Optical system and projection exposure system

Abstract

The invention relates to an optical system (100A, 100B) for a projection exposure system (1). The invention relates to an optical device (100) having an optical element (102, 102 ', 212), a support structure (134, 214) for supporting the optical element (102, 102', 212), and an interface (128A, 128B, 128C, 128D, 128E) for coupling the optical element (102, 102 ', 212) to the support structure (134, 214) wherein the interface (128A, 128B, 128C, 128D, 128E) has a first Hertz tooth (152) paired with the optical element (102, 102', 212) and a second Hertz tooth (166) paired with the support structure (134, 214), the first Hertz tooth (152) and the second Hertz tooth (166) engage with each other in a form-fitting manner in order to fix the position of the optical element (102, 102 ', 212) in the reference coordinate system (K).

Description

Technical Field

[0001] The invention relates to an optical system for a projection exposure apparatus and a projection exposure apparatus having such an optical system.

[0002] The content of the priority application DE 10 2023 201 858.6 is incorporated herein by reference in its entirety. Background Art

[0003] Microlithography is used to produce microstructured components, such as integrated circuits. Microlithographic processes are performed using a lithography apparatus comprising an illumination system and a projection system. An image of a mask (reticle) illuminated by the illumination system is projected by means of the projection system onto a substrate (e.g., a silicon wafer) coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system, in order to transfer the mask structure to the photosensitive coating of the substrate.

[0004] Driven by the desire for ever-smaller structures in integrated circuit production, EUV lithography equipment is currently being developed that uses light with a wavelength ranging from 0.1 nm to 30 nm (particularly 13.5 nm). In the case of such EUV lithography equipment, due to the high absorption of light of this wavelength by most materials, reflective optical elements (i.e., mirrors) must be used instead of the previous refractive optical elements (i.e., lens elements).

[0005] In such projection systems, it may be necessary to remove and reinstall mirrors or replace them with other mirrors. It should be possible to reproducibly re-establish the orientation of the respective mirrors during their installation. Therefore, it is desirable to provide an interface that allows the orientation of the mirrors to be re-established with high precision when the same mirrors are installed. Summary of the Invention

[0006] Against this background, the problem underlying the present invention is to provide an improved optical system for a projection exposure apparatus.

[0007] Therefore, an optical system for a projection exposure apparatus is proposed. The optical system comprises an optical element, a support structure for supporting the optical element, and an interface by means of which the optical element is coupled to the support structure, wherein the interface comprises a first Hertzsprung saw tooth assigned to the optical element and a second Hertzsprung saw tooth assigned to the support structure, and wherein the first Hertzsprung saw tooth and the second Hertzsprung saw tooth mesh to define a pose of the optical element in a reference coordinate system.

[0008] As a result of the interface comprising the first and second Hershel saw teeth, the optical element and the carrier structure can be reproducibly aligned with one another with little effort, so that the interface defines the pose of the optical element in the reference coordinate system.

[0009] The optical system is preferably a projection optical unit of a projection exposure apparatus or part of a projection optical unit. However, the optical system may also be an illumination optical unit of a projection exposure apparatus or part of an illumination optical unit. However, the following assumes that the optical system is a projection optical unit or part of such a projection optical unit. Therefore, the term "optical system" can be replaced by the term "projection optical unit."

[0010] In the present context, an "optical system" is understood to mean, in particular, a system that is suitable for processing or influencing light, in particular the illumination radiation in a projection exposure apparatus. In the present context, "processing" or "influencing" can be understood, for example, to mean deflecting and / or refracting light. For example, an optical element can reflect or deflect light.

[0011] The optical element is preferably a mirror or includes a mirror. In particular, the optical element can be an EUV mirror or include an EUV mirror. Preferably, the optical element includes a substrate, such as a glass ceramic block or a ceramic block, on which the optically active surface, in particular the mirror surface, is provided. However, the optical element can also be an optical waveguide or include an optical waveguide.

[0012] In the present case, the support structure can be, for example, a force frame for the optical system. However, the support structure can also be any other component, in particular, for example, the housing of an interferometer. In the present case, the support structure "supports" the optical element, meaning, in particular, that the support structure is designed to absorb the weight of the optical element. In particular, the support structure maintains the optical element in its position, in particular, in a target position for the optical element.

[0013] In the present case, "coupling" an optical element to a support structure by means of an interface means, in particular, that the interface connects the optical element to the support structure. For example, forces from the optical element are introduced into the support structure via the interface, or vice versa. However, this is not mandatory. Information about the pose that the optical element should adopt in the reference coordinate system can be stored in the interface. This information can be stored in the geometry of the interface, in particular in a sawtooth geometry. When the optical element is removed and subsequently installed or replaced, this information ensures that the optical element is returned to its predetermined pose without any additional adjustment or alignment.

[0014] In the present case, a "Herxburgh saw tooth" is understood to mean, in particular, an axially effective, flat-sided saw tooth. An interlocking connection is provided between the first and second Herxburgh saw teeth. The Herxburgh saw teeth thus interlock. The interlocking connection is produced by the two connecting partners (in the present case, the two Herxburgh saw teeth) meshing or engaging with one another. In the present case, "assigning" the first Herxburgh saw tooth to the optical element can mean, in particular, that the first Herxburgh saw tooth is attached to the optical element. However, this is not mandatory. The same applies to the second Herxburgh saw tooth and the support structure.

[0015] Both the first and second Hirshear saw teeth include a plurality of teeth that are distributed, preferably evenly spaced, around a central axis or axis of symmetry of the interface. The teeth of the Hirshear saw teeth extend radially outward from the axis of symmetry. The teeth of the first Hirshear saw tooth interlock with the teeth of the second Hirshear saw tooth, and vice versa.

[0016] In principle, Hexcel serrations enable the parallel connection of multiple pairs of surfaces in contact. This results in significant static overdetermination. When manufacturing Hexcel serrations, this high degree of static overdetermination requires extremely high surface accuracy and tolerances. However, once this is achieved, further improvements in overall accuracy can be achieved through so-called elastic averaging of inaccuracies. The principle of "elastic averaging" describes a situation in which two objects (in this case, Hexcel serrations) are connected to each other in a highly overdetermined manner via numerous contact points. In this case, the manufacturing accuracy of the machines used to manufacture the Hexcel serrations can be exceeded. The stiffness of the interface and its load-bearing capacity increase exponentially with increasing static overdetermination.

[0017] A reference coordinate system includes a first spatial direction, or x-direction, a second spatial direction, or y-direction, and a third spatial direction, or z-direction. In this reference coordinate system, the optical element has six degrees of freedom: three translational degrees of freedom in the x-, y-, and z-directions, and three rotational degrees of freedom about the x-, y-, and z-directions. In other words, the position and orientation of the optical element can be determined or described using these six degrees of freedom. The axis of symmetry corresponds to or extends parallel to the z-direction. For example, a first Hershel saw tooth and a second Hershel saw tooth mesh to define the pose of the optical element in all six degrees of freedom, or in only three.

[0018] The "position" of an optical element is understood to mean, in particular, its coordinates, or the coordinates of a point of interest located on the optical element, relative to the x-, y-, and z-directions. The "orientation" of an optical element is understood to mean, in particular, its tilt relative to the three directions. In other words, the optical element can be tilted relative to the x-, y-, and / or z-directions.

