Method of manufacturing optical system for lithographic apparatus, substrate for optical component for lithographic apparatus, and lithographic apparatus

Abstract

A method of manufacturing an optical system (100) for a lithographic apparatus (1), the optical system comprising an optical component (102) having a substrate (104) cut from an original block (200), the method comprises the steps of: a) providing (S2) a distribution function (g) of zero-crossing temperatures (ZCTR) of the coefficient of thermal expansion ([alpha] R) of the original block as a function of the position (p) of the original block, the distribution function corresponding to a pattern (218) of rotational symmetry of the zero-crossing temperatures with respect to the axis of symmetry (A) of the original block, b) determining (S3), in a computer-implemented manner, an aberration (Fi) of the optical system for the provided distribution function and for each of a plurality of positions (Pi) of a cutout region (D) of the original block, which positions differ from one another, the plurality of positions of the cutout region differing from one another with respect to a radial position (ri) and / or a height position (hi) of the original block, and c) determining (S4), from the plurality of positions (Pi), at least one selected position (Pa) of the cutout region (D) as a position at which the determined aberration (Fi) is less than a predetermined threshold value (SW).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an optical system for a photolithography apparatus, a substrate for an optical component of an optical system for a photolithography apparatus, and a photolithography apparatus having such a substrate.

[0002] The contents of priority applications DE 10 2023 209 473.8 and DE 10 2023 212 752.0 are incorporated herein by reference in their entirety. Background Technology

[0003] Microlithography is used to fabricate microstructured components, such as integrated circuits. Microlithography processes are performed using lithography equipment that includes an illumination system and a projection system. The image of a mask (mask master), illuminated by the illumination system, is projected onto a substrate (e.g., a silicon wafer) via the projection system. This substrate is coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system to transfer the mask structure onto the photosensitive coating of the substrate.

[0004] Driven by the demand for increasingly smaller structures in integrated circuit manufacturing, EUV lithography equipment using light with wavelengths ranging from 0.1 nm to 30 nm, particularly 13.5 nm, is currently under development. Since most materials absorb light at this wavelength, reflective optics (i.e., mirrors) must be used in such EUV lithography equipment, instead of refractive optics (i.e., lens elements) as previously used.

[0005] A problem that arises during this process is that the mirror heats up due to absorbing radiation emitted by the EUV light source. This can lead to thermal deformation of the mirror. Furthermore, the mirror's optical coating may deteriorate due to the increased temperature. Both thermal deformation and damage to the optical coating can adversely affect the mirror's imaging characteristics.

[0006] The imaging quality of the projection system in an EUV lithography apparatus largely depends on the quality of the mirror material. Materials with very low coefficients of thermal expansion are used for the mirror substrate to reduce aberrations caused by mirror heating. Specifically, at the so-called zero-crossing temperature of the mirror material's coefficient of thermal expansion, the deformation of the mirror material with increasing temperature is minimal and / or zero. The average zero-crossing temperature of the mirror material and the variation of the zero-crossing temperature within the mirror substrate volume have a direct impact on aberrations caused by mirror heating. Summary of the Invention

[0007] Against this backdrop, the problem addressed by the present invention is to provide an improved method for manufacturing an optical system for a lithography apparatus and an improved substrate for optical components of the optical system for a lithography apparatus.

[0008] According to a first aspect, a method for manufacturing an optical system for a photolithography apparatus is proposed. The optical system includes optical components having a substrate cut from a raw block. Furthermore, the method includes the following steps:

[0009] a) Provides a distribution function of the zero-crossing temperature of the coefficient of thermal expansion of the original block as a function of the original block's position, which is rotationally symmetric about the axis of symmetry of the original block.

[0010] b) Determine the aberrations of the optical system in a computer-implemented manner, for each of a plurality of distinct locations of the cut region of the original block, given the distribution function, wherein the plurality of locations of the cut region are distinct from each other with respect to the radial and / or height positions of the original block, and

[0011] c) Determine at least one selected location in the cut area as the location among multiple locations where the determined aberration is less than a predetermined threshold.

[0012] This method allows for the cutting of a region from a blank corresponding to a defined cut area, thereby manufacturing a substrate for an optical component. Specifically, the method is used to determine the cut area of ​​the original block, which has a favorable distribution of zero-crossing temperatures. As a result, the method allows for the targeted setting of the zero-crossing temperature distribution within the substrate—within the range of the zero-crossing temperature distribution provided by the original block. This can reduce aberrations in the optical system caused by thermal expansion of the substrate.

[0013] The substrate material of optical components is often non-uniform, resulting in a non-uniform distribution of zero-crossing temperatures across the substrate volume. This even applies to high-performance substrate materials. The non-uniform distribution of zero-crossing temperatures affects the imaging characteristics of the optical components, and therefore the optical systems incorporating these components.

[0014] For a given distribution of zero-crossing temperatures across the volume of the original block, the proposed method now allows for the determination of advantageous and / or optimal notch regions on the substrate of the optical components of a lithography apparatus. As a result, thermal deformation caused by thermal input to the optical components (e.g., by irradiation with EUV light) and subsequent degradation of imaging characteristics can be reduced or avoided.

[0015] Photolithography equipment can be EUV lithography equipment. EUV stands for "Extreme Ultraviolet" and indicates the wavelength of operating light between 0.1 nm and 30 nm. Photolithography equipment can also be DUV lithography equipment. DUV stands for "Deep Ultraviolet" and indicates the wavelength of operating light between 30 nm and 250 nm.

[0016] Optical devices can be, for example, the projection system of a lithography apparatus. However, in other examples, the optical system can also be the illumination system of a lithography apparatus (projection exposure apparatus).

[0017] The optical components of an optical system specifically include the optically effective surface and the substrate.

[0018] For example, the optical component is a mirror, and the substrate is a mirror substrate. In this case, the optically effective surface is specifically the reflective surface.

[0019] Specifically, the substrate is cut out from the original block as a single piece (as a whole).

[0020] The coefficient of thermal expansion specifies how a material's geometry and dimensions change under varying temperatures. For example, the coefficient of thermal expansion is a linear coefficient, which specifies the change in the material's length as a function of temperature.

[0021] The material of the original block (and therefore the material of the substrate made from the original block) is a material with a very low coefficient of thermal expansion. For example, at the desired operating temperature, the coefficient of thermal expansion is in the range of + / -20 ppb / K (parts per billion of Kelvin), + / -15 ppb / K, + / -10 ppb / K, and / or + / -5 ppb / K. However, the coefficient of thermal expansion can also be in different ranges. In such a material with very small thermal expansion, changes in geometry and dimensions due to temperature variations occur only to a very small extent.

[0022] Examples of materials for the raw material (and therefore the substrates made from it) include quartz glass, titanium-doped quartz glass, and glass ceramics. For example, the raw material material is a material with ultra-low thermal expansion (e.g., substrate materials sold by Corning Incorporated under the trademark "ULE," which stands for "ultra-low expansion"). For instance, raw material materials include glass materials made of TiO2-SiO2, where the ultra-low coefficient of thermal expansion is achieved by varying the concentration of TiO2. Another example is a Li2O-Al2O3-SiO2 glass ceramic with a crystalline phase (sold by Schott under the trademark "Zerodur"), where the ultra-low coefficient of thermal expansion is achieved through nanocrystals uniformly distributed within the residual glass phase.

[0023] The coefficient of thermal expansion is temperature-dependent, i.e., a temperature-dependent function. The coefficient of thermal expansion can have a so-called zero-crossing temperature (ZCT). At the zero-crossing temperature, the coefficient of thermal expansion of a material has a zero crossover in its temperature dependence; near this zero crossover, the material experiences little or no thermal expansion with temperature changes.

[0024] For example, the primaries are manufactured in a direct deposition process or a soot process. For instance, primaries are manufactured by depositing glass material from one or more burners onto a rotating billet. In this process, the material is constructed layer by layer while the existing primaries rotate rapidly. This eliminates inhomogeneities, resulting in a rotationally symmetric distribution of inhomogeneities.

[0025] For example, the distribution function of the zero-crossing temperature of the original block corresponds to the distribution function of the material composition of the original block (e.g., titanium content or OH content).

[0026] The distribution function of the zero-crossing temperature of the original block specifies the value of the zero-crossing temperature, for example, for each location of the original block, i.e., for each volume element of the original block.

[0027] In particular, the distribution function of the zero-crossing temperature is a three-dimensional distribution function.

[0028] The original block has a rotationally symmetric distribution function with a zero-crossing temperature. Specifically, the original block has an axis of symmetry that is relative to the axis of rotation. In particular, the distribution function of the original block's zero-crossing temperature is mapped onto itself for rotation about the axis of symmetry through any desired angle. Alternatively, it can be said that the distribution function has a rotationally symmetric pattern of the zero-crossing temperature relative to the axis of symmetry of the original block.

[0029] For example, the original block itself is also rotationally symmetric, resulting in the original block being mapped onto itself as a body of revolution to rotate around any desired angle about the axis of symmetry.

[0030] Specifically, the raw material is the blank material used to manufacture the substrate.

[0031] Specifically, the cut region is a three-dimensional cut region of the original block. For example, the cut region is a cuboid. However, the cut region can have any other geometry. In the embodiments, this can also be applied to one or more deviation cut regions mentioned below.

[0032] Different locations of the cut regions are provided for the purpose of determining the aberrations of the optical system. Alternatively, different cut regions are provided, where the different cut regions differ only in their location within the original block. However, the shapes (e.g., geometries) and volumes of the various cut regions are not different.

[0033] The radial position of the original block, especially its radial position within the original block. The height position of the original block, especially its height position within the original block.

[0034] For example, the corresponding location of the cut area includes the center location of the cut area (e.g., the center and / or geometric center). Alternatively or additionally, the corresponding location of the cut area may also include, for example, the location of the outer boundary, outer edge, and / or outer shape of the cut area. In embodiments, this can also be applied to one or more deviation locations and assigned deviation cut areas(s) mentioned below. In this regard, if applicable, the corresponding or corresponding locations and deviation locations of the cut area and the deviation cut area can be defined as families of points or vectors, or may include such families of points or such vectors.

[0035] For example, using computer-aided simulation, the corresponding aberrations (and deviation aberrations, if applicable) of the optical system are determined based on the various locations of the cut-out region (and the deviation locations of the deviation cut-out region, if applicable). Furthermore, the distribution function of the zero-crossing temperature of the original block provided in step a) and each of the multiple provided locations of the cut-out region of the original block (and the deviation locations of the deviation cut-out region, if applicable) differ from each other, forming the input parameters for the simulation calculation. For each combination of the provided distribution function of the zero-crossing temperature and the provided locations of the cut-out region (and the deviation locations of the deviation cut-out region, if applicable), the aberrations are determined. Specifically, the determined aberrations (and deviation aberrations, if applicable) form the output parameters for the simulation calculation.

[0036] For example, steps a) and / or c) are also performed in a computer-implemented manner. For example, steps a), b) and / or c) are performed by a controller, such as the controller of one or more computers.

[0037] In embodiments, particularly in or before step c), a predetermined threshold is provided in the controller's data memory or on a network (e.g., the cloud), to which the controller is connected or may be connected via data communication. Prior to providing the predetermined threshold, it may be determined or calculated based on one or more characteristics of the optical system, lithography equipment, and / or the wafer to be manufactured by the lithography equipment.

[0038] In an embodiment, in step c), multiple selected locations of the cut area (and the deviation cut area, if applicable) are determined, for example, more than 1, 2, 5 or 10 selected locations, wherein the aberration determined for each selected location is less than a predetermined threshold.

[0039] If more than one selection location is determined in step c) for a cut area where the determined aberration is less than a predetermined threshold, the substrate can be cut from the original block according to each of the multiple determined selection locations.

[0040] If, in step c), the selected location of the cut area with the determined aberration less than the predetermined threshold is not determined, then, for example, it can be determined that the original block is not suitable for manufacturing the substrate.

