Method for incorporating temperature-controlled hollow structures into a substrate, in particular into a substrate for an optical element for an EUV projection exposure system, and processing system therefor, method and substrate for producing an optical element, optical element and semiconductor technology system and structured electronic component

Abstract

The invention relates to a method for incorporating temperature-controlled hollow structures (22) into a substrate (12) of a mirror (10) for an EUV projection exposure system, comprising the following steps: (A) providing a substrate (12) consisting of a substrate material 12a; (B) successively focusing a processing light beam (46) onto processing locations (54), where temperature-controlled hollow structures (22) are to be formed, so that the substrate material 12a is removed at the processing locations (54), wherein modified substrate material (58) is formed adjacent the processing locations (54), which has an increased etchability relative to the substrate material 12a; (C) applying a rinsing fluid (82; 82.1) to the processing locations (54), while step (B) is carried out, whereby removed substrate material is rinsed away. In a step (D), an etching medium (80) is applied to the processing locations (54), while step (B) is carried out, wherein the etching medium (80) has an etching effect at the processing locations (54) and removes modified substrate material (58) present there via an etching process. The invention also relates to a processing system (40) for carrying out the method, as well as a method and a substrate (12) for producing an optical element (8), and an optical element (8). The invention further relates to a semiconductor technology system (6) and a structured electronic component (224).

Description

[0001] Method for incorporating hollow tempering structures into a substrate, in particular into a substrate for an optical element for an EUV projection exposure system and processing system therefor, method and substrate for producing an optical element, optical element and system of semiconductor technology and structured electronic component

[0002] REFERENCE

[0003] This application claims priority from German patent application 102023205563.5, filed on June 14, 2023. The complete disclosure of this earlier application is hereby incorporated by reference into the present application.

[0004] BACKGROUND OF THE INVENTION

[0005] 1. Field of the invention The invention relates to a method for incorporating hollow tempering structures into a substrate, in particular into a substrate for an optical element, in particular for a mirror for an EUV projection exposure system, comprising the following steps:

[0006] (A) providing a substrate consisting of a substrate material;

[0007] (B) Successively focusing a processing light beam on processing locations where tempering hollow structures are to be created, so that the substrate material is removed at the processing locations, whereby modified substrate material is created adjacent to the processing locations, which has an increased susceptibility to a chemically active treatment medium relative to the substrate material;

[0008] (C) Applying a flushing fluid to the machining locations while performing step (B), thereby flushing away removed substrate material.Furthermore, the invention relates to a processing system for carrying out this method for incorporating tempering hollow structures into a substrate, in particular into a substrate for an optical element, in particular for a mirror for an EUV projection exposure system, comprising a) a light source with which a processing light beam can be generated; b) a focusing device by means of which the processing light beam can be focused on processing locations at which tempering hollow structures are to be created, so that the substrate material is removed at the processing locations, whereby modified substrate material is created adjacent to the processing locations, which has an increased susceptibility to etching relative to the substrate material; c) a fluid device by means of which the processing locations can be exposed to a rinsing fluid, whereby removed substrate material is rinsed away.

[0009] Furthermore, the invention relates to a method for producing an optical element, in particular for producing a mirror for an EUV projection exposure system.

[0010] Furthermore, the invention relates to a substrate for producing an optical element, in particular for producing a mirror for an EUV projection exposure apparatus, wherein the substrate has tempering hollow structures, as well as an optical element, in particular a mirror for an EUV projection exposure apparatus with a substrate, as well as a semiconductor technology apparatus and a structured electronic component.

[0011] The following description of the invention is based on an optical element in the form of a mirror and its use in an EUV projection exposure system, wherein heat is dissipated from the mirror by flowing a tempering fluid in the form of a cooling fluid through its existing tempering hollow structures.

[0012] In principle, however, the following explanations generally apply to optical elements to which a substrate made of a substrate material can be assigned, into which hollow tempering structures are incorporated, through which a tempering fluid can flow during operation of the optical element for temperature compensation.

[0013] Optical elements are used in semiconductor technology systems, in which an object is irradiated with working radiation using one or more optical elements. In addition to EUV projection exposure systems, such semiconductor technology systems include mask inspection systems and wafer inspection systems.

[0014] On the one hand, tempering can involve cooling or heating the optical element, or at least a portion of it. This means that the optical element, as a whole or at least in a volume region, is brought to a temperature it did not previously have with the aid of the tempering fluid.

[0015] On the other hand, tempering can also lead to a certain temperature or a certain temperature range of the optical element or at least a region of the optical element being maintained or remaining so.

[0016] These considerations also generally apply to components with a corresponding substrate that supports or can support one or more functional units and into which hollow temperature control structures are incorporated, through which a temperature control fluid can flow during operation of the component. Such a component can, for example, provide a sensor device; in this case, the substrate supports sensor units as functional units.

[0017] 2. Description of the state of the art

[0018] Microlithographic projection exposure systems are used in chip manufacturing to transfer patterns on a mask onto a photoresist previously applied to a wafer. To do this, the mask is illuminated with light and imaged onto the light-sensitive layer in a reduced size. In EUV projection exposure systems, the light has a wavelength between approximately 5 nm and approximately 30 nm; commercially available systems use light with a wavelength of 13.5 nm.

[0019] However, there are no optical materials with sufficiently high transmittance for such short wavelengths. Therefore, in EUV projection exposure systems, the lenses typically used for longer wavelengths are replaced by mirrors, and the mask also contains a pattern of reflective structures.

[0020] Providing mirrors for EUV projection exposure systems is technologically challenging. The substrate consists of a substrate material, which is usually glass, e.g., quartz glass, titanium-doped quartz glass such as ULE®, or a glass ceramic. Suitable glass ceramics are offered under the trade names Clearceram® or Zerodur® and have the property of having a very low coefficient of thermal expansion at the operating temperature of the mirror 10.

[0021] A coating is applied to the substrate that reflects the EUV light and consists of a multitude of thin double layers with varying refractive indices.

[0022] Even with such complex coatings, the mirrors' reflectivity for EUV light rarely exceeds 70%, and even then only for light that hits the reflective coating perpendicularly or at angles of incidence of a few degrees. The portion of the EUV light not reflected by the coating is absorbed in the substrate, where it leads to significant heating, as the EUV light sources used are very powerful. Even when glass-ceramics with low thermal expansion coefficients are used, the heating can lead to intolerable deformation of the mirrors.

[0023] It was therefore proposed to provide the substrates with hollow tempering structures, which in this case are hollow cooling structures, whereby, in particular, tempering channels are provided in the form of cooling channels through which water or another tempering fluid, i.e., here a cooling fluid, flows during operation and thus dissipates heat. Such tempering channels can have small cross-sectional diameters in the order of approximately 1 mm. 2 and ideally run just below the reflective coating.

[0024] An overview of the methods known to date for creating temperature control channels is contained in the applicant's application DE 10 2021 214 310.5, the disclosure of which is hereby incorporated. Particularly promising are methods in which a processing light beam is successively focused on processing locations where temperature control channels are to be created.

[0025] In particular, the method of the type mentioned above has become established. In this method, the substrate material is abraded by the processing light beam using a processing system of the type mentioned above, and the abraded substrate material is flushed away by a rinsing fluid. A temperature control channel is machined into the substrate material, starting from the surface of the substrate, so that a temperature control channel section is successively formed that lengthens over the course of the process until the desired temperature control channel is completely machined. Typically, the externally accessible temperature control channel section is used as a connection to and from the processing locations.

[0026] In this process, modified substrate material is created adjacent to the processing locations, which is more susceptible to etching than unprocessed substrate material. This modified substrate material is created primarily by absorption of the high-energy processing light beam and by thermal diffusion of ablated substrate material from the processing locations. In the case of a laser, experts refer to an area with modified substrate material as a so-called laser-affected zone, or LAZ for short. The modified substrate material can also differ from the substrate material in terms of, among other things, density, thermal expansion coefficient, and existing material stresses. However, such a material-inhomogeneous substrate is not suitable for use in an EUV projection exposure system.Therefore, the modified substrate material must be removed; in the known process, the modified substrate material is etched away in a subsequent second step using an etchant such as, in particular, hydrofluoric acid HF or potassium hydroxide KOH.

[0027] The overall process speed for forming the desired hollow tempering structure is already limited by the fact that a two-stage process must be carried out. In particular, the achievable etching rate in the second process stage has a significant influence on the process speed. With longer hollow tempering structures or channels, the intact substrate material surrounding the hollow structures may be undesirably attacked by the etchant, resulting in structures that are conical in the direction of flow or irregular cross-sections. To achieve a sufficient material removal rate, the etchant must also be heated frequently; for example, 10 M KOH is used at temperatures of approximately 90°C. This, in turn, poses a risk when handling the etchant.

[0028] In addition, fluctuations in the material structure of the substrate material, for example due to areas with different refractive indices / different transmission or due to the formation of thermal lenses, can lead to fluctuations in the material removal, which in turn can lead to undesirable deviations in the cross-sectional profile of the tempering cavity structures and roughness on their lateral surfaces.

[0029] SUMMARY OF THE INVENTION

[0030] It is an object of the invention to provide a method and a processing system, a substrate, an optical element and a semiconductor technology system of the type mentioned at the outset, which take these ideas into account and by means of which, in particular, tempering hollow structures can be introduced into the substrate with high precision and quality as well as good process speed, so that, using such an optical element, among other things, structured electronic components with significantly small structures can be produced, and to provide such components.

[0031] This object is achieved in a method of the type mentioned at the outset in that, in a step (D), the processing locations are exposed to a treatment medium, while step (B) is carried out, wherein the treatment medium exerts an effect at the processing locations and removes modified substrate material present there.

