DE102017221388A1 - Method for producing a component through which a cooling fluid can flow, optical element and EUV lithography system - Google Patents

Abstract

The invention relates to a method for producing a component through which a cooling fluid can flow for a lithography system, comprising the steps of: surrounding a tube section (1), which is arranged inside a capsule (2), with a powdery filling material (3), wherein at least one End (4a) of the pipe section (1) protrudes from the capsule (2), and producing the component by hot isostatic pressing of the in the capsule (2) arranged powdery filling material (3). The invention also relates to an optical element for reflection of radiation, comprising: a base body having a substrate (6) having a surface (7) to which a reflective coating is applied, the substrate (6) comprising at least one with a cooling fluid having flow-through pipe section (1). The substrate (6) is produced by mechanical compacting and sintering, in particular by hot isostatic pressing. The tube section (1) extends to a distance of less than 5 mm, preferably less than 3 mm, to the surface (7) and / or the substrate (6) is made of glass, for example of titanium-doped quartz glass. The invention also relates to a lithography system with at least one such optical element.

Description

Background of the invention

The invention relates to a method for producing a component through which a cooling fluid can flow for a lithography system, in particular for a lithography system, for example for an EUV lithography system, an optical element for the reflection of radiation, comprising: a base body with a substrate adjacent to a surface to which a reflective coating is applied, wherein the substrate has at least one pipe section of at least one tube through which a cooling fluid can flow, and a lithography system, for example an EUV lithography system, with at least one such optical element.

For the purposes of this application, a lithography system is understood to mean an optical system or an optical arrangement for lithography, i. an optical system which can be used in the field of lithography. In addition to a lithography system, for example an EUV lithography system (operating wavelength between about 2 nm and about 20 nm, in particular at about 13.5 nm) or a VUV lithography system (operating wavelength between about 150 nm and about 250 nm, for example 248 nm, 193 nm, 157 nm), which is used for the production of semiconductor components, the optical system can be, for example, an inspection system for inspecting a photomask used in a lithography system (also referred to below as a reticle) for inspecting a semiconductor substrate to be patterned (also referred to as wafer hereinafter) or a metrology system which is used to measure a lithography system or parts thereof, for example for measuring a projection system.

Components for the beam generating system, the illumination system, and the projection optics of an EUV lithography system such as collector mirrors, grazing incidence mirrors, facet mirror facets, or force frame support frames, must often be actively cooled dissipate the radiation power of the incident EUV radiation and possibly incident IR radiation of a pump laser, which is needed to generate the EUV radiation, or to ensure very constant temperatures at the components. Even with optical components of a DUV or VUV lithography system, for example mirrors used there, active cooling may be required. For the active cooling cooling channels must be integrated into the components themselves or in connected to the components via thermal bridges cooling channels, which are traversed by water or other usually liquid cooling medium.

For this purpose, cooling channels can be milled into a substrate, eroded or, in the case of ceramic substrates, for example SiSiC, shaped as a green body. On the substrate, a cover plate is welded, soldered, milled or bonded. This method entails a large manufacturing effort and the risk of leaks. Further, the inner surfaces of the cooling channels are not formed streamlined, and it can lead to shunts when the cover plate does not completely seal the channel walls with each other. Also, to prevent leakage, the cover plate must have a certain thickness, i. the cooling channels are further below the surface to be cooled than would be desirable in many cases.

From the DE 10 2009 039 400 A1 is a reflective optical element for use in an EUV system has become known, which has a base body which is at least partially made of a substrate material, wherein in the base body at least one cooling channel is arranged, which is traversed by a cooling medium. As substrate material, a material is provided, which has a thermal conductivity greater than 50 W / mK. The reflective optical element comprises a polishing layer which is applied to the substrate material and which has an amorphous material which can be processed by means of a polish. To produce the base body from a metal composite substrate, a tube made of a material having a higher melting temperature than the substrate material is used in casting the blank into a casting mold and poured in by filling the casting mold with melt. Such a tube may for example be made of stainless steel, nickel, a nickel alloy or another material whose thermal expansion coefficient is as close as possible to the thermal expansion coefficient of the substrate material.

From the DE 10 2015 210 045 A1 For example, a method for producing a heat sink and a heat sink for a lithography system have become known. The method comprises the following steps: a) arranging a tube for conducting a cooling fluid at least partially in a mold b) surrounding a part of the tube arranged inside the mold with filling material, and c) solidifying the filling material to form the Heatsink. The filling material can be filled into the mold, for example as granules or powder, and solidified in step c) by sintering.

Object of the invention

The object of the invention is to provide a method for producing a component through which a cooling fluid can flow as well as an optical element and an EUV lithography system with an improved cooling effect.

Subject of the invention

This object is achieved by a method for producing a component through which a cooling fluid can flow for a lithography system, comprising the steps of: surrounding a tube section through which the cooling fluid can flow within a capsule with a pulverulent filling material, wherein at least one end of the tube section protrudes from the capsule , and producing the component by hot isostatic pressing of the powdery filling material arranged in the capsule.

It is well known that in hot isostatic pressing a powder can be compacted, eliminating closed pores while maintaining open pores, cf. for example, the brochure "Introduction to PM HIP technology" of the EPMA (European Powder Metallurgy Association), available at "www.epma.com/epma-free-publications". The brochure also includes examples of standard powder alloys that can be hot isostatically compacted, such as stainless steels, tool steels, high speed steels, and Ni or Co based alloys.

According to the invention, it is proposed to produce a component for lithography, in particular for EUV lithography, for example a heat sink or a preform of a substrate for a (reflective) optical element by hot isostatic pressing. In the method, the tube section is typically first arranged in the capsule, for example a tin can. The powdery filling material is subsequently introduced into the capsule and surrounds the tube section. After introduction of the powder, the capsule is typically hermetically sealed, for example welded, whereby the tube section, which may for example be curved, is retained during hot isostatic pressing, since at least one end of the tube section projects out of the capsule or out of the capsule. After hot isostatic pressing, the capsule is removed leaving a component containing the tube section firmly bonded to the solidified powder. The pipe section is usually led out of the component at its two ends. After removing the capsule, for example, the tube section can be ground flat and a groove for an O-ring can be introduced in order to be able to flanged directly onto the tube section. The pipe section can also be provided at one or both ends with a flange to connect it with other pipe sections.

If the component is a substrate for a reflective optical element, then it has a surface facing the impinging radiation during operation of the optical element, the geometry of which may already be essentially predetermined during hot isostatic pressing. This surface and the surface area adjacent volume region of the substrate in which the or the pipe sections for the flow of the cooling medium are formed, form a substantially monolithic unit. With this substantially monolithic substrate it is possible, if necessary, to connect further elements or structures, which are e.g. increase the rigidity and which together with the substrate form a base body of the optical element. Optionally, the optical surface of the optical element may not be formed on the substrate of the base body but on such a (reinforcing) structure. In this case, it is required that the structure has a high surface quality at least on the side where the optical surface is formed. Optionally, the quality of the surface after hot isostatic pressing e.g. be increased by polishing.