[0041] For example, if the correspondingly determined aberrations (and deviation aberrations, if applicable) include the focal error of the imaging process (i.e., the deviation between the actual focal point of the optical system and the target focal point), then the threshold is, for example, 15 nm or less, 10 nm or less, and / or 5 nm or less.

[0042] For example, if the correspondingly determined aberrations (and deviation aberrations, if applicable) include overlap errors in the imaging process (i.e., the deviation between the actual position of the object in the image and the target position as imaged in the image plane of the optical system by means of the optical system), then the threshold is, for example, 3 nm or less, 1 nm or less and / or 0.5 nm or less.

[0043] For example, if the correspondingly determined aberrations (and deviation aberrations, if applicable) include the spherical wavefront error of the imaging process (i.e., the deviation of the actual wavefront of the beam guided by the optical system from the ideal spherical wave), then the threshold is, for example, 200 μm or less, 100 μm or less, and / or 50 μm or less (RMS deviation).

[0044] In embodiments of the first aspect, even multiple distribution functions of the zero-crossing temperature of the original block can be used as input parameters to determine the corresponding aberrations, wherein the multiple distribution functions of the zero-crossing temperature of the original block differ from each other by an offset of the average zero-crossing temperature of the distribution functions. In other words, the distribution function of the zero-crossing temperature of the original block having a first average zero-crossing temperature can be determined (e.g., measured). Furthermore, one or more further distribution functions of the zero-crossing temperature of the original block can be determined such that they emerge from the first distribution function of the zero-crossing temperature by adding or subtracting an offset from the average zero-crossing temperature.

[0045] According to an embodiment of the first aspect, in step c), the optimal location of the cut area is determined as the location with the smallest aberration among a plurality of locations.

[0046] This allows for a better determination of the location of the incision area.

[0047] For example, multiple selection locations for the incision area can be determined first. Then, the selection location with the smallest aberration can be chosen as the optimal location from among the multiple selection locations.

[0048] According to another embodiment of the first aspect, the cut area has no axis of symmetry.

[0049] In other words, the cut region does not contain the axis of symmetry. Or, the outer edge of the cut region does not intersect the axis of symmetry of the original block. Specifically, the outer edges of the cut region do not intersect the axis of symmetry of the original block.

[0050] Therefore, the cut-out area of ​​the substrate of the optical element can avoid the region of the original block's axis of symmetry, where the non-uniformity (i.e., variation) of the zero-crossing temperature is particularly large.

[0051] It is also possible to achieve a favorable patterned distribution function of the zero-crossing temperature of the thermal expansion coefficient of the substrate cut from the determined cut area as a function of the substrate position. In particular, the pattern of the zero-crossing temperature of the substrate includes only concentric ring segments (each of which is a partial segment of a complete ring) – but no complete rings. Furthermore, viewed from the outer edge of the substrate, the concentric ring segments have only concave curvature or only convex curvature.

[0052] The deviation cut area mentioned below may also lack an axis of symmetry.

[0053] According to another embodiment of the first aspect, the original block has a cylindrical shape having a cylindrical axis and side surfaces corresponding to the axis of symmetry. Furthermore, the radial position of the original block is a position along the radial direction of the original block, extending from a radius equal to zero at the axis of symmetry to an outer radius (greater than zero) at the side surface.

[0054] Specifically, the cylindrical shape has two opposing end faces (bases) that are connected to each other by side surfaces. For example, the two opposing end faces are arranged parallel to each other.

[0055] Specifically, the cylinder is a straight cylindrical shape. In this case, the two opposite end faces are circular surfaces in every situation.

[0056] According to another embodiment of the first aspect, multiple locations in the cut area each have a radius greater than zero.

[0057] This means that the cut area does not contain an axis of symmetry, where the radius of the original block is equal to zero.

[0058] For example, the entire cut area (i.e., including all its outer edges) has a radius greater than zero.

[0059] The deviation positions of the deviation cut regions mentioned below can also each have radii greater than zero.

[0060] According to another embodiment of the first aspect:

[0061] Multiple locations within the cut area cover a radial range of the original block, extending from the inner radius adjacent to the axis of symmetry to the outer radius at the side surface of the original block, and / or

[0062] Multiple locations in the cut area cover the height range of the original block from the first end face to the second end face.

[0063] Therefore, the determination of optical system aberrations takes into account the location of the cut area, which covers the entire radius of the billet (except for the axis of symmetry itself, where the radius is zero) and / or the entire height of the billet.

[0064] According to another embodiment of the first aspect:

[0065] The original block has first, second, and third directions.

[0066] The third direction is arranged along the axis of symmetry of the original block.

[0067] The first and second directions are arranged perpendicular to each other and respectively perpendicular to the axis of symmetry, and

[0068] The multiple locations of the cut area differ from each other in terms of the radial and / or height position of the original block and in terms of rotation about the first, second and / or third directions.

[0069] Therefore, in order to determine the optimal cut area (i.e. the optimal location of the cut area), one or more rotational degrees of freedom relative to the first, second and / or third direction of the original block can also be considered.

[0070] For certain applications, the applicant has determined that using a substrate manufactured in this way can reduce the aberrations of the optical system by up to 30% to 40%.

[0071] In each case, the first and second directions are arranged parallel to the radial direction of the original block, with an azimuth angle of 90 degrees between the first and second directions. In particular, the third direction coincides with the axis of symmetry.

[0072] According to another embodiment of the first aspect:

[0073] In addition to the aberrations at corresponding locations within the incision region, one or more deviation aberrations from one or more deviation locations within the incision region are determined for each of multiple distinct locations within the incision region.

[0074] Choose one or more deviation locations such that the one or more deviation cut areas defined therefrom are located within the tolerance area surrounding the corresponding cut area defined by the corresponding location, and

[0075] At least one selected location in the incision area is determined as a location where the aberrations determined among multiple locations and one or more determined deviation aberrations are all less than a predetermined threshold.

[0076] By determining and taking into account not only a specific location in the cut area but also one or more deviation locations associated with that specific location, inaccuracies during subsequent substrate cutting (e.g., due to tolerances of the cutting tool) can be accounted for based on the determined selected location and / or the determined optimal location.

[0077] For example, the corresponding tolerance area includes the corresponding cut area.

[0078] For example, the corresponding tolerance area may be 0.01% or more, 0.1% or more, 1% or more, and / or 3% or more larger than the corresponding associated cut area. Additionally or alternatively, the corresponding tolerance area may also be 1 mm or more, 5 mm or more, and / or 10 mm or more larger than the corresponding associated cut area (e.g., in each spatial direction).

[0079] For example, the corresponding tolerance region has the same geometry as the corresponding associated cut region, and is only scaled up compared to the corresponding associated cut region. In particular, the corresponding tolerance region and the corresponding associated cut region have the same center location (e.g., the same center and / or the same geometric center).

[0080] According to another embodiment of the first aspect:

[0081] The original block has first, second, and third directions.

[0082] The third direction is arranged along the axis of symmetry of the original block.

[0083] The first and second directions are arranged perpendicular to each other and respectively perpendicular to the axis of symmetry, and

[0084] One or more deviation locations differ from their corresponding locations in the incision area in the following ways:

[0085] Radial position,

[0086] Height position,

[0087] Displacement in the first, second, and / or third directions,

[0088] Rotation around the first, second, and / or third direction,

[0089] The non-parallel edges of the deviation incision area in the first, second, and / or third directions, respectively, and / or

[0090] One or more deviation incision regions are volumetric deviations from corresponding incision regions defined by corresponding locations.

[0091] According to another embodiment of the first aspect, during the determination of the corresponding aberrations of the optical system in a computer implementation, the error range of the determined aberrations is also determined, and at least one selected location of the cut area is determined as a location among a plurality of locations where the determined aberrations (including their error ranges) are less than a predetermined threshold.

[0092] By considering the error range of aberrations, the selection location of the incision area can be better determined. In particular, it can be ensured that even at the limits of its error range, the determined aberration is less than a predetermined threshold.

[0093] According to another embodiment of the first aspect, the corresponding aberrations are determined by means of computer-based simulation, and the error range of the determined aberrations is determined based on one or more error ranges of one or more input parameters of the simulation.

[0094] This allows us to consider the fact that the input parameters of the simulation may be affected by errors.

[0095] According to another embodiment of the first aspect, the error range of the determined aberration is determined based on the error range of the distribution function of the provided zero-crossing temperature.

[0096] For example, the error range of the provided zero-crossing temperature distribution function includes the error magnitude of the zero-crossing temperature at each location of the original block. For example, the error range of the provided zero-crossing temperature distribution function may also include the deviation between the zero-crossing temperature distribution function and the rotationally symmetric distribution function.

[0097] According to another embodiment of the first aspect, the corresponding aberrations are determined by means of computer-based simulation, and the error range of the determined aberrations is determined based on one or more systematic errors taking into account the simulation.

[0098] For example, systematic errors in simulations include errors resulting from interpolation of data processed during simulation calculations. Systematic errors in simulations can also include biases arising from the selection of computational rules used in the simulation.

[0099] According to another embodiment of the first aspect, determining the corresponding aberrations of the optical system includes:

[0100] Identify multiple distinct individual errors associated with different error types of the optical system, and

[0101] The corresponding aberrations of the optical system are determined based on a number of individually identified errors.

[0102] As described herein, the embodiments and features for determining corresponding aberrations based on multiple determined individual errors can also be applied, where applicable, to determining corresponding deviation aberrations.

[0103] For example, multiple distinct relative individual errors are determined for different error types of the optical system. Furthermore, the corresponding aberrations (and deviation aberrations, if applicable) of the optical system are determined, for example, as the maximum, average, median, and / or quantiles of multiple determined relative individual errors.

[0104] For example, in step c), at least one selected location of the cut area can also be determined as one of a plurality of locations, for which each of the plurality of determined individual errors is less than a corresponding predetermined individual threshold of the corresponding error type.

[0105] In particular, multiple individual errors that are different from each other have error values ​​for different types of individual errors.

[0106] By considering the different types of individual errors in the imaging process of the optical system, for each given location of the provided distribution function and the notched region, the final error of the imaging process of the optical system can be determined even better.

[0107] Furthermore, for example, for each considered location of the provided distribution function and notched region, the maximum, average, median, and / or quantile of several determined individual errors are calculated, and the final error of the imaging process of the optical system is then taken as the maximum, average, median, and / or quantile. This allows for better accounting of large error contributions.

[0108] In this embodiment, multiple determined individual errors are weighted according to predetermined weights. As a result, the individual errors can be weighted according to the intended use of the optical component to be manufactured and the optical system having that component. This allows the error contribution to performance parameters that are particularly important for the specific application of the optical component / optical system to be kept small in a targeted manner.

[0109] According to another embodiment of the first aspect, multiple individual errors that are different from each other are determined with regard to different error types and with regard to setting parameters for illuminating the optical components to be manufactured in the optical system with different operating lights.

[0110] Therefore, during the determination of individual errors implemented by the computer, different setting parameters of the planned illumination of the optical component to be manufactured using operating light (e.g., EUV light) are considered. Thus, various types of individual errors can be determined for different simulated illumination scenarios of the optical component to be manufactured.

[0111] For example, the various setting parameters of the planned illumination for the optical component to be manufactured include the radiant intensity of the operating light (e.g., EUV light) radiated onto the optical component.

[0112] For example, various lighting setup parameters may also include patterns of operating light illuminating the optical component (e.g., X-dipole, Y-dipole, ring, circle, DRAM profile, stripe pattern, irregular pattern, etc.). In other words, lighting setup parameters may include heat flux distributions with heat flux poles, caused by operating light radiating onto the optical component to be manufactured in a specific pattern.

[0113] For example, various lighting setup parameters may also include the structure of a mask (e.g., a photolithography mask) that is imaged onto a wafer in the image plane of an optical system by means of the optical component to be manufactured.

