WO2025157567A1 - Improved reticle stage thermal overlay - Google Patents

Abstract

A method of managing overlay impact caused by deformation of one or more encoder scales due to thermal impact of loading a reticle onto a reticle stage, the method comprising: obtaining data on a thermal profile of a reticle; simulating deformation of the one or more reticle stage encoder scales upon loading the reticle onto the reticle stage based on the thermal profile of the reticle to determine an impact the deformation will have on a patterning process; calculating, based on said simulation, a correction factor to correct the patterning process to manage the overlay impact, and applying correction factor to manage the overlay impact. Also provided is a method of imaging a substrate, a system, a device, and a non-transitory computer-readable medium configured to perform or execute such a method. Also disclosed is an apparatus for managing overlay impact as the use in a lithographic system, apparatus or method.

Description

IMPROVED RETICLE STAGE THERMAL OVERLAY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of EP application 24153691.1 which was filed on 24 January 2024 and which is incorporated herein in its entirety by reference.

FIELD OF THE INVENTION

[0002] The present disclosure relates to a method of improving reticle stage thermal overlay performance by introducing a reticle load feedforward into the overlay control strategy. The present disclosure relates to a method of managing overlay impact caused by deformation of one or more encoder scales due to thermal impact of loading a reticle onto a reticle stage. The present disclosure also relates to a method of imaging a substrate including managing overlay impact and imaging a pattern onto the substrate. The present disclosure also relates to a system comprising at least one processor and at least one memory storing instructions that cause the system to perform such a method, as well as a device comprising a memory and a processor configured to execute such a method. Furthermore, the present disclosure relates to a non-transitory computer-readable medium storing computer instructions configured to cause one or more processors to perform such a method. The present disclosure also relates to an apparatus for managing overlay impact caused by deformation of one or more encoder scales due to thermal impact of loading a reticle onto a reticle stage. The present disclosure also relates to the use of such methods, systems, devices, media, and apparatuses in a lithographic apparatus or method. The present disclosure has particular, but not exclusive, application to EUV lithography.

BACKGROUND

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

[0004] The wavelength of radiation used by a lithographic apparatus to project a pattern onto a substrate determines the minimum size of features which can be formed on that substrate. A lithographic apparatus which uses EUV radiation, being electromagnetic radiation having a wavelength within the range 4-20 nm, may be used to form smaller features on a substrate than a conventional lithographic apparatus (which may for example use electromagnetic radiation with a wavelength of 193 nm).

[0005] A lithographic apparatus includes a patterning device (e.g. a mask or reticle). Radiation is provided through or reflected off the patterning device to form an image on a substrate. A membrane assembly, also referred to as a pellicle, may be provided to protect the patterning device from airborne particles and other forms of contamination. [0006] In use, the reticle is exposed to a beam of radiation, which causes the reticle to heat up. In order to manage the temperature of the reticle, the reticle is provided with cooling, which may be in the form of liquid cooling. The reticle is supported by a reticle clamp that holds the reticle in place on a reticle stage. Even though the temperature of the reticle is controlled, the shape of the reticle changes upon exposure to the radiation beam, which causes deformation of the reticle that can lead to overlay issues. Whilst some deformation may be corrected by alignment adjustments, there remains parts of the deformation which cannot be corrected by existing methods, and are therefore non-correctable. As lithographic technology develops further, overlay requirements are becoming much more stringent as the need for precision continues to increase. At different stages of operation, there are different deformations caused by different thermal conditions, which contribute to overlay errors and it is desirable to avoid or minimise such errors.

[0007] The present invention has been devised in an attempt to address at least some of the problems identified above.