[0019] This provides six degrees of freedom in the position and / or orientation of the optical element. The "pose" of an optical element includes both its position and its orientation. Therefore, the term "pose" can be replaced by the phrase "position and orientation," and vice versa. In the present case, the first and second Hershel saws engage to "define" the pose of the optical element in the reference coordinate system. This should be understood as meaning that, in particular during removal and reinstallation of the optical element, or during replacement, the captured or calibrated pose of the optical element can be reproducibly and accurately reestablished with the aid of the two Hershel saws. For example, the optical element is brought into its target pose during reinstallation or replacement.

[0020] According to one embodiment, the optical system further comprises a first sawtooth portion attached to the optical element and comprising first Hershel saw teeth, and a second sawtooth portion attached to the carrier structure and comprising second Hershel saw teeth.

[0021] The first serration section can have a cylindrical geometry. For example, the first serration section can be configured rotationally symmetrically with respect to the axis of symmetry of the interface. For example, facing away from the first Hershel serration, the first serration section has an end face oriented perpendicular to the axis of symmetry. Furthermore, the first serration section includes an outer surface that extends rotationally symmetrically about the axis of symmetry. The same applies to the second serration section.

[0022] According to another embodiment, the first and / or second toothed portion comprises a fastening hole for fastening the first and / or second toothed portion and guided through the first and / or second Hirschsprung saw teeth.

[0023] The respective toothed sections can be interlockingly connected to another component or part by means of fastening holes, for example, by means of a threaded connection. For example, only the first toothed section may include such fastening holes. Additionally or alternatively, the second toothed section may also include such fastening holes. If the first toothed section includes fastening holes, these fastening holes are guided through the first Hirsch's saw tooth parallel to the axis of symmetry extending through the first Hirsch's saw tooth. Accordingly, if the second toothed section also includes fastening holes, these fastening holes are guided through the second Hirsch's saw tooth parallel to the axis of symmetry. In particular, the fastening holes are guided directly through the teeth of the respective toothed section.

[0024] According to another embodiment, the first saw tooth portion and / or the second saw tooth portion comprises a central hole, around which the first Hirsch saw tooth and / or the second Hirsch saw tooth extends.

[0025] For example, the respective Hershel saw tooth extends around the entire respective hole. However, this is not mandatory. The Hershel saw tooth can also extend only partially around the axis of symmetry. In this case, the respective Hershel saw tooth is segmented. The hole extends along the axis of symmetry. The hole can be constructed rotationally symmetrically with respect to the axis of symmetry. The centering element can be received in the hole. For example, both the first saw tooth part and the second saw tooth part include such a central hole. In this case, the first Hershel saw tooth extends around the hole in the first saw tooth part. In the case where the second saw tooth part also includes such a hole, the second Hershel saw tooth extends around the hole. In the present case, the respective Hershel saw tooth "extends around the hole" means, in particular, that the teeth of the respective Hershel saw tooth are arranged in a uniform distribution around the axis of symmetry of the interface. The Hershel saw tooth can extend around the respective hole in an annular or circular manner.

[0026] According to another embodiment, the first Hexcel saw tooth and / or the second Hexcel saw tooth is subdivided into saw tooth segments, which are arranged alternately with toothless segments of the first Hexcel saw tooth and / or the second Hexcel saw tooth.

[0027] In the present case, a "toothless" or "toothless" segment is understood to mean a segment of the corresponding saw tooth portion that is toothless. In particular, a toothless segment is always arranged between two saw tooth segments, and vice versa. For example, only the first Hirsch saw tooth or only the second Hirsch saw tooth can be subdivided into saw tooth segments. Furthermore, both the first and second Hirsch saw teeth can also be subdivided into saw tooth segments. Furthermore, it is also possible to subdivide only the second Hirsch saw tooth into saw tooth segments. The number of saw tooth segments and toothless segments depends on the requirements. However, preferably, at least two saw tooth segments and at least two toothless segments are provided. The need to provide toothless segments may be due to improved manufacturability of the corresponding Hirsch saw tooth.

[0028] According to another embodiment, the first saw tooth portion and / or the second saw tooth portion comprises a spring element which carries the teeth of the first Hirsch saw tooth and / or the second Hirsch saw tooth.

[0029] In this case, three degrees of freedom are decoupled and three degrees of freedom are blocked. Preferably, the spring element is a leaf spring element and can therefore also be referred to as such. Preferably, the teeth extend beyond the spring element. The teeth and the spring element can be formed as a single piece, in particular from one piece of material. In the present case, "single piece" or "integrally" means that the spring element and the teeth form a joint part and are not assembled from different component parts. In the present case, "formed from one piece of material" means that the spring element and the teeth are always made of the same material. For example, only the first sawtooth part includes such a spring element that carries the teeth of the first Hershel sawtooth. Alternatively or additionally, the second sawtooth part can also include such a spring element that carries the teeth of the second Hershel sawtooth.

[0030] According to a further embodiment, the spring element is oriented perpendicularly to the axis of symmetry of the interface.

[0031] In the present case, "perpendicular" is understood to mean an angle of 90°±10°, preferably 90°±5°, more preferably 90°±3°, more preferably 90°±1°, and more preferably exactly 90°. In particular, the spring element spans a plane arranged perpendicular to the axis of symmetry of the interface.

[0032] According to another embodiment, the spring element has its lowest stiffness when viewed along the axis of symmetry.

[0033] The tilted stiffness level about this axis of symmetry also has a low stiffness level. In particular, the spring element prevents the transmission of forces along the axis of symmetry via the interface. In this case, the transmission of forces along the axis of symmetry is preferably not achieved via the interface itself, but rather, for example, via a contact surface where the optical element indirectly or directly rests on the support structure. In this case, the corresponding Herschler teeth are positioned in the x- and y-directions and, with respect to the rotational freedom, in the z-direction. In very general terms, "stiffness" describes the body's resistance to elastic deformation imposed by external loads 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. For example, the stiffness of the spring element can be varied or adjusted by modifying its wall strength or thickness.

[0034] According to another embodiment, the optical system further comprises a mirror bushing assigned to the optical element and comprising a first serration portion, and a bushing block assigned to the carrier structure and comprising a second serration portion.

[0035] The support structure can be implemented as a hexapod. An interface is provided between the reflector bushing and the bushing block. For example, the first Hirshteeth can be directly attached to the reflector bushing. Thus, the second Hirshteeth can be formed directly on the bushing block. However, the first serration portion can also be a component separate from the reflector bushing and, for example, screwed to the reflector bushing. Thus, the second serration portion can also be a component separate from the bushing block and, for example, interlockingly connected, more specifically, screwed to the bushing block.

[0036] According to a further embodiment, the optical element comprises an optically active surface and a rear side facing away from the optically active surface, wherein the mirror bushing is connected to the rear side.

[0037] As mentioned above, the optically active surface can be a reflective mirror surface. For example, the optically active surface can be realized by a coating. Preferably, the back side has no defined optical properties.

[0038] According to a further embodiment, the mirror bushing and the first serration portion are formed in one piece, in particular from one piece of material, or in multiple pieces, and / or wherein the bushing block and the second serration portion are formed in one piece, in particular from one piece of material, or in multiple pieces.

[0039] For example, the first serration portion is formed directly on the reflector bushing. In this case, the reflector bushing and the first serration portion are formed as one piece. Alternatively, the reflector bushing and the first serration portion may also be two separate components that are detachably connected to each other. Correspondingly, the second Hershel serration may also be formed directly on the bushing block. In this case, the bushing block and the second serration portion are formed as one piece. Alternatively, the bushing block and the second serration portion may also be two separate components that are detachably connected to each other. It is also possible that the reflector bushing and the first serration portion are formed as one piece, and the bushing block and the second serration portion are formed as multiple pieces. The same applies in reverse.