[0032] When referring to processing locations in the plural, this is always intended to clarify the temporal progression of the machining of the tempering hollow structures. In fact, at any given time, there is always only one processing location at the focal point of the processing light beam.

[0033] According to the invention, it was recognized that it is possible to remove the resulting modified substrate material at the moment of its formation and to carry out the treatment, and thus the attack against the modified substrate material, which is more susceptible to the chemically active treatment medium, at the processing locations. In this way, the desired tempering cavity structure is formed in a single process step.

[0034] The advantages of the features explained below become particularly clear from the description.

[0035] The chemically active treatment medium may be an etching medium, an oxidizing agent or a reducing agent and is preferably an etching medium by which the modified substrate material (58) is removed by an etching process in step (D).

[0036] If the chemically active treatment medium is an etching medium, this can be advantageously adapted to its handling, for example, by a) the etching medium as such being an etchant; or b) the etching medium being an etchant precursor from which an etchant can be formed at the processing sites, and in particular being a temperature-activatable precursor or a reaction-activatable precursor or a photoactivatable precursor.

[0037] A precursor is generally less aggressive and less risky to use than an etchant. A temperature-activated precursor becomes an etchant above a threshold temperature. A reaction-activated precursor becomes an etchant through a reaction with a reactant. A photoactivatable precursor becomes an etchant through irradiation with activation radiation. This activation can be achieved by the processing light beam.

[0038] Preferably, the etching medium is a) an etchant in the form of hydrofluoric acid HF or potassium hydroxide KOH; or b) an etchant precursor in the form of potassium hydrogen fluoride HKF2, ammonium hexafluorosilicate (NH4ZtSiFe), calcium fluoride CaF2, sodium fluoride NaF, potassium fluoride KF, lithium fluoride LiF, ammonium hydrogen difluoride NH4HF2.

[0039] Preferably, the chemically active treatment medium, in particular the etching medium, is provided by the rinsing fluid. In this case, the physical rinsing by the fluid flow is combined with the chemical treatment, in particular the etching, by the chemically active treatment medium carried by the rinsing fluid.

[0040] If the chemically active treatment medium is the etching medium, the alternatives that can be advantageously used are that a) the rinsing fluid provides the etching medium as an etchant or as a temperature-activatable etchant precursor from which an etchant is formed above a threshold temperature, or as a photoactivatable precursor from which an etchant is formed by irradiation with activating radiation; or b) the rinsing fluid is a first rinsing fluid that provides a reaction-activatable etchant precursor from which etchant can be formed at the processing locations by a reaction with a reactant, and the reactant is provided by a second rinsing fluid.

[0041] It may be beneficial if the machining locations are also exposed to an inert rinsing fluid.

[0042] A mixture of fluids, media, and materials flows away from the processing sites as a collection fluid, which may also carry unreacted etching agents. This can attack and negatively alter the material in the already formed section of the desired tempering cavity structures. Therefore, it is advantageous to extract the collection fluid flowing away from the processing sites using a suction device.

[0043] Alternatively or additionally, the collection fluid flowing away from the processing locations can be diluted and / or neutralized with the aid of an auxiliary medium.

[0044] The above-mentioned object is achieved in a processing system of the type mentioned above in that d) the fluid device is configured such that the processing locations are exposed to a treatment medium while the focusing device is in operation and the processing light beam is focused on the processing locations, wherein the treatment medium exerts an effect at the processing locations and removes any modified substrate material present there. Accordingly, it is advantageous if the chemically active treatment medium is an etching medium, an oxidizing agent, or a reducing agent, with an etching medium being preferred, by which the modified substrate material is removed through an etching process.

[0045] It is particularly advantageous if the treatment medium is an etching medium and a) the etching medium as such is an etchant; or b) the etching medium is an etchant precursor from which an etchant can be formed at the processing sites, and in particular is a temperature-activatable precursor or a reaction-activatable precursor or a photoactivatable precursor.

[0046] Here too, the etching medium is preferably a) an etchant in the form of hydrofluoric acid HF or potassium hydroxide KOH; or b) an etchant precursor in the form of potassium hydrogen fluoride HKF2, ammonium hexafluorosilicate (NH4SiFe), calcium fluoride CaF2, sodium fluoride NaF, potassium fluoride KF, lithium fluoride LiF, ammonium hydrogen difluoride NH4HF2.

[0047] Structurally, it is advantageous if the fluid device comprises a conveyor line with a supply line that has a discharge end and is connected to a reservoir in which a flushing fluid is stored, which provides the treatment medium. The supply line is preferably routed through the already formed section of the hollow tempering structure to the treatment sites, which will be explained again below.

[0048] In this context, a reservoir is understood to be any source that provides a material or mixture of materials.It may be advantageous for the chemically active treatment medium to be the etching medium and for a) the rinsing fluid to provide the etching medium as an etchant or as a temperature-activatable etchant precursor from which an etchant is produced above a threshold temperature, or as a photoactivatable etchant precursor from which an etchant is produced by irradiation with activating radiation; or b) the conveyor line is a first conveyor line and the rinsing fluid defines a first rinsing fluid which provides a reaction-activatable etchant precursor from which etchant can be produced at the processing locations by a reaction with a reactant, and for there to be a second conveyor line with a second supply line having a discharge end and being connected to a second reservoir in which a second rinsing fluid is held which provides the reactant.

[0049] The fluid device may comprise an inert conveying line with a supply line having a discharge end and connected to a reservoir in which an inert flushing fluid is stored.

[0050] In order to ensure that the delivered fluids reach the processing locations in the desired manner, it is advantageous for each existing conveyor line to comprise a line conveyor by means of which the respective delivery end of the supply line can be guided to the processing locations.

[0051] With regard to the suction of collected fluid explained above, the fluid device preferably comprises a suction device with a suction line having a suction end and connected to a suction pump, by means of which collected fluid flowing away from the processing locations can be suctioned away. It is advantageous if the suction device comprises a line conveyor, by means of which the suction end of the suction line can be guided to the processing locations, in particular at a greater distance from the processing locations than the discharge end(s) of one or more supply lines.

[0052] The fluid device may comprise an auxiliary medium conveying line with a supply line having a discharge end and connected to a reservoir in which an auxiliary medium is stored, in particular an inert rinsing fluid or a neutralizing medium which can neutralize the treatment medium.

[0053] The auxiliary medium conveying line also preferably comprises a line conveyor, by means of which the discharge end of the supply line can be guided to the processing locations, in particular at a greater distance from the processing locations than the discharge end(s) of one or more supply lines of the other conveying lines.

[0054] In the method mentioned at the outset for producing an optical element, in particular for producing a mirror for an EUV projection exposure apparatus, hollow tempering structures are incorporated into a substrate according to the method explained above and further processing comprises one or more steps of chemical and / or physical processing of at least one surface of the substrate and the production or application of a coating to the substrate which is at least designed to reflect at least 50% of EUV light incident perpendicularly or almost perpendicularly.

[0055] In a substrate of the type mentioned at the outset, the above-mentioned object is achieved in that at least one tempering hollow structure defines an inner surface which, at least in some regions, has a mean roughness Ra according to DIN EN ISO 25178, as of April 2023, between 10.0 pm and 5.0 pm, which in particular lies between 10.0 pm and 6.5 pm, between 10.0 pm and 8.0 pm, between 8.5 pm and 5.0 pm, between 7.0 pm and 5.0 pm or between 8.5 pm and 6.5 pm, or which, at least in some regions, has a mean roughness Ra of 5.0 pm and less, which in particular lies between 5.0 pm and 0.1 pm, preferably between 4.5 pm and 0.125 pm, between 4.0 pm and 0.15 pm, between 3.5 pm and 0.175 pm or between 3.0 pm and 0.2 pm lies.

[0056] The above-mentioned object is also achieved by a substrate of the type mentioned at the outset, in which at least one tempering hollow structure defines an inner surface having a surface topography whose geometric shape results from a superposition of countersink structures extending into a substrate material of the substrate.

[0057] Preferably, one or more countersunk structures are segments of bodies that are point-symmetric or at least axisymmetric.

[0058] The surface topography advantageously defines adjacent depression areas between which peripheral areas, particularly linear peripheral areas, run.

[0059] One or more countersink areas may be axisymmetric or non-axisymmetric.

[0060] It is advantageous if an axisymmetric countersunk area follows a section of the outer surface of a spherical segment, an ellipsoidal segment or a paraboloid.

[0061] Advantageously, a tempering hollow structure is a tempering channel that has one or more of the following features: a) the tempering channel has a diameter between 0.5 mm and 20 mm, preferably between 1 mm and 5 mm; b) the tempering channel has a length of at least 10 cm, at least 15 cm, or at least 20 cm. c) the tempering channel is curved or has at least one curved section; d) the tempering channel has a section that follows the curvature of a support surface for a coating of the substrate; e) the tempering channel has a strongly curved section that has an angle of curvature between 60° and 120°, in particular between 80° and 100°, preferably of approximately 90°; f) the tempering channel has a strongly curved section which has a curvature angle between 60° and 120°, in particular between 80° and 100°, preferably of approximately 90° and follows an arc;g) the temperature control channel has a strongly curved section which has an angle of curvature between 60° and 120°, in particular between 80° and 100°, preferably of approximately 90°, and follows an arc and defines an outer radius of curvature R and a diameter D, wherein a ratio R / D of the radius of curvature R to the diameter D is between 2 and 6, preferably between 2.5 and 5, and particularly preferably between 2.5 and 3.5; h) the temperature control channel runs at a distance of 1.0 mm to 50.0 mm, from 1.0 mm to 20.0 mm, from 1.0 mm to 10.0 mm, or from 1.0 mm to 5.0 mm, relative to a support surface for a coating of the substrate;

[0062] A reliable guarantee of good flow properties is also achieved according to the invention in a substrate of the type mentioned at the outset, which defines a carrier surface for a coating, in that the fit of the carrier surface changes by less than 100 pm, in particular by less than 50 pm and further in particular by less than 25 pm over a service life of the substrate of up to 10 years, at least up to five years and at least up to two years.

