Optical component and semiconductor technology system with heating structures

Abstract

The invention relates to an optical component, in particular a mirror, comprising at least one heating structure (25, 25a) to which electric current can be applied, in particular a resistance heating structure, for introducing a heat input into a material of the optical component. The at least one heating structure (25) extends substantially over the entire optical surface (27) of the optical component and has a locally varying electrical resistance (Ra(x,y)), which preferably approaches a base function extending substantially over the entire optical surface (27), in particular a Zernike polynomial, wherein the heating structure (25) is in the form of an electrical conductor track (37) or at least two partial structures of the heating structure (25) are in the form of at least two electrical conductor tracks (37.1 to 37.n), wherein the locally varying electrical resistance (Ra(x,y)) of the heating structure (25) is generated by a locally varying electrical resistance (Ra.1 to Ra.n) of the electrical conductor track (37) or of the at least two electrical conductor tracks (37.1 to 37.n), and in which the electrical resistance (Ra.1 to Ra.n) of the electrical conductor track (37) varies in a location-dependent manner along sections (37.1 to 37.n) of the conductor track (37) extending in parallel or in which the electrical resistance (Ra.1 to Ra.n) varies in a location-dependent manner along the at least two electrical conductor tracks (37.1 to 37.n) extending in parallel.

Description

[0001] Stuttgart, October 14, 2025 SZ00376PCT Rp / pt

[0002] Optical component and system of semiconductor technology with heating structures

[0003] Reference to related registration

[0004] This application claims priority over German patent application DE 102024210679.8 dated November 7, 2024, the entire disclosure of which is incorporated by reference into this application.

[0005] Background of the invention

[0006] The invention relates to an optical component, in particular a mirror, comprising: at least one heating structure, in particular a resistance heating structure, which can be subjected to an electric current, for introducing heat into a material of the optical component. The invention also relates to a semiconductor technology system, in particular an EUV lithography system, which has at least one such optical component.

[0007] Modern semiconductor technology systems, particularly EUV lithography systems, operate with useful radiation in the EUV wavelength range, typically around 13 nm or less. In this wavelength range, there are no practically applicable refractive materials, so EUV lithography systems are designed as purely mirror systems. At wavelengths in the EUV range, EUV mirrors used to reflect the useful radiation, based on the Bragg reflection mechanism, absorb more than 30% of the incident useful radiation. Even in designs specifically optimized for transmission, other types of EUV mirrors absorb at least 15% of the incident useful radiation in typical cases where constraints such as limited installation space are considered.

[0008] 2023P00638WO 14.10.2025 SZ00376PCT In refractive media with an antireflective coating, as used at longer wavelengths, the absorbed intensity is in the parts-per-thousand range by comparison. This explains the significantly greater temperature changes in EUV optics compared to predecessor systems where the useful radiation had longer wavelengths. The temperature changes in EUV optics are on the order of several Kelvin, whereas previously they were at most a few tenths of a Kelvin.

[0009] Since temperature gradients translate into surface defects due to the thermal expansion coefficient of the optical component's material, these lead to significant optical aberrations, especially in mirrors, which degrade image quality relative to the useful wavelength. Accordingly, EUV mirrors are manufactured from materials with particularly low coefficients of thermal expansion, such as glass ceramics like Zerodur or titanium-doped quartz glass, for example, ULE ("ultra-low expansion" material). Such materials effectively counteract components with positive and negative coefficients of thermal expansion. The result is a non-linear relationship between thermal expansion and temperature, with precisely one temperature value at which thermal expansion vanishes: the zero-crossing temperature.

[0010] During operation, an EUV mirror is exposed to varying irradiance intensities, both spatially due to different illumination settings and diffraction patterns on the mask, and temporally due to different operating modes. Despite the use of materials with a low coefficient of thermal expansion, a resulting surface deformation cannot be completely avoided and should be compensated for to prevent a reduction in optical imaging performance.

[0011] 2023P00638WO 14.10.2025 SZ00376PCT deteriorate. Wavefront manipulators can be used, in particular, for compensation.

[0012] Wavefront manipulators for semiconductor lithography systems include, among others, the following elements: elements that can be moved in the direction of light or perpendicular to it, elements that can be rotated about the direction of light or about axes perpendicular to it, deformable elements, locally heated and / or cooled elements, plates that can be moved relative to each other, possibly aspherized, and interchangeable elements.

[0013] For operation in the EUV wavelength range, locally deformable mirrors are of interest as adaptive elements. These local deformations can be induced, for example, thermally, with magnetostrictively deformable elements, with thermally controlled shape memory alloys, or with piezoelectrically deformable elements. Thermally operated adaptive mirrors can be equipped with resistance heaters or resistance heating structures in addition to the well-known radiation-based heating principles.

[0014] German patent W02009026970A1 describes an adaptive optical element with resistance heaters arranged in an array of heating zones. Each heating zone has its own connection or lead and can be individually controlled. The electrical voltages of each connection, which—in the case of a single structured metallic layer—typically run in gaps between the heating zones, generally differ from those of the heating zones along their path. The resistances of the leads within a heating zone are generally chosen to be higher than the resistances of the connections to minimize uncontrolled parasitic ohmic heat input or crosstalk due to the connections. This usually results in insufficient heat being introduced into the material in the connection area, which can lead to problems.

[0015] 2023P00638WO 14.10.2025 SZ00376PCT Uniform heating in the heating zones leads to a hilly temperature profile, since heat from all directions flows together in the center of each heating zone, while heat is lacking in the area around the connections at the edge of the heating zone. Such a hilly temperature profile normally deviates systematically from the target temperature profile, which usually has a smooth, continuous curve.

[0016] To smooth the temperature profile, DE102019202 531 A1 proposes using an optical correction element with a thermal actuator, which has at least one heating zone and one connection, wherein at least two sections of the heating zone are configured to achieve different heating power densities during operation. In this way, a smoothing of the temperature profile can be achieved, although undesirable residual errors may still remain.

[0017] Object of the invention

[0018] The object of the invention is to provide an optical component and a semiconductor lithography system which enable the smoothing of a temperature profile on an optically used surface of the optical component.

[0019] Subject matter of the invention

[0020] This task is solved, according to a first aspect, by an optical component of the type mentioned above, in which the heating structure and another, adjacent heating structure have interlocking edge structures, wherein a heating power density of the edge structures of the heating structure on a side facing the other heating structure is smaller than on a side facing away from the other heating structure and / or wherein a

[0021] 2023P00638WO 14.10.2025 SZ00376PCT Heating power density of the edge structures of the further heating structure on a side facing the heating structure of the edge structures of the further heating structure is smaller than on a side facing away from the heating structure of the edge structures of the further heating structure.

[0022] In this aspect of the invention, the heating structure and the further heating structure can be supplied with electric current independently of each other. However, the edge structures of the heating structure cannot be supplied with current independently of the rest of the heating structure. The same applies to the edge structures of the further heating structure. In order to nevertheless be able to vary the heating power locally at the edge structures, the edge structures of the heating structure and / or the further heating structure have a locally varying heating power density. The rest of the heating structure, which is also referred to below as the core structure, can also have a locally varying heating power density, as described in DE102019202 531A1, but this is not mandatory; that is, the heating power density of the core structures can be essentially or on average constant.

[0023] This aspect of the invention proposes achieving a smoother temperature distribution by providing two adjacent heating structures with interlocking edge structures. In a transition zone between the two heating structures, this allows for averaging of the heating power outputs of both structures. The interlocking edge structures of the two heating structures can, for example, be interlocked or nested within one another.

[0024] It is advantageous if the contribution of each boundary structure to the local heating output decreases relative to the heating output of the other boundary structure as the boundary structure gets closer to the other heating structure, i.e., as the boundary structure approaches the other heating structure on its side.

[0025] 2023P00638WO 14.10.2025 SZ00376PCT has a lower heating power density than its side facing away from the other edge structure.

