Method for producing a cooling element, cooling element for optical arrangements and optical arrangements for microlithography comprising a cooling element

Abstract

The present invention relates to a method for producing a cooling element (11) for an optical arrangement, in particular for an optical arrangement for microlithography, in which a heat sink (12) having at least one cooling channel (16) having at least one inlet and at least one outlet (14) for a cooling medium that can flow through the at least one cooling channel (16) is formed preferably by joining, in particular soldering and / or welding, and / or by an additive manufacturing method with layer-by-layer deposition of material, wherein each deposited layer is formed according to an associated cross-section of the heat sink (12) and wherein after the heat sink (12) has been formed, a corrosion-resistant coating is produced in the at least one cooling channel (16) by atomic layer deposition. The invention also relates to a corresponding cooling element (11) and to an optical arrangement comprising a corresponding cooling element (11), and to the operation thereof.

Description

[0001] Method for producing a cooling element, cooling element for optical arrangements, and optical arrangements for microlithography with a cooling element

[0002] BACKGROUND OF THE INVENTION

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a method for producing a cooling element for an optical arrangement, in particular for an optical arrangement for microlithography, as well as a corresponding cooling element and an optical arrangement with a corresponding cooling element and their operation.

[0005] STATE OF THE ART

[0006] For the production of micro- or nanostructured components in microsystems technology or microelectronics, microlithographic processes are known. These processes involve projection exposure systems for imaging the micro- or nanostructures to be produced, miniaturizing the structures on a reticle or mask onto a light-sensitive layer. Due to the increasing miniaturization of the structures to be produced, projection exposure systems are now being used for this purpose. These systems operate with working light with increasingly shorter wavelengths, for example, in the extreme ultraviolet (EUV) wavelength range. However, such EUV light leads to significant heating of optical elements, such as mirrors, in the projection exposure system, which require appropriate cooling.Appropriate cooling elements can be provided for this purpose, but due to the limited space available, they must be dimensioned correspondingly small. For example, cooling elements with internal cooling channels for the passage of cooling media are used to dissipate heat. With a diameter of less than or equal to 5 mm, the cooling channels are usually small in terms of diameter, while the length of the cooling channels can easily reach lengths of more than 200 or 400 mm. With such cooling elements, the production of correspondingly fine cooling channel structures and ensuring the longest possible service life presents a challenge.

[0007] Passivation coatings for microchannel coolers are known from the publication by Richard W. Bonner III, Jens Weyant, Evan Fleming, Kevin Lu, Daniel Reist from Advanced Cooling Technologies, Inc. Lancaster, Pa, USA (https: / / www.1-act.com / passivation-coatings-for-micro-channel-coolers / ).

[0008] DISCLOSURE OF THE INVENTION

[0009] OBJECT OF THE INVENTION

[0010] It is therefore an object of the present invention to provide a cooling element and a manufacturing method for a corresponding cooling element that is suitable for use in optical arrangements for microlithography, whereby correspondingly fine cooling channel structures must be realized. Furthermore, the longest possible service life and safe, effective, and efficient operation should be ensured.

[0011] TECHNICAL SOLUTION

[0012] This object is achieved by a manufacturing method having the features of claim 1 and a cooling element having the features of claim 13. Furthermore, the invention proposes a method for operating an optical arrangement having the features of claim 17 and an optical arrangement having the features of claim 19. Advantageous embodiments are the subject of the dependent claims.

[0013] The present invention proposes, for the production of a cooling element for an optical arrangement, in particular for an optical arrangement for microlithography, to ensure a long service life of the cooling element and reliable operation, to provide or form a heat sink with at least one cooling channel through which a cooling medium can be passed for heat dissipation, so that efficient cooling of components of the optical arrangement can be ensured, and to produce a corrosion-resistant coating in the at least one cooling channel by atomic layer deposition, so that corrosion problems that can be caused by the cooling medium flowing through the at least one cooling channel are avoided. The atomic layer deposition ensures that the entire cooling channel can be coated despite a large length in relation to a small diameter and thus an unfavorable aspect ratio.