[0063] Some or all of the features explained above can also be realized in combinations in a substrate to achieve synergistic advantages.

[0064] Preferably, hollow tempering structures are incorporated into the substrate according to the method explained above. In an optical element of the type mentioned above, the above-mentioned object is achieved by a substrate having some or all of the features described above.

[0065] The pass of the optical element advantageously changes by less than 100 pm, in particular by less than 50 pm and further in particular by less than 25 pm over a lifetime of the optical element of up to 10 years, at least up to five years and at least up to two years.

[0066] These properties are particularly advantageous in a mirror for an EUV projection exposure system, wherein the substrate has a carrier surface carrying a coating that is at least designed to reflect at least 50% of EUV light incident vertically or nearly vertically.

[0067] The above-mentioned properties of the optical element are advantageously combined.

[0068] In a semiconductor technology system, the task is solved by such an optical element,

[0069] This is particularly advantageous in an EUV projection exposure system.

[0070] In the case of a structured electronic component, the above-mentioned task is solved by manufacturing it using such a semiconductor technology system.

[0071] BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In the following, exemplary embodiments of the invention are explained in more detail with reference to the drawings. In these drawings:

[0073] Figure 1 schematically shows a section of an optical element in the form of a mirror for an EUV projection exposure system, which has cooling hollow structures in the form of cooling channels through which a cooling fluid flows by means of a cooling system;

[0074] Figure 2 shows a processing system with which tempering hollow structures are machined into a substrate by means of a processing light beam;

[0075] Figure 3 shows a part of the processing system according to Figure 2, wherein the substrate according to section B in Figure 2 is shown on a larger scale and with a result achieved by known methods;

[0076] Figures 4 to 9 each show a part corresponding to Figure 3 in processing systems according to the invention according to one of six embodiments;

[0077] Figure 10 shows a substrate for an EUV mirror into which tempering hollow structures have been incorporated;

[0078] Figure 11 A shows a topography image of a surface area of ​​a tempering cavity structure;

[0079] Figure 11 B shows a section to illustrate an achieved mean roughness value Ra;

[0080] Figure 12 shows schematically a longitudinal section of a tempering hollow structure;

[0081] Figure 13 shows section XIII in Figure 10 on an enlarged scale;

[0082] Figure 14A shows a passe-image of a substrate with intermediate structures before an etching process;

[0083] Figure 14B is a passe-image of this substrate with preserved tempering hollow structures after an etching process;

[0084] Figure 14C shows a differential view of the images according to Figures 14A and 14B; Figure 15 shows a schematic diagram of a semiconductor technology system using the example of an EUV projection exposure system.

[0085] DESCRIPTION OF PREFERRED EMBODIMENTS

[0086] 1. Structure of an optical element using the example of an EUV mirror

[0087] Figure 1 shows a semiconductor technology system described above, generally designated 6, and a section of an optical element designated 8 overall, which is illustrated by way of example as a mirror 10 for an EUV projection exposure system. Mirror 10 can be arranged in the illumination system or in the projection lens.

[0088] The optical element 8, and thus the mirror 10, comprises a substrate 12 made of a substrate material 12a, which in the present embodiment of the mirror 10 is therefore a mirror substrate. In practice, such a mirror substrate is, in particular, a glass ceramic.

[0089] In the present embodiment, the substrate 12 is monolithic, which is also the preferred embodiment. In modifications not specifically shown, the substrate 12 can also be assembled from sub-segments. Additive manufacturing methods are generally suitable in this case. For example, 3D printing processes are also possible, as are laser welding processes or techniques for thermally bonding workpieces.

[0090] In the case of mirror 10, the substrate 12 has a precisely machined surface 14, the curvature of which determines the optical properties of the mirror 10. The surface 14 of the substrate 12 serves as the support surface and will be referred to as such below. The support surface 14 carries a coating 16, which provides the optical properties of the optical element 8. In the mirror 10 shown here, the coating 16 is designed to predominantly reflect incident EUV light 18. As illustrated in the enlarged section A, this coating 16 is multi-layered in the present embodiment and, in particular, is constructed from several double layers 20 that have been applied to the support surface 14. The coating 16 has a reflection coefficient of at least 50%, preferably more than 70%, for perpendicularly incident EUV light 18. The degree of reflection achieved during operation depends on the angle of incidence of the EUV light 18.

[0091] In addition to the double layers 20, the coating 16 can also comprise further layers that do not contribute to reflection, but possibly to stabilization and / or protection of the coating 16 or the optical element 8 or the mirror 10. For example, this can provide protection against components of a hydrogen plasma. Such further layers can be provided between the double layers 20 in the interior of the coating 16, between the double layers 20 and the carrier surface 14, and / or on the side of the double layers 20 remote from the carrier surface 14.

[0092] In an optical element 8, the coating 16 can also be formed by modifying the outer surface of the substrate 12 through processing and / or treatment. In this case, the coating 16 is not a specially applied coating, but rather defines a layer of the substrate 12 as such; the underlying surface, as a transition to the substrate material 12a, is then the support surface 14.

[0093] In the mirror 10 explained here and the application of EUV light 18, the non-reflected portion enters the substrate 12 and is absorbed there, predominantly in the vicinity of the support surface 14. As a result of this absorption, the substrate 12 heats up, particularly in the vicinity of the areas of the support surface 14 exposed to the EUV light 18. Since the thermal expansion coefficient of the substrate material 12a is not identical to zero and is also temperature-dependent, the heating can lead to changes in the shape of the substrate 12, which affect the optical properties of the mirror 10. With regard to optical elements 8, generally speaking, temperature changes in the substrate 12 can affect the optical properties of the optical element 8.

[0094] However, due to the extremely tight specifications in EUV projection exposure systems, changes in the optical properties of the mirrors are not tolerable, or at best, only negligible. However, in general, the optical properties of optical elements 8 should remain stable, and the functionality of components should be maintained.

[0095] In order to minimize temperature fluctuations in the substrate material 12a and the associated changes in shape of the substrate 12, several tempering hollow structures 22 are incorporated into the substrate 12.

[0096] During operation of the EUV projection exposure system, these hollow tempering structures 22 are flowed through by a tempering fluid in the form of a cooling fluid 24, whereby cooling water is used in practice; however, other cooling liquids and cooling media are also possible.

[0097] The cooling fluid 24 absorbs the heat introduced by the EUV light 18 and removes it from the substrate 12. For this purpose, the temperature control hollow structures 22 are connected to a cooling unit 26 and a pump unit 28 of a cooling system designated overall by 30. The pump unit 28 draws the cooling fluid 24 from the temperature control hollow structures 22 and feeds it via a return line 32 to the cooling unit 26. There, the cooling fluid 24 is cooled to its target temperature before flowing through the temperature control hollow structures 22 again. This circuit is illustrated in Figure 1 by corresponding arrows.

[0098] Typically, the hollow temperature control structures 22 run close to the support surface 14 and at least partially parallel thereto. In the exemplary embodiments described here, the hollow temperature control structures 22 are designed as temperature control channels 34, of which three temperature control channels 34.1, 34.2 and 34.3 are illustrated. The temperature control channels 34 each extend between two openings 36, which are only designated in Figure 1 for the temperature control channel 34.1, wherein each temperature control channel 34 is connected via its openings 36 to the cooling unit 26 and to the pump unit 28. The openings 36 thus define, depending on the assignment, an inlet or an outlet of the temperature control channels 34 for the cooling fluid 24. The cross-section of the temperature control channels 34 does not have to be constant and can be, for example, circular, oval, rectangular or even annular. The tempering hollow structures 22 can have changing cross-sections and shapes depending on the position in the substrate 12.In the present embodiments, the openings 36 of the temperature control channels 34 are arranged on the rear side 38 of the substrate 12 opposite the carrier surface 14.

[0099] In modifications not specifically shown, the temperature control hollow structures 22 may also be more extensive chambers in which the cooling fluid 24 is exchanged only slowly and in which no longitudinal axis is defined, as is characteristic of a channel.

[0100] The arrangement of the temperature control channels 34 shown in the figures is only exemplary and may vary in actual systems; the number of temperature control channels 34 may also be larger or smaller. For example, the openings 36 may also be arranged on the lateral flanks of the substrate 12, or at least one temperature control channel 34 may be provided that runs through the substrate 12 or a portion thereof in a meandering or spiral manner.

[0101] In a further modification, one or more temperature control channels 34 can also extend from a distribution line or a distribution chamber in the substrate 12. Such temperature control channels 34 then open with their openings 36 at one or both ends into such a distribution line or distribution chamber, from which the temperature control channels 34 are then supplied with the temperature control fluid. The distribution line or distribution chamber and, if applicable, the end of a temperature control channel 34 remote therefrom are then connected accordingly to the cooling system 30.

[0102] During the production of an optical element 8 using the method described here for producing tempering hollow structures 22, various stages of the substrate 12 are defined.

[0103] A first stage of the substrate 12 defines a type of raw substrate 12', which is still largely unprocessed and untreated and in which no structural support surface 14 is yet formed. In the case of the substrate 12 explained above, which is a mirror substrate, such a raw substrate is, for example, a glass cuboid made of glass ceramic.

[0104] A second stage of the substrate 12 defines a carrier substrate 12", in which the carrier surface 14 is created and formed. This may require a variety of chemical and / or physical steps, which may include processes such as grinding, turning, polishing, and / or etching.

