Method for producing an optical component, optical component and semiconductor technology apparatus

Abstract

The invention relates to a method for producing an optical component, preferably a mirror, in particular an EUV mirror (Mi), comprising: providing at least two partial bodies (25, 26), preferably made of a glass material, and connecting the at least two partial bodies (25, 26) to form the optical component while providing at least one joining face (29), preferably by high-temperature bonding. In the method, the optical component is formed, in particular curved, during the high-temperature bonding. The invention also relates to an optical component, preferably a mirror (Mi), produced by the method and to a semiconductor technology apparatus comprising at least one such optical component.

Description

[0001] Stuttgart, 11.09.2025 SZ00393PCT Rp / pt

[0002] Method for producing an optical component, optical component and semiconductor technology apparatus

[0003] Cross-Reference to related application

[0004] This application claims priority to German Patent Application No.

[0005] 102024208945.1 , filed September 18, 2024, the entire disclosure of which is considered part of and is incorporated by reference in the disclosure of this application.

[0006] Background of the invention

[0007] The invention relates to a method for producing an optical component, preferably a mirror, in particular an EUV mirror, comprising: providing at least two partial bodies, preferably made of at least one glass material, and connecting the at least two partial bodies to form the optical component while providing at least one joining face, preferably by high-temperature bonding. The invention also relates to an optical component produced by the method and to a semiconductor technology apparatus comprising such an optical component.

[0008] Optical components, in particular in the form of mirrors of a projection system, which are located in a semiconductor technology apparatus in the form of an EUV lithography apparatus, are exposed during operation to high radiant power that leads to a warming of the mirror, more specifically the mirror substrate which together with a reflective coating forms the mirror. The reflective coating is applied to an optically effective surface of the mirror substrate. The warming of the mirror substrate leads to deformations of the optically effective surface and can adversely affect the imaging quality of the projection system. In order to counter this problem, use is typically made of substrates made of glass

[0009] 2024P00012WO 11.09.25 SZ00393PCT materials which have a low coefficient of thermal expansion, for example titanium-doped fused silica.

[0010] The two partial bodies can consist of the same glass material or of two or more different glass materials. "The same glass material" is understood to mean that the glass material of the two partial bodies has practically the same properties, for example because the two partial bodies were cut from the same glass blank. Different glass materials are present e.g. when the glass materials of the two partial bodies have functionally different properties, or the two partial bodies consist of different types of glass.

[0011] To reduce the temperature of the mirrors it is known practice to provide the mirror substrate with cooling channels through which a cooling fluid flows. The production of the cooling channels requires passage channels, which have a geometry that depends on the respective mirror, to be formed in the substrate. When the substrate is being processed to produce the cooling channels, stresses that can lead to undesired changes in shape can arise in the glass material. Mechanical loading caused for example by the holder or mount of the optical component, by actuation of the latter during operation, or by attachments fastened to the substrate can, depending on the direction of the mechanical loading, lead to material stresses which have an effect on the optically effective surface or an optically effective portion of the optically effective surface.

[0012] When the mirror is being produced, moreover the smallest possible producible structures and gradients on the optically effective surface are limited, among other things, by the tool size of the sub-aperture processes. On the optically effective surface, it is therefore generally not possible to form any local structures, e.g. in the form of local elevations or the like, which have a smaller extent than the sub-aperture.

[0013] 2024P00012WO 11.09.25 SZ00393PCT In the case of high-temperature bonding, also referred to as direct bonding, two or more partial bodies generally consisting substantially of the same glass material or of different glass materials are heated typically to a temperature above the glass transition temperature of the glass material. The glass transition temperature depends on the material and is typically approximately 1000°C or higher. On exceeding the glass transition temperature, the glass transitions into a viscous state. This allows the respective surfaces of the partial bodies to be fused, with the formation of covalent bonds which lead to two adjacent partial bodies being permanently connected to one another on a respective joining face without the use of a joining agent. On exceeding the glass transition temperature, moreover the history of the glass material is "erased". The "erasure" relates for example to properties of the glass material such as the zero crossing temperature and the mechanical stresses introduced. The melting temperature of the glass material should be distinguished from the glass transition temperature; it is higher than the glass transition temperature and can lie for example between approximately 1300°C and 1500°C. Partial bodies which do not consist of a glass material, for example in the form of semiconductor materials, e.g. in the form of silicon, can also be connected to one another so as to provide at least one joining face. The joined-together partial bodies can consist of the same material, but the joined-together partial bodies can also consist of different materials.

[0014] The joining face formed when two partial bodies are connected to one another to form an optical component in the form of a mirror can be plane or have a curvature. The latter allows cooling channels that have a constant spacing from the likewise curved optical surface of the mirror to be provided in the mirror in the region of the joining face, as described for example in WO2022 / 214290A1. In particular, the contact or joining face can for this purpose have a curvature which substantially matches the curvature of the optically effective surface of the mirror.

[0015] 2024P00012WO 11.09.25 SZ00393PCT W02020 / 207741 A1 describes a method for producing a glass body which has at least one cooling channel, comprising: providing a first partial body and a second partial body, and producing the glass body by connecting the first partial body to the second partial body by high-temperature bonding, while embedding at least one placeholder made of a temperature-resistant material between the two partial bodies. The placeholder may be tubular and, after the glass body is produced, remain in the cooling channel. As an alternative, after the glass body is produced the placeholder can be removed from the glass body, in order to form the cooling channel.

[0016] Object of the invention

[0017] An object of the invention is to provide a method for producing an optical component, an optical component and a semiconductor technology apparatus, in the case of each of which the optical component is modified when the partial bodies are being connected, wherein in particular mechanical stresses can be attenuated and / or an optical effect can be changed.

[0018] Subject matter of the invention

[0019] This object is achieved in accordance with a first aspect by a method of the type mentioned in the introduction, in the case of which the optical component is formed, in particular curved, during the high-temperature bonding. As is generally customary, "forming" is understood to mean a deliberate change in shape, by contrast to a deformation, which is a non-deliberate plastic change in shape. The forming can in particular include deliberately curving the optical component or a face of the optical component.

[0020] During the high-temperature bonding or during the tempering above the glass transition temperature, the optical component becomes viscous and can be deformed. This "flowing" of the optical component can be utilized to deliberately

[0021] 2024P00012WO 11.09.25 SZ00393PCT change the shape of the optical component in the viscous state and, during this change in shape, from an e.g. cuboidal optical component before the high- temperature bonding, an optical component can be formed that is shaped in a different way, for example concavely or convexly curved. The additional degree of freedom provided when the partial bodies, i.e. the optical component, are / is heated to temperatures above the glass transition temperature is deliberately utilized in this aspect of the invention to bring the optical component into a desired shape.

[0022] When the optical component is cooling down after exceeding the glass transition temperature, temperature gradients arise in the optical component and, depending on the current temperature conditions and the temperature applied in the furnace in which the tempering is carried out, tensile and compressive forces occur. The inventors have used measurements to ascertain that, after the optical component has cooled down to room temperature, the tensile and compressive forces can also lead to a permanent deformation, in particular a curvature, of the optical component, and during this deformation a concavely and a convexly curved side of the optical component is formed. The deformation brought about during the cooling-down operation is, however, considerably less than the forming that can be realized in the viscous state.

