Method and control device for producing an optical system for a lithography apparatus

Abstract

The invention relates to a method for producing an optical system (100) for a lithography apparatus (1), wherein the optical system (100) comprises an optical component (102) having an optically active surface (106) and a substrate (104), said method comprising: a) providing (S2), for a substrate (104', 204a, 204b, 204c) of one or more optical components (102, 202a, 202b, 202c), a respective normalised distribution function (g, ha, hb, hc) of a zero crossing temperature (ZCT', ZCTa, ZCTb, ZCTc) of a coefficient of thermal expansion (p') of the respective substrate (104', 204a, 204b, 204c) as a function of a location (r) of the substrate (104', 204a, 204b, 204c), b) determining (S3) in a computer-implemented manner, for each provided distribution function (g, ha, hb, hc) and for a plurality of predetermined mean zero crossing temperatures (Mj) different from each other, an imaging error (Fi) of the optical system (102), and c) determining (S4) at least one selected mean zero-crossing temperature (Maw) for the substrate (104) of the optical component (102) to be produced as that one of the plurality of mean zero-crossing temperatures (Mj) for which the determined imaging error (Fi) is smaller than a predetermined threshold value (SW).

Description

[0001] Carl Zeiss SMT GmbH 1 METHOD AND CONTROL DEVICE FOR PRODUCING AN OPTICAL SYSTEM FOR A LITHOGRAPHY SYSTEM The present invention relates to a method and a control device for producing an optical system for a lithography system. The content of the priority application DE 102023205439.6 is incorporated by reference in its entirety. Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system that has an illumination system and a projection system.The image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system, for example a silicon wafer, in order to transfer the mask structure onto the light-sensitive coating of the substrate. Driven by the pursuit of ever smaller structures in the manufacture of integrated circuits, EUV lithography systems are currently being developed that use light with a wavelength in the range of 0.1 nm to 30 nm, particularly 13.5 nm. Since most materials absorb light at this wavelength, such EUV lithography systems must use reflective optics, i.e., mirrors, instead of the previously used refractive optics, i.e., lenses.One problem that arises is that the mirrors heat up due to the absorption of the radiation emitted by the EUV light source. This can lead to thermal deformation of the mirrors. Furthermore, an increase in temperature can also degrade the optical coating on the mirrors. Both thermal deformation of the mirrors and damage to their optical coatings can impair the imaging properties of the mirrors. The imaging quality of projection systems in an EUV lithography system depends to a large extent on the quality of the mirror material. In order to reduce imaging errors caused by heating of the mirrors, a material with a very low coefficient of thermal expansion is used for mirror substrates. This is particularly important for the so-calledZero-crossing temperature of the thermal expansion coefficient of the mirror material, a deformation of the mirror material as a function of a temperature increase is minimal and / or zero. The average zero-crossing temperature of the mirror material as well as variations in the zero-crossing temperature within the mirror substrate volume have a direct influence on imaging errors caused by mirror heating. Against this background, an object of the present invention is to provide an improved method and an improved device for producing an optical system for a lithography system. Accordingly, a method for producing an optical system for a lithography system is proposed. The optical system comprises an optical component with an optically active surface and a substrate.The method further comprises: a) providing, for a substrate of one or more optical components, a respective normalized distribution function of a zero-crossing temperature of a thermal expansion coefficient of the respective substrate as a function of a location of the substrate, Carl Zeiss SMT GmbH 3 b) computer-implemented determination, for each provided distribution function and for a plurality of mutually different predetermined average zero-crossing temperatures, of an imaging error of the optical system, and c) determining at least one selected average zero-crossing temperature for the substrate of the optical component to be produced as that of the plurality of average zero-crossing temperatures for which the determined imaging error is smaller than a predetermined threshold value.The average zero-crossing temperature of the thermal expansion coefficient of the substrate material of the optical component can be adjusted during substrate manufacture. Typically, the average zero-crossing temperature of the substrate material is adjusted depending on the expected operating temperature of the substrate. A substrate material of an optical component typically has inhomogeneities that lead to an inhomogeneous distribution of the zero-crossing temperature across the substrate volume. This even applies to a high-performance substrate material. The inhomogeneous distribution of the zero-crossing temperature influences the imaging properties of the optical component and thus of the optical system with the optical component. The applicant discovered that imaging errors of the optical system for a given (e.g.The (normalized) distribution of the zero-crossing temperature across the substrate volume of the optical component depends on the mean zero-crossing temperature of the substrate. Furthermore, the mean zero-crossing temperature of the substrate can be adjusted, e.g., by heat treatment, even after the substrate has been manufactured (and thus for a zero-crossing temperature profile determined during manufacturing). Carl Zeiss SMT GmbH 4 The proposed method now makes it possible to determine a favorable and / or optimal mean zero-crossing temperature of the substrate of the optical component with regard to imaging quality for one or more predetermined normalized distributions of the zero-crossing temperature across the substrate volume.The distribution function of the zero-crossing temperature of the thermal expansion coefficient of the respective substrate as a function of the location of the substrate is, for example, a three-dimensional distribution function of the zero-crossing temperature over a three-dimensional substrate body. The normalized distribution function of the zero-crossing temperature of the respective substrate is, for example, a distribution function of the zero-crossing temperature that has been normalized based on a value (e.g., mean value) of the distribution function. In a subsequent step, the substrate of the optical component to be manufactured can then be processed such that its mean zero-crossing temperature corresponds to (i.e., is equal to) the favorable and / or optimal mean zero-crossing temperature determined during the process.Because the substrate thus has the determined favorable and / or optimal average zero-crossing temperature, thermal deformations caused by heat input into the mirror (e.g., through irradiation with EUV light) and the associated deterioration of the imaging properties can be reduced or avoided. The coefficient of thermal expansion indicates a change in the geometric shape and dimensions of a material when the temperature changes. The coefficient of thermal expansion is, for example, a linear coefficient of thermal expansion that indicates a change in length of a material as a function of a temperature change. The Carl Zeiss SMT GmbH 5 coefficient of thermal expansion is itself temperature-dependent, i.e. a temperature-dependent function. At its zero-crossing temperature (Engl.In a "Zero Crossing Temperature" (ZCT), the coefficient of thermal expansion exhibits a zero crossing in its temperature dependence, around which no or only negligible thermal expansion of the mirror substrate material occurs when the temperature changes. The substrate material of the optical component to be manufactured is, in particular, a material with a low coefficient of thermal expansion. For example, the coefficient of thermal expansion at a desired operating temperature lies within a range of + / - 20 ppb / K (parts per billion per Kelvin), + / - 15 ppb / K, + / - 10 ppb / K, and / or + / - 5 ppb / K. However, the coefficient of thermal expansion can also lie within a different range. In the case of such a material with ultra-low thermal expansion (e.g. one known as "ULE" for "Ultra-Low Expansion" by Corning Inc.With the substrate material (sold by Schott), changes in geometric shape and dimensions due to temperature changes occur only to a very small extent. Examples of the substrate material of the optical component to be manufactured include a glass material made of TiO2-SiO2, in which the ultra-low thermal expansion coefficient is achieved by varying the concentration of TiO2. Another example is a Li2O-Al2O3-SiO2 glass-ceramic (sold under the name "Zerodur" by Schott) with a crystalline phase, in which the ultra-low thermal expansion coefficient is achieved by uniformly distributed nanocrystals in a residual glass phase. Step a) and / or step c) is / are also carried out, for example, by computer implementation. For example, steps a), b) and / or c) are carried out by a Carl Zeiss SMT GmbH 6 control device, e.g., a control device of one or more computers.In step a), the one or more normalized distribution functions of the zero-crossing temperature are provided, for example, by a provision device of the control device, e.g., also transmitted to a first determination device of the control device. In particular, in step a), a normalized distribution function of the zero-crossing temperature as a function of location is provided for each of the one or more optical components. In the case of multiple normalized distribution functions, the multiple normalized distribution functions differ from one another in terms of the shape and size of fluctuations in the zero-crossing temperature as a function of location. In particular, each of the multiple distribution functions is different from all other distribution functions. As a result of the normalization, the multiple distribution functions have the same average zero-crossing temperature (e.g.,a mean zero-crossing temperature of zero). In step b), the imaging error of the optical system is determined, in particular, for each combination of the one or more provided normalized distribution functions and the several predetermined mean zero-crossing temperatures. If, for example, two different normalized distribution functions and three different values ​​for the mean zero-crossing temperature are provided, this results in six possible combinations. Thus, six