[0014] To form the heat sink, subcomponents can be joined, in particular soldered and / or welded, and / or a generative or additive manufacturing process can be used, with which a heat sink with at least one cooling channel with a small diameter and a large length can be easily produced. The generative manufacturing process with layer-by-layer deposition of material allows any desired shape to be formed, since each deposited layer can be formed according to a corresponding cross-section of the heat sink.

[0015] In additive manufacturing, the heat sink can be built layer by layer on a substrate or a previously produced heat sink part. This layer-by-layer buildup is achieved by layer-by-layer deposition welding or by melting powder material layer by layer with a high-energy beam and allowing the powder melt to solidify layer by layer. The high-energy beam can be a laser or electron beam.

[0016] The heat sink can be made of steel, preferably stainless steel, in particular a high-alloy chromium-nickel steel, preferably X2CrNiMo17-12-2.

[0017] Additionally or alternatively, copper and / or aluminum materials can be used, such as technically pure copper or aluminum or alloys thereof.

[0018] For brazing subcomponents, brazing alloys, in particular brazing alloys for steels or copper or aluminum materials, preferably Ni-based brazing alloys such as Ni 620 according to ISO 17672 can be used, whereby the brazing alloy Ni 620 according to ISO 17672 corresponds to the brazing alloy B-Ni82CrSiBFe-970 / 1000 according to ISO 3677 or the brazing alloy BNi-2 according to ANSI (American National Standards Institute) / AWS (American Welding Society) Standard A5.8 and has a composition of 7 wt.% Cr, 4.5 wt.% Si, 3.1 wt.% boron, 3 wt.% iron and the remainder Ni and unavoidable impurities.

[0019] The corrosion-resistant coating may comprise at least one component from the group consisting of Al2O3, AlN, TiN, AlTiN, ZrO2, HfO2 and SiO2.

[0020] Before the atomic layer deposition, the surface of the at least one cooling channel can be functionalized with hydroxyl groups, in particular by a self-assembling monolayer with a thiol alcohol, in order to facilitate or enable the subsequent atomic layer deposition with trimethyl aluminum AI(CHs)3.

[0021] Accordingly, for atomic layer deposition, in a first step, trimethyl aluminum AI(CHs)3 can be bound to hydroxyl groups on the surface of at least one cooling channel with the release of methane, wherein in a second step, water can react with the remaining methyl groups to form methane to form aluminum oxide.

[0022] Alternatively, for atomic layer deposition, in a first step, trimethylaluminum AI(CHS)3 and titanium chloride TiCh can be bound to hydroxyl groups on the surface of at least one cooling channel, releasing methane and hydrochloric acid. In a second step, ammonia can react with the remaining methyl groups and titanium trichloride to form methane and hydrochloric acid, thus forming titanium aluminum nitride. Another possibility for atomic layer deposition is to bind tris(butylcyclopentadienyl)yttrium to hydroxyl groups on the surface of at least one cooling channel, releasing (butylcyclopentadienyl) hydrogen. In a second step, water can react with the remaining (butylcyclopentadienyl)yttrium to form (butylcyclopentadienyl) hydrogen, thus forming yttrium oxide.

[0023] Further coatings and reaction systems for producing them are possible and are detailed in the description of exemplary embodiments. Between the first reaction step, with the bonding of, for example, trimethylaluminum AI(CHs)3 and / or titanium chloride TiCk and / or tris(butylcyclopentadienyl)yttrium to the hydroxyl groups on the surface of the cooling channel, and the second reaction step, with the reaction of, for example, water or steam and / or ammonia with the remaining methyl groups and / or titanium trichloride and / or (butylcyclopentadienyl)yttrium, a cleaning step by flushing with an inert gas can be carried out.