[0105] A third stage of the substrate 12 then defines an element substrate 12'", in which the support surface 14 is provided with at least the coating 16 that determines the optical properties. If the resulting optical element is a mirror, the element substrate 12'" is terminologically a mirror substrate. Accordingly, the substrate 12 in Figure 1 also bears the reference symbol 12'", since it is shown there in the element substrate stage. If the substrate 12 is, for example, part of a sensor device, as described above, the element substrate 12'" is terminologically a sensor substrate.

[0106] The creation of the tempering hollow structures 22 in the substrate 12, described below, can in principle be carried out at any stage of the substrate 12. This usually occurs at the stage of the raw substrate 12', but can also be carried out, for example, at the stage of the carrier substrate 12" or even at the stage of the element substrate 12'".

[0107] In the present case, the production of the tempering hollow structures 22 is explained in particular using the example of the carrier substrate 12" in order to illustrate the function of the mirror 10 obtained later, as envisaged in the present embodiment.

[0108] 2. Creating the tempering hollow structures using the example of the tempering channels

[0109] Figure 2 illustrates the substrate 12 with a dashed outer contour line as a raw substrate 12' and with solid lines as a carrier substrate 12", ie as a substrate 12 with an already formed carrier surface 14 before the reflective coating 16 is applied.

[0110] In the following, only the substrate 12 is shown in the enlarged sections. The outer contour of the raw substrate 12' is only partially indicated at the edge in Figure 10. The shape of the future support surface 14 is also already defined in the raw substrate 12', and this imaginary support surface 14 serves as a reference surface for defining the shape of the hollow tempering structures 22 in the substrate 12.

[0111] Figure 2 shows a processing system, designated overall by 40, with which the tempering hollow structures 22 are machined into the substrate 12. The provision of such a substrate 12 defines the process step (A) mentioned above.

[0112] In this case, the removal of substrate material 12a begins at the location of one of the openings 36. This is illustrated by the example of the temperature control channel 34.1, of which a section of a temperature control hollow structure 22 is already incorporated into the substrate 12, and here specifically a temperature control channel section 42 is present, which extends into the substrate 12 from the opening 36 that forms the outlet to the pump unit 28 in the configuration shown in Figure 1. In the following, reference is made to the temperature control channel 34.1 in all exemplary embodiments as representative of the other temperature control channels 34 and generally for any type and arrangement of temperature control hollow structures 22.

[0113] The processing system 40 includes a light source 44 that generates a processing light beam 46. The light source 44 is preferably a high-power laser that generates ultrashort pulses. These can be pulses in the femtosecond, picosecond, or nanosecond range. In this case, the processing system 40 implements a laser ablation system.

[0114] The processing light beam 46 can be directed at various locations on the substrate 12 with the aid of a scanning device 48 and a focusing lens 50, which together form a focusing device. The relative arrangement between the substrate 12 and the processing system 40 can also be changed with the aid of a moving table (not shown) such that the processing light beam 46 can be directed at any location on the substrate 12 after passing through the focusing lens 50. The scanning device 48, the focusing lens 50, and any moving table present are controlled by a control device 52 such that the processing light beam 46 is successively focused on all processing locations 54 on the substrate 12 where temperature control channels 34 are to be created. Alternatively, the relative arrangement between the substrate 12 and the processing system 40 can be changed by moving the processing system 40.For small substrates 12, travel operations can be dispensed with provided that the scanning device 48 covers a sufficiently large area.

[0115] At the focal points generated by the focusing lens 50, the intensity of the processing light beam 46 is so high that the material of the substrate 12 is removed. The area in which the processing light beam 46 removes material defines a respective processing location 54, which naturally moves with the focal point of the processing light beam 46. The locations of the focal points and thus the processing locations 54 determine where a temperature control channel 34 is created in the substrate 12. To generate a temperature control channel 34 with a sufficiently large cross-section, the processing light beam 46 traverses the entire cross-section in a radial direction according to a predetermined pattern at a specific axial position. This process is then repeated at adjacent axial positions until the temperature control channel 34 has the desired axial dimension.This creates modified substrate material 56 adjacent to the processing locations 54, which, in particular, has an increased susceptibility to a chemically active treatment medium compared to the substrate material 12a of the substrate 12. This is illustrated in Figure 3, which shows, on an enlarged scale, the section of the substrate 12 delimited by a dashed line in Figure 2 and designated B.

[0116] The formation and properties of the modified substrate material 56 were explained at the beginning. If this modified substrate material 56 is initially formed at a location that will later be struck by the processing light beam 46 as the processing location 54, the modified substrate material 56 there will then be removed accordingly.

[0117] In summary, the method step (B) mentioned at the outset is defined, in which the processing light beam 46 is successively focused on processing locations at which tempering hollow structures 22 are to be created, so that the substrate material 12a is removed at the processing locations 54, whereby modified substrate material 56 is created adjacent to the processing locations 54, which has an increased susceptibility to etching relative to the substrate material 12a.

[0118] There is now also a fluid device, designated overall by 58, which is also controlled by the control device 52. The fluid device 58 defines a conveyor line 60 and applies a flushing fluid to the processing locations 54 while the substrate material 12a of the substrate 12 is removed, whereby the removed substrate material is flushed away by the flushing fluid. This defines the method step (C) mentioned above.

[0119] In this case, removed substrate material is understood to mean any material or material mixture that was created at the processing location 54 from the substrate material 12a of the substrate 12, regardless of its structure or state of aggregation. Figure 3 additionally shows the other components of the fluid device 58 with the conveyor line 60, as implemented in a known method, as well as the result achieved thereby. In this known method, the processing locations 54 are exposed to an inert flushing fluid 62, which flushes away the substrate material removed at the processing location 54 but has no reactive properties. The inert flushing fluid 62 is generally demineralized water.

[0120] The conveyor line 60 comprises a flexible supply line 64 with a discharge end 66, via which the inert rinsing fluid 62 is supplied to the processing locations 54 in order to receive the removed substrate material there and to discharge it via the already formed channel.

[0121] The discharge end 66 of the supply line 64 is brought into a discharge position which is adjacent to the processing location 54 in such a way that the discharged fluid reaches the processing location 54 at least partially.

[0122] The conveyor line 60 also includes a reservoir 68 with a feed pump 70, from which the supply line 64 is fed with the inert flushing fluid 62. In addition, the conveyor line 60 includes a line conveyor 72, with the aid of which the discharge end 66 of the supply line 64 can be guided to the processing location(s) 54 and can always maintain a suitable discharge position; the corresponding control is carried out by the control device 52. In Figure 3, the line conveyor 72 is illustrated by way of example as a winding roll 74 for winding or unwinding the supply line 64. In the subsequent figures, the line conveyor 72 is shown only schematically.

[0123] However, during the material removal, no channel section 42 is formed, and after the material removal has been completed, no tempering channel 34.1 is formed, as is the case with the method according to the invention, which will be explained again below. Rather, only a precursor hollow structure 76 is created, which is delimited by a shell 78 made of the modified substrate material 56. Figure 3 accordingly shows only a section of such a precursor hollow structure 76 during the production process.

[0124] Only when the jacket 78 is removed from the modified substrate material 56 is the desired temperature control hollow structure 22 or, more specifically, the desired temperature control channel 34.1 provided.

[0125] For this purpose, in the known methods, subsequent processing steps, such as etching or tempering, are carried out, ie with the processing light beam 46 deactivated after the removal of the substrate material 12as of the substrate 12, by means of which the jacket 78 is removed.

[0126] In contrast to this, according to the invention, in a step (D) the processing locations 54 are exposed to a chemically active treatment medium 80, while the substrate material 12a at the processing locations 54 is removed during the implementation of method step (B), wherein the chemically active treatment medium 80 exerts an effect against modified substrate material 58 present at the processing locations 54 and removes this.

[0127] Thus, on the one hand, substrate material removed by the rinsing fluid is flushed away from the processing locations 54, and on the other hand, the modified substrate material 56 is removed by the chemically active treatment medium 80, whereby the modified substrate material 56 separated as particles but not yet dissolved is also flushed away. Overall, the material removal thus increases by the proportion of the modified substrate material 56 that is removed by the chemically active treatment medium 80.

[0128] At the same time, the chemically active treatment medium 80 also acts on substrate material removed by the processing light beam 46, whereby the size of the removed particles is reduced, which counteracts clogging of the tempering channel section 42, which serves as an outflow channel.

[0129] In the present embodiment, the chemically active treatment medium 80 is an etching medium 80', and the modified substrate material 56 is removed by an etching process. Alternatively, the treatment medium 80 may also be an oxidizing agent or a reducing agent, which also includes the treatment medium 80 containing an oxidizing agent or a reducing agent.

[0130] The etching medium 80' can either be an etchant with this etching effect as such, or the etching medium 80' can be an etchant precursor from which an etchant with this etching effect can be formed at the processing locations 54, whereby this etchant precursor indirectly exerts an etching effect. The substance or compound that defines an etchant or an etchant precursor does not have to be present in the etching medium 80' at a concentration of 100%, but only has to be encompassed by the etching medium 80'.

[0131] On the one hand, temperature-activatable precursors can be used as the etchant precursor, from which an etchant is formed above a threshold temperature. This then occurs through the application of heat due to the temperatures prevailing at the processing locations 54. Alternatively, reaction-activatable precursors can be used, from which the etchant is formed by a reaction with a reactant at the processing locations 54. When using such reaction-activatable precursors, the processing locations 54 are exposed to such a reactant, so that the etchant is formed from the precursor at the processing locations. Furthermore, photoactivatable precursors can be used, from which the etchant is formed by irradiation with activation radiation.

