Mirror setup

Abstract

Mirror device (24), comprising a mirror (25), with a mirror body (26) having a reflective surface (27) and at least one side surface (27) and at least one mirror body transition area (29) arranged on the side surface (28) of the mirror body (26), at least one receptacle (30) arranged in the mirror body transition area (29), at least one fastening component (31) arranged in the at least one receptacle (30) and at least one connecting body (32) for attaching at least one functional component (34) to the mirror (25), wherein the connecting body (32) is attached to the at least one fastening component (31) by means of at least one fastening element (33), wherein by means of the fastening of the connecting body (32) a fastening component (31) of the connecting body (32) is attached to the mirror (25).

Description

[0001] The present invention relates to a mirror device with a connecting body for attaching additional functional components. Furthermore, the invention relates to an optical system with such a mirror device and a projection exposure system with such an optical system.

[0002] Mirror devices and the functional components attached to them are known from prior use.

[0003] It is an object of the invention to provide a mirror device to which additional functional components can be securely and easily attached.

[0004] This object is achieved according to the invention by a mirror device having the features mentioned in claim 1.

[0005] The mirror can, in particular, be a field facet module. It is also possible for the mirror to be a pupil facet module. The mirror can, in particular, be a grazing incidence mirror (GI mirror) of a corresponding mirror module (GMM). Such a GMM is used, for example, in the illumination optics of projection exposure systems for EUV lithography.

[0006] The side surfaces of the mirror base body can adjoin the reflective surface of the mirror base body. In particular, the side surfaces are not arranged opposite the reflective surface. At least one of the side surfaces has the transition region with the receptacle for the fastening component. The side surface with the transition region can also have several such transition regions. It is also possible for two, three, four, or even more side surfaces of the mirror base body to have at least one such transition region. In particular, it is also possible for the side opposite the reflective surface to have the transition region.

[0007] The mirror can be designed as a round body. The mirror can be designed, for example, as a conical or cylindrical body. It is also possible to design the mirror as part, particularly as half, of a sphere or a general solid of revolution, for example, an ellipsoid of revolution, a paraboloid of revolution, or a hyperboloid of revolution.

[0008] The mirror can also be designed as a straight body. A straight body is understood to be a geometric figure with a base and a top surface, where the base and top surfaces are congruent and parallel to each other. The base and top surfaces can, in particular, be designed as regular polygons. This makes it possible, for example, to design the mirror as a cuboid-shaped body.

[0009] With such a mirror design, the reflecting surface is the cross-sectional area of ​​the corresponding body. The reflecting surface can be a flat surface. A flat surface is understood, in particular, to be a surface whose principal curvature is 0 across its entire surface. It is also possible for the reflecting surface to be curved.

[0010] The mirror can have a central axis, which can in particular be aligned perpendicular to the reflecting surface of the mirror. The central axis can be an axis of symmetry of the mirror. The central axis can in particular be an axis of rotational symmetry of the mirror. It is also possible for the mirror to have integer rotational symmetry. Mirror designs without inherent symmetries are also possible.

[0011] The extent of the mirror orthogonal to the central axis is called the radius of the mirror. In particular, the radius of the mirror cannot be constant. In a non-rotationally symmetrical mirror design, the radius cannot be constant, especially within a plane perpendicular to the central axis.

[0012] The transition areas can extend radially and / or axially beyond the mirror base body, i.e., in particular, away from the central axis. The transition areas can abut the side surfaces of the mirror base body. In this case, it is particularly possible for the mirror base body and the transition areas to be formed as a single piece. Separate formation of the transition areas and subsequent attachment of the transition areas to the mirror base body is also possible. For this purpose, the transition areas can be attached to the mirror base body, for example, by means of a positive plug connection or by means of a material connection such as gluing and / or welding.

[0013] The transition areas have at least one receptacle, preferably at least two receptacles. The receptacles can be oriented parallel to the center axis of the mirror. It is also possible for the receptacles to be oriented perpendicular to the plane defined by the center axis and the radial direction.