[0024] A cycle consisting of the first reaction step and the second reaction step with or without a cleaning step can be repeated several times until the desired layer thickness is reached, which can be in the range of 10 nm to 500 nm.

[0025] Accordingly, a cooling element for an optical arrangement, in particular for an optical arrangement for microlithography, is also claimed, which can preferably be manufactured according to the method described above. The cooling element accordingly comprises a heat sink with at least one cooling channel, which has at least one inlet and at least one outlet for a cooling medium that can flow through the at least one cooling channel, wherein a corrosion-resistant coating is arranged in the at least one cooling channel.

[0026] The heat sink can be formed by joining, in particular soldering and / or welding, subcomponents and / or by a generative manufacturing process by depositing material layers.

[0027] The corrosion-resistant coating can in turn be formed by Al2O3, AlN, TiN, AlTiN, ZrO2, HfO2 and SiO2 or combinations thereof.

[0028] The heat sink can be cuboid-shaped or have any other desired shape. Preferably, the heat sink has a plurality of meandering cooling channels arranged one above the other, preferably in several planes, wherein, in particular, the at least one cooling channel can branch into a plurality of cooling channels.

[0029] The at least one cooling channel can have a length of more than 100 mm, in particular more than 400 mm, and a diameter of less than or equal to 10 mm, in particular less than or equal to 5 mm, preferably less than or equal to 3 mm. The cooling element can be operated such that demineralized water is passed through the cooling channel to absorb heat.

[0030] The optical arrangement in which a corresponding cooling element can be used can be a projection exposure system or mask inspection device.

[0031] BRIEF DESCRIPTION OF THE CHARACTERS

[0032] The attached drawings show in a purely schematic manner in

[0033] Figure 1 is a schematic representation of a device for the generative production of cooling elements using the example of selective laser melting,

[0034] Figure 2 is a perspective view of a generatively manufactured cooling element,

[0035] Figure 3 is a sectional view through the cooling element of Fig. 2,

[0036] Figure 4 is a flow diagram for the atomic layer deposition of a corrosion protection layer in the cooling channels of the cooling element from Fig. 2 and 3 and in

[0037] Figure 5 shows an illustration of an EUV projection exposure system.

[0038] EXAMPLES OF IMPLEMENTATION

[0039] Further advantages, characteristics, and features of the present invention will become apparent from the following detailed description of the embodiments. However, the invention is not limited to these embodiments.

[0040] Figure 1 shows a purely schematic representation of a device 1 such as can be used, for example, for selective laser melting for the generative production of a cooling element 11. The device 1 comprises a lifting table 2, on the platform of which a semi-finished product 3 is arranged, onto which material is deposited layer by layer in order to produce a three-dimensional component in the form of a cooling element 11 for a projection exposure system. For this purpose, powder 7, which is located above a lifting table 9 in a powder reservoir, is pushed layer by layer over the semi-finished product 3 by means of a slider 8 and then bonded to the already existing semi-finished product 3 by a laser beam 5 of a laser 4 by melting.The powder material in a powder layer is bonded to the semi-finished product 3 by the laser 4 depending on the desired contour of the cooling element 11 to be produced, so that any three-dimensional shapes and in particular cavities, such as cooling channels 16, can be created. Accordingly, the laser beam 5 is guided over a powder bed 6 in order to melt powder material through different impact points on the powder bed 6 according to the contour of the three-dimensional cooling element 11 in the sectional plane corresponding to the layer plane created, and to bond it to the already produced part of the semi-finished product 3 or to an initially provided substrate. The laser beam 5 can be guided over the surface of the powder bed 6 by a suitable deflection unit, and / or the powder bed 6 can be moved relative to the laser beam 5.

[0041] To avoid undesirable reactions with the ambient atmosphere during melting or sintering, the process can take place in a closed space provided by a housing 11 of the device 1. An inert gas atmosphere can also be provided, for example, to prevent oxidation of the powder material and the like during deposition. Nitrogen or argon, for example, can be used as the inert gas, which is provided via a gas supply (not shown).