different error values ​​for the imaging error of the optical system are determined based on the six different combinations. Carl Zeiss SMT GmbH 7 In step b), several error values ​​F - assigned to the normalized distribution function(s) and the several values ​​for the mean zero-crossing temperature - are determined. iof the image of the optical system. In step c), the determined error values ​​Fi are then compared with the predetermined threshold value. In particular, the error values ​​F ithat are smaller than the threshold value are determined as one or more selected mean zero-crossing temperatures. If, in step c), more than one selected mean zero-crossing temperature is determined for which the determined aberration is smaller than the predetermined threshold value, then the substrate of the optical component to be manufactured can be selectively adjusted to each of the plurality of determined selected mean zero-crossing temperatures. For example, the substrate can be heat-treated to adjust its mean zero-crossing temperature based on each of the plurality of determined selected mean zero-crossing temperatures.If in step c) no selected mean zero-crossing temperature is determined for which the determined aberration is smaller than the predetermined threshold value, then it can be determined, for example, that the substrate (e.g., the substrate of several representatives for optical components described below) is not suitable for producing an optical component. If the respective determined aberration, for example, has a focus error of the image (i.e., a deviation of an actual focus of the optical system from a target focus), then the threshold value is, for example, 15 nm or less, 10 nm or less, and / or 5 nm or less. If the respective determined aberration, for example, has an overlay error of the image (i.e.,a deviation of an actual position of an object imaged with the aid of the optical system in an image in an image plane of the optical system from a desired position), then the threshold value is, for example, 3 nm or less, 1 nm or less and / or 0.5 nm or less. If the respective determined imaging error has, for example, a spherical wavefront error of the image (i.e. a deviation of an actual wavefront of a beam of rays guided through the optical system from an ideal spherical wave), then the threshold value is, for example, 200 pm or less, 100 pm or less and / or 50 pm or less (RMS deviation). According to one embodiment, in step c) an optimal mean zero-crossing temperature for the substrate of the optical component to be produced is determined as the one of the plurality of mean zero-crossing temperatures for which the determined imaging error is minimal.This allows the average zero-crossing temperature for the substrate of the optical component to be manufactured to be determined even more accurately. For example, several selected average zero-crossing temperatures can first be determined. Then, the one of the several selected average zero-crossing temperatures for which the determined imaging error is minimal can be determined as the optimal average zero-crossing temperature. Carl Zeiss SMT GmbH 9 In this case, in step c), for example, a minimum of the several error values ​​Fi of the imaging of the optical system determined in step b) is determined as the final error FE: F. E = min (F i), for i = 1 to n In the above equation, n denotes the number of possible combinations of the provided normalized distribution function(s) of the zero-crossing temperature and the predetermined mean zero-crossing temperatures. Thus, n is a natural number greater than 1. Furthermore, i denotes an index that runs from 1 to n. In addition, F i a simulation-determined aberration for the i-th of the n possible combinations of the provided distribution function(s) and mean zero-crossing temperatures. FE then gives the minimum of the n simulation-determined aberrations F iThe mean zero-crossing temperature corresponding to this minimum FE is then determined as the optimal mean zero-crossing temperature for the substrate of the optical component to be manufactured. In the above example, in which two different normalized distribution functions and three different values ​​for the mean zero-crossing temperature are provided, thus resulting in six possible combinations, n = 6. Consequently, six different values ​​Fi for the aberration Fi of the optical system are determined based on the six different combinations, and the minimum of these is determined as the final error: F E= min (F1, F2, F3, F4, F5, F6), for n = 6 Carl Zeiss SMT GmbH 10 According to a further embodiment, in step a) a plurality of normalized distribution functions of the zero crossing temperature are provided for a corresponding substrate of a plurality of representatives for optical components. In this way, in a case in which the distribution function of the zero crossing temperature of the substrate of the optical component to be manufactured is unknown, the favorable and / or optimal average zero crossing temperature of the substrate of the optical component to be manufactured can be determined based on a plurality of representative distribution functions of the zero crossing temperature. The plurality of representatives for optical components are, for example, a plurality of physically realized optical components, each with a substrate with the corresponding distribution function of the zero crossing temperature.According to a further embodiment, in step a), a normalized distribution function of the zero-crossing temperature is provided for the substrate of the optical component to be manufactured. By providing the distribution function of the zero-crossing temperature for precisely the substrate of the optical component to be manufactured, the favorable and / or optimal mean zero-crossing temperature for this substrate can be determined even more precisely. If this substrate is then post-processed in a subsequent step so that its mean zero-crossing temperature corresponds to the at least one selected and / or optimal mean zero-crossing temperature determined during the method, imaging errors of the optical system Carl Zeiss SMT GmbH 11 can be further reduced by heat inputs into the optical component to be manufactured.According to a further embodiment, the plurality of representatives are physically realized optical components, and the plurality of zero-crossing temperature distribution functions of the corresponding substrates of the plurality of representatives are measured. As a result, measurement results of a measurement of the zero-crossing temperature distribution functions of the plurality of representatives can be used to replace the unknown zero-crossing temperature distribution function of the component to be manufactured. According to a further embodiment, the substrate of the optical component to be manufactured is physically provided, and the zero-crossing temperature distribution function of the substrate of the optical component to be manufactured is measured. For example, the substrate of the optical component to be manufactured is manufactured before step a).For example, the substrate of the optical component to be manufactured is manufactured with the distribution function of the zero crossing temperature and an initial mean zero crossing temperature. Furthermore, in step c) the at least one selected (i.e. favorable) and / or the optimal mean zero crossing temperature of the substrate is determined. It is also possible, for example, to additionally determine an offset as the difference between the initial mean zero crossing temperature and the at least one selected and / or optimal mean zero crossing temperature. According to a further embodiment, the method comprises: Carl Zeiss SMT GmbH 12 heat treating the substrate of the optical component to be manufactured to set a mean zero crossing temperature of the substrate based on the at least one determined selected mean zero crossing temperature and / or the determined optimal mean zero crossing temperature.This allows the substrate of the optical component to be manufactured to be post-processed so that its mean zero-crossing temperature corresponds to (is equal to) the at least one selected and / or optimal mean zero-crossing temperature determined during the process. In particular, the substrate can be post-processed such that its initial mean zero-crossing temperature, set during substrate manufacture, is corrected by the determined offset. For example, the heat treatment involves a so-called annealing of the substrate.According to a further embodiment, a respective determination of the imaging error of the optical system for each provided distribution function and for the plurality of mutually different predetermined average zero-crossing temperatures comprises: determining a plurality of mutually different individual errors with respect to mutually different error types of the optical system, and determining the imaging error of the optical system based on the plurality of determined individual errors. For example, a plurality of mutually different relative individual errors with respect to the mutually different error types of the optical system are determined. Furthermore, for example, the respective imaging error of the optical system is determined as a maximum, a mean value, a median and / or a quantile of the plurality of determined relative individual errors.Carl Zeiss SMT GmbH 13 For example, the at least one selected average zero-crossing temperature in step c) can also be determined as that of the plurality of average zero-crossing temperatures for which each of the plurality of determined individual errors is smaller than a corresponding predetermined individual threshold value for the corresponding error type. The plurality of mutually different individual errors, in particular, have error values ​​for different types of individual errors. By considering different types of individual errors in the imaging of the optical system, the final error in the imaging of the optical system can be determined even more accurately for each distribution function and each offset.In addition, optionally – for each provided distribution function and each considered mean zero crossing temperature – for example the maximum, the mean, the median and / or the quantile of the several determined individual errors is calculated and then the final error of the imaging of the optical system is taken as this maximum, this mean, this median and / or this quantile. This allows large error contributions to be better taken into account. The maximum of the several determined individual errors is calculated, for example, based on the following equation: Fi = max (fk), for i = 1 to n and k = 1 to m In the above equation, Fi for i = 1 to n denotes the n errors Fi determined in step b) by simulation for the n possible combinations of the provided distribution function(s) and