[0023] However, by virtue of a suitable temperature profile while the optical component is cooling down, it is possible to form, i.e. deliberately deform, the optical component. If necessary, it is also possible to take into account, during the forming of the optical component in the viscous state above the glass transition temperature, the expected deformation of the optical component during the cooling-down operation, this deformation resulting in a face with a PV value of 100 pm or less after the high-temperature bonding being created from a plane face of the optical component before the high-temperature bonding.

[0024] In a variant, the partial bodies are placed onto a formed surface which is preferably concavely or convexly curved, and during the high-temperature

[0025] 2024P00012WO 11.09.25 SZ00393PCT bonding the optical component - in the viscous or partially viscous state - is let down onto the formed surface. In this case, the optical component is typically formed by letting it down under the effect of gravitational force, i.e. the dead weight of the optical component causes the optical component to let itself down onto the formed surface, the underside of the bottom partial body of the optical component taking on the geometry of the formed surface. The formed surface may have an e.g. spherical concave or convex curvature, but it is also possible for the formed surface to be a freeform face. If the optically effective surface is an aspherical surface, during the high-temperature bonding use should be made of a formed surface which is also an aspherical surface.

[0026] The formed surface may be the surface of a support to which the partial bodies are applied before they are fed into the tempering furnace. It is also possible for the formed surface to be the base of a mould which has side walls preventing the optical component, i.e. the partial bodies, from slipping or tilting. The support or the mould is produced from a heat-resistant material, for example a clay brick.

[0027] In a further refinement, the formed surface has a geometry corresponding to the geometry of an optically effective surface of the optical component. In the case of an optical component in the form of a mirror, the optically effective surface is that surface to which a reflective coating is applied. The letting down under the effect of gravitational force makes it possible to deliberately form an outer side in the form of the underside of the bottom partial body and adapt it to the geometry of the formed surface of the support or the base of the mould.

[0028] The bottom-partial-body surface, which is generally plane before the forming and the high-temperature bonding, is typically that surface to which, in the case of a mirror, the reflective coating is applied after reworking, e.g. by polishing. The formed surface is adapted or corresponds (in the form of a negative shape) to the geometry of the optically effective surface. If the later optically effective

[0029] 2024P00012WO 11.09.25 SZ00393PCT surface is concavely or convexly curved, the formed surface is also convexly or concavely curved and typically has the same radius of curvature.

[0030] If, before the forming, the joining face is aligned parallel to the partial-body surface that is deliberately deformed, i.e. formed, and lowered onto the formed surface during the forming, the joining face also typically follows the geometry of the optically effective surface. The optical-component surface that comes into contact with the formed surface during the forming, and also the joining face are typically plane before the high-temperature bonding. The optical component is typically held at a temperature or at temperatures above the glass transition temperature until the underside of the optical component has finished being let down onto the formed surface. To this end, it may be sufficient if the optical component is heated with a temperature change over time at a rate of for example approximately 50 K / h, the optical component typically needing to be held at a holding temperature above the glass transition temperature for a certain period of time.

[0031] As described above, after the cooling the optically effective surface is created on the formed optical component generally by mechanical processing, for example sanding or polishing. If the geometry of the surface on which the optically effective surface is created after the cooling also substantially corresponds to the geometry, i.e. the curvature, of the optically effective surface already before the processing, the material removal during the processing can be reduced. It is also possible to substantially uniformly remove material during the machining.

[0032] In a further variant, the formed surface has a PV value of at least 0.5 mm, preferably at least 1 mm, in particular at least 5 mm. As is generally customary, the PV value is understood to mean the spacing between the highest point and the lowest point of the surface profile of a formed surface, in relation to an initial profile in the form of a plane surface.

[0033] 2024P00012WO 11.09.25 SZ00393PCT The optical-component surface that comes into contact with the formed surface during the lowering has, after the lowering, a PV value corresponding to the PV value of the formed surface. The deformation, i.e. curvature, of the optical component on the surface that comes into contact with the formed surface, this deformation being caused by being let down, can be selected to be great enough to follow the curvature of the optically effective surface to which the reflective coating is applied.

[0034] As described above, a suitable temperature change over time during the tempering, i.e. during the cooling, of the optical component to temperatures below the glass transition temperature also makes it possible to have the effect of forming, i.e. deliberately deforming, the optical component, with the thereby achievable curvature being considerably smaller than in the case of the forming by gravitational force described above, i.e. it is only possible to create PV values of less than approximately 100 pm on the formed surface. Generally speaking, in this case, when placed on a support with a plane surface, the optical component or the partial bodies curve(s) concavely on a side facing the plane surface and convexly on a side facing away from the support, this being attributable to temperature gradients within the glass material during the cooling-down operation. This effect can be utilized deliberately to deform, i.e. curve, the optical component. The effect of the forming that takes place above the glass transition temperature is, however, in general considerably higher. The effect occurring during the cooling-down operation can therefore be ignored if it is appropriate to do so, in particular because the optical component is reworked after the high-temperature bonding in order to create the optically effective surface.

[0035] Besides the deformation of the optical component, i.e. of the partial bodies, it is also necessary to take into account that deformation of the support or of the mould during the tempering that is attributable to the thermal loading and

[0036] 2024P00012WO 11.09.25 SZ00393PCT pressure loading exerted by the partial bodies or the optical component resting thereon. It may in particular be expedient if, during the tempering in the coolingdown phase, during which the optical component is cooled down to room temperature from a temperature above the glass transition temperature, an intermediate stage, i.e. a holding step, is carried out at a predefined temperature, in order to bring the overall system, i.e. the optical component and the support or casting mould, to a uniform temperature. The holding temperature can lie for example in the order of magnitude of e.g. 700°C.

[0037] In a refinement of this variant, before the high-temperature bonding, a first connecting face of a first partial body and a second connecting face of a second partial body are brought into contact with one another and preferably connected to one another by wringing, the two partial bodies being connected to one another during the high-temperature bonding on the connecting faces so as to provide the joining face or one of the joining faces. The first connecting face of the first partial body and the second connecting face of the second partial body can be in the form of a plane, spherical, aspherical or freeform face.

[0038] It is favourable if the partial bodies are brought into contact on the connecting faces and connected to one another by wringing, before the high-temperature bonding is carried out. The wringing of two or more partial bodies made of glass material is a method that has been known for a long time for connecting two glass components to one another. In the case of wringing, the surfaces of two partial bodies that are sufficiently smooth are brought into close contact with one another generally at room temperature, the two connecting faces being connected to one another by van der Waals forces or by hydrogen bonds. This type of connection between the two partial bodies is reversible, i.e. the partial bodies connected to one another by wringing can be detached from one another again e.g. by a wedge applied to the connecting point: cf. also the article "Wafer direct bonding: tailoring adhesion between brittle materials”, A. Plo(3>l et al., Material Science and Engineering: R: Reports, Volume 25, Issues

[0039] 2024P00012WO 11.09.25 SZ00393PCT 1-2, 10 March 1999, p. 1-88. The subsequent high-temperature bonding makes it possible to considerably increase the bond strength and the stiffness of the optical component.

