WO2024061905A1

WO2024061905A1 - Optical assembly, optical system and projection exposure apparatus

Info

Publication number: WO2024061905A1
Application number: PCT/EP2023/075805
Authority: WO
Inventors: Robin Glorian
Original assignee: Carl Zeiss Smt Gmbh
Priority date: 2022-09-20
Filing date: 2023-09-19
Publication date: 2024-03-28
Also published as: DE102022209868A1

Abstract

The invention relates to an optical assembly (102) for a projection exposure apparatus (1), comprising an optical element (126) and a mount (128) carrying the optical element (126), wherein the mount (128) comprises a mount lower part (136) and a mount upper part (138) releasably connected to the mount lower part (136), wherein the optical element (126) is exclusively connected to the mount upper part (138), and wherein the mount upper part (138) comprises a plurality of spring-elastically deformable bearing feet (246) on which the optical element (126) bears.

Description

OPTICAL ASSEMBLY, OPTICAL SYSTEM AND PROJECTION EXPOSURE SYSTEM

The present invention relates to an optical assembly, an optical system with such an optical assembly and a projection exposure system with such an optical assembly and/or with such an optical system.

The content of the priority application DE 10 2022 209 868.4 is fully incorporated by reference.

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

Driven by the pursuit of ever smaller structures in the production of integrated circuits, EUV lithography systems, which use light with a wavelength in the range from 0.1 nm to 30 nm, in particular 13.5 nm, and DUV lithography systems, which use light with a wavelength in the range of 30 nm and 250 nm. Particularly in such EUV lithography systems, because of the high absorption of light of this wavelength by most materials, reflecting optics, i.e. mirrors, must be used instead of - as before - refracting optics, i.e. lenses.

It is desirable to be able to exchange such mirrors at the site of use of such a lithography system. Due to the limited space and the tolerances that must be maintained when replacing such a mirror, this requires a lot of time and effort and is therefore usually not possible at the site of use of the lithography system. This needs to be improved.

Against this background, it is an object of the present invention to provide an improved optical assembly. Accordingly, an optical assembly for a projection exposure system is proposed. The optical assembly comprises an optical element and a mount that carries the optical element, wherein the mount has a lower mount part and an upper mount part that is detachably connected to the lower mount part, wherein the optical element is connected exclusively to the upper mount part, and wherein the upper mount part has a plurality of spring-elastically deformable support feet on which the optical element rests.

Because the optical element is connected exclusively to the upper part of the frame, clamping forces for fixing the optical assembly are only introduced into the lower part of the frame and therefore not into the optical element. This makes it possible to easily replace the optical assembly at the location where the projection exposure system is used.

The optical assembly can be a mirror or a mirror module or can be referred to as such or as such. The optical element is a mirror. However, the optical element can also be a lens. The socket accommodates the optical element at least in sections. In the present case, the fact that the frame “carries” the optical element means in particular that the frame can absorb a weight of the optical element. For example, the optical element is glued to the frame.

The optical assembly is assigned a coordinate system with a first spatial direction or x-direction, a second spatial direction or y-direction and a third spatial direction or z-direction. The spatial directions are oriented perpendicular to each other. The optical element is assigned a central or symmetry axis, with respect to which the optical element and/or the mount can be constructed essentially rotationally symmetrical. However, this is not absolutely necessary. The axis of symmetry is parallel to or coincides with the z direction.

The frame is divided, in particular along the z-direction, into the lower frame part and the upper frame part. The lower part of the frame and the upper part of the frame are stacked or placed on top of one another when viewed along the z-direction. The upper part of the socket rests on the lower part of the socket. The upper part of the frame is firmly connected to the lower part of the frame. For this purpose, for example, a screw connection can be provided. The fact that the lower part of the frame is “detachably” connected to the upper part of the frame means in particular that the lower part of the frame and the frame The upper part of the solution can be connected and detached from each other as often as you like.