SUMMARY OF THE INVENTION

[0008] According to a first aspect of the present disclosure, there is provided a method of managing overlay impact caused by deformation of one or more encoder scales due to thermal impact of loading a reticle onto a reticle stage, the method comprising: obtaining data on a thermal profile of a reticle; simulating deformation of the reticle stage encoder scales upon loading of the reticle onto the reticle stage based on the thermal profile of the reticle to determine an impact the deformation will have on a patterning process; calculating, based on said simulation, a correction factor to correct the patterning process to manage the overlay impact, and applying the correction factor to manage the overlay impact. [0009] Reticles and reticle blanks for use in lithographic apparatuses and processes are generally made from ultra-low expansion (ULE) glass. ULE is used as its shape changes by only a small amount as compared to other materials when its temperature changes. Even so, this is insufficient to address the deformations which occur when a reticle is first loaded onto a reticle stage. One contributor to reticle stage thermal overlay impact is pre-exposure reticle stage heating, also referred to as fast reticle stage heating. Fast reticle stage heating is the effect of heating up of the material above the reticle due to loading a reticle onto a stage at a different temperature to the reticle. This causes deformations of the reticle stage, which leads to deformation of encoder scales that are used to accurately position the reticle, and this leads to positioning errors of the reticle stage, which causes an overlay impact, which is undesirable. The size of this effect scales with the temperature difference between the reticle and the reticle stage, so with higher source powers, the temperature of water used to cool the reticle decreases, which results in the impact of pre-exposure reticle stage heating to become larger. Whilst ULE glass can offer some improvements, further improvements are required.

[00010] According to the present disclosure, one way to mitigate overlay impact is by using a correction loop to control the overlay impact that is induced by loading a reticle on to a reticle stage at a different temperature. Overlay induced errors mainly comprise correctable content, that is content which can be corrected for using the pre-existing controls of an EUV utilization apparatus, such as a lithographic apparatus. In particular, the main observed deformations are translation in an x-direction as well as curvature. The impact of loading a reticle on the deformation of an encoder scale is a systematic effect that happens every time a reticle is loaded. By predicting the impact by means of a simulation, such as a Finite Element Method (FEM) simulation, which may optionally be supplemented by experimental calibrations, and then correcting for such impact in a feed-forward control method, the impact can be reduced significantly. As such, the method includes obtaining data on a thermal profile of a reticle. This may include, for example, the temperature of the reticle or an existing model of how the reticle transfers heat to a reticle stage or based on estimations due to the thermal history of the reticle. This can also include reticle-specific information, such as material properties. The deformation of the one or more reticle stage encoder scales when the reticle is first loaded onto the reticle stage is then simulated based on the thermal profile of the reticle and this is used to determine the impact the deformation will have on the patterning process. Once the impact of the deformation on the patterning process has been modelled, a correction factor may be calculated and applied in order to manage the overlay impact. The correction factor may be calculated as a percentage of the maximum simulated deformation and/or overlay impact. For example, if the deformation caused by loading a reticle, which also determines the ultimate overlay impact of such a loading, is calculated to be, for example, 1 nm, then the correction factor may be calculated to correct for a 1 nm overlay error or for lower percentages of the overlay error. For example, if the overlay error were calculated to be, for example, 1 nm, the correction factor may be calculated with a view to correcting for 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% of this value, namely 0.9 nm, 0.8nm, 0.7 nm, 0.6 nm, 0.5 nm, 0.4 nm, 0.3nm, 0.2 nm, or 0.1 nm. In this way, the method takes into account limitations on how much correction can be made due to physical limitations since the apparatus on which the method is applied may not be physically capable of making large corrections. Furthermore, simulations and models always include a degree of uncertainty and so by limiting the correction factor to a percentage of the calculated/simulated overlay error, the possibility of overcorrection is mitigated. For example, a simulated deformation of 0.5 nm would lead to an overlay penalty of around 0.1 nm. As such, the correction factor may be calculated with a view to managing, say, 50% of the deformation and so seek to mitigate 0.05 nm of the overlay impact.

[00011] The method may include using at least one of a clamp temperature, a chiller temperature, encoder scale details, and thermomechanical properties of one or more of the reticle, clamp, and reticle stage body to simulate said deformation of the reticle stage encoder scales. Since the deformation is dependent on a number of factors, considering a greater number of such factors when simulating the deformation improves the accuracy of the simulation.

[00012] The method may further include obtaining the reticle heating data by one or both of physical means and simulated means. As such, the data on the thermal profde of the reticle can be gained by measuring the temperature of the reticle itself or could be simulated based on the known conditions to which the reticle has been subject. The reticle temperature can also be a reference value in the absence of a more accurate estimation.

[00013] The physical means may include one or both of sensors and thermal trackers.

[00014] The method may include utilizing a look-up table to determine the correction factor. In order to increase the speed at which the method, which is preferably a computer-implemented method, functions, instead of calculations, a look up table can be used to retrieve relevant output values based on the input values.