[0042] Instead of the inert gas, another process gas could also be used if, for example, reactive deposition of the powder material is desired.

[0043] In addition, other types of radiation are also conceivable, such as electron beams or other particle beams or light beams used in stereolithography.

[0044] Figure 2 shows a perspective view of a cooling element 11, which can be manufactured using a device 1 according to Figure 1 by generative or additive manufacturing. Alternatively, production by joining, in particular soldering and / or welding, preferably diffusion welding of subcomponents is also possible, for example by manufacturing parts of the heat sink 12 separately, for example also by additive manufacturing, and then connecting them to one another by soldering or welding.

[0045] The cooling element 11 has a heat sink 12, in which, on the one hand, openings 15 for increasing the surface area are arranged, and, on the other hand, internal cooling channels 16 (see Figure 3) through which a cooling medium, such as demineralized water, so-called deionized water (VE water), can be passed. For this purpose, an inlet 13 and an outlet 14 are provided on the cooling element 11. These inlets are connected to the cooling channels 16 to allow the cooling medium to be introduced and discharged from the cooling element 11.

[0046] Figure 3 shows a section through the cooling element 11 from Figure 2, parallel to the main surface or top side, which is spanned by the sides of the cooling element 11 with the largest dimensions, i.e. the long side and the wide side. In the sectional view of Figure 3, it can be seen that a plurality of cooling channels 16, which have a meandering shape, are connected to the outlet 14. Figure 3 shows one plane of the cooling channels 16, wherein in the cooling element 11 of Figures 2 and 3, two planes with cooling channels 16 are arranged one above the other, which are connected to one another via vertical sections of the cooling channels 16 (in the left-hand part of the image in Figure 3), so that the cooling medium flows once along the long side and back again in the other plane.

[0047] According to the invention, the cooling channels 16 of the additively manufactured cooling element 11, which is formed, for example, from stainless steel, are provided with a corrosion protection coating that prevents corrosion of the cooling channels 16 by demineralized water. In the illustrated embodiment, for example, a corrosion protection layer made of aluminum oxide can be formed by atomic layer deposition.

[0048] Figure 4 shows the process steps for forming a corrosion protection layer in the cooling channels 16 of the cooling element 11 in a flowchart. In a first functionalization step 20, hydroxyl groups are provided on the surface of the cooling channels 16 by passing thiol alcohol through them, forming a self-organizing monolayer of thiol alcohol on the surface of the cooling channels 16 to provide the required hydroxyl groups.

[0049] In a first reaction step 21, the hydroxyl groups provided on the surface of the cooling channels 16 react with trimethylaluminium AI(CH3)3. The OH groups form active binding sites for the metal ligand molecule trimethylaluminium AI(CH3)3, resulting in the following reaction (1 ):

[0050] -OH + AI(CH3)3 ^ (O)AI(CH3)2 + CH4 (1 )

[0051] At the end of this reaction, the methane (CH4) is removed via an inert gas purge in a purification step 22 and the remaining Al(CHs)2 provides the necessary surface chemistry for the next reaction.

[0052] In the second reaction step 23, water vapor (H2O) is introduced into the cooling channel and triggers the following reaction (2):

[0053] 2 (O)AI(CH3)2+ 4 H2O 2 AI(OH)(O)3 / 2 +4 CH4+ H2O (2)

[0054] In this reaction, the H2O reacts with the -CH3- sites remaining from the original precursor. The reaction saturates once all -CH3- sites have reacted. At the end of this reaction, a single cycle of atomic layer deposition is completed, and the hydroxyl group density at the surface is restored to the state after the functionalization step 20. Accordingly, the cycle consisting of the first reaction step 21, optional purification step 22, and second reaction step 23 can be repeated until a sufficient thickness of the corrosion protection layer in the range of 10 to 500 nm is achieved.