The fact that the optical element is connected “exclusively” to the upper part of the frame means in particular that no direct connection is provided between the optical element and the lower part of the frame. Forces applied to the lower part of the frame are therefore not introduced into the upper part of the frame or into the optical element. The upper part of the socket is arranged in particular between the optical element and the lower part of the socket. The lower part of the socket is ring-shaped. Therefore, the lower part of the frame can also be referred to as the lower frame ring. The upper part of the socket is also ring-shaped. Therefore, the upper part of the frame can be referred to as the upper frame ring.

According to one embodiment, the socket has a spacer ring arranged between the socket lower part and the socket upper part, wherein the spacer ring has contact areas that contact both the socket lower part and the socket upper part, and contact-free areas that contact neither the socket lower part nor the socket upper part.

The non-contact areas have a smaller or smaller wall thickness compared to the contact areas. In particular, the lower part of the socket and the upper part of the socket are firmly connected to one another, in particular screwed together, only in the area of the contact areas. In the contact-free areas, there is preferably no connection between the lower part of the socket and the upper part of the socket. The spacer ring enables adjustment in the z direction. The spacer ring can be finely ground to suit this purpose.

According to a further embodiment, the contact areas and the non-contact areas are arranged alternately.

This means in particular that a contact-free area is provided between two contact areas and a contact area is provided between two contact-free areas. Particularly preferably, exactly three contact areas are provided, which are arranged evenly distributed around the axis of symmetry. In particular, the contact areas are arranged offset from one another by 120°. The same applies to the contact-free areas. According to a further embodiment, the lower part of the socket and the upper part of the socket are connected to one another with the aid of connecting elements, the connecting elements being guided through the spacer ring through openings provided in the contact areas.

The connecting elements can be screws. Multiple connecting elements can be assigned to each contact area. For this purpose, the openings are provided on or in the contact areas. The connecting elements are thus guided from the upper part of the socket through the spacer ring into the lower part of the socket.

According to a further embodiment, the optical assembly further has a plurality of mount struts, which can be subjected to a clamping force in order to connect the optical assembly to a manipulator frame, the mount struts being mounted on the lower mount part.

In particular, the frame struts are screwed to the lower frame part. Preferably, exactly three frame struts are provided. The frame struts are evenly distributed around the axis of symmetry. In particular, the frame struts are placed offset by 120° from each other. Because the frame struts are mounted on the lower frame part, the respective clamping force is only introduced into the lower frame part and thus not into the upper frame part and the optical element.

According to a further embodiment, the socket has a plurality of weight force compensators arranged between the lower part of the socket and the upper part of the socket, which are designed to apply spring forces to the upper part of the socket, which are oriented in the opposite direction to a weight force of the optical element.

Preferably, the lower part of the socket and the upper part of the socket have recesses for receiving the weight compensators. This means in particular that the weight force compensators are arranged within the socket, in particular within the lower part of the socket and the upper part of the socket.

According to a further embodiment, each weight force compensator has a first guide element associated with the lower part of the socket, a second guide element associated with the upper part of the socket and a spring element, which is arranged between the first guide element and the second guide element.

The first guide element is placed within the lower part of the socket. The second guide element is placed within the upper part of the socket. The first guide element and the second guide element are preferably tubular. In particular, the first guide element and/or the second guide element are arranged at least in sections within the spring element. The spring element is a cylinder spring. In particular, the spring element is a compression spring. The spacer ring has openings through which the spring element is passed. This also means in particular that the weight force compensators are guided through the spacer ring.

According to a further embodiment, the first guide element is firmly connected to the lower part of the socket, with the second guide element being mounted in a linearly displaceable manner on the upper part of the socket.

For example, the first guide element is screwed to the lower part of the socket. The second guide element is preferably not firmly connected to the upper part of the socket, but is pressed against the upper part of the socket with the help of the spring element.

The upper part of the frame has several spring-elastically deformable support feet on which the optical element rests.

In the present case, a “spring-elastic deformation” is to be understood as meaning a reversible deformation. This means in particular that the contact feet can be moved from an undeformed to a deformed state by applying a force. As soon as this force is no longer effective, the support feet deform independently or automatically from the deformed state back to the undeformed state. In particular, the optical element is glued to the support feet. A UV-curable adhesive can be used for this.