[00015] The method may include aligning the reticle relative to a substrate by taking into account the correction factor. Once the overlay error has been predicted, the correction factor may be applied by aligning the reticle relative to a substrate in a way which includes the calculated correction factor.

[00016] The simulation may be created via one or both of a finite element method simulation and experimental calibration. Since it is possible to measure the efficacy of the correction factor, it is possible to refine the simulation based on real-world measurements to further improve performance.

[00017] The overlay impact may be determined each time the reticle is loaded. Since the deformation which is to be corrected for in the present disclosure is a rapid deformation upon loading, rather than a longer term changes or drifts in performance, the method according to the present disclosure is preferably performed every time a reticle is loaded.

[00018] The reticle load temperature may be used to calculate the correction factor. As discussed, deformation occurs when there is a temperature difference between a reticle and a reticle stage. In order to improve the calculation of the correction factor, the temperature of the reticle itself may be considered.

[00019] The method may include measuring the overlay impact caused by loading of the reticle and comparing the measured overlay impact with the simulated impact, optionally further including adjusting the simulation to better match the measured overlay impact. In this way, the present method is not only a feed-forward implementation, but also can include feedback information to further improve accuracy.

[00020] The method may include imaging a substrate subsequent to the correction factor being applied. As such, once the fast reticle stage heating deformation and consequent overlay error has been accounted for, the method may include imaging a substrate and this will have a lower overlay error that would have otherwise been the case.

[00021] According to a second aspect of the present disclosure, there is provided a method of imaging a substrate, said method including managing overlay impact according to the method of the first aspect, and imaging a pattern onto the substrate.

[00022] According to a third aspect of the present disclosure, there is provided a system comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the system to perform the method of the first or second aspects of the present disclosure.

[00023] According to a fourth aspect of the present disclosure, there is provided a device comprising a memory and a processor configured to execute a method according to the first or second aspects of the present disclosure.

[00024] According to a fifth aspect of the present disclosure, there is provided a non-transitory computer-readable medium storing computer readable instructions configured to cause one or more processors to perform the method according to the first or second aspects of the present disclosure.

[00025] According to a sixth aspect of the present disclosure, there is provided an apparatus for managing overlay impact caused by deformation of one or more encoder scales due to thermal impact of loading a reticle onto a reticle stage, the apparatus including: an illumination system configured to condition a radiation beam; a reticle stage configured to support a reticle configured to pattern the radiation beam, the reticle stage including at least one encoder scale; a projection system configured to project the patterned radiation beam onto a substrate; and a control system configured to manage overlay impact caused by deformation of the at least one encoder scale due to thermal impact of loading the reticle onto the reticle stage by obtaining data on a thermal profile of the reticle, simulating deformation of the at least one reticle stage encoder scale based on the thermal profile of the reticle to determine an impact the deformation will have on a patterning process; calculating, based on said simulation, a correction factor to correct the patterning process to manage the overlay impact, and applying the correction factor to manage the overlay impact.

[00026] The apparatus may be an EUV utilization apparatus, such as an EUV lithography apparatus. [00027] According to a seventh aspect of the present disclosure, there is provided an EUV utilization system including the apparatus according to the sixth aspect of the present disclosure and a radiation source.

[00028] According to an eighth aspect of the present disclosure, there is provided the use of a method according to the first or second aspects, a system according to the third aspect, a device according to the fourth aspect, a non-transitory computer-readable medium according to the fifth aspect, or an apparatus according to the sixth aspect of the present disclosure in a lithographic apparatus or method.

[00029] It will be appreciated that features described in respect of one aspect may be combined with any features described in respect of another aspect and all such combinations are expressly considered and disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[00030] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawing in which corresponding reference symbols indicate corresponding parts, and in which: [00031] Figure 1 depicts a lithographic apparatus according to an embodiment of the disclosure; [00032] Figure 2 is a schematic depiction of the method according to the present disclosure;

[00033] Figure 3 is a schematic depiction of a reticle load feed-forward method according to the present disclosure;

[00034] Figure 4 is a graph showing the overlay impact over time comparing the overlay impact which has been corrected according to the present method versus uncorrected overlay impact; and [00035] Figure 5 is another graph comparing corrected and uncorrected overlay impact and taking into account incoming reticle temperature.