In a variant of the method, a shaped body is inserted into the capsule prior to the hot isostatic pressing, which has at least one surface which is adapted to the geometry of a surface of the component to be produced, wherein the surface of the shaped body is preferably concave or convexly curved. The molded body typically has a higher melting point and a greater strength than the powder material with which the capsule is filled, so that this, in particular its surface, does not deform or only slightly deforms during hot isostatic pressing. The surface of the shaped body may have a concave or convex curvature, which is adapted to the curvature of a surface of the component, for example a substrate for an optical element, in order to (rough) its surface contour. pretend. For example, in the case of a substrate which has a (strongly) concavely curved surface for reflection of radiation, as is typically the case with a collector mirror, the surface of the shaped body may be provided with a correspondingly large counter-rotating (convex) curvature.

In a further variant, a reinforcing structure is inserted before the hot isostatic pressing in the capsule, which connects in the hot isostatic pressing with the powdery filler. In contrast to the above-described molded article, which is typically removed after hot isostatic pressing, the reinforcing structure is formed of a material which permanently bonds to the powdery filler during hot isostatic pressing, i. It creates a solid-powder composite. For example, the reinforcing structure may be a previously hot isostatically pressed component, or a conventionally cast, forged, or rolled component that is milled into shape and placed in the capsule where it remains after removal of the capsule.

By using a (typically preformed) conventionally made reinforcing member, the manufacturing cost of the component can be reduced because conventionally produced material is generally much cheaper than material made by mechanical compacting and sintering. The reinforcing structure may, for example, be a plate, which is formed in particular from a metallic material. The or the pipe sections can be easily positioned on a solid, such as metallic plate three-dimensional than is the case with the attachment only to the capsule or at openings of the capsule. Also, a capsule without a molded body or a reinforcing structure in the hot isostatic pressing, if necessary, significantly deform, which can lead to an undesirable deformation of the pipe sections.

In an advantageous development of the portion of the tube with a powdery filler in the form of a metallic powder, preferably a dispersion-hardened copper powder, a preferably dispersion-hardened aluminum powder or in the form of a ceramic powder is surrounded, wherein the tube is preferably made of a metallic material, in particular copper, aluminum or made of stainless steel. The metallic powder may be, for example, copper, aluminum or iron powder, ... or a copper, aluminum or iron alloy or mixtures thereof. Dispersion-hardened copper has almost the same coefficient of thermal expansion as pure copper, which can be used, for example, for the production of the pipe section (see above) and is also available in powder form.

Also, aluminum powder, in particular aluminum alloys or dispersion-hardened aluminum, have proven to be advantageous, because there are a number of components made of aluminum, which are suitable for replacement with such a powder metallurgical material, since these materials due to the small foreign phases usually only have a low corrosion and can be easily introduced into these cooling channels. However, dispersion hardened aluminum typically contains a lot of silicon, which may not be compatible with the hydrogen-containing plasma that exists in the vacuum environment of an EUV lithography system. In order to protect components made of dispersion-hardened aluminum from the plasma, protective measures may be expedient, for example a barrier layer of an inert material, e.g. made of silver, which is applied externally to the component or which surrounds the silicon particles.

The ceramic powder may be, for example, SiC or SiSiC (Si-filtered silicon carbide). The ceramic powder can already be the finished ceramic by hot isostatic pressing. Alternatively, after the hot isostatic pressing, a green body can be obtained, from which a finished ceramic is formed only by a subsequent chemical treatment and / or by subsequent tempering steps. A ceramic or metallic component can be used, for example, as a substrate for a mirror in the beam generation system or in the illumination system of an EUV lithography system, for example for a collector mirror.

In a further variant, the pipe section is surrounded by a powdery filler material in the form of glass powder, preferably in the form of in particular titanium-doped quartz glass powder, and the tube is formed of glass, preferably of titanium-doped quartz glass in particular. Since hot isostatic pressing is compacted and melted in one step, the shrinkage during sintering is eliminated, so that by using one or more press molds, it is possible to work significantly closer to the final shape or to the final geometry of the component than in the case of a separate, the sintering step following the densification would be the case.

The cooling channels can be inserted into the capsule in the form of drawn and shaped tubes or pipe sections of, for example, titanium-doped quartz glass. This allows great freedom in manufacturing the cooling channels, which can be achieved with none of the methods previously used for the production of components made of quartz glass, in which the cooling channels are typically produced by milling and bonding. Also, cavities in the component, which serve to save weight, can be planned much more flexibly than would be possible with a conventional production by milling and bonding. A component made of glass, in particular of titanium-doped quartz glass, for example of ULE®, or of a glass ceramic, eg of Zerodur®, can be used, for example, as a substrate for an EUV mirror in the projection optics of an EUV lithography system. It is understood that a glass ceramic powder or another powdery material can also be used as the powdery filling material.

In a further variant, the capsule is formed by vitrifying the surface of the usually already precompressed powdery filling material. The typically precompressed powder material in this case forms a porous body in which the pipe section is embedded. In this case, can be dispensed with the hot isostatic pressing usually required tin can because the porous body or the powder is glazed surface by laser bombardment or by short furnace annealing, so that the filler or its glazed surface itself forms the capsule. The remaining in the interior of the porous body porosity consists in this case only of closed pores that can be pressed directly hot isostatic.

The invention also relates to an optical element of the type mentioned, in which the substrate is produced by mechanical compression and sintering, in particular by hot isostatic pressing, and in which the pipe section up to a distance of less than 5 mm, preferably less than 3 mm , reaching the surface. Production by mechanical compaction and sintering is understood to mean that the substrate is formed by a mechanical compaction of a non-compelling metallic powder, e.g. in a mold or a press, and simultaneous or subsequent sintering of the thus-obtained "green compact" at high temperatures or hot rolling is formed into a (substantially) monolithic member.

The preparation of the substrate may be carried out in particular by means of the method described above, i. by hot isostatic pressing done. Production by cold isostatic pressing or uniaxial compaction with subsequent sintering is also possible, in each case a (substantially) monolithic substrate being obtained. In the substrate produced in this way, the pipe section (s) may be mounted in the immediate vicinity of the surface of the substrate to be cooled, to which the reflective coating is applied.