[0114] According to another embodiment of the first aspect, several individual errors are determined regarding the setting parameters for heating the optical component to be manufactured by an external heating device, and these setting parameters are different from each other.

[0115] As a result, during the determination of individual errors implemented by the computer, different setting parameters for the planned heating of the optical component to be manufactured via an external heating device are considered. Therefore, individual errors can be determined for different simulated heating scenarios of the optical component to be manufactured.

[0116] For example, various setting parameters for planned heating of an optical component to be manufactured include the predicted heat input to the optical component, the predetermined temperature to which the optical component to be manufactured should be heated, and / or the heating pattern applied during planned heating. For example, a heating pattern is a temperature pattern that should be achieved in the optical component. For example, a heating pattern is a target temperature map related to two-dimensional or three-dimensional space of the optical component.

[0117] For example, planned heating of an optical component to be manufactured is used to correct one or more types of errors in the imaging process. For example, planned heating of an optical component to be manufactured produces localized compression and / or expansion of the material of the optical component, so as to deform the optical component and make it possible to compensate for specific wavefront errors.

[0118] How well aberrations of different error types can be corrected by heating with an external heating source depends on factors such as the zero-crossing temperature distribution of the optical component substrate. For example, if the cut area of ​​the original block of the substrate has a zero-crossing temperature distribution that is symmetrical (to the best possible extent) with respect to the axis of symmetry of the heating pattern applied during the planned heating of the optical component to be manufactured, it is advantageous to correct aberrations by heating. Furthermore, the compression temperature domain (i.e., the temperature range at which the material compresses due to the applied temperature) and expansion temperature domain (i.e., the temperature range at which the material expands due to the applied temperature) of the optical component to be manufactured depend on the zero-crossing temperatures in the regions of the optical component to be compressed and expanded, respectively. In other words, the compression temperature domain and expansion temperature domain of the optical component to be manufactured depend on the spatial distribution of the zero-crossing temperatures of the substrate of the optical component to be manufactured.

[0119] For example, an external heating device is configured to heat the optically effective surface and / or substrate of the optical component to be manufactured.

[0120] For example, an external heating device is configured to heat the optical component to be manufactured (e.g., its substrate and / or its optically effective surface) on a sector-specific basis. That is, the optical component to be manufactured is not heated uniformly to the same temperature, but rather individual regions (i.e., sectors) of the optical component are heated to different temperatures (depending on the heating pattern). For example, one or more regions of the optical component to be manufactured are heated to temperatures that cause localized compression of the material of the optical component (e.g., its substrate). Furthermore, one or more regions of the optical component to be manufactured are, for example, heated to temperatures that cause localized expansion of the material of the optical component (e.g., its substrate). In particular, localized compression and expansion of the substrate material can occur due to the nonlinear behavior of the substrate material caused by heating. Therefore, whether a specific region (sector) is compressed or expanded by external heating can be set by selecting the temperature of that region. In this way, aberrations can be corrected in a targeted manner.

[0121] For example, external heating devices include radiant heaters (e.g., infrared heaters) configured to radiate heating radiation (e.g., infrared radiation) onto the optical component to be manufactured. However, heating devices may also be configured to heat the optical component by heat conduction rather than heating radiation (i.e., thermal radiation).

[0122] According to another embodiment of the first aspect, heating the optical component to be manufactured by an external heating device includes heating according to one or more different heating patterns, which are accordingly adapted to correct one or more of various error types. Furthermore, multiple distinct individual errors are determined for one or more heating patterns that are different from each other.

[0123] Therefore, during the computer-implemented determination of individual errors, the heat input into the optical component to be manufactured according to the planned heating pattern or various heating patterns can be considered. Thus, the computer-implemented determination of individual errors can also consider the extent (e.g., to what extent) that the planned heating can correct the corresponding error type. Therefore, during the computer-implemented calculation of individual errors, the correction of one or more different error types by planned heating and the quality of such correction, which depends on the distribution of the zero-crossing temperature of the substrate of the optical component, can be considered.

[0124] According to another embodiment of the first aspect, the plurality of determined individual errors, which differ from each other in error type, include the following:

[0125] The deviation between the actual focal point of the optical system and the target focal point.

[0126] By utilizing the deviation between the actual position of the object imaged in the image plane of the optical system and the target position of the imaged object,

[0127] Image displacement of the image formed in the image plane of the optical system by means of the optical system, and / or

[0128] The deviation between the actual wavefront and the target wavefront when the image is projected onto the image plane of the optical system.

[0129] In particular, individual errors can be determined in a computer-implemented manner, for example, based on simulations of the imaging process using the optical system to be manufactured.

[0130] For example, image displacement is the displacement of an image relative to a target position in the image. For example, image displacement is the displacement of an image in a direction parallel to the image plane of the optical system.

[0131] An image is formed in the image plane of an optical system, such as an image formed on a wafer in a photolithography device.

[0132] The actual wavefront is specifically the wavefront of a beam of light that is guided through an optical system. For example, the actual wavefront is the wavefront of a beam of light located at the image plane.

[0133] For example, the target wavefront is a spherical wave. The deviation between the actual wavefront and the target wavefront is, for example, the deviation from an ideal spherical wave.

[0134] According to another embodiment of the first aspect:

[0135] The deviation between the actual wavefront and the target wavefront includes wavefront tilt, wavefront displacement, wavefront astigmatism, wavefront coma, higher-order (n) foil aberrations of the wavefront, and / or spherical aberrations of the wavefront, and / or

[0136] The deviation between the actual wavefront and the target wavefront is quantified in the form of Zernike polynomials.

[0137] For example, the tilt of the wavefront is the tilt about an axis (e.g., the x-axis and / or y-axis) that is arranged parallel to the image plane of the optical system.

[0138] For example, the displacement of the wavefront is a displacement parallel to the image plane of the optical system (e.g., in the x and / or y directions).

[0139] Higher-order (n) foil aberrations include wavefront trilobal aberration, tetralobal aberration, pentalobal aberration, hexalobal aberration, etc.

[0140] Using Zernike polynomials, the deviation of the actual wavefront from the ideal wavefront can be mathematically represented by the sum of polynomials. Zernike polynomials are represented in polar coordinates within a normalized unit circle. Mathematically, each Zernike polynomial in the circular region is characterized by polar coordinates, which have a power series in the radial direction ρ and a Fourier-like series in the direction of angle Θ. In the general form Zn,±m, n specifies the order of the polynomial in the radial direction, and m corresponds to the frequency per revolution of angle Θ. Polynomials with even n and m=0 are rotationally symmetric, and all other polynomials are angle-dependent.

[0141] For example, the Zernike polynomial Z1,±1 describes tilt (+1 in the x-direction and -1 in the y-direction), the Zernike polynomial Z2,0 describes defocus (spherical error), the Zernike polynomial Z2,±2 describes astigmatism, the Zernike polynomial Z3,±1 describes coma, the Zernike polynomial Z3,±3 describes tricleaf aberration, the Zernike polynomial Z4,0 describes spherical aberration, and the Zernike polynomial Z4,±2 describes fourth-order astigmatism.

[0142] According to another embodiment of the first aspect, the method includes the following steps:

[0143] Provide the original block, and

[0144] The distribution function of the zero-crossing temperature of the original block is measured.

[0145] The distribution function of the zero-crossing temperature is measured specifically for the entire volume of the original block (i.e., all locations).

[0146] When measuring the distribution function of the zero-crossing temperature of the original block, the error range of the distribution function of the zero-crossing temperature can also be determined.

[0147] According to another embodiment of the first aspect, the method includes the following steps:

[0148] Provide the original block, and

[0149] The substrate is cut from the original block according to at least one determined selection position of the cut area and / or the determined optimal position of the cut area.

[0150] Specifically, the original block is provided physically. Furthermore, the original block is provided specifically before step a).

[0151] Specifically, the substrate is cut out from the original block into a single piece (i.e., the whole).

[0152] According to a second aspect, a substrate for an optical component of an optical system for a photolithography apparatus is proposed. The substrate includes a distribution function of the zero-crossing temperature of the coefficient of thermal expansion as a function of the substrate's position. Furthermore, the distribution function includes a pattern of zero-crossing temperatures comprising a plurality of concentric ring segments, each of which is a partial segment of a complete ring.

[0153] The corresponding complete rings, especially circular rings.

[0154] According to the embodiment of the second aspect:

[0155] The auxiliary lines of the substrate are defined such that they are arranged perpendicular to mutually parallel tangents at the ring segment and extend through the virtual center of the virtual complete ring corresponding to the ring segment.

[0156] The auxiliary lines are arranged parallel to the longitudinal direction of the substrate, or

[0157] The auxiliary lines are arranged at an angle to the longitudinal direction of the substrate.

[0158] According to a third aspect, a photolithography apparatus is proposed. The photolithography apparatus includes a substrate as described above and / or an optical system having optical components having the substrate as described above.

[0159] According to another aspect, a computer program product is proposed, which includes instructions that, when executed by at least one computer, cause the computer to perform the above-described method (e.g., one or more embodiments of the above-described method).

[0160] Computer program products, such as computer program media, can be provided or supplied as storage media, such as memory cards, USB sticks, CD-ROMs, DVDs, or as files downloadable from a server on a network. For example, in a wireless communication network, this can be achieved by using computer program products or computer program devices to transmit appropriate files.

[0161] According to another aspect, a controller for an optical system used in manufacturing photolithography equipment is proposed. The controller includes:

[0162] A providing device for performing step a) of the above method,

[0163] The first determining device for performing step b) of the above method, and

[0164] The second determining device for performing step c) of the above method.

[0165] The corresponding units, such as controllers, providing devices, and first and second determining devices, can be implemented using hardware and / or software technologies. If implemented in hardware, the corresponding unit can be in the form of a device or part of a device, such as a computer or microprocessor, or in the form of a control computer. In a software implementation, the corresponding unit can be implemented as a computer program product, function, routine, part of program code, or executable object.

[0166] According to another aspect, a method for manufacturing an optical system for a photolithography apparatus is proposed. The optical system includes optical components having a substrate cut from a raw block. Furthermore, the method includes the following steps:

[0167] a) Provides a distribution function of the zero-crossing temperature of the coefficient of thermal expansion of the original block as a function of the original block's position, which is rotationally symmetric about the axis of symmetry of the original block.

[0168] b) Using a computer-implemented method, determine measurements of the non-uniformity of the zero-crossing temperature of the cut region for each of several distinct locations of the cut region of the original block, wherein the multiple locations of the cut region differ from each other with respect to the radial and / or height positions of the original block, and

[0169] c) The optimal location of the incision area is determined as the location with the smallest determined non-uniformity measurement among multiple locations.

[0170] Measurements of the non-uniformity of the zero-crossing temperature in the cut region include, for example, parameters of the distribution function of the zero-crossing temperature in the cut region. Specifically, the distribution function of the zero-crossing temperature in the cut region is a function of the location of the cut region. Furthermore, the distribution function of the zero-crossing temperature in the cut region is particularly a subset of the distribution function of the zero-crossing temperature of the original block for the corresponding cut region.

[0171] For example, the parameters for measuring the non-uniformity of the zero-crossing temperature in the cut region include the deviation from a predetermined nominal value, the determined average and / or determined median of the distribution function of the cut region, and / or the deviation from the predetermined nominal distribution function of the zero-crossing temperature.

[0172] For example, the statistical distribution function of the zero-crossing temperature of the cut-off region can be determined based on the distribution function of the zero-crossing temperature of the cut-off region, which is a function of the location of the cut-off region. For example, the mean, median, and / or (statistical) standard deviation of the zero-crossing temperature can be determined based on the statistical distribution function of the zero-crossing temperature of the cut-off region. In this case, the parameters used to measure the non-uniformity of the zero-crossing temperature of the cut-off region will deviate from the determined mean, median, and / or standard deviation.

[0173] In the present context, “one (n)” should not necessarily be understood as limited to exactly one element. Instead, multiple elements, such as two, three, or more, can be expected. Any other numbers used herein should also not be construed as limiting the exact number of elements stated herein. Rather, upward and downward numerical deviations are possible unless otherwise stated.