mean zero crossing temperatures.Furthermore, fk for k = 1 to m denotes the m individual errors for a specific distribution function and a specific average zero-crossing temperature. Carl Zeiss SMT GmbH 14 k is an index that runs from 1 to m, where m is a natural number greater than 1 and denotes the number of different individual errors fk. According to a further embodiment, the plurality of determined individual errors are weighted according to predetermined weights. This allows the individual errors to be weighted depending on a planned use of the optical component to be manufactured and the optical system with this component. This allows error contributions from performance parameters that are particularly important for a specific application of the optical component / optical system to be deliberately kept small.The maximum of the multiple weighted individual errors is calculated, for example, based on the following equation: Fi = max (fk / Wk), for i = 1 to n and k = 1 to m In the above equation, W denotes kthe m weights which are used to weight the m individual errors fk. The weights Wk are in particular positive, real numbers greater than 0. According to a further embodiment, the plurality of mutually different individual errors are determined with respect to the mutually different error types and with respect to mutually different setting parameters of an illumination of the optical component of the optical system to be manufactured. Thus, various setting parameters of the planned illumination of the optical component to be manufactured are taken into account in the computer-implemented determination of the individual errors. Consequently, the various Carl Zeiss SMT GmbH 15 types of individual errors can be determined for various simulated illumination scenarios of the optical component to be manufactured.The various setting parameters of the planned illumination of the optical component to be manufactured include, for example, a radiation intensity of a working light (e.g., EUV light) that is irradiated onto the optical component. The various setting parameters of the illumination can, for example, also include a pattern in which the working light is irradiated onto the optical component (e.g., X-dipole, Y-dipole, ring shape, DRAM profile, stripe pattern, etc.). In other words, the illumination setting parameters can include a heat flux distribution with heat flux poles that is caused by working light irradiated onto the optical component to be manufactured in a specific pattern. The various setting parameters of the illumination can, for example, also include a structure of a mask (e.g.,Lithography mask) that is imaged onto a wafer in the image plane of the optical system using the optical component to be manufactured. For example, F. ican then be calculated as follows: Fi = max (fk / Wl), for i = 1 to n, k = 1 to m, and l = 1 to q. In the above equation, Wl denotes the weights used to weight the individual errors fk. The weights Wl are, in particular, positive, real numbers greater than zero. Furthermore, l is an index that runs from 1 to q, where q denotes the number of multiple weights Wl.Carl Zeiss SMT GmbH 16 According to a further embodiment, the plurality of determined individual errors with regard to the mutually different error types include: a deviation of an actual focus of the optical system from a desired focus, a deviation of an actual position of an object imaged with the aid of the optical system in an image plane of the optical system from a desired position of the imaged object, an image shift of an image imaged with the aid of the optical system in an image plane of the optical system, and / or a deviation of an actual wavefront, which images an image in an image plane of the optical system, from a desired wavefront. The individual errors are determined in particular by computer implementation, e.g. based on a simulation of an image with the optical system to be produced. The image shift is, for example, a shift of the image relative to a desired position of the image.An image shift is, for example, a shift of the image in a direction parallel to the image plane of the optical system. The image imaged in an image plane of the optical system is, for example, an image imaged on a wafer of the lithography system. The actual wavefront is, in particular, the wavefront of a beam of rays guided through the optical system. The actual wavefront is, for example, the wavefront of the beam of rays at the location of the image plane. Carl Zeiss SMT GmbH 17 The desired wavefront is, for example, a spherical wave. The deviation of the actual wavefront from the desired wavefront is, for example, a deviation from an ideal spherical wave.According to a further embodiment, the deviation of the actual wavefront from the desired wavefront comprises a wavefront tilt, a wavefront shift, a wavefront astigmatism, a wavefront coma, a wavefront multiple waviness, and / or a wavefront spherical aberration. The wavefront tilt is, for example, a tilt about an axis (e.g., the x- and / or y-axis) arranged parallel to the image plane of the optical system. The wavefront shift is, for example, a shift parallel to the image plane of the optical system (e.g., in the x- and / or y-direction). The multiple waviness is, for example, a wavefront with three wavinesses, four wavinesses, five wavinesses, six wavinesses, etc. According to a further embodiment, the deviation of the actual wavefront from the desired wavefront is quantified in the form of Zernike polynomials.Using Zernike polynomials, a deviation of a real wavefront from an ideal wavefront can be mathematically represented by a sum of polynomials. Zernike polynomials are represented using polar coordinates in a normalized unit circle. Mathematically, the individual Zernike polynomials of a circular area are characterized by polar coordinates with a power series in the radial direction ρ and a Fourier-like series in the direction of the angle Θ. In the general form Z n,±m, n specifies the ordinal number of the polynomial in the radial direction, and m corresponds to the frequency of the angle Θ per revolution of the circle. Polynomials with even n and m=0 are rotationally symmetric, all others are angle-dependent.For example, the Zernike polynomial Z 1,±1 describes a tilt (+1 in the x-direction, -1 in the y-direction), the Zernike polynomial Z 2,0 describes a focus error (spherical error), the Zernike polynomial Z 2,±2 describes an astigmatism, the Zernike polynomial Z 3,±1 describes a coma, the Zernike polynomial Z 3,±3 describes a three-wavelength aberration, the Zernike polynomial Z 4,0 describes a spherical aberration, and the Zernike polynomial Z 4,±2 describes a 4th-order astigmatism. According to a further embodiment, the optical component is a mirror and the substrate is a mirror substrate. In particular, in this case, the optically active surface is a reflective surface. According to a further embodiment, the optical system is a projection system of the lithography system. However, the optical system can also be an illumination system of the lithography system (projection exposure system). The lithography system can be an EUV lithography system.EUV stands for "Extreme Ultraviolet" and refers to a wavelength of the working light between 0.1 nm and 30 nm. The projection exposure system can also be a DUV lithography system. DUV stands for "Deep Ultraviolet" and refers to a wavelength of the working light between 30 nm and 250 nm. Carl Zeiss SMT GmbH 19 According to a further aspect, a computer program product is proposed which comprises instructions which, when the program is executed by at least one computer, cause the computer to carry out the method described above (e.g., one or more embodiments of the method described above). A computer program product, such as a computer program means, can be provided or delivered, for example, as a storage medium, such as a memory card, USB stick, CD-ROM, DVD, or also in the form of a downloadable file from a server in a network.This can be done, for example, in a wireless communications network by transmitting a corresponding file with the computer program product or the computer program means. According to a further aspect, a control device for producing an optical system for a lithography system is proposed. The optical system comprises an optical component with an optically active surface and a substrate.In addition, the control device comprises: a provision device for providing, for a substrate of one or more optical components, a respective normalized distribution function of a zero-crossing temperature of a thermal expansion coefficient of the respective substrate as a function of a location of the substrate, a first determination device for computer-implemented determination, for each provided distribution function and for a plurality of mutually different predetermined average zero-crossing temperatures, of an imaging error of the optical system, and a second determination device for determining a selected average zero-crossing temperature for the substrate of the optical component to be produced as that of the plurality of average Carl Zeiss SMT GmbH 20 zero-crossing temperatures for which the determined imaging error is less than a predetermined threshold value."One" in this case is not necessarily to be understood as being limited to exactly one element. Rather, multiple elements, such as two, three, or more, can also be provided. Any other counting term used here should also not be understood as implying a limitation to the exact number of elements stated. Rather, numerical deviations upwards and downwards are possible unless otherwise stated. The embodiments and features described for the method apply accordingly to the proposed control device, e.g., insofar as they can be implemented by computer, and vice versa. Further possible implementations of the invention also include combinations of features or embodiments not explicitly mentioned above or below with regard to the exemplary embodiments.In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention. Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention is explained in more detail below using preferred embodiments with reference to the attached figures. Fig. 1 shows a schematic meridional section of a projection exposure system for EUV projection lithography according to one embodiment; Carl Zeiss SMT GmbH 21 Fig. 2 shows an optical system of the projection exposure system from Fig. 1 according to one embodiment, wherein the optical system comprises an optical component; Fig. 3 shows a flow diagram of a method for producing an optical system according to one embodiment; Fig. 4 shows a substrate of the optical component from Fig.2 according to one embodiment; Fig. 5 shows a distribution function of a zero-crossing temperature of the substrate from Fig. 4 according to one embodiment; Fig. 6 shows three representatives for optical components according to one embodiment; Fig. 7 shows distribution functions of a zero-crossing temperature of substrates of the optical components from Fig. 6 according to one embodiment; Fig. 8 illustrates a computer-implemented determined individual error of the imaging of the optical system from Fig. 2 according to one embodiment; Fig. 9 illustrates a further computer-implemented determined individual error of the imaging of the optical system from Fig. 2 according to one embodiment; Fig. 10 illustrates an illumination setting of the optical component from Fig. 2 according to one embodiment; Carl Zeiss SMT GmbH 22 Fig. 11 illustrates a weighting in the computer-implemented determination of an imaging error of the optical system from Fig.2 according to an embodiment; Fig. 11A illustrates an aberration of the optical system from Fig. 2 in comparison with a threshold value; and Fig. 12 shows a control device for carrying out the method from Fig. 3 according to an embodiment. In the figures, identical or functionally equivalent elements have been provided with the same reference numerals, unless otherwise stated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale. Fig. 1 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, illumination optics 4 for illuminating an object field 5 in an object plane 6.In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system 2. In this case, the illumination system 2 does not include the light source 3. A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced via a reticle displacement drive 9, in particular in a scanning direction. For the purpose of explanation, Fig. 1 shows a Cartesian coordinate system with an x-direction x, a y-direction y and a z-direction z. The x-direction x runs perpendicular into the drawing plane. The y-direction y runs horizontally and the z-direction z runs vertically. The scanning direction in Fig. 1 runs along the y-direction y. The z-direction z runs perpendicular to the object plane 6. The projection exposure system 1 comprises a projection optics 10.The projection optics 10 is used to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible. A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced via a wafer displacement drive 15, in particular along the y-direction y. The displacement of the reticle 7 on the one hand via the reticle displacement drive 9 and the wafer 13 on the other hand via the wafer displacement drive 15 can be synchronized with one another. Light source 3 is an EUV radiation source.The light source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation 16 has, in particular, a wavelength in the range between 5 nm and 30 nm. The light source 3 can be a plasma source, for example an LPP source (Laser Produced Plasma) or a DPP source (Gas Discharged Produced Plasma). It can also be a synchrotron-based radiation source. The light source 3 can be a free-electron laser (FEL). Carl Zeiss SMT GmbH 24 The illumination radiation 16 emanating from the light source 3 is bundled by a collector 17. The collector 17 may be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces.The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (GI), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light. After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optics 4. The illumination optics 4 comprise a deflection mirror 19 and, downstream of this in the beam path, a first facet mirror 20.The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflecting effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugated to the object plane 6 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. Only a few of these first facets 21 are shown in Fig. 1 as examples.Carl Zeiss SMT GmbH 25 The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or alternatively as convexly or concavely curved facets. As is known, for example, from DE 102008009600 A1, the first facets 21 themselves can also be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can, in particular, be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 102008009600 A1. Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e., along the y-direction y. In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20.If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1614 008 B1, and US Pat. No. 6,573,978. The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets. Carl Zeiss SMT GmbH 26 The second facets 23 can also be macroscopic facets, which can, for example, be round, rectangular or hexagonal in shape, or alternatively facets composed of micromirrors.In this regard, reference is also made to DE 102008009600 A1. The second facets 23 can have flat or, alternatively, convex or concave curved reflection surfaces. The illumination optics 4 thus forms a double-faceted system. This basic principle is also referred to as a fly's eye integrator. It may be advantageous not to arrange the second facet mirror 22 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the second facet mirror 22 can be tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 102017220586 A1. With the aid of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5.The second facet mirror 22 is the last bundle-forming or actually the last mirror for the illumination radiation 16 in the beam path in front of the object field 5. In a further embodiment of the illumination optics 4 (not shown), a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which transmission optics contributes in particular to the imaging of the first facets 21 in the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (GI mirrors, grazing incidence mirrors). The illumination optics 4 has, in the embodiment shown in Fig.1, after the collector 17 there are exactly three mirrors, namely the deflecting mirror 19, the first facet mirror 20 and the second facet mirror 22. In a further embodiment of the illumination optics 4, the deflecting mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22. The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is generally only an approximate imaging. The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1. In the example shown in Fig. 1, the projection optics 10 comprises six mirrors M1 to M6.Alternatives with four, eight, ten, twelve or a different number of mirrors Mi are also possible. The projection optics 10 are doubly obscured optics. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6 and can be, for example, 0.7 or 0.75. Carl Zeiss SMT GmbH 28 The reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, just like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16.These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon. The projection optics 10 have a large object-image offset in the y-direction y between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction y can be approximately as large as a z-distance between the object plane 6 and the image plane 12. The projection optics 10 can, in particular, be anamorphic. In particular, it has different image scales βx, βy in the x- and y-directions x, y. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, + / - 0.125). A positive magnification β means an image without image inversion. A negative sign for the magnification β means an image with image inversion.The projection optics 10 thus results in a reduction in the ratio 4:1 in the x-direction x, i.e., in the direction perpendicular to the scanning direction. The projection optics 10 results in a reduction of 8:1 in the y-direction y, i.e., in the scanning direction. Carl Zeiss SMT GmbH 29 Other image scales are also possible. Image scales with the same sign and absolutely identical in the x- and y-directions x, y, for example, with absolute values ​​of 0.125 or 0.25, are also possible. The number of intermediate image planes in the x- and y-directions x, y in the beam path between the object field 5 and the image field 11 can be the same or, depending on the design of the projection optics 10, can be different. Examples of projection optics with different numbers of such intermediate images in the x and y directions x, y are known from US 2018 / 0074303 A1.Each of the second facets 23 is assigned to exactly one of the first facets 21 to form a respective illumination channel for illuminating the object field 5. This can result in particular in illumination according to the Köhler principle. The far field is broken down into a plurality of object fields 5 with the aid of the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to them. The first facets 21 are each imaged onto the reticle 7 by an assigned second facet 23, superimposed on one another, to illuminate the object field 5. The illumination of the object field 5 is in particular as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.By arranging the second facets 23, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the second facets 23 that guide light, the intensity distribution in the entrance pupil of the Carl Zeiss SMT GmbH 30 projection optics 10 can be adjusted. This intensity distribution is also referred to as illumination setting or illumination pupil filling. A likewise preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels. Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below. The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible.It may also be inaccessible. The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the second facet mirror 22. When the projection optics 10 telecentrically images the center of the second facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined distance of the aperture rays is minimal. This surface represents the entrance pupil or a surface conjugated to it in spatial space. In particular, this surface exhibits a finite curvature. The projection optics 10 may have different positions of the entrance pupil for the tangential and for the sagittal beam path. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7.With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account. Carl Zeiss SMT GmbH 31 In the arrangement of the components of the illumination optics 4 shown in Fig. 1, the second facet mirror 22 is arranged in a surface conjugated to the entrance pupil of the projection optics 10. The first facet mirror 20 is arranged tilted to the object plane 6. The first facet mirror 20 is arranged tilted to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged tilted to an arrangement plane defined by the second facet mirror 22. Fig. 2 shows an optical system 100 (e.g., a part of an optical system 100) with an optical component 102 according to one embodiment. The optical component 102 has a substrate 104 and an optically active surface 106.The optical component 102 is, for example, a mirror with a mirror substrate 104 and a reflective surface 106. The optical system 100 is, for example, a projection optics unit 10 of the EUV lithography system 1 (Fig. 1). However, the optical system 100 can also be, for example, an illumination optics unit 4 of the lithography system 1. The optical component 102 is, for example, one of the mirrors M1 to M6 of the projection optics unit 10 (Fig. 1). The optical component 102 can also be, for example, one of the mirrors 19, 20, 22 of the illumination optics unit 4 (Fig. 1). Although not shown in the figures, the optical component 102 can also be a mirror or a lens of a DUV lithography system. The optical component 102 can heat up due to irradiation with working light 16 (e.g., EUV light 16 of the lithography system 1, Fig. 1) and absorption of the working light 16. As a result, the optical component 102 can be thermally deformed.This thermal deformation can cause aberrations in the optical component 102 or in the optical system 100 comprising the optical component 102. To reduce thermal deformation and associated aberrations, high-quality substrate material 108 is used for the substrate 104. In particular, the material 108 of the substrate 104 has a very small coefficient of thermal expansion ρ. In particular, the material 108 has a zero-crossing temperature ZCT of the coefficient of thermal expansion ρ, at which thermal deformation of the mirror material as a function of a temperature increase is minimal and / or zero. Due to inhomogeneities of the material 108 of the substrate 104, the zero crossing temperature ZCT of the substrate 104 is not homogeneously distributed over a substrate body 110 of the substrate 104, but rather exhibits fluctuations ΔZCT as a function of the location r of the substrate body 110.The location r of the substrate body 110 is, for example, a location in the three-dimensional space spanned by the directions x', y', and z'. A value of the average zero-crossing temperature M of the mirror material 108 as well as the variations ΔZCT of the zero-crossing temperature ZCT as a function of the location r have a direct influence on aberrations of the optical component 102. It is noted that the x', y', and z' directions or the x', y', and z' coordinate system in Figs. 2, 4, and 6 may correspond to or deviate from the x', y', and z' directions or the x', y', and z' coordinate system of Figs. 1, 8, and 9, respectively. In particular, the x', y' and z' directions or the x', y' and z' coordinate system in Figs. 2, 4 and 6 only coincide with the x, y and z directions or the x, y and z coordinate system of Figs. 1, 8 and 9 if an optical axis of the optical component 102 is perpendicular to an image plane of the optical system 100 (e.g.to the image plane 12 in Fig.1 or image plane 302 in Fig.8). For example, Carl Zeiss SMT GmbH 33 the x', y' and z' directions or the x', y' and z' coordinate system in Figs.2, 4 and 6 then correspond to the x, y and z directions or the x, y and z coordinate system of Figs.1, 8 and 9 when the optical component 102 is one of the mirrors M3, M5 or M6 in Fig.1. In the following, a method for producing an optical system 100 for a lithography system 1 is described with reference to Figs. 2 to 11. The optical system 100 has the optical component 102 with the optically active surface 106 and the substrate 104 (Fig.2). In a first step S1 of the method, the substrate 104' is manufactured (Fig. 4). The manufactured substrate 104' comprises a material 108' which, due to the manufacturing process, has a distribution function g(r) of the zero-crossing temperature ZCT' as a function of a location r of the substrate body 110'.Furthermore, the distribution function g(r) has an average zero-crossing temperature M'. In the following, the distribution function g(r) is considered to be a normalized distribution function g(r), which has been normalized based on a value (e.g., the average zero-crossing temperature M') of the actual (i.e., non-normalized) distribution function. The production of the substrate 104' in step S1 may be performed before steps S2 to S4. In other examples, however, step S1 may also be performed after one, several, or all of steps S2 to S4. In a second step S2 of the method, a respective normalized distribution function (e.g. g(r) in Fig.4 or h) is determined for a substrate (e.g. 104' in Fig.4 or 204a, 204b, 204c in Fig.6) of one or more optical components (e.g. 102 in Fig.2 or 202a, 202b, 202c in Fig.6). a (r), h b (r), h c(r) in Fig. 7) of a zero-crossing temperature (e.g. ZCT' in Fig. 4 or ZCTa, ZCTb, ZCTc in Carl Zeiss SMT GmbH 34 Fig. 7) of a thermal expansion coefficient of the respective substrate as a function of a location r of the substrate. In a first variant of step S2, in step S21 a normalized distribution function g(r) of the zero-crossing temperature ZCT' is provided for the substrate 104' (Fig. 4) of the optical component 102 (Fig. 2) to be manufactured. Fig. 5 illustrates an exemplary normalized distribution function g(r) of the normalized zero-crossing temperature ΔZCT of the substrate 104' as a function of the z-location of the substrate 104'. For example, step S1 is carried out before step S21. Then, in step S21, the distribution function g(r) of the zero-crossing temperature ZCT' of the fabricated substrate 104' can be measured and normalized, thus providing the distribution function g(r).If the distribution function g(r) of the zero-crossing temperature ZCT' of the substrate 104' (Fig. 4) of the optical component 102 to be manufactured (Fig. 2) is not available and / or cannot be determined, then the second variant S22 of step S2 of the method can be carried out instead of the first variant S21. In a second variant of step S2, in step S22 of the method, several representatives 202a, 202b, 202c for optical components are provided (Fig. 6). The representatives 202a, 202b, 202c for optical components each have a substrate 204a, 204b, 204c and an optically active surface 206a, 206b, 206c. Furthermore, in step S22, a normalized distribution function ha(r), hb(r), hc(r) of the corresponding zero-crossing temperature ZCTa, ZCTb, ZCTc is provided for each substrate 204a, 204b, 204c of the plurality of representatives 202a, 202b, 202c for optical components. Fig.7 shows, by way of example, normalized distribution functions ha(r), hb(r), hc(r) of the normalized zero-crossing temperature ΔZCT of the corresponding substrate 204a, 204b, 204c as a function of the z-location of the corresponding substrate 204a, 204b, 204c. The multiple representatives 202a, 202b, 202c for optical components and their distribution functions ha(r), hb(r), hc(r) of the zero-crossing temperature ZCT. a , ZCT b , ZCT c can, for example, be provided exclusively digitally in step S22. Alternatively, the plurality of representatives 202a, 202b, 202c for optical components can be physically realized optical components (i.e., physically provided). In this case, their distribution functions ha(r), h b (r), h c (r) the zero crossing temperature ZCT a , ZCT b , ZCT cfor the corresponding substrates 204a, 204b, 204c in step S22 and normalized. In a third step S3 of the method, for each provided normalized distribution function g(r) in Fig.5 or h a (r), h b (r), h c (r) in Fig. 7 and for several different predetermined mean zero-crossing temperatures Mj, an error Fi of an image of the optical system 100 is determined in a computer-implemented manner. Here, j is an index running from 1 to p, where p is a number of different mean zero-crossing temperatures M to be tested. jand is a natural number greater than one. In addition, i denotes an index that runs from 1 to n, where n is a natural number greater than 1 and indicates the number of possible combinations of the provided distribution function(s) and mean zero-crossing temperatures. Thus, Fi is a simulation-determined error for the i-th of the n possible combinations of the provided distribution function(s) (e.g., g(r) in Fig. 5 or h a (r), h b (r), hc(r) in Fig.7) and mean zero-crossing temperatures Mj. Carl Zeiss SMT GmbH 36 If the first variant S21 was carried out in step S2, then in step S3 for the one provided normalized distribution function g(r) of the substrate 104' (Fig.5) and for several different mean zero-crossing temperatures M j an error F iof the image of the optical system 100 is determined by computer implementation. For example only, as illustrated in Fig. 5, four different mean zero-crossing temperatures Mj of 25.0°C, 25.5°C, 26.5°C, and 27.5°C are tested. This means that in the example of Fig. 5, the number of different mean zero-crossing temperatures Mj is four. Furthermore, the combination of a single distribution function g(r) and four different mean zero-crossing temperatures M j four possible combinations. Thus, i = 4 and four different aberrations F i However, in other examples, a different number of values ​​and different values ​​for the mean zero crossing temperature M jbe applied. If the second variant S22 was carried out in step S2, then in step S3 for the several provided normalized distribution functions ha(r), hb(r), hc(r) of the substrates 204a, 204b, 204c (Figs. 6, 7) and for several different average zero crossing temperatures M j an error F i the image of the optical system 100 is determined by computer implementation. As an example only, as illustrated in Fig. 7, four different mean zero-crossing temperatures Mj of 25.0°C, 25.5°C, 26.5°C, and 27.5°C are also tested in this variant. This means that in the example of Fig. 7, the number of different mean zero-crossing temperatures Mj is also four. Furthermore, the combination of, for example, three distribution functions h a (r), h b (r), h c(r) and four different mean zero-crossing temperatures Mj, twelve possible combinations. Thus, i = 12 and twelve different aberrations Fi are calculated. Carl Zeiss SMT GmbH 37 Optionally, in a first variant of step S3, each error Fi can be determined based on several different individual errors fk. In particular, for the determination of each error F i multiple individual errors f k which belong to different types of errors in the imaging of the optical system 100. For example, the different individual errors fk are considered as relative error values. In this first variant of step S4, the error F i the image of the optical system 100, for example, as a maximum of the several determined individual errors fk, e.g. based on the following equation: F i = max (f k), for i = 1 to n and k = 1 to m Where f k the (e.g. relative) individual errors for a specific distribution function g(r) or h a (r), h b (r), h c (r) and a certain mean zero-crossing temperature Mj. Here, k is an index running from 1 to m, where m is a natural number greater than 1 and the number of different individual errors f k In other examples, in step S4, the error Fi of the image of the optical system 100 can also be determined as a mean, a median and / or a quantile of the plurality of determined (e.g., relative) individual errors f k The several different individual errors fk can, for example, be a deviation of an actual focus F Istof the optical system 100 can be a target focus Ftarget (focus error, spherical imaging