[0026] In one embodiment, the edge structures of the heating structure and the edge structures of the other heating structure interlock in a preferably strip-shaped transition region between the two heating structures. In this case, both heating structures typically have core structures from which, or from whose edges, the edge structures extend into the transition region. Unlike the edge structures, two adjacent heating structures do not interlock at the core structures. The core structures can substantially completely cover a respective surface area and generally have a predefined geometry, which can, for example, be in the form of a regular polygon, such as a hexagon or a rectangle, since these allow for the tiling of a surface with identical elements.The aspect of tiling with identical elements becomes less important when a variation in the size of the core structures is intended to ensure particularly high resolution in selected areas without unnecessarily increasing the number of leads and connections to the outside world, as would be the case if all core structures had the smallest possible area. The transition zone, which is usually strip-shaped, between the two core areas of the heating structures can have a constant width, but this is not strictly necessary. The connections for supplying the heating structures with electrical current also typically run through this transition zone, provided the heating structures are located in only one conductor layer.

[0027] In a further embodiment, the heating power density of the edge structures of the heating structure decreases, at least on average, starting from an edge of the transition region facing the heating structure, and / or the heating power density of the edge structures of the further heating structure decreases

[0028] 2023P00638WO 14.10.2025 SZ00376PCT starting from an edge of the transition region facing the other heating structure, at least on average. In this embodiment, the edge structures of the respective heating structure emit less heating power, at least on average, the closer they are to the side of the transition region facing away from the respective heating structure or to the core structure of the other heating structure. It is possible that the heating power density of the edge structures decreases continuously starting from the edge facing the respective heating structure, but it is also possible that the heating power density remains constant or possibly increases slightly over at least part of the width of the transition region.In this case, too, the heating power density decreases on average, with the averaging being an arithmetic spatial average over an arbitrary strip of the transition region whose width corresponds to 25% of the width of the transition region – which in this case is typically strip-shaped. The arithmetic mean of the heating power density in another strip adjacent to this one, which also corresponds to 25% of the width of the transition region and is located closer to the side of the transition region facing away from the heating structure, is lower than the arithmetic mean in the strip located closer to the side of the transition region facing the heating structure.

[0029] Minor deviations from a monotonically decreasing heating power density are acceptable due to the averaging effect of heat conduction. Even if no strip-shaped or defined transition zone exists, the heating power density of the edge structures decreases, at least on average, with increasing distance from a defined region of the heating structure, e.g., from a center point of the heating structure.

[0030] In a further embodiment, the transition area, a first further transition area in which the edge structures of the heating structure and edge structures of a third heating structure interlock, and a second

[0031] 2023P00638WO 14.10.2025 SZ00376PCT A further transition region, in which the edge structures of the further heating structure and the edge structures of the third heating structure interlock, abut each other at a vertex region. In the aspect of the invention described here, a comparatively large number of heating structures are typically used to cover the optical surface or the optically used area of ​​the surface of the optical component. With a typically regular tiling of the optical surface with the heating regions or the arrangement of the heating structures in a grid, at least three, and possibly more than three, transition regions abut each other at a vertex region. In the vertex region, the center lines of the transition regions typically intersect at a common point, which is also referred to as the vertex.It is possible that the edge structures of a given heating element do not interlock within the vertex region, for example, because they do not extend beyond the centerline of the respective transition zone. However, it is also possible that the edge structures within the vertex region form a vortex or interlocking spirals around the vertex to further mix or average the heating outputs of the three or more heating elements.

[0032] In another embodiment, the heating structures are designed as electrical conductors, whereby a spatially varying heating power density of the edge structures is generated by a spatially varying electrical resistance of the electrical conductors. In this embodiment, the heating structures are electrical resistance heating structures in the form of conductors. In this embodiment, the electrical resistance of the electrical conductors varies spatially, at least at the edge structures. In contrast, the core structure of the respective heating structure can have a substantially spatially constant electrical resistance, but the electrical resistance can also vary spatially, as described in the initial figure.

[0033] The application cited in DE102019202 531 A1, cited in 2023P00638WO 14.10.2025 SZ00376PCT, is incorporated in its entirety into this application by reference. The heating power density and the electrical resistance are typically inversely proportional, i.e., as the electrical resistance of the boundary structures or the trailing heating structures increases, the heating power density decreases. Various possibilities exist for the spatial variation of the electrical resistance.

[0034] In a further development of this embodiment, to generate the location-dependent varying electrical resistance, a cross-section of the electrical conductors, in particular a height and / or a width of the electrical conductors, at least a material property of the electrical conductors and / or a local area density of the electrical conductors varies depending on the location.

[0035] To achieve location-dependent variation of the electrical resistance and thus the location-dependent heating power density, the cross-section of the conductive traces can be varied. For this purpose, the width of the conductive traces can be varied in the plane in which they are applied to the material of the optical element. Alternatively or additionally, the height of the conductive traces perpendicular to the plane or position in which they are applied or run can be changed. For example, the conductive traces can be wedge-shaped for this purpose, with the wedge height typically increasing as the edge structure approaches the other heating structure. In this way, the cross-sectional area of ​​the structure is increased, and consequently—with the same material—the electrical resistance decreases, and with a constant applied current, the Joule heat dissipated decreases.

[0036] Alternatively, it is also possible to keep the cross-section of the conductor tracks constant or, if necessary, to change the cross-section of the conductor tracks only section by section.

[0037] 2023P00638WQ 14.10.2025 SZ00376PCT vary. In this case, too, the electrical resistance of the conductor tracks can be varied depending on the location if at least one material property of the electrical conductor tracks varies depending on the location. For example, the conductor track can be composed of a first material with a low specific electrical resistance and a second material with a high electrical resistance. If the electrical resistance is to be reduced locally, the proportion of the first material is increased locally. If the electrical resistance is to be increased locally, the proportion of the second material is increased locally. This can be achieved, for example, by forming a conductor track from parallel or overlapping strips of material whose width and / or height varies. Alternatively, the conductor track can be a composite material such as, for example,This could involve a simple mixture, an alloy, or a eutectic in which the material proportions, e.g., the stoichiometry of two metals in an alloy, are modified in a predetermined way. It is also possible to increase or decrease the doping of the material in the electrical conductor depending on the location, or to introduce holes into a specific electrical conductor.

[0038] Another way to achieve a spatially varying electrical resistance of the conductor tracks is to vary the local area density of the conductor tracks. The heating power density is proportional to the structure length of the conductor track in a given region of the heating structure or the edge structure. By varying the line length or the line density of the conductor track, a spatially dependent variation of the local heating power density or the local electrical resistance of the conductor tracks can also be achieved. Due to the averaging effect of heat conduction, smaller deviations from a monotonically or continuously changing electrical resistance, which serve to implement a near-manufacturable polynomial pattern, can be accepted.

[0039] 2023P00638WO 14.10.2025 SZ00376PCT In a further aspect of the invention, which is not usually combined with the first aspect, the at least one heating structure extends substantially over the entire optical surface of the optical component and has a locally varying electrical resistance, which preferably approximates a basis function extending over the entire optical surface, in particular a Zernike polynomial.

[0040] In contrast to the first aspect of the invention, in which a number of heating structures, generally more than, for example, five or ten, cover substantially the entire optical area of ​​the optical component, with each heating structure or its core structure not interfering with an adjacent heating structure, in the second aspect of the invention described here, the heating structure extends substantially over the entire optically used area of ​​the optical component. This does not mean that the heating structure covers the entire optical area; rather, gaps may also exist between substructures of the heating structure, provided that sufficient influence of the heating structure on these gaps can be ensured due to heat conduction.An extension "essentially" over the entire optical surface is understood to mean that in any contiguous sub-area of ​​the optical surface, the area of ​​which is 10% or more of the area of ​​the optical surface, a section or part of the heating structure is present.

[0041] In the first aspect of the invention, the heating structures are localized, i.e., limited to a typically small sub-area of ​​the optical surface, in order to adjust the temperature profile at the optical surface. This can potentially lead to high-frequency wavefronts and degrade image quality. In the aspect described here, at least one heating structure is used that approximates a global basis function, i.e., one extending over the entire optical surface. This can be achieved by a locally varying electrical resistance of the heating structure. Depending on

[0042] 2023P00638WO 14.10.2025 SZ00376PCT The heating power density of the heating structure does not necessarily vary across the entire structure according to the approximated basis function; that is, there can also be sections or sub-regions of the heating structure where the heating power density is constant. However, the heating power density of the heating structure varies at least section by section depending on location. The basis function could, for example, be a measure of a specific type of wavefront error that is to be compensated, such as astigmatism or distortion. The basis function describing such a wavefront error could, for example, be an orthogonal polynomial, in particular a Zernike polynomial.