[0174] The embodiments and features described according to the method of the first aspect are accordingly applicable to the further proposed aspects, and vice versa.

[0175] Other possible embodiments of the invention include combinations of features or embodiments not explicitly mentioned in the preceding or following descriptions of exemplary embodiments. In such cases, those skilled in the art will also add various aspects as improvements or supplements to the corresponding basic form of the invention. Attached Figure Description

[0176] Other advantageous constructions and aspects of the invention are the subject of the dependent claims and the exemplary embodiments described below. The invention is explained in detail below with reference to the accompanying drawings based on preferred embodiments.

[0177] Figure 1 A schematic meridional section of a projection exposure apparatus for EUV projection lithography according to one embodiment is shown;

[0178] Figure 2 An example is shown. Figure 1 The optical system of the projection exposure device, the optical system comprising optical components;

[0179] Figure 3 A method for manufacturing according to one embodiment is shown. Figure 1 A flowchart of a method for using the optical system of a projection exposure device;

[0180] Figure 4 A method for manufacturing according to one embodiment is shown. Figure 2 A perspective view of the original block of the substrate for the optical components;

[0181] Figure 5 An embodiment is shown. Figure 4 A plan view of the original block;

[0182] Figure 6 An embodiment is shown. Figure 4 Another planar view of the original block;

[0183] Figure 7 An embodiment is shown. Figure 4 Another planar view of the original block;

[0184] Figure 7A It shows Figure 7 Details;

[0185] Figure 8 An example of a [example] is shown. Figure 4 A cross-sectional view of the original block;

[0186] Figure 8A It shows Figure 8 Details;

[0187] Figures 8B to 8E They are shown respectively Figure 8A The incision area and tolerance area, and one or more deviation incision areas corresponding to the incision area;

[0188] Figure 9 An embodiment is shown. Figure 4 Another cross-sectional view of the original block;

[0189] Figure 9A It shows the comparison with the threshold. Figure 2 Aberrations of the optical system;

[0190] Figure 10 The method of determining from a computer implementation according to one embodiment is illustrated. Figure 2 Individual errors in the imaging process of an optical system;

[0191] Figure 11 The method of determining from a computer implementation according to one embodiment is illustrated. Figure 2 Another separate error in the imaging process of an optical system;

[0192] Figure 12 An embodiment is shown. Figure 2 The optical components are equipped with an illumination setting for operating light;

[0193] Figure 12A An embodiment is shown. Figure 2 Heating of optical components;

[0194] Figure 12B The following is an explanation of one embodiment of the method. Figure 12A The heating pattern applied during the heating process;

[0195] Figure 13 The use according to one embodiment is shown. Figure 3 Substrates manufactured by the method; and

[0196] Figure 14 The use according to another embodiment is shown. Figure 3 Another substrate manufactured using the same method.

[0197] Unless otherwise specified, identical or functionally equivalent elements have the same reference numerals in the accompanying drawings. Furthermore, it should be noted that the illustrations in the drawings are not necessarily drawn to scale. Detailed Implementation

[0198] Figure 1 This illustrates an embodiment of a projection exposure apparatus 1 (lithography apparatus), particularly an EUV lithography apparatus. One embodiment of the illumination system 2 of the projection exposure apparatus 1, in addition to a light source or radiation source 3, also includes an illumination optical unit 4 for illuminating the object field 5 in the object plane 6. In an alternative embodiment, the light source 3 may also be provided as a module separate from the rest of the illumination system 2. In this case, the illumination system 2 does not include the light source 3.

[0199] The mask master 7, arranged in the object field 5, is exposed. The mask master 7 is held by the mask master holder 8. The mask master holder 8 can be displaced by the mask master displacement driver 9, especially in the scanning direction.

[0200] For the purpose of explanation, Figure 1 A Cartesian coordinate system with x-direction x, y-direction y, and z-direction z is shown. The x-direction x extends vertically into the plane shown in the figure. The y-direction y extends horizontally, and the z-direction z extends vertically. Figure 1 The scanning direction extends in the y-direction (y). The z-direction (z) extends perpendicular to the object plane (6).

[0201] The projection exposure apparatus 1 includes a projection optics unit 10. The projection optics unit 10 is used to image the object field 5 onto an image field 11 in an image plane 12. The image plane 12 extends 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.

[0202] The structure on the mask master 7 is imaged onto the photosensitive layer of the wafer 13 in the region of the image field 11 arranged in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be moved by a wafer displacement driver 15, particularly in the y-direction. The displacement of the mask master 7 can be achieved first by the mask master displacement driver 9, and then by the wafer displacement driver 15, so as to synchronize them.

[0203] Light source 3 is an EUV radiation source. Light source 3 specifically emits EUV radiation 16, which is also referred to below as working radiation, illumination radiation, or illuminating light. In particular, the working radiation 16 has a wavelength in the range of 5 nm to 30 nm. Light source 3 can be a plasma source, such as an LPP (laser-generated plasma) source or a GDPP (gas discharge-generated plasma) source. It can also be a synchrotron-based radiation source. Light source 3 can be a free-electron laser (FEL).

[0204] Illumination radiation 16 emitted from light source 3 is focused by light collector 17. Light collector 17 may be a light collector having one or more elliptical and / or hyperboloidal reflective surfaces. Illumination radiation 16 may be incident on at least one reflective surface of light collector 17 at either grazing incidence (GI) (i.e., at an angle of incidence greater than 45°) or normal incidence (NI) (i.e., at an angle of incidence less than 45°). Light collector 17 may be structured and / or coated, firstly to optimize its reflectivity to the radiation used, and secondly to suppress intrusive light.

[0205] Downstream of the light collector 17, the illumination radiation 16 propagates through the intermediate focal point in the intermediate focal plane 18. The intermediate focal plane 18 can represent the separation between the radiation source module, which includes the light source 3 and the light collector 17, and the illumination optical unit 4.

[0206] The illumination optics unit 4 includes a deflecting mirror 19 and a first faceted mirror 20 disposed downstream of it in the beam path. The deflecting mirror 19 may be a planar deflecting mirror, or alternatively, a mirror with beam-affecting effects beyond pure deflection. Alternatively or additionally, the deflecting mirror 19 may be designed as a spectral filter that separates the wavelength of the illumination radiation 16 used light from external light of different wavelengths. If the first faceted mirror 20 is disposed in a plane of the illumination optics unit 4 that is optically conjugate to the object plane 6 as a field plane, it is also called a field faceted mirror. The first faceted mirror 20 includes a plurality of individual first facets 21, which may also be called field facets. Figure 1 Only some of these first facets 21 are shown as examples.

[0207] The first facet 21 can be implemented as a macroscopic facet, particularly as a rectangular facet or as a facet with an arcuate or partially circular edge profile. The first facet 21 can be in the form of a planar facet or alternatively in the form of a convex or concave curved facet.

[0208] As is known, for example, from DE 10 2008 009 600 A1, the first facet 21 itself can also be composed of multiple individual mirrors, particularly multiple micromirrors. In particular, the first facet mirror 20 can be in the form of a microelectromechanical system (MEMS system). For details, refer to DE 10 2008 009 600 A1.

[0209] The illumination radiation 16 propagates horizontally (i.e. in the y-direction) between the light collector 17 and the deflector 19.

[0210] In the beam path of the illumination optical unit 4, the second faceted mirror 22 is positioned downstream of the first faceted mirror 20. If the second faceted mirror 22 is arranged in the pupil plane of the illumination optical unit 4, it is also called a pupil faceted mirror. The second faceted mirror 22 can also be arranged at a certain distance from the pupil plane of the illumination optical unit 4. In this case, the combination of the first faceted mirror 20 and the second faceted mirror 22 is also called a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US 6,573,978.

[0211] The second faceted reflector 22 includes multiple second facets 23. In the case of a pupil faceted reflector, the second facet 23 is also called the pupil facet.

[0212] The second facet 23 can also be a macroscopic facet, which may, for example, have circular, rectangular, or hexagonal boundaries, or alternatively, a facet composed of micromirrors. In this regard, see again DE 10 2008 009 600 A1.

[0213] The second facet 23 may have a planar reflective surface, or alternatively, a convex or concave curved reflective surface.

[0214] The illumination optics unit 4 thus forms a biplane system. This basic principle is also known as a fly-eye integrator.

[0215] It may be advantageous to arrange the second faceted mirror 22 imprecisely in a plane that is optically conjugate to the pupil plane of the projection optics unit 10. In particular, the second faceted mirror 22 may be arranged tilted relative to the pupil plane of the projection optics unit 10, as described in DE 10 2017 220 586 A1.

[0216] With the aid of the second faceted mirror 22, the first facet 21 is imaged into the object field 5. The second faceted mirror 22 is the final beam-shaping mirror, or in fact the final mirror of the illumination radiation 16 in the beam path upstream of the object field 5.

[0217] In another embodiment (not shown) of the illumination optics unit 4, a transmission optics unit may be arranged in the beam path between the second facet mirror 22 and the object field 5. This transmission optics unit is particularly helpful in imaging the first facet 21 into the object field 5. The transmission optics unit may have exactly one mirror, or alternatively two or more mirrors, arranged sequentially in the beam path of the illumination optics unit 4. The transmission optics unit may specifically include one or two normal incident mirrors (NI mirrors) and / or one or two grazing incident mirrors (GI mirrors).

[0218] exist Figure 1In the embodiment shown, the illumination optical unit 4 has three mirrors downstream of the light collector 17, specifically a deflecting mirror 19, a first faceted mirror 20, and a second faceted mirror 22.

[0219] In another embodiment of the illumination optical unit 4, the deflecting mirror 19 may be omitted. Therefore, the illumination optical unit 4 may have two mirrors downstream of the light collector 17, specifically a first faceted mirror 20 and a second faceted mirror 22.

[0220] Imaging the first plane 21 onto the object plane 6 via the second plane 23 or using the second plane 23 and the transmission optical unit is usually only an approximate imaging.

[0221] The projection optical unit 10 includes a plurality of mirrors Mi, which are numbered sequentially according to their arrangement in the beam path of the projection exposure device 1.

[0222] exist Figure 1 In the example shown, the projection optics unit 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The projection optics unit 10 is a double-shielded optics unit. The penultimate mirror M5 and the last mirror M6 each have a channel opening for illumination radiation 16. The projection optics unit 10 has an image-side numerical aperture greater than 0.5, and may also be greater than 0.6, and may be, for example, 0.7 or 0.75.

[0223] The reflective surface of mirror Mi can be a free-form surface without a rotational axis of symmetry. Alternatively, the reflective surface of mirror Mi can be designed as an aspherical surface with exactly one rotational axis of symmetry in its shape. Like the mirror of illumination optics unit 4, mirror Mi can have a highly reflective coating for illumination radiation 16. These coatings can be designed as multilayer coatings, particularly with alternating layers of molybdenum and silicon.

[0224] The projection optical unit 10 has a large object-image offset in the y-direction y between the y-coordinate of the center of the object field 5 and the y-coordinate of the center of the image field 11. This object-image offset in the y-direction y can have a magnitude approximately the same as the z-distance between the object plane 6 and the image plane 12.

[0225] In particular, the projection optical unit 10 can have a deformable design. It has different imaging ratios βx and βy, especially in the x and y directions. The two imaging ratios βx and βy of the projection optical unit 10 are preferably (βx, βy) = (+ / -0.25, + / -0.125). A positive imaging ratio β refers to imaging without image inversion. A negative sign for the imaging ratio β indicates imaging with image inversion.

[0226] The projection optical unit 10 thus results in a 4:1 size reduction in the x-direction (i.e., in the direction perpendicular to the scanning direction).

[0227] The projection optical unit 10 results in an 8:1 size reduction in the y-direction (i.e., in the scanning direction).