[0014] It is possible for a side surface of the respective transition region, in particular the side surface whose surface normal is directed away from the mirror, to have a plurality of through-openings extending in the radial direction. In particular, it is possible for one and in particular two openings, which can be configured in particular as through-openings, to be located in the region of the geometric centroid of the side surface of the transition region. These openings can, in particular, protrude into the mirror base body.

[0015] It is also possible for at least one, in particular at least two, in particular at least three, and in particular at least four further openings to be arranged uniformly around the geometric centroid of the side surface of the transition region. These further through openings can, in particular, have a smaller diameter than the openings in the region of the geometric centroid. These further openings can, in particular, open into the receptacles.

[0016] It's possible that the receptacles are designed as blind holes, meaning they don't form any passages through the transition areas. It's also possible that the receptacles form passages through the transition area.

[0017] At least one fastening component is arranged in each of the receptacles of the transition area. The fastening component can be a metallic component whose shape is congruent with the shape of the receptacle. The fastening components can be made of stainless steel or aluminum, for example. It is also possible to manufacture the fastening components from other metals.

[0018] The fastening components can be held in the receptacles with a positive fit. The shape of the fastening components is matched to the shape of the receptacles in such a way that the fastening components are clamped into the receptacle when inserted, thereby securing it. If the receptacles are designed as blind holes, the fastening components are additionally held by the bottom of the respective blind hole.

[0019] It is also possible for the fastening components to be secured in the receptacles using a material-to-material connection. For example, it is possible for the fastening components to be glued into the receptacles.

[0020] It is also possible for the fastening components to be loosely arranged in the mount, i.e., to have degrees of freedom of movement, particularly along the entire length of the mount. In such a case, the fastening components are fixed in their respective mounts by attaching the connecting body to the mirror.

[0021] The fastening components themselves can have at least one, in particular at least two, in particular at least three and in particular at least four receptacles for receiving the fastening elements with which the connecting body is fastened to the mirror.

[0022] In particular, it is also possible for the fastening components and the connecting body to be formed monolithically as one component.

[0023] The fastening elements can be, for example, screws, bolts, or rivets, with which the connecting body can be non-positively attached to the mirror. It is possible for each of the fastening components to be designed to accommodate more than one fastening element. In particular, it is possible for one fastening component to be designed to accommodate two, in particular three, and in particular four fastening elements.

[0024] The connecting body can be designed as a flange. The connecting body is designed to create a tight connection between an additional functional component and the mirror. The leakage rate of the connection should, in particular, be no more than 10 -5 mbar · l / s, especially maximum 10-6 mbar l / s, in particular not more than 10 -7 mbar · l / s, in particular not more than 10 -8 mbar · l / s and in particular not more than 10 -9 mbar · l / s.

[0025] The connecting body can in particular also be designed to statically support the mirror.

[0026] The connecting body can have a plurality of through-openings. All but one, in particular two, of these through-openings can be identically designed. These identically designed through-openings can serve to pass through the fastening elements with which the connecting body is attached to the mirror.

[0027] The designated through openings can be arranged, in particular, in the area of ​​the geometric center of gravity of the connecting body. Said opening can, in particular, have a larger diameter than the plurality of identical openings for the fastening elements.

[0028] The openings of the connecting body can in particular be designed such that they coincide with the openings of the transition region already described.

[0029] Such a mirror assembly enables the particularly simple and secure, particularly sealing, attachment of functional components to the mirror. Because the fastening elements are not directly embedded in the mirror body, the connection can be realized in a way that is particularly gentle on the mirror material.

[0030] Any tensile, shear, or compressive forces transmitted via the fastening elements cannot place stress on the mirror base. This makes the mirror base particularly durable.

[0031] By reducing the mechanical stress on the base body when attaching the connecting body to the mirror base body, the risk of damaging the mirror base body can be minimized. Overall, stresses that could be critical to the mirror base body can be reduced. This significantly increases the initial yield, i.e., the number of components that do not require rework.