[0040] It can be expedient if the connecting faces and thus also the later joining face have / has a curvature, for example if cooling channels that are to have a constant spacing from a curved optically effective face are made there. In the variant described here, the connecting faces of the two partial bodies can be wring-bonded to one another and, during the high-temperature bonding, the forming of the optical component allows a joining face to be formed that deviates from the geometry of the connecting faces. For example, the forming of the optical component makes it possible to increase the curvature of the joining face or it is possible to decrease the curvature of the joining face, or the curvature of the connecting face can be compensated for, by the forming of the optical component.

[0041] In a refinement of this variant, before the high-temperature bonding, channels are formed on the first connecting face and / or on the second connecting face for a fluid to flow through, the channels preferably being formed by mechanical processing. The channels can be created for example by machining, e.g. by milling or sanding, on each connecting face. When the two partial bodies are connected along the connecting faces, the cross section of the channels is closed around the periphery. After the high-temperature bonding, the channels follow the curved joining face. If the curved optically used surface runs substantially parallel to the curved joining face, the channels can have a uniform, constant spacing from the optically used surface, without the two partial bodies needing to be connected to one another along curved connecting faces for this purpose. In this way, the processing times for the production of the optical component can be decreased, the yield can be increased and the reject rate can be reduced.

[0042] 2024P00012WO 11.09.25 SZ00393PCT In a further aspect of the invention, which in particular can be combined with the above-described aspect, before the connecting operation at least one defect, preferably a plurality of defects, particularly preferably in the form of particles, in particular in the form of polymer particles, resin particles or metal particles, is introduced between the partial bodies and / or, before the partial bodies are connected, local material removal is used to form at least one local depression on at least one connecting face of at least one of the partial bodies and, during the connecting operation, preferably by high-temperature bonding, in the region of at least one joining face a closed cavity is formed around the at least one defect and / or at the at least one local depression. The particles are typically microparticles or possibly nanoparticles.

[0043] In this variant, the connecting, i.e. the joining, of two or more partial bodies is utilized to form one or more closed cavities or holes in the optical component. The closed cavities can serve to attenuate material stresses and / or deliberately influence the geometry of the optically effective surface of the optical component and thus its optical effect. To this end, the closed cavities are typically located at a defined spacing, predefined by the position of the joining face, from the optically used region or from the optically effective surface. The local, closed cavities or holes are typically filled with air or partially with residues of the respective defect and therefore have a stress-attenuating effect and / or allow the deliberate local deformation of the surface geometry of the optically effective surface.

[0044] The closed cavities can be located in particular between the optically effective surface and a region at which mechanical stress is introduced in the direction towards the optically active surface. For example, the closed cavities can be located between an optically used portion of the optically effective surface on a front side of the optical component and on a back side of the optical component, at which the mechanical stresses are introduced. By reducing the mechanical stresses, the system performance can be increased. Moreover, it is possible, if

[0045] 2024P00012WO 11.09.25 SZ00393PCT appropriate, to relax the specifications for the optically used portion of the optically active surface, since a disturbance in the system can be avoided.

[0046] The defects prevent the partial bodies from connecting to one another in a locally delimited region around the defects on the joining face, as a result of which a closed cavity is produced between the connecting faces not locally connected to one another. In order to create or enhance a stress-attenuating effect of the closed cavities, it is favourable if the defects are compressed during the joining, for example during the high-temperature bonding. This is generally not the case with particles in the form of metallic balls or platelets and with balls or platelets made of glass material. In particular polymer particles, resin particles and, if appropriate, metal particles have proven to be favourable as the material for the defects because they are compressed when they are heated, but other materials can also be used for this. Polymer particles with a size distribution, which have a precisely defined mean diameter, i.e. a small variance in the particle size, are typically commercially available for a wide diameter range of e.g. approximately 100 nm to approximately 300 pm.

[0047] One or more of the closed cavities can also be formed by making a local depression in at least one of the connecting faces of the two partial bodies, by locally removing material on the connecting face. The material can be locally removed for example by laser processing or in another way, e.g. by machining, for example by sanding or by milling. The closed cavity is in this case formed by the connecting face of the other partial body covering the depression during the connecting operation along the joining face. By contrast to the formation of channels through which a temperature-control medium can flow, the cavities formed during the connecting are closed in the present case.

[0048] The partial bodies are connected, i.e. joined, by a joining process which makes it possible to permanently connect the partial bodies over the entire service life of the optical component. The joining process can in particular be the above-

[0049] 2024P00012WO 11.09.25 SZ00393PCT described high-temperature bonding, but it is fundamentally also possible to connect the partial bodies permanently to one another e.g. by bonding at lower temperatures, if appropriate without exceeding the glass transition temperature in the process. A prerequisite for the method described here is that the design of the optical component allows it to be divided along the, or at least one, face that corresponds to the later joining face.

[0050] In a variant, before the connecting operation, the defects are positioned at predefined positions on a connecting face of at least one partial body. The positioning preferably takes place in automated fashion; for example, the particles can be applied to the connecting face using a sputtering process or e.g. using a template. It is favourable if the defects are positioned at defined positions and not in a statistic distribution on the connecting face.

[0051] In a further variant, the closed cavities have a maximum extent perpendicular to the joining face of no more than 50 pm, preferably no more than 30 pm, in particular no more than 10 pm, and / or they have a ratio of width to height of at least 50: 1 , preferably at least 100: 1 , in particular at least 500: 1. In this case, the width of the closed cavities is measured parallel to the joining face and denotes the maximum extent of each cavity between two points of the cavity parallel to the joining face; the height of the closed cavities is measured perpendicularly in relation to the joining face and denotes their maximum extent between two points perpendicularly in relation to the joining face. By contrast to the abovedescribed first aspect of the invention, the joining face in the example shown generally extends in plane fashion. The connecting faces are also generally in the form of plane faces.

[0052] The diameter of the defects, i.e. particles, before the connecting operation typically corresponds to the height of the closed cavities, i.e. the height of the closed cavities generally corresponds to the order of magnitude of the diameter of the defects, i.e. particles, before they are compressed. If the cavities and thus

[0053] 2024P00012WO 11.09.25 SZ00393PCT the defects have a relatively small height or a relatively small diameter, the partial bodies can be wring-bonded to one another before the connecting operation, as described above in connection with the first aspect of the invention. Generally speaking, before the connecting operation the partial bodies are aligned relative to one another before being connected to one another along the joining face(s).

[0054] By contrast to the height, the width of the closed cavities is generally considerably larger than the diameter of the defects. In general, the ratio between the maximum width of the cavities and the maximum height of the cavities, i.e. the aspect ratio, lies in the above-specified range of values. Since the size of the defects substantially establishes the dimension of the closed cavities, a wide range of sizes for the closed cavity can be selected.