[0043] In one embodiment, the optical component comprises at least one further heating structure having a locally varying heating power density and extending substantially over the entire optical surface of the optical component, wherein the heating structure and the further heating structure can be supplied with electric current independently of one another. The further heating structure preferably approximates a basis function extending substantially over the entire optical surface, in particular a Zernike polynomial.

[0044] In this embodiment, a number n of global basis functions are provided with the help of the heating structure and the at least one further heating structure to generate a heat input into the material of the optical component, from whose linear combination a desired temperature profile can be generated on the optically used surface.

[0045] In a further embodiment, the heating structure and preferably the further heating structure each have at least two substructures, each of which has a locally varying electrical resistance and which can preferably be supplied with current independently of one another, wherein in particular

[0046] 2023P00638WO 14.10.2025 SZ00376PCT at least one first section of a substructure of the heating structure is further apart from at least one first section of a substructure of the further heating structure than at least one second section of the substructure of the heating structure is from at least one second section of the substructure of the further heating structure.

[0047] In the embodiment described here, several substructures are used to realize a respective global basis function. These substructures can generally be supplied with electric current independently of one another. For example, the substructures can be parallel or substantially parallel conductor tracks or heating wires that exhibit a spatially varying electrical resistance, as described in more detail below. A basis function in the form of a Zernike polynomial, more precisely the amplitude of a Zernike polynomial, can be approximated, for example, by the spatially varying resistance of the heating structure or the substructures of the respective heating structure of a circular optical surface. Due to the spatially varying electrical resistance of the respective substructure, the same voltage can be applied to all substructures of the heating structure to generate the desired basis function, e.g., the amplitude of a Zernike polynomial.B. to generate a given Zernike polynomial.

[0048] In cases where two or more heating structures are arranged in the same position or plane and are to be controlled independently, e.g., to superimpose the heating power distribution of different Zernike polynomials, this can be achieved by appropriately grouping the substructures of the respective heating structures. For example, to implement ten Zernike polynomials, ten heating structures can be used, each with ten parallel conductor tracks on the optical surface, appropriately grouped, for example, by assigning conductor tracks 1, 11, 21, 31, ... the locally varying electrical resistance.

[0049] 2023P00638WO 14.10.2025 SZ00376PCT of the Zernike polynomial Z1, conductors 2, 12, 22, 32, ... carry the locally varying electrical resistance of the Zernike polynomial Z2, etc. Conductors 1 to 100 can, for example, run side by side at constant intervals on or along the optical surface. It is understood that the conductors do not necessarily have to be aligned parallel to each other, but can also have a different orientation in order to approximate a respective basis function.

[0050] In this case, the heating structure may only be functionally, but not physically, related, which is why several global basic functions can be implemented in an interlocking manner, as described above. For example, the second sections of the substructures, which are arranged at a smaller distance than the first sections, can overlap with each other. When controlling the heating structures, the often nonlinear response of the optical component's material to heating should be taken into account, so that different, simultaneously controlled basic profiles do not superimpose in a purely linear fashion, but rather exhibit greater deformation in an overlap region. This crosstalk can be accounted for computationally, for example, through simulations.If the basic functions are implemented using different, separately controllable substructures, these substructures can be controlled differently depending on whether one or more additional basic profiles are to be superimposed and, accordingly, whether one or more additional heating structures are to be activated simultaneously or not.

[0051] For the sake of simplicity, it is assumed below that a first basic function or a first heating structure is realized through the interaction of first sections of a respective substructure that can be separately supplied with electricity and similar second sections of the respective substructure. Likewise, a second basic function or a corresponding heating structure exhibits

[0052] 2023P00638WO 14.10.2025 SZ00376PCT two separately controllable sections of a respective substructure, distinct from the first. The first section(s) of a respective substructure of the first basic function and the first sections of the respective, typically adjacent, substructure of the second basic function are spatially clearly separated from each other. For example, an average distance or a minimum distance between the two first sections of the substructures can be 10 mm or 10% of the diameter of the optical surface or more. The second section of the respective substructure of the first basic function or the first heating structure and the second section of the respective substructure of the second basic function or the second heating structure, on the other hand, are closer together or overlap. If the first basic function is now controlled alone, e.g., with full deflection orWith full heating current, both the first and second sections of the substructure of the first basic function are addressed or controlled at 100%. However, if the second basic function is also to be superimposed, for simplicity also with full deflection, then the first sections of the substructure of the first basic function and the first sections of the substructure of the second basic function are each controlled at 100%, while the second sections of the substructure of the first basic function and the second sections of the substructure of the second basic function are each controlled at only 50%. Through their interaction in the overlap region, this results in power inputs that correspond to 100% of the first basic function and 100% of the second basic function.In this embodiment, the power input when controlling the second sections of the substructures is thus reduced relative to the first sections of the substructures when both heating structures are deflected together, compared to the deflection of only one of the two heating structures.

[0053] To approximate a global basic function, the heating structure can be designed as a continuous conductor instead of several independently electrically powered substructures. For the

[0054] 2023P00638WO 14.10.2025 SZ00376PCT For the approximation of multiple basis functions, a number n of conductor tracks can be used, each forming a heating structure and capable of being independently supplied with electric current. The conductor tracks or strands can follow a two-dimensional, space-filling, non-self-intersecting curve, such as a Peano curve, which completely traverses the optical surface or a regular grid describing the optical surface. The number of Peano curve iterations is chosen to be large enough when defining the respective curve to achieve the desired resolution (maximum spatial frequency). In this case, a number of strands or Peano curves is typically used that corresponds to the number n of basis functions. The strands typically run parallel to each other, offset from one another, within the unit cells of the optical surface grid.The electrical resistance in each unit cell of the Peano curve iteration can be adapted to the desired global basis function. This can be achieved by appropriately adjusting the electrical resistance of the respective strand within the unit cell, as described above in connection with the boundary structures.

[0055] If heating structures are used that each extend substantially over the entire optically effective area and are designed as a continuous conductor track, each heating structure can, for example, be designed as an elongated Peano curve extending to the edge or beyond the optically used area. The essentially parallel, elongated conductor track segments of this structure exhibit a spatially varying electrical resistance that can approximate the desired basis function, e.g., a specific Zernike polynomial. To approximate several Zernike polynomials in the same metallic layer, multiple laterally offset strands, each following the same Peano curve, can be used. In this case, it is generally advantageous if the variation in electrical resistance is achieved not by...

[0056] 2023P00638WO 14.10.2025 SZ00376PCT The width, but the height of the conductor tracks or another property of the conductor tracks varies depending on the location.

[0057] In a further embodiment, the heating structure is configured as an electrical conductor, or the at least two substructures of the heating structure are configured as at least two electrical conductors, wherein the locally varying electrical resistance of the heating structure is generated by a locally varying electrical resistance of the electrical conductor or the at least two electrical conductors. As described above, a heating structure approximating a global basis function can be implemented as a continuous conductor or as several substructures in the form of electrical conductors, each of which can be independently supplied with an electric current. The locally varying heating power density can be generated by a locally varying electrical resistance of the conductor or conductors.

[0058] As described above in connection with the boundary structures of the heating structures, to generate the locally varying electrical resistance, a cross-section of the electrical conductor or at least two electrical conductors, in particular a height and / or a width of the electrical conductor or at least two electrical conductors, at least one material property of the electrical conductor or at least two electrical conductors and / or a local area density of the electrical conductor or at least two electrical conductors can be varied depending on the location.

[0059] In particular, the location-dependent varying electrical resistance can be achieved by changing the line length and thus the line density of the electrical conductor(s), e.g. by implementing a zigzag-shaped conductor instead of a straight one.

[0060] 2023P00638WO 14.10.2025 SZ00376PCT is used to adapt the heat input in a unit cell to the respective basic function. In this case, the cross-sectional areas of the conductor track(s) can be location-independent; that is, the emitted heat power density is adjusted via the decreasing length of the heating structures towards a neighboring zone or unit cell.

[0061] In another embodiment, the electrical resistance of the conductor varies spatially along parallel sections of the conductor, or the electrical resistance varies spatially along at least two parallel conductors. A spatially dependent variation of the electrical resistance along parallel conductors or sections of conductors has proven advantageous. The spacing between the parallel conductors or sections of conductors is selected such that, due to heat conduction in the gap between the conductors, the heating element has a sufficient influence on the material of the optical component. In this way, a smooth transition in the temperature profile is created between adjacent conductors or sections of conductors.