[0032] A mirror device according to claim 2 is easy to handle. Because the fastening elements and fastening components each have matching thread types, fastening the connecting body is particularly simple. The force required to insert the fastening elements into the fastening components can be reduced. This allows production or maintenance personnel to work faster, while maintaining the same level of precision, and the work can be carried out more smoothly.

[0033] The external and / or internal threads can be metric ISO threads. The threads can also be trapezoidal threads.

[0034] A mirror device according to claim 3 can be effectively used as an assembly for the optics of a projection exposure system for lithography. Mirror devices, in particular field facet modules, pupil facet modules, and / or GI mirrors, are predominantly used in EUV and DUV lithography. For wavelengths in the EUV or DUV range, such mirrors have a relatively large absorption coefficient. Accordingly, the mirrors will heat up over time. By using internal cooling channels, the heat generated by the absorption of EUV or DUV photons can be dissipated. This makes it possible for the mirror to remain in use particularly efficiently and for a long time. Damage and / or complete destruction of the mirror or mirror surface due to the absorbed heat can also be prevented by means of internal cooling channels.

[0035] The internal cooling channels may have a surface that is, in particular, smooth. A smooth surface is understood to mean a surface of the internal cooling channels that is free of edges and / or kinks. In particular, the term "smooth" should also be understood as continuously variable.

[0036] The internal cooling channel can be connected to the connecting body, in particular to the one through-hole in the connecting body. This allows coolant to be introduced into the internal cooling channels.

[0037] It is possible for the internal cooling channel to form a closed loop. This means that the fluid inflow of the internal cooling channel and the fluid outflow of the internal cooling channel are connected to the same connecting body.

[0038] It is also possible that the fluid inflow of the internal cooling channel and the fluid outflow of the internal cooling channel are connected to different connecting bodies.

[0039] It is also possible for the mirror base body to have more than one internal cooling channel. In this case, each of the internal cooling channels can be designed to cool a predefined area of ​​the mirror base body. This allows individual areas of the mirror base body to be cooled more efficiently.

[0040] It is possible for the mirror base body to have at least two, in particular at least three, in particular at least four, in particular at least five, in particular at least six, in particular at least seven, and in particular at least eight internal cooling channels. The cooling channels do not have to be identical. It is particularly possible for individual cooling channels to be looped, while other cooling channels are continuous.

[0041] A mirror device according to claim 4 results in particularly efficient and uniform cooling of the mirror base body. In particular, the cross-section of the internal cooling channels remains constant even in the event of channel direction changes. The constant flow cross-section allows local flow separation and thus local turbulence to be reduced and, in particular, avoided. In principle, internal cooling channels of the mirror base body can also be designed with a non-constant cross-section.

[0042] Turbulent flows lead to increased internal flow resistance. As a result, the coolant can no longer flow efficiently through the cooling channels. This can negatively impact cooling, especially at low flow velocities. This effect can be reliably avoided by maintaining a constant cross-section of the internal cooling channels.

[0043] A mirror device according to claim 5 is particularly simple and efficient to operate. By connecting a coolant line to the mirror base body via the connecting body, a uniform and continuous fluid flow can be ensured. Connections for connecting the respective coolant line to the mirror base body can each have a flange. A sealing element can be used to tightly attach such a flange. Such a sealing element can be designed as a molded seal, particularly attached internally to the respective cooling channel, and / or as an O-ring, particularly attached externally.

[0044] In particular, it eliminates the need to constantly refill any fluid reservoir. Connecting the mirror base to a fluid line ensures that coolant is available indefinitely when the mirror is in use. In particular, this avoids having to interrupt the use of the mirror to refill a fluid reservoir.

[0045] Water is a preferred coolant. Other coolants that can efficiently dissipate heat are also possible.

[0046] In particular, it is also possible to use liquefied gases, such as liquid nitrogen or liquid oxygen, to cool the mirror base body.

[0047] A mirror device with a Reynolds number of 2300 or less effectively prevents turbulent flow. The Reynolds number is a dimensionless quantity that depends on the fluid density, the fluid flow velocity, and the characteristic lengths of the body through which the fluid flows. The fluid density and flow velocity can be adjusted via the coolant line. These quantities should be adjusted so that the internal cooling channels have a Reynolds number of 4000 or less, in particular 3000 or less, in particular 2500 or less, in particular 2300 or less, in particular 2000 or less, and in particular 1900 or less.