[0132] Bases and acids can be used as etching agents. Bases are particularly strong bases, such as potassium hydroxide KOH. Strong acids can also be used, with hydrofluoric acid HF being particularly used for acids, which is a weak but highly reactive acid. Alternatively, an ammonium fluoride buffer NH4F / H2O / HF or CF4 for dry etching can be used. Potassium hydrogen difluoride HKF2, for example, can be used as a temperature-activated etchant precursor for the formation of hydrofluoric acid HF as an etchant at the processing locations 54. This can be used at temperatures above approximately 239°C according to

[0133] HKF2-> HF + KF reacts.

[0134] As a temperature-activated etchant precursor for the formation of hydrofluoric acid HF as etchant at the processing locations 54, ammonium hexafluorosilicate ((NH4)2[SiFe]) can also be used, which at temperatures above about 100°C according to

[0135] ((NH4)2[SiF6]) - 2HF + SiF6 + 2NH3 reacts.

[0136] The temperature required for the formation of the etchant from the etchant precursor is achieved at the processing locations 54 by the processing light beam 46, with which the respective temperature-activated etchant precursor interacts at the processing locations 54.

[0137] Reaction-activatable etchant precursors may include, for example, calcium fluoride CaF2, sodium fluoride NaF, potassium fluoride KF, lithium fluoride LiF, ammonium hydrogen difluoride NH4HF2, or the like, which react with reactants in the form of proton donors such as sulfuric acid H2SO4, hydrochloric acid HCl, or phosphoric acid H3PO4 in the desired manner.

[0138] Embodiments of the processing system 40 and the method according to the invention will now be explained with reference to Figures 4 to 8. For all fluid devices 58 described below, it is assumed that the installed components are resistant to the fluids and media used and can convey these without impairment or be flowed through by them. In principle, the fluid device 58 is configured such that the processing locations 54 can be exposed to the etching medium 80' while the focusing device 48, 50 explained above is in operation and the processing light beam 46 is focused on the processing locations 54.

[0139] Figure 4 illustrates a first embodiment of the processing system 40 and the method according to the invention and the result achieved thereby; the fluid device 58 described with reference to Figure 3 is used with the same components 60 to 74, which, however, are suitable for conveying the etching medium 80'.

[0140] Here, the above-explained steps (C) and (D) are combined in that the etching medium 80' is provided by a rinsing fluid 82 comprising the etching medium 80'. The reservoir 68 is thus filled with this rinsing fluid 82. In this configuration of the fluid device 58, only an etchant, a temperature-activatable precursor, or a photoactivatable precursor are considered as the etching medium 80'. Hereinafter, an etchant is designated by 80a, a temperature-activatable precursor and a photoactivatable precursor by 80b, and a reaction-activatable precursor by 80c.

[0141] If the etching medium 80' is an etchant 80a as such, the rinsing fluid 82 forms a dilute acid or base.

[0142] A collection fluid, designated 84 overall, flows away from the processing locations 54. The collection fluid 84 is a mixture of all fluids, media, and materials flowing away from the processing locations 54. Accordingly, the collection fluid 84 may also carry etching agent 80a with it. The flow of the collection fluid 84 is indicated by corresponding arrows. The collection fluid 84 flows through the already formed temperature control channel section 42 to its opening 36 and there out of the substrate 12.

[0143] It can be exploited that the etching medium 80' is locally heated at the processing locations 54 by the processing light beam 46. This allows the etching effect of the etchant 80as acting at the processing locations 54 to be further intensified without having to supply already hot etchant 80a to the processing locations 54. The concentration of the etching medium 80' in the rinsing fluid 82 or the concentration of the etchant 80as ultimately reaching the processing locations 54 or being formed there can therefore be kept as low as possible and adjusted so that the required etching effect for removing the modified substrate material 56 is achieved at the temperature achieved at the processing locations.

[0144] In general, the method according to the invention can produce very uniform tempering channels 34 and generally very uniform tempering hollow structures 22.

[0145] This is supported by the fact that significant material removal occurs only locally at the processing locations 54, where the etching agent 80a present has the required temperature. In the already processed areas through which the collecting fluid 84 flows, there is no or only minimal material removal by the etching agent 80a due to the lower temperature of the collecting fluid 84 when it is carried along by the collecting fluid 84.

[0146] Figure 5 shows a second embodiment of the processing system 40 and the method, in which the fluid device 58 additionally comprises a suction device 86 having a suction line 88 with a suction end 90, a line conveyor 92, and a suction pump 94. The suction device 86 suctions at least a large portion of the collection fluid 84 flowing from the processing locations 54 and conveys it to a schematically indicated collection container 96.

[0147] The suction line 88 extends alongside the supply line 64 through the already formed tempering channel section 42 to a suction position where the suction end 90 is located. The suction end 90 is guided with the aid of the associated line conveyor 92. The suction position of the suction line 88 is always farther away from the processing locations 54 than the discharge position of the supply line 64. In other words, the suction end 90 of the suction line 88 is always located farther in front of the processing locations 54 than the discharge end 66 of the supply line 64.

[0148] This measure ensures even more reliable targeting of the etchant 80a locally at the processing locations 54 and removal of the modified substrate material 56. The already formed tempering channel section 42 is not exposed to, or at least to a reduced extent, unwanted etching attacks by the etchant 80a, which may be carried along by the collecting fluid 84, since the collecting fluid 84 does not flow through the already formed tempering channel section 42.

[0149] Figure 6 illustrates the processing system 40 and the method according to a third embodiment, in which there are two conveyor lines 60, which are designated 60.1 and 60.2 and whose functionally identical components are also marked with the respective index .1 and .2.

[0150] This concept is particularly applied when the etching medium 80' is a reaction-activatable precursor 80c; this is delivered to the processing locations 54 through the first supply line 64.1. A reactant designated 98, which converts the precursor 80c into the etchant 80a at the processing locations 54 in the desired manner, is delivered to the processing locations 54 through the second supply line 64.2.

[0151] The reaction-activatable precursor 80c is provided by a first flushing fluid 82.1 and the reactant 98 is provided by a second flushing fluid 82.2, wherein the first flushing fluid 82.1 is stored in the reservoir 68.1 of the first production line 60.1 and the second flushing fluid 82.2 is stored in the reservoir 68.2 of the second production line 60.2.

[0152] In order to ensure that the desired conversion to the etchant 80a occurs immediately after the precursor 80a and the reactant 98 emerge from the respective feed line 64.1 or 64.2, the discharge ends 66.1 or 66.2 and the associated discharge positions are arranged as close to one another as possible.

[0153] Figure 6A shows the two reservoirs 68.1, 68.2 with associated feed pumps 70.1, 70.2 in a modification in which two feed lines 60.1 and 60.2 are also used. However, in this modification, the first feed line 60.1 serves as the etching medium 80', delivering the etchant 80a as such or a temperature-activated precursor or photoactivatable precursor 80b with the aid of the rinsing fluid 82 through the first supply line 64.1 to the processing locations 54. The corresponding rinsing fluid 82 is stored in the reservoir 68.1 of the first feed line 60.1. In this modification, however, inert flushing medium 62 is stored in the reservoir 68.2 of the second conveyor line 60.2, whereby the processing locations 54 are also supplied with inert flushing fluid 62. In this case, the second conveyor line 60.2 defines an inert conveyor line.

[0154] In this way, for example, the concentration of the etching medium 80' at the processing locations 54 can be adjusted by a higher or lower release of inert rinsing fluid 62 with constant release of the etching medium 80' by the rinsing fluid 82 during the ongoing removal process.

[0155] Figure 7 shows a fourth embodiment of the processing system 40 and the method, in which the concept with two conveyor lines 60.1, 60.2 is also implemented and the suction device 86 is additionally provided. This assists, as described above, in ensuring that the etching effect of the etchant 80a present at the processing locations 54 is as locally limited as possible and occurs only in the immediate vicinity of the processing locations 54.

[0156] The modification according to Figure 6A, in which the processing locations 54 are exposed to etchant 80a or temperature-activatable precursor or photoactivatable precursor 80b and also to inert rinsing fluid 62, can also be carried out here. Figure 8 illustrates a fifth embodiment of the processing system 40 and the method, in which such a local limitation of the etching effect of the etchant 80a is supported by an auxiliary medium 100, which is supplied at a greater distance in front of the processing locations 54 than the etching medium 80'. In the variant shown in Figure 8, the etching medium 80' can be the etchant 80a as such or a temperature-activatable precursor or a photoactivatable precursor 80b.

[0157] Generally speaking, the collection fluid 84 is diluted and / or neutralized with the aid of the auxiliary medium 100.

[0158] For this purpose, there is an auxiliary medium conveying line designated 60.3, in which the same components 64 to 72 bear the corresponding index .3. The discharge position of the supply line 64.3 is always farther away from the processing locations 54 than the discharge position of the supply line 64.1. In other words, the discharge end 66.3 of the supply line 64.3 is always located further upstream of the processing locations 54 than the discharge end 66.1 of the supply line 64.1.

[0159] The auxiliary medium 100 can, for example, be inert rinsing fluid 62 or a neutralizing medium that neutralizes the etchant 80a. Depending on the etchant 80a present at the processing locations 54, appropriate bases or acids can be used as the neutralizing medium.

[0160] As a result, an area locally upstream of the processing locations 54 is exposed to the auxiliary medium 100 and flushed, so that the resulting collection fluid 84 no longer carries any etchant 80a or etchant 80a only in a low concentration, at which an etching reaction on the substrate material 12a along the already formed temperature control channel section 42 occurs only to a negligible extent. At the same time, the temperature of the collection fluid 84 is reduced by the inflowing auxiliary medium 100, which additionally reduces the reactivity of any existing etchant 80a. The etching medium 80' or the flushing fluid 82 can therefore optionally even be heated by a heating unit 101, shown in dashed lines in Figure 8, in order to locally increase the etching effect at the processing locations 54. However, due to the cooling by the auxiliary medium 100 mentioned above, there is no removal of the substrate material 12a along the tempering channel section 42.