In one embodiment, the substrate is formed of a metal or a metal alloy, preferably of dispersion-hardened copper, or of a ceramic. As described above, such a substrate material can be used, for example, for producing a mirror for a beam generating system or an illumination system of an EUV lithography system. In particular, copper, especially dispersion-hardened copper, is well suited for the production of such a substrate, as shown in the following table, the density p, the thermal conductivity λ, the modulus of elasticity E and the coefficient of thermal expansion CTE can be found for different materials. In general, in the case of metals, naturally hard or dispersion-hardened alloys are to be preferred to the precipitation-hardened alloys. table ρ λ (W / mK) E (GPa) CTE (10 ^-6 / K) SiSiC 3.05 160-200 280 - 420 2-3 copper 8.92 400 100 - 130 16.5 Glidcop AL15 8.9 > 360 132 15.8 - 16.3 aluminum 2.7 235 70 23.1 Glidcop AL25 8.86 344 130 16.6 AlMg5 (EN AW 5019) 2.64 110-140 70 24.1 Osprey CE11F 2.5 149 121 11.4 AlSiC 9 3.0 200 188 8.0 W80 Cu20 15.6 220 28C 8.3 Mo85 Cu15 10 160 230 6.2 AlMg4.5Mn0.7 (EN AW 5083) 2.66 110-140 7C 24.1 Invar 8th 13 140 - 150 0.55-1.7 ULE 2.2 1.31 67.6 0 Al ₂ O ₃ 3.8 20-30 350 8th ZrO ₂ 2.7 2.5 250 11 AlN 3.3 200 320 5 cordierite 2.6 3 70 1.7 quartz glass 2.2 1.38 71 0.55

The material, which is listed under the trade name Glidcop® AL-15 in the table above, is a dispersion-hardened copper or a copper alloy in which 0.3% by weight of nanoparticles of Al ₂ O ₃ ensure that that grain migration or grain growth does not occur. This material has practically the same thermal expansion coefficient as copper and typically> 92% of the thermal conductivity of pure copper. Glidcop® AL-25 has similar properties, with the proportion of Al ₂ O ₃ nanoparticles being 0.5% by weight. In the variant LOX, eg Glidcop® AL-15 LOX, this material is resistant to hydrogen embrittlement. Controlled addition of boron in this material prevents oxidation of the copper particles after reduction, which is the last hot process step in powder production. Also, additives of other materials or elements, such as metals, in addition to metal oxides may be used to enhance certain material properties of Glidcop®, for example to reduce the thermal expansion coefficient to increase hardness or to reduce creep, eg Nb, Mo, W, Kovar, Alloy 42. Also additives for improving the strength and the thermal conductivity, for example in the form of graphite, diamond, SiSiC, carbon nanotubes, etc. are possible. It is understood that other dispersion-hardened copper materials, for example DSC from Chemet GmbH or CEP Discup® from CEP GmbH, as well as dispersion-hardened aluminum alloys can be used as materials for the substrate.

The thermal conductivity of dispersion-hardened copper is more than twice that of SiSiC. In addition, with this material, cooling channels can generally be made finer and brought closer to the reflective surface than SiSiC. It is also possible to separate in the substrate, i. to provide individually controllable cooling channels to produce a location-dependent varying cooling effect on the surface. In particular, it is also possible to mount heaters or heating elements at different depths in the substrate and in this way to actively regulate the curvature of the surface of the mirror.

The density of dispersion-hardened copper is almost three times that of SiSiC, with about 2.5 times lower modulus of elasticity at the same time. It may therefore be beneficial to reduce the mass of the substrate to introduce blind holes or ribs in the back of the substrate. These blind holes or ribs can already be produced in the hot isostatic pressing by introducing a (further) shaped body into the capsule or subsequently introduced by eroding or milling or chemical etching or dissolution in a suitable solvent in the substrate, the processing much cheaper than SiSiC is to execute.

In one embodiment, a lining of metal and / or plastic is attached to the inside of the pipe section. The e. G. curved pipe section (s) or cooling loops can be made for example of copper or copper pipe or of another suitable, usually metallic material. Because of other elements of the cooling circuit, it may be convenient, the tubes or pipe sections on its inside with a lining of aluminum, another metal, for example in the form of a thin, smooth or corrugated tube made of stainless steel, applied after hot isostatic pressing plastic coating or to provide a hose liner or a plastic hose. Alternatively, as a lining on the inside of the pipe sections or thin tubes made of stainless steel or aluminum can be introduced, which, however, may lead to tensions with temperature changes due to different thermal expansion coefficients compared to the material of the pipe section.

In another embodiment, the (monolithic) substrate extends at least 3 cm from the surface. Typically, all of the pipe sections introduced into the substrate to cool the surface are spaced less than 3 cm from the surface, as this is beneficial for good surface cooling or heat input.

In a further embodiment, the optical element is designed as a collector mirror for bundling EUV radiation, which emanates from a substantially punctiform EUV radiation source. In this case, the surface of the substrate is typically concavely curved and may, for example, form a cup-shaped portion of a rotational ellipsoid or a rotational paraboloid. As a rule, the collector mirror does not only have to reflect the incident EUV radiation, which is partially absorbed by the substrate, the collector mirror also usually encounters IR radiation which is generated by a pump laser and which also partially is absorbed by the substrate.

The substrate of the collector mirror can be formed, for example, from dispersion-hardened copper, in particular from Gildcop® AL, in which at least one pipe section is embedded as a cooling channel or as a cooling loop. The pipe section may be connected at a respective end projecting from the substrate with directly soldered or welded metallic bellows and / or flanges which form parts of a cooling circuit for feeding and discharging the cooling fluid into and out of the pipe section. Applied to the surface of the substrate is an EUV radiation-reflecting coating, which is typically formed as a multilayer coating with alternating layers with different (high or low refractive index) refractive indices. The materials of the high and low refractive layers of the multilayer coating depend on the wavelength of the EUV radiation to be reflected on the optical element. At a wavelength of about 13.5 nm, the multilayer coating typically has alternating layers of silicon and molybdenum, but other material combinations are also possible. On the reflective coating, a cover layer may be applied, which is formed for example of one or more metal oxides or a metal, for example of ruthenium.

In a further development, a grating structure for diffracting IR radiation is formed on the surface of the substrate or on a metallic layer which is provided between the substrate and the reflective coating. As described above, radiation from the pump laser, typically an IR laser, which is directed to a target material, typically in the form of tin droplets, also impinges on the collector mirror. In order to avoid collimating the IR radiation together with the EUV radiation in the EUV beam path, a grating structure having a period length corresponding to the wavelength of the IR radiation, e.g. at about 10.6 microns, adapted to diffract the IR radiation from the EUV beam path out. The diffraction grating can be incorporated directly into the material of the substrate, but it is also possible for the diffraction grating or the grating structure to be formed into a metallic layer, e.g. of silver formed between the substrate and the reflective coating to improve hydrogen resistance.

In a further embodiment, the base body has a reinforcing structure of a preferably metallic material, which is attached to the substrate or is connected to the substrate by mechanical compression and sintering, in particular by hot isostatic pressing. The reinforcing structure may be, for example, rolled metallic material, for example, copper or a copper alloy, e.g. in the form of Glidcop®. The reinforcing structure may be at the back, i. be attached to the reflective coating facing away from the surface of the substrate or the base body to increase its strength. For example, the reinforcing structure can be soldered, welded, glued, screwed or riveted on the back of the substrate.