[0048] It has been experimentally confirmed several times that a Reynolds number of 2300 represents the limit for the development of turbulent flows. By using a corresponding Reynolds number, turbulent flows can be further efficiently avoided inside the cooling channels of the mirror body.

[0049] This not only ensures more efficient and uniform cooling, but also effectively prevents fluid-induced vibrations by avoiding turbulent flows. These fluid-induced vibrations can impair the performance of the mirror and, in extreme cases, even damage and / or destroy it.

[0050] In particular, it has been shown that even cooling channels with Reynolds numbers above 2300 can be used efficiently to cool mirror devices. In this case, slightly turbulent flows are deliberately induced, at least in certain areas, to improve cooling performance.

[0051] A mirror device according to claim 6 is particularly easy to manufacture. The mirror can be formed at least partially from silicon, in particular monocrystalline silicon and / or ceramic and / or glass ceramic.

[0052] It is also possible to make the mirror, and in particular the mirror base, from a brittle metal.

[0053] A mirror device according to claim 7 is particularly durable. The contact pressure with which the connecting body is fastened to the mirror should be at most 20 MPa, in particular at most 18 MPa, in particular at most 16 MPa, in particular at most 14 MPa, in particular at most 12 MPa, in particular at most 10 MPa, in particular at most 9 MPa, in particular at most 8 MPa, in particular at most 7 MPa, in particular at most 6 MPa, and in particular at most 5 MPa. The same applies to the contact pressure of the respective fastening component or functional component on the mirror. Corresponding contact pressure values ​​can apply to all load cases of such fastenings, in particular in connection with forces that occur during assembly of the connecting bodies or flanges, as well as for contact pressure values ​​that occur under the influence of external loads.

[0054] Appropriate contact pressure ensures that the connecting body is securely, stably, and firmly attached to the mirror, while also keeping the mechanical stress on the mirror to a minimum, allowing the mirror to last a particularly long time. The design of the connecting body, flange, and fastening elements can also prevent stress peaks (line or point contacts).

[0055] The contact pressure can be exerted on the mirror via the connecting body and the receptacle for the at least one fastening component.

[0056] Further objects of the invention are to improve an optical system and a projection exposure apparatus.

[0057] These objects are achieved by an optical system having the features set forth in claims 8 and 9, respectively, and a projection exposure system having the features set forth in claim 10. The optical system according to claim 8 can be an illumination optical system and / or a projection optical system.

[0058] The projection exposure system can be used to produce a microchip made of semiconductor material, in particular a memory chip or a logic chip. Such a semiconductor component, which can be produced with the projection exposure system, can have micro- or nanostructures.

[0059] The advantages of the optical system or the projection exposure system correspond to those already explained with reference to the mirror device.

[0060] Embodiments of the invention are explained in more detail below with reference to the figures. They show: Fig. 1 schematically shows in meridional section a projection exposure system for EUV projection lithography, Fig. 2 a mirror device in which the connecting body and the functional component are attached to the mirror, Fig. 3 Mirror device in top view, and Fig. 4 Enlarged cross-sectional view of the transition area.

[0061] In the following, with reference to the Fig. 1 describes, by way of example, the essential components of a projection exposure system 1 for microlithography. The description of the basic structure of the projection exposure system 1 and its components is not intended to be limiting.

[0062] One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optics 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 separate module from the rest of the illumination system. In this case, the illumination system does not include the light source 3.

[0063] 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 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9.

[0064] In the Fig. 1 shows a Cartesian xyz coordinate system for explanation. The x-direction is perpendicular to the plane of the drawing. The y-direction is horizontal and the z-direction is vertical. The scanning direction is in the Fig. 1 along the y-direction. The z-direction runs perpendicular to the object plane 6.

[0065] The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image 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 other than 0° between the object plane 6 and the image plane 12 is also possible.

