adjusted. In addition, the illumination system IL may comprise various other components, such as an integrator IN and a condenser CO. The illumination system IL may be used to condition the radiation beam B, to have a desired uniformity and intensity distribution in its cross-section.

[0034] The radiation beam B is incident on the patterning device MT, which is held on the support structure MT, and is patterned by the patterning device MA. Having traversed the patterning device MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF (e.g. an interferometric device, linear encoder or capacitive sensor), the substrate table WT can be moved accurately, e.g. so as to position different target portions C in the path of the radiation beam B. Similarly, the first positioner PM and another position sensor (which is not explicitly depicted in Figure 1) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan. In general, movement of the support structure MT may be realized with the aid of a long-stroke module and a short-stroke module, which form part of the first positioner PM. The long-stroke module may provide coarse positioning of the short-stroke module over a large range of movement. The short-stroke module may provide fine positioning of the support structure MT relative to the long-stroke module over a small range of movement. Similarly, movement of the substrate table WT may be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW. The long-stroke module may provide coarse positioning of the short-stroke module over a large range of movement. The short-stroke module may provide fine positioning of the substrate table WT relative to the long-stroke module over a small range of movement. In the case of a stepper (as opposed to a scanner) the support structure MT may be connected to a short-stroke actuator only, or may be fixed. Patterning device MA and substrateW may be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2. Although the substrate alignment marks Pl, P2 as illustrated occupy dedicated target portions, they may be located in spaces between target portions C (these are known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the patterning device MA, the mask alignment marks Ml, M2 may be located between the dies.

[0035] The depicted apparatus could be used in at least one of the following modes:

[0036] In a first mode, the so-called step mode, the support structure MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam B is projected onto a target portion C at one time (i.e. a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

[0037] In a second mode, the so-called scan mode, the support structure MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam B is projected onto a target portion C (i.e. a single dynamic exposure). The velocity and direction of the substrate table WT relative to the support structure MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion.

[0038] In a third mode, the support structure MT is kept essentially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. In this mode, generally a pulsed radiation source is employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as referred to above.

[0039] Combinations and / or variations on the above described modes of use or entirely different modes of use may also be employed.

[0040] Figure 2 shows an embodiment of a substrate support 100. The substrate support 100 comprises a substrate table 101 supported on another body of the substrate support, for example a mirror block. The substrate table 101 comprises a plurality of burls 102 provided on an upper side of the substrate table 101 to support a substrate W.

[0041] The plurality of burls 102 are distributed over the substrate table 101 to provide a support plane, formed by the upper ends of the burls 102 to support a substrate W to be loaded on the substrate support 100. The number of burls 102 are selected and distributed to provide a substantially flat support plane, but to have at the same time a small contact area between the substrate table 101 and the substrate W supported thereon to prevent or at least minimize the risk of particles being clamped between the substrate table 101 and the substrate W.

[0042] The space 103 between the burls 102 may be used as a vacuum clamping space 103 to clamp the substrate W on the burls 102. In such embodiment, a vacuum pump 104 may be provided to pump air out of the vacuum clamping space 103 via channel 105. A sealing ring 106 is arranged to delimit the vacuum clamping space 103 at its circumferential edge. The sealing ring 106 is lower than the burls 102. In the shown embodiment, an outer ring of burls 102a is arranged outside the vacuum clamping space 103. In alternative embodiments, all burls 102, including the outer ring of burls 102a, are within the vacuum clamping space 103, and / or two or more sealing rings are provided and the outer ring of burls is arranged between the two or more sealing rings.

[0043] Clamping of a substrate W on a substrate support 100 may be challenging, in particular when the substrate W is warped. If the substrate W is not properly clamped on the substrate support 100 this may lead to poor focus, overlay and imaging performances of the lithographic process, in particular in edge areas of the substrate W.

[0044] To improve clamping of the substrate W on the substrate support 100, it may be beneficial to apply an offset correction during pre-alignment of the substrate to compensate for a offset error occurring during loading of the substrate W on the substrate support 100.

[0045] Figure 3 depicts a calibration substrate 200 which can be used to determine an offset correction for a substrate W to be loaded on a substrate support 100. The calibration substrate 200 is configured to be supported on the plurality of burls 102 of the substrate support 100 of Figure 2 similar to the substrate W shown in Figure 2.

[0046] Figure 4 shows the calibration substrate 200 centered on the substrate support 100.

[0047] The calibration substrate 200 comprises a support side 201 to be supported on the plurality of burls 102 and a measurement side 202 opposite to the support side 201. The measurement side 202 can be used to measure position related parameters of the substrate 200 when clamped on the substrate support 100, such as height levels of the upper surface of the calibration substrate or the position of markers 207 arranged on the calibration substrate 200 at its measurement side 202.

[0048] The support side 201 of the calibration substrate 200 is provided with a height profile comprising one or more ridges 203. The one or more ridges 203 may advantageously have a steep transition between different height levels and are for example step-shaped.