[0040] According to another embodiment, the optical system further comprises three mirror bushings attached to the optical element, wherein each mirror bushing is assigned two degrees of freedom of the optical element.

[0041] Specifically, two degrees of freedom of the optical element are blocked at each mirror bushing. Thus, six degrees of freedom of the optical element are generated by three mirror bushings.

[0042] According to a further embodiment, the optical system further comprises three bipods, which couple the optical element to the carrier structure by means of bushing blocks, wherein each mirror bushing is assigned a bipod.

[0043] Three bipods or one hexapod are provided. In particular, a bushing block is also assigned to each bipod. This means, in particular, that three bushing blocks are provided, one for each mirror bushing. Each bipod is assigned two degrees of freedom of the optical element.

[0044] According to another embodiment, an optical component includes an optical waveguide and a fiber optic connector carrying the optical waveguide, wherein a first Hertzsprung serration is disposed on the fiber optic connector.

[0045] In this case, the carrier structure can be an interferometer, more particularly a housing of the interferometer.By means of the interface, the optical waveguide can be positioned with high precision on the carrier structure.

[0046] Furthermore, a projection exposure apparatus having such an optical system is proposed.

[0047] The optical system is preferably a projection optical unit of a projection exposure apparatus. However, the optical system may also be an illumination system. The projection exposure apparatus may be an EUV lithography apparatus. EUV stands for "extreme ultraviolet" and refers to wavelengths of working light between 0.1 nm and 30 nm. The projection exposure apparatus may also be a DUV lithography apparatus. DUV stands for "deep ultraviolet" and refers to wavelengths of working light between 30 nm and 250 nm.

[0048] In this context, "a" or "an" is not necessarily to be considered as limiting to exactly one element. On the contrary, a plurality of elements, for example two, three or more, may also be provided. Any other numerical value used herein should not be understood as limiting to the exact number of elements stated. On the contrary, upward and downward numerical deviations are possible unless otherwise indicated.

[0049] The embodiments and features described for the optical system apply correspondingly to the proposed projection exposure apparatus and vice versa.

[0050] Other possible implementations of the present invention also include combinations not explicitly mentioned of features or embodiments described above or below with respect to the exemplary embodiments. Those skilled in the art will also add individual aspects as improvements or supplements to the corresponding basic forms of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Further advantageous configurations and aspects of the invention are subject matter of the dependent claims and of exemplary embodiments of the invention described below.The invention is explained in more detail below based on preferred embodiments with reference to the drawings.

[0052] Figure 1 shows a schematic meridional cross section of a projection exposure apparatus for EUV projection lithography;

[0053] Figure 2 Display according to Figure 1 A schematic diagram of an embodiment of an optical system of a projection exposure apparatus;

[0054] Figure 3 Shown according to Figure 2 A schematic plan view of an optical system;

[0055] Figure 4 Shown for Figure 2 A schematic perspective view of an embodiment of an interface of an optical system;

[0056] Figure 5 shows another schematic perspective view of an interface;

[0057] Figure 6 Shown for Figure 2 A schematic cross-sectional view of another embodiment of an interface of an optical system;

[0058] Figure 7 Shown for Figure 2 A schematic cross-sectional view of another embodiment of an interface of an optical system;

[0059] Figure 8 Shown for Figure 2 A schematic plan view of another embodiment of an interface for an optical system;

[0060] Figure 9 Shown for Figure 2 a schematic side view of another embodiment of an interface for an optical system; and

[0061] Figure 10 Shown according to Figure 1 Schematic cross-sectional view of a further embodiment of an optical system of a projection exposure apparatus.

[0062] In the figures, identical or functionally identical elements have the same reference numerals unless otherwise indicated. In addition, it should be noted that the illustrations in the figures are not necessarily true to scale. DETAILED DESCRIPTION

[0063] Figure 1 An embodiment of a projection exposure apparatus 1 (lithography apparatus), in particular an EUV lithography apparatus, is shown. In addition to a light source or radiation source 3, the embodiment of an illumination system 2 of the projection exposure apparatus 1 comprises 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 include the light source 3.

[0064] 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 a reticle displacement drive 9, in particular in a scanning direction.

[0065] For the purpose of explanation, Figure 1 A Cartesian coordinate system is depicted with an x-direction x, a y-direction y, and a z-direction z. The x-direction x extends vertically into the plane of the drawing. The y-direction y extends horizontally, and the z-direction z extends vertically. The scanning direction is Figure 1 The z direction z extends perpendicular to the object plane 6.

[0066] The projection exposure apparatus 1 comprises a projection optical unit 10. The projection optical unit 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 extends parallel to the object plane 6. Alternatively, angles other than 0° are also possible between the object plane 6 and the image plane 12.

[0067] The structures on the reticle 7 are imaged onto the photosensitive layer of a wafer 13, which is 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 can be displaced, in particular in the y-direction y, by a wafer displacement drive 15. The displacement of the reticle 7 is achieved first by the reticle displacement drive 9, and secondly by the wafer displacement drive 15, so as to be synchronized with each other.

[0068] Light source 3 is an EUV radiation source. Light source 3 specifically emits EUV radiation 16, hereinafter also referred to as used radiation, illumination radiation, or illumination light. Used radiation 16 particularly has a wavelength in the range between 5 nm and 30 nm. Light source 3 can be a plasma source, such as an LPP (laser produced plasma) source or a GDPP (gas discharge produced plasma) source. It can also be a synchrotron-based radiation source. Light source 3 can be a free electron laser (FEL).

[0069] The illumination radiation 16 emitted by the light source 3 is focused by a light collector 17. The light collector 17 can be a light collector having one or more ellipsoidal and / or hyperbolic reflective surfaces. The illumination radiation 16 can be incident on at least one reflective surface of the light collector 17 at grazing incidence (GI) (i.e., at an angle of incidence greater than 45°) or at normal incidence (NI) (i.e., at an angle of incidence less than 45°). The light collector 17 can be structured and / or coated to optimize its reflectivity for the radiation being used and to suppress extraneous light.

[0070] Downstream of the light collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 may represent a separation between the radiation source module comprising the light source 3 and the light collector 17 and the illumination optics unit 4.

[0071] The illumination optical device unit 4 comprises a deflecting mirror 19 and a first facet mirror 20 arranged downstream of the deflecting mirror 19 in the beam path. The deflecting mirror 19 can be a plane deflecting mirror or, alternatively, a mirror with a beam-influencing effect that goes beyond a pure deflection effect. In an alternative or in addition thereto, the deflecting mirror 19 can be in the form of a spectral filter, which separates the used light wavelength of the illumination radiation 16 from extraneous light with a wavelength deviating therefrom. If the first facet mirror 20 is arranged in a plane of the illumination optical unit 4 which is optically conjugate to the object plane 6 and serves as a field plane, this facet mirror is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. In Figure 1 Only some of these first partial facets 21 are shown by way of example in FIG.

[0072] The first facets 21 can be implemented as macro facets, in particular rectangular facets or facets with an edge profile of an arc or a portion of a circle.The first facets 21 can take the form of planar facets or, as an alternative, convex or concave curved facets.

[0073] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also each be formed from a plurality of individual mirrors, in particular a plurality of micromirrors. In particular, the first facet mirrors 20 can be in the form of a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0074] The illuminating radiation 16 travels horizontally (ie in the y-direction y) between the light collector 17 and the deflecting mirror 19 .

[0075] In the beam path of the illumination optical unit 4, the second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in the pupil plane of the illumination optical unit 4, this facet mirror is also called a pupil facet mirror. The second facet mirror 22 can also be spaced apart from the 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 called a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1 and US 6,573,978.