[0062] In another embodiment, the at least one heating structure has at least one electrical conductor with a three-dimensional profile. The thermal transition between different heating zones or heating structures can also be optimized by a three-dimensional arrangement of electrical conductors. For this purpose, for example, a space-filling three-dimensional curve, e.g., the Hilbert curve (see, for example, "https: / / www.geogebra.org / rn / w8kchqzk" or "https: / / de.rn.wikipedia.org / wiki / Datei:Hilbert_curve_3D_Grundmuster.svg"), can be used as a starting point.

[0063] 2023P00638WO 14.10.2025 SZ00376PCT The curve of a basic curve is shifted apart in two planes, so that overlapping heating zones are formed, creating smooth transitions. The properties of the electrical conductors described above, which enable the generation of a locally varying electrical resistance, can also be applied to a three-dimensional curve of the electrical conductor or of several electrical conductors.

[0064] In a further development of this embodiment, the electrical conductor track with its three-dimensional orientation has a first section separated from a second section by an insulating layer, the electrical conductor track being plated through the insulating layer. In this case, the three-dimensional conductor track or the three-dimensional structure of the heating element is designed as an alternating layer structure, consisting of conductor layers carrying conductor tracks or heating elements and at least one insulating layer, arranged alternately. In such a structure, an insulating layer is located between each pair of conductor layers, with the conductor layers being plated through the insulating layer.

[0065] Another aspect of the invention relates to a semiconductor technology system, in particular an EUV lithography system, comprising: at least one optical component configured as described above, and a heating device for supplying the at least one heating structure with electric current. The EUV lithography system may be an EUV lithography system for exposing a wafer or another optical arrangement that uses EUV radiation, for example, an EUV inspection system, e.g., for inspecting masks, wafers, or the like used in EUV lithography.

[0066] The heating device can, for example, include a current or voltage source to power at least one heating structure.

[0067] 2023P00638WO 14.10.2025 SZ00376PCT to be subjected to electric current. If the heating structure, or a specific heating structure, is designed as a resistance heating structure, it is typically supplied with electric current or voltage via connections or leads. However, it is also possible for the heating structure to be supplied with electric current in another way using the heating device, for example, by inducing eddy currents in the heating structure, which in this case can, for example, form a planar, electrically conductive structure.

[0068] In one embodiment, the optical component is designed as a mirror operating at normal incidence and / or the optical component forms a first mirror downstream of an object field of the semiconductor technology system. A mirror operating at normal incidence is understood to be one in which the radiation strikes the surface at angles of incidence typically less than approximately 45°. Such a mirror typically has a multilayer coating with alternating layers of a material with a high and a low refractive index. At a useful wavelength of approximately 13.5 nm, the layer materials are typically silicon and molybdenum. The heating element can be positioned between the reflective multilayer coating and the substrate or the mirror material, as this prevents the reflectivity of the mirror from being affected by the heating element.The mirror in question can be, in particular, the first mirror after the object field of a semiconductor technology system, in this case an EUV lithography system, but this is not strictly necessary. Especially if the heating structure(s) are intended to generate a global basis function, e.g., a Zernike polynomial, it is advantageous for the mirror or the optical component to be located close to the pupil, i.e., in or near the pupil plane. In this way, the targeted basis function translates into a largely field-constant deformation.

[0069] 2023P00638WO 14.10.2025 SZ00376PCT Wavefront in the exit pupil. Even with mirrors located further away from the pupil plane, for example at a so-called "intermediate" position, the provision of the heating structure(s) described above can be advantageous. This is the case, for instance, with the first mirror after the object field in semiconductor technology systems, as it receives the highest power of all mirrors located after the object field due to the absorption of the incident radiation. Particularly at medium and higher apertures, the light beams from the object field diverge sufficiently quickly that even the first mirror has sufficient capability to compensate for aberrations on other mirrors closer to the pupil. This correction can lead to a significant reduction in the aberration contributions of these mirrors.

[0070] The optical component does not necessarily have to be a mirror; it can also be another type of optical element, such as a lens, a plane-parallel plate, etc. Furthermore, it is not essential that the heating structure is located between a reflective coating and the substrate of the mirror; it can be positioned elsewhere.

[0071] In a further embodiment, the semiconductor technology system comprises a resistance measuring device for measuring the electrical resistance of the at least one heating structure or of a substructure of the heating structure that can be independently supplied with electric current, and preferably a control or regulating device for controlling or regulating the heat input into the material of the optical component as a function of the measured electrical resistance of the at least one heating structure or of the substructure of the heating structure that can be independently supplied with current. In this embodiment, the electrical resistance of the heating structure or the substructure is measured on

[0072] 2023P00638WO 14.10.2025 SZ00376PCT measured in a suitable manner, e.g. using a bridge circuit. Due to the temperature dependence of the electrical resistance, this method enables temperature measurement at the location of this substructure or the heating structure.

[0073] The currently measured value of the electrical resistance can be taken into account by a control device when adjusting the applied current and / or voltage over time to ensure a desired constant or variable heat input. The heat input can be specifically targeted to establish a temperature field, the accuracy of which is increased by location-dependent temperature measurement based on the electrical resistance. It is also possible to use the resistance measurement not only to control the heating element or the independently current-controlled substructure(s), but also – possibly in combination – to control other manipulators present in the semiconductor technology system.Resistance measurement provides temperature information, which can improve the accuracy of knowledge about the overall state of the optical system and its aberrations, and thus provide an opportunity to optimize the use of further correction means, for example in the form of thermal manipulators.

[0074] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures in the drawing, which show details essential to the invention, and from the claims. The individual features can be implemented individually or in any combination in a variant of the invention.

[0075] drawing

[0076] 2023P00638WO 14.10.2025 SZ00376PCT Examples of implementation are shown in the schematic drawing and are explained in the following description. It shows

[0077] Fig. 1 schematically shows a projection exposure system for EUV projection lithography in meridional section.

[0078] Fig. 2 shows a schematic representation of an optical component in the form of a mirror with a plurality of hexagonal resistance heating structures arranged in a grid.

[0079] Fig. 3 shows a schematic representation of a transition area in which the edge structures of one heating structure and another heating structure interlock.

[0080] Fig. 4 shows a schematic representation of three transition regions adjacent to each other in a vertex region.

[0081] Fig. 5a shows a schematic representation of a heating structure which has a plurality of substructures in the form of electrical conductors with a spatially varying width to approximate a basis function in the form of the Zernike polynomial Z05,

[0082] Fig. 5b shows a schematic representation of a heating structure analogous to Fig. 5a, in which the conductor tracks with their location-dependent varying width approximate a basis function in the form of the Zernike polynomial Z10.

[0083] Fig. 6a, b schematic representations of a substructure of a heating structure and a substructure of another heating structure, which are in

[0084] 2023P00638WO 14.10.2025 SZ00376PCT exhibit sections arranged at different distances from each other,

[0085] Fig. 7a, b schematic representations of heating structures in the form of three conductor tracks following a Peano curve,

[0086] Fig. 8 shows a schematic representation of the three conductor tracks of Fig. 7a, b, where the line density is increased by changing the line length.

[0087] Fig. 9 shows a schematic representation of three heating structures in the form of modified Peano curves, which have elongated parallel sections,

[0088] Fig. 10a-c schematic representations of thickening profiles of the three heating structures of Fig. 9 for generating three basis functions in the form of the Zernike polynomials Z04, Z06 and Z07,

[0089] Fig. 11 shows a schematic representation of a basic curve of a three-dimensional Hilbert curve, as well as

[0090] Fig. 12 is a schematic representation of a heating structure with a three-dimensional conductor track based on the spread-out basic curve of Fig. 11.

[0091] In the following description of the drawings, identical reference symbols are used for identical or functionally equivalent components.

[0092] The following describes, with reference to Fig. 1, the essential components of an optical arrangement for EUV lithography in the form of a projection exposure system 1 for microlithography.

[0093] 2023P00638WO 14.10.2025 SZ00376PCT described. The description of the basic structure of the projection exposure system 1 and its components is not to be understood as restrictive.

[0094] One embodiment of a lighting system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, a lighting optic 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the lighting system. In this case, the lighting system does not include the light source 3.

[0095] A reticule 7 located in the object field 5 is illuminated. The reticule 7 is held by a reticule holder 8. The reticule holder 8 can be moved, particularly in one scanning direction, via a reticule displacement drive 9.