[00036] The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

DETAILED DESCRIPTION

[00037] Figure 1 shows a lithographic system according to the present invention. The lithographic system comprises a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B. The lithographic apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g. a mask), a projection system PS and a substrate table WT configured to support a substrate W. The illumination system IL is configured to condition the radiation beam B before it is incident upon the patterning device MA, also referred to as a reticle. The projection system is configured to project the radiation beam B (now patterned by the mask MA) onto the substrate W. The substrate W may include previously formed patterns. Where this is the case, the lithographic apparatus aligns the patterned radiation beam B with a pattern previously formed on the substrate W. In this embodiment, a pellicle 15 is depicted in the path of the radiation and protecting the patterning device MA. It will be appreciated that the pellicle 15 may be located in any required position and may be used to protect any of the mirrors in the lithographic apparatus. The patterning device MA may be referred to as the reticle. The support structure MT may be referred to as the reticle stage.

[00038] The radiation source SO, illumination system IL, and projection system PS may all be constructed and arranged such that they can be isolated from the external environment. A gas at a pressure below atmospheric pressure (e.g. hydrogen) may be provided in the radiation source SO. A vacuum may be provided in illumination system IL and/or the projection system PS. A small amount of gas (e.g. hydrogen) at a pressure well below atmospheric pressure may be provided in the illumination system IL and/or the projection system PS.

[00039] The radiation source SO shown in Figure 1 is of a type which may be referred to as a laser produced plasma (LPP) source. A laser, which may for example be a CO2 laser, is arranged to deposit energy via a laser beam into a fuel, such as tin (Sn) which is provided from a fuel emitter. Although tin is referred to in the following description, any suitable fuel may be used. The fuel may for example be in liquid form, and may for example be a metal or alloy. The fuel emitter may comprise a nozzle configured to direct tin, e.g. in the form of droplets, along a trajectory towards a plasma formation region. The laser beam is incident upon the tin at the plasma formation region. The deposition of laser energy into the tin creates a plasma at the plasma formation region. Radiation, including EUV radiation, is emitted from the plasma during de-excitation and recombination of ions of the plasma.

[00040] The EUV radiation is collected and focused by a near normal incidence radiation collector (sometimes referred to more generally as a normal incidence radiation collector). The collector may have a multilayer structure which is arranged to reflect EUV radiation (e.g. EUV radiation having a desired wavelength such as 13.5 nm). The collector may have an elliptical configuration, having two ellipse focal points. A first focal point may be at the plasma formation region, and a second focal point may be at an intermediate focus, as discussed below.

[00041] The laser may be separated from the radiation source SO. Where this is the case, the laser beam may be passed from the laser to the radiation source SO with the aid of a beam delivery system (not shown) comprising, for example, suitable directing mirrors and/or a beam expander, and/or other optics. The laser and the radiation source SO may together be considered to be a radiation system.

[00042] Radiation that is reflected by the collector forms a radiation beam B. The radiation beam B is focused at a point to form an image of the plasma formation region, which acts as a virtual radiation source for the illumination system IL. The point at which the radiation beam B is focused may be referred to as the intermediate focus. The radiation source SO is arranged such that the intermediate focus is located at or near to an opening in an enclosing structure of the radiation source.

[00043] The radiation beam B passes from the radiation source SO into the illumination system IL, which is configured to condition the radiation beam. The illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11. The faceted field mirror device 10 and faceted pupil mirror device 11 together provide the radiation beam B with a desired cross-sectional shape and a desired angular distribution. The radiation beam B passes from the illumination system IL and is incident upon the patterning device MA held by the support structure MT. The patterning device MA reflects and patterns the radiation beam B. The illumination system IL may include other mirrors or devices in addition to or instead of the faceted field mirror device 10 and faceted pupil mirror device 11.

[00044] Following reflection from the patterning device MA the patterned radiation beam B enters the projection system PS. The projection system comprises a plurality of mirrors 13, 14 which are configured to project the radiation beam B onto a substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the radiation beam, forming an image with features that are smaller than corresponding features on the patterning device MA. A reduction factor of 4 may for example be applied. Although the projection system PS has two mirrors 13, 14 in Figure 1, the projection system may include any number of mirrors (e.g. six mirrors). [00045] The radiation sources SO shown in Figure 1 may include components which are not illustrated. For example, a spectral fdter may be provided in the radiation source. The spectral fdter may be substantially transmissive for EUV radiation but substantially blocking for other wavelengths of radiation such as infrared radiation.

