Optical system and projection exposure apparatus

Abstract

An optical system (100, 100A, 100B) for a projection exposure apparatus (1), having an optical element (102, 102A, 102B), and a temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 202G, 202H, 402A, 402B, 402C) attached to the optical element (102, 102A, 102B) and serving for connecting a temperature-regulating medium line (114) to the optical element, wherein the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 202G, 202H, 402A, 402B, 402C) has a connection portion (214, 414), through which a temperature-regulating medium (K) is guidable, wherein the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 202G, 202H, 402A, 402B, 402C) has a securing portion (230, 232, 234, 236, 238, 240, 434, 436, 438, 440), which is connected to the optical element (102, 102A, 102B), and wherein the connection portion (214, 414) is mechanically decoupled from the securing portion (230, 232, 234, 236, 238, 240, 434, 436, 438, 440).

Description

[0001] OPTICAL SYSTEM AND PROJECTION EXPOSURE APPARATUS

[0002] The present invention relates to an optical system and to a projection exposure apparatus comprising such an optical system.

[0003] The content of the priority apphcation DE 10 2024 205 617.0 is incorporated by reference in its entirety.

[0004] Microlithography is used to produce microstructured components, such as for example integrated circuits. The microlithography process is carried out using a lithography apparatus having an illumination system and a projection system. The image of a mask (reticle) illuminated by means of the illumination system is in this respect projected by means of the projection system onto a substrate, for example a silicon wafer, that has been coated with a light-sensitive layer (photoresist) and is arranged in the image plane of the projection system, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0005] Driven by the desire for ever smaller structures in the production of integrated circuits, EUV lithography apparatuses that use light at a wavelength ranging from 0.1 nm to 30 nm, in particular 13.5 nm, are currently under development. In the case of such EUV lithography apparatuses, because of the high absorption of light at this wavelength by most materials, reflective optical units, which is to say mirrors, must be used instead of - as previously - refractive optical units, which is to say lens elements.

[0006] The temperature of such a mirror can be regulated during operation of the projection system. For this purpose, temperature-regulating channels can be provided in the mirror, a temperature-regulating medium, for example in the form of demineralized water, being flushed through said channels for the purpose of dissipating heat or for the purpose of supplying heat. The temperature-regulating medium is supplied to the mirror and guided away from it again with the aid of temperature-regulating medium lines.

[0007] In order to connect such a temperature-regulating medium line to the mirror, a connection bush can be mounted on the mirror. In accordance with in-house insights, such a connection bush can have a tubular connection portion, which is insertable into a temperature-regulating channel as mentioned above, and a securing portion, which is connected to the connection portion and is adhesively bonded onto the optical element at the exterior. The securing portion can be embodied as disc-shaped or planar, in particular with a rectangular geometry. Owing to aging effects and / or shrinkage effects of the adhesive used, however, stresses and / or forces may be introduced into the mirror in an undesirable manner at the connection bush. This may result in deformation of a mirror surface of the mirror (known as: surface figure deformation, SFD). These deformations may cause optical properties of the mirror surface to be adversely influenced. This needs to be improved.

[0008] Against this background, an object of the present invention is to provide an improved optical system.

[0009] Accordingly, an optical system for a projection exposure apparatus is proposed. The optical system comprises an optical element, and a temperature-regulating medium line connection attached to the optical element and serving for connecting a temperature-regulating medium line to the optical element, wherein the temperature-regulating medium line connection has a connection portion, through which a temperature-regulating medium is guidable, wherein the temperature-regulating medium line connection has a securing portion, which is connected to the optical element, and wherein the connection portion is mechanically decoupled from the securing portion.

[0010] By virtue of the connection portion being mechanically decoupled from the securing portion, it is possible to reliably prevent forces and / or stresses from being able to be transferred from the securing portion to the connection portion and thus also to the optical element. The abovementioned undesirable deformations of an optically effective surface of the optical element are prevented or at least reduced as a result.

[0011] The optical system is preferably a projection optical unit of the projection exposure apparatus or part of such a projection optical unit. However, the optical system can also be an illumination system of the projection exposure apparatus or part of such an illumination system. The optical element is preferably a mirror, in particular an EUV mirror. However, the optical element can also be a lens element. In particular, the optical system can also be used for DUV lithography. The optical system can have as many optical elements as desired. Hereinafter, however, only one optical element is discussed.

[0012] Preferably a plurality of temperature-regulating medium line connections, in particular two temperature-regulating medium line connections, are attached to the optical element. However, there are any desired number of temperature- regulating medium line connections. Hereinafter, however, only one temperatureregulating medium line connection is discussed. The fact that the temperatureregulating medium line connection is "attached" to the optical element means in the present case that the temperature-regulating medium line connection is fixedly connected to the optical element, in particular cohesively connected to the optical element, preferably adhesively bonded to the optical element.

[0013] The optical element is preferably fabricated from a substrate, in particular from a mirror substrate. The substrate can be for example glass, a ceramic or a glass ceramic. The optical element preferably has an optically effective surface in the form of a mirror surface. The optically effective surface is suitable in particular for reflecting illumination radiation, in particular EUV radiation. The optically effective surface can be applied as a coating to the substrate. The optical element is preferably block-shaped. However, the optical element can in principle have any other geometry. The optical element is preferably a directly cooled mirror (DCM).

[0014] A plurality of temperature-regulating channels can run through the optical element, the temperature-regulating medium flowing through said channels during operation of the optical system. The temperature-regulating medium is preferably water, in particular demineralized water. The temperature-regulating channels can also be referred to as cooling channels. The temperature-regulating channels can be embodied for example as drilled holes incorporated into the substrate. The temperature-regulating channels preferably run below the optically effective surface. Hereinafter, only one temperature-regulating channel is discussed.

[0015] With the aid of the temperature-regulating medium line connection, the temperature-regulating medium line can be fluidically connected to the temperature-regulating channel, such that the temperature-regulating medium can flow from the temperature-regulating medium line through the temperature-regulating medium line connection into the temperature-regulating channel. The temperatureregulating medium line can be part of the optical system. The optical system can have a plurality of temperature-regulating medium line connections and a plurality of temperature-regulating medium lines. By way of example, one temperature-regulating medium line can be provided for supplying the temperature-regulating medium to the optical element, and another temperature-regulating medium line can be provided for guiding the temperature-regulating medium away from the optical element. Each temperature-regulating medium line can be assigned such a temperature-regulating medium line connection. The temperature-regulating medium line connection can also be referred to as a temperature-regulating medium connection, cooling water connection, connection bush or temperature-regulating medium line connection bush. The temperatureregulating medium line connection is preferably a one-piece component, in particular one which is materially in one piece. "One-piece" or "integral" means in the present case in particular that the temperature-regulating medium line connection is not composed of different subordinate components, but rather forms a continuous component. "Materially in one piece" means in the present case in particular that the temperature-regulating medium line connection is produced from the same material throughout. By way of example, iron-nickel alloys, in particular Invar, ultra-low expansion glass (ULE) or cordierite can be used as materials for the temperature-regulating medium line connection. However, other materials are also possible.

[0016] The connection portion is preferably hollow-cylindrical or tubular, such that the temperature-regulating medium can flow through the connection portion. With the aid of the connection portion, the temperature-regulating medium line connection can be fluidically connected to the temperature-regulating channel running through the optical element. For this purpose, the connection portion can be at least partly arranged within the optical element. For this purpose, the temperature-regulating channel can have a widening in the form of a cylindrical recess in which the connection portion can be at least partly received.

[0017] The temperature-regulating medium line connection can have a plurality of securing portions. There are in principle any desired number of securing portions. By way of example, the temperature-regulating medium line connection can have four or six securing portions. The securing portions can be arranged in a manner distributed uniformly around the connection portion. However, a non-uniform distribution can also be provided. Preferably, the securing portions are formed in one piece, in particular materially in one piece, with the connection portion. The securing portions are preferably adhesively bonded to the optical element. For this purpose, an adhesive bonding pad or an adhesive bonding joint can be assigned to each securing portion. The securing portions are preferably cylindrical. However, the securing portions can also have any other geometry. Hereinafter, only one securing portion is discussed.

[0018] The fact that the connection portion and the securing portion are "mechanically decoupled" from one another should be understood to mean in the present case in particular that no, or only a very reduced extent of, forces and / or stresses can be transferred from the securing portion to the connection portion, and vice versa. This can be achieved for example by the securing portion being connected to the connection portion with the aid of an elastically deformable decoupling structure. The decoupling structure can have a bridge-shaped geometry, for example.

[0019] This abovementioned decoupling structure preferably has a very low stiffness in comparison with the connection portion and the securing portion, such that the mechanical decoupling of the connection portion from the securing portion, and vice versa, can be realized. In the present case, the "stiffness" should be understood to mean the resistance of a body, in the present case the decoupling structure, to an elastic deformation imposed thereon by an external load and conveys the relationship between the load on the body and its deformation. The stiffness is determined by the material of the body and its geometry.

[0020] In accordance with one embodiment, the connection portion is arranged at least partly within the optical element, wherein the securing portion is arranged outside the optical element.

[0021] In particular, the connection portion is arranged within the abovementioned recess of the optical element. In particular, the securing portion is adhesively bonded onto the optical element at the exterior and is thus preferably arranged completely outside the optical element. The optical element preferably has a block-shaped base body, and a cylindrical decoupling pin extends out from said body. The temperature-regulating channel runs through the decoupling pin. Within the decoupling pin, the temperature-regulating channel preferably widens to the abovementioned recess in which the connection portion is received. The securing portion is preferably adhesively bonded to an end face of the decoupling pin.

[0022] In accordance with a further embodiment, the temperature-regulating medium line connection has a plurality of securing portions arranged in distributed fashion around the connection portion.

[0023] The connection portion can preferably be constructed rotationally symmetrically with respect to an axis of symmetry or central axis. The securing portions can be arranged in a manner distributed uniformly around this central axis. However, this is not mandatory. The securing portions can also be arranged in a manner distributed non-uniformly around the central axis. As mentioned above, the temperature-regulating medium line connection can have four or six securing portions, for example. However, three or more than six securing portions can also be provided.

[0024] In accordance with a further embodiment, the connection portion is mechanically decoupled from the securing portions with the aid of elastically deformable decoupling structures.

[0025] With the aid of the decoupling structures, the securing portions can be connected to the connection portion in one piece, in particular materially in one piece. Each securing portion can be assigned such a decoupling structure. In the simplest case, the decoupling structure is bridge-shaped. It is also possible for a common decoupling structure to be assigned to a plurality of securing portions. This decoupling structure then additionally mechanically decouples the plurality of securing portions from one another. By way of example, it is possible for one decoupling structure to be assigned in each case to two securing portions. The decoupling structures have a significantly reduced stiffness in comparison with the connection portion and with the securing portions. This can be achieved for example by virtue of the decoupling structures having a small cross-sectional area. In other words, the decoupling structures form cross-sectional narrowings between the connection portion and the securing portions. In the present case, the decoupling structures being "elastically deformable" should be understood to mean in particular that the decoupling structures can be brought from a non-deformed state into a deformed state in each case by the application of a force. Once this force no longer acts on the decoupling structures, the latter independently deform back from the deformed state into the non-deformed state. The decoupling structures can function as flexures arranged between the securing portions and the connection portion. In the present case, a "flexure" should be understood to mean in particular generally a region, for example a cross-sectional narrowing or thinning, of a component, which region enables a relative movement between two rigid-body regions of the component by bending or torsion or the combination thereof. By adapting the stiffness of the flexure, it is possible for the latter to be adapted to any desired applications. Such a flexure can be embodied for example as bridge-shaped or in the form of a spring, in particular in the form of a leaf spring.