According to a further embodiment, each support foot has a support section on which the optical element rests and a spring section which connects the support section to the upper part of the frame.

The spring section is in particular a leaf spring section and can therefore also be referred to as such. The optical element is connected to the support section glued. The support section is wedge-shaped and includes a support surface arranged obliquely to the axis of symmetry. The optical element rests on the support surface. In particular, the optical element is glued to the support surface. The optical element rests on the support surface of the support section with a contact surface arranged obliquely to the axis of symmetry.

According to a further embodiment, the support feet protrude from the upper part of the socket into the lower part of the socket.

In particular, the support feet protrude radially into the socket, in particular into the lower part of the socket. In particular, the spring section extends from the upper frame part along the axis of symmetry or along the z-direction into the lower frame part. The support foot is oriented in particular perpendicular to the spring section.

Furthermore, an optical system for a projection exposure system is proposed. The optical system includes an optical assembly as explained above and an actuable manipulator frame that supports the optical assembly.

The fact that the manipulator frame is “actuable” means in the present case that a position of the manipulator frame can be changed with the help of actuators attached to the manipulator frame. The optical assembly has six degrees of freedom, namely three translational degrees of freedom each along the x-direction, the y-direction and the z-direction and three rotational degrees of freedom each about the x-direction, the y-direction and the z-direction. This means that a position and an orientation of the optical assembly can be determined or described using the six degrees of freedom.

The “position” of the optical assembly means in particular its coordinates with respect to the x-direction, the y-direction and the z-direction. The “orientation” of the optical assembly is understood to mean, in particular, its tilting in relation to the three directions. This means that the optical assembly can be tilted about the x-direction, the y-direction and the z-direction. This results in six degrees of freedom for the position and orientation of the optical assembly. The “position” of the optical assembly is therefore to be understood as meaning both its position and its orientation. With the help of the actuators, the optical assembly can, for example, be moved from an actual position to a target position and vice versa. According to one embodiment, the optical system further has a locking frame connected to the manipulator frame, the optical assembly being arranged between the manipulator frame and the locking frame in order to apply a clamping force to the mount.

For example, the locking frame is firmly connected to the manipulator frame, for example screwed. The locking frame is designed to apply the clamping force along the axis of symmetry or the z-direction to the frame struts of the frame. The manipulator frame is actuable and can be moved, for example, along the z-direction in order to apply the clamping force to the frame struts or to free the frame struts from the clamping force.

According to a further embodiment, the optical system further has a plurality of bearing units, the optical assembly being mounted on the manipulator frame with the aid of the bearing units, each bearing unit having a spherical element and a groove element which at least partially accommodates the spherical element.

Preferably, exactly three storage units are provided, with each storage unit being able to be assigned two of the aforementioned degrees of freedom. With three storage units, there are six degrees of freedom. The storage units are preferably arranged evenly distributed around the axis of symmetry. In particular, the storage units are arranged offset from one another by 120°. The respective ball element can be connected to the manipulator frame, in particular screwed. The groove elements are firmly connected to the socket, in particular to the lower part of the socket. Each groove element has a V-shaped groove which accommodates the ball element at least in sections. Viewed along the z-direction, the bearing units and the mounting struts are arranged one below the other or one above the other.

Furthermore, a projection exposure system with such an optical assembly and/or with such an optical system is proposed.

The optical system is preferably a projection optics of the projection exposure system. However, the optical system can also be a lighting system. The projection exposure system can be an EUV lithography system. EUV stands for “Extreme Ultraviolet” and describes a wavelength of the beitslicht between 0.1 nm and 30 nm. The projection exposure system can also be a DUV lithography system. DUV stands for “Deep Ultraviolet” and describes a wavelength of work light between 30 nm and 250 nm.

In the present case, “on” is not necessarily to be understood as limiting it to exactly one element. Rather, several elements, such as two, three or more, can also be provided. Any other counting word used here should not be understood to mean that there is a limitation to exactly the number of elements mentioned. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

The embodiments and features described for the optical assembly apply accordingly to the proposed optical system and/or the proposed projection exposure system and vice versa.