For a substrate which itself is formed of a copper alloy, for example of Glidcop®, it is advantageous if the stiffening structure itself is made of a copper alloy, e.g. Glidcop®, since this has the same coefficient of thermal expansion as the substrate itself, so that only slight deformations of the substrate or the EUV radiation reflecting surface of the optical element occur with temperature changes.

Alternatively, in hot isostatic pressing or by another powder metallurgy process, the reinforcing structure may be bonded to the substrate, ie, a solid-powder composite is formed. The reinforcing structure can also be formed in this case, for example, from a milled block of the same material as the powder material. The ingot may be either conventionally prepared, ie cast and / or rolled, for example, or prepared in a preliminary step by hot isostatic pressing. As described above, the connection structure is in the capsule is inserted and combines with the powder of the substrate, so that it becomes an integral part of the body. On such a (rear) connection structure of the pipe sections or can be very well build and fix with fasteners, for example in the form of brackets. This procedure has the advantage that the tubes are exposed to less distortion during hot isostatic pressing.

It is also possible to mount the connection structure or the support on that side in the capsule on which the surface is formed, on which the reflective coating is applied. This is particularly favorable in the case that very small and precise distances of the or the pipe sections of this surface are required, for example, if the positioning accuracy of the pipe sections should be less than about 1 mm. In this case, for example, the reinforcing structure may be made of a block produced by hydrostatic pressing, which is milled, because coarse grains and foreign phases near this surface are troublesome because they adversely affect the mating and coatability.

In a further embodiment, the substrate has a porosity of less than 1%, preferably less than 0.1%, in particular less than 0.01%, i. the substrate contains almost no pores. The porosity is defined herein as the ratio of the volume of voids in the substrate to the total volume, i. to the sum of the volume of the voids and the solid volume of the substrate.

Another aspect of the invention relates to an optical element of the type mentioned, in which the substrate is made by mechanical compression and sintering, in particular by hot isostatic pressing, and made of glass, preferably made of particular titanoted quartz glass, wherein the at least one with the Cooling fluid can be flowed through pipe section preferably made of glass, particularly preferably made of titanium-doped particular quartz glass. Also in this case, the main body may have a reinforcing structure which is bonded to the substrate by hot isostatic pressing or by another powder metallurgy process.

Reflective optical elements in a projection optical system of an EUV lithography system are typically produced from a (glass) ceramic, for example from Zeodur®, or from titanium-doped quartz glass. The titanium-doped quartz glass is either deposited directly from the flame (Corning ULE®) or initially deposited as a powder (soot) and later sintered into a glass body (Heraeus Suprasil® ZE). In all cases, a solid glass body is produced, which is subsequently sanded. Lightweight structures can be made by bonding webs, but are expensive. Cooling channels near the surface, which is provided with the reflective coating, were previously considered unrealizable.

Another problem with the titanium-doped quartz glasses is that the thermal expansion coefficient and thus the zero-crossing temperature is adjusted via the titanium content. A wrong absolute titanium content leads to an incorrect value of the zero-crossing temperature and can only be compensated for to a limited extent by a suitable choice of cooling rates during annealing. An inhomogeneous distribution of the titanium leads to uneven expansion of the substrate when heated by the incident radiation. A titanium distribution inscribed in the substrate can no longer be changed in direct deposition and in the usual soot processes in which a porous glass body is deposited and then sintered.

According to the invention, it is proposed mechanically to comminute the porous glass body during the production of the titanium-doped quartz glass or to select the deposition conditions such that a powder of titanium-doped quartz glass forms directly. This powder can be analyzed and mixed from different batches to get the right titanium content. Mechanical mixing of one or more powder batches also ensures good homogeneity.

The powder may then be compressed in different ways mechanically (by uniaxial pressing into molds), by cold isostatic pressing or by floating, casting in mold or 3D printing and subsequent drying and brought into a shape corresponding to the final shape of the mirror or of the substrate for the mirror is similar. This form can then be sintered to a solid glass body while shrinking.

Also in this case, the application of the hot-isostatic pressing advantages: Since it is compacted and melted in one step, eliminates the shrinkage during sintering. By using one or more dies, this can work much closer to the final shape. Cooling channels can be inserted as a drawn and shaped tube usually made of titanium-doped quartz glass in the capsule and form a monolithic unit with the surrounding titanium-doped quartz glass. As described above, such an approach is not possible with any of the previously known methods. Likewise, cavities can be planned much more flexibly to save weight than would be possible with a conventionally produced substrate by milling or bonding.

In one embodiment, the titanium-doped quartz glass of the substrate surrounding the pipe section (and usually the material of the pipe section itself) has a temperature-dependent thermal expansion coefficient with a zero-crossing temperature in a temperature range between 20 ° C and 70 ° C, wherein a slope of the thermal Expansion coefficients of the titanium-doped quartz glass at a temperature of 22 ° C at less than 1.7 ppb / K ² , preferably less than 1.4 ppb / K ² , more preferably less than 1.0 ppb / K ² , in particular less is 0.7 ppb / K ² . Such values for the slope of the thermal expansion coefficient or the zero-crossing temperature are favorable in order to minimize temperature-induced deformations of the substrate and thus of the surface of the mirror. The titanium content of the titanium-doped quartz glass can be, for example, of the order of about 6 to 10% by weight. The material of the tube section can be drawn from the same powder mixture, with which the capsule is filled later.

In another embodiment, the titanium-doped silica glass of the substrate surrounding the pipe section has a fluorine content of between 0 ppm and 10,000 ppm by weight. By doping with fluorine, a titanium-doped quartz glass can be obtained in which the slope of the thermal expansion coefficient at a temperature of 20 ° C, for example, less than 1.0 ppb / K ² or less than 0.7 ppb / K ^{2 is} reduced, so that such a quartz glass for temperature-induced changes in length is particularly insensitive. Optionally, the quartz glass may also be doped with materials other than fluorine in order to achieve a reduction in the coefficient of thermal expansion.

In another embodiment, the zero crossing temperature in the substrate spatially varies by not more than 2.0 K, preferably not more than 1.0 K (in absolute value), to a distance of 3 cm from the surface. Typically, therefore, the fluctuation of the zero-crossing temperature around an average value in the considered volume of the substrate is not more than +/- 1.0 K, possibly not more than +/- 2.0 K, the latter especially at a low slope of the thermal expansion coefficient of less than about 1 ppb / K ^{2 is} allowed or possible. The high spatial homogeneity of the zero-crossing temperature can be achieved by the above-described thorough mixing of the powder before compression.

In the examples described above, the properties of the titanium-doped silica glass substrate outside the pipe section were described. The pipe section itself is typically also formed of titanium-doped quartz glass whose material properties should be as close as possible to the material properties of the surrounding substrate. For example, the titanium content of the pipe section should not deviate from the titanium content of the substrate material by more than +/- 5% (relative percent, i.e., no absolute variation). The fluorine content (if present) should not deviate from the fluorine content of the substrate material by more than +/- 30% (relative percent), and the OH content of the titanium-doped quartz glass, which may be loaded with hydrogen, should not exceed about +/- 10% (relative percent) differ from the OH content of the substrate material.