[00046] If the patterning device MA is left unprotected, the contamination can require the patterning device MA to be cleaned or discarded. Cleaning the patterning device MA interrupts valuable manufacturing time and discarding the patterning device MA is costly. Replacing the patterning device MA also interrupts valuable manufacturing time.

[00047] Figure 2 is a schematic depiction of the method according to the present disclosure. The method may be described as a reticle load feed-forward approach. Since the overlay induced error comprises mainly of correctable content it is possible to use a feed-forward correction to take account of the impact of loading a cold reticle onto the reticle stage. The impact of loading a reticle on the bending and translation of the encoder scales is a systematic effect that happens during every reticle load. Predicting the impact by means of a simulation, optionally accompanied by experimental calibration and correcting for the impact in a feed-forward control method according to the present disclosure reduces the overlay error. Thermal information 18 relating to the reticle and system information 19, such as reticle stage temperature, material, cooling water temperature and any other relevant factors, are fed into a FEM simulated database 20, which may be in the form of a calibrated look-up table. This is used to predict the overlay error caused by pre-exposure reticle stage heating and then correct for it. The output of the FEM simulated database generates the required correction factor 21 which is then fed into control software of the scanner 21 to implement the correction factor, thereby managing the overlay error. This may be used alongside a reticle heating feed-forward algorithm and system information can be obtained from the reticle heating feed-forward system, but there is no dependency for overlay control between the reticle heating feed-forward and the reticle loading feed forward (to which the present disclosure primarily relates) since the physical phenomena and overlay shapes to be corrected are different, so the control algorithms are not required to be integrated. In other words, there are two very different physical phenomena which need to be accounted for, the deformation due to loading of a reticle, which is a rapid, short term change, and the deformation caused by heating of the combined reticle and reticle stage (as well as other equipment in thermal contact with the same) which is a slower and more long-term change. Such correction methods are not equivalent, but can be used one after the other. Previously, no correction was made upon reticle loading, meaning that overlay error was high and uncorrected.

[00048] Figure 3 depicts one implementation of the method according to the present disclosure. A simulation determines the overlay impact due to fast reticle stage heating after each reticle load. This can be an inline FEM model or a generated look-up table for which the fast reticle stage heating effect is determined on the basis of the input parameters 18. Such input parameters may be chiller temperature, clamp material, as well as system-dependent properties, as well as an estimate of the temperature of the reticle when loading if an estimate or measured value is available. The simulated overlay error may then be corrected for, yielding a reticle load feed forward correction factor. A calibration 23 can be implemented to improve matching between the measured effect and the simulated effect. In the depiction, the simulated system is depicted as the upper MA and the physical system is depicted as the lower MA, both of which can be fed-forward into the reticle loading feed forward correction factor 24. [00049] Figure 4 is a graph showing the overlay impact scaled to experimentally obtained data for a corrected (lower line) and an uncorrected (upper line) case. As can be seen, the overlay error is considerably less in the corrected version than in the corrected version and remains so even after the effect of the fast reticle stage heating has passed.

[00050] Figure 5 depicts two graphs, one depicting uncorrected and one depicting corrected overlay in accordance with the present disclosure. It is know that the load temperature of the reticle is variable, which introduces uncertainty in various control aspects of the reticle heating fed forward overlay control system. In both graphs, the upper line relates to a hot reticle, namely one which is at a higher temperature (around 28°C) than the nominal situation, perhaps due to prior exposure to a radiation beam, the middle line relates to a conditioned reticle which is at ambient temperature of around 22°C, and the lower line relates to a cold reticle at around 14°C. In each case, the residual feed forward overlay error is reduced for the case in which the method of the present disclosure is applied, even after the effect of the fast reticle stage heating has dissipated and a different heating regime have taken over. These graphs show that drift of the overlay error is significantly decreased and that uncertainties in the loading temperature of the reticle do not negate the effectiveness of the present method. Proper estimation of the reticle temperature, such as via a tracker or a sensor, would provide improved performance still. In each graph, the line which has the highest peak relates to a hot reticle, the line with the lowest peak relates to a cold reticle, and the line with the second highest peak relates to a conditioned reticle.