Further possible implementations of the invention also include combinations of features or embodiments described above or below with regard to the exemplary embodiments that are not explicitly mentioned. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

Further advantageous refinements and aspects of the invention are the subject of the subclaims and the exemplary embodiments of the invention described below. The invention is further explained in more detail using preferred embodiments with reference to the accompanying figures.

Fig. 1 shows a schematic meridional section of a projection exposure system for EUV projection lithography!

FIG. 2 shows a schematic view of an embodiment of an optical system for the projection exposure system according to FIG. 1;

Fig. 3 shows a schematic top view of the optical system according to Fig. 2;

Fig. 4 shows a schematic side view of the optical system according to Fig. 2;

Fig. 5 shows the detailed view V according to Fig. 4; 6 shows a schematic sectional view of an embodiment of a weight compensator for the optical system according to FIG. 2;

Fig. 7 shows a schematic top view of an embodiment of a spacer ring for the optical system according to Fig. 2;

Fig. 8 shows a schematic side view of the spacer ring according to Fig. 7;

Fig. 9 shows a schematic sectional view of the optical system according to Fig. 2;

10 shows a schematic view of an embodiment of a mounting arrangement for mounting the optical system according to FIG. 2;

Fig. 11 shows a further schematic view of the mounting arrangement according to Fig. 10; and

Fig. 12 shows a schematic view of an embodiment of a tool for replacing an optical assembly of the optical system according to Fig. 2.

In the figures, identical or functionally identical elements have been given the same reference numerals, unless otherwise stated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

1 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of a lighting system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, lighting 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 module separate from the other lighting system 2. In this case, the lighting system 2 does not include the light source 3.

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 via a reticle displacement drive 9, in particular in a scanning direction.

A Cartesian coordinate system with an x-direction x, a y-direction y and a z-direction z is shown in FIG. 1 for explanation purposes. The x Direction x runs vertically into the drawing plane. The y-direction y is horizontal and the z-direction z is vertical. The scanning direction in FIG. 1 runs along the y-direction y. The z direction z runs perpendicular to the object plane 6.

The projection exposure system 1 includes projection optics 10. The projection optics 10 is used 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 ° is also between the object plane 6 and the Image level 12 possible.

A structure on the reticle 7 is imaged on a light-sensitive layer of a wafer 13 arranged in the area 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 along the y-direction y via a wafer displacement drive 15. The displacement on the one hand of the reticle 7 via the reticle displacement drive 9 and on the other hand of the wafer 13 via the wafer displacement drive 15 can be carried out synchronously with one another.

The light source 3 is an EUV radiation source. The light source 3 emits in particular EUV radiation 16, which is also referred to below as useful radiation, illumination radiation or illumination light. The useful radiation 16 in particular has a wavelength in the range between 5 nm and 30 nm. The light source 3 can be a plasma source, for example an LPP source (EnglJ Laser Produced Plasma), or plasma generated with the help of a laser a DPP source (EnglJ Gas Discharged Produced Plasma, plasma produced by gas discharge). It can also be a synchrotron-based radiation source. The light source 3 can be a free electron laser (EnglJ Free Electron Laser, FEL).

The illumination radiation 16, which emanates from the light source 3, is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and/or hyperboloid reflection surfaces. The at least one reflection surface of the collector 17 can be in grazing incidence (EnglJ Grazing Incidence, Gl), i.e. with angles of incidence greater than 45°, or in normal incidence (EnglJ Normal Incidence, NI), i.e. with angles of incidence smaller than 45°, with the illumination radiation 16 are applied. On the one hand, the collector 17 can be used to optimize its reflectivity be structured and/or coated for the useful radiation and on the other hand to suppress false light.

After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focus plane 18. The intermediate focus plane 18 can represent a separation between a radiation source module, having the light source 3 and the collector 17, and the illumination optics 4.