[0076] 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 called pupil facets.

[0077] The second facets 23 can also be macroscopic facets, which can have, for example, circular, rectangular or hexagonal boundaries, or can alternatively be facets consisting of micromirrors. For details in this respect, reference is also made to DE 10 2008 009 600 A1.

[0078] The second facet 23 may have a planar or, alternatively, a convexly or concavely curved reflective surface.

[0079] The illumination optical unit 4 thus forms a two-facet system. This basic principle is also known as a fly's eye integrator.

[0080] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane optically conjugate to the pupil plane of the projection optical unit 10. In particular, the second facet mirror 22 can be arranged tilted relative to the pupil plane of the projection optical unit 10, as described, for example, in DE 10 2017 220 586 A1.

[0081] The second facet mirror 22 serves to image the individual first facets 21 into the object field 5 . The second facet mirror 22 is the last beam-shaping mirror or indeed the last mirror in the beam path upstream of the object field 5 for the illumination radiation 16 .

[0082] In another embodiment (not shown) of the illumination optical unit 4, a transfer optical unit, which particularly facilitates the imaging of the first facet 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 two or more mirrors, which are arranged one behind the other 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).

[0083] exist Figure 1 In the embodiment shown, the illumination optical unit 4 has exactly three mirrors downstream of the light collector 17 , specifically a deflection mirror 19 , a first facet mirror 20 and a second facet mirror 22 .

[0084] In another embodiment of the illumination optical unit 4 , the deflecting mirror 19 can also be omitted, and the illumination optical unit 4 can therefore then have exactly two mirrors downstream of the light collector 17 , specifically a first facet mirror 20 and a second facet mirror 22 .

[0085] The imaging of the first facet 21 into the object plane 6 by means of the second facet 23 or using the second facet 23 and the transfer optics is usually only an approximate imaging.

[0086] The projection optical unit 10 comprises a plurality of mirrors Mi, which are numbered consecutively according to their arrangement in the beam path of the projection exposure apparatus 1 .

[0087] exist Figure 1 In the example shown, the projection optical unit 10 comprises six mirrors M1 to M6. Alternative solutions with four, eight, ten, twelve, or a different number of mirrors Mi are also possible. The projection optical unit 10 is a doubly shaded 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 can be, for example, 0.7 or 0.75.

[0088] The reflective surface of the reflector Mi can be in the form of a free-form surface without an axis of rotational symmetry. Alternatively, the reflective surface of the reflector Mi can be designed as an aspherical surface with exactly one axis of rotational symmetry of the reflective surface shape. Like the reflectors of the illumination optical unit 4, the reflector Mi can have a highly reflective coating for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0089] The projection optical unit 10 has a large object-image offset in the y direction y between the y coordinate of the center of the object field 5 and the y coordinate of the center of the image field 11. This object-image shift in the y direction y can have approximately the same magnitude as the z distance between the object plane 6 and the image plane 12.

[0090] The projection optical unit 10 can particularly have a modified form. In particular, it can have different imaging ratios βx and βy in the x-direction x and the y-direction y. The two imaging ratios βx and βy of the projection optical unit 10 are preferably (βx, βy) = (+ / - 0.25, + / - 0.125). A positive imaging ratio β means imaging without image inversion. A negative imaging ratio β means imaging with image inversion.

[0091] The projection optical unit 10 thus results in a size reduction in the x-direction x, ie in a direction perpendicular to the scanning direction, with a ratio of 4:1.

[0092] The projection optical unit 10 results in a size reduction of 8:1 in the y-direction y, ie in the scanning direction.

[0093] Other imaging ratios are also possible. Imaging ratios with the same sign and the same absolute value in the x-direction x and the y-direction y are also possible, for example with an absolute value of 0.125 or 0.25.

[0094] The number of intermediate image planes in the x-direction x and the y-direction y in the beam path between the object field 5 and the image field 11 may be the same or different, depending on the embodiment of the projection optical unit 10. Examples of projection optical units with a different number of such intermediate images in the x-direction x and the y-direction y are known from US 2018 / 0074303 A1.

[0095] In each case, one of the second facets 23 is assigned to exactly one of the first facets 21 in order to form a corresponding illumination channel for illuminating the object field 5. This can, in particular, produce illumination according to the Köhler principle. The far field is decomposed into a plurality of object fields 5 by means of the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 respectively assigned to them.

[0096] The first facets 21 are each imaged onto the reticle 7 via the assigned second facets 23 and overlap with each other for the purpose of illuminating the object field 5. The illumination of the object field 5 is particularly uniform, preferably with a uniformity error of less than 2%. Field uniformity can be achieved by overlaying different illumination channels.

[0097] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by the 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 through which the light is guided, in particular a subset of the second facets 23. This intensity distribution is also referred to as illumination setting or illumination pupil filling.

[0098] A likewise preferred pupil homogeneity in the region of the part of the illumination pupil of the illumination optical unit 4 that is illuminated in a defined manner can be achieved by redistributing the illumination channels.

[0099] Further aspects and details of the illumination of the object field 5 , in particular of the entrance pupil of the projection optical unit 10 , are described below.

[0100] In particular, the projection optical unit 10 can have a concentric entrance pupil. The latter can be accessible. It can also be inaccessible.

[0101] The entrance pupil of the projection optical unit 10 cannot usually be precisely illuminated using the second facet mirror 22. In the case of imaging by the projection optical unit 10, which telecentrically images the center of the second facet mirror 22 onto the wafer 13, the aperture rays usually do not intersect at a single point. However, it is possible to find a region where the separation between pairs of aperture rays is minimized. This region represents the entrance pupil or a region conjugate thereto in real space. In particular, this region exhibits a finite curvature.

[0102] 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 part of the transfer optical unit, should be provided between the second facet mirror 22 and the reticle 7. With the help of this optical element, the different positions of the tangential and sagittal entrance pupils can be taken into account.

[0103] exist Figure 1 In the illustrated arrangement of the components of the illumination optical unit 4, the second facet mirror 22 is arranged in a region conjugate with the entrance pupil of the projection optical unit 10. The first facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to the arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged tilted relative to the arrangement plane defined by the second facet mirror 22.

[0104] Figure 2 A schematic diagram shows an embodiment of an optical system 100A for a projection exposure apparatus 1 . Figure 3 A schematic plan view of the optical system 100A is shown. Figure 2 and Figure 3 .

[0105] The optical system 100A can be the projection optical unit 4 described above, or a part of such a projection optical unit 4. Therefore, the optical system 100A can also be referred to as a projection optical unit. However, the optical system 100A can also be the illumination system 2 described above, or a part of such an illumination system 2. Therefore, the optical system 100A can also be referred to as an illumination system. However, it is assumed hereinafter that the optical system 100A is the projection optical unit 4, or a part of such a projection optical unit 4. The optical system 100A is suitable for EUV lithography. However, the optical system 100A can also be suitable for DUV lithography.

[0106] The optical system 100A may include a plurality of optical elements 102. Figure 2 and Figure 3 Only one of these is shown. Therefore, only one optical element 102 is discussed below. Optical element 102 may be one of the reflectors M1 to M6. Optical element 102 includes a substrate 104 and an optically active surface 106, such as a reflector surface. Substrate 104 may also be referred to as a reflector substrate. Substrate 104 may include glass, ceramic, glass-ceramic, or other suitable materials.