[0055] In spite of the relatively small defect that is generally compressed during the connecting operation, the two connecting faces are generally not connected to one another over a relatively large area around the defect along the joining face, which is why a closed cavity with a relatively large width is formed. Since a small height of the cavity is sufficient for the stress-attenuating effect, a closed cavity with such an aspect ratio is especially suitable for creating a stressattenuating effect over a relatively large area or width. For this purpose, the joining face is preferably aligned substantially perpendicularly in relation to the direction in which the mechanical stresses are introduced into the material of the optical component.

[0056] In a further variant, the defects are introduced with a lateral offset from one another between any two of the partial bodies, with the result that the closed cavities are formed with a lateral offset from one another on at least two joining faces, the closed cavities of a first joining face preferably running at least partially between the laterally offset closed cavities of a second joining face. For the mechanical stability of the optical component, it is typically necessary for

[0057] 2024P00012WO 11.09.25 SZ00393PCT directly adjacent closed cavities to have a sufficient lateral spacing from one another. In the region between the closed cavities, however, no stressattenuating effect is obtained. It is therefore favourable if the stress-attenuating effect is enhanced by forming closed cavities along a second joining face which are laterally offset and at least partially fill the gaps between the closed cavities of the first joining face, in order to enhance the stress-attenuating effect.

[0058] In a variant, while the at least one closed cavity is being formed, a gas, preferably air, is trapped in the closed cavity. As described above, the trapped gas, which is typically air, can have a stress-attenuating effect. The gas trapped in the closed cavity has a pressure which typically corresponds to the ambient pressure when the optical component is being produced or when the connecting faces of the partial bodies are being brought into contact. Ambient pressure when the optical component is being produced is typically atmospheric pressure. If, during operation, the optical component is in service in a semiconductor technology apparatus with an ambient pressure which deviates from the pressure prevailing during the production or the pressure present in the closed cavity, the pressure difference can lead to a depression or deformation of the material of the optical component located between the closed cavity and an optically effective surface of the optical component.

[0059] If, during operation of the optical component, the pressure in the closed cavity is greater than the ambient pressure, the result is typically a local deformation in the form of a local elevation on the optically effective surface. If the spacing between the closed cavity and the optically effective surface, the extent of the closed cavity and the ambient conditions, e.g. the pressure and the temperature, during production or when the gas is being trapped in each cavity and during operation of the optical component are known, the local deformation effect caused by the trapped gas can be calculated or predicted.

[0060] Correspondingly, the parameters for the production of each closed cavity can be selected such that a desired deformation effect on the optical surface is set.

[0061] 2024P00012WO 11.09.25 SZ00393PCT It is fundamentally also possible to make cavities in glass material by irradiation with ultra-short-pulse lasers, without carrying out a joining process; cf. for example the article "Void formation in glasses", T. Hashimoto et al., New Journal of Physics, 2007, no. 8, page 253ff. or the article "Well-controlled femtosecond laser inscription of periodic void structures in porous glass for photonic applications", Optics express, 2017, no. 26, pages 33261-33270. However, in these cases the state of introduction of the air or of the gas present in the holes, i.e. closed cavities, is not known and cannot be readily checked.

[0062] In a further variant, the partial bodies are made of fused silica, preferably of titanium-doped fused silica, of a glass ceramic or of silicon. Titanium-doped fused silica and certain glass ceramics have a particularly low coefficient of thermal expansion and are therefore suitable in particular for the production of substrates for EUV mirrors. Silicon can also be used as material for the substrate of EUV mirrors, in particular if they are operated at grazing incidence. Partial bodies of silicon can also be detachably connected to one another by wring-bonding and then permanently connected to one another by high- temperature bonding. For a potential in-line process monitoring during the wring-bonding and for an inspection, in this case a thermal imaging camera, for example in the form of an SWIR camera, can be used. It should be understood that the optical component can also be produced from partial bodies made of other suitable materials that can be connected to one another by high- temperature bonding.

[0063] A further aspect of the invention relates to an optical component, preferably a mirror, in particular for reflecting EUV radiation, which is produced by the above-described method. The optical component in the form of a mirror has a reflective coating on an outer surface forming the optically effective surface. The reflective coating is typically applied to the outer surface, generally to a portion of the outer, optically effective surface, only after the partial bodies have been

[0064] 2024P00012WO 11.09.25 SZ00393PCT connected. If the partial bodies are made of glass material, the reflective coating is generally a multilayer coating which has a plurality of alternating layers with different refraction indices. In particular if the optical component is to be formed, in particular curved, during the high-temperature bonding, it has proven to be favourable if it does not have an excessive thickness, which should lie in the order of magnitude of less than one metre.

[0065] In one embodiment of the optical component, the glass material has striations which follow the geometry of a curved optically used surface of the optical component and / or at least one joining face. On an optical component produced from fused silica or titanium-doped fused silica, it is generally possible to directly prove that at least one outer surface and / or joining face has been formed, i.e. curved, during the high-temperature bonding: Owing to the production, these glass materials have striations (striae) which run in the partial bodies before the connection substantially in plane-parallel planes perpendicularly in relation to the axial direction of the glass body. If the joining face or the outer surfaces are curved during the high-temperature bonding, the orientation of the striations also changes, i.e. they follow the curvature of the optical component. If channels with e.g. a rectangular cross section are made in the material of the optical component, the striations also run parallel to the walls on the top or bottom side of the channels and perpendicularly in relation to the side walls of the channels, this being proof that the tempering has taken place only after the channels have been made. In the case of other materials which have a characteristic profile of the striations, it is also possible to directly prove on the optical component that it has been formed, i.e. curved, during the high- temperature bonding.

[0066] In a further embodiment, the optical component has, in the region of the at least one joining face, closed cavities which preferably have a maximum extent perpendicular to the joining face of no more than 50 pm, particularly preferably no more than 30 pm, in particular no more than 20 pm, and / or preferably have a

[0067] 2024P00012WO 11.09.25 SZ00393PCT ratio of width to height of at least 50:1 , particularly preferably at least 100:1 , in particular at least 500:1 . As described above, such cavities can be created by introducing defects, in particular particles, between the partial bodies, around which defects or particles the closed cavities are formed.

[0068] A further aspect of the invention relates to a semiconductor technology apparatus, in particular an EUV lithography apparatus, comprising: at least one optical component designed as described above, wherein preferably in the at least one closed cavity of the optical component a gas, in particular air, is trapped and the optical component in the semiconductor technology apparatus is located in a vacuum environment, the pressure of which is lower than a pressure of the gas in the closed cavity, with the result that, on an optically effective surface of the optical component, in the region of the at least one closed cavity at least one local elevation is formed.

[0069] For the purposes of this application, a semiconductor technology apparatus is understood as meaning a lithographic optical system, i.e. an optical system that can be used in the field of lithography. Apart from a lithography apparatus, which serves for the production of semiconductor components, the apparatus may be for example an inspection system for the inspection of a photomask used in a lithography apparatus (hereinafter also referred to as a reticle), for the inspection of a semiconductor substrate to be structured (hereinafter also referred to as a wafer) or a metrology system, which is used for measuring a lithography apparatus or parts thereof, for example for measuring a projection system.