[0055] Other coatings considered include coatings made of AlN, TiN, TiAlN, ZrO2, HfO2, Y2O3, and SiO2. For the atomic layer deposition of aluminum nitride (AlN), the following reactions can be used: in the first reaction step 21, the hydroxyl groups provided on the surface of the cooling channels 16 can react with trimethylaluminum Al(CHS)3 according to (1 a), while in the second reaction step 23, for example, NH3 gas (see (2a)) or N2 / H2 plasma or hydrazine (N2H4) can be used instead of H2O.

[0056] -OH + AI(CH3)3 -O-AI(CH3)2+ CH4 (1 a)

[0057] -O-AI(CH3)2 + NH3 = -O-AI(NH) + 2 CH4(2a):

[0058] For the atomic layer deposition of aluminum nitride (TiN), the following reactions can be used, whereby in the first reaction step 21 the hydroxyl groups provided on the surface of the cooling channels 16 can react using titanium tetrachloride (TiCk) according to (1 b), while in the second reaction step 23, for example, NHs gas see (2b) or N2 / H2 plasma or hydrazine (N2H4) can be used instead of H2O.

[0059] -OH + TiCl4= -O-Ti(CI)3+ HCl (1 b)

[0060] -O-Ti(CI)3+ NH3 = -O-Ti(N) + 3 HCl (2b)

[0061] The following reactions can be used for the atomic layer deposition of titanium aluminum nitride (TiAlN). In the first reaction step 21, the hydroxyl groups provided on the surface of the cooling channels 16 can react with trimethylaluminum Al(CH3)3 and titanium tetrachloride (TiCl) according to (1 c), while in the second reaction step 23, e.g., NH3 gas can be used (see (2 c). -(OH)2 + Al(CH3)3 + TiCl = -O-Al(CH3)2 + -O-Ti(Cl)3 + CH4 + HCl (1 c)

[0062] -O-AI(CH3)2 + -O-Ti(CI)3 + 2 NH3 = (-O-)2(Al, Ti)(N)(NH) + 2 CH4+ 3 HCl (2c)

[0063] For the atomic layer deposition of zirconium oxide (ZrO2), the following reactions can be used, whereby in the first reaction step 21 the hydroxyl groups provided on the surface of the cooling channels 16 can react by means of zirconium tetrachloride (ZrCl4) according to (1d), while in the second reaction step 23 water or steam (2d) can be used.

[0064] -OH + ZrCl4= -O-Zr(CI)3+ HCl (1 d)

[0065] -O-Zr(CI)3+ 2H2O = -O-Zr(OH)(O) + 3HCl (2d)

[0066] For the atomic layer deposition of hafnium oxide (HfO2), the following reactions can be used, whereby in the first reaction step 21 the hydroxyl groups provided on the surface of the cooling channels 16 can react by means of hafnium tetrachloride (HfCl4) or tetrakis(dimethylamino)hafnium (TDMAH) according to (1 e), while in the second reaction step 23 water or steam (2e) can be used.

[0067] -OH + HfCk = -O-Hf(CI)3+ HCl (1 e)

[0068] -O-Hf(CI)3+ 2 H2O = -O-Hf(OH)(O) + 3 HCI For the atomic layer deposition of yttrium oxide (Y2O3), the following reactions can be used, whereby in the first reaction step 21 the hydroxyl groups provided on the surface of the cooling channels 16 can react by means of tris(butylcyclopentadienyl) - yttrium (Y(C5H4CH2(CH2)2CH3)3, abbreviated as YCpBut, CpBut corresponds to (C5H4CH2(CH2)2CH3)) according to (1f), while in the second reaction step 23 water or steam (2f) can be used.

[0069] -OH + Y(CpBut)3= -OY(CpBut)2+ HCpBut (1 f)

[0070] -OY(CpBut)2+ 3 / 2 H2O = -OY(OH)(O)I / 2+ 2 HCpBut (2f)

[0071] For the atomic layer deposition of silicon oxide (SiO2), the following reactions can be used, wherein in the first reaction step 21 the hydroxyl groups provided on the surface of the cooling channels 16 can react by means of Si(C2HsO)4 (TEOS) or SiCk or Si(NCO)4 according to (1 g), while in the second reaction step 23 water or water vapor (2 g) can be used.