[0228] Other imaging scales are also possible. Imaging scales with the same sign and the same absolute value in the x-direction (x) and y-direction (y) are also possible, for example, with absolute values ​​of 0.125 or 0.25.

[0229] The number of intermediate image planes in the beam path between object field 5 and image field 11 in the x-direction and y-direction may be the same or different, depending on the embodiment of projection optics unit 10. Examples of projection optics units with different numbers of such intermediate images in the x-direction and y-direction are known from US 2018 / 0074303 A1.

[0230] In each case, one of the second facets 23 is assigned to one of the first facets 21 to form an illumination channel for illuminating the object field 5. This can in particular result in illumination according to Köhler's principle. The far field is decomposed into multiple object fields 5 by means of the first facets 21. The first facets 21 produce multiple images with intermediate focal points on the second facets 23 respectively assigned to them.

[0231] The first surface 21, through the assigned second surface 23, is imaged onto the master mask 7 in an overlapping manner to illuminate the object field 5. The illumination of the object field 5 is particularly designed to be as uniform as possible, preferably with a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0232] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by the arrangement of the second facet 23. The intensity distribution in the entrance pupil of the projection optical unit 10 can be set by selecting the illumination channel of the guiding light (specifically the subgroup of the second facet 23). This intensity distribution is also referred to as the illumination setting or illumination pupil filling.

[0233] By redistributing the illumination channels, the uniformity of the illumination pupils of the illumination optical unit 4 can be achieved in a defined manner within a portion of the illumination area.

[0234] Other aspects and details of the illumination of the object field 5 and, in particular, the entrance pupil of the projection optical unit 10 will be described below.

[0235] The projection optical unit 10 may specifically have a concentric entrance pupil. The latter may be accessible or inaccessible.

[0236] The entrance pupil of the projection optics unit 10 is typically not precisely illuminated by the second faceted mirror 22. During the imaging process of the projection optics unit 10 (which images the center of the second faceted mirror 22 onto the wafer 13 at a telecentric angle), the aperture rays typically do not intersect at a single point. However, it is possible to find a region where the spacing between pairs of defined aperture rays becomes minimal. This region represents the entrance pupil or a region in real space conjugate with it. In particular, this region exhibits a finite curvature.

[0237] It is possible that the projection optics unit 10 has different entrance pupil positions for the tangential beam path and for the sagittal beam path. In this case, an imaging element, particularly the optical component portion of the transmission optics unit, should be provided between the second faceted mirror 22 and the mask mother 7. This optical element allows for the consideration of different entrance pupil positions for the tangential and sagittal beam paths.

[0238] exist Figure 1 In the arrangement of the components of the illumination optical unit 4 shown, the second faceted mirror 22 is arranged in the region conjugate with the entrance pupil of the projection optical unit 10. The first faceted mirror 20 is arranged tilted relative to the object plane 6. The first faceted mirror 20 is arranged tilted relative to the arrangement plane defined by the deflecting mirror 19. The first faceted mirror 20 is arranged tilted relative to the arrangement plane defined by the second faceted mirror 22.

[0239] Figure 2 An optical system 100 (e.g., a portion of an optical system 100) with an optical component 102 is shown according to one embodiment. The optical component 102 includes a substrate 104 and an optically effective surface 106. For example, the optical component 102 is a mirror having a mirror substrate 104 and a reflective surface 106.

[0240] For example, optical system 100 is the projection optical unit 10 of EUV lithography equipment 1 ( Figure 1 However, the optical system 100 can also be, for example, the illumination optical unit 4 of the lithography apparatus 1.

[0241] For example, optical component 102 is projection optical unit 10 ( Figure 1 The optical component 102 may also be one of the reflectors M1 to M6 of the illumination optical unit 4. For example, the optical component 102 may also be one of the reflectors 19, 20, and 22 of the illumination optical unit 4. Figure 1 ).

[0242] Although not shown in the figure, the optical component 102 may also be a mirror or lens element of a DUV lithography device.

[0243] Optical component 102 can be powered by operating light 16 (e.g., EUV light 16 from lithography equipment 1). Figure 1The optical component 102 heats up due to radiation and absorption of the operating light 16. This can cause thermal deformation of the optical component 102. Aberrations F in the optical component 102 or the optical system 100 including the optical component 102 may occur due to this thermal deformation.

[0244] High-quality substrate material 108 is used for substrate 104 to reduce associated thermal deformation and aberration F. In particular, the material 108 of substrate 104 has a very small coefficient of thermal expansion α. ​​Specifically, the material 108 has a zero-crossing temperature ZCT of the coefficient of thermal expansion α, at which the thermal deformation of the mirror material 108 due to temperature rise is minimal and / or zero.

[0245] Due to the non-uniformity of the material 108 of the substrate 104, the zero-crossing temperature ZCT of the substrate 104 is unevenly distributed on the substrate body 110 of the substrate 104; instead, it has a fluctuation ΔZCT as a function of the position of the substrate body 110. The value of the average zero-crossing temperature M of the substrate material 108 and the fluctuation ΔZCT of the zero-crossing temperature ZCT with position have a direct impact on the aberration F of the optical component 102, and therefore have a direct impact on the optical system 100 having the optical component 102.

[0246] The following is for reference. Figures 3 to 12 A method for manufacturing an optical system 100 for a photolithography apparatus 1 is described. The optical system 100 includes an optical component 102 having an optically effective surface 106 and a substrate 104. Figure 2 ).

[0247] In the first optional step S1 of the method, the original block 200 is provided. Figure 4 In this process, substrate 104 can be cut from the original block 200. Figure 2 ).

[0248] Original block 200 is made of materials with a very small coefficient of thermal expansion α. R It is made of material 202. In particular, material 202 has a coefficient of thermal expansion α. R zero crossing temperature ZCT R At the zero-crossing temperature ZCT R At that point, the thermal deformation of material 202 due to temperature rise is minimal and / or zero.

[0249] Due to the inhomogeneity of material 202 in the original block 200, the zero-crossing temperature ZCT of the original block 200 is... R It is not uniformly distributed on the body 204 of the original block 200; instead, it has a mean zero-crossing temperature M as a function of the position p of the original block body 204. R fluctuation ΔZCT R .

[0250] For example, the original block 200 is manufactured in a direct deposition process or in a soot process.

[0251] In the second step S2 of this method, the zero-crossing temperature ZCT of the original block 200 is provided. R The distribution function g(p).

[0252] For example, in step S2, the zero-crossing temperature ZCT of the original block 200 is measured. R The distribution function g(p). However, the zero-crossing temperature ZCT of the original block 200. R The distribution function g(p) can also be determined, for example, using computer-aided methods based on the parameters of the original block 200.

[0253] The provided zero-crossing temperature ZCT of the original block 200 R The distribution function g(p) is, for example, specified for each position p of the original block 200. j zero crossing temperature ZCT R The value of ZCT j As an example, Figure 4 The image shows magnified details of the original block 200, which clarifies the multiple volume elements V of the original block 200. j As an example, a magnified detail of the original block 200 shows 27 (3 × 3 × 3) volume elements V. j Three of the volume elements are labeled with reference numerals. Furthermore, for each volume element V... j , Figure 4 The corresponding volume element V is marked. j In the Cartesian coordinate system shown, the coordinates x', y', z' are... j y j , z j Position p in j For example, with each position p assigned to the original block 200 j In step S2, the location p is provided and / or measured. j zero crossing temperature ZCT j .

[0254] In this example, the distribution function g(p) of the original block 200 is rotationally symmetric with respect to the axis of symmetry A of the original block 200. This implies that the zero-crossing temperature ZCT of the original block 200 is... R The distribution function g(p) is mapped onto itself for rotation about the axis of symmetry A through any desired angle (azimuth). , Figure 5 ).

[0255] Optionally, the zero-crossing temperature ZCT of the original block 200 can also be provided in step S2. R The error range Δg of the distribution function g(p).

[0256] like Figure 4 As shown, the original block 200 has, for example, a cylindrical shape 206, such as the shape of a straight cylinder 206. The original block 200, that is, the cylindrical shape 206 of the original block 200, has a cylindrical axis B corresponding to the axis of symmetry A. In addition, the original block 200 or its cylindrical shape 206 has two opposing end faces 208, 210 (e.g., circular surfaces 208, 210) and a side surface 212.

[0257] exist Figure 4 In the example, the position p of the original block 200 is described in an exemplary manner using a Cartesian coordinate system 214 based on Cartesian coordinates x', y', z' (e.g., p). j =x j y j , z j ).

[0258] Figure 5 Showing from Figure 4 The original block 200 is a plan view, and the Cartesian coordinate system 214 and the cylindrical coordinate system 216 are also shown.

[0259] like Figure 5 As explained, the position p of the original block 200 can also be expressed in cylindrical coordinate system 216 (cylindrical coordinate ρ, Instead of using Cartesian coordinates (z'), it is described using 214. Figure 5 In the example shown, the z' axes of Cartesian coordinate system 214 and cylindrical coordinate system 216 correspond to each other. Furthermore, in... Figure 5 In the Cartesian coordinate system 214, the x' axis is at... equal to zero ( =0) Aligned in the direction and angle Increase from the x' axis to the y' axis.

[0260] The radial direction r of the original block 200 ( Figure 5 Specifically along the cylindrical coordinates ρ and through the rotation angle Arranged in all directions from cylindrical coordinates ρ. Additionally, the height direction h of the original block 200 ( Figure 5 Arranged along the Cartesian and cylindrical axes z'.

[0261] Zero-crossing temperature ZCT of original block 200 R The distribution function g(p) is rotationally symmetric with respect to the axis of symmetry A of the original block 200, which implies the zero-crossing temperature ZCT of the original block 200. R With pattern 218, such as Figure 6 As shown. Specifically, pattern 218 includes concentric rings 220 (particularly circular rings 220) arranged concentrically around an axis of symmetry A. Figure 6 In the accompanying drawings, three rings 220 have been labeled with reference numerals by way of example. Furthermore, regarding the ring width 222, for clarity, in... Figure 6 The description of Ring 220 is exaggerated.

[0262] Zero Crossing Temperature ZCT R The zero-crossing temperature ZCT of the original block 200 remains unchanged along the corresponding ring 220. R The distribution function g(p) relative to the azimuth angle It has directional symmetry.

[0263] In comparison, the zero-crossing temperature ZCT of the original block 200 R It varies in the radial direction r. Furthermore, the zero-crossing temperature ZCT of the raw material block 200... R It also varies in the height direction h.

[0264] In the third step S3 of this method, the various cut regions D of the original block 200 are... i A computer-implemented inspection was performed to cut out the optical component 102 from the original block 200. Figure 2 The substrate 104.

[0265] Specifically, in step S3, the distribution function ZCT provided for the original block 200 R and the cut area D of the original block 200 i Multiple positions P that are different from each other i Each of the simulations is implemented by a computer. Specifically, the cutout region D is provided. i A total of n distinct positions P i Here, n is a natural number greater than 1, and i represents the index from 1 to n. The corresponding cut region D is determined within the simulation range. i The resulting optical component 102 and / or the optical system 100 having the corresponding optical component 102 aberration F i In other words, F i It is for the incision area D i The n provided positions P i The aberrations determined by simulation at the i-th position in the image. In other words, a total of n distinct aberrations F are determined during the simulation. i .

[0266] In other words, the zero-crossing temperature ZCT of the original block 200 provided in step S2 R The distribution function g(p) and the cut region D of the original block 200 i Multiple positions P that are different from each other iEach of the n (in total) is an input parameter for the simulation calculation in step S3. Furthermore, the determined aberration F i (A total of n) are the output parameters of the simulation calculation.

[0267] Figure 7 and Figure 8 The cut area D is shown. i Different positions P i This is used as the input variable for the simulation. Specifically, it refers to multiple locations P in the cut region D. i Determine the aberration F i These positions are at radial positions r of the original block 200. i and / or height position h i They differ in many ways.