[0096] Figure 1 shows a Cartesian xyz coordinate system for illustrative purposes. The x-direction runs perpendicular to the plane of the drawing. The y-direction runs horizontally, and the z-direction runs vertically. In Figure 1, the scan direction runs along the y-direction. The z-direction runs perpendicular to the object plane 6.

[0097] The projection exposure system 1 comprises a projection system 10. The projection system 10 serves to image the object field 5 onto an image field 11 in an image plane 12. A structure on the reticulum 7 is imaged onto a light-sensitive layer of a wafer 13 located in the image plane 12 within the area of ​​the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, particularly along the y-direction, via a wafer transfer drive 15. The displacement of the reticulum 7 via the reticulum transfer drive 9 and of the wafer 13 via the wafer transfer drive 15 can be synchronized with each other.

[0098] 2023P00638WO 14.10.2025 SZ00376PCT Radiation source 3 is an EUV radiation source. Radiation source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation has a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be a plasma source, for example, an LPP source (Laser Produced Plasma, plasma generated using a laser) or a DPP source (Gas Discharged Produced Plasma, plasma generated by gas discharge). It can also be a synchrotron-based radiation source. Radiation source 3 can be a free-electron laser (FEL).

[0099] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector mirror 17. The collector mirror 17 can be a collector mirror with one or more ellipsoidal and / or hyperboloid reflective surfaces. The at least one reflective surface of the collector mirror 17 can be illuminated by the illumination radiation 16 at grazing incidence (Gl), i.e., with angles of incidence greater than 45°, or at normal incidence (NI), i.e., with angles of incidence less than 45°. The collector mirror 17 can be structured and / or coated to optimize its reflectivity for the useful radiation and to suppress stray light.

[0100] After the collector mirror 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector mirror 17, and the illumination optics 4.

[0101] 2023P00638WO 14.10.2025 SZ00376PCT The illumination optics 4 comprise a deflecting mirror 19 and, downstream in the beam path, a first faceted mirror 20. The deflecting mirror 19 can be a planar deflecting mirror or, alternatively, a mirror with an effect that influences the beam shape beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation 16 from stray light of a different wavelength. The first faceted mirror 20 comprises a plurality of individual first facets 21, which are hereinafter also referred to as field facets. Only a few of these facets 21 are shown in Fig. 1 as examples. In the beam path of the lighting optics 4, a second faceted mirror 22 is arranged downstream of the first faceted mirror 20. The second faceted mirror 22 comprises a plurality of second facets 23.

[0102] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (fly's eye integrator). With the aid of the second faceted mirror 22, the individual first facets 21 are imaged into the object field 5. The second faceted mirror 22 is the last beam-shaping, or indeed the last, mirror for the illumination radiation 16 in the beam path before the object field 5.

[0103] The projection system 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0104] In the example shown in Fig. 1, the projection system 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage for the illumination radiation 16. The projection system 10 is a

[0105] 2023P00638WO 14.10.2025 SZ00376PCT a double-obscured optic. The projection optic 10 has an image-side numerical aperture that is greater than 0.4 or 0.5 and that can also be greater than 0.6 and that can be, for example, 0.7 or 0.75.

[0106] The mirrors Mi, just like the mirrors of the lighting optics 4, can have a highly reflective coating for the lighting radiation 16.

[0107] Fig. 2 shows an optical component in the form of a mirror Mi, which is one of the mirrors Mi of the projection optics 10, for example, the first mirror M1 following the object field 5. The mirror Mi can serve as a thermal actuator and, for this purpose, has a plurality of approximately forty heating structures 25 in the example shown, which are designed as resistance heaters. The heating structures 25 have a hexagonal basic shape and are arranged in a grid with rows and columns. Each hexagonal heating structure 25 is formed by an electrical conductor which, following the hexagonal shape, fills the heating structure 25 in meandering patterns, as described in more detail, for example, in DE 102019202531 A1.

[0108] Each heating structure 25 is connected via connections (supply and return) not shown in Fig. 2 to a heating device 26, which is designed to supply the respective heating structure 25 with electric current or voltage. The heating structures 25 can each be supplied with electric current independently of one another in order to generate a desired temperature distribution on an optical surface 27 of a mirror surface 28 of the mirror Mi. The optical surface 27 represents the portion of the mirror surface 28 onto which the useful radiation in the form of EUV radiation 16 strikes. In the example shown, the majority of heating structures 25 cover only the optical surface 27, but can also be extended beyond the optical surface 27, for example, to thermally shield nearby heat sources or heat sinks.

[0109] 2023P00638WO 14.10.2025 SZ00376PCT In the mirror Mi shown in Fig. 2, the heating structures 25 are structured in only one electrical layer. Gaps are located between the hexagonal heating structures 25, in which the connections, or the supply and return lines for the electric current generated by the heating element 26, run. The electrical resistance of the connections, or the connecting lines, is typically chosen to be lower than the electrical resistance of the conductive traces of the heating structures 25, which is why the substrate material of the mirror Mi remains essentially unheated in the gaps, or spaces, between the heating structures 25. In Fig. 2, lower right, two connecting lines for the individual contacting of two heating structures 25 are shown; for illustrative purposes, they are depicted wider than they actually are.In the example shown, the material of the mirror Mi is a zero-expansion material in the form of titanium-doped quartz glass. The locally varying temperature of the mirror material Mi leads to a local deformation at the surface 28, and especially at the optical surface 27. This deformation can be adjusted using the heating device 26, thus enabling the correction of wavefront errors. A reflective multilayer coating is also applied to the surface 28 of the mirror Mi, shown in Fig. 2. This coating is located above the heating structures 25 and has been omitted for clarity. The multilayer coating has alternating layers of two materials with different refractive indices, which in this example are silicon and molybdenum.

[0110] For the correction of wavefront errors, a smooth, continuous temperature distribution across the optical surface 27 of the mirror Mi is typically advantageous. Due to the gaps between the heating structures 25, the heating device 26 generates a temperature distribution on the optical surface 27 that exhibits abrupt transitions between adjacent heating structures 25, which is optically undesirable because it disrupts the set actual temperature.

[0111] 2023P00638WO 14.10.2025 SZ00376PCT Temperature distribution on the optical surface 27 systematically deviates from a target temperature distribution on the optical surface 27.

[0112] Fig. 3 shows a detailed view of a heating structure 25a and an adjacent heating structure 25b, each comprising a core structure 29a, 29b and a boundary structure 30a, 30b. As in the heating structures 25 shown in Fig. 2, the core structures 29a, 29b are hexagonal, and their hexagonal shape is filled by a meandering conductive trace. Between the two core structures 29a, 29b, as in the heating structures 25 of Fig. 2, there is a gap in the form of a strip-shaped transition region 31, in which the boundary structures 30a of heating structure 25a and the boundary structures 30b of the adjacent heating structure 25b interlock. The boundary structures 30a, 30b are electrically connected to the respective core structures 29a, 29b, or rather, these form a continuous conductive trace.

[0113] The edge structures 30a of the heating structure 25a have a first side 32a facing away from the further heating structure 25b and located at an edge 34a of the transition region 31 facing the heating structure 25a, which corresponds to the edge of the core structure 29a of the heating structure 25a. The edge structures 30a of the heating structure 25a also have a second side 32b facing the further heating structure 25b. Starting from the first edge 34a of the strip-shaped transition region 31 facing the heating structure 25a, the edge structures 30a of the heating structure 25a have an average increasing cross-section or an average increasing width b, such that the edge structures 30a emit less heating power the closer the edge structures 30a come to the adjacent heating structure 25b.The heating power density la of the edge structures 30a of the heating structure 25a is therefore lower on its second side 32b, facing the further heating structure 25b, than on its first side 32a, facing the heating structure 25a. This is due to the cross-section of the edge structures 30a of the first, which increases on average with increasing distance from the first edge 34a of the transition region 31.

[0114] 2023P00638WQ 14.10.2025 SZ00376PCT Heating structure 25a the electrical resistance Ra of the edge structures 30a decreases on average with increasing distance from the first edge 34a of the transition region 31.

[0115] The same applies to the boundary structures 30b of the further heating structure 25b, which interlock with the boundary structures 30a of the heating structure 25a in the transition region 31. The boundary structures 30b of the further heating structure 25b have a first side 33a facing away from the heating structure 25a and which runs along a second edge 34b of the transition region 31, corresponding to the edge of the core structure 29b of the further heating structure 25b. The heating power density Ib of the boundary structures 30b of the further heating structure 25b is greater on the first side 33a than on the second side 33b of the boundary structures 30b of the further heating structure 25b. Accordingly, the electrical resistance Rb of the boundary structures 30b of the further heating structure 25b is smaller on the second side 33b than on the first side 33a.