[0026] In accordance with a further embodiment, each decoupling structure has an elastically deformable first bridge portion connecting two securing portions to one another, and an elastically deformable second bridge portion connecting the first bridge portion and the connection portion to one another. In this case, the decoupling structures are each T-shaped, in particular. The first bridge portions can run for example in straight fashion between two adjacent securing portions. However, the first bridge portions can also be arcuately curved. The first bridge portions and / or the second bridge portions can each be configured like a leaf spring. The second bridge portions connect the connection portion to the first bridge portions. In this case, the second bridge portions are preferably centrally linked to the first bridge portions. Both the first bridge portions and the second bridge portions can have in cross section for example a rectangular, an oval, a circular, a triangular or any other cross-sectional geometry. By varying the cross-sectional geometry of the bridge portions, it is possible for the stiffness of the bridge portions or the decoupling structures to be adapted in any desired way.

[0027] In accordance with a further embodiment, the connection portion has a perforation, through which the temperature-regulating medium is guidable, wherein the perforation preferably has an at least partly frustoconical inner surface.

[0028] The perforation is preferably constructed rotationally symmetrically with respect to the abovementioned central axis of the connection portion. The perforation can be a drilled hole. By way of example, the perforation can be a conical or frustoconical drilled hole. In this case, the perforation widens proceeding from the end face of the decoupling pin in the direction of the temperature-regulating channel. What can be achieved by means of the at least partly frustoconical inner surface is that a sudden change in cross section between the perforation of the connection portion and the temperature-regulating channel is avoided or reduced. This makes it possible to reduce or prevent flow induced vibrations (FIV).

[0029] In accordance with a further embodiment, the connection portion has a sealing groove for receiving a sealing element, which seals the connection portion vis-a- vis the optical element.

[0030] The sealing groove preferably faces away from the abovementioned inner surface of the connection portion. The sealing groove can be a rectangular ring groove extending completely around the abovementioned central axis. The sealing element can be for example an O-ring that is received in the sealing groove. The connection portion preferably has a first outer surface and also a second outer surface at the exterior. The outer surfaces are cylindrical. The sealing groove is arranged between the first outer surface and the second outer surface as viewed along the central axis. In this case, the second outer surface preferably has a larger external diameter than the first outer surface. The sealing element seals the connection portion preferably radially vis-a-vis the optical element. In particular, the sealing element seals the connection portion radially vis-a-vis the recess provided in the decoupling pin.

[0031] In accordance with a further embodiment, the temperature-regulating medium line connection has a connecting portion for connecting the temperature-regulating medium line connection to a mounting element, wherein the connecting portion is connected to the connection portion with the aid of a bridge portion, and wherein a securing flange of the temperature-regulating medium line is arrangeable between the temperature-regulating medium line connection and the mounting element.

[0032] The temperature-regulating medium line connection can have a plurality of such connecting portions. By way of example, three connecting portions are provided, arranged in a manner distributed uniformly around the abovementioned central axis. It is also possible to provide two connecting portions arranged offset by 180° with respect to one another. The connecting portions are connected to the connection portion in one piece with the aid of bridge portions. The bridge portions can have perforations. The mounting element can be part of the optical system. The mounting element can be screwed to the temperature-regulating medium line connection, wherein the securing flange of the temperature-regulating medium line can be pressed between the mounting element and a flange surface of the temperature-regulating medium line connection, in particular of the connection portion.

[0033] In accordance with a further embodiment, the connecting portion is cylindrical, wherein the connecting portion has a threaded hole.

[0034] In terms of external shape, the connecting portion can have a cylindrical outer surface and also a frustoconical cone surface. In this case, the mounting element can be guided and / or positioned at the connecting portion. A securing element, for example in the form of a screw, can be screwed into the threaded hole in order to releasably connect the mounting element to the temperature-regulating medium line connection. For the case where the temperature-regulating medium line connection is produced from a brittle material, such as for example cordierite, the threaded hole can be provided at a metallic threaded insert that is adhesively bonded into the respective connecting portion.

[0035] In accordance with a further embodiment, the temperature-regulating medium line connection has a flange surface facing away from the optical element. The flange surface can extend around the central axis in a ring-shaped manner. The flange surface can be planar. The securing flange of the temperature-regulating medium line can bear against the flange surface. A sealing element, for example in the form of an Oring, can be arranged between the securing flange and the flange surface. The sealing element can be pressed between the flange surface and the securing flange of the temperature-regulating medium line. The securing flange can have a sealing groove in which the sealing element is arranged. Alternatively, a sealing groove in which the sealing element can be received can also be incorporated into the flange surface. The sealing groove can have a dovetailshaped cross-sectional geometry.

[0036] In accordance with a further embodiment, the optical element has a base body and a decoupling pin extending out from the base body, wherein the temperatureregulating medium line connection is attached to the decoupling pin.

[0037] Preferably, the temperature-regulating medium line connection is adhesively bonded to the decoupling pin. In particular, the temperature-regulating medium line connection is adhesively bonded to an end face, as mentioned above, of the decoupling pin with the aid of the securing portions of said connection. The decoupling pin is preferably cylindrical. That is to say in particular that the decoupling pin can be constructed rotationally symmetrically with respect to an axis of symmetry or central axis. A further mechanical decoupling of the temperatureregulating medium line connection from the base body can be achieved with the aid of the decoupling pin.

[0038] In accordance with a further embodiment, the decoupling pin has a temperatureregulating channel constructed rotationally symmetrically with respect to a central axis, wherein the decoupling pin is constructed asymmetrically with respect to the central axis, and wherein the decoupling pin is preferably oval in cross section.

[0039] In this case, the decoupling pin is not constructed rotationally symmetrically with respect to the central axis, but rather asymmetrically. In principle, the decoupling pin can have any desired geometry in cross section. By way of example, the decoupling pin can also be embodied as rectangular with rounded corners in cross section, that is to say perpendicular to the central axis. The temperatureregulating channel runs both through the decoupling pin and through the base body of the optical element. In this case, the temperature-regulating channel widens, within the decoupling pin, to the abovementioned recess in which the connection portion of the temperature-regulating medium line connection is received.

[0040] In accordance with a further embodiment, the temperature-regulating medium line connection is constructed asymmetrically with respect to the central axis.

[0041] In this case, the temperature-regulating medium line connection has a flattened geometry. By virtue of the asymmetrical construction of the temperature-regulating medium line connection, the latter can be used even under confined space conditions, particularly in the case of asymmetrically constructed decoupling pins. This makes it possible to use the temperature-regulating medium line connection particularly in conjunction with flat or thin optical elements.

[0042] In accordance with a further embodiment, the connection portion has bypass holes and / or bypass perforations extending from an inner surface of the connection portion to an outer surface of the connection portion, wherein the bypass holes are arranged in particular obliquely with respect to a central axis of the connection portion.

[0043] The connection portion is in particular tubular or hollow-cylindrical. A bypass perforation differs from a bypass hole in that the bypass perforation is preferably not circular. The bypass holes are oriented in particular at an oblique angle with respect to the central axis. Flow capture bumps can be provided at inlets of the bypass holes.

[0044] In accordance with a further embodiment, the securing portion, facing the optical element, has an adhesive bonding joint, with the aid of which the securing portion is adhesively bonded to the optical element.

[0045] For the purpose of mounting the temperature-regulating medium line connection, the latter is firstly mounted on the optical element in such a way that the connection portion is pushed and / or screwed into the recess of the decoupling pin. A suitable tool is used to set a suitable distance between a respective end face of the securing portions and the end face of the decoupling pin. Afterwards, adhesive is introduced or applied between the end face of the securing portions and the end face of the decoupling pin. This can be done for example by virtue of recesses or holes being provided in the securing portions, the adhesive being able to be injected through said recesses or holes. The adhesive bonding joints are formed after the curing and / or crosslinking of the adhesive. Furthermore, a projection exposure apparatus comprising such an optical system is proposed.

[0046] The projection exposure apparatus can be an EUV lithography apparatus. "EUV" stands for "extreme ultraviolet" and denotes a wavelength of the operating light of between 0.1 nm and 30 nm. The projection exposure apparatus can also be a DUV lithography apparatus. "DUV" stands for "deep ultraviolet" and denotes a wavelength of the operating light of between 30 nm and 250 nm.

[0047] "A(n); one" in the present case should not necessarily be understood as restrictive to exactly one element. Rather, a plurality of elements, such as for example two, three or more, can also be provided. Any other numeral used here, too, should not be understood to the effect that there is a restriction to exactly the stated number of elements. Rather, numerical deviations upwards and downwards are possible, unless indicated otherwise.

[0048] The embodiments and features described for the proposed optical system apply correspondingly to the proposed projection exposure apparatus, and vice versa.

[0049] Further possible implementations of the invention also encompass not explicitly mentioned combinations of features or embodiments that are described above or hereinafter with respect to the exemplary embodiments. A person skilled in the art will also add individual aspects as improvements or supplementations to the respective basic form of the invention.

[0050] Further advantageous configurations and aspects of the invention are the subject matter of the dependent claims and also of the exemplary embodiments of the invention that are described below. The invention is explained in greater detail hereinafter on the basis of preferred embodiments with reference to the appended figures.

[0051] Figure 1 shows a schematic meridional section of a projection exposure apparatus for EUV projection lithography!

[0052] Figure 2 shows a schematic view of one embodiment of an optical system for the projection exposure apparatus in accordance with Figure 1!