[0049] The height profile on the support side 201 of the calibration substrate 200 may be formed by a first coating layer 204 provided on a main body 205 of the calibration substrate 200, wherein parts of the first coating layer 204 are removed to form the one or more ridges 203. In the shown embodiment of Figure 3, a circular ridge 203 is formed by removing an outer circumferential part of the first coating layer 204.

[0050] The removed parts of the first coating layer 204 layer can be removed by etching, for example by plasma etching. Any other way to provide the height profile on the support side of the calibration substrate 200 may also be applied.

[0051] At the measurement side 202 of the calibration substrate 200 a second coating layer 206 isarranged on the main body 205 of the calibration substrate 200. The second coating layer 206 is placed on the calibration substrate 200 to prevent warpage of the calibration substrate 200 due to a coating layer being present on only one side of the main body 205 of the calibration substrate 200. The first coating layer 204 and the second coating layer 206 are for example made of a silicon nitide coating material and may have substantially the same thickness. The thickness of the first coating layer 204 and the second coating layer 206 may for example be in the range of 20 nm to 2000 nm, for instance in the range of 25 nm to 500 nm, such as about 50 nm. The main body 205 may be a silicon substrate.

[0052] The height of the circular ridge 203 of the calibration substrate 100 shown in Figure 3 corresponds with the thickness of the first coating layer 204, since the circular ridge 203 is created by complete removal of the outer circumferential part of the first coating layer 204. In alternative embodiments, the first coating layer is only partially removed in height with the result that the height of the one or more ridges 203 may be lower than the thickness of the first coating layer 204.

[0053] The one or more ridges 203 are arranged in such a way that, when the calibration substrate 200 is correctly centered on the substrate support 100, as shown in Figure 4, the one or more ridges 203 of the height profile are arranged on the burls 102a of the outer ring of burls 102a of the substrate support 100. In the shown embodiment, the one or more ridges 203 form one circular ridge 203.

[0054] More generally, the one or more ridges 203 of a calibration substrate 200 may be arranged, when the calibration substrate 200 is correctly centered on the substrate support 100, to be close to a number of burls of the substrate support 200 that are arranged to support an edge area of a substrate loaded on the substrate support 100. These burls arranged to support an edge area of a substrate may be indicated as edge supporting burls.

[0055] Since the circular ridge 203 of the calibration substrate 200 is configured to be arranged on the outer ring of burls 102a, when the calibration substrate 200 is correctly positioned on the substrate support 100, the diameter of the circular edge may correspond with the diameter of the outer ring of burls 102a plus or minus the contact surface dimension of the burls of the outer ring of burls 102a, wherein the diameter of the outer ring of burls 102a is determined with respect to the center axes of the respective burls and the contact surface dimension of the burls of the outer ring of burls 102a is the complete surface area of the burls that may come into contact with a substrate W loaded on the burls.

[0056] For example, when the burls are cylindrically shaped and have a circular upper surface to support a substrate W, the diameter of the outer ring of burls 102a is determined with respect to central axes of the cylindrically shape burls and the diameter of the circular upper surface of the burl is the contact surface dimension.

[0057] In known embodiments of a substrate and substrate support, the substrate may have a diameter of 300 mm. In embodiments, the diameter of the center axes of the burls of the outer ring of burls 102a is 293 mm, 296 mm or 293.14 mm and the diameter of the contact surface of the burls is 0.35 mm, 0.21 mm or 0.27 mm, respectively. This results for these embodiments that the circular ridge 203 may be in the ranges of 292.65 mm to 293.35 mm, 295.79 to 296.21 mm and 292.87 mm to 293.41 mm,respectively. Of course other ranges may be applied for substrates and substrate supports having other suitable dimensions.

[0058] Figure 5 shows detail A of the embodiment of Figure 4, where the calibration substrate is correctly centered on the substrate support 100. The circular ridge 203 is arranged on a burl of the outer ring of burls 102a. In this example, the diameter of the circular edge 203 approximately corresponds to the diameter of the outer ring of burls 102a, such that the circular edge 203 extends to approximately the middle of the burl of the outer ring of burls 102a. In this position, the calibration substrate 200 is supported by all the burls 102, including all burls of the outer ring of burls 102a.

[0059] Figure 6 discloses the same combination of substrate support 100 and calibration substrate 200 supported thereon, but with an offset with respect to the correct position. In particular, the calibration substrate 100 is shifted to the right as indicated by an arrow in Figure 6. Due to this offset, the circular ridge 203 is no longer in contact with the burl of the outer ring of burls 102a. As the circular ridge 203 is no longer in contact with this burl, the respective edge area of the calibration substrate 200 is no longer properly supported by the substrate support and, as a result, the calibration substrate 200 may move into another position. By measuring position related parameters in at least an edge area of the calibration substrate 200 this change in position can be determined, for example by measuring a height level of at least an edge area of the calibration substrate or by measuring the position of markers 207 arranged on the calibration substrate 200, in particular in an edge area thereof.