In another embodiment, at least one polishing layer is formed of an amorphous material between the surface of the substrate and the reflective coating. For example, at a collector mirror, a polishing layer may be interposed between the grid structure and the reflective coating to allow the reflective coating to be applied to the smooth surface of the polishing layer. It is understood that such a polishing layer can also be used in an optical element having a substrate made of another material, for example a glass ceramic.

In one embodiment, the pipe section is spaced no more than 10 mm from the surface. As described above, the pipe sections should or should be arranged as close as possible to the surface to be cooled or tempered, which can be achieved by the production described above by mechanical compaction and sintering or by hot isostatic pressing.

In a further embodiment, the pipe section has a cross-sectional area of less than 20 mm ² . As described above, due to manufacturing, the pipe sections can be produced by mechanical compacting and sintering with very small cross-sectional areas. Also is the Cross-sectional geometry almost freely selectable, wherein preferably a circular cross-sectional geometry is used, in which the tube inner diameter is favorably less than about 5 mm.

By using possibly bent pipe sections, vibrations caused by the flow of the cooling fluid, so-called "fluid-induced vibrations", FIV, can be reduced because the cooling fluid does not have to flow around corners or it is not necessary to avoid the vibrations to reduce the cooling capacity or the flow rate of the cooling fluid. It can be favorable if a turbulent flow of the cooling fluid is generated in a targeted manner, but it can also be advantageous if the cooling fluid has a laminar flow. The use of pipe sections also reduces the risk of leakage compared to conventionally made cooling channels, as the pipe sections typically have a high degree of tightness.

A further aspect of the invention relates to a lithography system, in particular an EUV lithography system, comprising: at least one optical element as described above. The optical element may be, for example, a collector mirror, a mirror of the illumination system or a mirror of the projection optics of an EUV lithography system, possibly also so-called grazing-incidence mirrors. However, it is understood that other components of a lithography system, such as a support frame for receiving mechanical forces or a support frame for holding sensors (English "sensor frame"), facet cooler or heat sink for such and other components in the manner described above monolithic can be produced.

The lithography system may include (at least) one cooling circuit connected to two ends of at least one pipe section for flowing the pipe section with a cooling fluid. The cooling circuit typically has at least one pump for this purpose. The heat absorbed by the cooling fluid is usually dissipated via one or more heat exchangers to the environment. When using a suitably dimensioned cooling circuit, it can be achieved, in particular, that the surface temperature of the optical element, in particular of a mirror for projection optics, substantially during operation of the EUV lithography system within the optically utilized area of the surface on which the EUV radiation impinges is constant, ie by no more than +/- 1.0 K, by no more than +/- 0.5 K, or by no more than +/- 0.2 K or by no more than +/- 0.1 K of deviates from a target temperature at the surface.

Such an EUV lithography system, in particular such a projection optics, makes it possible, even immediately after commissioning, i. during the heating of the optical elements to the operating temperature (i.e., in the first few minutes after the cold start) only a very small change in the aberrations of the projection optics to produce.

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

list of figures

• 1 eine schematische perspektivische Darstellung einer Kapsel mit einem in diese eingelegten Rohrabschnitt, der von einem pulverförmigen Füllmaterial umgeben wird,
• 2a eine schematische Schnittdarstellung der Kapsel von 1 in einem Ofen für einen heißisostatischen Pressvorgang,
• 2b eine schematische Darstellung analog zu 2a, bei der in die Kapsel ein Formkörper, dessen konvex gekrümmte Oberfläche an die konkav gekrümmte Oberfläche eines beim heißisostatischen Pressen hergestellten Spiegel-Substrats angepasst ist, sowie eine Verstärkungsstruktur eingebracht sind,
• 3 eine schematische Darstellung einer EUV-Lithographieanlage,
• 4 eine schematische Darstellung eines Kollektor-Spiegels für die EUV-Lithographieanlage von 3, sowie
• 5 eine schematische Darstellung eines Spiegels für ein Projektionsobjektiv der EUV-Lithographieanlage von 3.

Embodiments are illustrated in the schematic drawing and will be explained in the following description. It shows

• 1 a schematic perspective view of a capsule with a tube inserted into this, which is surrounded by a powdery filler,
• 2a a schematic sectional view of the capsule of 1 in an oven for a hot isostatic pressing process,
• 2 B a schematic representation analogous to 2a in which a molded body, the convexly curved surface of which is adapted to the concavely curved surface of a mirror substrate produced by hot isostatic pressing, and a reinforcing structure are incorporated in the capsule,
• 3 a schematic representation of an EUV lithography system,
• 4 a schematic representation of a collector mirror for the EUV lithography of 3 , such as
• 5 a schematic representation of a mirror for a projection lens of the EUV lithography of 3 ,

In the following description of the drawings, identical reference numerals are used for identical or functionally identical components.

In 1 is schematically a curved pipe section 1 shown in a cuboid capsule 2 was inserted, at the top of which an opening is formed to a powdery filler 3 in the capsule 2 fill in to the pipe section 1 with the powdery filler 3 to surround. The capsule 2 is here with the powdery filler 3 completely filled in and subsequently with a (in 1 not shown) lid closed. The capsule 2 It is typically made of a metallic material and the lid, the side walls and the bottom are welded together to form the capsule 2 complete gas-tight. The capsule 2 is designed in the manner of a can, ie deformable within certain limits. The two ends 4a . 4b , of the pipe section 1 stick out of the capsule 2 out. The openings in the capsule 2 where the two ends 4a . 4b of the pipe section 1 are guided to the outside, are sealed, eg welded or otherwise provided with a seal, so that no powdery filler 3 from the capsule 2 get outside and no gases from the outside into the capsule 2 can reach.

2a shows the capsule 2 from 1 in a heating oven or in a hot isostatic press 5 which gives a constant, high pressure on the capsule 2 and on the filling material located in this 3 exerts, so that this is compressed and at the same time due to the high temperature of several 100 ° C in the hot isostatic press 5 a melting or sintering of the capsule 2 located filling material takes place. In the hot isostatic press 5 Typically, an inert gas, such as argon, is introduced which provides the required pressure on the capsule 2 exercises.

After hot isostatic pressing, the capsule becomes 2 separated from the solidified filler. The solidified filler material forms a component which can be flowed through by a cooling fluid, since the pipe section embedded in the monolithic component 1 can flow through with a cooling fluid. The monolithic component may, for example, be a heat sink which is connected to a component to be cooled, for example via a thermal bridge, or else the component itself to be cooled or a part of the component to be cooled, in particular a substrate for one Mirror, for example, for an EUV mirror, as related to 4 and 5 will be described in more detail. In 2a is due to the sectional view only one end 4a of the pipe section 1 but it goes without saying that this is also the second end 4b of the pipe section 1 from the capsule 2 led out.