[0066] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0067] Radiation source 3 is an EUV radiation source. Radiation source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation or illumination radiation. The useful radiation has, in particular, a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be a plasma source, for example, an LPP source (laser produced plasma) or a DPP source (gas discharged produced plasma). It can also be a synchrotron-based radiation source. Radiation source 3 can be a free-electron laser (FEL).

[0068] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (GI), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0069] After 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 radiation source 3 and the collector 17, and the illumination optics 4.

[0070] The illumination optics 4 comprises a first facet mirror 19. If the first facet mirror 19 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6, it is also referred to as a field facet mirror. The first facet mirror 19 comprises a plurality of individual first facets 20, which are also referred to below as field facets. Of these facets, Fig. 1 only some examples are shown.

[0071] The first facets 20 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 20 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

[0072] As is known, for example, from DE 10 2008 009 600 A1, the first facets 20 themselves can also be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 19 can, in particular, be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0073] In the beam path of the illumination optics 4, a second facet mirror 21 is arranged downstream of the first facet mirror 19. If the second facet mirror 21 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 21 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first facet mirror 19 and the second facet mirror 21 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US Pat. No. 6,573,978.

[0074] The second facet mirror 21 comprises a plurality of second facets 22. In the case of a pupil facet mirror, the second facets 22 are also referred to as pupil facets.

[0075] The second facets 22 can also be macroscopic facets, which can, for example, be round, rectangular, or hexagonal, or alternatively facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0076] The second facets 22 may have planar or alternatively convex or concave curved reflection surfaces.

[0077] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (fly's eye integrator).

[0078] It may be advantageous to arrange the second facet mirror 21 not exactly in a plane that is optically conjugated to a pupil plane of the projection optics 10. In particular, the pupil facet mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0079] With the aid of the second facet mirror 21 and an imaging optical assembly in the form of a transmission optics 23, the individual first facets 20 are imaged into the object field 5.

[0080] The transmission optics 23 can comprise exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirrors, Normal Incidence Mirrors) and / or one or two mirrors for grazing incidence (GI mirrors, Grazing Incidence Mirrors). The illumination optics 4 has, in the embodiment shown in the Fig. 1, that is, after the collector 17 there are exactly three mirrors, namely the transmission optics 23, the first facet mirror 19 and the pupil facet mirror 21.

[0081] If the transmission optics 23 are omitted after the second facet mirror 21, the second facet mirror 21 is the last bundle-forming or actually the last mirror for the illumination radiation 16 in the beam path in front of the object field 5. An example of an illumination optics 4 without transmission optics is disclosed in Fig. 2 of WO 2019 / 096654 A1.

[0082] The imaging of the first facets 20 by means of the second facets 22 or with the second facets 22 and a transmission optics 23 into the object plane 6 is usually only an approximate imaging.

[0083] The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0084] In the Fig. In the example shown in Figure 1, the projection optics 10 comprises eight mirrors M1 to M8. Alternatives with four, six, ten, twelve or a different number of mirrors Mi are also possible. The projection optics 10 is an obscured optic. The last mirror M8 has a passage opening for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.3 and can be, for example, 0.33. The image-side numerical aperture can also be larger, can be greater than 35, can be greater than 0.4, can be greater than 0.45, can be greater than 0.5, can be greater than 0.55, can be greater than 0.6 and can be, for example, 0.7 or 0.75.

[0085] Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, 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.

[0086] Both the mirrors Mi and the mirrors of the transmission optics 23 and / or the collector 17 can be designed as mirror devices 24, which are described below with reference to the Fig. 2 to 4 will be explained in more detail.

[0087] The projection optics 10 can be designed in particular to be anamorphic. In particular, it has different image scales β x, β y in the x- and y-direction. The two magnifications β x , β y of the projection optics 10 are preferably (β x , β y ) = (+ / - 0.25, + / - 0.125). A positive magnification β means an image without image inversion. A negative sign for the magnification β means an image with image inversion.

[0088] The projection optics 10 results in a reduction in the ratio 4:1 in the x-direction, i.e. in the direction perpendicular to the scanning direction.