[0116] In the manner described above, the contribution of the heating power density la of the boundary structures 30a of the heating structure 25a in the transition region 31 decreases with increasing distance from the core zone 29a of the heating structure 25a; that is, on average, they emit less power the closer they get to the further heating structure 25b. The same applies to the heating power density Ib of the boundary structures 30b of the further heating structure 25b. This allows a smooth transition of the heating power profile and thus of the temperature profile between the two heating structures 25a, 25b.

[0117] The width B of the transition area 31 in the Y direction, i.e., perpendicular to the two edges 34a, 34b, is on the order of approximately 500 pm, meaning the transition area 31 is comparatively narrow. Due to the interlocking of the edge structures 30a, 30b of the heating structures 25a, 25b, it is possible to connect the heating structures 25a, 25b between the edge structures 30a,

[0118] 2023P00638WO 14.10.2025 SZ00376PCT 30b to enable the heating structures 25a, 25b to be controlled by the heating device 26. Instead of a toothed connection, another type of interlocking is also possible, for example, a nesting of the edge structures 30a, 30b. The connecting lines described above run in the transition area 31 between the edge structures 30a, 30b of the heating structures 25a, 25b and are not shown in Fig. 3 for the sake of simplicity.

[0119] In the tiling of the optical surface 27 with the hexagonal heating structures 25 shown in Fig. 2, a transition region 31 runs between adjacent edges of each pair of heating structures 25. At the corners of the hexagonal heating structures 25, three transition regions 31, 31', 31" each adjoin a common vertex region 35 in the form of an equilateral triangle, as shown in Fig. 4. As in Fig. 2, in the example of Fig. 4, the respective edge structures 30a, 30b interlock in the transition region 31 between the two heating structures 25a, 25b. In the second transition region 31', the edge structures 30a of the first heating structure 25a and edge structures 30c of a third heating structure 25c interlock. In the third transition region 31", the edge structures 30b of the second heating structure 25b and the edge structures 30c of the third heating structure interlock. 30c into each other.

[0120] In the vertex region 35, the boundary structures 30a-c of the three heating structures 25a-c do not interlock in the example shown, as they do not extend beyond the respective center lines of the transition regions 31, 31', 31". However, interlocking of the boundary structures 30a-c is fundamentally possible in the vertex region 35; for example, the boundary structures 30a-c could be nested in the manner of a vortex, interlocking spirals, or the like.

[0121] 2023P00638WO 14.10.2025 SZ00376PCT In the example shown in Fig. 4, the boundary structures 30a-c of the three heating structures 25a-c have a constant cross-section, unlike the boundary structures 30a, b in Fig. 3. In this case, the heat output or the heat power density is proportional to the structure length. In the example shown, the sum of the boundary structures 30a of the heating structure 25a adjacent to the core structure 29a is greater than at a greater distance from the core structure 29a; that is, the area density of the boundary structures 30a of the heating structure 25a decreases on average with increasing distance from the core structure 29a. In Fig. 4, the ratio of the area density 36 of the boundary structures 30a of the heating structure 25a and the boundary structures 30b of the other heating structure 25b in the transition region 31 is shown on the left. The one in Fig.The 4 depicted boundary structures 30a-c of the three heating structures 25a-c each represent a section of a continuous conductor track, which also fills the core area 29a-c of a respective heating structure 25a-c in the manner of a meander.

[0122] Alternatively or additionally to varying the electrical resistance Ra, Rb, ... of the boundary structures 30a-c by varying the width b or the local areal density 36, the cross-section can also be varied by varying the height of the conductor tracks forming the boundary structures 30a-c, i.e., a variation in a direction perpendicular to the XY plane shown in Fig. 3. The boundary structures 30a-c can, for example, form a wedge structure, with the wedge height increasing on average over the transition region 31 in the direction of the respective adjacent heating structure 30a-c. Alternatively or additionally, at least one material property of the electrical conductor tracks forming the boundary structures 30a-c can also vary depending on location; for example, a material composition can vary if the electrical conductor tracks forming the heating structures 30a-c are composed of two materials with different specific electrical resistances.

[0123] 2023P00638WQ 14.10.2025 SZ00376PCT In Figures 2 to 4, a plurality of heating structures 25a-c, each of which can be independently energized and which cover different sub-areas of the optical surface 27, are used to establish a fundamentally arbitrary, location-dependent temperature distribution on the optical surface 27. Figures 5a and 5b each show a heating structure 25, 25' which differs from the heating structures 25 and 25a-c shown in Figures 2 to 4 in that the respective heating structure 25, 25' serves to approximate a fixed, global basis function by means of a location-dependent varying electrical resistance distribution Ra(x, y) and Rb(x, y) over the entire optical surface 27. For this reason, the respective heating structure 25, 25' extends essentially over the entire optical surface 27.

[0124] The locally varying electrical resistance distribution Ra(x, y) or Rb(x, y) is generated in Fig. 5a and Fig. 5b, respectively, by the fact that the respective heating structure 25 has a number n of parallel, straight substructures in the form of electrical conductors 37.1 to 37.n, 37.1' to 37.n' or in the form of heating wires, whose electrical resistance Ra.1 to Ra.n, Rb.1 to Rb.n or whose resistance profile varies along the respective conductor 37.1 to 37.n, 37.T to 37.n' depending on the location.

[0125] In the example shown in Fig. 5a, the spatially dependent variation of the electrical resistance of all conductor tracks 37.1 to 37.n is chosen such that a spatially varying electrical resistance distribution Ra(x, y) is generated over the entire optically used area 27, or over the surface of the mirror Mi, which is simplified to a circular area. When current is applied, this distribution approximates a basis function in the form of the Zernike polynomial Z05. Similarly, in the example shown in Fig. 5b, the spatially varying electrical resistance distribution Rb(x, y) of the conductor tracks 37.T to 37.n' is chosen such that the Zernike polynomial Z10 is approximated at the optically used area 27.

[0126] 2023P00638WO 14.10.2025 SZ00376PCT In the example shown in Fig. 5a and Fig. 5b, the conductor tracks 37.1 to 37.n and 37.1' to 37.n' can, in principle, be energized independently of one another. However, it is also possible that the conductor tracks 37.1 to 37.n and 37.1' to 37.n' cannot be energized independently of one another. For example, the conductor tracks 37.1 to 37.n, 37.1' to 37.n', or some of the conductor tracks 37.1 to 37.n and 37.1' to 37.n' can be connected in parallel and supplied with an identical voltage by means of the heating device 26 shown in Fig. 2. In this case, the variable current through the respective conductor tracks 37.1 to 37.n, 37.1' to 37.n' can also contribute to the desired resistance distribution Ra(x,y), Rb(x,y) if it is appropriately considered during the design. The parallel connection allows for a reduction in the number of supply and return leads. Therefore, it may be necessary to...It is useful that some of the conductor tracks 37.1 to 37. n, 37.1' to 37. n' can be individually and independently supplied with current, while other conductor tracks 37.1 to 37. n, 37.1 ' to 37. n' are connected in parallel and supplied with an identical voltage.

[0127] In the example shown in Fig. 5a and Fig. 5b, the electrical resistance Ra.1 to Ra.n, Rb.1' to Rb.n' is varied depending on location by changing the cross-section, more precisely the width b, of a respective electrical conductor 37.1 to 37.n, 37.1' to 37.n' depending on the location along the respective conductor 37.1 to 37.n or 37.1' to 37.n', which extend in the Y direction of an XY coordinate system in Fig. 5a and Fig. 5b. Instead of the width b of the respective electrical conductor tracks 37.1 to 37.n, 37.1' to 37.n', their height can also vary depending on the location in order to realize a locally varying electrical resistance Ra.1 to Ra.n, Rb.1' to Rb.n', or a property of the material of the conductor tracks 37.1 to 37.n, 37.1' to 37.n' can be suitably varied.