[0053] Figure 3 shows a schematic partial sectional view of a further embodiment of an optical system for the projection exposure apparatus in accordance with Figure 1! Figure 4 shows a schematic plan view of one embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 3;

[0054] Figure 5 shows a schematic perspective view of the temperature-regulating medium line connection in accordance with Figure 4;

[0055] Figure 6 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 4;

[0056] Figure 7 shows a schematic plan view of a further embodiment of a temperatureregulating medium line connection for the optical system in accordance with Figure 3;

[0057] Figure 8 shows a schematic perspective view of the temperature-regulating medium line connection in accordance with Figure 7;

[0058] Figure 9 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure T,

[0059] Figure 10 shows a schematic plan view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 3;

[0060] Figure 11 shows a schematic perspective view of the temperature-regulating medium line connection in accordance with Figure 10;

[0061] Figure 12 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 10;

[0062] Figure 13 shows a schematic plan view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 3;

[0063] Figure 14 shows a schematic perspective view of the temperature-regulating medium line connection in accordance with Figure 13;

[0064] Figure 15 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 13; Figure 16 shows a schematic partial sectional view of a further embodiment of an optical system for the projection exposure apparatus in accordance with Figure 1;

[0065] Figure 17 shows a schematic bottom view of one embodiment of a temperatureregulating medium line connection for the optical system in accordance with Figure 16;

[0066] Figure 18 shows a schematic perspective view of the temperature-regulating medium line connection in accordance with Figure 17;

[0067] Figure 19 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 17;

[0068] Figure 20 shows a schematic bottom view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 16;

[0069] Figure 21 shows a schematic perspective view of the temperature-regulating medium line connection in accordance with Figure 20;

[0070] Figure 22 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 20;

[0071] Figure 23 shows a schematic bottom view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 16;

[0072] Figure 24 shows a schematic perspective view of the temperature-regulating medium line connection in accordance with Figure 23;

[0073] Figure 25 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 23;

[0074] Figure 26 shows a schematic perspective view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 3;

[0075] Figure 27 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 26; Figure 28 shows a schematic perspective view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 3;

[0076] Figure 29 shows a schematic sectional view of the temperature-regulating medium line connection in accordance with Figure 28;

[0077] Figure 30 shows a schematic perspective sectional view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 3;

[0078] Figure 31 shows a further schematic sectional view of the optical system in accordance with Figure 3;

[0079] Figure 32 shows a further schematic sectional view of the optical system in accordance with Figure 3; and

[0080] Figure 33 shows a schematic perspective sectional view of a further embodiment of a temperature-regulating medium line connection for the optical system in accordance with Figure 3.

[0081] In the figures, identical or functionally identical elements have been provided with the same reference signs, unless indicated otherwise. Furthermore, it should be noted that the illustrations in the figures are not necessarily true to scale.

[0082] Figure 1 shows one embodiment of a projection exposure apparatus 1 (lithography apparatus), in particular an EUV lithography apparatus. One embodiment of an illumination system 2 of the projection exposure apparatus 1 has, in addition to a light or radiation source 3, an illumination optical unit 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a module separate from the rest of the illumination system 2. In this case, the illumination system 2 does not comprise the light source 3.

[0083] A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable by way of a reticle displacement drive 9, in particular in a scanning direction. Figure 1 depicts, for explanation purposes, a Cartesian coordinate system with an x-direction x, a ydirection y, and a z-direction z. The x-direction x runs perpendicularly into the plane of the drawing. The ydirection y runs horizontally, and the z-direction z runs vertically. The scanning direction runs along the ydirection y in Figure 1. The z-direction z runs perpendicularly to the object plane 6.

[0084] The projection exposure apparatus 1 comprises a projection optical unit 10. The projection optical unit 10 serves for imaging the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle different from 0° between the object plane 6 and the image plane 12 is also possible.

[0085] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable by way of a wafer displacement drive 15, in particular along the ydirection y. The displacement, firstly, of the reticle 7 by way of the reticle displacement drive 9 and, secondly, of the wafer 13 by way of the wafer displacement drive 15 can be implemented so as to be synchronized with one another.

[0086] The light source 3 is an EUV radiation source. The light source 3 emits in particular EUV radiation 16, which is also referred to below as used radiation, illumination radiation or illumination light. The used radiation 16 has in particular a wavelength in the range of between 5 nm and 30 nm. The light source 3 can be a plasma source, for example an LPP (short for: laser produced plasma) source or a DPP (short for: gas-discharge produced plasma) source. It can also be a synchrotron-based radiation source. The light source 3 can be an FEL (short for: free- electron laser).

[0087] The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 can be a collector having one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be impinged upon by the illumination radiation 16 with grazing incidence (abbreviated as: GI), which is to say with angles of incidence greater than 45°, or with normal incidence (abbreviated as: Nl), which is to say with angles of incidence less than 45°. The collector 17 can be structured and / or coated firstly to optimize its reflectivity for the used radiation and secondly to suppress extraneous light. Downstream of the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optical unit 4.

[0088] The illumination optical unit 4 comprises a deflection mirror 19 and, disposed downstream thereof in the beam path, a first facet mirror 20. The deflection mirror 19 can be a plane deflection mirror or alternatively a mirror with a beam-influencing effect going beyond the pure deflection effect. Alternatively or additionally, the deflection mirror 19 can be embodied as a spectral filter separating a used light wavelength of the illumination radiation 16 from extraneous light having a wavelength that deviates therefrom. If the first facet mirror 20 is arranged in a plane of the illumination optical unit 4 that is optically conjugate to the object plane 6 as a field plane, said facet mirror is also referred to as a field facet mirror. The first facet mirror 20 comprises a multiplicity of individual first facets 21, which can also be referred to as field facets. Only some of these first facets 21 are illustrated in Figure 1 by way of example.

[0089] The first facets 21 can be embodied as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partly circular edge contour. The first facets 21 can be embodied as plane facets or alternatively as facets with convex or concave curvature.

[0090] As known for example from DE 10 2008 009 600 Al, the first facets 21 themselves can also be composed in each case of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 20 can be embodied in particular as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 Al.

[0091] The illumination radiation 16 runs horizontally, i.e. along the ydirection y, between the collector 17 and the deflection mirror 19.

[0092] In the beam path of the illumination optical unit 4, a second facet mirror 22 is disposed downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optical unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optical unit 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 Al, EP 1 614 008 Bl, and US 6,573,978. The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0093] The second facets 23 can likewise be macroscopic facets, which can for example have a round, rectangular or else hexagonal boundary, or can alternatively be facets composed of micromirrors. In this regard, reference is likewise made to DE 10 2008 009 600 Al.

[0094] The second facets 23 can have plane or alternatively convexly or concavely curved reflection surfaces.

[0095] The illumination optical unit 4 thus forms a doubly faceted system. This fundamental principle is also referred to as a fly’s eye condenser (or fly’s eye integrator).

[0096] It can be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugate to a pupil plane of the projection optical unit 10. In particular, the second facet mirror 22 can be arranged so as to be tilted in relation to a pupil plane of the projection optical unit 10, as described for example in DE 10 2017 220 586 Al.

[0097] The individual first facets 21 are imaged into the object field 5 with the aid of the second facet mirror 22. The second facet mirror 22 is the last beam-shaping mirror or else actually the last mirror for the illumination radiation 16 in the beam path upstream of the object field 5.

[0098] In a further embodiment (not illustrated) of the illumination optical unit 4, a transfer optical unit contributing in particular to the imaging of the first facets 21 into the object field 5 can be arranged in the beam path between the second facet mirror 22 and the object field 5. The transfer optical unit can have exactly one mirror or, alternatively, even two or more mirrors, which are arranged in succession in the beam path of the illumination optical unit 4. The transfer optical unit can in particular comprise one or two normal-incidence mirrors (NI mirrors) and / or one or two grazing-incidence mirrors (GI mirrors).

[0099] In the embodiment shown in Figure 1, the illumination optical unit 4 has exactly three mirrors downstream of the collector 17, specifically the deflection mirror 19, the first facet mirror 20, and the second facet mirror 22. In a further embodiment of the illumination optical unit 4, the deflection mirror 19 can also be omitted, and so the illumination optical unit 4 can then have exactly two mirrors downstream of the collector 17, specifically the first facet mirror 20 and the second facet mirror 22.

[0100] The imaging of the first facets 21 into the object plane 6 by means of the second facets 23 or using the second facets 23 and a transfer optical unit is routinely only approximate imaging.

[0101] The projection optical unit 10 comprises a plurality of mirrors Mi, which are consecutively numbered in accordance with their arrangement in the beam path of the projection exposure apparatus 1.

[0102] In the example illustrated in Figure 1, the projection optical unit 10 comprises six mirrors Ml to M6. Alternatives with four, eight, ten, twelve or any other number of mirrors Mi are likewise possible. The projection optical unit 10 is a doubly obscured optical unit. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optical unit 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6 and, for example, can be 0.7 or 0.75.

[0103] Reflection surfaces of the mirrors Mi can be embodied as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. Just like the mirrors of the illumination optical unit 4, the mirrors Mi can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0104] The projection optical unit 10 has a large object-image offset in the ydirection y between a ycoordinate of a centre of the object field 5 and a ycoordinate of the centre of the image field 11. This object-image offset in the ydirection y can be of approximately the same magnitude as a z-distance between the object plane 6 and the image plane 12.

[0105] The projection optical unit 10 can be embodied in particular in anamorphic fashion. It has in particular different imaging scales Bx, By in the x- and y- directions x, y. The two imaging scales Bx, By of the projection optical unit 10 are preferably (Bx, By) = (+ / -0.25, + / -0.125). A positive imaging scale B means imaging without image inversion. A negative sign for the imaging scale B means imaging with image inversion.

[0106] The projection optical unit 10 consequently leads to a reduction in size with a ratio of 4'1 in the x-direction x, i.e. in a direction perpendicular to the scanning direction.

[0107] The projection optical unit 10 leads to a reduction in size of 8A in the ydirection y, i.e. in the scanning direction.

[0108] Other imaging scales are hkewise possible. Imaging scales with the same sign and the same absolute value in the x-direction x and ydirection y are also possible, for example with absolute values of 0.125 or of 0.25.

[0109] The number of intermediate image planes in the x-direction x and in the ydirection y in the beam path between the object field 5 and the image field 11 can be the same or can differ, depending on the embodiment of the projection optical unit 10. Examples of projection optical units with different numbers of such intermediate images in the x-direction x and ydirection y are known from US 2018 / 0074303 Al.

[0110] In each case one of the second facets 23 is assigned to exactly one of the first facets 21 for forming a respective illumination channel for illuminating the object field 5. In particular, this can produce illumination according to the Kohler principle. The far field is decomposed into a multiplicity of object fields 5 with the aid of the first facets 21. The first facets 21 create a plurality of images of the intermediate focus on the second facets 23 respectively assigned to them.

[0111] The first facets 21 are each imaged onto the reticle 7 by an assigned second facet 23 with images overlaid over one another for the purpose of illuminating the object field 5. The illumination of the object field 5 is in particular as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be attained by overlaying different illumination channels.

[0112] The illumination of the entrance pupil of the projection optical unit 10 can be defined geometrically by an arrangement of the second facets 23. The intensity distribution in the entrance pupil of the projection optical unit 10 can be set by selecting the illumination channels, in particular the subset of the second facets 23, which guide light. This intensity distribution is also referred to as illumination setting or illumination pupil filling. A likewise preferred pupil uniformity in the region of portions of an illumination pupil of the illumination optical unit 4 that are illuminated in a defined manner can be achieved by a redistribution of the illumination channels.

[0113] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optical unit 10 are described below.

[0114] The projection optical unit 10 can have a homocentric entrance pupil, in particular. The latter can be accessible. It can also be inaccessible.