[0060] Figures 7 and 8 show schematic top views of the calibration substrate 200 on the substrate support 100. The circular ridge 203 of the calibration substrate 200 is shown as a dashed line. The substrate support 100 comprises a plurality of burls to support the calibration substrate 200. Only the outer ring of burls 102a is shown. In practice multiple burls will be present within the outer ring of burls 102a to provide a substantially flat support plane to support a substrate W.

[0061] Figure 7 shows the position of the calibration substrate 200 on the substrate support 100 corresponding to the position shown in Figure 5. In this position, the calibration substrate 200 is correctly centered with respect to the substrate support 100. As a result, the height level of the edge area along the circumference of the edge will substantially be the same.

[0062] Figure 8 shows the calibration substrate 200 on the substrate support 100 corresponding to the position shown in Figure 6. In this position, the calibration substrate 200 has an offset with respect to the centered position of the calibration substrate 200 on the substrate support 100. As the calibration substrate 200 will not be supported by burls of the outer ring of burls 102a along a part of the edge area of the circumference of the calibration substrate 200, the height level of the calibration substrate 200 at this part of the edge area will be different than the height level of the edge area of the calibration substrate 200 that is supported by burls of the outer ring of burls 102a. As a result, on the basis of the height level of the edge area along the circumference of the edge, it can be determined whether the edge area of the calibration substrate 200 is supported by the respective burls, or not.

[0063] For example, Figure 9 shows a height level of the edge area in dependence of the angle a (seeFig. 7) along the circumference of the edge of the calibration substrate 200, corresponding to the position of the calibration substrate 200 shown in Figure 7. The height level of an edge area of the calibration substrate 200, which may be measured with a leveling sensor, is substantially the same along the circumference of the calibration substrate 200.

[0064] Figure 10 shows the same measurement of the height level of the edge area along the circumference of the calibration substrate 200, but for the offset position of the calibration substrate 200 shown in Figure 8. From Figure 10, it is clear that the height level of the edge area of the calibration substrate 200 that is not supported by the outer ring of burls 102a is lower than the height level of the edge area of the calibration substrate 200 that is supported by the burls of the outer ring of burls 102a.

[0065] The difference in height level of edge areas of the calibration substrate 200 can thus be used to determine the offset of the calibration substrate 200 with respect to the desired centered position of the calibration substrate 200 on the substrate support 100.

[0066] Figure 11 shows an example of the relationship between offset and height level of an edge area of the calibration substrate 200 in a direction of movement of the calibration substrate 200 with respect to the substrate support 100.

[0067] The relationship between height levels of the calibration substrate 200 and the associated offset may be determined for different directions, for example for x-direction and y-direction, such that the offset correction can also be determined in these directions.

[0068] To determine an offset and associated offset correction, the calibration substrate 200 only needs to be loaded on the substrate support 100 a single time. After loading and clamping of the calibration substrate 200 on the substrate support 100 the height level of the edge area of the calibration substrate 200 can be measured at different angular positions or sections of the circumference of the edge area of the calibration substrate. On the basis of the measured height levels of the edge area at the different angular positions or sections of the circumference of the calibration substrate, an offset of the calibration substrate with respect to the substrate support in for example x-direction and y-direction may be determined. Once this position is known an offset correction can be determined on the basis of the determined offset. It is also possible that on the basis of the measured height levels at the different angular positions or sections of the circumference of the calibration substrate a position of the calibration substrate 200 is determined and that an offset correction is calculated on the basis of a comparison of the determined position of the calibration substrate 200 with respect to the substrate support 100 and a desired position of the calibration substrate 200 with respect to the substrate support 100. In both methods the offset correction can be determined in a time efficient manner.

[0069] In the above exemplary embodiment, height levels of the calibration substrate 200 measured with a leveling sensor are used to determine an offset of the calibration substrate and an associated offset correction.

[0070] More generally, any position related parameter in at least an edge area of the calibration substrate that depends on the position of the calibration substrate 200 with respect to a number of edgesupporting burls of the substrate support 100 can be used.

[0071] For example, the position related parameters may be positions of a plurality of markers 207 arranged in at least an edge area of the calibration substrate 200. The positions of the plurality of markers 207 may be measured by an alignment measuring device.

[0072] Any other suitable position related parameter may also be used.

[0073] Furthermore, in the above exemplary embodiment, the outer ring of burls 102a is used to determine the offset in combination with a circular ridge 203 of a calibration substrate 200, which circular edge 203 of the height profile of the calibration substrate 200 is arranged on the burls of the outer ring of burls 102a, when the calibration substrate 200 is correctly centered on the substrate support 100.