While at the in 2a As shown in the example shown, a substantially cuboidal component is produced, for example, for producing a heat sink, in the case of FIG 2 B shown example, a component in the form of a substrate 6 are generated for a mirror whose surface facing the radiation 7 has a strong concave curvature. Already at the hot isostatic pressing the geometry of the surface 7 of the substrate to be produced 6 as closely as possible, is in the capsule 2 a shaped body 8th introduced, which has a surface 9 that is due to the geometry, more specifically to the curvature of the surface 7 of the substrate 6 adjusted, ie the surface 9 of the molding 8th has a convex curvature with a radius of curvature that coincides with the concave curvature of the surface 7 of the substrate 6 matches. It is understood that even with a non-spherical, eg an elliptically curved surface 7 of the substrate 6 a surface 9 of the molding 8th can be specified with a correspondingly adapted geometry to a component, in the present case a substrate 6 to obtain whose geometry matches as well as possible with the final shape of the component to be produced. The molded body 8th does not permanently bond to the substrate 6 and is removed after hot isostatic pressing.

As in 2 B It can also be seen in the capsule 2 a reinforcing structure 17 introduced, which is plate-shaped in the example shown. At the reinforcement structure 17 is the pipe section 1 fastened by means of unillustrated brackets. By fixing to the reinforcing structure 17 is the pipe section 1 subjected to less distortion in hot isostatic pressing than without the reinforcing structure 17 the case would be. The reinforcing structure 17 is formed in the example shown from the same material as the substrate 6 , It can be prepared in a preliminary step by hot isostatic pressing or in a conventional manner, for example by casting and / or by rolling. The material of the reinforcing structure 17 combines with the hot isostatic pressing permanently with the powdery filler 3 or with the substrate 6 ,

As a powdery filler 3 In principle, all materials are considered that can be hot isostatically pressed. For example, it may be in the powdery filler 3 to act a metal powder or a ceramic powder. A glass powder, for example a quartz glass powder, especially a titanium-doped quartz glass powder, can also be used as powdered filler material 3 be used. The material of the pipe section 1 is typically applied to the powdery filler material 3 adjusted so that the thermal expansion coefficient of the material of the pipe section 1 as accurately as possible with the thermal expansion coefficient of the powdery filler 3 matches. Since the coefficient of thermal expansion of titanium-doped quartz glass (powder) and of glass ceramics is highly dependent on the thermal history and can be adjusted by tempering, it is particularly advantageous for titanium-doped quartz glass when the pipe section 1 is made of the same powder mixture as the powdery filler 3 ,

Alternatively to the in 2a capsule shown 2 in the form of a can, the capsule 2 when using a powdery filler 3 made of quartz glass also by vitrification of the surface 3a (see. 2a ) of the powdery filler 3 be formed. For this purpose, the usually precompressed powdery filler 3 by laser bombardment or by brief annealing in the hot isostatic press 5 or glazed on the surface in another oven.

3 shows very schematically an EUV lithography system in the form of an EUV lithography system 101 , can be integrated into the components that were prepared in the manner described above. The EUV lithography system 101 has an EUV light source 102 for generating EUV radiation having a high energy density in an EUV wavelength range below 50 nm, in particular between about 5 nm and about 15 nm. The EUV light source 102 For example, it may be in the form of a plasma light source for generating a laser-induced plasma or as a synchrotron radiation source. Especially in the former case, as in 3 shown is a collector mirror 103 used to monitor the EUV radiation of the EUV light source 102 to a lighting beam 104 to bundle and thus increase the energy density further. The lighting beam 104 serves to illuminate a structured object M by means of a lighting system 110 , which in the present example five reflective optical elements 112 to 116 (Mirror).

The structured object M may be, for example, a reflective mask which has reflective and non-reflective or at least less highly reflective regions for generating at least one structure on the object M. Alternatively, the structured object M may be a plurality of micromirrors which are arranged in a one-dimensional or multidimensional arrangement and which are optionally movable about at least one axis by the angle of incidence of the EUV radiation 104 to adjust to the respective mirror.

The structured object M reflects a part of the illumination beam 104 and forms a projection beam path 105 that carries the information about the structure of the structured object M and that in a projection lens 120 is irradiated, which generates an image of the structured object M or of a respective subregion thereof on a substrate W. The substrate W, for example a wafer, has a semiconductor material, for example silicon, and is arranged on a holder, which is also referred to as a wafer stage WS.

In the present example, the projection lens points 120 six reflective optical elements 121 to 126 (Mirror) to form an image of the structure on the structured object M on the wafer W. Typically, the number of mirrors is in a projection lens 120 between four and eight, but if necessary only two mirrors can be used.

As described above, components that can be flowed through with a cooling fluid can be used in different ways in the EUV lithography system 101 be used. In addition to use as a heat sink eg for the collector mirror 103 , for the mirrors 112 to 116 of the lighting system 110 or for the mirrors 121 to 126 of the projection lens 120 can also use the mirrors 103 . 112 to 116 . 121 to 126 themselves, more precisely their substrates, are formed as components through which a cooling fluid can flow, as described below with reference to FIG 4 illustrated collector mirror 103 is explained.

The collector mirror 103 has a substrate 6 on which in connection with 2 B described manner was produced by hot isostatic pressing and which is a monolithic unit with a plurality of pipe sections 1 that forms in 4 are shown in a regular arrangement, but of course in a different way in the substrate 6 can be arranged.

The collector mirror 103 has a highly reflective multilayer coating 10 with alternating single layers of silicon and molybdenum on to EUV radiation 11 at a useful wavelength in the range of about 13.5 nm. Depending on the useful wavelength used, other material combinations such as molybdenum and beryllium, ruthenium and beryllium or lanthanum and B ₄ C are also possible as layer materials. The reflective multi-layer coating 10 has a cover layer (not shown), which may be formed of a metal, eg of ruthenium, or of a metal oxide.

On the concavely curved surface 7 of the substrate, which may, for example, form a section of an ellipsoid of revolution or of a paraboloid of revolution to that of the EUV light source 102 (see. 3 ) outgoing EUV radiation 11 to bundle is at the in 4 shown example, a metallic layer 12 made of silver, which helps to improve the hydrogen resistance of the substrate 6 can serve, and optionally without adhesion promoter on the material of the substrate 6 adheres, for example, when the substrate 6 is formed of SiSiC. In the metallic layer 12 is a lattice structure in the form of a diffraction grating 13 formed, which serves, from the EUV light source 102 outgoing IR radiation 14 , which may for example have a wavelength of about 10.6 microns, to scatter in higher diffraction orders, so that the smallest possible proportion of the IR radiation 14 at the collector mirror 103 is reflected and over the illumination beam 104 in the lighting system 110 is irradiated.