[0107] The optically active surface 106 is provided on the front side 108 of the substrate 104. The optically active surface 106 can be realized by means of a coating applied to the front side 108. The optically active surface 106 is a mirror surface. The optically active surface 106 is adapted to reflect the illumination radiation 16, in particular EUV radiation, during operation of the optical system 100A. Figure 3 In a plan view of , the optically active surface 106 may have an oval or elliptical geometry. The optical element 102 or the substrate 104 may have a triangular geometry. However, in general, any desired geometry may exist.

[0108] The optical element 102 has a rear side 110 facing away from the optically active surface 106 or the front side 108. The rear side 110 has no defined optical properties. In particular, the rear side 110 is not a mirror surface and therefore has no reflective properties.

[0109] A plurality of mirror bushings 112, 114, 116 are provided on the rear side 110. The mirror bushings 112, 114, 116 may be adhesive bushings. A first mirror bushing 112, a second mirror bushing 114, and a third mirror bushing 116 are provided. In other words, the optical element 102 includes exactly three mirror bushings 112, 114, 116. The mirror bushings 112, 114, 116 may have a geometrically identical design. The mirror bushings 112, 114, 116 are essentially cylindrical and have a convex shape on the underside. Figure 2 The mirror bushings 112, 114, 116 may be adhesively bonded to the substrate 104. The mirror bushings 112, 114, 116 form the corners of an imaginary triangle.

[0110] The optical element 102 or the optically active surface 106 has six degrees of freedom, namely, three translational degrees of freedom in a first spatial direction or x-direction x, a second spatial direction or y-direction y, and a third spatial direction or z-direction z, and three rotational degrees of freedom about the x-direction x, the y-direction y, and the z-direction z. In other words, the position and orientation of the optical element 102 or the optically active surface 106 can be determined or described using the six degrees of freedom.

[0111] The "position" of the optical element 102 or the optically active surface 106 is understood to be, in particular, its coordinates or the coordinates of a point of interest arranged on the optical element 102 with respect to the x-direction x, the y-direction y, and the z-direction z. The "orientation" of the optical element 102 or the optically active surface 106 is understood to be, in particular, its tilt with respect to the three directions x, y, and z. In other words, the optical element 102 or the optically active surface 106 can be tilted about the x-direction x, the y-direction y, and / or the z-direction z.

[0112] This results in six degrees of freedom in the position and / or orientation of the optical element 102 or the optically active surface 106. The "pose" of the optical element 102 or the optically active surface 106 encompasses both its position and its orientation. Therefore, the term "pose" can be replaced by the wording "position and orientation" and vice versa.

[0113] Figure 2 The actual posture IL of the optical element 102 or the optically effective surface 106 is shown using a solid line, and the target posture SL of the optical element 102 or the optically effective surface 106 is shown using a dashed line and reference numerals 102' and 106'. The optical element 102 can be brought from its actual posture IL to the target posture SL, and vice versa. For example, the optical element 102 in the target posture SL meets a specific optical specification or requirement that the optical element 102 in the actual posture IL does not meet.

[0114] To move the optical element 102 from the actual position IL to the target position SL, the optical system 100A includes an adjustment device 118. The adjustment device 118 is configured to adjust the optical element 102. In the present case, "adjustment" or "alignment" is understood to mean, in particular, a change in the position of the optical element 102. For example, the optical element 102 can be moved from the actual position IL to the target position SL, and vice versa, by means of the adjustment device 118. Adjustment or alignment of the optical element 102 can thus be implemented in all six aforementioned degrees of freedom by means of the adjustment device 118. The adjustment device 118 is known as a hexapod or can be referred to as a hexapod.

[0115] The adjustment device 118 includes a plurality of bipods 120, 122, 124. Figure 2 124 . Each mirror bushing 112 , 114 , 116 is assigned a bipod 120 , 122 , 124 . Specifically, this means that exactly three bipods 120 , 122 , 124 are provided. Each bipod 120 , 122 , 124 can be assigned two of the aforementioned degrees of freedom. Using three bipods 120 , 122 , 124 , adjustment of the optical element 102 in all six degrees of freedom is therefore possible. Bipods 120 , 122 , 124 are not necessarily suitable for adjusting the optical element 102. Furthermore, bipods 120 , 122 , 124 can also be suitable, for example, for maintaining the optical element 102 in its target position SL.

[0116] A first bipod 120 is assigned to the first reflector bushing 112. A second bipod 122 is assigned to the second reflector bushing 114. A third bipod 124 is assigned to the third reflector bushing 116. Bipods 120, 122, and 124 have the same design. Therefore, only first bipod 120 and first reflector bushing 112 will be discussed below, referred to as bipod 120 and mirror bushing 112, respectively. All explanations given below regarding bipod 120 also apply to bipods 122 and 124, and vice versa. Corresponding statements apply to mirror bushing 112 and mirror bushings 114 and 116.

[0117] Bipod 120 is coupled to mirror bushing 112 via bushing block 126. Bushing block 126 and mirror bushing 112 form an interface 128. Such an interface 128 is assigned to each bipod 120, 122, 124. In addition, bipod 120 is coupled to a supporting structure 134 via two joints 130, 132. Supporting structure 134 can be a force frame or any other immovable structure. Supporting structure 134 can also be referred to as a fixed structure.

[0118] Bipod 120 includes two manipulators 136 and 138, specifically a first manipulator 136 and a second manipulator 138. The six degrees of freedom of optical element 102 can be adjusted or blocked using all manipulators 136 and 138 from all bipods 120, 122, and 124. Manipulators 136 and 138 may also be referred to as actuating elements, actuating devices, or actuators. In particular, manipulators 136 and 138 are what are known as voice coil manipulators (VCMs) or voice coil actuators (VCAs), and may be referred to as such.

[0119] Two manipulators 136, 138 are coupled to the mirror bushing 112 by means of bushing blocks 126. Furthermore, the manipulators 136, 138 are coupled to the support structure 134 via coupling points 130, 132. The manipulators 136, 138 can be controlled by means of an open-loop and closed-loop control unit 140 of the adjustment device 118 in order to adjust the optical element 102.

[0120] All manipulators 136, 138 of all bipods 120, 122, 124 are operatively connected to the open-loop and closed-loop control unit 140, and as a result, the open-loop and closed-loop control unit 140 can adjust the optical element 102 in all six degrees of freedom by means of appropriate control of the manipulators 136, 138. This can be achieved based on sensor signals from a sensor system (not shown) that is capable of detecting the actual pose IL and the target pose SL of the optical element 102.

[0121] When optical element 102 is mounted, a measurement point (point of interest) on optical element 102 (particularly on optically active surface 106) can be calibrated relative to a reference (in the present case, a reference coordinate system K having the aforementioned directions x, y, and z). For example, a coordinate system K1 having an x-direction x1, a y-direction y1, and a z-direction z1 can be assigned to the point of interest. To calibrate optical element 102, coordinate system K1 is aligned with reference coordinate system K.

[0122] The calibrated optical element 102 can be removed and reinstalled or replaced with a different calibrated optical element 102. In the case of such aforementioned removal and installation or replacement of the optical element 102, the pose of the point of interest relative to the reference or the pose of the coordinate system K1 relative to the reference coordinate system K should not change. This requires a large and reproducible mounting accuracy.

[0123] Suitable cylindrical mating surfaces may be provided on the mirror bushing 112 and on the bushing block 126. These cylindrical mating surfaces are required to precisely thread the mirror bushing 112 and the bushing block 126 into one another. If the mirror bushing 112 and the bushing block 126 are not precisely aligned with one another, this may result in the mirror bushing 112 and the bushing block 126 becoming stuck and / or in excessive loads on the flexures provided on the manipulators 136, 138. Furthermore, the interface between the mirror bushing 112 and the bushing block 126 formed by the aforementioned mating surfaces is critical with respect to the mirror dynamics and deformation (surface shape deformation, SFD) of the optically active surface 106.