[0089] The projection optics 10 results in a reduction of 8:1 in the y-direction, i.e. in the scanning direction.

[0090] Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions, for example, with absolute values ​​of 0.125 or 0.25, are also possible.

[0091] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 5 and the image field 11 can be the same or can vary depending on the design of the projection optics 10. Examples of projection optics with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0092] Each of the pupil facets 22 is assigned to exactly one of the field facets 20 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the field facets 20. The field facets 20 generate a plurality of images of the intermediate focus on the pupil facets 22 assigned to them.

[0093] The field facets 20 are each imaged onto the reticle 7 by an associated pupil facet 22, superimposed on one another, to illuminate 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 achieved by superimposing different illumination channels.

[0094] By arranging the pupil facets, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the pupil facets that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting or illumination pupil fill fly.

[0095] A likewise preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

[0096] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below.

[0097] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0098] The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the pupil facet mirror 21. When the projection optics 10 images the center of the pupil facet mirror 21 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined spacing of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in spatial space. In particular, this surface exhibits a finite curvature.

[0099] It is possible that the projection optics 10 have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics 23, should be provided between the second facet mirror 21 and the reticle 7. With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0100] In the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 1, the pupil facet mirror 21 is not arranged in a surface conjugated to the entrance pupil of the projection optics 10. It is also tilted relative to the object plane 5. The second facet mirror 21 is further tilted relative to an arrangement plane defined by the first facet mirror 19.

[0101] Based on the Fig. 2 to 4, the mirror device 24 is explained in more detail below.

[0102] Fig. 2 shows a section of a mirror device 24. The mirror device 24 comprises a mirror 25 with a mirror base body 26. The mirror base body 26 has a reflection surface 27 and at least one side surface 28.

[0103] Adjoining the side surface 28 is a transition region 29 of the mirror 25, which, as will be explained below, serves to connect the mirror to a fastening component via the mirror base body 26. The transition region 29 has, in the Fig. 2 shown variant, exactly two receptacles 30.

[0104] Exactly one fastening component 31 is inserted into each of the receptacles 30. Depending on the design, several fastening components can also be provided per receptacle 30.

[0105] In the illustrated embodiment, the fastening components 31 are designed as cuboid-shaped metal blocks. The fastening components 31 have exactly two screw receptacles 31a.

[0106] The fastening components 31 are in the, in the Fig. 2, are inserted into the respective receptacles 30 of the transition area 29. In the illustrated embodiment, the receptacles 30 are designed as through holes, namely through bores. As a result of this, and due to a corresponding fit of the fastening components 31 relative to the receptacles 30, the fastening components 31 are held in the receptacles 30 in a form-fitting manner.

[0107] A connecting body 32 is attached to the transition area 29. In this embodiment, the connecting body 32 is secured by means of four fastening elements 33 designed as screws.

[0108] The fastening elements 33 connect the connecting body in a force-locking manner with the fastening components 31 arranged in the receptacles 30.

[0109] The fastening elements 33 penetrate the transition area 29 of the mirror and are screwed into the screw receptacles 31a of the fastening components 31.

[0110] Via the fastening elements 33, a fastening tensile force is generated between the connecting body 32 and the fastening components 31, which fastens the connecting body 32 in a force-fitting and form-fitting manner to the transition region 29 of the mirror 25.

[0111] The fastening components 31 are inserted into the receptacles 30, and after insertion, the connecting body 32 is frictionally connected to the mirror by means of the fastening elements 33. This clamps the mirror base body transition area 29 between the fastening components 31 and the connecting body 32. This clamping takes place between the contact surface of the fastening component 31 and the contact surface of the transition area 29 facing it in the direction of the connecting body 32. Only via this contact surface do the fastening components 31 actually rest on the transition area 29 due to the screw clamp.

[0112] The Fig. 2 a functional component 34 designed as a coolant line.

[0113] The coolant line 34 is connected to the at least one internal cooling channel via the connecting body 32. A liquid inflow channel 38 serves as a transition line section between the coolant line 34 and the at least one internal cooling channel.