[0070] The semiconductor technology apparatus can be operated in particular with used radiation in the form of EUV radiation. EUV radiation is understood to mean radiation in a wavelength range of between about 5 nm and about 30 nm, for example at 13.5 nm. Since EUV radiation is absorbed to a great extent by most known materials, the EUV radiation is typically routed through the

[0071] 2024P00012WO 11.09.25 SZ00393PCT semiconductor lithography apparatus using optical components in the form of EUV mirrors.

[0072] As described above, the pressure difference between the pressure of the gas trapped in each cavity and the lower pressure in the vacuum environment of the optical component makes it possible to form at least one local elevation on an optically effective surface of the optical component in the region of the at least one closed cavity. Each local elevation makes it possible to deliberately influence the optical effect of the optical element. The size of the local elevation formed in this way can in particular be smaller than the smallest possible local elevation producible when the optically effective surface is being processed by a processing tool.

[0073] Further features and advantages of the invention emerge from the following description of exemplary embodiments of the invention on the basis of the figures of the drawing, which show details essential to the invention, and from the claims. The individual features may be realized in each case individually by themselves or as a plurality in any desired combination in a variant of the invention.

[0074] Drawing

[0075] Exemplary embodiments are illustrated in the schematic drawing and are explained in the following description. In the figures:

[0076] Fig. 1 schematically shows a meridional section of a projection exposure apparatus for EUV projection lithography,

[0077] Fig. 2a shows a schematic illustration of two partial bodies placed onto a formed surface of a support before the high-temperature bonding,

[0078] 2024P00012WO 11.09.25 SZ00393PCT Fig. 2b shows a schematic illustration of a curved optical component after the high-temperature bonding of the two partial bodies,

[0079] Fig. 3 shows a schematic illustration similar to Fig. 2a, in which the two partial bodies have been placed onto a formed surface of a base of a casting mould,

[0080] Fig. 4a, b show schematic illustrations of two partial bodies, i.e. an optical component, resting on a plane surface during the high- temperature bonding, before and after the cooling-down operation,

[0081] Fig. 5a-d show schematic illustrations of method steps for producing closed cavities in an optical component,

[0082] Fig. 6a, b show schematic illustrations of the optical component in Fig. 5a-d and a further optical component which has additional, laterally offset closed cavities along a joining face, and

[0083] Fig. 7a-d show schematic illustrations of method steps for producing an optical component with closed cavities and an optical component produced in this way in operation in a vacuum environment.

[0084] In the following description of the drawings, the same reference signs are used for identical or functionally identical components.

[0085] The essential component parts of an optical arrangement for EUV lithography in the form of a microlithographic projection exposure apparatus 1 are described by way of example below with reference to fig. 1. The description of the basic setup of the projection exposure apparatus 1 and its component parts should not be understood to have a limiting effect.

[0086] 2024P00012WO 11.09.25 SZ00393PCT One embodiment of an illumination system 2 of the projection exposure apparatus 1 has, in addition to a light or radiation source 3, an illumination optical unit 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 may also be provided in the form of a module separate from the rest of the illumination system. In this case, the illumination system does not comprise the light source 3.

[0087] A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable, in particular in a scanning direction, by way of a reticle displacement drive 9.

[0088] For explanation purposes, a Cartesian xyz coordinate system is depicted in Fig. 1. The x-direction runs perpendicularly into the plane of the drawing. The y- direction runs horizontally and the z-direction runs vertically. The scanning direction runs in the y-direction in Fig. 1 . The z-direction runs perpendicularly in relation to the object plane 6.

[0089] The projection exposure apparatus 1 comprises a projection system 10. The projection system 10 is used to image the object field 5 into an image field 11 in an image plane 12. A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable in particular in the y-direction by way of a wafer displacement drive 15. The displacement on the one hand of the reticle 7 by way of the reticle displacement drive 9 and on the other hand of the wafer 13 by way of the wafer displacement drive 15 can take place in such a way as to be synchronized with one another.

[0090] The radiation source 3 is an EUV radiation source. The radiation source 3 emits in particular EUV radiation 16, which is also referred to below as used radiation, illumination radiation or illumination light. The used radiation has in particular a

[0091] 2024P00012WO 11.09.25 SZ00393PCT wavelength in the range between 5 nm and 30 nm. The radiation source 3 can be a plasma source, for example an LPP (Laser Produced Plasma) source or a GDPP (Gas Discharge Produced Plasma) source. It can also be a synchrotronbased radiation source. The radiation source 3 may be a free electron laser (FEL).

[0092] 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 hyperboloidal reflection surfaces. The illumination radiation 16 can be incident on the at least one reflection surface of the collector mirror 17 with grazing incidence (Gl), i.e. at angles of incidence of greater than 45°, or with normal incidence (N I), i.e. at angles of incidence of less than 45°. The collector mirror 17 can be structured and / or coated, firstly, for optimizing its reflectivity for the used radiation and, secondly, for suppressing extraneous light.

[0093] Downstream of 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 constitute a separation between a radiation source module, comprising the radiation source 3 and the collector mirror 17, and the illumination optical unit 4.

[0094] The illumination optical unit 4 comprises a deflection mirror 19 and, downstream thereof in the beam path, a first facet mirror 20. The deflection mirror 19 may be a plane deflection mirror or, alternatively, a mirror with a beam-influencing effect that goes beyond the pure deflection effect. As an alternative or in addition, the deflection mirror 19 may be in the form of a spectral filter that separates a used light wavelength of the illumination radiation 16 from extraneous light of a wavelength deviating therefrom. The first facet mirror 20 comprises a multiplicity of individual first facets 21 , which are also referred to below as field facets. Only some of these facets 21 are shown in Fig. 1 by way of example. In the beam

[0095] 2024P00012WO 11.09.25 SZ00393PCT path of the illumination optical unit 4, a second facet mirror 22 is disposed downstream of the first facet mirror 20. The second facet mirror 22 comprises a plurality of second facets 23.

[0096] The illumination optical unit 4 thus forms a doubly faceted system. This basic principle is also referred to as a fly's eye condenser (fly's eye integrator). The second facet mirror 22 is used to image the individual first facets 21 into the object field 5. The second facet mirror 22 is the last beam-shaping mirror or, in fact, the last mirror for the illumination radiation 16 in the beam path upstream of the object field 5.

[0097] The projection system 10 comprises a plurality of mirrors Mi, which are consecutively numbered in accordance with their arrangement in the beam path of the projection exposure apparatus 1 .

[0098] In the example illustrated 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 similarly possible. In the example shown, the penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection system 10 is a doubly obscured optical unit. The projection optical unit 10 has an image-side numerical aperture which is greater than 0.4 or 0.5 and which can also be greater than 0.6 and which can be for example 0.7 or 0.75.

[0099] Just like the mirrors of the illumination optical unit 4, the mirrors Mi can have a highly reflective coating for the illumination radiation 16.