[0128] 2023P00638WO 14.10.2025 SZ00376PCT It is understood that alternatively, other Zernike polynomials can also be approximated at the optical surface 27 by a suitably locally varying electrical resistance of the electrical conductors 37.1 to 37.n. For the compensation of wavefront errors, it can be advantageous if two or more Zernike polynomials at the optical surface 27 can be approximated by two or more heating structures 25, 25', ... with suitably locally varying electrical resistances Ra(x,y), Rb(x,y), ... such that a temperature profile is generated at the optical surface 27 that forms a superposition or a linear combination of two or more Zernike polynomials. For this purpose, for example, the electrical conductors 37.1' to 37.n' of the heating structure 25' of Fig. 5b can be arranged or suitably grouped in the gaps between the electrical conductors 37.1 to 37.n of the heating structure 25 of Fig. 5a.In the representation of Fig. 5a and Fig. 5b, electrical conductors 37.1 to 37.n of the heating structure 25 of Fig. 5a alternate from left to right in this case, and electrical conductors 37.1' to 37.n' of the heating structure 25' of Fig. 5b alternate.

[0129] Fig. 6a shows a substructure 37.1 of a first heating structure 25 (see Fig. 5a), in which the electrical resistance Ra.1 is varied by the substructure 37.1 having three sections A1, A2, A3 with different electrical resistances. In the first and third sections A1, A3, the substructure 37.1, or rather the respective electrical conductor, has the same geometry and the same area density, while in the second section A2 the area density is lower. Also shown in Fig. 6a is a substructure 37.1' of a second heating structure 25' (see Fig. 5b), in which the electrical resistance Rb.1 is likewise varied by the substructure 37.1' having three sections AT, A2', A3' with conductors of different area densities.

[0130] 2023P00638WO 14.10.2025 SZ00376PCT As can also be seen in Fig. 6a, the first and third sections A1, A3 of substructure 37.1 of the first heating structure 25 are further apart from the longitudinally corresponding first section AT, A3' of substructure 37.1' of the second heating structure 25' than the second section A2 of substructure 37.1 of the first heating structure 25 is from the second section A2' of substructure 37.T of the second heating structure 25'. The two substructures 37.1, 37.T overlap in their respective second sections A2, A2'.

[0131] Fig. 6b shows a representation analogous to Fig. 6a, in which the three sections A1, A2, A3 of substructure 37.1 of the first heating structure 25 can be energized independently of one another, i.e., they do not form a common conductor track. Similarly, the three sections AT, A2', A3' of substructure 37.T of the second heating structure 25' can also be energized independently of one another. The first and third sections A1, A3 of substructure 37.1 of the first basis function or the first heating structure 25 and the first and third sections AT, A3' of the adjacent substructure 37.T of the second basis function or the second heating structure 25' are spatially clearly separated from one another.

[0132] The second section A2 of substructure 37.1 of the first heating structure 25 and the second section A2' of substructure 37.1 ' of the second heating structure 25', however, are closer together and overlap.

[0133] If the first basic function or the first heating structure 25 is controlled alone, e.g., with full deflection or full heating current, then all three sections A1, A2, A3 of substructure 37.1 of the first heating structure 25 are addressed or controlled at 100% each. However, if the second basic function or the second heating structure 25' is to be superimposed simultaneously, also with full deflection for simplification, then the first and third sections A1, A3 of substructure 37.1 of the first heating structure 25 and the first and third sections AT, A3' of substructure 37.T of the second heating structure 25' are each controlled at 100%, while the second section A2 of substructure 37.1 of the

[0134] 2023P00638WO 14.10.2025 SZ00376PCT first heating structure 25 and the second section A2' of substructure 37.1' of the second heating structure 25', however, only to 50% each.

[0135] The interaction in the overlap region results in power inputs that correspond to 100% of the first basic function and 100% of the second basic function. In the example shown in Fig. 6b, the power input when controlling the second sections A2, A2' of substructures 37.1, 37.T is thus reduced relative to the first and third sections A1, A3 of substructure 37.1 of the first heating structure 25 or the first and third sections AT, A3' of substructure 37.T of the second heating structure 25' when both heating structures 25, 25' are deflected together, compared to deflecting only one of the two heating structures 25 or 25'.

[0136] Similarly, three or more heating structures 25, 25', ... can be formed on the optical surface 27 to approximate three or more Zernike polynomials, which serve as basis functions and can be independently supplied with current to generate a desired temperature distribution on the optical surface 27. The fact that the Zernike functions form an orthogonal basis on the circular optical surface 27 is advantageous for correcting the wavefront error.

[0137] The heating device 26 shown in Fig. 2 includes, in the example shown, a measuring device 26a for measuring the electrical resistance Ra.1 to Ra.n of each independently current-energized substructure 37.1 to 37.n in the form of a respective electrical conductor 37.1 to 37.n. In the example shown, the measuring device 26a is designed as a Wheatstone bridge circuit. Due to the temperature dependence of the electrical resistance Ra.1 to Ra.n, a temperature measurement at the location of the respective substructure 37.1 to 37.n is possible. The currently measured value of the electrical resistance Ra.1 to Ra.n is controlled by a control or

[0138] 2023P00638WO 14.10.2025 SZ00376PCT The control device of the heating unit 26 is taken into account during the time-dependent adjustment of the supplied current and / or the applied voltage in order to ensure a desired constant or variable heat input profile into the material of the optical component Mi. It is understood that a resistance measurement and control or regulation of the current and / or voltage can also be carried out in a corresponding manner for the heating structures 25 shown in Fig. 2.

[0139] While in Fig. 5a and in Fig. 5b or Fig. 6a, b a plurality of parallel or substantially parallel electrical conductors 37.1 to 37.n, 37.1' to 37.n' are used to form a heating structure 25, 25' extending over the entire optical surface 27, it is also possible to realize a heating structure 25 with a desired spatially varying electrical resistance in the form of a single continuous conductor 37, 38, 39. For this purpose, a space- or area-filling curve can advantageously be used or suitably modified, as described below in connection with Fig. 7a, b using a Peano curve. Fig. 7a shows a first iteration of the Peano curve, more precisely three parallel offset strands in the form of parallel offset conductors 37, 38, 39, each following a Peano curve. Fig. 7b shows a second iteration of the Peano curve from Fig.7a, where, for simplification, only the first of the three Peano curves or the first conductor track 37 is shown in most of the area covered by the Peano curves 37, 38, 39. The iteration shown in Fig. 7a, b can be continued until the desired spatial resolution or maximum spatial frequency is reached.

[0140] The spatially varying electrical resistance of the electrical conductors 37, 38, 39 can be adjusted in a respective unit cell by a suitable adaptation of the cross-section, as described in connection with Fig. 3, or by a variation of the

[0141] 2023P00638WO 14.10.2025 SZ00376PCT Area density or length of the respective conductor tracks 37, 38, 39 in the respective unit cell. Fig. 8 shows, by way of example, the increase in line density when transitioning from a straight course of the conductor tracks 37, 38, 39 to a zigzag course of the conductor tracks 37, 38, 39.

[0142] A modified Peano curve configuration of the conductor tracks 37, 38, 39, which has proven particularly advantageous for the fabrication of the heating structure 25 described here, is shown in Fig. 9. In this case, the conductor tracks 37, 38, 39 have a plurality of parallel, elongated sections extending in the Y direction of an XY coordinate system. The respective conductor track 37, 38, 39 can extend over the entire optical surface 27 of the mirror Mi in the manner shown in Fig. 9, as illustrated in Figs. 10a-c, where, as in Figs. 5a and 5b, the optical surface 27 has been assumed to be circular for simplification.

[0143] As shown in Figs. 5a and 5b, the electrical resistance Ra(x,y), Rb(x,y), Rc(x,y) of the heating structure 25, 25', 25", generated in Figs. 10a-c by the respective conductor track 37, 38, 39 varies spatially across the optical surface 27. More precisely, the parallel elongated sections 37.1 to 37.n, 38.1 to 38.n, 39.1 to 39.n of the respective conductor track 37, 38, 39 exhibit a spatially varying electrical resistance in the Y-direction Ra.1 to Ra.n, Rb.1 to Rb.n, Rc.1 to Rc.n, which is selected such that the electrical resistance Ra(x,y), Rb(x,y), Rc(x,y) of the respective heating structure 25, 25', 25” approximates the Zernike polynomial Z04, Z05 or Z07.