[0074] In other embodiments other edge supporting burls of the plurality of burls of the substrate support may be used to determine offset and / or offset correction. In an embodiment, an inner ring of burls adjacent to the outer ring may be used to determine offset. In such an embodiment, an associated calibration substrate to be supported on the plurality of burls is provided with a height profile comprising one or more ridges, in which, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged close to the edge supporting burls of the inner ring of burls adjacent to the outer ring. In other embodiments, any other set of edge supporting burls may be used in combination with one or more ridges of the height profile adjusted to this set of edge supporting burls.

[0075] Figure 12 shows an example of a calibration substrate 220 having a height profile with a star shaped configuration of ridges 221 that are aligned with edge supporting burls 102b of the plurality of burls of the substrate support 100. The edge supporting burls 102b comprise burls of the two outer rings of burls of the substrate support 100. When the calibration substrate 220 is correctly centered on the substrate support 100, as shown in Figure 12, the ridges 221 of the height profile of the calibration substrate 220 are arranged on the respective number of edge supporting burls 102b. Other configurations are also possible.

[0076] Hereinabove, a calibration substrate 200 to be used on a substrate support 100 is described. The substrate support 100 may be a substrate support of a lithographic apparatus, but also of any other substrate handling device, such as a metrology tool. The substrate support may have a vacuum clamping device, an electrostatic clamping device or any other type of clamping device to clamp a substrate on the substrate support.

[0077] Figure 13 depicts another example of a calibration substrate 230 which can be used to determine an offset correction for a substrate W to be loaded on a substrate support 100. The calibration substrate 230 is configured to be supported on the plurality of burls 102 of the substrate support 100 of Figure 2 similar to the substrate W shown in Figure 2.

[0078] Figure 14 shows the calibration substrate 230 of Figure 13 centered on the substrate support 100. Figure 15 shows a detail of Figure 14.

[0079] The calibration substrate 230 comprises a support side 231 to be supported on the plurality of burls 102 and a measurement side 232 opposite to the support side 231. The measurement side 232 can be used to measure position related parameters of the substrate 230 when clamped on the substrate support 100, such as height levels of the upper surface of the calibration substrate or the position of markers 237 arranged on the calibration substrate 230 at its measurement side 232.

[0080] The support side 231 of the calibration substrate 230 is provided with a circumferential recess 233 provided at the edge of the calibration substrate 230. The recess 233 at the edge of the calibration substrate 230 may be formed in a first coating layer 234 provided on a main body 235 of the calibration substrate 230. The first coating layer 234 has a central area having a flat surface and an edge area comprising the circumferential recess 233.

[0081] In the shown embodiment of Figure 13, the circumferential recess 231 is formed by providing a slanting surface in the edge area of the calibration substrate 230, wherein a thickness of the first coating layer 234 becomes thinner towards the outer edge of the calibration substrate 230. The removed parts of the first coating layer 234 layer are for example removed by etching, for example by plasma etching. Any other way to provide the circumferential recess 233 with a slanting surface on the support side 231 of the calibration substrate 230 may also be applied.

[0082] At the measurement side 232 of the calibration substrate 230 a second coating layer 236 is arranged on the main body 235 of the calibration substrate 230 to prevent warpage of the calibration substrate 230 due to the first coating layer 234 being present on only one side of the main body 235 of the calibration substrate 230. The first coating layer 234 and the second coating layer 236 are for example made of a silicon nitride coating material and may have substantially the same thickness. The thickness of the first coating layer 234 and the second coating layer 236 may for example be in the range of 20 nm to 2000 nm, for instance in the range of 25 nm to 500 nm, such as about 50 nm. The main body 235 may be a silicon substrate.

[0083] As can be seen in Figures 14 and 15, the edge area of the calibration substrate 230 and in particular the circumferential recess 233 are aligned with the outer ring of burls 102a of the substrate support 100. When the calibration substrate 230 is placed on the substrate support 100 without being clamped, as shown in Figures 14 and 15, there is a spacing between the outer ring of burls 102a and the calibration substrate 230.

[0084] When the calibration substrate 230 is clamped on the substrate support 100, the edge of the calibration substrate 230 will be pulled on the outer ring of burls 102a such that the spacing between the circumferential recess 233 and the outer ring of burls 102a is closed. As a result, the outer edge of the calibration substrate 230 will bend. This bending of the calibration substrate 230 in the edge area will have effect on position related parameters of the calibration substrate 230 that can be measured by for example a level sensor or an alignment sensor. On the basis of the measured position related parameters, an offset of the calibration substrate 230 with respect to the center of the substrate support 100 can be determined. This offset can be used to apply an offset correction for loading a substrate onthe substrate support 100.

[0085] In an alternative embodiment, a circumferential protrusion with respect to a flat surface of the center part of the calibration substrate may be provided.

[0086] Figure 16 depicts yet another example of a calibration substrate 240 which can be used to determine an offset correction for a substrate W to be loaded on a substrate support 100. The calibration substrate 240 is configured to be supported on the plurality of burls 102 of the substrate support 100 of Figure 2 similar to the substrate W shown in Figure 2.