Between the surface 7 of the substrate 6 and the reflective coating 10 is at the in 4 example shown a polishing layer 15 formed from amorphous silicon, which also serves as a primer layer. Alternatively, the polishing layer 15 have another amorphous material which can be processed by means of a polish, for example a material which is selected from the group: amorphous silicon monoxide, amorphous silicon dioxide or nickel, cf. also the DE 10 2009 039 400 A1 , The polishing layer 15 allows the roughness caused by the graininess of the material of the lattice structure 13 and caused by the machining process while preserving the lattice structure 13 to reduce. Other than this in 4 is simplified, the reflective coating 10 on the smooth top of the polishing layer 15 while preserving the lattice structure 13 applied. Optionally, the polishing layer 15 and / or on the metallic layer 12 be waived. In the latter case, the grid structure becomes 13 or the diffraction grating directly at the top 7 of the substrate 6 formed. Alternatively, the grid structure 13 are also impressed in the hot isostatic pressing, if a molding 8th with one of the grid structure 13 corresponding or complementary to this structure in the capsule 2 is inserted, which is later removed, for example, etched away.

At the in 4 Example shown are in the monolithic substrate 6 several pipe sections 1 made of copper. The substrate 6 itself is formed from dispersion-hardened copper containing nanoparticles of Al ₂ O ₃ and, for example, under the trade name Glidcop® AL 15 or AL- 25 is offered. The coefficient of thermal expansion of Glidcop® is similar to that of pure copper, this material has more than about 92% of the thermal conductivity of pure copper. Advantageous is the use of the variant Glidcop® LOX, since this material is resistant to hydrogen embrittlement. The substrate 6 may alternatively be formed from another metallic material or from a ceramic, for example from SiSiC, wherein SiSiC has a significantly lower thermal conductivity than (dispersion-hardened) copper, which makes the heat removal more difficult.

At the in 4 The example shown is the monolithic substrate 6 Part of a body 16 of the collector mirror 103 that also has a reinforcing structure 17 has, in the example shown consists of a rolled copper alloy, which may also be Glidcop®. The use of a reinforcing structure 17 From a rolled copper alloy offers the advantage that it has the same or a similar coefficient of thermal expansion as the substrate 6 , so that only small deformations result from temperature changes. The reinforcing structure 17 can in a basically arbitrary way with the substrate 6 , more precisely with its back 18 be connected, for example, by soldering, welding, gluing, screwing or riveting.

As in 4 can also be seen, have the pipe sections 1 a comparatively small cross-sectional area Q of less than about 20 mm ² , ie the diameter of the pipe sections 1 is a little less than about 5 mm. The centers of the pipe sections 1 are at the in 4 shown example at a constant distance A1 from the surface 7 of the substrate 6 arranged, where A1 = 3 mm applies. The smallest possible distance A1 of the pipe sections 1 from the surface 7 has proven to be favorable, with the pipe sections 1 with a part of its pipe wall to less than the distance A1 of 3 mm to the surface 7 come close.

The pipe sections 1 are at the in 4 shown by no more than a distance A2 of 10 mm from the surface 7 of the substrate 6 spaced. As described above, it is beneficial if the pipe sections 1 as close as possible to the surface to be cooled 7 reach to allow effective cooling. The monolithic substrate 6 itself extends in the example shown over a distance A3 of about 3 cm from the surface 7 out. The substrate 6 has a slightly greater thickness in its edge region than in the middle to a flat back 18 to form and in this way the attachment to the rolled reinforcing structure 17 to simplify. To reduce the mass of the collector mirror 103 may have blind holes or ribs on the back 18 of the substrate 6 and optionally attached to its peripheral side wall, for example, by milling or erosion after the hot isostatic pressing or by the use of a suitable shaped body before the hot isostatic pressing into the capsule 2 is inserted, or by a reinforcing structure 17 in the form of a hollow body, which connects to the outside of the capsule 2 and that is permanently attached to the substrate 6 connects, into the capsule 2 is inserted.

As in 4 and also in 2 B is indicated on the inside 1a the pipe sections 1 made of copper a lining 19 attached, which consists of a metallic material, in the example shown of aluminum. Alternatively, on the inside 1a of the pipe section 1 another metallic material or (after the hot isostatic pressing) a plastic coating or a liner made of a plastic tube may be attached. Alternatively, as a lining on the inside 1a the pipe sections 1 - Typically, before hot isostatic pressing - pipes made of stainless steel or aluminum are introduced. To avoid getting these tubes in case of temperature changes of the substrate 6 lead to tensions, thin, possibly corrugated pipes can be used.

5 shows by way of example the first EUV level 121 of the projection system 120 , which is also a substrate 6 which has been produced by mechanical compacting and sintering. The substrate 6 is at the in 5 formed example of titanium-doped quartz glass, wherein the titanium content is about 7%. For the preparation of the substrate 6 a titanium-doped quartz glass powder was used. In the production of the quartz glass powder by direct deposition, the quartz glass powder is produced by crushing a porous, solid glass body. In the production of the quartz glass powder in a soot process, in the event that the flame is not aimed at a target but burns in a large chamber, directly on the walls of the chamber immediately loose quartz glass powder can be deposited, which only from the walls of the Chamber must be swept.

The quartz glass powder was analyzed for its composition, particularly in terms of its Ti content, and batches each having different Ti content were formed. As a powdery filler for the production of the substrate 6 Quartz glass powders used were then mixed together from different batches to set the desired titanium content. A mechanical mixing of one or more powder lots ensures good homogeneity of the substrate obtained from the quartz glass powder 6 ,

At the in 5 The example shown has the substrate 6 (outside the pipe sections 1 ) a temperature-dependent coefficient of thermal expansion CTE with a zero-crossing temperature Tzc in a temperature range between 20 ° C and 70 ° C, wherein a slope .DELTA.CTE / .DELTA.T of the thermal expansion coefficient CTE of the titanium-doped quartz glass at a temperature of 22 ° C at less than 1, 7 ppb / K ² , favorably less than 1.4 ppb / K ² , in particular less than 1.0 ppb / K ² , ideally less than 0.7 ppb / K ² . Particularly small values of the slope of the thermal expansion coefficient ΔCTE / ΔT of the titanium-doped quartz glass of typically less than about 1.0 ppb / K ² can be obtained if the quartz glass is additionally doped with fluorine. The fluorine content of the quartz glass of the substrate 6 For example, it may be between 0 ppm and 10,000 ppm by weight.

By the possibility of mixing the quartz glass powder before the production of the substrate 6 By mechanical compaction and sintering, the titanium content can be adjusted very accurately, so that the zero-crossing temperature Tzc in the substrate 6 up to a distance A3 of 3 cm from the surface 7 spatially by not more than +/- 2.0 K, preferably by not more than +/- 1.0 K, varies.

At the in 5 Example shown are the pipe sections 1 likewise formed from titanium-doped quartz glass whose properties, for example its titanium content, are as good as possible with the properties of the titanium-doped quartz glass of the substrate 6 outside the pipe sections 1 should match. The pipe sections 1 Of titanium-doped quartz glass may be formed, for example, as drawn and shaped tubes. The titanium content of the pipe sections 1 should not exceed +/- 5% of the titanium content of the Differ substrate material. The fluorine content (if any) should not exceed +/- 30% of the fluorine content of the substrate 6 differ and also the OH content of the typically loaded with hydrogen titanium-doped quartz glass of the pipe sections 1 should not exceed about +/- 10% of the OH content of the substrate 6 differ.