[0100] Fig. 2a, b show an optical component in the form of a mirror Mi of the projection system 10 while it is being produced. The mirror has a first, substantially flat partial body 25 and a second partial body 26. In the example shown, the two partial bodies 25, 26 are made of a glass material in the form of titanium-doped

[0101] 2024P00012WO 11.09.25 SZ00393PCT fused silica, but they may also be made of a different material with a low coefficient of thermal expansion. In the example shown, the two partial bodies 25, 26 are circular-cylindrical, wherein the cylinder axes, i.e. the axial direction, of the two partial bodies 25, 26 runs parallel to the direction of gravitational force, which corresponds to the Z-direction of an XYZ coordinate system. In Fig. 2a, the two partial bodies 25, 26 each have a plane top side 25a, 26b and a plane underside 25b, 26b. The top side 25a of the first partial body 25 and the underside 26b of the top partial body 26 form two connecting faces 25a, 26a, on which the partial bodies 25, 26 rest against one another. The underside 25b of the first partial body 25 and the top side 26a of the second partial body 26 form the outer surfaces of the mirror Mi.

[0102] The top partial body 26 in Fig. 2a has, on the connecting face 26b, a plurality of channels 27 through which a fluid is intended to flow. The channels 27 were made in the glass material of the second partial body 26 in a preceding method step by machining, more specifically by sanding.

[0103] In the example shown in Fig. 2a, the two partial bodies 25, 26 are in contact with one another on the plane connecting faces 25a, 26b and are detachably connected to one another by wringing. The two wring-bonded partial bodies 25, 26 are placed onto a support 28 for the connection and inserted into a tempering furnace for carrying out the high-temperature bonding. In the tempering furnace, the two partial bodies 25, 26 are heated to a temperature above the glass transition temperature, in the present case approximately 1000°C, the glass material being fused in the region of the two connecting faces 25a, 26b and the two partial bodies 25, 26 being connected to form the mirror Mi shown in Fig. 2b, so as to provide a joining face 29.

[0104] In the example described in Fig. 2a, b, the high-temperature bonding is additionally utilized to form, more specifically to curve, the mirror Mi. To this end, before being connected the two partial bodies 25, 26 are placed onto a

[0105] 2024P00012WO 11.09.25 SZ00393PCT formed, in the example shown convexly curved, surface 30 of the support 28. During the high-temperature bonding, the two partial bodies 25, 26, i.e. the mirror Mi being formed, are / is formed in the viscous state, by being let down onto the formed surface 30. During the letting-down operation, the underside 25b of the first partial body 25 assumes the geometry of the formed surface 30 of the support 28. In the example shown, the formed surface 30 of the support 28 has a convex geometry corresponding to the concave geometry of an optically effective surface 31 of the mirror Mi, illustrated in Fig. 2b. To allow this, the formed surface 30 of the support 28 has a PV value of at least 0.5 mm, at least 1 mm or at least 5 mm. In the example shown, the PV value corresponds to the maximum height H of the curved surface 30 in relation to a plane portion of the support 28.

[0106] As Fig. 2b shows, the optically effective surface 31 in Fig. 2b runs underneath the outer surface 25b, which was curved during the high-temperature bonding, of the first partial body 25. Since the curvature of the outer surface 25b of the first partial body 25 corresponds to the curvature of the optically effective surface 31 , it can be formed by uniform material removal on the first partial body 25.

[0107] As Fig. 2b also shows, the channels 27 through which a fluid is intended to flow also follow the joining face 29 that was curved during the high-temperature bonding. Since the optically effective surface 31 runs parallel to the concavely curved outer surface 25b of the mirror Mi, the channels 27 have a constant spacing d from the later optically effective surface 31 . In a subsequent step, a reflective coating not depicted in Fig. 2a, b is applied to the optically effective surface 31 in order to finish the production of the mirror Mi.

[0108] In the case of the mirror Mi shown in Fig. 2b, the channels 27 follow the curvature of the joining face 29, although the connecting faces 25a, 26b of the two partial bodies 25, 26 in Fig. 2a are plane. By curving the glass material of

[0109] 2024P00012WO 11.09.25 SZ00393PCT the mirror Mi during the high-temperature bonding, striations 32 present in the glass material and running in mutually parallel XY-planes in Fig. 2a, one of which is depicted in Fig. 2a, are also curved and run parallel to the curved joining face 29, as shown in Fig. 2b.

[0110] In the way described in connection with Fig. 2a, b, it is possible to create not only mirrors Mi with concavely or convexly curved outer faces 25b, 26a, but also mirrors Mi of which the outer faces 25b, 26a have fundamentally any desired shape. Fig. 3 shows the two partial bodies 25, 26 placed on a formed surface 30 designed as a freeform face, which forms the base of a casting mould 33. A side wall 34 around the periphery of the casting mould 33 prevents the two partial bodies 25, 26 from laterally slipping while being let down under the effect of gravitational force. In the example shown in Fig. 3, the formed surface 30 on the base of the casting mould 33 is also designed such that it corresponds to the geometry of an optically effective surface of the mirror Mi to be produced.

[0111] Fig. 4a, b show a mirror Mi which has been placed onto a plane support 28 during the cooling-down operation, after the glass transition temperature was exceeded during the high-temperature bonding. Fig. 4a indicates the isotherms of the temperature distribution in the mirror Mi in the second partial body 26. As the mirror Mi cools down, volume regions radially on the outside are cooled down more quickly and therefore solidify more quickly than volume regions radially on the inside. The effect of this is that, in the glass material of the mirror Mi, mechanical stresses arise which act substantially radially in the direction towards the centre axis of the substantially cylindrical partial bodies 25, 26, as indicated in Fig. 4a.

[0112] The mechanical stresses have the effect that the mirror Mi is made to curve as it continues to cool down, as can be seen in Fig. 4b. The outer side 25b of the first partial body 25, on which the optically active surface is to be formed, is convexly curved in the process, whereas the outer surface 26a of the second

[0113] 2024P00012WO 11.09.25 SZ00393PCT partial body 26 is concavely curved. The PV value of the convexly curved outer surface, i.e. the height hi , in relation to the lateral edge of the mirror Mi, is approximately 100 pm in the example shown, and the height h2 of the concavely curved outer surface 26a of the mirror Mi is approximately 70 pm. The diameter of the mirror Mi shown in Fig. 4a, b was approximately 400 mm. The effect, illustrated in Fig. 4a, b, of the curvature of the mirror Mi as it cools down is therefore relatively small and generally it is not possible to adapt the geometry of the outer surfaces 25b, 26a to the curved optically effective surface of the mirror Mi.

[0114] Fig. 5a-d show multiple steps in the production of a mirror Mi, which has by way of example four closed cavities 35a-d for attenuating mechanical stresses, as shown in Fig. 5d.