[0124] Remounting errors that may occur when mounting the optical element 102 are generally non-systematic errors. In the case of increasing the mass of the optical element 102 and / or increasing the volume of the optical element 102, the remounting errors may dominate the tolerance chain. In addition, the complexity of the remounting process also increases.

[0125] In this context, the interface 128 should be developed so that jamming between the bushing block 126 and the reflector bushing 112 is impossible. Furthermore, manual manipulation of the elements of the bipod 120 should not be necessary. Unacceptable effects, such as those related to dynamics, should no longer occur. Therefore, the interface 128 should resist jamming and be self-centering, highly accurate, and very rigid.

[0126] Figure 4 A schematic perspective view of an embodiment of an interface 128A as previously described is shown. Figure 5 Another schematic perspective view of the interface 128A is shown. Figure 4 and Figure 5 .

[0127] Interface 128A may be assigned a central axis or axis of symmetry 142, with respect to which interface 128A is configured in a rotationally symmetrical manner. Axis of symmetry 142 is oriented parallel to or coincides with the z-direction z. Interface 128A includes a first serration 144 assigned to mirror bushing 112. First serration 144 and mirror bushing 112 may be two separate components connected to one another. However, first serration 144 may also be formed integrally with mirror bushing 112, in particular, from one piece of material.

[0128] In this case, "one piece" or "integrally" means that the first serration 144 and the reflector bushing 112 form a joint component and are not assembled from different component parts. "Made from one piece of material" means that the serration 144 and the reflector bushing 112 are always made of the same material, such as a metal material.

[0129] The first serration 144 can be configured in a rotationally symmetrical manner with respect to the axis of symmetry 142. The first serration 144 is cylindrical and includes a cylindrical outer surface 146 and an end face 148 that can face the rear side 110. The end face 148 is oriented perpendicular to the axis of symmetry 142. In the center, the first serration 144 is perforated by a circular hole 150.

[0130] Away from the end face 148, the first saw tooth section 144 comprises a so-called first Hirshteeth saw tooth 152. In the present case, a "Hirshteeth saw tooth" is understood to be a saw tooth that is particularly effective in the axial direction and has a flat side. The first Hirshteeth saw tooth 152 comprises a plurality of teeth 154, 156, of which only two are located in the Figure 4 The teeth 154, 156 are arranged in a uniform distribution around the axis of symmetry 142 and extend radially outwards from the hole 150 to the outer surface 146. The first Hershel teeth 152 form a complete ring extending around the axis of symmetry 142. However, this is not mandatory.

[0131] In addition to first serration 144, interface 128A also includes a second serration 158. Second serration 158 and first serration 144 can be constructed in an identical, but mirror-inverted manner. Second serration 158 is associated with bushing block 126. Second serration 158 and bushing block 126 can be two separate components connected to one another. However, second serration 158 can also be formed integrally with bushing block 126, in particular, from one piece of material.

[0132] The second serration 158 can also be configured in a rotationally symmetrical manner with respect to the axis of symmetry 142. The second serration 158 is cylindrical and includes a cylindrical outer surface 160 and an end face 162 that can face away from the rear side 110. The end face 162 is oriented perpendicular to the axis of symmetry 142. In the center, the second serration 158 is perforated by a circular hole 164.

[0133] Away from the end face 162 and toward the first Hexcel serration 152, the second serration portion 158 includes a second Hexcel serration 166. The second Hexcel serration 166 includes a plurality of teeth 168, 170, only two of which are located at the ends of the second Hexcel serration. Figure 4 The teeth 168, 170 are arranged in a uniform distribution around the axis of symmetry 142 and extend radially outwards from the hole 164 to the outer surface 160. The second Hershel teeth 166 form a complete ring extending around the axis of symmetry 142. However, this is not mandatory.

[0134] To achieve maximum wear resistance, the Hertz teeth 152, 166 may be martensitic hardened and may have a surface coating such as a DLC (diamond-like carbon) coating, etc. This may reduce wear.

[0135] To connect the toothed sections 144, 158, their Hexcel serrations 152, 166 interlock with one another. The interlocking connection is created by the two connecting partners (in the present case, the Hexcel serrations 152, 166) meshing or engaging with one another. The interlocking connection can be released and re-established as often as necessary.

[0136] Due to the engagement of the Hexcel saw teeth 152, 166, the interface 128A can be Figure 4 The first state Z1 shown enters Figure 5 In the second state Z2 shown, the Hexcel saw teeth 152, 166 are not in interlocking engagement in the first state Z1. In the second state Z2, the Hexcel saw teeth 152, 166 are in interlocking engagement. To this end, the saw tooth sections 144, 158 are moved toward each other along the axis of symmetry 142, so that the Hexcel saw teeth 152, 166 engage with each other. In this case, the Hexcel saw teeth 152, 166 are "not engaged" in the first state Z1, meaning, in particular, that the Hexcel saw teeth 152, 166 are not in interlocking engagement with each other in the first state Z1.

[0137] As a result of using Hertz saw teeth 152, 166, the posture of optical element 102 can be positioned or fixed in all six degrees of freedom. A high reproducibility accuracy of preferably better than 5 μm can be achieved. This can be achieved despite a relatively large effective surface area due to the principle of elastic averaging. In addition, friction effects can also be reduced. There is no force-related stiffness. Since interface 128A is self-centering, a relatively low accuracy of interface 128A itself is required. Interface 128A allows the transmission of large forces and torques.

[0138] The aforementioned "elastic averaging" principle describes a situation in which two objects, in this case, the serrated portions 144 and 158, are connected to each other in a highly overdetermined manner through numerous contact points. A high degree of static overdetermination requires extremely precise surfaces and tolerances. However, once this is achieved, the overall accuracy is further improved due to the averaging of inaccuracies. In this case, the manufacturing accuracy of the machinery used in production can often be exceeded. Furthermore, as the degree of static overdetermination increases, the stiffness and load-bearing capacity increase exponentially.

[0139] The interface 128A allows for high-precision repeatability and reproducibility. This is virtually independent of the radius of the respective Hertz serrations 152, 166. This results in a high level of rigidity and a self-centering effect for the interface 128A. The interface 128A is insensitive to tilting of the serrations 144, 158 relative to one another.

[0140] To install the serrations 144, 158, all that is required is a movement in one direction, specifically along the axis of symmetry 142 or in the z-direction. This results in a capture range of approximately a few millimeters. The thermal center of the interface 128A is on the axis of symmetry 142. This results in high wear resistance due to the wide contact surface of the Hexcel serrations 152, 166.

[0141] Figure 6 A schematic cross-sectional view of another embodiment of the interface 128B described above is shown.

[0142] The explanations given below with respect to interface 128B apply accordingly to interface 128A. The reflector bushing 112 and bushing block 126 may be part of interface 128B. Figure 6 It is obvious that in this embodiment of the interface 128B, the first serration 144 is formed integrally with the reflector bushing 112, in particular formed from one piece of material. In other words, the reflector bushing 112 and the first serration 144 form a joint component.

[0143] In particular, the reflector bushing 112 includes a base 172, a first serrated portion 144, and a second serrated portion 144 extending from the base 172. Figure 6 The mirror bushing 112 may also be rotationally symmetrical with respect to the axis of symmetry 142. This is also not mandatory.