[0161] Figure 9 shows, as a sixth embodiment of the processing system 40 and the method, how the concepts according to the third embodiment shown in Figure 6 and the fifth embodiment shown in Figure 7 can be combined. With the aid of the first conveyor line 60.1 and the second conveyor line 60.2, reaction-activatable precursor 80c and reactant 98 are applied to the processing locations 54, thereby producing etchant 80a there. By means of the third conveyor line 60.3, the auxiliary medium 100 is delivered locally in front of the processing locations 54 in the manner described above and with the described effect.

[0162] Here too, the modification according to Figure 6A can be carried out for the first and second conveyor lines 60.1 and 60.2.

[0163] If necessary, in the variants explained in relation to Figures 8 and 9, the suction device 86 can additionally be provided and the collecting fluid 84, which then also comprises the auxiliary medium 100, can be suctioned off.

[0164] 3. Obtained substrate

[0165] Figure 10 now again shows the substrate 12 in the stage of the carrier substrate 12" with hollow tempering structures 22, which were obtained by the method explained above and are again represented by way of example by three tempering channels 34.1, 34.2 and 34.3. The hollow tempering structures 22 each define an inner surface 102, wherein for the sake of clarity only one inner surface 102 is provided with a reference symbol. Properties of the hollow tempering structures 22 or of the tempering channels 34 and of the substrate 12 as such are explained below, which are possible when applying the method described above or result therefrom, wherein, where appropriate, properties already described are also taken up again and / or supplemented.

[0166] 3.1 Temperature control hollow structures / temperature control channels

[0167] By applying the method explained above for incorporating the tempering hollow structures 22, substrates 12 with tempering hollow structures 22 are obtained, the inner surface 102 of which has an extremely high quality with a mean roughness Ra between 10.0 pm and 5.0 pm, which can in particular be between 10.0 pm and 6.5 pm, between 10.0 pm and 8.0 pm, between 8.5 pm and 5.0 pm, between 7.0 pm and 5.0 pm or between 8.5 pm and 6.5 pm, or the inner surface 102 of which has an extremely high quality with a mean roughness Ra of 5.0 pm and less, which can be between 5.0 pm and 0.1 pm, between 4.5 pm and 0.125 pm, between 4.0 pm and 0.15 pm, between 3.5 pm and 0.175 pm or between 3.0 pm and 0.2 pm. In practice, particularly good mean roughness values ​​Ra between 0.1 pm and 0.5 pm, between 0.15 pm and 0.45 pm, between 0.2 pm and 0.4 pm, and between 0.25 pm and 0.35 pm have been achieved.In principle, however, mid-rough values ​​Ra between 10.0 pm and 5.0 pm are also a good result.

[0168] Figure 11A shows a topographic image of a surface region 104 of the inner surface 102 of such a tempering hollow structure 22, and Figure 11B shows a section along the section line designated 106 in Figure 11A, illustrating an average roughness Ra of approximately 0.28 pm achieved there. The surface region 104 has an extension of 254 pm x 190 pm.

[0169] The mean roughness values ​​Ra are determined and specified in accordance with DIN EN ISO 25178 (as of April 2023). The measurement was performed using a white light interferometer with 50x magnification, as is known per se. Figure 11A illustrates that by applying the method, a surface topography 108 is obtained, at least in surface areas of the inner surface 102 of the hollow tempering structures 22, whose geometric shape results from a superposition of countersunk structures 110 extending into the substrate material 12a.

[0170] This is additionally illustrated schematically in Figure 13 using a longitudinal section of a tempering cavity structure 22, with the proportions significantly exaggerated and without reference to the images of Figure 11A. Only the lower transition between the tempering cavity structure 22 and the substrate material 12a shown in Figure 13 will be discussed below. Seven countersink structures 110.1, 110.2, 110.3, 110.4, 110.5, 110.6, and 110.7 can be seen there as examples with solid lines, which extend into the substrate material 12a.

[0171] In Figure 13, dashed lines illustrate a reference lateral surface from which the countersunk structures 108 extend into the substrate material 12a. The superposition of these countersunk structures 110 then results in the surface topography 108, the course of which can be seen in the section shown in Figure 13 with a thicker solid line.

[0172] The surface topography 108 ultimately defines adjacent depression areas 112, between which peripheral regions 114 extend. In Figure 11, only a few of these depression areas and peripheral regions are provided with reference symbols.

[0173] Illustratively, these peripheral areas 114 form a kind of mountain ridge between two adjacent valleys in the form of two adjacent depressions 112. These peripheral areas 114 can in particular be linear.

[0174] The countersunk structures 110 can, in particular, be segments of bodies that are inherently point-symmetric or at least axially symmetric, such as spherical segments, ellipsoidal segments, or paraboloids. The resulting countersunk regions 112 can, in turn, be axially symmetric and, for example, follow a section of the outer surface of spherical segments, ellipsoidal segments, or paraboloids. In this case, their edge regions 114 are also axially symmetric. However, non-axisymmetric countersunk regions 112 with non-axisymmetric edge regions 114 can also arise and be present, as can be seen in Figure 11A based on the two countersunk regions designated 112 and their edge regions designated 114. The final geometry and dimension of a depression area 112 surrounded by a peripheral edge region 114 depends on the geometries and dimensions of the depression structures 110, which are understood as the basis for the formation of the depression area 112.For the sake of completeness, it should be noted that the countersunk structures 110 are distributed over the surface of the lateral surface 102, but Figure 13 can of course only show the section shown and no countersunk structures 110 and resulting countersunk regions 112 in front of and behind the paper plane.

[0175] A tempering channel 34 can have a diameter between 0.5 mm and 20 mm, with diameters between 1 mm and 5 mm being preferred.

[0176] The length of a temperature control channel 34 depends primarily on the dimension of the substrate 12 and is in practice at least 10 cm, but can also be at least 15 cm or at least 20 cm.

[0177] A temperature control channel 34 can be curved or at least have curved sections. As can be seen in Figure 22, the temperature control channels 34 follow the curvature of the support surface 14 in a central section 116 there, whereby this central section 116, which is thus already a curved section, extends between two sections 118 that are, in contrast, strongly curved. In Figure 22, only the central section 116 and the strongly curved sections 118 in the case of the temperature control channel 34.1 have a reference numeral. The central section 116 designated there opens on the left in Figure 22 into the strongly curved section 118 there, which in turn merges into a straight section 120 that then ends at the opening 36 of the temperature control channel 34.1. Figure 13 shows section XIII of Figure 10 on an enlarged scale. A strong curvature is understood to mean an angle of curvature between 60° and 120°, in particular between 80° and 100°, preferably of about 90°.Preferably, a section 116 of the tempering channel 34 extends between two strongly curved sections 118 with a curvature angle of approximately 90°, as shown in the present embodiment.

[0178] The curvature of a sharply curved section 118 usually follows an arc. For example, with a 90° bend, there are not two channel sections that are strictly perpendicular to each other.

[0179] An outer radius of curvature R, also illustrated in Figure 13, and the diameter D of a highly curved section, here the highly curved section 118, define a ratio R / D. Such a ratio R / D is preferably between 2 and 6, more preferably between 2.5 and 5, and especially preferably between 2.5 and 3.5.

[0180] These R / D ratios do not reflect Figure 13 or the other figures; for better visibility, the tempering channel 34.1 is shown schematically with a relatively larger diameter.

[0181] Relative to the support surface 14 of the substrate 12, a temperature control channel 34 extends, in particular, at a distance of 1.0 mm to 50.0 mm, 1.0 mm to 20.0 mm, 1.0 mm to 10.0 mm, or 1.0 mm to 5.0 mm. The distance is preferably determined relative to a normal to the support surface 14. The distance of the temperature control channel 34 from the support surface 14 can vary along its length.

[0182] 3.2 Substrat

[0183] Using the method explained above, a substrate 12 provided with hollow tempering structures 22 is obtained, having a support surface 14 whose dimensional stability exhibits significant time stability. The dimensional stability of the support surface 14 changes by less than 100 μm, in particular by less than 50 μm, and further in particular by less than 25 μm, over a service life of the substrate 12 of up to 10 years, at least up to five years, and at least up to two years.

[0184] This fit stability is also maintained in a mirror 10 comprising a substrate 12 produced by the methods explained above and provided with the coating 16. Consequently, a mirror 10 is obtained whose fit changes by less than 100 pm, in particular by less than 50 pm, and further in particular by less than 25 pm, over a service life of the mirror 10 of up to 10 years, at least up to five years, and at least up to two years.

[0185] The high stability of the fit of the support surface 14 of the substrate 12 and the fit of the mirror 10 produced therefrom is achieved by the fact that the modified substrate material 56 is removed precisely and purposefully, so that a substrate with a particularly homogeneous structure is obtained or restored after the structure no longer has this structural homogeneity when the modified substrate material 56 is still present.

[0186] This is reflected in Figures 14 A, B and C, which are reproductions of the results of measurements of the fit of the support surface 14 of a substrate 122 for a mirror, wherein a surface image representation of the support surface 14 is shown at the top and a deviation profile along a measurement section is shown below.

[0187] The measurements were performed using an interferometric measuring system based on a Fizeau interferometer, providing a repeatability of 10 pm PMS and a pixel size of typically 0.12 mm x 0.12 mm.

[0188] Figure 14A shows the fit of the support surface 14 for a substrate 122 in which the modified substrate material 56 is still present, which corresponds somewhat to the configuration of the substrate 12 according to Figure 3, as achieved using previously known methods. Depressions 124 are visible in the support surface 14, three of which are designated 124.1, 124.2, and 124.3 in the surface image representation and the deviation profile. These depressions 124 are located where the modified substrate material 56 is present below the support surface 14 in the substrate material 12a. As can be seen in Figure 14A, the depressions 124 follow the profiles of the modified substrate material 56, which in this case can be seen as straight channels. The measuring section of the respective deviation profile in Figures 14A, B, and C runs transversely to the channels.