[0115] In the method step shown in Fig. 5a, firstly a blank made of a glass material is divided into two partial bodies 25, 26 along a plane face. Then, on the top side 25a of the lower partial body 25, four defects 36a-d are positioned at predefined positions of the top side 25a of the lower partial body 25, as illustrated in Fig. 5b. The defects 36a-d in this case have the same lateral spacings from one another. In the example shown, the defects 36a-d are particles, for example polymer particles, which have a diameter in the order of magnitude of e.g. approximately 5 pm. For the sake of clarity, in Fig. 5b-d the polymer particles are illustrated considerably larger than they are in reality. Instead of polymer particles, it is also possible to use resin particles, metal particles, or possibly dust particles.

[0116] In a method step illustrated in Fig. 5c, the second partial body 26 is placed onto the first partial body 25, with the result that the defects 36a-d are introduced between the two partial bodies 25, 26. The second partial body 26 is in this case aligned suitably relative to the first partial body 25. By contrast to what is illustrated in Fig. 5c, the two partial bodies 25, 26 in spite of the defects 36a-d

[0117] 2024P00012WO 11.09.25 SZ00393PCT are wring-bonded to one another on the two oppositely situated connecting faces 25a, 26b.

[0118] In a subsequent step, the two partial bodies 25, 26 are connected to one another by high-temperature bonding along the two connecting faces 25a, 26b that are in contact, a joining face 29 being formed. In this case, formed on the joining face 29 or in the region of the joining face 29 and around each defect 36a-d is a respective closed cavity 35a-d, at which the two connecting faces 25a, 26b are not connected to one another. The defects 36a-d in the form of the polymer particles shrink in the process, i.e. they are compressed, as is evident by comparing Fig. 5c and Fig. 5d.

[0119] The size of each closed cavity 35a-d can be set by the diameter of the defects 36a-d. In the example shown in Fig. 5d, the closed cavities 35a-d have a maximum extent perpendicular to the joining face 29 of no more than 50 pm, no more than 30 pm, more specifically no more than 20 pm. The ratio of maximum width b along the plane joining face 29 to the maximum height h of the closed cavities 35a-d is at least 50: 1 , at least 100: 1 , in particular at least 500: 1 .

[0120] The closed cavities 35a-d with the above-described aspect ratio make it possible to effectively attenuate mechanical stresses introduced into the glass material of the mirror Mi perpendicularly in relation to the underside 25b of the first partial body 25, as indicated by arrows in Fig. 6a. In this way, the optically active surface 25a of the mirror Mi or the optically active portion of the surface 25a to which a reflective coating 37 has been applied is effectively protected against the action of the mechanical stresses.

[0121] Since the closed cavities 35a-d cannot be positioned as close to one another as desired in the lateral direction, i.e. parallel to the joining face 29, it is favourable to form a further joining face 29' between the first partial body 25 and a third

[0122] 2024P00012WO 11.09.25 SZ00393PCT partial body 38. The third partial body 38 is connected to the first partial body 25 in the way described above, as illustrated in Fig. 6b.

[0123] Defects 36e-g are also introduced between the first partial body 25 and the third partial body 38 and have the effect that cavities 35e-g closed during the high- temperature bonding are formed along the further joining face 29'. The closed cavities 35e-g on the further joining face 29' are laterally offset from the closed cavities 35a-d of the joining face 29, more specifically they run at least partially laterally offset between each two adjacent closed cavities 35a-d of the joining face 29. In this way, it is also possible to attenuate mechanical stresses introduced into the material of the mirror Mi between the closed cavities 35a-d of the joining face 29, as indicated in Fig. 6b by three further arrows.

[0124] Fig. 7a-c show method steps in the production of a mirror Mi, in order to form closed cavities 35a, b on the joining face 29 between the two partial bodies 25, 26 similarly to Fig. 5a-d. In this case, a first closed cavity 35a is produced as described in Fig. 5a-d by introducing a particle 36, in the example shown a metal particle, between the two partial bodies 25, 26, as illustrated in Fig. 7a. Around the particle 36, the first closed cavity 35a is formed by high-temperature bonding in the region of the joining face 29 during the connecting, illustrated in Fig. 7b, of the two partial bodies 25, 26.

[0125] A second closed cavity 35b is formed in the example shown in Fig. 7a-c in that a local depression 39 is formed on the connecting face 26b of the second partial body 26 by local material removal before the two partial bodies 25, 26 are connected, as is evident in Fig. 7a. In the example shown, the depression 39 is substantially cylindrical, but may also have a different geometry. The depression 39 can be produced for example by laser processing but also by machining, e.g. by milling or sanding. When the two partial bodies 25a, 25b are being connected by high-temperature bonding along the joining face 29, the

[0126] 2024P00012WO 11.09.25 SZ00393PCT second closed cavity 35b is formed at the depression 39 or in the region of the depression 39, as is evident in Fig. 7b.

[0127] As illustrated in Fig. 7c, the top side 26a of the second partial body 26, which is the surface that in a later point in time of the processing constitutes the optically effective surface of the mirror Mi, is processed with a tool 40 in order to create a desired surface geometry, which in the example shown is a concave, spherical surface geometry. Then, a reflective coating 37 is applied to the concavely curved surface 26a of the second partial body 26, as described above in connection with Fig. 6a.

[0128] The production of the mirror Mi in the steps shown in Fig. 7a-c was carried out under production conditions Zo(po, To) at an ambient pressure po corresponding to atmospheric pressure. The steps illustrated in Fig. 7a and Fig. 7c were carried out at an ambient temperature To corresponding to room temperature (21 °C); the high-temperature bonding step described in Fig. 7b was carried out at an ambient temperature To higher than room temperature. The surrounding area of the two partial bodies 25, 26 contained a gas, typically air, in particular in the step described in Fig. 7a in which the two partial bodies 25, 26 are brought into contact with one another. While the two partial bodies 25, 26 are being brought into contact along the connecting faces 25a, 26b, the air present in the surrounding air is trapped in the closed cavities 35a, 35b. The air trapped in the closed cavities 35a, 35b therefore typically has a pressure po corresponding to the ambient pressure during the production of the mirror Mi.

[0129] Fig. 7d shows the mirror Mi, which is in service in the projection exposure apparatus 1 in Fig. 1 under operating conditions Zi (pi , Ti). The temperature Ti corresponding to the operating temperature is substantially room temperature, i.e. 21 °C, but the ambient pressure pi under operating conditions is considerably lower than the ambient pressure po during the production of the mirror Mi, since the mirror Mi during operation of the projection exposure

[0130] 2024P00012WO 11.09.25 SZ00393PCT apparatus 1 is located in a vacuum environment 42. Owing to the pressure difference between the pressure po inside each closed cavity 35a, 35b and the ambient pressure pi in the vacuum environment 42, the material of the second partial body 26 is depressed on the top side 26a of the second partial body 26 to which the reflective coating 37 has been applied. During the depressing, local elevations 41 a, 41 b are formed in the region of the closed cavities 35a, 35b on the top side 26a of the second partial body 26.

[0131] The height of each local elevation 41 a, 41 b substantially depends on, besides the pressure difference pi - po, what spacing D the closed cavities 35a, 35b or the joining face 29 have or has from the top side 26a of the second partial body 26. The width, or the lateral extent, of each local elevation 41 a, 41 b depends on the width bi , b2 of the respective closed cavity 35a, 35b. The width bi of the closed cavity 35a in which the particle 35a is located can be predefined in the way described above; the width b2 of the closed cavity 35b formed at the depression 39 can be predefined when the machining for producing the depression 39 is being carried out.