The lighting optics 4 comprises a deflection mirror 19 and, downstream of it in the beam path, a first facet mirror 20. The deflection mirror 19 can be a flat deflection mirror or alternatively a mirror with an effect that influences the bundle beyond the pure deflection effect. Alternatively or additionally, the deflection mirror 19 can be designed as a spectral filter which separates a useful wavelength of the illumination radiation 16 from false light of a wavelength that deviates from this. If the first facet mirror 20 is arranged in a plane of the illumination optics 4, which is optically conjugate to the object plane 6 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 20 includes a large number of individual first facets 21, which can also be referred to as field facets. Some of these first facets 21 are shown in FIG. 1 only as examples.

The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or part-circular edge contour. The first facets 21 can be designed as flat facets or alternatively as convex or concave curved facets.

As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also each be composed of a large number of individual mirrors, in particular a large number of micromirrors. The first facet mirror 20 can in particular be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 Al.

Between the collector 17 and the deflection mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction y.

A second facet mirror 22 is located downstream of the first facet mirror 20 in the beam path of the lighting optics 4. If the second facet mirror 22 is arranged in a pupil plane of the lighting optics 4, it will also known as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the lighting optics 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006/0132747 Al, EP 1 614 008 Bl and US 6,573,978.

The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

The second facets 23 can also be macroscopic facets, which can have, for example, round, rectangular or even hexagonal edges, or alternatively they can be facets composed of micromirrors. In this regard, reference is also made to DE 10 2008 009 600 Al.

The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

The lighting optics 4 thus forms a double faceted system. This basic principle is also known as the honeycomb condenser (EnglJ Fly's Eye Integrator).

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

With the help of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last beam-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path in front of the object field 5.

In a further embodiment of the illumination optics 4, not shown, transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which contributes in particular to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the lighting optics 4. are not. The transmission optics can in particular comprise one or two mirrors for perpendicular incidence (Ni mirror, normal incidence mirror) and/or one or two mirrors for grazing incidence (Gl mirror, grazing incidence mirror).

1, the lighting optics 4 has exactly three mirrors after the collector 17, namely the deflection mirror 19, the first facet mirror 20 and the second facet mirror 22.

In a further embodiment of the lighting optics 4, the deflection mirror 19 can also be omitted, so that the lighting optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

The imaging of the first facets 21 into the object plane 6 by means of the second facets 23 or with the second facets 23 and a transmission optics is generally only an approximate image.

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

In the example shown in FIG. 1, the projection optics 10 comprises six mirrors Ml to M6. Alternatives with four, eight, ten, twelve or another number of mirrors Mi are also possible. The projection optics 10 is a double obscured optics. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is larger than 0.5 and which can also be larger than 0.6 and, for example, 0.7 or can be 0.75.

Reflection surfaces of the mirrors Mi can be designed as free-form surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. The mirrors Mi, just like the mirrors of the lighting optics 4, can have highly reflective coatings for the lighting radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon. The projection optics 10 has a large object image offset in the y direction y between a y coordinate of a center of the object field 5 and a y coordinate of the center of the image field 11. This object image offset in the y direction y can be approximately like this be as large as a z-distance between the object plane 6 and the image plane 12.

The projection optics 10 can in particular be anamorphic. In particular, it has different imaging scales ßx, ßy in the x and y directions x, y. The two imaging scales ßx, ßy of the projection optics 10 are preferably (ßx, ßy) = (+/- 0.25, +/- 0.125). A positive magnification ß means an image without image reversal. A negative sign for the image scale ß means an image with image reversal.

The projection optics 10 thus leads to a reduction in size in the x direction x, that is to say in the direction perpendicular to the scanning direction, in a ratio of 44.

The projection optics 10 leads to a reduction of 84 in the y direction y, that is to say in the scanning direction.

Other image scales are also possible. Image scales of the same sign and absolutely the same in the x and y directions x, y, for example with absolute values of 0.125 or 0.25, are also possible.