[00051] In summary, the present disclosure provides method for mitigating overlay error caused by loading of a reticle onto a reticle stage. The method reduces the overlay error caused by the fast reticle stage heating, but also reduces the overlay error once the fast reticle stage heating effect has subsided, for example after around 30s, but even when a different heating and deformation regime take place over longer time periods. Previously, only the overlay error caused by the longer time period heating and deformation regimes were accounted for, but the present disclosure provides for a complementary but different method which also positively impacts on the longer time regimes that can be used in conjunction with existing overlay correction methods.

[00052] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described.

[00053] 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

1. A method of managing overlay impact caused by deformation of one or more encoder scales due to thermal impact of loading a reticle onto a reticle stage, the method comprising:

- obtaining data on a thermal profde of a reticle;

- simulating deformation of the one or more reticle stage encoder scales upon loading of the reticle onto the reticle stage based on the thermal profile of the reticle to determine an impact the deformation will have on a patterning process;

- calculating, based on said simulation, a correction factor to correct the patterning process to manage the overlay impact, and applying the correction factor to manage the overlay impact.

2. The method of claim 1, wherein the method further includes using at least one of a clamp temperature, a chiller temperature, encoder scale details, and thermomechanical properties of the one or more of the reticle, clamp, and reticle stage body to simulate said deformation of the reticle stage encoder scales.

3. The method of claim 1 or claim 2, wherein the method further includes obtaining the reticle heating data by one or both of physical means and simulated means.

4. The method of claim 3, wherein the physical means includes one or both of sensors and thermal trackers.

5. The method of claim 3 or claim 4, wherein the method includes utilizing a look-up table to determine the correction factor.

6. The method of any preceding claim, wherein the method includes aligning the reticle relative to a substrate by taking in account the correction factor.

7. The method of any preceding claim, wherein the simulation is created via one or both of a finite element method simulation and experimental calibration.

8. The method of any preceding claim, wherein the overlay impact is determined each time the reticle is loaded.

9. The method of any preceding claim, wherein a reticle load temperature is used to calculate the correction factor.

10. The method of any preceding claim, wherein the method includes measuring the overlay impact caused by loading of the reticle and comparing the measured overlay impact with the simulated impact, optionally further including adjusting the simulation to better match the measured overlay impact.

11. The method of any preceding claim, wherein the method further includes imaging a substrate subsequent to the correction factor being applied.

12. A method of imaging a substrate, said method including managing overlay impact according to the method of any of claims 1 to 11, and imaging a pattern onto the substrate.

13. A system comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the system to perform the method of any preceding claim.

14. A device comprising a memory and a processor configured to execute a method according to any of Claims 1 to 12.

15. A non-transitory computer-readable medium storing computer readable instructions configured to cause one or more processors to perform the method of any one of claims 1 to 12.

16. An apparatus for managing overlay impact caused by deformation of one or more encoder scales due to thermal impact of loading a reticle onto a reticle stage, the apparatus including: an illumination system configured to condition a radiation beam; a reticle stage configured to support a reticle configured to pattern the radiation beam, the reticle stage including at least one encoder scale; a projection system configured to project the patterned radiation beam onto a substrate; and a control system configured to manage overlay impact caused by deformation of the at least one encoder scale due to thermal impact of loading the reticle onto the reticle stage by obtaining data on a thermal profile of the reticle, simulating deformation of the at least one reticle stage encoder scale based on the thermal profile of the reticle to determine an impact the deformation will have on a patterning process; calculating, based on said simulation, a correction factor to correct the patterning process to manage the overlay impact, and applying the correction factor to manage the overlay impact.

17. The apparatus according to claim 16, wherein the apparatus is an EUV utilization apparatus.

18. An EUV utilization system including the apparatus according to claim 16 and a radiation source.

19. The use of a method according to any of claims 1 to 12, system according to claim 13, device according to claim 14, non-transitory computer-readable medium according to claim 15, or apparatus according to claims 16 or 17, or a EUV utilization system according to claim 18 in a lithographic system, apparatus, or method.