[0115] The entrance pupil of the projection optical unit 10 regularly cannot be exactly illuminated with the second facet mirror 22. In the case of imaging by the projection optical unit 10 which telecentrically images the centre of the second facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find an area in which the spacing of the aperture rays that is determined in pairs becomes minimal. This area represents the entrance pupil or an area in real space conjugate thereto. In particular, this area exhibits a finite curvature.

[0116] It may be the case that the projection optical unit 10 has different positions of the entrance pupil for the tangential beam path and for the sagittal beam path. In this case, an imaging element, in particular an optical component of the transfer optical unit, should be provided between the second facet mirror 22 and the reticle 7. With the aid of this optical element, the different position of the tangential entrance pupil and of the sagittal entrance pupil can be taken into account.

[0117] In the arrangement of the components of the illumination optical unit 4 illustrated in Figure 1, the second facet mirror 22 is arranged in an area conjugate to the entrance pupil of the projection optical unit 10. The first facet mirror 20 is arranged so as to be tilted with respect to the object plane 6. The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the second facet mirror 22.

[0118] Figure 2 shows a schematic view of one embodiment of an optical system 100 for the projection exposure apparatus 1.

[0119] The optical system 100 can be a projection optical unit 10 as explained above or part of such a projection optical unit 10. Therefore, the optical system 100 can also be referred to as projection optical unit. However, the optical system 100 can also be an illumination system 2 as explained above, or part of such an illumination system 2. Therefore, the optical system 100 can alternatively also be referred to as illumination system. However, it is assumed hereinafter that the optical system 100 is a projection optical unit 10 or part of such a projection optical unit 10. The optical system 100 is suitable for EUV lithography. However, the optical system 100 can also be suitable for DUV lithography.

[0120] The optical system 100 can comprise a plurality of optical elements 102, only one of which is shown in Figure 2, however. Therefore, only one optical element 102 is discussed below. The optical element 102 can be one of the mirrors Ml to M6. The optical element 102 comprises a substrate 104 and an optically effective surface 106, for example a mirror surface. The substrate 104 can also be referred to as mirror substrate. The substrate 104 can comprise glass, ceramic, glass ceramic or other suitable materials. The optically effective surface 106 is suitable for reflecting illumination radiation 16, in particular EUV radiation. The optical element 102 can have any desired geometry. Figure 2 illustrates the optical element 102 and the optically effective surface 106 only in a greatly simplified way.

[0121] A plurality of temperature-regulating channels 108 lead through the substrate 104, only one of which channels is shown in Figure 2, however. Therefore, only one temperature-regulating channel 108 is referred to below. The temperatureregulating channel 108 can also be referred to as cooling channel. The temperature-regulating channel 108 can be introduced into the substrate 104 with the aid of a removing production method, for example with the aid of deep hole drilling. In the simplest case, the temperature-regulating channel 108 - as shown in Figure 2 - can lead in straight fashion through the substrate 104. However, the temperature-regulating channel 108 can also be curved, for example curved in meandering fashion. However, not only is it possible for the optical element 102 to have such a temperature-regulating channel 108, but it is also possible for any other components of the optical system 100, such as for example carrying structures of the optical element 102, to have such a temperature-regulating channel 108.

[0122] The optical element 102 is assigned a temperature-regulating device 110, which is part of the optical system 100. The temperature-regulating device 110 can also be referred to as cooling device. The temperature-regulating channel 108 can be part of the temperature-regulating device 110. With the aid of the temperatureregulating device 110, a temperature-regulating medium K, for example in the form of demineralized water, can be flushed through the temperature-regulating channel 108 in order to dissipate from the optical element 102 heat Q introduced into the optical element 102 with the aid of the illumination radiation 16, for example. Conversely, heat Q can also be supplied to the optical element 102 by the temperature-regulating medium K. However, it is assumed hereinafter that heat Q is dissipated with the aid of the temperature-regulating medium K. Therefore, the temperature-regulating medium K can also be referred to as cooling medium. The temperature-regulating medium K is a liquid. The temperature-regulating medium K can also be an oil.

[0123] Besides the temperature-regulating channel 108, the temperature-regulating device 110 has a pump 112, in particular a water pump, and a temperature-regulating medium line 114, which fluidically connects an inlet or an outlet of the pump 112 to the temperature-regulating channel 108. The temperature-regulating medium line 114 can be multipartite. Preferably, the temperature-regulating medium line 114 - in contrast to what is shown in Figure 2 - is not guided to the optical element 102 laterally, but rather on the rear side. For this purpose, suitable temperature-regulating medium line connections can be provided on the optical element 102, and the temperature-regulating medium line 114 can be flanged to said connections. The temperature-regulating medium line 114 can be at least partly flexibly deformable.

[0124] Figure 3 shows a schematic partial sectional view of a further embodiment of an optical system 100A.

[0125] The optical system 100A has an optical element 102A. The optical element 102A can be identical with the optical element 102 mentioned above. The optical element 102A has a base body 116, and a decoupling pin 118 extends out from said body. The base body 116 and the decoupling pin 118 are produced from the substrate 104. The base body 116 and the decoupling pin 118 are embodied in one piece, in particular materially in one piece. "In one piece" or "integrally" means in the present case that the optical element 102A is not composed of different subordinate components, rather that the base body 116 and the decoupling pin 118 together form a common component, namely the optical element 102A. "Materially in one piece" means that the base body 116 and the decoupling pin 118 are produced from the same material throughout, namely the substrate 104.

[0126] In particular, the decoupling pin 118 extends beyond a surface 120 of the base body 116. The surface 120 can be a rear side of the optical element 102A. The surface 120 can also be a bottom of a recess in which the decoupling pin 118 is received. The decoupling pin 118 is constructed rotationally symmetrically with respect to an axis of symmetry or central axis 122. That is to say, in particular, that the decoupling pin 118 has a cylindrical outer surface 124.

[0127] A temperature-regulating channel 108 as mentioned above is guided through the decoupling pin 118 and through the base body 116. The temperature-regulating channel 108 can also be referred to as cooling channel. The temperature-regulating channel 108 can be a drilled hole. The temperature-regulating medium K flows through the temperature-regulating channel 108 during operation of the optical system 100A. The temperature-regulating channel 108 is constructed rotationally symmetrically with respect to the central axis 122. The temperatureregulating channel 108 can run centrally through the decoupling pin 118. The decoupling pin 118 comprises an end face 126 arranged parallel to and at a distance from the surface 120. Adjacent to the end face 126, the temperature-regulating channel 108 is widened into a recess 128 having a larger diameter than the temperature-regulating channel 108. The recess 128 merges into the temperatureregulating channel 108 with the aid of a shoulder 130.

[0128] The temperature-regulating medium line 114 is connected to the optical element 102A, in particular to the decoupling pin 118, with the aid of a connection system 200 in such a way that the temperature medium K is guided from the temperature-regulating medium line 114 into the temperature-regulating channel 108. The connection system 200 comprises a temperature-regulating medium line connection 202A, which is connected, in particular adhesively bonded, to the decoupling pin 118, in particular to the end face 126. The temperature-regulating medium line connection 202A is preferably suitable both for lowNA applications and for high-NA applications.

[0129] The temperature-regulating medium line connection 202A is sealed radially vis- a-vis the recess 128 of the decoupling pin 118 with the aid of a sealing element 204, in particular in the form of an Oring. The temperature-regulating medium line 114 has a securing flange 132, which is sealed vis-a-vis the temperature-regulating medium line connection 202A with the aid of a further sealing element 206, in particular in the form of an Oring. In order to press the securing flange 132 against the temperature-regulating medium line connection 202A, the connection system 200 comprises a ring-shaped mounting element 208, which is connected to the temperature-regulating medium line connection 202A with the aid of securing elements 210, in particular in the form of screws.

[0130] Figure 4 shows a schematic plan view of a temperature-regulating medium line connection 202A as mentioned above. Figure 5 shows a schematic perspective view of the temperature-regulating medium line connection 202A. Figure 6 shows a schematic sectional view of the temperature-regulating medium hne connection 202A. Hereinafter, reference is made to Figures 4 to 6 concurrently.

[0131] The temperature-regulating medium hne connection 202A is assigned an axis of symmetry or central axis 212. The central axis 212 can correspond to the central axis 122 or can be arranged coaxially therewith. The temperature-regulating medium line connection 202A comprises a tubular or hollow-cylindrical connection portion 214. The connection portion 214 has a sealing groove 216 at the exterior. The sealing groove 216 is a ring groove. A sealing element 204 (not shown) as mentioned above is received in the sealing groove 216. The connection portion 214 together with the sealing element 204 is at least partly received in the recess 128.

[0132] The connection portion 214 has a first outer surface 218 and a second outer surface 220. The outer surfaces 218, 220 are preferably each cylindrical. In this case, the second outer surface 220 can have a larger external diameter than the first outer surface 218.

[0133] At the interior, the connection portion has a perforation 222, through which the temperature-regulating medium K can flow. The perforation 222 has an inner surface 224. The inner surface 224 is not cylindrical, however, but rather frusto- conical or conical. In particular, the inner surface 224 widens from top to bottom in the orientation in Figure 6. This makes it possible to reduce turbulences of the temperature-regulating medium K when the latter flows into the temperatureregulating channel 108 from the perforation 222. This makes it possible to prevent or at least reduce flow induced vibrations (FIV).

[0134] The connection portion 214 furthermore comprises a circular flange surface 226. The flange surface 226 extends around the central axis 212. A sealing element 206 (not shown) as mentioned above bears against the flange surface 226. Facing away from the flange surface 226, the connection portion 214 comprises an end face 228.

[0135] The temperature-regulating medium line connection 202A furthermore comprises a plurality of securing portions 230, 232, 234, 236, 238, 240. The securing portions 230, 232, 234, 236, 238, 240 are cylindrical. The securing portions 230, 232, 234, 236, 238, 240 are arranged in a manner distributed around the central axis 212. Facing the optical element 102A, each securing portion 230, 232, 234, 236, 238, 240 is assigned an adhesive bonding pad or an adhesive bonding joint 242, only one of which is provided with a reference sign in Figure 5, however. With the aid of the adhesive bonding joints 242, the securing portions 230, 232, 234, 236, 238, 240 are cohesively connected to the end face 126 of the decoupling pin 118. There are any desired number of securing portions 230, 232, 234, 236, 238, 240. By way of example, six securing portions 230, 232, 234, 236, 238, 240 are provided.

[0136] As is shown on the basis of the securing portion 232 in Figure 4 and Figure 6, each securing portion 230, 232, 234, 236, 238, 240 has a cylindrical outer surface 244 and also a central perforation 246. The perforation 246 tapers to a hole 248 leading to an end face 250 of the securing portion 232. Through the perforation 246 and the hole 248, adhesive can be brought to the end face 250 in order to form the adhesive bonding joints 242. For this purpose, the adhesive can be injected into the perforation 246 and / or the hole 248.