[0114] The liquid inlet 38 is designed as a channel passing through the transition region 29.

[0115] The fluid inlet may have a larger cross-section than the at least one internal channel.

[0116] Fig. 3 shows the mirror base body 26 of the mirror device 24 in a sectional plan view. In the embodiment according to Fig. 2, the mirror base body 26 of the mirror 25 has exactly two transition regions 29, which are arranged on opposite side surfaces 28 of the mirror base body 26.

[0117] In this embodiment, each of the transition areas 29 has exactly two receptacles 30, which are designed as through openings.

[0118] The execution according to Fig. 3 has exactly one internal cooling channel, which is continuous. The cooling channel is connected to the Fig. 2 via the coolant inlet 38. On the opposite side surface 28, the cooling channel is connected by means of a coolant outlet 39 to a further, second functional component, which is also not shown in the Fig. 3. The cooling channel 35 between the coolant inlet 38 and the coolant outlet 39 is not shown in any detail.

[0119] The second functional component can be a coolant discharge line. The coolant discharge line can, in particular, be connected to the coolant inlet, thus forming a coolant circuit for cooling the mirror 25. It is also possible for the second functional component to be a coolant sink, which is designed to receive, store, and possibly transport and recycle used coolant.

[0120] Fig. 4 shows one of the transition areas 29 in an enlarged view. The transition area according to Fig. 4 has five through-openings 40, 41. Four of these openings 40 are identically formed. These identically formed through-openings 40 serve to guide the fastening elements 33 through the transition area 29 to the receptacles 30 of the fastening component 31.

[0121] The additional opening 41 serves for connection to the functional component 34. In this embodiment, there is precisely one such opening 41, to which either a coolant inlet 38 or a coolant outlet 39 can be connected. It is also possible for a transition region to have two such openings 41, for connecting a coolant outlet 39 and a coolant inlet 38 to the internal channel 35 of the mirror device 24. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 009 600 A1 [0072, 0075] US 2006 / 0132747 A1

[0073] EP 1 614 008 B1

[0073] US 6,573,978

[0073] DE 10 2017 220 586 A1

[0078] WO 2019 / 096654 A1

[0081] US 2018 / 0074303 A1

[0091]

Claims

[1] Mirror device (24), comprising - a mirror (25) with a mirror base body (26) -- with a reflection surface (27) and at least one side surface (28) and -- at least one mirror base body transition region (29) arranged on the side surface (28) of the mirror base body (26) -- at least one receptacle (30) arranged in the mirror base body transition area (29), - at least one fastening component (31) arranged in the at least one receptacle (30), - at least one connecting body (32) for fastening at least one functional component (34) to the mirror (25), wherein the connecting body (32) is attached to the at least one fastening component (31) by means of at least one fastening element (33), wherein the connecting body (32) is fastened to the mirror (25) by means of the fastening of the connecting body (32) to the fastening component (31). [2] Mirror device (24) according to claim 1, characterized by , that - the fastening component (31) has an internal thread and the fastening element (33) has a complementary external thread or - the fastening component (31) has an external thread and the fastening element (33) has a complementary internal thread. [3] Mirror device (24) according to one of the preceding claims, characterized by that the mirror base body (26) has at least one internal cooling channel. [4] Mirror device (24) according to claim 3, characterized by that the internal cooling channels have a constant cross-section. [5] Mirror device (24) according to one of the preceding claims, characterized by that the functional component (34) is a coolant line. [6] Mirror device (24) according to one of the preceding claims, characterized by that the mirror (25) is made, at least partially, of a brittle material. [7] Mirror device (24) according to one of the preceding claims, characterized by that a contact pressure of not more than 20 MPa is exerted on the mirror (25) via the connecting body (32) and the holder (30). [8] Optical system comprising - at least one mirror device according to one of claims 1 to 7. [9] Optical system according to claim 8, characterized by an illumination source (3) for generating illumination radiation (16). [10] Projection exposure apparatus (1) with an optical system according to claim 9.

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