[0087] The calibration substrate 240 comprises a main body 245, for example a silicon substrate, having a support side 241 to be supported on the plurality of burls 102 and a measurement side 242 opposite to the support side 241. The measurement side 242 can be used to measure position related parameters of the substrate 240 when clamped on the substrate support 100, such as height levels of the upper surface of the calibration substrate or the position of markers 247 arranged on the calibration substrate 240 at its measurement side 242.

[0088] The support side 241 of the calibration substrate 240 is provided with a circumferential ring shaped protrusion 249 provided in an edge region of the calibration substrate 240. The ring shaped protrusion 249 may be deposited on the support side 241. The height of the protrusion 249 may for example be in the range of 20 nm to 2000 nm, for instance in the range of 25 nm to 500 nm, such as about 50 nm.

[0089] The ring shaped protrusion 249 is arranged at a location where the protrusion 249 will not contact the burls, e.g. the outer ring of burls 102a, when the calibration substrate 240 is correctly centered with respect to the substrate support 100. In this position, the ring shaped protrusion 249 is configured to extend around the outer ring of burls 102a when the calibration substrate 240 is correctly centered with respect to the substrate support 100. The ring shaped protrusion 249 has an inner diameter corresponding with, i.e. the same or slightly larger than, an outer diameter of the ring of outer burls 102a, such that, when the calibration substrate 240 is correctly centered on the substrate support 100, the ring shaped protrusion 249 will be arranged around the ring of outer burls 102a.

[0090] In known embodiments of a substrate and substrate support, the substrate may have a diameter of 300 mm. In embodiments, the diameter of the center axes of the burls of the outer ring of burls 102a is 293 mm, 296 mm or 293.14 mm and the diameter of the contact surface of the burls is 0.35 mm, 0.21 mm or 0.27 mm, respectively. This results for these embodiments that the inner diameter of the ring shaped protrusion 249 is at least 293.35 mm, 296.21 mm or 293.41 mm, respectively. Of course other ranges may be applied for substrates and substrate supports having other suitable dimensions.

[0091] Figure 17 shows schematically the calibration substrate 240 correctly centered with respect to the substrate support 100. It can be seen that the ring shaped protrusion 249 extends around the ring of outer burls 102a, and has no effect on the support of the calibration substrate 240 on the plurality of burls 102. When the calibration substrate 240 is shifted with respect to the centered position a part of the ring shaped protrusion 249 may be arranged on a number of burls of the outer ring of burls 102a.This will have an effect on the calibration substrate 240 that can be determined on the basis of the position related parameters that can be measured using a level sensor and / or an alignment sensor. On the basis of such offset measurements, an offset correction can be determined that can be used when loading a substrate on the substrate support 100.

[0092] As an alternative for the embodiment of Figure 16, a calibration substrate may be provided with a ring shaped protrusion that has an inner diameter corresponding with, i.e. the same or slightly smaller than, the inner diameter of the outer ring of burls 102a.

[0093] In embodiments, in which the diameter of the center axes of the burls of the outer ring of burls 102a is 293 mm, 296 mm or 293.14 mm and the diameter of the contact surface of the burls is 0.35 mm, 0.21 mm or 0.27 mm, respectively, the outer diameter of the ring shaped protrusion 249 should be maximally 292.65 mm, 295.79 or 292.87 mm, respectively to fall within the ring of outer burls 102a when correctly centered on the substrate support 100.

[0094] In other embodiments, the calibration substrate may be provided with a ring shaped protrusion that is designed to be around or within another ring of burls of the plurality of burls 102 than the outer ring of burls 102a.

[0095] The ring shaped protrusion 249 may be formed by a single protrusion that extends around the whole circumference of the calibration substrate 240. In another embodiment, the ring shaped protrusion may be formed by multiple ring segments.

[0096] Figure 18 shows schematically yet another example of a calibration substrate 250 which can be used to determine an offset correction for a substrate W to be loaded on a substrate support 100.

[0097] Figure 19 shows the calibration substrate 250 of Figure 13 centered on the substrate support 100.

[0098] The calibration substrate 250 comprises a main body 255, for example a silicon substrate, having a support side 251 to be supported on the plurality of burls 102 and a measurement side 252 opposite to the support side 251. The measurement side 252 can be used to measure position related parameters of the substrate 250 when clamped on the substrate support 100, such as height levels of the upper surface of the calibration substrate or the position of markers 257 arranged on the calibration substrate 250 at its measurement side 252.

[0099] The support side 251 of the calibration substrate 250 is provided with multiple protrusions 253 that form a pattern at the support side 251 of the calibration substrate 250. The multiple protrusions are dot shaped protrusions that may for example have maximum dimensions, in all directions, in the range of 20 nm to 2000 nm, for instance in the range of 25 nm to 500 nm, such as about 50 nm. The protrusions may also have other shapes. In other embodiments, the protrusions 253 may extend over a longer range in one or more directions parallel to the calibration substrate 250.