At the in 5 The example shown is the main body of the mirror 121 only from the monolithic substrate 6 , It is understood that similar to above related 4 the substrate was described 6 can be connected to a reinforcing structure of a suitable material for this purpose.

Although it has proved to be favorable, the quartz glass substrate 6 with the aid of the above-described hot isostatic pressing, but it is alternatively possible, the substrate 6 by means of a method in which compacting and sintering take place in two successive steps. For example, the uniaxial pressing, cold isostatic pressing, flooding, casting in the mold or 3D printing and subsequent drying, the quartz glass powder can be brought into a shape corresponding to the final shape of the substrate 6 similar. This form can then be sintered to a solid glass body while shrinking.

During operation of the EUV lithography system 101 , possibly even during breaks, is through the pipe sections 1 a cooling fluid 20 directed, like this in 5 is indicated. In the cooling fluid 20 it may, for example, be water or another suitable cooling fluid. The cooling fluid 20 can the respective pipe section 1 over an end 4a fed and at the other end 4b of the pipe section 1 be dissipated. For this purpose, the ends 4a . 4b the pipe sections 1 For example, be connected to directly soldered or welded metallic bellows or flanges. At the ends 4a . 4b the pipe sections 1 It is also possible to form flat milled sealing surfaces, to which flanges can be flanged using O-rings.

It is understood that other components of the EUV lithography system 101 with a monolithic substrate 6 be equipped or provided with a monolithic heat sink, which was prepared in the manner described above. These components may be, for example, support frames for receiving mechanical forces or for holding sensors, facet coolers, grazing-incidence mirrors, etc.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009039400 A1 [0005, 0072]
• DE 102015210045 A1 [0006]

Claims (22)

Method for producing a component (6) for a lithography system (101) through which a cooling fluid (20) can flow, comprising the steps: Surrounding a tube section (1) arranged inside a capsule (2) and permeable by the cooling fluid (20) with a powdery filling material (3), wherein at least one end (4a, 4b) of the pipe section (1) protrudes from the capsule (2), and Producing the component (6) by hot isostatic pressing of the powdery filling material (3) arranged in the capsule (2). Method according to Claim 1 in which before the hot isostatic pressing in the capsule (2) a shaped body (8) is inserted, which has at least one surface (9) which is adapted to the geometry of a surface (7) of the component (6) to be produced, wherein the Surface (9) of the shaped body (8) is preferably concave or convex curved. Method according to Claim 1 or 2 in which prior to the hot isostatic pressing in the capsule (2) a reinforcing structure (17) is inserted, which connects in the hot isostatic pressing with the powdery filling material (3). Method according to one of the preceding claims, wherein the pipe section (1) with a powdery filler (3) in the form of a metal powder, preferably a dispersion-hardened copper powder, aluminum powder or in the form of a ceramic powder is surrounded, wherein the pipe section (1) preferably from a metallic Material, in particular made of copper, aluminum, or stainless steel is formed. Method according to one of the preceding claims, in which the tube section (1) is surrounded by a powdery filling material (3) in the form of glass powder, preferably in the form of in particular titanium-doped quartz glass powder, and in which the tube section (1) consists of glass, preferably of in particular titanium-doped quartz glass. Method according to one of the preceding claims, in which the capsule (2) is formed by vitrifying the surface (3a) of the powdery filling material (3). An optical element (103) for reflecting radiation (11), comprising: a base body (16) having a substrate (6) having a surface (7) to which a reflective coating (10) is applied, the substrate ( 6) has at least one pipe section (1) through which a cooling fluid (20) can flow, characterized in that the substrate (6) is produced by mechanical compacting and sintering, in particular by hot isostatic pressing, and in that the pipe section (1) up to a distance (A1) of less than 5 mm, preferably less than 3 mm, to the surface (7) extends. Optical element after Claim 7 in which the substrate (6) is made of dispersion-hardened copper or of a ceramic. Optical element according to one of Claims 7 or 8th in which a lining (19) of metal and / or plastic is attached to the inside (1a) of the pipe section (1). Optical element according to one of Claims 7 to 9 in which the substrate (6) extends at least 3 cm from the surface (7). Optical element according to one of Claims 7 to 10 , which is designed as a collector mirror (101) for bundling EUV radiation (11). Optical element after Claim 11 in which a grating structure (13) for diffracting IR radiation (14) is provided on the surface (7) of the substrate (6) or on a metallic layer (12) mounted between the substrate (6) and the reflective coating (10). is formed. Optical element according to one of Claims 7 to 12 in which the base body (16) has a reinforcing structure (17) of a preferably metallic material attached to the substrate (6) or with the substrate (6) by mechanical compression and sintering, in particular by hot isostatic pressing, is connected. Optical element according to one of Claims 7 to 13 in which the substrate (6) has a porosity of less than 1%, preferably less than 0.1%, in particular less than 0.01%. Optical element (121) according to the preamble of Claim 7 , especially after one of Claims 7 to 14 , characterized in that the substrate (6) by mechanical compression and sintering, in particular by hot isostatic pressing, and is made of glass, preferably made of particular titanoted quartz glass, wherein the at least one with the cooling fluid (20) through-flow pipe section (1 ) is preferably made of glass, particularly preferably of titanium-doped quartz glass. Optical element after Claim 15 in which the titanium-doped quartz glass of the substrate (6) surrounding the pipe section (1) has a temperature-dependent thermal expansion coefficient (CTE) with a zero-crossing temperature (Tzc) in a temperature range between 20 ° C and 70 ° C, wherein a slope (ΔCTE / .DELTA.T) of the thermal expansion coefficient (CTE) of the titanium-doped quartz glass at a temperature of 22 ° C at less than 1.7 ppb / K ² , preferably less than 1.4 ppb / K ² , more preferably less than 1.0 ppb / K ² , in particular at less than 0.7 ppb / K ² . Optical element after Claim 16 in which the titanium-doped quartz glass of the substrate (6) surrounding the pipe section (1) has a fluorine content between 0 ppm and 10000 ppm by weight. Optical element after Claim 16 or 17 in which the zero-crossing temperature (Tzc) in the substrate (6) is spatially not more than +/- 2.0 K up to a distance of 3 cm from the surface (7), preferably not more than +/- 1.0 K varies. Optical element according to one of Claims 7 to 18 in which at least one polishing layer (15) of an amorphous material is formed between the surface (7) of the substrate (6) and the reflective coating (10). Optical element according to one of Claims 7 to 19 in which the pipe section (1) is spaced no more than 10 mm from the surface (7). Optical element according to one of Claims 7 to 20 in which the pipe section (1) has a cross-sectional area (Q) of less than 20 mm ² . Lithography system, in particular EUV lithography system (101), comprising: at least one optical element (102, 121) according to one of Claims 7 to 21 ,

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