[0132] The trapping of air bubbles in the closed cavities 35a, 35b given known production conditions Zo(po, To) makes it possible to deliberately create local elevations 41 a, 41 b, etc. of which the lateral extent, i.e. width bi , b2, is smaller than the sub-aperture of the tool 40 used to process the top side 26a of the second partial body 26. If the production conditions Zo(po, To) when the air or gas bubbles are being introduced into the closed cavities 35a, 35b, the operating conditions Zi(pi , Ti) and the spacing D between the joining face 29 and the top side 26a of the second partial body 26 and the width bi , b2 of each closed cavity 35a, 35b are known in advance, the extent to which the depressions occur can be calculated in advance or used to predict the geometry of the local elevation 41 a, 41 b in the operating state. It should be understood that it is favourable to measure the surface geometry of the top side 26a in the operating state before the mirror Mi is installed in the projection exposure

[0133] 2024P00012WO 11.09.25 SZ00393PCT apparatus, the mirror Mi typically being introduced into a vacuum environment for the measurement. Such a measurement can optionally also be carried out in situ, in order to measure the exact geometry of the local elevations 41 a, 41 b and in this way be able to predict the optical effect of the local elevations 41a, 41 b as precisely as possible.

[0134] It should be understood that optical components different from the mirror Mi described above can also be produced in the way described here. In particular, the partial bodies 25, 26, 38 can also be made of other materials that can be connected to one another by high-temperature bonding.

[0135] 2024P00012WO 11.09.25 SZ00393PCT

Claims

Patent claims1 . Method for producing an optical component, preferably a mirror, in particular an EUV mirror (Mi), comprising: providing at least two partial bodies (25, 26, 38), preferably made of at least one glass material, and connecting the at least two partial bodies (25, 26, 38) to form the optical component while providing at least one joining face (29, 29') by high- temperature bonding, characterized in that during the high-temperature bonding, the optical component is curved.

2. Method according to Claim 1 , wherein the partial bodies (25, 26) are placed onto a formed surface (30) which is preferably concavely or convexly curved, and during the high-temperature bonding the optical component is let down onto the formed surface (30).

3. Method according to Claim 2, wherein the formed surface (30) has a geometry corresponding to the geometry of an optically effective surface (31 ) of the optical component.

4. Method according to Claim 2 or 3, wherein the formed surface (30) has a PV value of at least 0.5 mm, preferably at least 1 mm, in particular at least 5 mm.

5. Method according to any of the preceding claims, wherein, before the high- temperature bonding, a first connecting face (25a) of a first partial body (25) and a second connecting face (26b) of a second partial body (26) are brought into contact with one another and preferably connected to one another by wringing, the two partial bodies (25, 26) being connected to one2024P00012WQ 11.09.25 SZ00393PCTanother during the high-temperature bonding on the connecting faces (25a, 26b) so as to provide the joining face (29).

6. Method according to Claim 5, wherein, before the high-temperature bonding, channels (27) are formed on the first connecting face (25a) and / or on the second connecting face (26b) for a fluid to flow through, the channels (27) preferably being formed by mechanical processing.

7. Method for producing an optical component, preferably a mirror, in particular an EUV mirror (Mi), comprising: providing at least two partial bodies (25, 26, 38), preferably made of at least one glass material, and connecting the at least two partial bodies (25, 26, 38) to form the optical component while providing at least one joining face (29, 29'), characterized in that before the partial bodies (25, 26, 38) are connected, at least one defect, preferably a plurality of defects, particularly preferably in the form of particles (36a-d, 36e-g, 36), in particular in the form of polymer particles, resin particles or metal particles, is introduced between the partial bodies (25, 26, 38), and / or before the partial bodies (25, 26) are connected, local material removal is used to form at least one local depression (39) on at least one connecting face (26b) of at least one of the partial bodies (25, 26), and during the connecting operation, preferably by high-temperature bonding, in the region of at least one joining face (29, 29') a closed cavity (35a-d, 35e-g) is formed around the at least one defect and / or at the at least one local depression (39).2024P00012WO 11.09.25 SZ00393PCT8. Method according to Claim 7, wherein, before the connecting operation, the defects are positioned at predefined positions on a connecting face (25a) of at least one partial body (25, 26, 38).

9. Method according to either of Claims 7 and 8, wherein the closed cavities (35a-d, 35e-g) have a maximum extent perpendicular to the joining face (29, 29') of no more than 50 pm, preferably no more than 30 pm, in particular no more than 20 pm, and / or a ratio of width (b) to height (h) of at least 50:1 , preferably at least 100:1 , in particular at least 500:1 .

10. Method according to any of Claims 7 to 9, wherein the defects (36a-d, 36e- g) are introduced with a lateral offset from one another between any two of the partial bodies (25, 26; 25, 38), with the result that the closed cavities (35a-d, 35e-g) are formed with a lateral offset from one another on at least two joining faces (29, 29'), the closed cavities (35a-d) of a first joining face (29) preferably running at least partially between the laterally offset closed cavities (35e-g) of a second joining face (29').11 . Method according to any of Claims 7 to 10, wherein, while the at least one closed cavity (35a-d, 35e-g) is being formed, a gas, preferably air, is trapped in the closed cavity (35a-d, 35e-g).

12. Method according to any of the preceding claims, wherein the partial bodies (25, 26, 38) are made of fused silica, preferably titanium-doped fused silica, a glass ceramic or silicon.

13. Optical component, preferably mirror, in particular EUV mirror (Mi) for reflecting EUV radiation (16), produced by a method according to any of the preceding claims.2024P00012WO 11.09.25 SZ00393PCT14. Optical component according to Claim 13, wherein the glass material has striations (32) which follow the geometry of a curved optically used surface (31 ) of the optical component and / or at least one joining face (29, 29').

15. Optical component according to either of Claims 13 and 14 which, in the region of the at least one joining face (29, 29'), has closed cavities which preferably have a maximum extent perpendicular to the joining face (29, 29') of no more than 50 pm, particularly preferably no more than 30 pm, in particular no more than 20 pm, and / or preferably have a ratio of width (b) to height (h) of at least 50:1 , particularly preferably at least 100:1 , in particular at least 500:1 .

16. Semiconductor technology apparatus (1 ) comprising: at least one optical component according to any of Claims 13 to 15, wherein preferably in the at least one closed cavity (35a, 35b) of the optical component a gas, in particular air, is trapped and the optical component in the semiconductor technology apparatus (1 ) is located in a vacuum environment (42), the pressure (pi) of which is lower than a pressure (po) of the gas in the closed cavity (35a, 35b), with the result that, on an optically effective surface (26a) of the optical component, in the region of the at least one closed cavity (35a, 35b) at least one local elevation (41a, 41 b) is formed.2024P00012WQ 11.09.25 SZ00393PCT

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