[0268] Figure 7 It shows Figure 4 A plan view of the original block 200. Furthermore, the cut area D is shown as an example. i Two different positions P i They are relative to the radial position r i They are different from each other. In particular, the radial position r i It is the position along the radial direction r of the original block 200. Furthermore, the radial direction r extends from the axis of symmetry A of the original block 200, where the radius r0 is zero (r0=0), to the side surface 212 of the original block 200. Figure 4 The outer radius r at point ) A .

[0269] The first exemplary position P1 of the first cutting region D1 is located at a radial position r1. Furthermore, the second exemplary position P2 of the second cutting region D2 is located at a radial position r2. For example, the (e.g., geometric) centers m1 and m2 of the corresponding cutting regions D1 and D2 are located at... Figure 7 The locations P1 and P2 are marked as the corresponding incision regions D1 and D2. However, the incision region D... i Position P i It may also include the corresponding incision area D. i The positions of the outer edges 224 and 226 are r 1A r 1E ,like Figure 7 An example of the cut area D1 is shown.

[0270] n cutout regions D can be selected (i.e., arranged within the original block 200) in such a way. i Each of (e.g., D1, D2) is such that it has no axis of symmetry A. In other words, the corresponding cut region D i For example, it does not include the axis of symmetry A. That is, the cut area D. iP at each position i (For example, incision area D) i The outer edges (positions 224 and 226) are located at radii r1 and r2 respectively, which are greater than zero. Figure 7 As shown.

[0271] Replace or exclude different radial positions ( Figure 7 In addition to the above, there are multiple incision areas D. i Multiple positions P i They can also have different height positions h1 and h2, such as Figure 8 As shown.

[0272] exist Figure 8 In the example, the third exemplary position P3 of the third cut region D3 is located at the radial position r3 and the height position h3. Furthermore, the fourth exemplary position P4 of the fourth cut region D4 is located at the radial position r4 and the height position h4. Furthermore, the fifth exemplary position P5 of the fifth cut region D5 is located at the radial position r5 and the height position h5. That is, in Figure 8 In the example, cut regions D3 and D4 have the same radial positions r3 and r4 (r3=r4) but different height positions h3 and h4. Furthermore, cut regions D4 and D5 have the same height positions h4 and h5 (h4=h5) but different radial positions r4 and r5.

[0273] Figure 7 and Figure 8 The cutout region D shown and used as the input parameter for the simulation in step S3. i Position P i It should only be considered in relation to the radial position r i and height position h i Different positions P i Example. Within the original block 200, the cut area D i Regarding the radial position r i and height position h i Many other locations P i It is possible.

[0274] For example, the incision area D i Position P i It can cover the radial range Δr of the original block 200 ( Figure 7 ), which originates from the inner radius r of the axis of symmetry adjacent to A. t The outer radius r at the side surface 212 of the original block 200 A In other words, the cut area D i radial position r i It can cover the entire radial range Δr of the original block 200, except for the axis of symmetry A.

[0275] In addition to or alternatively, the incision area D i Position P i For example, it can cover the first end face 208 (h0=0) of the original block 200. Figure 8 ) to the second end face 210 (h A , Figure 8 The height range Δh of the cut area. In other words, the cut area D. i Height position h i It can cover the entire height Δh of the original block 200.

[0276] Figure 7 and Figure 8 The cut area D is shown. i Regarding the radial position r i and height position h i Different positions P i .

[0277] In addition, the incision area D i Multiple positions P i They can also differ from each other in rotation about one or more rotational degrees of freedom, for example, rotations about the x' direction (first direction), the y' direction (second direction), and / or the z' direction (third direction). In particular, the third direction z' of the original block 200 is arranged along (i.e., corresponding to) the axis of symmetry A of the original block 200. In particular, the first and second directions x' and y' are arranged to be perpendicular to each other and, in each case, perpendicular to the axis of symmetry A.

[0278] As an example, Figure 9 The positions P6 and P7 of two cut regions D6 and D7 are shown, and their rotations about x' (the first direction) are different from each other. In particular, position P6 is relative to... Figure 9 Position P7 in the middle was rotated by an angle β.

[0279] Although not shown in the figure, multiple locations P in the cut area D are present. i They can also differ from each other with respect to rotations about the y' direction (second direction) and / or the z' direction (third direction).

[0280] like Figure 7A and 8A As explained up to 8E, except for the corresponding position P i aberration F i In addition, for the corresponding incision area D i Multiple positions P that are different from each other i Each of these can also consider one or more deviation locations Q from the incision region D. qOne or more deviations E q This can account for the inaccuracies when cutting the substrate 104 from the original block 200 (step S5).

[0281] For the exemplary incision regions D1 and D2, Figure 7A The corresponding tolerance area T is shown. i =T1 and T i =T2. Furthermore, in Figure 8A The diagram shows the corresponding tolerance area T3 for the exemplary cut areas D3 to D5 (without the reference numerals for D4 and D5). Although in Figure 9 Although not shown in the diagram, corresponding tolerance areas can be set for the cut areas D6 and D7 respectively.

[0282] As in Figures 8B to 8E As exemplified in the diagram for a cut region D3 with tolerance region T3, one or more deviation locations Q corresponding to the cut region D3 can now be considered. q Specifically, the deviation position Q corresponding to the incision area D3. q The selected region is the deviation cut area C that is thus defined. q Located within the tolerance region T3. Here, q represents the index, from 1 to the deviation position Q. q total.

[0283] Figure 8B The two deviation positions Q1 and Q2 of the cut region D3 are explained. The deviation positions Q1 and Q2 differ from the position P3 of the cut region D3 in terms of displacement (Q1) in the first direction x' and displacement (Q2) in the third direction z'. Although not shown, the deviation positions may also differ from the position P3 of the cut region D3 in terms of displacement in the second direction y'.

[0284] Figure 8C Another deviation position Q3 of the incision region D3 is illustrated. The deviation position Q3 differs from the position P3 of the incision region D3 in terms of rotation about the second direction y'. Although not shown, the deviation position may also differ from the position P3 of the incision region D3 in terms of rotation about the first direction x' and / or the third direction z'.

[0285] Figure 8D Another deviation position Q4 of the cut region D3 is explained. The deviation position Q4 differs from the position P3 of the cut region D3 in terms of the non-parallel edges 230, 232 (i.e., outer edges) of the deviation cut region C4 in the first direction x'. Although not shown, the edges of the deviation cut region may also be non-parallel in the second direction y' and / or the third direction z'.

[0286] Figure 8EAnother deviation position Q5 of the incision region D3 is explained. The deviation position Q5 differs from the position P3 of the incision region D3 in terms of the volume deviation ΔW (e.g., ΔW = W2 – W1) between the deviation incision region C5 and the incision region D3. Other volume deviations (e.g., in other directions x', y', z') can also be considered.

[0287] ( Figures 8B to 8E The deviation position Q shown and / or all types described herein. i (e.g., Q1 to Q5) and deviation incision area C i (For example, C1 to C5) can be combined with each other as needed to generate additional deviation positions Q. i and deviation incision area C i .

[0288] Next, we can target each incision area D. i (That is, for each deviation cut area C) i Each considered deviation position Q i (For example, Q1 to Q5) Determine the corresponding deviation aberration Ei.

[0289] Then, at least one selected location P of the cut area D can be selected. a It was determined to be from multiple locations P i At a given location, the determined aberration F i and one or more determined deviation aberrations E q (For example, E1 to E5) are each less than the predetermined threshold SW ( Figure 9A ).

[0290] Alternatively, in step S3, the error can be based on multiple individual errors f that are different from each other. k Determine each error F i (and each error E) q (if applicable) Figure 10 Specifically, multiple individual errors f are associated with different error types in the imaging process of the optical system 100. k It can be used to determine each error F i (and each error E) q (if applicable).

[0291] For example, individual errors f that are different from each other k Considered as a relative error value. In this variation of step S3, the error F of the imaging process of the optical system 100 is... i (and error E) q (If applicable) For example, it can be determined as a number of specific individual errors f k The maximum value, for example, based on the following equation:

[0292] F i =max(f k ), where i = 1 to n and k = 1 to m

[0293] In this case, f k This represents the provided distribution function g(p) and the specific location P of the cut region D. i The (e.g., relative) individual errors. In this case, k is an index from 1 to m, where m is a natural number greater than 1, representing the individual errors f that are distinct from each other. k The total number.

[0294] In other examples, the error F in the imaging process of optical system 100 i Alternatively, it can be determined in step S3 as a plurality of specific individual errors f k The mean, median, and / or quantiles.

[0295] Multiple individual errors f that are different from each other k This can involve, for example, the actual focal point F of optical system 100. Ist With target focus F Soll Deviations (defocus, spherical aberration, Zernike polynomial ZP of Z²), such as Figure 10 As shown. Figure 10 The incident light on the optical system 100 is shown. Figure 2 The radiation 300 on the image plane 302 (e.g., Figure 1 (Operating light 16 in the image). Specifically, the target focus F. Soll Located in image plane 302. Actual focal point F. Ist Deviation from target focus F Soll Therefore, the image is blurry. The actual focus F... Ist With target focus F Soll The deviation represents the individual error f. k Examples include the first (k=1) individual error f1.

[0296] also, Figure 10 The error range ΔF was plotted. fokus As a threshold SW ( Figure 9A Examples of () and / or individual thresholds. For example, within range F Soll ±ΔF fokus The actual focal point within is the aberration F less than the threshold SW. i .However, Figure 10 The actual focus F shown Ist No longer in range F Soll ±ΔF fokus Therefore, the corresponding incision area D is... i Relevant position Pi The selection of position P is not satisfied. a The conditions. The error range ΔF corresponding to the individual thresholds of threshold SW and / or focus. fokus Exemplary values ​​include, for example, 15 nm or less, 10 nm or less, and / or 5 nm or less.

[0297] For example, multiple individual errors f that are different from each other. k It can also be associated with wavefronts (e.g.) Figure 10 The displacement of 304 in the image plane 302 of the optical system 100 relative to the target wavefront 306 is related to the displacement of 304 in the image plane 302 of the optical system 100. Figure 10 Image 400 in ) Figure 11 The actual position P of object 402 in the image. Ist Target position P, 404 away from the imaged object Soll ,like Figure 11 As shown. Actual position P Ist With target location P Soll The deviation (overlap error) represents the individual error f. k Another example is the second (k=2) individual error f2.

[0298] In addition to or replacing individual errors f that are related to different error types from each other. k In addition, there are multiple individual errors f that are different from each other. k Individual errors f, which differ from each other, can also be related to the illumination setting parameters of the optical component 102 to be manufactured in the optical system 100. k Related.

[0299] For example, the various setting parameters of the planned illumination for the optical component 102 to be manufactured include the operating light (e.g., EUV light 16) radiated onto the optical component 102. Figure 1 The radiation intensity of ).

[0300] For example, various lighting settings may also include pattern 500 or heat flux distribution 500, with the operating light 16 radiating onto the optical component 102 in pattern 500 or heat flux distribution 500. For example, Figure 12 The optical components (e.g.) are explained Figure 2 The optical effective surface 506 of the optical component 102) has two heat flux poles 502 and 504 (dipole pattern) for the heat flux distribution 500.

[0301] In addition to or replacing individual errors f that are related to different error types from each other. k In addition, there are multiple individual errors f that are different from each other. kIndividual errors f, which can also be different from each other, can be related to the setting parameters 604 of the heating of the optical component 102 to be manufactured by the external heating device 600. k Related. Figure 12A It clarified Figure 2 The optical component 102 has a substrate 104 and an optically effective surface 106. Furthermore, Figure 12A An external heating device 600 for heating optical components 102 is shown. For example, the external heating device 600 includes a plurality of radiation heaters 602. Two radiation heaters 602 are in... Figure 12A The figure is shown by way of example; however, more than two radiant heaters 602 may also be provided. An array of radiant heaters may also be provided. Furthermore (although not shown in the figure), the heating device 600 may also be configured to heat the optical component 102 by heat conduction, rather than by heating radiation, i.e., thermal radiation, as shown.