[0189] For comparison purposes, the substrate 122 is not provided with corresponding channels with modified substrate material 56 under the full support surface 14; the area to the right of the depressions 124 is unprocessed.

[0190] The depressions 124 arise due to the structural inhomogeneities in the substrate material 12a caused there below the carrier surface 14 by the modified substrate material 56.

[0191] Figure 14B shows the fit of the support surface 14 for a substrate without the modified substrate material 56, which corresponds to the configuration of the substrate 12 according to Figure 10. As Figure 14B shows and is clear from the deviation profile, there are significantly smaller depressions 124 and the support surface 14 now has a smaller fit deviation overall.

[0192] Figure 14C shows a differential representation of the measurements according to Figures 14A and 14B and, in this context, also illustrates the largely unchanged areas of the carrier surface 14 without the underlying tempering hollow structures 22.

[0193] In any case, the pass measured according to Figure 14B exhibits the temporal stability explained above, which is also achieved with a substrate obtained by the method described here. 4. Semiconductor technology / projection exposure system

[0194] Figure 15 again illustrates a semiconductor technology system 6 using the example of a projection exposure system 200 for EUV semiconductor lithography. Other semiconductor technology systems, such as a mask inspection system or a wafer inspection system, sometimes contain the same or similar components as those explained here using the example of the EUV projection exposure system 200.

[0195] The projection exposure system 200 comprises an illumination system 202 with a radiation source 204 and illumination optics 206 for illuminating an object field 208 in an object plane 210, in which a reflective reticle 212 is arranged. In the illustrated embodiment, the radiation source 204 is an EUV radiation source that emits EUV radiation as working radiation 214, in particular in a wavelength range between 5 nm and 30 nm. The radiation source 204 can be a plasma source, for example, an LPP (Laser Produced Plasma) source or a GDPP (Gas Discharged Produced Plasma) source. Alternatively, a synchrotron-based radiation source or a free-electron laser (FEL) can be used as the radiation source 204.

[0196] Furthermore, the projection exposure system 200 includes projection optics 216 for imaging the object field 208 into an image field 218 located in an image plane 220 of the projection optics 216. A wafer bearing a light-sensitive layer (resist) is arranged in the image plane 220 as an example of an object 222. Components for the synchronous movement of the reticle 212 and the wafer 222 are only indicated in Figure 15 and are not provided with reference numerals.

[0197] The projection exposure system 200 comprises a plurality of optical elements 8 in the form of mirrors Mn, which are numbered according to their arrangement in the beam path of the projection exposure system 200. In the present case, a total of 10 mirrors M1 to M10 are present in the beam path. The mirrors M3 and M4 are designed as facet mirrors containing a plurality of individual mirrors. The remaining mirrors Mn are each a mirror 10 with a monolithic mirror substrate 12 and a coating 16 carried thereby, as shown by way of example in Figure 1. For the sake of simplicity, these mirrors are indicated as cuboids in Figure 15. However, the surfaces of the mirrors 10 exposed to the EUV radiation 214 and provided with the coating 16 are not planar in reality, but curved, as also illustrated in Figure 1.

[0198] Mirrors M1 to M4 in illumination system 206 serve to illuminate a section of reticle 212 with the desired illumination angle distribution. Mirrors M5 to M10 of projection optics 216 project this section in reduced size onto wafer 222. As a result, the structures contained in reticle 212 are imaged onto the light-sensitive layer supported by wafer 222.

[0199] With the aid of the optical elements 8, which in the present embodiment are designed as mirrors 10 for the EUV projection exposure system 200 and whose coating is at least designed to reflect at least 50% of EUV light incident vertically or almost vertically, the object 222 is irradiated with the working radiation 214.

[0200] The semiconductor technology system 6 is part of a manufacturing process with which a structured electronic component 224 can be manufactured, which is shown schematically in Figure 15 with generated structures 226 as the result of an overall manufacturing process that includes further steps in addition to the process in the semiconductor technology system 6. However, it is relevant here that the semiconductor technology system 6 includes at least one optical element 8 that was manufactured using one of the methods of the process variants explained above.

[0201] The structured electronic component 224 is in particular a computer chip 228, in the production of which a projection exposure system, here the projection exposure system 200, is used, as mentioned at the beginning.

[0202] 5. Concluding remarks

[0203] All of the above methods, steps, procedures, concepts and principles can be combined with each other, which is also reflected in the combinations of features specified in the claims.

Claims

PATENT CLAIMS 1. A method for incorporating hollow tempering structures (22) into a substrate (12), in particular into a substrate for an optical element, in particular for a mirror (10) for an EUV projection exposure system, comprising the following steps: (A) providing a substrate (12) consisting of a substrate material (12a); (B) Successively focusing a processing light beam (46) on processing locations (54) at which tempering hollow structures (22) are to be created, so that the substrate material (12a) is removed at the processing locations (54), whereby modified substrate material (58) is created adjacent to the processing locations (54), which has an increased susceptibility to a chemically active treatment medium relative to the substrate material (12a); (C) applying a rinsing fluid (82; 82.1) to the processing locations (54) while step (B) is being carried out, whereby removed substrate material is rinsed away; characterized in that in a step (D) the processing locations (54) are applied with a treatment medium (80) while step (B) is being carried out, wherein the treatment medium (80) exerts an effect at the processing locations (54) and removes modified substrate material (58) present there.

2. The method according to claim 1, characterized in that the chemically active treatment medium (80) is an etching medium (80'), an oxidizing agent or a reducing agent, and in particular is an etching medium (80') by means of which the modified substrate material (58) is removed by an etching process in step (D).

3. Method according to claim 1, characterized in that the chemically active treatment medium (80) is an etching medium (80') and a) the etching medium (80') as such is an etchant (80a); or b) the etching medium (80') is an etchant precursor (80b, 80c) from which an etchant can be produced at the processing locations (54), and in particular is a temperature-activatable precursor (80b) or a reaction-activatable precursor (80c) or a photoactivatable precursor (80b).

4. The method according to claim 3, characterized in that the etching medium (80') a) is an etchant (80a) in the form of hydrofluoric acid HF or potassium hydroxide KOH; or b) is an etchant precursor (80b, 80c) in the form of potassium hydrogen fluoride HKF2, ammonium hexafluorosilicate (NH^SiFe], calcium fluoride CaF2, sodium fluoride NaF, potassium fluoride KF, lithium fluoride LiF, ammonium hydrogen difluoride NH4HF2.

5. Method according to one of claims 1 to 4, characterized in that the chemically active treatment medium (80), in particular the etching medium (80'), is provided by the rinsing fluid (82, 82.1).

6. The method according to claim 5, characterized in that the chemically active treatment medium (80) is the etching medium (80') and a) the rinsing fluid (82) provides the etching medium (80') as an etchant (80a) or as a temperature-activatable etchant precursor (80b) from which an etchant is formed above a threshold temperature, or as a photoactivatable etchant precursor (80b) from which an etchant is formed by irradiation with an activation radiation; or b) the rinsing fluid is a first rinsing fluid (82.1) which provides a reaction-activatable etchant precursor (80c) from which etchant can be produced at the processing locations (54) by a reaction with a reactant (98), and the reactant (98) is provided by a second rinsing fluid (82.2).

7. Method according to claim 5 or 6, characterized in that the processing locations (54) are also exposed to an inert rinsing fluid (62).

8. Method according to one of claims 5 to 7, characterized in that collecting fluid (84) flowing away from the processing locations (54) is sucked away by means of a suction device (86).

9. Method according to one of claims 5 to 8, characterized in that collecting fluid (84) flowing away from the processing locations (54) is diluted and / or neutralized with the aid of an auxiliary medium (100).

10. A processing system for incorporating tempering hollow structures (22) into a substrate (12) of a mirror (10) for an EUV projection exposure system according to the method according to one of claims 1 to 9, comprising a) a light source (44) with which a processing light beam (46) can be generated; b) a focusing device (48, 50) by means of which the processing light beam (46) can be focused on processing locations (54) at which tempering hollow structures (22) are to be created, so that the substrate material (12a) is removed at the processing locations (54), whereby modified substrate material (58) is created adjacent to the processing locations (54), which has an increased susceptibility to a chemically active treatment medium relative to the substrate material (12a); c) a fluid device (58) by means of which the processing locations (54) can be subjected to a rinsing fluid (82; 82.1), whereby removed substrate material is rinsed away; characterized in that d) the fluid device (58) is set up such that the processing locations (54) are subjected to a treatment medium (80) while the focusing device (48, 50) is in operation and the processing light beam (46) is focused onto the processing locations (54), wherein the treatment medium (80) exerts an effect at the processing locations (54) and removes modified substrate material (58) present there.

11. Processing system according to claim 10, characterized in that the chemically active treatment medium (80) is an etching medium (80'), an oxidizing agent or a reducing agent, and in particular is an etching medium (80') by which the modified substrate material (58) is removed by an etching process.

12. Processing system according to claim 10 or 11, characterized in that the chemically active treatment medium (80) is an etching medium (80') and a) the etching medium (80') as such is an etchant (80a); or b) the etching medium (80') is an etchant precursor (80b, 80c) from which an etchant can be formed at the processing locations (54), and in particular is a temperature-activatable precursor (80b) or a reaction-activatable precursor (80c) or a photoactivatable precursor (80b).