error, Zernike polynomial ZP of Z 2), as illustrated in Fig. 8. Fig. 8 shows radiation 300 (e.g., the work light 16 in Fig. 1) incident on an image plane 302 of the optical system 100 (Fig. 2). The target focus Ftarget lies in particular in the image plane 302. The actual focus FIst Carl Zeiss SMT GmbH 38 deviates from the target focus Ftarget, resulting in blurring of the image. A deviation of the actual focus FIst from the target focus Ftarget represents an example of an individual error fk, e.g., a first (k = 1) individual error f1. In Fig.8, an error range ΔFfocus is also shown as an example of a threshold value SW (Fig.11A) and / or a single threshold value. For example, an actual focus in the range F Soll ± ΔF fokus lies, an aberration F iwhich is smaller than the threshold value SW. However, the actual focus FIst shown in Fig. 8 is no longer within the permissible range FSoll ± ΔFfokus and the corresponding mean zero-crossing temperature M i thus fulfills the condition for a selected mean zero crossing temperature M aw not. Example values ​​for an error range ΔFfocus, which corresponds to a threshold value SW and / or an individual threshold value for the focus, include, for example, 15 nm or less, 10 nm or less and / or 5 nm or less. The plurality of mutually different individual errors fk can, for example, also be a displacement of a wavefront (e.g., 304 in Fig. 8) relative to a desired wavefront 306, so that an actual position P of an object 402 imaged with the aid of the optical system 100 in an image 400 in an image plane 302 (Fig. 8) of the optical system 100 deviates from a desired position P Sollof the imaged object 404, as illustrated in Fig. 9. A deviation of the actual position Pact from the target position PSoll (overlay error) represents another example of an individual error fk, e.g. a second (k=2) individual error f2. The multiple individual errors fk that are different from one another can, in addition to or instead of, be individual errors f kWith regard to the different types of errors, they can also be individual errors fk with regard to different Carl Zeiss SMT GmbH 39 setting parameters of an illumination of the optical component 102 to be manufactured of the optical system 100. The various setting parameters of the planned illumination of the optical component 102 to be manufactured include, for example, a radiation intensity of a working light (e.g., EUV light 16, Fig. 1) that is irradiated onto the optical component 102. The various setting parameters of the illumination can, for example, also include a pattern 500 or a heat flow distribution 500 in which or with which the working light 16 is irradiated onto the optical component 102. In Fig.10, two heat flux poles 502, 504 (dipole pattern) of a heat flux distribution 500 of an optically active surface 506 of an optical component (e.g., the optical component 102 in Fig.2) are illustrated by way of example.Optionally, in a second variant of step S3, the several identified individual errors f. k according to predetermined weights W l weighted. This allows the individual errors to be weighted depending on a planned use of the optical component 102 to be manufactured and the optical system 100 with this component 102. In this second variant of step S3, Fi is defined, for example, as the maximum of the plurality of weighted individual errors f k for example, calculated based on the following equation: F i = max (f k / W l ), for i = 1 to n , k = 1 to m and l = 1 to q Carl Zeiss SMT GmbH 40 In the above equation, Wl denotes the weights used to weight the individual errors fk. The weights Wl are, in particular, positive, real numbers greater than zero. Furthermore, l is an index that runs from 1 to q, where q is the number of multiple weights W lIn other examples, the error Fi of the image of the optical system 100 can also be expressed as a mean, a median and / or a quantile of the plurality of weighted individual errors f k be determined. In Fig. 11, weights Wl are illustrated as examples. As an example, a weight W1 equal to 0.5 is illustrated, which corresponds to a high weighting, since the term W lis in the denominator in the above equation. As a further example, a weight W2 equal to 1.5 is shown, which corresponds to a low weighting. In a case in which a number p of different setting parameters for the illumination of the optical component 102 with work light 16 are taken into account, q is the mathematical product of p and m (i.e., q = p m). In a case in which no multiple different setting parameters for the illumination of the optical component 102 with work light 16 are taken into account (i.e., only a single setting is applied and thus p = 1), q is equal to m. For example, if two different individual errors fk are considered (i.e., m = 2) and only a single setting parameter for the illumination of the optical component 102 with work light 16 (i.e., p = 1 and q = m), the error Fi is calculated as follows: F i = max (f k / W l ), for i = 1 to n ,k = 1 to 2 and l = 1 to 2 Fi = max (f1 / W1, f2 / W2), for i = 1 to n Carl Zeiss SMT GmbH 41 In an embodiment in which, in addition to, for example, two different individual errors fk (ie m = 2), two different setting parameters for the illumination of the optical component 102 with work light 16 are also taken into account (ie p = 2 and q = 2 m), the error F i calculated as follows: F i = max (f kd / W l ), for i = 1 to n , k = 1 to 2, d = 1 to 2 and l = 1 to 4 Fi = max (f11 / W1, f12 / W2, f21 / W3, f22 / W4), for i = to n Here, f denotes kd the kth individual error at the dth illumination setting. That is, f11 denotes the first individual error f1 at the first illumination setting, f 12 denotes the first individual error f1 at the second lighting setting, f 21denotes the second individual error f2 at the first illumination setting, and f22 denotes the second individual error f2 at the second illumination setting. In a fourth step S4 of the method, at least one selected average zero-crossing temperature Maw for the substrate 104 of the optical component 102 to be produced (Fig. 2) is defined as the average zero-crossing temperature M j determined for which the determined error F i is smaller than a predetermined threshold value SW. In Fig.11A, an aberration F is shown as an example. i of the optical system 102 from Fig. 2, which is smaller than the predetermined threshold value SW. In this example, in step S4, the mean zero-crossing temperature M associated with the aberration Fi is jas the at least one selected mean zero-crossing temperature Maw is determined. Carl Zeiss SMT GmbH 42 If no selected mean zero-crossing temperature Maw is determined in step S4 because none of the determined aberrations Fi is smaller than the predetermined threshold value SW, then it can be determined, for example, that the substrate 104 is not suitable for producing an optical component 102. In this case, step S5 is not carried out. Optionally, instead of or in addition to based on the threshold value SW, an optimal mean zero-crossing temperature M opt for the substrate 104 of the optical component 102 to be manufactured based on a minimum aberration Fi. In other words, in step S4, an optimal mean zero-crossing temperature M optfor the substrate 104 of the optical component 102 to be manufactured (Fig.2) as the average zero-crossing temperature Mj for which the determined error F i is minimal. In this case, in step S4, for example, a minimum FE of the several error values ​​Fi of the image of the optical system 102 determined by computer implementation in step S3 is used as the final error F E determined according to the following equation: F E = min (F i ), for i = 1 to n In the above equation, n denotes the number of possible combinations of the provided normalized distribution function(s) of the zero-crossing temperature (e.g. g(r) in Fig.4 or h a (r), h b (r), h c(r) in Fig. 7) and the predetermined mean zero-crossing temperatures tested in step S3. In addition, FE indicates the minimum of the n errors Fi determined by simulation. Subsequently, the mean zero-crossing temperature Mj (e.g., Mj = M2 = 25.5°C) associated with this minimum FE is determined as the optimal mean zero-crossing temperature Mopt for the substrate 104 of the optical component 102 to be manufactured (Fig. 2). In an optional fifth step S5 of the method, the substrate 104' (Fig. 4) of the optical component 102 to be manufactured (Fig. 2) is heat-treated to determine the mean zero-crossing temperature M' of the substrate 104' based on the at least one selected and / or optimal mean zero-crossing temperature M determined in step S4. aw , M optFor example, the substrate 104' is tempered with suitable parameter settings. In particular, the substrate 104' is post-processed in step S5 such that an average zero-crossing temperature M' initially set during the production of the substrate 104' is offset by an offset between the initially set average zero-crossing temperature M' and the at least one selected and / or optimal average zero-crossing temperature M aw , M opt At the end of step S5, the substrate 104 (Fig. 2) produced in step S1 and post-processed in step S5 has the at least one selected and / or the optimal mean zero-crossing temperature M aw , M opton (Fig. 2). Fig. 12 shows a control device 600 for producing an optical system 100 (Fig. 2) for a lithography system 1 (Fig. 1). The optical system 100 comprises an optical component 102 with an optically active surface 106 and a substrate 104 (Fig. 2). In addition, the control device 600 has a provision device 602. The provision device 602 serves to provide, for a substrate 104', 204a, 204b, 204c of one or more optical components 102, 204a, 204b, 204c, a respective normalized distribution function g(r), h a(r), hb(r), hc(r) of a zero-crossing temperature ZCT', ZCTa, ZCTb, ZCTc of a Carl Zeiss SMT GmbH 44 thermal expansion coefficient ρ of the respective substrate 104', 204a, 204b, 204c as a function of a location r of the substrate 104', 204a, 204b, 204c. Furthermore, the control device 600 has a first determination device 604. The first determination device 604 is configured to, for each provided distribution function g(r), ha(r), hb(r), hc(r) and for each of a plurality of mutually different predetermined average zero-crossing temperatures M j , an error F i an image of the optical system 102 in a computer-implemented manner. In addition, a second determination device 606 is provided for determining at least one selected mean zero-crossing temperature M awand / or an optimal mean zero-crossing temperature Mopt for the substrate 104', 204a, 204b, 204c of the optical component 102 to be produced as the mean zero-crossing temperature M j , for which the determined error F i is smaller than a predetermined threshold value SW or minimal. Although the present invention has been described using exemplary embodiments, it is capable of being modified in many ways.