[0137] The securing portions 230, 232, 234, 236, 238, 240 are mechanically decoupled from the connection portion 214. The fact that the securing portions 230, 232, 234, 236, 238, 240 are "mechanically decoupled" from the connection portion 214 should be understood to mean in the present case in particular that no, or only a very reduced amount of, forces can be transferred from the securing portions 230, 232, 234, 236, 238, 240 to the connection portion 214, and vice versa. Consequently, for example, stresses and / or forces generated by shrinkage effects of the adhesive bonding joints 242 cannot be transferred to the connection portion 214.

[0138] This mechanical decoupling is achieved by virtue of the securing portions 230, 232, 234, 236, 238, 240 being connected to the connection portion 214 in one piece, in particular materially in one piece, with the aid of elastically deformable decoupling structures 252, 254, 256. Each of the decoup ling structures 252, 254, 256 has - as shown in Figure 4 - an elastically deformable first bridge portion 258, 260, 262 connecting in each case two adjacent securing portions 230, 232, 234, 236, 238, 240 to one another. By way of example, one first bridge portion 258 connects the securing portions 230, 232 to one another. A further first bridge portion 260 connects the securing portions 234, 236 to one another. A further first bridge portion 262 connects the securing portions 238, 240 to one another.

[0139] The first bridge portions 258, 260, 262 are in turn connected to the connection portion 214 with the aid of second bridge portions 264, 266, 268. In this way, for example, one second bridge portion 264 connects the first bridge portion 258 to the connection portion 214. A further second bridge portion 266 connects the first bridge portion 260 to the connection portion 214. A further second bridge portion 268 connects the first bridge portion 262 to the connection portion 214. The two bridge portions 264, 266, 268 are elastically deformable.

[0140] The temperature-regulating medium line connection 200A furthermore comprises a plurality of connecting portions 270, 272, 274. The mounting element 208 (not shown) is mounted on the connecting portions 270, 272, 274. For this purpose, each connecting portion has a threaded hole 276, as is shown on the basis of the connecting portion 274 in Figure 4. Securing elements 210 (not shown) as mentioned above are screwed into the threaded holes 276 of the connecting portions 270, 272, 274. There are any desired number of connecting portions 270, 272, 274. For example, exactly three connecting portions 270, 272, 274 are provided.

[0141] At the exterior, each connecting portion 270, 272, 274 has a cylindrical outer surface 278, as is shown on the basis of the connecting portion 274 in Figure 6. The outer surface 278 is adjoined by a cone surface 280. The cone surface 280 and the outer surface 278 serve for guiding and / or positioning the mounting element 208 on the temperature-regulating medium line connection 202A. For this purpose, the mounting element 208 has suitable receiving portions for receiving the connecting portions 270, 272, 274.

[0142] Each connecting portion 270, 272, 274 is connected to the connection portion 214 in one piece, in particular materially in one piece, with the aid of a bridge portion 282, 284, 286. The bridge portions 282, 284, 286 are elastically deformable. The temperature-regulating medium line connection 202A is preferably a one-piece component, in particular one which is materially in one piece.

[0143] Figure 7 shows a schematic plan view of a further embodiment of a temperatureregulating medium line connection 202B. Figure 8 shows a schematic perspective view of the temperature-regulating medium line connection 202B. Figure 9 shows a schematic sectional view of the temperature-regulating medium line connection 202B. Hereinafter, reference is made to Figures 7 to 9 concurrently.

[0144] In terms of its construction and its function, the temperature-regulating medium line connection 202B substantially corresponds to that of the temperature-regulating medium line connection 202A. Therefore, essentially only differences between the two embodiments of the temperature-regulating medium line connection 202A, 202B are discussed below.

[0145] The temperature-regulating medium line connection 202B comprises a connection portion 214 as mentioned above, which is constructed rotationally symmetrically with respect to a central axis 212, having an exterior sealing groove 216 for a seahng element 204 (not shown) as mentioned above and also a first outer surface 218 and a second outer surface 220. The connection portion 214 has a central perforation 222, which however has a cylindrical inner surface 224 rather than a conical inner surface. On the front side, a flange surface 226 as mentioned above is provided on the connection portion 214. Facing away from the flange surface 226, the connection portion 214 has an end face 228.

[0146] The temperature-regulating medium line connection 202B comprises a plurality of securing portions 230, 232, 234, 236, 238, 240 having adhesive bonding joints 242 (Figure 8) as mentioned above. The securing portions 230, 232, 234, 236, 238, 240 are secured to a ring-shaped carrying portion 288. The carrying portion 288 extends radially out from the connection portion 214 and is formed in one piece, in particular materially in one piece, therewith.

[0147] The securing portions 230, 232, 234, 236, 238, 240, as shown on the basis of the securing portion 230 in Figure 7, are mechanically decoupled from the carrying portion 288 with the aid of approximately ring-shaped cutouts 290, such that the securing portions 230, 234, 236, 238, 240 are each connected to the carrying portion 288 only with the aid of a decoupling structure 292 in the form of a bridge. Each securing portion 230, 232, 234, 236, 238, 240 has a central hole 294. Through the hole 294, adhesive for forming the adhesive bonding joints 242 can be guided to end faces 250 (Figure 9) of the securing portions 230, 234, 236, 238, 240.

[0148] Furthermore, the temperature-regulating medium line connection 202B comprises a plurality of connecting portions 270, 272, 274, which are likewise decoupled from the carrying portion 288 with the aid of approximately circular cutouts 296. With the aid of the cutouts 296, the connecting portions 270, 272, 274 are separated from the carrying portion 288 in such a way that they are connected to the carrying portion 288 only via a thin bridge portion 298, as is shown on the basis of the connecting portion 270 in Figure 7. Each connecting portion 270, 272, 274 comprises a central threaded hole 276 (Figure 7) as mentioned above for securing elements 210 (not shown) as mentioned above.

[0149] Figure 10 shows a schematic plan view of a further embodiment of a temperature-regulating medium line connection 202C. Figure 11 shows a schematic perspective view of the temperature-regulating medium line connection 202C. Figure 12 shows a schematic sectional view of the temperature-regulating medium line connection 202C. Hereinafter, reference is made to Figures 10 to 12 concurrently.

[0150] In terms of its construction and its functionality, the temperature-regulating medium line connection 202C substantially corresponds to that of the temperatureregulating medium line connection 202A. Therefore, essentially only differences between the two embodiments of the temperature-regulating medium line connection 202A, 202C are discussed below.

[0151] The temperature-regulating medium line connection 202C comprises a connection portion 214 as mentioned above, which is constructed rotationally symmetrically with respect to a central axis 212, having an outer sealing groove 216 for receiving a sealing element 204 (not shown) as mentioned above, a first outer surface 218 and a second outer surface 220. A central perforation 222 of the connection portion 214 has a conical inner surface 224 as mentioned above.

[0152] A flange surface 226 is provided on the connection portion 214 at the top side in the orientation in Figure 12. Facing away from the flange surface 226, the connection portion 214 has an end face 228. A cross-sectionally dovetail-shaped sealing groove 300 for receiving a sealing element 206 (not shown) as mentioned above is provided on the flange surface 226. The sealing groove 300 can be milled into the flange surface 226. An inner surface 302 extending around the central axis 212 is provided on the connection portion 214 in a manner set back relative to the flange surface 226.

[0153] The temperature-regulating medium line connection comprises a plurality of securing portions 230, 232, 234, 236, 238, 240 as mentioned above. Each securing portion 230, 232, 234, 236, 238, 240 is assigned an adhesive bonding joint 242 (Figure 11) as mentioned above. Each securing portion 230, 232, 234, 236, 238, 240 is perforated by a hole 304, as shown on the basis of the securing portion 230 in Figure 10. The hole 304 leads to the respective end face 250 (Figure 12) of the securing portions 230, 232, 234, 236, 238, 240 in order to introduce adhesive between the end faces 250 and the end face 126 of the decoupling pin 118 for the purpose of forming the adhesive bonding joints 242.

[0154] In contrast to the temperature-regulating medium line connection 200A, the securing portion 232 comprises a cylindrical receiving portion 306 having a larger diameter than the hole 304, and the securing portion 238 comprises an elongated- hole-shaped receiving portion 308. With the aid of the receiving portions 306, 308, the mounting element 208 (not shown) can be positioned on the temperature-regulating medium line connection 202C.

[0155] The securing portions 230, 232, 234, 236, 238, 240 are connected to the connection portion 214 with the aid of decoupling structures 252, 254, 256 as mentioned above. In this case, the decoupling structures 252, 254, 256 have first bridge portions 258, 260, 262 and also second bridge portions 264, 266, 268 as mentioned above.

[0156] The temperature-regulating medium line connection 202C furthermore comprises connecting portions 270, 272, 274 as mentioned above. Each connecting portion 270, 272, 274 has a central threaded hole 276 (Figure 10 and Figure 12). In contrast to the temperature-regulating medium line connection 202A, however, in this case the mounting element 208 (not shown) is not positioned at the connecting portions 270, 272, 274, but rather at the receiving portions 306, 308. For this reason, the connecting portions 270, 272, 274 also do not project beyond the securing portions 230, 232, 234, 236, 238, 240 as viewed along the central axis 212.

[0157] The connecting portions 270, 272, 274 are connected to the connection portion 214 with the aid of bridge portions 282, 284, 286 as mentioned above. In this case, however, the bridge portions 282, 284, 286 have perforations 310, 312, 314.

[0158] Figure 13 shows a schematic plan view of a further embodiment of a temperatureregulating medium line connection 202D. Figure 14 shows a schematic perspective view of the temperature-regulating medium line connection 202D. Figure 15 shows a schematic sectional view of the temperature-regulating medium line connection 202D. Hereinafter, reference is made to Figures 13 to 15 concurrently.

[0159] In terms of its construction, the temperature-regulating medium line connection 200D substantially corresponds to that of the temperature-regulating medium line connection 202A with the difference that the flange surface 226 of the temperatureregulating medium line connection 202A has a sealing groove 300 as mentioned above for receiving a sealing element 206 (not shown). Furthermore, an inner surface 302 as mentioned above is also provided.

[0160] In other words, the temperature-regulating medium line connection 202D comprises a connection portion 214 as mentioned above, which is constructed rotation- ally symmetrically with respect to a central axis 212, having a sealing groove 216 extending around the exterior, a first outer surface 218, a second outer surface 220 and a central perforation 222 with a conical inner surface 224. Facing away from the flange surface 226 with the seahng groove 300 and the inner surface 302, the connection portion has an end face 228.

[0161] Securing portions 230, 232, 234, 236, 238, 240 as mentioned above are arranged in a manner grouped around the connection portion 214. Each securing portion 230, 232, 234, 236, 238, 240 is assigned an adhesive bonding joint 242 (Figure 14). The securing portions 230, 232, 234, 236, 238, 240 each comprise a cylindrical outer surface 244 and a central perforation 246. The perforation 246 can merge into a hole 248 (Figure 6) not shown in Figure 15. The adhesive bonding joints 42 are provided on end faces 250 (Figure 15) of the securing portions 230, 232, 234, 236, 238, 240.