[0144] Two or more of the heating structures 25, 25', 25” can extend across the optical surface 27 if the respective conductor tracks 37, 38, 39 are nested within each other as shown in Fig. 9 or run as several parallel, offset strands. In this case, to avoid overlaps between adjacent sections 37.1 to 37.n, 38.1 to 38.n, 39.1 to 39.n of the

[0145] 2023P00638WO 14.10.2025 SZ00376PCT To avoid variations in the electrical resistance Ra.1 to Ra.n, Rb.1 to Rb.n, Rc.1 to Rc.n of sections 37.1 to 37.n, 38.1 to 38.n, 39.1 to 39.n, the height or another property of the conductors 37, 38, 39 can vary depending on the location instead of the width b.

[0146] In the examples described above, it was assumed that the heating structures 25, 25', 25", ... run in a common plane or in a common conductor layer. However, it is also possible to realize a three-dimensional heating structure 25. For this purpose, instead of a two-dimensional space-filling curve, as shown in Fig. 7a, b, a three-dimensional space-filling curve in the form of a Hilbert curve can be used. Fig. 11 shows an electrical conductor 37 with a three-dimensional path that follows a basic curve of a unit cell of a three-dimensional Hilbert curve.

[0147] Fig. 12 shows the conductor track 37 from Fig. 11 with a slightly modified path, in which the basic curve has been spread apart by shifting a first, lower section 37a of the conductor track 37 to the right and a second, upper section 37b of the conductor track 37 to the left, as indicated by two arrows in Fig. 12. The first section 37a and the second section 37b of the conductor track 37 each run in a conductor layer (not shown) and are separated from each other by an insulating layer 40, which in the example shown is made of Al₂O₃, but could also be made of another material. A connecting section 37c of the conductor track 37 connects the lower section 37a to the upper section 37b of the conductor track 37, with the connecting section 37c of the conductor track 37 being plated through the insulating layer 40.

[0148] 2023P00638WO 14.10.2025 SZ00376PCT Due to the lateral offset of the lower section 37a and the upper section 37b of the conductor track 37 relative to each other, a smooth transition of the temperature profile between two adjacent heating zones 41a, 41b can also be generated in a transition area 31 using the heating structure 25 shown in Fig. 12. The heating structure 25 shown in Fig. 12 can, in principle, be a layered structure in which insulating layers and conductive layers, i.e., layers carrying one or more conductor tracks, alternate. Typically, an insulating layer is located between two conductive layers, with the conductive layers being plated through-hole.

[0149] 2023P00638WO 10 / 14 / 2025 SZ00376PCT

Claims

Patent claims 1. Optical component, in particular mirror (Mi), comprising: at least one heating structure (25, 25a) that can be acted upon with an electric current, in particular a resistance heating structure, for introducing heat into a material of the optical component, characterized in that the at least one heating structure (25) extends substantially over the entire optical surface (27) of the optical component and has a locally varying electrical resistance (Ra(x,y)) which preferably approximates a basis function extending substantially over the entire optical surface (27), in particular a Zernike polynomial, wherein the heating structure (25) is designed as an electrical conductor (37) or at least two substructures of the heating structure (25) are designed as at least two electrical conductors (37.1 to 37.2).n) are formed, wherein the locally varying electrical resistance (Ra(x,y)) of the heating structure (25) is generated by a locally varying electrical resistance (Ra.1 to Ra.n) of the electrical conductor (37) or of the at least two electrical conductors (37.1 to 37.n), and, in which the electrical resistance (Ra.1 to Ra.n) of the electrical conductor (37) varies spatially along parallel sections (37.1 to 37.n) of the conductor (37), or in which the electrical resistance (Ra.1 to Ra.n) varies spatially along the at least two parallel electrical conductors (37.1 to 37.n).

2. Optical component according to claim 1, further comprising: at least one further heating structure (25', 25”), which extends substantially over the entire optical surface (27) of the optical component and has a locally varying electrical resistance (Rb(x,y), Rc(x,y)), wherein the heating structure (25) and the further heating structure (25', 25”) can be supplied with electric current independently of each other. 2023P00638WO 10 / 14 / 2025 SZ00376PCT 3. Optical component according to claim 1 or 2, wherein the heating structure (25) and preferably the further heating structure (25') each have at least two substructures (37.1 to 37.n; 37.T to 37.n') having a locally varying electrical resistance (Ra.1 to Ra.n; Rb.1 to Rb.n) and which are preferably independently energizable, wherein in particular at least a first section (A1, ... ) of a substructure (37.1, ... ) of the heating structure (25) is further spaced from at least a first section (AT, ... ) of a substructure (37.T, ... ) of the further heating structure (25') than at least a second section (A2) of the substructure (37.1, ... ) of the heating structure (25) is spaced from a second section (A2') of the substructure (37., ... ) of the further heating structure (25').

4. Optical component according to one of the preceding claims, wherein the at least one heating structure (25) has at least one electrical conductor (37) with a three-dimensional orientation.

5. Optical component according to claim 4, wherein the electrical conductor (37) with the three-dimensional orientation has a first section (37a) which is separated from a second section (37b) by an insulating layer (40), wherein the electrical conductor (37) is plated through the insulating layer (40).

6. Optical component according to one of the preceding claims, wherein the heating structure (25a) and a further, adjacent heating structure (25b) have interlocking edge structures (30a, 30b), wherein a heating power density (1a) of the edge structures (30a) of the heating structure (25a) on a side (32b) of the edge structures (30a) of the heating structure (25a) facing the further heating structure (25b) is smaller than on a side (32a) facing away from the further heating structure (25b). 2023P00638WO 10 / 14 / 2025 SZ00376PCT boundary structures (30a) of the heating structure (25a), and / or wherein a heating power density (Ib) of the boundary structures (30b) of the further heating structure (25b) on a side (33b) facing the heating structure (25a) of the boundary structures (30b) of the further heating structure (25b) is smaller than on a side (33a) facing away from the heating structure (25a) of the boundary structures (30b) of the further heating structure (25b).

7. Optical component according to claim 6, in which the edge structures (30a) of the heating structure (25a) and the edge structures (30b) of the further heating structure (25b) interlock in a preferably strip-shaped transition area (31) of the two heating structures (25a, 25b).

8. Optical component according to claim 7, in which the heating power density (1a) of the edge structures (30a) of the heating structure (25a) decreases at least on average from an edge (34a) of the transition region (31) facing the heating structure (25a) and / or in which the heating power density (1b) of the edge structures (30b) of the further heating structure (25b) decreases at least on average from an edge (34b) of the transition region (31) facing the further heating structure (25b).

9. Optical component according to claim 7 or 8, wherein the transition region (31), a first further transition region (31') in which the edge structures (30a) of the heating structure (25a) and edge structures (30c) of a third heating structure (25c) interlock, and a second further transition region (31”) in which the edge structures (30b) of the further heating structure (25b) and the edge structures (30c) of the third heating structure (25c) interlock, are adjacent to each other at a vertex region (35). 2023P00638WO 10 / 14 / 2025 SZ00376PCT 10. Optical component according to one of the preceding claims, in which, to generate the spatially varying electrical resistance (Ra, Rb, ... ), a cross-section of the electrical conductors (25a-c), in particular a height and / or a width (b) of the electrical conductors (25a-c), at least one material property of the electrical conductors (25a-c) and / or a local area density (36) of the electrical conductors (25a-c) varies spatially.

11. Semiconductor technology system, in particular EUV lithography system (1) comprising: at least one optical component according to one of the preceding claims, and a heating device (26) for supplying the at least one heating structure (25, 25a) with electric current.

12. Semiconductor technology system according to claim 11, wherein the optical component is designed as a mirror (Mi) which is operated in normal incidence and / or wherein the optical component forms a first mirror (Mi) after an object field (5) of the semiconductor technology system (1 ).

13. Semiconductor lithography system according to claim 11 or 12, further comprising: a resistance measuring device (26a) for measuring an electrical resistance (Ra.1 to Ra.n) of the at least one heating structure (25, 25a) or of an independently current-energized substructure (37.1 to 37.n) of the heating structure (25), wherein the heating device (26) is preferably used for controlling or regulating the heat input into the material of the optical component (Mi) as a function of the measured electrical resistance (Ra.1 to Ra.n) of the at least one heating structure (25, 25a) 2023P00638WO 10 / 14 / 2025 SZ00376PCT or is formed as the independently electrically supplied substructure (37.1 to 37.n) of the heating structure (25). 2023P00638WO 10 / 14 / 2025 SZ00376PCT

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