[0100] The pattern of the multiple protrusions 253 is adapted to the locations of the burls 102 of the plurality of burls 102 of the substrate support 100, such that the protrusions 253 are not arranged on one or more of the burls when the calibration substrate 250 is correctly centered on the substrate support100.

[0101] The pattern of the multiple protrusions 253 may for example be arranged according to a nonius scale or another suitable pattern.

[0102] If the calibration substrate 250 is not correctly centered on the substrate support 100 one or more of the protrusions 253 may be aligned with one or more of the burls 102, such that the respective one or more protrusions 253 will be placed on the one or more of the burls 102, when the calibration substrate 250 is clamped on the substrate support 100. As a consequence, a height level of an upper surface of the calibration substrate 250 will be at a higher position compared to other parts of the calibration substrate 250. These elevated parts of the calibration substrate 250 may be determined by a level sensor when making a height map of the calibration substrate 250 when clamped on the substrate support 100.

[0103] On the basis of the locations of the elevated parts of the calibration substrate 250, it may be determined which of the protrusions 253 are arranged on a respective burl of the plurality of burls 102. Since the pattern of the protrusions 253 is known as well as the locations of the burls of the plurality of burls 102, an offset of the calibration substrate 250 with respect to a centered position can be determined. This offset can be used to apply an offset correction when loading a substrate W on the substrate support 100.

[0104] The relationship between height levels of the calibration substrate 250 and the associated offset may be determined for different directions, for example for x-direction and y-direction, such that the offset correction can also be determined in these directions.

[0105] The pattern of the multiple protrusions 253 of the calibration substrate 250 shown in Figure 18 is configured such that the protrusions 253 are not arranged on one or more of the burls, when the calibration substrate 250 is correctly centered on the substrate support 100. In alternative embodiments, the pattern of the multiple protrusions 253 of the calibration substrate 250 may be configured such that one or more of the protrusions 253 are arranged on one or more of the burls when the calibration substrate 250 is correctly centered on the substrate support 100.

[0106] The pattern of protrusions 253 may comprise multiple sub-patterns, wherein at least two subpatterns are adapted to determine an offset correction for two different substrate supports 100 having different burl configurations of the plurality of burls 102. This means that a single calibration substrate may be configured to determine an offset / offset correction for two or more types of substrate supports, each substrate support having a different configuration of the plurality of burls 102. A first sub-pattern may be adapted to determine an offset / offset correction for a first type of substrate support and a second sub-pattern may be adapted to determine an offset / offset correction for a second type of substrate support. In this way a single design of a calibration substrate 250 can be used for multiple types of substrate supports having different configurations of the plurality of burls.

[0107] In addition, or as an alternative, the pattern of protrusions 253 may comprises multiple subpatterns, wherein each of at least three sub-patterns is adapted to determine an offset / offset correctionfor a specific burl configuration of the plurality of burls. It may be advantageous that the calibration substrate 250 comprises multiple sub-patterns, wherein each sub-pattern can be used to determine an offset and / or offset correction for the same specific burl configuration. This results in a redundancy in the determination of the offset and / or offset correction, that can be used to distinguish between an elevated part of the upper surface of the calibration substrate 250 caused by offset or by another cause, for example local contamination. If on the basis of each of the multiple sub-patterns, the same offset is determined, it is likely that this measurement is not affected by a local contamination. If the offset determined on the basis of one of the sub-patterns deviates from the offset determined on the basis of the other sub-patterns, it is likely that local contamination affected the determination of the offset of this one sub-pattern.

[0108] The sub-patterns may be provided in different areas of the calibration substrate 250, but may also be provided in overlapping areas of the calibration substrate 250.

[0109] The pattern of protrusions 253 may be adapted to indicate in position related measurements different offset patterns for different offsets of the calibration substrate with respect to the substrate support 100. This means that the offset patterns as determined in the results of the position related measurements can be used to distinguish between different types of offsets, for example direction and / or magnitude.

[0110] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion", respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and / or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0111] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist leaving a pattern init after the resist is cured.

[0112] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.

[0113] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims

CLAIMS1. A calibration substrate for determining an offset correction for a substrate to be loaded on a substrate support, the substrate support comprising a plurality of burls to support the substrate, the plurality of burls comprising edge supporting burls to support an edge area of the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with a height profile comprising one or more ridges, wherein, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged close to a number of edge supporting burls.

2. The calibration substrate of claim 1 , wherein, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged on the respective number of edge supporting burls.

3. The calibration substrate of claim 1 or 2, wherein the height profile is formed by a first coating layer, wherein parts of the coating layer are removed to form the one or more ridges.

4. The calibration substrate of claim 3, wherein the substrate comprises at a side opposite to the support side a second coating layer having substantially a same thickness as the first coating layer.

5. The calibration substrate of claim 3 or 4, wherein the parts of the coating layer are removed by etching, for example by plasma etching.