[0072] -OH + SiCl4= -O-SiC + HCl (1 g)

[0073] -O-SiCh + 2 H2O = -O-Si(OH)(O) + 3 HCl (2 g)

[0074] Figure 5 shows a purely schematic representation of an EUV projection exposure system 25 that is operated with working light in the wavelength spectrum of extreme ultraviolet light (EUV light). The projection exposure system 25 has an illumination source 26, an illumination system 27, and a projection lens 28, with the aid of which the structures provided on a reticle 29 are imaged in a reduced manner onto a wafer 30 in order to produce micro- or nanostructures there via microlithographic processes. Components of the EUV projection exposure system 25, such as mirrors or the like, can become considerably heated by the EUV radiation, necessitating cooling. For this purpose, cooling elements 11 can be used, such as those shown, for example, in Figures 2 and 3 and described above.

[0075] Although the present invention has been described in detail with reference to the exemplary embodiments, it will be understood by those skilled in the art that the invention is not limited to these exemplary embodiments, but rather that modifications are possible in such a way that individual features can be omitted or other combinations of features can be implemented without departing from the scope of the appended claims. In particular, the present disclosure includes all combinations of the individual features shown in the various exemplary embodiments, so that individual features that are described only in connection with one exemplary embodiment can also be used in other exemplary embodiments or in combinations of individual features not explicitly shown.

[0076] LIST OF REFERENCE SYMBOLS

[0077] 1 device

[0078] 2 lifting tables

[0079] 3 Semi-finished product or manufactured component

[0080] 4 lasers

[0081] 5 Laser beam

[0082] 6 powder bed

[0083] 7 powders

[0084] 8 sliders

[0085] 9 lifting table

[0086] 10 housings

[0087] 11 Cooling element

[0088] 12 heat sinks

[0089] 13 Entrance

[0090] 14 Outlet

[0091] 15 Opening

[0092] 16 cooling channel

[0093] 20 functionalization step

[0094] 21 first reaction step

[0095] 22 cleaning steps

[0096] 23 second reaction step

[0097] 25 projection exposure system

[0098] 26 Lighting source

[0099] 27 Lighting system

[0100] 28 Projection lens

[0101] 29 reticles

[0102] 30 wafers

Claims

PATENT CLAIMS 1 . Method for producing a cooling element (11) for an optical arrangement (25), in particular for an optical arrangement for microlithography, in which a heat sink (12) with at least one cooling channel (16) with at least one inlet (13) and at least one outlet (14) for a cooling medium which can flow through the at least one cooling channel (16) is provided or formed, wherein a corrosion-resistant coating is produced in the at least one cooling channel (16) by atomic layer deposition, wherein the corrosion-resistant coating has at least one component from the group comprising Al2O3, AlN, TiN, AlTiN, ZrO2, HfC and SiO2.

2. Method according to claim 1, characterized in that the heat sink is formed by joining, in particular soldering and / or welding, subcomponents and / or by a generative manufacturing process with layer-by-layer deposition of material, each deposited layer being formed in accordance with an associated cross-section of the heat sink (12).

3. The method according to claim 1 or 2, characterized in that before the atomic layer deposition, the surface of the at least one cooling channel is functionalized with hydroxyl groups, in particular by a self-organizing monolayer with a thiol alcohol.

4. Method according to one of the preceding claims, characterized in that for the atomic layer deposition, in a first step, trimethyl aluminum AI(CHS)3 is bound to hydroxyl groups on the surface of the at least one cooling channel with the release of methane, wherein in a second step, water reacts with the remaining methyl groups to form methane in order to form aluminum oxide.