[0002] Carl Zeiss SMT GmbH 45 LIST OF REFERENCE SYMBOLS 1 Projection exposure system 2 Illumination system 3 Light source 4 Illumination optics 5 Object field 6 Object plane 7 Reticle 8 Reticle holder 9 Reticle displacement drive 10 Projection optics 11 Image field 12 Image plane 13 Wafer 14 Wafer holder 15 Wafer displacement drive 16 Illumination radiation 17 Collector 18 Intermediate focal plane 19 Deflecting mirror 20 First facet mirror 21 First facet 22 Second facet mirror 23 Second facet 100 Optical system 102 Optical component 104, 104' Substrate 106 Optically active surface 108, 108' Material Carl Zeiss SMT GmbH 46 110, 110' Body 202a, 202b, 202c Optical component 204a, 204b, 204c substrate 206a, 206b,206c optically active surface 300 radiation 302 image plane 304 actual wavefront 306 desired wavefront 400 image 402 object 404 object 500 heat flux distribution 502 heat flux pole 504 heat flux pole 506 optically active surface 600 control device 602 supply device 604 determination device 606 determination device ΔF, i Error range ΔF Fokus Error range Δx Position deviation ΔZCT Temperature difference f k Error f1, f2 Error F Error F i Error FIst Actual focus FSoll Target focus Carl Zeiss SMT GmbH 47 g Function ha, hb, hc Function M' Temperature M aw Temperature M j Temperature Mopt Temperature M1 - M4 Temperature M1-M6 Mirror PAct Actual position PSoll Target position ρ, ρ' Thermal expansion coefficient S1-S5 Process steps S21, S22 Process steps SW Threshold value W l Weight W1, W2 Weight x, y, z Directions x', y', z' Directions ZCT, ZCT' Temperature ZCTa, ZCTb, ZCTc Temperature ZP Zernike polynomial