[0162] The securing portions 230, 232, 234, 236, 238, 240 are connected to the connection portion 214 with the aid of decoupling structures 252, 254, 256. Each decoupling structure 252, 254, 256 comprises a first bridge portion 258, 260, 262 and also a second bridge portion 264, 266, 268 connecting the respective first bridge portion 258, 260, 262 to the connection portion 214.

[0163] Furthermore, the temperature-regulating medium line connection 202D comprises connecting portions 270, 272, 274. The connecting portions 270, 272, 274 each have threaded holes 276 (Figure 13). Each connecting portion 270, 272, 274 comprises a cylindrical outer surface 278 and also a cone surface 280. It is thereby possible to position the mounting element 208 (not shown) on the connecting portions 270, 272, 274. The connecting portions 270, 272, 274 are connected to the connection portion 214 with the aid of bridge portions 282, 284, 286. Each bridge portion 282, 284, 286 is perforated with the aid of a perforation 310, 312, 314.

[0164] Figure 16 shows a schematic partial sectional view of a further embodiment of an optical system 100B.

[0165] The optical system 100B has an optical element 102B. The optical element 102B can be identical with the optical element 102 mentioned above. In comparison with the optical element 102A, however, the optical element 102B is thinner or flatter or has a smaller thickness.

[0166] The optical element 102B has a base body 116 and a decoupling pin 118 extending out from the base body 116. In particular, the decoupling pin 118 extends out from a surface 120 of the base body 116. The decoupling pin 118 is assigned a central axis 122 as mentioned above, but the decoupling pin 118 is not constructed rotationally symmetrically with respect to said axis. The decoupling pin 118 comprises an outer surface 124, the latter not being constructed rotationally symmetrically with respect to the central axis 122, but rather asymmetrically. In particular, the decoupling pin 118 has a cross-sectionally oval or rectangular shape with rounded corners. A temperature-regulating channel 108 as mentioned above runs through the decoupling pin 118, said channel being constructed rotationally symmetrically with respect to the central axis 122. The decoupling pin 118 comprises an end face 126. Within the decoupling pin 118, the temperature-regulating channel 108 widens to a recess 128. The temperature-regulating channel 108 merges into the recess 128 by way of a shoulder 130.

[0167] A connection system 400 is connected to the decoupling pin 118. The functionality of the connection system 400 substantially corresponds to that of the connection system 200. The connection system 400 is suitable for connecting a temperatureregulating medium line 114, as mentioned above, with a securing flange 132 to the optical element 102B. A temperature-regulating medium line connection 402A is provided for this purpose. The temperature-regulating medium line connection 402A is assigned two sealing elements 404, 406, in particular in the form of O- rings. A mounting element 408 is connected to the temperature-regulating medium line connection 402A with the aid of securing elements 410. The functionality of the mounting element 408 and of the securing elements 410 corresponds to that of the mounting element 208 and of the securing elements 210.

[0168] Figure 17 shows a schematic bottom view of a temperature-regulating medium line connection 402A as mentioned above. Figure 18 shows a schematic perspective view of the temperature-regulating medium line connection 402A. Figure 19 shows a schematic sectional view of the temperature-regulating medium line connection 402A. Hereinafter, reference is made to Figures 17 to 19 concurrently.

[0169] The temperature-regulating medium line connection 402A comprises an axis of symmetry or central axis 412. A connection portion 414 of the temperature-regulating medium line connection 402 A is constructed rotationally symmetrically with respect to the central axis 412. A sealing groove 416 is provided at the exterior of the connection portion 414, a sealing element 404 (not shown) as mentioned above being received in said sealing groove. At the exterior, the connection portion 414 has a first outer surface 418 and a second outer surface 420. In this case, the second outer surface 420 has a larger external diameter than the first outer surface 418. The connection portion 414 is centrally perforated by a perforation 222. The perforation 222 has a cylindrical inner surface 424 on the inside. A flange surface 426 is provided on the connection portion 414 at the top side in the orientation in Figure 19. A cross-sectionally dovetail-shaped sealing groove 428 for receiving a sealing element 406 (not shown) as mentioned above is incorporated into the flange surface 426. The sealing groove 428 runs as far as an inner surface 430 of the connection portion 414. Facing away from the flange surface 426 and the inner surface 430, the connection portion 414 has an end face 432.

[0170] The temperature-regulating medium line connection 402A comprises a plurality of securing portions 434, 436, 438, 440. The securing portion 434 has a recess 442. The recess 442 has the shape of an elongated hole. The securing portion 438 likewise has a recess 444. The recess 444 can be circular. With the aid of the recesses 442, 444, the mounting element 408 (not shown) can be positioned on the temperature-regulating medium line connection 402A.

[0171] The securing portions 436, 440 comprise central holes 446, 448. The recesses 442, 444 can also merge into such holes 446, 448. Through the holes 446, 448, adhesive can be applied to a respective end face 450 (Figure 19) of the securing portions 434, 436, 438, 440 in order to form adhesive bonding pads or adhesive bonding joints 452 (Figure 17).

[0172] The securing portions 434, 436, 438, 440 are connected to the connection portion 414 with the aid of decoupling structures 454, 456. In this context, each of the decoupling structures 454, 456 has a first bridge portion 458, 460 connecting in each case two of the securing portions 434, 436, 438, 440 to one another, and also a second bridge portion 462, 464 connecting the respective first bridge portion 458, 460 to the connection portion 414. The securing portions 434, 436, 438, 440 each have a cylindrical outer surface 466.

[0173] Furthermore, the temperature-regulating medium line connection 402A comprises two connecting portions 468, 470, which can be arranged opposite one another. Each connecting portion 468, 470 has a central threaded hole 472 and also a cylindrical outer surface 474 and a cone surface 476. With the aid of the outer surface 474 and the cone surface 476, the mounting element 408 is guided at the temperature-regulating medium line connection 402A. The connecting portions 468, 470 are connected to the connection portion 414 with the aid of bridge portions 478, 480. The bridge portions 478, 480 each have perforations 482, 484.

[0174] Figure 20 shows a schematic bottom view of a further embodiment of a temperature-regulating medium line connection 402B. Figure 21 shows a schematic perspective view of the temperature-regulating medium line connection 402B. Figure 22 shows a schematic sectional view of the temperature-regulating medium line connection 402B. Hereinafter, reference is made to Figures 20 to 22 concurrently.

[0175] In terms of its construction and its functionality, the temperature-regulating medium line connection 402B substantially corresponds to that of the temperatureregulating medium line connection 402A. Therefore, essentially only differences between the two embodiments of the temperature-regulating medium line connection 402A, 402B are discussed below.

[0176] The temperature-regulating medium line connection 402B comprises a connection portion 414 as mentioned above with an outer sealing groove 416. Furthermore, the connection portion 414 has a first outer surface 418 and a second outer surface 420. The outer surfaces 418, 420 have the same external diameter in this case. However, different external diameters can also be provided. A central perforation 422 comprises a cylindrical inner surface 424. At the top side, the connection portion 414 has a flange surface 426 with a sealing groove 428, and also an inner surface 430. Facing away from the flange surface 426 and the inner surface 430, an end face 432 is provided.

[0177] A plurality of securing portions 434, 436, 438, 440 as mentioned above are arranged in a manner grouped around the connection portion 414. The securing portion 434 has an elongated-hole-shaped recess 442, whereas the securing portion 438 has a cylindrical recess 444. The securing portions 436, 440 have holes 446, 448. The recesses 442, 444 can also merge into such holes 446, 448. The holes 446, 448 lead to respective end faces 450 (Figure 22) of the securing portions 434, 436, 438, 440. Adhesive bonding joints 452 (Figure 20) are provided at the end faces 450.

[0178] The securing portions 434, 436, 438, 440 are connected to the connection portion 414 with the aid of decoupling structures 454, 456. Each decoupling structure 454, 456 comprises a first bridge portion 458, 460 and also a second bridge portion 462, 464 connecting the respective first bridge portion 458, 460 to the connection portion 414. Each securing portion 434, 436, 438, 440 comprises a cylindrical outer surface 466.

[0179] Furthermore, the temperature-regulating medium line connection 402B comprises two connecting portions 468, 470, which each centrally have a threaded hole 472. The connecting portions 468, 470 have a cylindrical outer surface 474, but no cone surface 476. In this case, the alignment of the mounting element 408 (not shown) preferably takes place only at the recesses 442, 444. The connecting portions 468, 470 are connected to the connection portion 414 via bridge portions 478, 480. The bridge portions 478, 480 comprise perforations 482, 484.

[0180] Figure 23 shows a schematic bottom view of a further embodiment of a temperature-regulating medium line connection 402C. Figure 24 shows a schematic perspective view of the temperature-regulating medium line connection 402C. Figure 25 shows a schematic sectional view of the temperature-regulating medium line connection 402 C. Hereinafter, reference is made to Figures 23 to 25 concurrently.

[0181] In terms of its construction and its functionality, the temperature-regulating medium line connection 402C corresponds to that of the temperature-regulating medium line connection 402B. In contrast to the temperature-regulating medium line connection 402B, however, the temperature-regulating medium line connection 402C is provided with a smooth flange surface 426 without a sealing groove 428 and without an inner surface 430.

[0182] Figure 26 shows a schematic perspective view of a further embodiment of a temperature-regulating medium line connection 202E for the optical system 100A in accordance with Figure 3. Figure 27 shows a schematic sectional view of the temperature-regulating medium line connection 202E. Hereinafter, reference is made to Figures 3, 26 and 27 concurrently.

[0183] In terms of its construction, the temperature-regulating medium line connection 202E substantially corresponds to that of the temperature-regulating medium line connection 202A. Therefore, only differences between the two embodiments of the temperature-regulating medium line connection 202A, 202E are discussed below.

[0184] The optical system 100A in accordance with Figure 3 or the temperature-regulating device 110 in accordance with Figure 2 is intended to be able to be filled with the temperature-regulating medium K, which is water, within a specific time specification of, for example, less than three hours in accordance with customer specifications or, for example, less than two hours in accordance with internal specifications. Draining the temperature-regulating medium K and also drying are likewise intended to be able to be carried out within a specific time specification of, for example, less than three hours in accordance with customer specifications or, for example, less than two hours in accordance with internal specifications. That is to say that the temperature-regulating medium line connection 202E is intended to allow both filling and also emptying and drying in accordance with the aforementioned specifications. The temperature-regulating medium line connection 202E is intended to enable a bubble-free filling process, which means that a bubble radius is intended to be less than 0.1 mm. The temperature-regulating medium line connection 202E must enable emptying and also drying so that no temperature-regulating medium K remains in the temperature-regulating medium line connection 202E.

[0185] The temperature-regulating medium line connection 202E has substantially a cylindrical geometry. As shown in Figure 3, a radial gap is provided between the outer surface 218 and the recess 128. The radial gap forms a tubular or hollow- cylindrical volume. Furthermore, an axial gap is provided between the end face 228 and the shoulder 130. During filling with the temperature-regulating medium K, air bubbles may be captured in these gaps, and need to be removed before the EUV exposure. During emptying and drying, temperature-regulating medium K may be retained, which should be removed owing to the risk of corrosion. The temperature-regulating medium line connection 202E is now optimized to the effect that both filling and also emptying and drying are improved.