6. The calibration substrate of any of the claims 1-5, wherein the one or more ridges comprise one circular ridge associated with the number of edge supporting burls, wherein the number of edge supporting burls comprises an outer ring of the plurality of burls.

7. The calibration substrate of any of the claims 1-6, wherein the substrate has a diameter of about 300 mm and the one or more ridges comprise one concentric circular ridge with a diameter in the range of 292,5 mm to 293,5 mm.

8. The calibration substrate of any of the claims 1-7, wherein the calibration substrate comprises a plurality of markers arranged in at least an edge area of the calibration substrate.

9. The calibration substrate of any of the claims 1-8, wherein the one or more ridges are step shaped.

10. The calibration substrate of any of the claims 1-9, wherein the one or more ridges have a height in the range of 20 nm to 2000 nm.

11. A method to determine an offset correction for a substrate to be loaded on a substrate support, comprising the steps of: clamping the calibration substrate of any of the preceding claims on the substrate support, measuring position related parameters in at least an edge area of the calibration substrate, determining an offset correction based on the position related parameters.

12. The method of claim 11, wherein determining the offset correction comprises: measuring position related parameters at different angular positions or sections of the circumference of the edge area of the calibration substrate, determining an offset or position of the calibration substrate with respect to the substrate support on the basis of the position related parameters at the different angular positions or sections of the circumference of the edge area of the calibration substrate, and determining the offset correction based on the offset or a comparison of the determined position of the calibration substrate with respect to the substrate support and a desired position of the calibration substrate with respect to the substrate support.

13. The method of claim 11 or 12, wherein the position related parameters are height levels of an upper surface of the calibration substrate in at least the edge area of the calibration substrate.

14. The method of claim 13, wherein the height levels of the calibration substrate in at least the edge area of the calibration substrate are measured by a levelling sensor.

15. The method of claim 11 or 12, wherein the position related parameters are positions of a plurality of markers arranged in at least the edge area of the calibration substrate.

16. The method of claim 15, wherein the positions of the plurality of markers are measured by an alignment measurement device.

17. A method to pre-align a substrate on a substrate support, for example for a lithographic process, comprising the steps of: determining an offset correction for the substrate to be loaded on the substrate support using the method of any of the claims 11-16; and loading a substrate on the substrate support applying the determined offset correction.

18. A combination of a substrate support and a calibration substrate to determine an offset correction for a substrate to be loaded on the substrate support, wherein the substrate support comprises a plurality of burls to support the substrate, the plurality of burls comprising edge supporting burls to support an edge area of the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with a height profile comprising one or more ridges, wherein, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged close to a number of edge supporting burls.

19. The combination of claim 18, wherein, when the calibration substrate is correctly centered on the substrate support, the one or more ridges of the height profile are arranged on the number of edge supporting burls.

20. The combination of claim 18 or 19, wherein the number of edge supporting burls are formed by an outer ring of the plurality of burls.

21. The combination of claim 20, wherein between the plurality of burls one or more vacuum spaces of a vacuum clamping device of the substrate support are provided.

22. The combination of any of the claims 20 or 21, wherein the one or more ridges of the calibration substrate comprise one circular ridge associated with the number of edge supporting burls formed by the outer ring of the plurality of burls.

23. The combination of claim 22, wherein a diameter of the circular edge corresponds with a diameter of the outer ring of the plurality of burls plus or minus the contact surface dimension of the burls of the outer ring of the plurality of burls, wherein the diameter of the outer ring of the plurality of burls is determined with respect to center axes of the respective burls and the contact surface dimension of the burls of the outer ring of the plurality of burls is the complete surface area of the respective burls that may come into contact with a substrate loaded on the burls.

24. A substrate handling apparatus comprising the combination of any of the claims 18-23.

25. The substrate handling apparatus of claim 24, wherein the substrate handling apparatus comprises a leveling sensor to measure a height level of a calibration substrate supported on the substrate support.

26. The substrate handling apparatus of claim 24 or 25, wherein the substrate handling apparatusis a lithographic apparatus.

27. A calibration substrate for determining an offset correction for a substrate to be loaded on a substrate support, the substrate support comprising a plurality of burls to support the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with one or more recesses and / or one or more protrusions, wherein the one or more recesses and / or one or more protrusions are positioned to enable determination of an offset of the calibration substrate with respect to the substrate support based on measurement of position related parameters of the calibration substrate clamped on the substrate support.

28. The calibration substrate of claim 27, wherein the support side comprises an edge area configured to be supported on edge supporting burls of the plurality of burls and a central area configured to be supported on central burls of the plurality of burls, wherein the central area has a flat surface and wherein the edge area comprises a circumferential recess or a circumferential protrusion with respect to the flat surface.

29. The calibration substrate of claim 28, wherein the edge supporting burls are formed by a ring of outer burls, and wherein the circumferential recess is aligned with the ring of outer burls.