[0144] The second serrated portion 158 is formed as a single piece with the bushing block 126, in particular, is formed from one piece of material. That is, the bushing block 126 and the second serrated portion 158 form a joint component. In particular, the bushing block 126 includes a base 174, and the second serrated portion 158 is formed at Figure 6 The bore 164 may extend outwardly from the base 174 on the top side in an orientation of φ. The bore 164 may pass through the entire bushing block 126. However, this is not mandatory. The bushing block 126 may be rotationally symmetrical about the axis of symmetry 142. This is also not mandatory.

[0145] Figure 7 A schematic cross-sectional view of another embodiment of the interface 128C described above is shown.

[0146] The following explanation regarding interface 128C applies accordingly to interface 128A. In contrast to interface 128B, mirror bushing 112 and first serration 144 of interface 128C are two separate components that are connected (e.g., threaded) to each other. The same applies to bushing block 126 and second serration 158, which are also two separate components.

[0147] The reflector bushing 112 includes a base 172 having a contact surface 176 against which the end face 148 of the first serrated portion 144 rests and a cylindrical mating surface 178 against which the outer surface 146 of the first serrated portion 144 is guided. Accordingly, the bushing block 126 includes a base 174 having a contact surface 180 against which the end face 162 of the second serrated portion 158 rests and a cylindrical mating surface 182 against which the outer surface 160 of the second serrated portion 158 is guided.

[0148] The embodiments of the interfaces 128B and 128C can also be combined in such a way that, for example, the mirror bushing 112 and the first serration 144 are connected to each other in one piece, in particular in one piece of material, and the bushing block 126 and the second serration 158 are two separate components. The same applies vice versa.

[0149] Figure 8 A schematic plan view of another embodiment of the interface 128D described above is shown.

[0150] The following explanation of interface 128D applies accordingly to the various embodiments of interfaces 128A, 128B, and 128C described above. In particular, Figure 8 Only the second serration 158 of the interface 128D is shown. The following description of the second serration 158 applies correspondingly to the first serration 144.

[0151] The second sawtooth portion 158 includes the second Hexcel sawtooth 166 as described above, which has any desired number of teeth 168, 170. In contrast to the interface 128A, the second Hexcel sawtooth 166 of the interface 128D is not continuous but segmented. Therefore, the second Hexcel sawtooth 166 can be referred to as a segmented or non-continuous Hexcel sawtooth.

[0152] With respect to second Hirsch's saw tooth 166, "segmented" means, in particular, that a plurality of saw tooth segments 184, 186 having teeth 168, 170 are provided and arranged alternately with toothless segments or segments 188, 190 without teeth. Thus, a respective toothless segment 188, 190 is positioned between two saw tooth segments 184, 186, and vice versa. In contrast, "continuous" means that second Hirsch's saw tooth 166 extends completely around the axis of symmetry 142. Toothless segments 188, 190 may also be referred to as segments without teeth or segments not containing teeth.

[0153] There may be any desired number of sawtooth segments 184, 186. In particular, at least two sawtooth segments 184, 186 and at least two toothless segments 188, 190 are provided. Preferably, each sawtooth segment 184, 186 comprises at least four teeth 168, 170. The toothless segments 188, 190 may be provided for manufacturing reasons.

[0154] In the case where the second serration portion 158 and the bushing block 126 are two separate components, the second serration portion 158 may include a plurality of fastening holes 192, 194, 196, 198 through which fastening elements (e.g., screws) may be guided to securely connect the second serration portion 158 to the bushing block 126. Any desired number of fastening holes 192, 194, 196, 198 may be present. In particular, the fastening holes 192, 194, 196, 198 are arranged to be evenly spaced apart from one another around the axis of symmetry 142. The same applies to the first serration portion 144.

[0155] As mentioned above, such fastening holes 192, 194, 196, 198 may also be provided in the interfaces 128A, 128C. Figure 6 In the case of the interface 128B, the fastening holes 192 , 194 , 196 , 198 may be omitted because the first serration 144 is formed as one piece with the reflector bushing 112 and the second serration 158 is formed as one piece with the bushing block 126 .

[0156] Now return to Figure 8 , the fastening holes 192, 194, 196, 198 can be provided in both the saw tooth segments 184, 186 and the toothless segments 188, 190. In the region of the saw tooth segments 184, 186, the fastening holes 192, 194, 196, 198 are guided directly through the second Hershel saw tooth 166.

[0157] Figure 9 A schematic side view of another embodiment of an interface 128E as described above is shown.

[0158] The following explanation of interface 128E applies accordingly to the various embodiments of interfaces 128A, 128B, 128C, and 128D described above. In particular, Figure 9 Only the second serration 158 of the interface 128E is shown. The following description of the second serration 158 applies correspondingly to the first serration 144.

[0159] This embodiment of the interface 128E provides a segmented second Hershel sawtooth 166, as described with respect to FIG. Figure 8 For example, four sawtooth segments 200, 202, 204 are provided, between which the toothless segments 188, 190 ( Figure 8 ). Only the sawtooth segment 200 will be discussed below. All explanations regarding the sawtooth segment 200 are applicable to the sawtooth segments 202 and 204.

[0160] Sawtooth segment 200 preferably includes at least four teeth 168, 170 arranged on a spring element 206. Spring element 206 is a leaf spring element. Spring element 206 lies in a plane spanned by the x-direction x and the y-direction y. In other words, spring element 206 is oriented perpendicular to the z-direction z. Spring element 206 is coupled to second sawtooth portion 158 via two connecting elements 208, 210. Second Hershel sawtooth 166, spring element 206, and connecting elements 208, 210 are formed integrally with second sawtooth portion 158, in particular, from a single piece of material.

[0161] The spring element 206 is elastically deformable and ensures a very low stiffness of the interface 128E when considered in the z-direction z. The interface 128E blocks the degrees of freedom of translation in the x-direction x and the y-direction y, and blocks the degree of freedom of rotation about the z-direction z. Positioning in the z-direction z can be achieved by means of the mirror bushing 112 resting against the bushing block 126.

[0162] Figure 10 A schematic cross-sectional view of another embodiment of an optical system 100B is shown.

[0163] As described above, the embodiments of interfaces 128A, 128B, 128C, 128D, and 128E can be used in conjunction with both optical system 100A and optical system 100B. Optical system 100B includes optical element 212 and support structure 214. Optical element 212 includes first serration portion 144 having first Hirsch teeth 152, as described above. Support structure 214 includes second serration portion 158 having second Hirsch teeth 166. To align optical element 212 and support structure 214, Hirsch teeth 152 and 166 interlock with each other.

[0164] The optical element 212 includes an optical waveguide 216 and an optical fiber connector 218, which carries the optical waveguide 216. The first serration portion 144 is provided on the optical fiber connector 218. The optical fiber connector 218 and the first serration portion 144 can be connected to each other in one piece (particularly in one piece of material) or form two separate components.

[0165] The supporting structure 214 may be an interferometer, etc. The supporting structure 214 may be a housing, etc. The supporting structure 214 may include a base 220, on which the second serrated portion 158 is disposed. The base 220 and the second serrated portion 158 may be connected to each other in one piece, in particular, a single piece of material, or may form two separate components.

[0166] For example, due to damage to the optical waveguide 216, it may be necessary to replace the optical element 212 or the optical waveguide 216. Precise alignment of the optical waveguide 216 usually requires a considerable amount of time. With the aid of the embodiments of the interfaces 128A, 128B, 128C, 128D, 128E as explained above, it is possible to reproducibly align the optical element 212 or the optical waveguide 216 with a high degree of accuracy.

[0167] Although the present invention has been described based on exemplary embodiments, the present invention can be modified in various ways.