[0186] In order then to facilitate filling and emptying, the axial gap between the end face 228 and the shoulder 130 has a length 11 oriented along the central axis 122 of more than 0.2 mm. By way of example, a length of 0.2 mm, 0.3 mm or 0.5 mm can be provided. A length 12 between an edge of the sealing groove 216 that is closest to the end face 228 and the end face 228 is preferably approximately 16 mm.

[0187] The geometric design of the temperature-regulating medium line connection 202E and the recess 128 creates a volume in the form of the radial gap mentioned above, which volume is formed in particular by two coaxial cylinders. This volume defines a hydraulic resistance that counteracts a movement of a liquid, for example the temperature-regulating medium K, or a gas, for example air.

[0188] This hydraulic resistance can be reduced by the enlargement of the axial gap, such that the temperature-regulating medium K can easily flow through the temperature-regulating medium line connection 202E during the emptying and drying thereof. This can be carried out using the same pumping speed of the method as is possible without an optimized axial gap.

[0189] Given the same length 12 of 16 mm as mentioned above, the enlargement of the axial gap of more than 0.2 mm and not greater than 2 mm is not expected to increase turbulences of a fluid flow of the temperature-regulating medium K during the EUV exposure. This means that an increase in the 3o forces and thus a deterioration in the line of sight of the optical element 102A should not be expected.

[0190] Moreover, it is possible to reduce the length 12. By way of example, the length 12 can be reduced to less than 10 mm. The hydraulic resistance is drastically reduced by the reduction of the length 12 and, consequently, no air bubbles and water pockets arise when the same pre-filling and pumping conditions are used for the filling and drying process. The time expenditure for filling, emptying and drying is reduced by the reduction of a dead volume between the temperature-regulating medium line connection 202E and the optical element 102A. Less material is required for the temperature-regulating medium line connection 202E since the latter is shorter. This reduces the costs per item. The geometry remains substantially the same.

[0191] In addition - as shown in Figures 26 and 27 - the connection portion 214 can be provided with at least two bypass holes 486, only one of which is provided with a reference sign. The bypass holes 486 are oriented perpendicular to the central axis 212 and extend from the outer surface 218 as far as the inner surface 224, or vice versa. The bypass holes 486 can be referred to as bypass openings. By way of example, two, four, six or eight bypass holes 486 are provided, arranged in a manner distributed uniformly around the centre axis 212. However, there are any desired number of bypass holes 486. The bypass holes 486 have a diameter of 1 mm to 2 mm.

[0192] Included air bubbles of any size in the vicinity of the sealing groove 216 are flushed away during the pre-filling process, in particular during evacuation, through a bypass produced by the bypass holes 486. A time to reach a dried state of the temperature-regulating medium line connection 202E is expected to be considerably shortened as far as emptying and drying processes are concerned. This will reduce the costs for machine operation and increase the availability of the optical system 100A for a customer and in an end customer semiconductor factory in the case of exchange, repair or outage times.

[0193] The bypass holes 486 offer a flexible solution. The proposed solution includes the positioning of at least two bypass holes 486 of this type. However, the geometric design of the temperature-regulating medium line connection 202E makes it possible to include further bypass holes 486, if necessary. An angular position of the bypass holes 486 can be designed in such a way that three bypass holes 486 are arranged in an upper hemisphere and three bypass holes 486 are arranged in a lower hemisphere. In this case, the bypass holes 486 are arranged in a manner not uniformly spaced apart from one another. Rather, the bypass holes 486 are divided into two groups each having three bypass holes 486. The bypass holes 486 of a group are each uniformly spaced apart from one another.

[0194] If more than three bypass holes 486 are required, the diameter of the bypass holes 486 can be optimized so that the latter suit the design of the temperature-regulating medium line connection 202E, in particular with regard to an angular position of the bypass holes 486. A size, in particular the diameter, and a geometric shape, which need not necessarily be circular, of the bypass holes 486 can easily be integrated as necessary into a changed design of the temperature-regulating medium line connection 202E.

[0195] The bypass holes 486 are also applicable to all other embodiments of the temperature-regulating medium line connection 202A, 202B, 202C, 202D, 402A, 402B, 402C.

[0196] Figure 28 shows a schematic perspective view of a further embodiment of a temperature-regulating medium line connection 202F for the optical system 100A in accordance with Figure 3. Figure 29 shows a schematic sectional view of the temperature-regulating medium line connection 202F. Hereinafter, reference is made to figures 28 and 29 concurrently.

[0197] The temperature-regulating medium line connection 202F differs from the temperature-regulating medium line connection 202E only in that the temperature -regulating medium line connection 202F does not have circular bypass holes 486 in its connection portion 214, but rather bypass perforations 488, which can be formed by a modification of the bypass holes 486. All previous explanations concerning the bypass holes 486 are accordingly also applicable to the bypass perforations 488.

[0198] The bypass perforations 488 can also be referred to as bypass openings. Each bypass perforation 488 has a bypass hole 486 as mentioned above, from which a slot 490 extending in the direction of the end face 228 extends. The slot 490 is conical in this case and tapers in the direction towards the end face 228. The slot 490 can also be rectangular. The bypass hole 486, prior to expanding to the respective bypass perforation 488, has a diameter of 1 mm to 2 mm. A length of the slot 490 along the central axis 212 amounts to one third of the length 12, i.e. 12 / 3. A width of the slot 490 is preferably a maximum of 1 mm. The bypass perforations 488, as explained above with reference to the bypass holes 486, can be positioned in any desired way at the connection portion 214. In particular, a division into two hemispheres is also possible. The bypass perforations 488 can be diametrically opposite one another.

[0199] Included air bubbles of any size in the vicinity of the sealing groove 216 and along the temperature-regulating medium line connection 202F are flushed away during the pre-filling process, in particular during evacuation, through the bypass perforations 488. With regard to the emptying and drying processes, the time to reach a dried state of the temperature-regulating medium line connection 202F is expected to be considerably reduced. The machine operating costs are reduced and the availability of the optical system 100A for the customer and in the end customer factory is increased during exchange, repair and outage times.

[0200] The bypass perforations 488 offer a flexible solution. The proposed solution includes the positioning of at least two bypass perforations 488. However, the geometric design of the temperature-regulating medium line connection 202F allows more bypass perforations 488 to be positioned, as necessary. If more than three bypass perforations 488 are required, the size of the diameter and the geometric shape of the bypass holes 486, which need not necessarily be circular, can be optimized so that these suit any desired design of the temperature-regulating medium line connection 202F, in particular with regard to the angular position. The slot 490 should then be correspondingly adapted.

[0201] The bypass perforations 488 are also applicable to all other embodiments of the temperature-regulating medium line connection 202A, 202B, 202C, 202D, 402A, 402B, 402C.

[0202] Figure 30 shows a schematic perspective sectional view of a further embodiment of a temperature-regulating medium line connection 202G for the optical system lOOAin accordance with Figure 3. Figures 31 and 32 each show a further schematic sectional view of the optical system 100A. Hereinafter, reference is made to Figures 30 to 31 concurrently.

[0203] In terms of its construction, the temperature-regulating medium line connection 202G substantially corresponds to that of the temperature-regulating medium line connection 202E. Therefore, only differences between the two embodiments of the temperature-regulating medium line connection 202E, 202G are discussed below.

[0204] In contrast to the temperature-regulating medium line connection 202E, the temperature-regulating medium line connection 202G does not have bypass holes 486 arranged perpendicular to the central axis 212, but rather obliquely oriented bypass holes 492, only one of which is provided with a reference sign. By way of example, it is possible to provide two, four or eight bypass holes 492 arranged diametrically opposite one another. The bypass holes 492 are arranged for example in a manner distributed uniformly around the central axis 212. The bypass holes 492 extend from a shoulder 494 of the perforation 222 in the direction of the outer surface 218 through the connection portion 214.

[0205] The aim of the design of the temperature-regulating medium line connection 202G is for a flow in the radial gap between the outer surface 218 and the recess 128 to correspond to a main flow direction 496, 498 shown in Figures 31 and 32. This reduces the risk of corrosion as a result of a faster and more complete draining process, since the temperature-regulating medium K is not led back into the radial gap.

[0206] Consequently, the radial gap is enabled to be filled and emptied in the same direction as the main flow direction 496, 498 by virtue of at least two inclined bypass holes 492 enabling flow through the radial gap. In this case, the bypass holes 492 have to be diametrically opposite one another. This maximizes an inflow area in the radial gap. Furthermore, one of the bypass holes 492 can be arranged on the underside if the temperature-regulating medium line connection 202G is installed horizontally. This prevents an accumulation of liquid caused by gravity, in particular a dead zone.

[0207] The bypass holes 492 are oriented at an acute angle with respect to the main flow direction 496, 498, as a result of which flow turbulences are minimized. The shoulder 494 forms a stepped flow delimitation on an inlet side of the bypass holes 492, as a result of which a pressure zone is enlarged.

[0208] The shoulder 494 is intended to act as a throttle in order to minimally increase a pressure pA in a region of a hole intake of bypass holes 492 when the temperatureregulating medium K flows in the main flow direction 496. This additional pressure pA is intended to overcome a higher pressure pB caused by the conical design. In the main flow direction 498, the pressure pA remains lower than the pressure pB on account of the smaller flow cross section. The bypass holes 492 are intended to prevent stagnant temperature-regulating medium K in the radial gap, which as is known may increase the risk of corrosion. By virtue of a minimum liquid flow through the radial gap being made possible uniformly and an oxygen gradient being maintained, gap -caused corrosion can be prevented. This is indicated in Figures 31 and 32 with the aid of arrows 500, 502, only one of which in each case is provided with a reference sign.

[0209] The design of the bypass holes 492 can be used in all other embodiments of the temperature-regulating medium line connection 202A, 202B, 202C, 202D, 202E, 202F, 402A, 402B, 402C, in particular having a conical channel design, with corrosion risks and is not restricted to EUV or even lithography applications. The main function of the design is to shorten the filling and emptying time and thus to reduce the risk of gap corrosion. Furthermore, additional measures are taken to reduce flow induced vibrations.

[0210] Figure 33 shows a schematic perspective sectional view of a further embodiment of a temperature-regulating medium line connection 202H.

[0211] In terms of its construction, the temperature-regulating medium line connection 202H substantially corresponds to that of the temperature-regulating medium line connection 202G with the difference that the temperature-regulating medium line connection 202G comprises, at the bypass holes 492, interior flow capture bumps 504 and also additional outlet holes 506 arranged in a manner inclined obliquely with respect to the central axis 212.

[0212] These flow capture bumps 504 can reduce the outflow in the radial gap and reduce the space requirement for the outflow delimitation. Together with the additional outlet holes 506, the risk of flow induced vibrations can be significantly reduced.