13. Processing system according to claim 12, characterized in that the etching medium (80') a) is an etchant (80a) in the form of hydrofluoric acid HF or potassium hydroxide KOH; or b) an etchant precursor (80b, 80c) in the form of potassium hydrogen fluoride HKF2, ammonium hexafluorosilicate (NFUMSiFe], calcium fluoride CaFz, sodium fluoride NaF, potassium fluoride KF, lithium fluoride LiF, ammonium hydrogen difluoride NH4HF2.

14. Processing system according to one of claims 10 to 13, characterized in that the fluid device (58) comprises a conveyor line (60, 60.1) with a supply line (64, 64.1) which has a discharge end (66, 66.1) and is connected to a reservoir (68, 68.1) in which a rinsing fluid (82, 82.1) is kept, which provides the treatment medium (80).

15. Processing system according to claim 14, characterized in that the chemically active treatment medium (80) is the etching medium (80') and a) the rinsing fluid (82) provides the etching medium (80') as an etchant (80a) or as a temperature-activatable etchant precursor (80b) from which an etchant is formed above a threshold temperature, or as a photoactivatable etchant precursor (80b) from which an etchant is formed by irradiation with an activating radiation; or b) the conveyor string (60.1) is a first conveyor string (60.1) and the rinsing fluid defines a first rinsing fluid (82.1) which provides a reaction-activatable etchant precursor (80c) from which etchant can be produced at the processing locations (54) by a reaction with a reactant (98), and there is a second conveyor string (60.2) with a second supply line (60.2) which has a discharge end (66.2) and is connected to a second reservoir (68.2) in which a second rinsing fluid (82.2) which provides the reactant (98).

16. Processing system according to one of claims 14 or 15, characterized in that the fluid device (58) comprises an inert conveyor line (60.2) with a supply line (64.2) which has a discharge end (66.2) and is connected to a reservoir (68.2) in which an inert rinsing fluid (62) is stored.

17. Processing system according to one of claims 14 to 16, characterized in that each existing conveyor line (60, 60.1, 60.2) comprises a line conveyor (72, 72.1, 72.2) by means of which the respective discharge end (66, 66.1, 66.2) of the feed line (64, 64.1, 64.2) can be tracked to the processing locations (54).

18. Machining system according to one of claims 14 to 17, characterized in that the fluid device (58) comprises a suction device (86) with a suction line (88) which has a suction end (90) and is connected to a suction pump (94) by means of which collecting fluid (84) flowing away from the machining locations (54) can be sucked away.

19. Processing system according to claim 18, characterized in that the suction device (86) comprises a line conveyor (92) by means of which the suction end (90) of the suction line (88) can be guided to the processing locations (54), in particular at a greater distance from the processing locations (54) than the discharge end(s) (66, 66.1, 66.2) of one or more supply lines (64, 64.1, 64.2).

20. Processing system according to one of claims 14 to 19, characterized in that the fluid device (58) comprises an auxiliary medium conveying line (60.3) with a supply line (64.3) which has a discharge end (66.3) and is connected to a reservoir (68.3) in which an auxiliary medium (100) is kept, in particular an inert rinsing fluid (62) or a neutralizing medium which can neutralize the treatment medium (80a).

21. Processing system according to claim 20, characterized in that the auxiliary medium conveying line (60.3) comprises a line conveyor (72.3), by means of which the discharge end (66.3) of the supply line (64.3) can be guided to the processing locations (54), in particular at a greater distance from the processing locations (54) than the or the discharge ends (66, 66.1, 66.2) of one or more feed lines (64, 64.1, 64.2) of the other conveyor lines (60, 60.1, 60.2).

22. Method for producing an optical element, in particular for producing a mirror (10) for an EUV projection exposure system, characterized in that tempering hollow structures (22) are incorporated into the substrate (12) according to the method according to one of claims 1 to 9 and further processing comprises one or more steps of chemical and / or physical processing of at least one surface of the substrate (12) and the production or application of a coating (16) to the substrate (12) which is at least designed to reflect at least 50% of EUV light incident perpendicularly or almost perpendicularly.

23. Substrate for producing an optical element, in particular for producing a mirror (10) for an EUV projection exposure system, wherein the substrate (12) has tempering hollow structures (22), in particular tempering hollow structures (22) which are incorporated into the substrate (12) according to the method according to one of claims 1 to 9, characterized in that at least one tempering hollow structure (22) defines an inner lateral surface (102) which, at least in regions, has a mean roughness Ra according to DIN EN ISO 25178, as of 04 / 2023, between 10.0 pm and 5.0 pm, which is in particular between 10.0 pm and 6.5 pm, between 10.0 pm and 8.0 pm, between 8.5 pm and 5.0 pm, between 7.0 pm and 5.0 pm or between 8.5 pm and 6.5 pm, or which, at least in regions, has a mean roughness Ra of 5.0 pm and less, in particular between 5.0 pm and 0.1 pm, between 4.5 pm and 0.125 pm, between 4.0 pm and 0.15 pm, between 3.5 pm and 0.175 pm or between 3.0 pm and 0.2 pm., 24. Substrate for producing an optical element, in particular for producing a mirror (10) for an EUV projection exposure system, wherein the substrate (12) has tempering hollow structures (22), in particular tempering hollow structures (22) which are incorporated into the substrate (12) according to the method according to one of claims 1 to 9, characterized in that at least one tempering hollow structure (22) defines an inner lateral surface (102) which has a surface topography (108) whose geometric shape results from a superposition of countersunk structures (110) which extend into a substrate material (12a) of the substrate (12).

25. Substrate according to claim 24, characterized in that one or more countersunk structures (110) are segments of bodies that are point-symmetric or at least axisymmetric.

26. Substrate according to claim 24 or 25, characterized in that the surface topography (108) defines adjacent depression regions (112) between which edge regions (114), in particular linear edge regions (114), run.

27. Substrate according to claim 26, characterized in that one or more countersunk regions (112) are axisymmetric or non-axisymmetric.

28. Substrate according to claim 27, characterized in that an axisymmetric countersunk region (112) follows a portion of the outer surface of a spherical segment, an ellipsoidal segment or a paraboloid.

29. Substrate according to one of claims 23 to 28, characterized in that at least one tempering hollow structure (22) is a tempering channel (34) which has one or more of the following features: a) the temperature control channel (34) has a diameter between 0.5 mm and 20 mm, preferably between 1 mm and 5 mm; b) the temperature control channel (34) has a length of at least 10 cm, at least 15 cm, or at least 20 cm. c) the temperature control channel (34) is curved or has at least one curved section (116; 118); d) the temperature control channel (34) has a section (116) that follows the curvature of a support surface (14) for a coating (16) of the substrate (12); e) the temperature control channel (34) has a strongly curved section (118) that has an angle of curvature between 60° and 120°, in particular between 80° and 100°, preferably of approximately 90°; f) the tempering channel (34) has a strongly curved section (118) which has an angle of curvature between 60° and 120°, in particular between 80° and 100°, preferably of approximately 90°, and follows an arc;g) the temperature control channel (34) has a strongly curved section (118) which has an angle of curvature between 60° and 120°, in particular between 80° and 100°, preferably of approximately 90°, and follows an arc and defines an outer radius of curvature R and a diameter D, wherein a ratio R / D of the radius of curvature R to the diameter D is between 2 and 6, preferably between 2.5 and 5, and particularly preferably between 2.5 and 3.5; h) the temperature control channel (34) runs at a distance of 1.0 mm to 50.0 mm, from 1.0 mm to 20.0 mm, from 1.0 mm to 10.0 mm, or from 1.0 mm to 5.0 mm relative to a support surface (14) for a coating (16) of the substrate (12); 30. Substrate for producing an optical element (8), in particular for producing a mirror (10) for an EUV projection exposure system, which has tempering hollow structures (22), in particular tempering hollow structures (22) which are incorporated into the substrate (12) according to the method according to one of claims 1 to 9, and defines a carrier surface (14) for a coating (16), characterized in that the fit of the carrier surface (14) changes by less than 100 pm, in particular by less than 50 pm and further in particular by less than 25 pm over a service life of the substrate (12) of up to 10 years, at least up to five years and at least up to two years.

31. Substrate having the features of claim 23 and having the features of at least one of claims 24 to 29.

32. Substrate having the features of claims 30 and 31.

33. Substrate according to one of claims 23 to 32, characterized in that tempering hollow structures (22) are incorporated according to the method according to one of claims 1 to 9.

34. Optical element, in particular a mirror (10) for an EUV projection exposure system, with a substrate (12), characterized in that the substrate (12) is a substrate (12) according to one of claims 23 to 32.

35. Optical element, in particular mirror (10) for an EUV projection exposure system, with a substrate (12), in particular optical element according to claim 34, characterized in that the fit of the optical element (8) with a service life of the optical element of up to 10 years, at least up to five years and at least up to two years by less than 100 pm, in particular by less than 50 pm and further in particular by less than 25 pm.

36. Optical element according to one of claims 34 or 35, characterized in that the optical element (8) is a mirror (10) for an EUV projection exposure system, wherein the substrate (12) has a carrier surface (14) which carries a multilayer coating (16) which is at least designed to reflect at least 50% of perpendicularly or nearly perpendicularly incident EUV light.

37. Optical element according to claims 36 and 35 and 34.

38. A semiconductor technology system, in particular an EUV projection exposure system (200), a mask inspection system or a wafer inspection system, in which an object (222) can be irradiated with a working radiation (214) using at least one optical element (8), characterized in that the optical element (8) is an optical element (8) according to one of claims 34 to 37.

39. System according to claim 38, characterized in that the system (6) is an EUV projection exposure system (200) and that the at least one optical element (8) is a mirror (10) according to claim 36.

40. Structured electronic component, characterized in that the structured electronic component (224) was manufactured using a semiconductor technology system (6) according to claim 38 or 39 and using at least one optical element (8) according to one of claims 34 to 37.

Images