30. The calibration substrate of claim 28, wherein the edge supporting burls are formed by a ring of outer burls, and wherein the circumferential protrusion is a circumferential ring, wherein the circumferential ring has an inner diameter corresponding with an outer diameter of the ring of outer burls or wherein the circumferential ring has an outer diameter corresponding with an inner diameter of the ring of outer burls, such that, when the calibration substrate is correctly centered on the substrate support, the circumferential ring will be arranged around or within the ring of outer burls, respectively.

31. The calibration substrate of claim 27, wherein the one or more recesses and / or the one or more protrusions form a pattern at the support side of the calibration substrate.

32. The calibration substrate of claim 31, wherein the pattern comprises multiple sub-patterns, wherein at least two sub-patterns are adapted to determine an offset correction for two different substrate supports having different burl configurations of the plurality of burls.

33. The calibration substrate of claim 31 or 32, wherein the pattern comprises multiple subpatterns, wherein each of at least three sub-patterns is adapted to determine an offset correction for a specific burl configuration of the plurality of burls.

34. The calibration substrate of any of the claims 31-33, wherein the pattern is adapted to indicate in position related measurements different offset patterns for different offsets of the calibration substrate with respect to the substrate support.

35. The calibration substrate of any of the claims 27-34, wherein the one or more recesses and / or the one or more protrusions are formed by a first coating layer.

36. The calibration substrate of claim 35, wherein the substrate comprises at a side opposite to the support side a second coating layer having substantially a same thickness as the first coating layer.

37. The calibration substrate of any of the claims 27-36, wherein the one or more recesses and / or the one or more protrusions have a height in the range of 20 nm to 2000 nm.

38. A method to determine an offset correction for a substrate to be loaded on a substrate support, comprising the steps of: clamping the calibration substrate of any of the claims 27-37 on the substrate support, measuring position related parameters of the calibration substrate, determining an offset correction based on the measured position related parameters.

39. The method of claim 38, wherein determining the offset correction comprises: measuring position related parameters at different angular positions or sections of the circumference of the edge area of the calibration substrate, determining an offset or position of the calibration substrate with respect to the substrate support on the basis of the position related parameters at the different angular positions or sections of the circumference of the edge area of the calibration substrate, and determining the offset correction based on the offset or a comparison of the determined position of the calibration substrate with respect to the substrate support and a desired position of the calibration substrate with respect to the substrate support.

40. The method of claim 38 or 39, wherein the position related parameters are height levels of an upper surface of the calibration substrate.

41. The method of claim 40, wherein the height levels of the calibration substrate are measured by a levelling sensor.

42. The method of claim 38 or 39, wherein the position related parameters are positions of aplurality of markers arranged on the calibration substrate.

43. The method of claim 42, wherein the positions of the plurality of markers are measured by an alignment measurement device.

44. A method to pre-align a substrate on a substrate support, for example for a lithographic process, comprising the steps of: determining an offset correction for the substrate to be loaded on the substrate support using the method of any of the claims 38-43; and loading a substrate on the substrate support applying the determined offset correction.

45. A combination of a substrate support and a calibration substrate to determine an offset correction for a substrate to be loaded on the substrate support, wherein the substrate support comprises a plurality of burls to support the substrate, wherein a support side of the calibration substrate to be supported on the plurality of burls is provided with one or more recesses and / or one or more protrusions, wherein the one or more recesses and / or one or more protrusions are positioned to enable determination of an offset of the calibration substrate with respect to the substrate support based on measurement of position related parameters of the calibration substrate clamped on the substrate support.

46. The combination of claim 45, wherein the support side comprises an edge area configured to be supported on edge supporting burls of the plurality of burls and a central area configured to be supported on central burls of the plurality of burls, wherein the central area has a flat surface and wherein the edge area comprises a circumferential recess or a circumferential protrusion with respect to the flat surface.

47. The combination of claim 46, wherein the edge supporting burls are formed by a ring of outer burls, and wherein the circumferential recess is aligned with the ring of outer burls.

48. The combination of claim 46, wherein the edge supporting burls are formed by a ring of outer burls, and wherein the circumferential protrusion is a circumferential ring, wherein the circumferential ring has an inner diameter corresponding with an outer diameter of the ring of outer burls or wherein the circumferential ring has an outer diameter corresponding with an inner diameter of the ring of outer burls, such that, when the calibration substrate is correctly centered on the substrate support, the circumferential ring will be arranged around or within the ring of outer burls, respectively.

49. The combination of claim 45, wherein the one or more recesses and / or the one or moreprotrusions form a pattern at the support side of the calibration substrate.

50. A substrate handling apparatus comprising the combination of any of the claims 45-49.

51. The substrate handling apparatus of claim 50, wherein the substrate handling apparatus comprises a leveling sensor to measure a height level of a calibration substrate supported on the substrate support.

52. The substrate handling apparatus of claim 50 or 51 , wherein the substrate handling apparatus is an exposure apparatus, for example a lithographic apparatus.

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