[0213] Although the present invention has been described on the basis of exemplary embodiments, it is modifiable in diverse ways. LIST OF REFERENCE SIGNS

[0214] 1 Projection exposure apparatus

[0215] 2 Illumination system

[0216] 3 Light source

[0217] 4 Illumination optical unit

[0218] 5 Object field

[0219] 6 Object plane

[0220] 7 Reticle

[0221] 8 Reticle holder

[0222] 9 Reticle displacement drive

[0223] 10 Projection optical unit

[0224] 11 Image field

[0225] 12 Image plane

[0226] 13 Wafer

[0227] 14 Wafer holder

[0228] 15 Wafer displacement drive

[0229] 16 Illumination radiation

[0230] 17 Collector

[0231] 18 Intermediate focal plane

[0232] 19 Deflection mirror

[0233] 20 First facet mirror

[0234] 21 First facet

[0235] 22 Second facet mirror

[0236] 23 Second facet

[0237] 100 Optical system

[0238] 100A Optical system

[0239] 100B Optical system

[0240] 102 Optical element

[0241] 102A Optical element

[0242] 102B Optical element

[0243] 104 Substrate

[0244] 106 Optically effective surface

[0245] 108 Temperature-regulating channel

[0246] 110 Temperature-regulating device

[0247] 112 Pump

[0248] 114 Temperature-regulating medium line

[0249] 116 Base body

[0250] 118 Decoupling pin

[0251] 120 Surface 122 Central axis

[0252] 124 Outer surface

[0253] 126 End face

[0254] 128 Recess

[0255] 130 Shoulder

[0256] 132 Securing flange

[0257] 200 Connection system

[0258] 202A Temperature-regulating medium line connection 202B Temperature-regulating medium line connection 202C Temperature-regulating medium line connection 202D Temperature-regulating medium line connection 202E Temperature-regulating medium line connection 202F Temperature-regulating medium line connection 202G Temperature-regulating medium line connection

[0259] 202H Temperature-regulating medium line connection 204 Sealing element 206 Sealing element

[0260] 208 Mounting element

[0261] 210 Securing element

[0262] 212 Central axis

[0263] 214 Connection portion

[0264] 216 Sealing groove

[0265] 218 Outer surface

[0266] 220 Outer surface

[0267] 222 Perforation

[0268] 224 Inner surface

[0269] 226 Flange surface

[0270] 228 End face

[0271] 230 S ecurin g p or tion

[0272] 232 S ecurin g p or tion

[0273] 234 S ecurin g p or tion

[0274] 236 S ecurin g p or tion

[0275] 238 S ecurin g p or tion

[0276] 240 Securing portion

[0277] 242 Adhesive bonding joint

[0278] 244 Outer surface

[0279] 246 Perforation

[0280] 248 Hole

[0281] 250 End face

[0282] 252 Decoupling structure 254 Decoupling structure

[0283] 256 Decoupling structure

[0284] 258 Bridge portion

[0285] 260 Bridge portion

[0286] 262 Bridge portion

[0287] 264 Bridge portion

[0288] 266 Bridge portion

[0289] 268 Bridge portion

[0290] 270 Connecting portion

[0291] 272 Connecting portion

[0292] 274 Connecting portion

[0293] 276 Threaded hole

[0294] 278 Outer surface

[0295] 280 Cone surface

[0296] 282 Bridge portion

[0297] 284 Bridge portion

[0298] 286 Bridge portion

[0299] 288 Carrying portion

[0300] 290 Cutout

[0301] 292 Decoupling structure

[0302] 294 Hole

[0303] 296 Cutout

[0304] 298 Bridge portion

[0305] 300 Seahng groove

[0306] 302 Inner surface

[0307] 304 Hole

[0308] 306 Receiving portion

[0309] 308 Receiving portion

[0310] 310 Perforation

[0311] 312 Perforation

[0312] 314 Perforation

[0313] 400 Connection system

[0314] 402A Temperature-regulating medium line connection

[0315] 402B Temperature-regulating medium line connection

[0316] 402C Temperature-regulating medium line connection

[0317] 404 Seahng element

[0318] 406 Seahng element

[0319] 408 Mounting element

[0320] 410 Securing element

[0321] 412 Central axis 414 Connection portion

[0322] 416 Sealing groove

[0323] 418 Outer surface

[0324] 420 Outer surface

[0325] 422 Perforation

[0326] 424 Inner surface

[0327] 426 Flange surface

[0328] 428 Sealing groove

[0329] 430 Inner surface

[0330] 432 End face

[0331] 434 Securing portion

[0332] 436 Securing portion

[0333] 438 Securing portion

[0334] 440 Securing portion

[0335] 442 Recess

[0336] 444 Recess

[0337] 446 Hole

[0338] 448 Hole

[0339] 450 End face

[0340] 452 Adhesive bonding joint

[0341] 454 Decoupling structure

[0342] 456 Decoupling structure

[0343] 458 Bridge portion

[0344] 460 Bridge portion

[0345] 462 Bridge portion

[0346] 464 Bridge portion

[0347] 466 Outer surface

[0348] 468 Connecting portion

[0349] 470 Connecting portion

[0350] 472 Threaded hole

[0351] 474 Outer surface

[0352] 476 Cone surface

[0353] 478 Bridge portion

[0354] 480 Bridge portion

[0355] 482 Perforation

[0356] 484 Perforation

[0357] 486 Bypass hole

[0358] 488 Bypass perforation

[0359] 490 Slot

[0360] 492 Bypass hole 494 Shoulder

[0361] 496 Main flow direction

[0362] 498 Main flow direction

[0363] 500 Arrow

[0364] 502 Arrow

[0365] 504 Flow capture bump

[0366] 506 Outlet hole

[0367] K Temperature-regulating medium

[0368] 11 Length

[0369] 12 Length

[0370] Ml Mirror

[0371] M2 Mirror

[0372] M3 Mirror

[0373] M4 Mirror

[0374] M5 Mirror

[0375] M6 Mirror pA Pressure pB Pressure

[0376] Q Heat x x- direction y y- direction z z- direction

Claims

PATENT CLAIMS1. Optical system (100, 100A, 100B) for a projection exposure apparatus (1), having an optical element (102, 102A, 102B), and a temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 202G, 202H, 402A, 402B, 402C) attached to the optical element (102, 102A, 102B) and serving for connecting a temperature-regulating medium line (114) to the optical element, wherein the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 202G, 202H, 402A, 402B, 402C) has a connection portion (214, 414), through which a temperature-regulating medium (K) is guidable, wherein the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 202G, 202H, 402A, 402B, 402C) has a securing portion (230, 232, 234, 236, 238, 240, 434, 436, 438, 440), which is connected to the optical element (102, 102A, 102B), and wherein the connection portion (214, 414) is mechanically decoupled from the securing portion (230, 232, 234, 236, 238, 240, 434, 436, 438, 440).

2. Optical system according to Claim 1, wherein the connection portion (214, 414) is arranged at least partly within the optical element (102, 102A, 102B), and wherein the securing portion (230, 232, 234, 236, 238, 240, 434, 436, 438, 440) is arranged outside the optical element (102, 102A, 102B).

3. Optical system according to Claim 1 or 2, wherein the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 402A, 402B, 402C) has a plurality of securing portions (230, 232, 234, 236, 238, 240, 434, 436, 438, 440) arranged in distributed fashion around the connection portion (214, 414).

4. Optical system according to Claim 3, wherein the connection portion (214, 414) mechanically decouples from the securing portions (230, 232, 234, 236, 238, 240, 434, 436, 438, 440) with the aid of elastically deformable decoupling structures (252, 254, 256, 292, 454, 456).

5. Optical system according to Claim 4, wherein each decoup ling structure (252, 254, 256, 454, 456) has an elastically deformable first bridge portion (258, 260, 262, 458, 460) connecting two securing portions (230, 232, 234, 236, 238, 240, 434, 436, 438, 440) to one another, and an elastically deformable secondbridge portion (264, 266, 268, 462, 464) connecting the first bridge portion (258, 260, 262, 458, 460) and the connection portion (214, 414) to one another.

6. Optical system according to any of Claims 1 - 5, wherein the connection portion (214, 414) has a perforation (222, 422), through which the temperatureregulating medium (K) is guidable, and wherein the perforation (222) preferably has an at least partly frustoconical inner surface (224).

7. Optical system according to any of Claims 1 - 6, wherein the connection portion (214, 414) has a sealing groove (216, 416) for receiving a sealing element (204, 404), which seals the connection portion (214, 414) vis-a-vis the optical element (102, 102A, 102B).

8. Optical system according to any of Claims 1 - 7, wherein the temperatureregulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 402A, 402B, 402C) has a connecting portion (270, 272, 274, 468, 470) for connecting the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 402A, 402B, 402C) to a mounting element (208, 408), wherein the connecting portion (270, 272, 274, 468, 470) is connected to the connection portion (214, 414) with the aid of a bridge portion (282, 284, 286, 478, 480), and wherein a securing flange (132) of the temperature-regulating medium line (114) is arrangeable between the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 402A, 402B, 402C) and the mounting element (208, 408).

9. Optical system according to Claim 8, wherein the connecting portion (270, 272, 274, 468, 470) is cylindrical, and wherein the connecting portion (270, 272, 274, 468, 470) has a threaded hole (276, 472).

10. Optical system according to any of Claims 1 - 9, wherein the temperatureregulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 402A, 402B, 402C) has a flange surface (226, 426) facing away from the optical element (102, 102A, 102B).

11. Optical system according to any of Claims 1 - 10, wherein the optical element (102, 102A, 102B) has a base body (116) and a decoupling pin (118) extending out from the base body (116), and wherein the temperature-regulating medium line connection (202A, 202B, 202C, 202D, 202E, 202F, 402A, 402B, 402C) is attached to the decoupling pin (118).

12. Optical system according to Claim 11, wherein the decoupling pin (118) has a temperature-regulating channel (108) constructed rotationally symmetrically with respect to a central axis (122), wherein the decoupling pin (118) is constructed asymmetrically with respect to the central axis (122), wherein the decoupling pin (118) is preferably oval in cross section, and wherein the temperatureregulating medium line connection (402A, 402B, 402C) is preferably constructed asymmetrically with respect to the central axis (122).

13. Optical system according to any of Claims 1 - 12, wherein the connection portion (214) has bypass holes (486, 492) and / or bypass perforations (488) extending from an inner surface (224) of the connection portion (214) to an outer surface (218) of the connection portion (214), and wherein the bypass holes (492) are arranged in particular obliquely with respect to a central axis (212) of the connection portion (214).

14. Optical system according to any of Claims 1 - 13, wherein the securing portion (230, 232, 234, 236, 238, 240, 434, 436, 438, 440), facing the optical element (102, 102A, 102B), has an adhesive bonding joint (242, 452), with the aid of which the securing portion (230, 232, 234, 236, 238, 240, 434, 436, 438, 440) is adhesively bonded to the optical element (102, 102A, 102B).

15. Projection exposure apparatus (1) comprising an optical system (100, 100A, 100B) according to any of Claims 1 - 14.

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