Claims

Carl Zeiss SMT GmbH 48 PATENT CLAIMS 1. Method for producing an optical system (100) for a lithography system (1), wherein the optical system (100) comprises an optical component (102) with an optically active surface (106) and a substrate (104), comprising: a) providing (S2), for a substrate (104', 204a, 204b, 204c) of one or more optical components (102, 202a, 202b, 202c), a respective normalized distribution function (g, ha, hb, hc) of a zero-crossing temperature (ZCT', ZCTa, ZCTb, ZCTc) of a thermal expansion coefficient (ρ') of the respective substrate (104', 204a, 204b, 204c) as a function a location (r) of the substrate (104', 204a, 204b, 204c), b) computer-implemented determination (S3), for each provided distribution function (g, h a , h b , h c ) and for several different predetermined mean zero-crossing temperatures (M j ), an imaging error (F i) of the optical system (102), and c) determining (S4) at least one selected mean zero-crossing temperature (M aw ) for the substrate (104) of the optical component (102) to be produced as that of the plurality of average zero-crossing temperatures (Mj) for which the determined imaging error (Fi) is smaller than a predetermined threshold value (SW).

2. The method according to claim 1, wherein in step c) an optimal average zero-crossing temperature (Mopt) for the substrate (104) of the optical component (102) to be produced is determined as that of the plurality of average zero-crossing temperatures (Mj) for which the determined imaging error (Fi) is minimal.

3. The method according to claim 1 or 2, wherein in step a) a plurality of normalized distribution functions (ha, hb, hc) of the zero-crossing temperature (ZCTa, Carl Zeiss SMT GmbH 49 ZCTb, ZCTc) for a corresponding substrate (204a, 204b, 204c) of a plurality of representatives (202a, 202b, 202c) for optical components are provided.

4. The method according to claim 1 or 2, wherein in step a) a normalized distribution function (g) of the zero-crossing temperature (ZCT') is provided for the substrate (104') of the optical component (102) to be produced.

5. The method according to claim 3, wherein the plurality of representatives (202a, 202b, 202c) are physically realized optical components, and the plurality of distribution functions (ha, hb, hc) of the zero-crossing temperature (ZCTa, ZCTb, ZCT c) of the corresponding substrates (204a, 204b, 204c) of the plurality of representatives (202a, 202b, 202c) are measured.

6. The method according to claim 4, wherein the substrate (104') of the optical component (102) to be manufactured is physically provided, and the distribution function (g) of the zero-crossing temperature (ZCT') of the substrate (104') of the optical component (102) to be manufactured is measured.

7. The method according to one of claims 1 to 6, comprising: heat-treating (S5) the substrate (104') of the optical component (102) to be manufactured to set an average zero-crossing temperature (M') of the substrate (104') based on the at least one determined selected average zero-crossing temperature (Maw) and / or the determined optimal average zero-crossing temperature (Mopt).

8. The method according to any one of claims 1 to 7, wherein a respective determination of the imaging error (Fi) of the optical system (100) for each provided distribution function (g, ha , h b , h c ) and for the several different predetermined mean zero crossing temperatures (Mj): Carl Zeiss SMT GmbH 50 Determining a plurality of mutually different individual errors (fk) with respect to mutually different types of errors of the optical system (100), and determining the imaging error (Fi) of the optical system (100) based on the plurality of determined individual errors (f k).

9. The method according to claim 8, wherein the plurality of determined individual errors (fk) are weighted according to predetermined weights (Wl).

10. The method according to claim 8 or 9, wherein the plurality of mutually different individual errors (fk) are determined with respect to the mutually different error types and with respect to mutually different setting parameters (500) of an illumination of the optical component (102) to be produced of the optical system (100).

11. The method according to one of claims 8 to 10, wherein the plurality of determined individual errors (fk) with respect to the mutually different error types comprise: a deviation (f1) of an actual focus (F Ist ) of the optical system (100) from a target focus (FSoll), a deviation of an actual position (PIst) of an object (402) imaged by means of the optical system (100) in an image plane (302) of the optical system (100) from a target position (P Soll) of the imaged object (404), an image shift of an image (400) imaged by means of the optical system (100) in an image plane (302) of the optical system (100), and / or a deviation of an actual wavefront (304) which images an image (400) in an image plane (302) of the optical system (100) from a desired wavefront (306).

12. The method according to claim 11, wherein the deviation of the actual wavefront (304) from the desired wavefront (306) is a tilt of the wavefront (304), a Carl Zeiss SMT GmbH 51 displacement of the wavefront (304), an astigmatism of the wavefront (304), a coma of the wavefront (304), a multiple waviness of the wavefront (304) and / or a spherical aberration of the wavefront (304).

13. The method according to claim 11 or 12, wherein the deviation of the actual wavefront (304) from the desired wavefront (306) is quantified in the form of Zernike polynomials (ZP).

14. The method according to one of claims 1 to 13, wherein the optical component (102) is a mirror and the substrate (104) is a mirror substrate.

15. The method according to one of claims 1 to 14, wherein the optical system (100) is a projection system (10) of the lithography system (1).Control device (600) for producing an optical system (100) for a lithography system (1), wherein the optical system (100) comprises an optical component (102) with an optically active surface (106) and a substrate (104), and the control device (600) has: a provision device (602) for providing, for a substrate (104', 204a, 204b, 204c) of one or more optical components (102, 202a, 202b, 202c), a respective normalized distribution function (g, h. a , h b , h c ) a zero crossing temperature (ZCT', ZCT a , ZCT b , ZCT c) a thermal expansion coefficient (ρ') of the respective substrate (104', 204a, 204b, 204c) as a function of a location (r) of the substrate (104', 204a, 204b, 204c), a first determination device (604) for computer-implemented determination, for each provided distribution function (g, ha, hb, hc) and for several different predetermined mean zero-crossing temperatures (M j ), an imaging error (F i ) of the optical system (102), and a second determining device (606) for determining a selected mean zero-crossing temperature (Maw) for the substrate (104) of the Carl Zeiss SMT GmbH 52 to be manufactured optical component (102) as that of the plurality of average zero-crossing temperatures (Mj) for which the determined imaging error (Fi) is smaller than a predetermined threshold value (SW).

Images