[0302] Heating of the optical component 102 to be manufactured by the external heating device 600 can be achieved according to various setting parameters 604 of the heating device 600. For example, the various setting parameters 604 include the optical component 102 (or its area, see...) Figure 12B The temperatures T1 and T2 are to be heated. For example, various setting parameters 604 also include a heating pattern 606 used during heating. In particular, the heating pattern 606 is a temperature pattern that should be implemented in the optical component 102. In particular, the heating pattern 606 is a target temperature map related to two-dimensional or three-dimensional space of the optical component 102. In particular, when determining an individual error f k Various heating patterns 606 to be applied can be considered. A suitable heating pattern 606 is selected such that it is suitable for correcting a specific type of error in the imaging process. The extent to which a specific error type can be corrected by a heating pattern 606 adapted for this purpose depends particularly on the distribution of the zero-crossing temperature ZCT of the substrate 104. For example, the compression temperature domain lies between the ambient temperature and approximately twice the temperature difference between the ambient temperature and the zero-crossing temperature ZCT in the spatial region of the substrate 104 in which compression is to be applied. For example, the expansion temperature domain extends from the compression temperature domain into a warmer temperature region. The size of these temperature domains, especially the size of the compression temperature domain, determines the correction potential for one or more error types in the imaging process by heating with an external heating device 600.

[0303] Figure 12B An exemplary heating pattern 606 is shown via an external heating device 600 ( Figure 12A An example of a planned heating of the optical component 102 to be manufactured. For example, Figure 12BThe example of the heating pattern 606 shown is used to correct Zernike Z20 aberrations and / or aberrations according to the Zernike polynomial Z 5, ±3. The heating pattern 606 has three regions 608 (sectors 608) with a first target temperature T1 and three regions 610 (sectors 610) with a second target temperature T2. Specifically, the first target temperature T1 is the temperature at which the material of the optical component 102 is locally compressed. Furthermore, specifically, the second target temperature T2 is the temperature at which the material of the optical component 102 is locally expanded. By heating according to the heating pattern 606, regions 608 are compressed and regions 610 are expanded. Therefore, the optical component 102 deforms in a manner that achieves the desired wavefront effect to correct the corresponding aberrations.

[0304] Figure 12B The heating pattern 606 in the diagram is only for illustrating the use of Figure 12A An example of heating by the heating device 600. Instead of heating pattern 606, or in addition to heating pattern 606, a separate error f can be implemented by a computer. k The determination process takes into account any other heating patterns suitable for aberration correction.

[0305] Although not shown in the accompanying drawings, multiple determined individual errors f can be weighted according to predetermined weights. k Weighting is performed. As a result, the individual error f can be weighted according to the optical component 102 to be manufactured and the intended use of the optical system 100 having the component 102. k .

[0306] For example, in order to determine the aberration F in step S3 i (and bias aberration E) q (If applicable), the following adjustment functions can be applied:

[0307]

[0308] Here, W ref This represents the reference wavefront. For example, the reference wavefront contains a vector of Zernike coefficients, which are based solely on the cut region D. i Position P i radial displacement ( Figure 7 ) and height displacement ( Figure 8 (i.e., no rotation) Figure 9 The illumination settings (thermal load conditions) of the optical system 100 are determined for the cut area D. For example, a reference wavefront containing a vector of Zernike coefficients is used, which also takes into account the time series of the use of the optical components 102 of the optical system 100.

[0309] In addition, sensitivity is defined as follows:

[0310]

[0311] Here, W(p) l ) indicates that if the cut area D is selected i Also consider rotations 228 around the first, second, and / or third axes x', y', z' of the original block 200. Figure 9 The wavefront is obtained by [the process of] ). Index l represents various optimization cases, such as rotations 228 around the first, second, and / or third axes x', y', z' of the original block 200. Figure 9 ), radial displacement ( Figure 7 ) and height displacement ( Figure 8 ).

[0312] However, in other examples, a different adjustment function than the one described above may be applied in step S3.

[0313] In the fourth step S4 of this method, the incision area D is... i At least one selected position P a Determined to be multiple locations P i The determined aberration F in i The position is less than the predetermined threshold SW.

[0314] Figure 9A This is illustrated through examples. Figure 9 The aberration F of the cut region D6 (for i=6) in the image i =F6. From Figure 9A It can be clearly seen that the aberration F6 of the incision region D6 is less than the predetermined threshold SW. Therefore, in this example, the position P6 of the incision region D6 is determined as at least one selected position P in step S4. a .

[0315] like Figure 9A As shown, in the corresponding aberration F i (and the corresponding bias aberration E) q During the determination period implemented by the computer (if applicable), the determined aberration F may optionally be further determined. i Error range ΔF i In this case, at least one selected location P of the incision region D. a It can be determined that it comes from multiple locations P i At a given location, the determined aberration F i (including its error range ΔF) i The value is less than the predetermined threshold SW. Figure 9AIn the example, the aberration F6 of the incision region D6, including its error range ΔF6, is less than a predetermined threshold SW. Specifically, F6 ± ΔF6 is less than the predetermined threshold SW.

[0316] If the selection location P of the incision area D is not determined in step S4 a Because the determined aberration F i If none of the values ​​are less than a predetermined threshold SW, then it can be determined, for example, that the original block 200 is not suitable for manufacturing the substrate 104. In this case, step S5 is not performed.

[0317] Optionally, the incision area D i At least one selected position P a It could also be the incision area D. i Optimal position P opt To achieve minimum aberration F i —Instead of, or in addition to, based on the threshold SW. In other words, the cut area D i Optimal position P opt It can also be determined as multiple locations P in step S4. i The aberration F determined in i The smallest position.

[0318] For example, multiple error values ​​F of the imaging process of the optical system 102 determined in step S3. i The minimum value is determined as the final error F. E :

[0319] F E =min(F i For i=1 to n

[0320] Here, n is a natural number greater than 1, and represents the aberration F determined in step S3. i The quantity. Furthermore, i is an index from 1 to n.

[0321] Subsequently, the incision area D i The minimum value F E Associated location P i The cutout region D of the substrate 104, which is identified as being used to manufacture the optical component 102, is... i Optimal position P opt .

[0322] For example only, Figure 9 The position P shown i =P6 is marked as such a position, the associated determined individual error F of which i =F6 was determined to be for all provided positions P i All determined individual errors Fi The minimum error F in E Therefore, in this example, the location P6 associated with the individual error F6 is determined to be the cut area D. i Optimal position P opt .

[0323] In the fifth step S5 of this method, based on the incision area D... i At least one definite selection position P a and / or incision area D i Optimal position P opt From the original block 200 ( Figure 4 Cut out substrate 104 ( Figure 2 ).

[0324] To manufacture the substrate 104 of the optical component 102, the method allows for the selection of a cutout region D (i.e., at least one selected location P of the cutout region D) based on an advantageously and / or optimally determined cutout region D. a and / or optimal position P opt A cut-out area is created from the blank 200. In particular, a cut-out area D with a favorable distribution of zero-crossing temperature ZCT can be selected. As a result, the aberration F of the optical system 100 caused by the thermal expansion of the substrate 104 can be reduced.

[0325] Figure 13 An example of a substrate 104' of the optical component 102 of the optical system 100 of the display lithography apparatus 1, which is manufactured based on the method described above. The substrate 104' includes a distribution function g'(p') of the zero-crossing temperature ZCT' of the coefficient of thermal expansion α' as a function of the position p' of the substrate 102'. Furthermore, the distribution function g'(p') includes a pattern 112 of the zero-crossing temperature ZCT', which includes a plurality of concentric ring segments 114, each of which is a partial segment of a complete ring 116 in each case.

[0326] Figure 13 Tangents T of loop segment 114 are shown, with tangents T arranged parallel to each other. Furthermore, one of the virtual complete loops 116 of one of the loop segments 114 is indicated by dashed lines. Additionally, reference numeral 118 marks the virtual center of the complete loop 116. Figure 13 Auxiliary lines 120 (or auxiliary directions 120) for substrate 104' are also drawn. The auxiliary lines 120 for substrate 104' are defined such that they are arranged perpendicular to the tangent T and pass through the virtual center 118 of the concentric complete ring 116 corresponding to ring segment 114. Figure 13 In the example, the auxiliary line 120 is arranged parallel to the longitudinal direction L of the substrate 104'.

[0327] Figure 13The substrate 104' shown is manufactured based on the method described above (i.e., cut from the original block 200), wherein the substrate is cut in the radial direction r ( Figure 7 ) and height direction h ( Figure 8 The position of the upper displacement incision area D P i To select the optimal location P for the incision area D opt .

[0328] Figure 14 Another example of a substrate 104'' of the optical component 102 of the optical system 100 of the photolithography apparatus 1 is shown, which is manufactured based on the method described above. Figure 14 In the example, except for the location P of the cut area D. i In addition to displacement in the radial direction r and the height direction h, it is also achieved by performing a 200S rotation around the billet. Figure 9 The first, second, and / or third rotations of x', y', z' in the first, second, and / or third directions, 228, are based on the optimal position P of the cut area D. opt The choice is to manufacture substrate 104''.

[0329] With similar Figure 13 The way, for Figure 14 Applicable to this designation, the reference numeral T'' denotes the tangent of segment 114'', wherein the tangents T'' are arranged parallel to each other. Furthermore, Figure 14 A virtual complete ring 116'' of one of the ring segments 114'', a virtual center 118'' of the complete ring 116'', and an auxiliary line 120'' (or auxiliary direction 120'') of the substrate 104'' were also drawn. Figure 14 The auxiliary line 120'' of the substrate 104'' is like Figure 13 The auxiliary line 120 is defined in the same way, specifically such that the auxiliary line 120'' is arranged perpendicular to the tangent T'' and passes through the virtual center 118'' of the concentric complete loop 116'' corresponding to the loop segment 114''. (Similar to...) Figure 13 Unlike other examples, the auxiliary line 120'' of substrate 104'' is arranged at a certain angle to the longitudinal direction L'' of substrate 104''.

[0330] Although the invention has been described based on exemplary embodiments, it can be modified in various ways.

[0331] List of reference numerals

[0332] 1. Projection Exposure Equipment

[0333] 2 Lighting System

[0334] 3 light sources

[0335] 4 Illumination Optical Units

[0336] 5 objects

[0337] 6 object plane

[0338] 7 Mask Master

[0339] 8 Mask Master Retainer

[0340] 9 Mask Master Displacement Driver

[0341] 10 projection optical units

[0342] 11 Image Field

[0343] 12 Image plane

[0344] 13 chips

[0345] 14. Chip Holder

[0346] 15. Wafer displacement driver

[0347] 16. Lighting radiation

[0348] 17 light collector

[0349] 18. Intermediate focal plane

[0350] 19 Deflecting mirrors

[0351] 20 First faceted mirror

[0352] 21 First facet

[0353] 22 Second faceted mirror

[0354] 23 Second facet

[0355] 100 Optical System

[0356] 102 Optical Components

[0357] 104, 104', 104'' substrate

[0358] 106 optically effective surface

[0359] 108 Materials

[0360] 110 main body

[0361] 112 pattern

[0362] 114, 114'' ring segments

[0363] 116, 116'' Complete ring

[0364] 118, 118'' Center

[0365] 120'' auxiliary lines

[0366] 200 billet

[0367] 202 Materials

[0368] 204 Main Body

[0369] 206 Cylindrical shape

[0370] 208 surface

[0371] 210 surface

[0372] 212 surface

[0373] 214 coordinate system

[0374] 216 Coordinate System

[0375] 218 Pattern

[0376] 220 rings

[0377] 222 width

[0378] 224 Edge

[0379] 226 Edge

[0380] 228 rotations

[0381] 230 Edge

[0382] 232 Edge

[0383] 300 radiation

[0384] 302 Image Plane

[0385] 304 Actual wavefront

[0386] 306 Target Wavefront

[0387] 400 images

[0388] 402 Object

[0389] 404 Object

[0390] 500 Heat flux distribution

[0391] 502 heat flux

[0392] 504 heat flux extreme

[0393] 506 Optical Effective Surface

[0394] α, α', α'' thermal expansion coefficients

[0395] α R coefficient of thermal expansion

[0396] Axis A

[0397] β angle

[0398] B axis

[0399] C q Deviation incision area

[0400] C1-C5 Deviation Cutting Area

[0401] D incision area

[0402] D i Incision area

[0403] D1-D7 incision area

[0404] ΔF i ΔF6 error range

[0405] ΔF Fokus Error range

[0406] Δg error range

[0407] Δh Height range

[0408] Δr Radial range

[0409] ΔW volume deviation

[0410] ΔZCT temperature difference

[0411] ΔZCT R Temperature difference

[0412] E q Deviation

[0413] E1-E5 Deviations and Aberrations

[0414] F error

[0415] F i error

[0416] F1-F6 error

[0417] f k error

[0418] F Ist Actual focus

[0419] F Soll Target Focus

[0420] functions g, g', g''