[0168] Reference Signs List

[0169] 1Projection exposure equipment

[0170] 2 Lighting system

[0171] 3 light sources

[0172] 4 Illumination optical unit

[0173] 5 physical field

[0174] 6 Object Plane

[0175] 7 Mask Master

[0176] 8-Reticle Holder

[0177] 9Mask displacement driver

[0178] 10 Projection optics unit

[0179] 11 Image Field

[0180] 12 Image plane

[0181] 13 chips

[0182] 14 Wafer Holder

[0183] 15 Chip displacement driver

[0184] 16 Illumination Radiation

[0185] 17 light collector

[0186] 18 Intermediate focal plane

[0187] 19 Deflecting mirror

[0188] 20 First facet mirror

[0189] 21 First facet

[0190] 22 Second facet reflector

[0191] 23 Second facet

[0192] 100A optical system

[0193] 100B optical system

[0194] 102 optical elements

[0195] 102' optical elements

[0196] 104 substrate

[0197] 106 optically effective surfaces

[0198] 106' optically effective surface

[0199] 108 front side

[0200] 110 rear side

[0201] 112 Mirror Bushing

[0202] 114 mirror bushing

[0203] 116 reflector bushing

[0204] 118 adjustment device

[0205] 120 bipod

[0206] 122 Bipod

[0207] 124 bipod

[0208] 126 bushing block

[0209] 128 interfaces

[0210] 128A interface

[0211] 128B interface

[0212] 128C interface

[0213] 128D interface

[0214] 128E interface

[0215] 130 junctions

[0216] 132 junctions

[0217] 134 load-bearing structure

[0218] 136 manipulator

[0219] 138 manipulator

[0220] 140 open-loop and closed-loop control units

[0221] 142 symmetry axis

[0222] 144 serrated part

[0223] 146 outer surface

[0224] 148 end face

[0225] 150 holes

[0226] 152 Hershey sawtooth

[0227] 154 teeth

[0228] 156 teeth

[0229] 158 serrated part

[0230] 160 outer surface

[0231] 162 end face

[0232] 164 holes

[0233] 166 Hershey Sawtooth

[0234] 168 teeth

[0235] 170 teeth

[0236] 172 base

[0237] 174 base

[0238] 176 contact surface

[0239] 178 mating surface

[0240] 180 contact surface

[0241] 182 mating surface

[0242] 184 serrated segment

[0243] 186 serrated segment

[0244] 188 paragraphs

[0245] 190 paragraphs

[0246] 192 fastening holes

[0247] 194 fastening holes

[0248] 196 fastening holes

[0249] 198 fastening holes

[0250] 200 serrated segments

[0251] 202 serrated segment

[0252] 204 serrated segment

[0253] 206 spring element

[0254] 208 connecting elements

[0255] 210 connecting element

[0256] 212 optical elements

[0257] 214 load-bearing structure

[0258] 216 optical waveguide

[0259] 218 fiber optic connector

[0260] 220 base

[0261] IL actual posture

[0262] K reference coordinate system

[0263] K1 coordinate system

[0264] M1 reflector

[0265] M2 reflector

[0266] M3 reflector

[0267] M4 reflector

[0268] M5 reflector

[0269] M6 reflector

[0270] SL target posture

[0271] xx direction

[0272] x1 x direction

[0273] yy direction

[0274] y1 y direction

[0275] zz direction

[0276] z1 z direction

[0277] Z1 state

[0278] Z2 state

Claims

1. An optical system (100A, 100B) for a projection exposure apparatus (1), comprising: Optical elements (102, 102', 212), a supporting structure (134, 214) for supporting the optical element (102, 102', 212), and an interface (128A, 128B, 128C, 128D, 128E) by means of which the optical element (102, 102', 212) is coupled to the carrier structure (134, 214), wherein the interface (128A, 128B, 128C, 128D, 128E) comprises a first Hertzsprung sawtooth (152) assigned to the optical element (102, 102', 212) and a second Hertzsprung sawtooth (166) assigned to the supporting structure (134, 214), and The first Hershel sawtooth (152) and the second Hershel sawtooth (166) are engaged to define a posture (SL) of the optical element (102, 102', 212) in a reference coordinate system (K).

2. The optical system of claim 1 , further comprising a first sawtooth portion (144) attached to the optical element (102, 102′, 212) and comprising the first Hershel sawtooth (152), and a second sawtooth portion (158) attached to the support structure (134, 214) and comprising the second Hershel sawtooth (166).

3. The optical system according to claim 2, wherein: The first saw tooth portion (144) and / or the second saw tooth portion (158) include fastening holes (192, 194, 196, 198) for fastening the first saw tooth portion (144) and / or the second saw tooth portion (158) and are guided through the first Hershel saw tooth (152) and / or through the second Hershel saw tooth (166).

4. The optical system according to claim 2 or 3, wherein: The first saw tooth portion (144) and / or the second saw tooth portion (158) includes a central hole (150, 164), and the first Hirsch saw tooth (152) and / or the second Hirsch saw tooth (166) extend around the central hole (150, 164).

5. The optical system according to any one of claims 2 to 4, wherein: The first Hirsch saw tooth (152) and / or the second Hirsch saw tooth (166) are subdivided into saw tooth segments (184, 186), and the saw tooth segments (184, 186) are arranged alternately with toothless segments (188, 190) of the first Hirsch saw tooth (152) and / or the second Hirsch saw tooth (166).

6. The optical system according to any one of claims 2 to 5, wherein: The first saw tooth portion (144) and / or the second saw tooth portion (158) includes a spring element (206) that supports the teeth (154, 156, 168, 170) of the first Hershel saw tooth (152) and / or the second Hershel saw tooth (166).

7. The optical system according to claim 6, wherein: The spring element (206) is oriented perpendicular to the axis of symmetry (142) of the interface (128E).

8. The optical system according to claim 7, wherein: The spring element (206) has its lowest stiffness when viewed along the axis of symmetry (142).

9. The optical system according to any one of claims 2 to 8, further comprising a mirror bushing (112, 114, 116) assigned to the optical element (102, 102') and comprising the first serration (144), and a bushing block (126) assigned to the carrier structure (134) and comprising the second serration (158).

10. The optical system according to claim 9, wherein: The optical element (102, 102') comprises an optically active surface (106, 106') and a rear side (110) facing away from the optically active surface (106, 106'), and wherein the mirror bushing (112, 114, 116) is connected to the rear side (110).

11. The optical system according to claim 9 or 10, wherein: The reflector bushing (112, 114, 116) and the first serration portion (144) are formed in one piece, in particular from one piece of material, or in multiple pieces, and / or wherein, The bushing block (126) and the second serration portion (158) are formed in one piece, in particular from one piece of material, or in multiple pieces.

12. The optical system according to any one of claims 9 to 11, further comprising three mirror bushings (112, 114, 116) attached to the optical element (102, 102'), wherein each mirror bushing (112, 114, 116) is allocated two degrees of freedom of the optical element (102, 102').

13. The optical system according to claim 12, further comprising three bipods (120, 122, 124) which couple the optical element (102, 102') to the carrier structure (134) by means of the bushing block (126), wherein each mirror bushing (112, 114, 116) is assigned a bipod (120, 122, 124).

14. The optical system according to any one of claims 1 to 8, wherein: The optical element (212) includes an optical waveguide (216) and an optical fiber connector (218) carrying the optical waveguide (216), wherein the first Hertzsprung serration (152) is arranged on the optical fiber connector (218).

15. A projection exposure apparatus (1) having an optical system (100A, 100B) according to any one of claims 1 to 14.

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