5. Method according to one of claims 1 to 3, characterized in that for the atomic layer deposition in a first step tri-methyl-aluminum AI(CHS)3 and titanium tetrachloride TiCk are bound to hydroxyl groups on the surface of the at least one cooling channel with the release of methane and hydrochloric acid, wherein in a second step ammonia reacts with the remaining methyl groups and titanium trichloride to form methane and hydrochloric acid in order to form titanium aluminum nitride.

6. The method according to any one of claims 1 to 3, characterized in that for the atomic layer deposition, in a first step, tris(butylcyclopentadienyl)yttrium is bound to hydroxyl groups on the surface of the at least one cooling channel with the release of (butylcyclopentadienyl)hydrogen, wherein in a second step, water reacts with the remaining (butylcyclopentadienyl)yttrium to form (butylcyclopentadienyl)hydrogen, thus forming yttrium oxide.

7. Method according to one of claims 4 to 6, characterized in that between the first and second steps a cleaning step (22) is carried out by flushing with an inert gas and / or that a cycle of the first step (21) and the second step (23) is repeated several times with or without the cleaning step (22) until a desired layer thickness is achieved, preferably in the range from 10 nm to 500 nm.

8. Method according to one of claims 2 to 7, characterized in that in the additive manufacturing the heat sink (12) is built up layer by layer on a substrate or a previously produced part of the heat sink (12), wherein a layer by layer construction is carried out by layer-by-layer deposition welding or layer-by-layer melting of powder material with a high-energy beam and layer-by-layer solidification of the powder melt.

9. Method according to claim 8, characterized in that the high-energy beam is a laser or electron beam (5).

10. Method according to one of the preceding claims, characterized in that the heat sink (12) is formed at least partially from steel, preferably stainless steel, in particular a high-alloy chromium-nickel steel, preferably X2CrNiMo17-12-2.

11. Method according to one of the preceding claims, characterized in that the heat sink (12) is formed at least partially from at least one element from the group comprising copper, aluminum and their alloys.

12. Method according to one of the preceding claims, characterized in that the heat sink (12) at least partially comprises a solder from the group comprising hard solders, Ni-based solders and Ni 620 according to ISO 17672.

13. Cooling element for an optical arrangement (25), in particular for an optical arrangement for microlithography, preferably produced according to the method according to one of the preceding claims, with a heat sink (12) with at least one cooling channel (16), which has at least one inlet (13) and at least one outlet (14) for a cooling medium which can flow through the at least one cooling channel (16), wherein a corrosion-resistant coating is arranged in the at least one cooling channel (16), wherein the corrosion-resistant coating has at least one component from the group comprising Al2O3, AlN, TiN, AlTiN, ZrO2, HfO2 and SiO2.

14. Cooling element according to claim 13, characterized in that the heat sink (12) is formed by joining, in particular soldering and / or welding, subcomponents and / or by a generative manufacturing process by deposited material layers.

15. Cooling element according to claim 13 or 14, characterized in that the cooling body (12) is cuboid-shaped and / or has a plurality of meandering cooling channels (16) in preferably several levels one above the other, wherein in particular the at least one cooling channel branches into a plurality of cooling channels.

16. Cooling element according to one of claims 13 to 15, characterized in that the at least one cooling channel (16) has a length of more than 100 mm, in particular more than 400 mm and a diameter of less than or equal to 10 mm, in particular less than or equal to 5 mm, preferably less than or equal to 3 mm.

17. A method for operating an optical arrangement (25), in particular an optical arrangement for microlithography, with a cooling element (11) according to one of claims 13 to 16, which has at least one cooling channel (16) through which a cooling medium, in particular demineralized water, is passed in order to absorb heat.

18. The method according to claim 17, characterized in that the optical arrangement is a projection exposure system (25) or mask inspection device.

19. Optical arrangement for microlithography, in particular projection exposure apparatus (25) or mask inspection device, with a cooling element according to one of claims 13 to 16 and / or manufactured by the method according to one of claims 1 to 12.

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