[0421] h height

[0422] h1–h5 height

[0423] h0, h A high

[0424] L, L'' direction

[0425] total m

[0426] m1, m2 center

[0427] M average

[0428] M R average value

[0429] M1-M6 reflectors

[0430] n total

[0431] p, p', p'' position

[0432] p j Location

[0433] Positions P1-P7

[0434] P a Select location

[0435] P i Location

[0436] Positions P1-P7

[0437] Q q Deviation position

[0438] Q1-Q5 deviation positions

[0439] r direction

[0440] r0、r i r t radius

[0441] radius of r1-r5

[0442] r 1A r 1E radius

[0443] ρ cylindrical coordinates

[0444] Cylindrical coordinates (angles)

[0445] S1-S5 Method Steps

[0446] SW threshold

[0447] T, T'' Tangent

[0448] T i Tolerance area

[0449] T1-T3 tolerance area

[0450] V j Volume elements

[0451] Volumes of W1 and W2

[0452] x j , y j , z j Location (coordinates)

[0453] x, y, z directions

[0454] x', y', z' directions

[0455] x'', y'', z'' directions

[0456] ZCT zero-crossing temperature

[0457] ZCT', ZCT'' zero-crossing temperature

[0458] ZCT j Zero crossing temperature

[0459] ZCT R Zero crossing temperature

Claims

1. A method for manufacturing an optical system (100) for a photolithography apparatus (1), the optical system (100) comprising an optical component (102) having an optical substrate (104) cut from a raw block (200), the method comprising the steps of: a) Provides (S2) the coefficient of thermal expansion (α) of the original block (200) as a function of the position (p) of the original block (200). R The zero-crossing temperature (ZCT) R The distribution function (g) of the original block (200) is rotationally symmetric about the axis of symmetry (A) of the original block (200). b) Determine (S3) the aberrations (F) of the optical system (100) using a computer-implemented method. i ), for the provided distribution function (g) and multiple locations (P) of the cut region (D) of the original block (200). i Each of the multiple locations in the incision region (D) is different from each other, wherein the multiple locations (P) of the incision region (D) are... i ) with respect to the radial position (r) of the original block (200) i ) and / or altitude position (h i They are different from each other, and c) Determine at least one selected location (P) of the incision region (D) as described in (S4). a ) as the multiple locations (P) i The aberrations (F) determined in ) i The position is less than the predetermined threshold (SW).

2. The method according to claim 1, wherein, In step c), the optimal position (P) of the incision area (D) is determined. opt ) is determined as the plurality of locations (P) i The aberrations (F) determined in ) i The smallest position.

3. The method according to claim 1 or 2, wherein, The cut area (D) does not have the axis of symmetry (A).

4. The method according to any one of claims 1 to 3, wherein, The original block (200) has a cylindrical shape (206), the cylindrical shape having a cylindrical axis (B) corresponding to the axis of symmetry (A) and a side surface (212), and The radial position (r) of the original block (200) i ) is the position along the radial direction (r) of the original block (200), wherein the radial direction (r) extends from the zero radius (r0) at the axis of symmetry (A) to the outer radius (r) at the side surface (212). A ).

5. The method according to any one of claims 1 to 4, wherein, The plurality of locations (P) of the incision region (D) i The radial range (Δr) covering the original block (200) extends from the inner radius (r) adjacent to the axis of symmetry (A). t The outer radius (r) from the side surface (212) of the original block (200) to the outer radius (r) A ), and / or The plurality of locations (P) of the incision region (D) i The height range (Δh) of the original block (200) from the first end face (208) to the second end face (210) of the original block (200) is covered.

6. The method according to any one of claims 1 to 5, wherein, The original block (200) has a first direction, a second direction, and a third direction (x', y', z'). The third direction (z') is arranged along the axis of symmetry (A) of the original block (200). The first direction and the second direction (x', y') are arranged perpendicular to each other and in each case perpendicular to the axis of symmetry (A), and The plurality of locations (P) of the incision region (D) i ) with respect to the radial position (r) of the original block (200) i ) and / or altitude position (h i The rotations (228) about the first direction, the second direction and / or the third direction (x', y', z') are different from each other.

7. The method according to any one of claims 1 to 6, wherein, In addition to the corresponding incision area (D) i The corresponding position (P) i aberrations (F) i In addition to the above, it also targets multiple locations (P) that are different from each other in the incision area (D). i Each of the points in the diagram determines one or more deviation locations (Q) from the incision region (D). q One or more deviations (E) q ), Select one or more deviation locations (Q) q ), thus defining one or more deviation cut regions (C q ) is located at the corresponding position (P) i The corresponding incision area (D) defined by ) i The tolerance area around (T) i Inside, and The at least one selected location (P) of the incision area (D) a ) is determined as the plurality of locations (P) i At a given location, the determined aberration (F) i ) and one or more determined deviation aberrations (E q Each of them is less than the predetermined threshold (SW).

8. The method according to claim 7, wherein, The original block (200) has a first direction, a second direction, and a third direction (x', y', z'). The third direction (z') is arranged along the axis of symmetry (A) of the original block (200). The first direction and the second direction (x', y') are arranged perpendicular to each other and in each case perpendicular to the axis of symmetry (A), and The one or more deviation locations (Q) q ) and the corresponding incision area (D) i The corresponding position (P) i They differ in the following aspects: The radial position (r) i ), The height position (h) i ), Displacement in the first direction, the second direction, and / or the third direction (x', y', z'), Rotation about the first, second, and / or third direction (x', y', z'), The non-parallel edges (230, 232) of the deviation cut region (C4), in each case, are along the first direction, the second direction, and / or the third direction (x', y', z'), and / or The one or more deviation incision areas (C5) and the corresponding positions (P) i The corresponding incision area (D) defined by ) i Volume deviation (ΔW).

9. The method according to any one of claims 1 to 8, wherein, The corresponding aberrations (F) in the optical system (100) i During the determination period implemented by the computer, the determined aberrations (F) are additionally determined. i The error range (ΔF) i ), and the at least one selected location (P) of the incision region (D) a ) was determined to be one of the plurality of locations (P) i The following positions in the diagram: For this position, the determined aberration (F) i This includes its error range (ΔF). i The value is less than the predetermined threshold (SW).

10. The method according to claim 9, wherein, The corresponding aberrations (F) are determined by means of computer-based simulation. i ), and determine the determined aberration (F) based on one or more error ranges (Δg) of one or more input parameters (g) of the simulation. i The error range (ΔF) i ).

11. The method according to claim 9 or 10, wherein, Based on the provided zero-crossing temperature (ZCT) R The error range (Δg) of the distribution function (g) is used to determine the determined aberration (F). i The error range (ΔF) i ).

12. The method according to any one of claims 9 to 11, wherein, The corresponding aberrations (F) are determined by means of computer-based simulation. i ), and determine the determined aberration (F) based on taking into account one or more systematic errors of the simulation. i The error range (ΔF) i ).

13. The method according to any one of claims 1 to 12, wherein, The corresponding aberration (F) of the optical system (100) i The determination of ) includes: Identify multiple distinct individual errors (f) that are associated with different error types of the optical system (100). k ),as well as Based on multiple determined individual errors (f) k ) Determine the corresponding aberration (F) of the optical system (100) i ).

14. The method according to claim 13, wherein, The multiple individual errors (f) that are different from each other are determined by the setting parameters (500) of the optical component (102) to be manufactured, which illuminate the optical system (100) with different operating lights (16). k ).

15. The method according to claim 13 or 14, wherein, The multiple individual errors (f) that are different from each other k The different setting parameters (604) for the heating of the optical component (102) to be generated by the external heating device (600) are determined.

16. The method according to claim 15, wherein, Heating the optical component (102) to be manufactured by the external heating device (600) includes heating according to a heating pattern (606) or multiple different heating patterns (606), which are correspondingly adapted to correct one or more of various error types, and determining multiple individual errors (f) that are different from each other relative to the one heating pattern (606) or the multiple heating patterns (606) that are different from each other. k ).

17. The method according to any one of claims 13 to 16, wherein, Regarding the different error types, multiple determined individual errors (f k )include the following: The actual focal point (F) of the optical system (100) Ist ) and target focus (F Soll The deviation (f1) of ) The actual position (P) of the object (402) imaged in the image plane (302) of the optical system (100) by means of the optical system (100) Ist ) and the target position (P) of the imaged object (404) Soll deviation, Image displacement of the image (400) formed in the image plane (302) of the optical system (100) by means of the optical system (100), and / or The deviation between the actual wavefront (304) and the target wavefront (306) of the image (400) imaged in the image plane (302) of the optical system (100).

18. The method according to claim 17, wherein, The deviation between the actual wavefront (304) and the target wavefront (306) includes the tilt of the wavefront (304), the displacement of the wavefront (304), the astigmatism of the wavefront (304), the coma of the wavefront (304), the higher-order (n) foil aberrations of the wavefront (304) and / or the spherical aberrations of the wavefront (304), and / or The deviation between the actual wavefront (304) and the target wavefront (306) is quantified in the form of a Zernike polynomial (ZP).

19. The method according to any one of claims 1 to 18, comprising: Provide (S1) the original block (200), and The zero-crossing temperature (ZCT) of the original block (200) is measured (S2). R The distribution function (g) of ).

20. The method according to any one of claims 1 to 19, comprising: Provide (S1) the original block (200), and Based on at least one determined selection location (P) of the incision region (D) a ) and / or the optimal location (P) of the cut area (D). opt (S5) The substrate (104) is cut out from the original block (200).

21. A substrate (104, 104', 104'') of an optical component (102) of an optical system (100) for a photolithography apparatus (1), comprising a distribution function (g', g'') of the zero-crossing temperature (ZCT', ZCT'') of the coefficient of thermal expansion (α', α'') as a function of the position (p', p'') of the substrate (104', 104''), the distribution function (g', g'') having a pattern (112, 112'') of the zero-crossing temperature (ZCT', ZCT''), the pattern comprising a plurality of concentric ring segments (114, 114''), the plurality of concentric ring segments being, in each case, partial segments of a complete ring (116, 116'').

22. The substrate according to claim 21, wherein, The auxiliary lines (120, 120'') of the substrate (104', 104'') are defined such that the auxiliary lines (120, 120'') are arranged perpendicular to mutually parallel tangents (T, T'') at the ring segments (114, 114'') and pass through the virtual center (118, 118'') of the virtual complete rings (116, 116'') corresponding to the ring segments (114, 114''). The auxiliary line (120) is arranged parallel to the longitudinal direction (L) of the substrate (104'), or The auxiliary direction (120'') is arranged at an angle to the longitudinal direction (L'') of the substrate (104'').

23. A photolithography apparatus (1), comprising: The substrate (104, 104', 104'') according to claim 21 or 22, and / or An optical system (100) has an optical component (102) having a substrate (104, 104', 104'') according to claim 21 or 22.

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