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

One of the second facets 23 is assigned to exactly one of the first facets 21 to form an illumination channel for illuminating the object field 5. This can in particular result in lighting based on Köhler's principle. The far field is broken down into a large number of object fields 5 using the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to them.

The first facets 21 are each imaged onto the reticle 7 by an assigned second facet 23, superimposed on one another, in order to illuminate the object field 5. The illumination of the object field 5 is in particular as high as possible like. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by overlaying different lighting channels.

By arranging the second facets 23, 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 second facets 23 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 lighting setting or lighting pupil filling.

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 a redistribution of the illumination channels.

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

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

The entrance pupil of the projection optics 10 cannot regularly be illuminated precisely with the second facet mirror 22. When imaging the projection optics 10, which images the center of the second facet mirror 22 telecentrically onto the wafer 13, the aperture beams often do not intersect at a single point. However, an area can be found in which the pairwise distance of the aperture beams becomes minimal. This surface represents the entrance pupil or a surface conjugate to it in local space. In particular, this surface shows a finite curvature.

It may be that the projection optics have 10 different positions of the entrance pupil for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, 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 entrance pupil and the sagittal entrance pupil can be taken into account. In the arrangement of the components of the illumination optics 4 shown in FIG. 1, the second facet mirror 22 is arranged in a surface conjugate to the entrance pupil of the projection optics 10. The first facet mirror 20 is tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted to an arrangement plane that is defined by the deflection mirror 19. The first facet mirror 20 is arranged tilted to an arrangement plane which is defined by the second facet mirror 22.

2 shows a schematic view of an embodiment of an optical system 100 for the projection exposure system 1.

The optical system 100 can be part of a projection optics 10 as explained above. However, the optical system 100 can also be part of an illumination optics 4 as mentioned above. However, it is assumed below that the optical system 100 is part of such a projection optics 4. The optical system 100 is suitable for DUV lithography. However, the optical system 100 may also be suitable for EUV lithography.

The optical system 100 includes an optical assembly 102. The optical assembly 102 may be a mirror. The optical assembly 102 has an optically effective surface 104. The optically effective surface 104 is a mirror surface. The optically effective surface 104 is suitable for reflecting illumination radiation 16. The optically effective surface 104 can be oriented upwards or downwards in the orientation of FIG. 2.

In addition to the optical assembly 102, the optical system 100 includes a manipulator frame 106. The optical assembly 102 is coupled to the manipulator frame 106. The type of coupling between the optical assembly 102 and the manipulator frame 106 will be explained below. The manipulator frame 106 carries the optical assembly 102.

The optical assembly 102 or the optically effective surface 104 has six degrees of freedom, namely three translational degrees of freedom each along the first spatial direction or x-direction x, the second spatial direction or y-direction y and the third spatial direction or z-direction z as well as three rotational degrees of freedom each about the x-direction x, the y-direction y and the z-direction z. This means that a position and an orientation of the optical assembly 102 or the optically effective surface 104 can be determined or described using the six degrees of freedom. The “position” of the optical assembly 102 or the optically effective surface 104 is to be understood in particular as meaning its coordinates or the coordinates of a measuring point provided on the optical assembly 102 with respect to the x-direction x, the y-direction y and the z-direction z . The “orientation” of the optical assembly 102 or the optically effective surface 104 is to be understood in particular as its tilting with respect to the three directions x, y, z. This means that the optical assembly 102 or the optically effective surface 104 can be tilted about the x-direction x, the y-direction y and/or the z-direction z.

This results in the six degrees of freedom for the position and orientation of the optical assembly 102 or the optically effective surface 104. A "position" of the optical assembly 102 or the optically effective surface 104 includes both its position and its orientation. The term “location” can therefore be replaced by the phrase “position and orientation” and vice versa.

In Fig. 2, an actual position IL of the optical assembly 102 or the optically effective surface 104 is shown with solid lines and a desired position SL of the optical assembly 102 or the optically effective surface 104 is shown with dashed lines and the reference symbol 102' or 104'. An actual position IL of the manipulator frame 106 coupled to the optical assembly 102 is also shown with solid lines. A desired position SL of the manipulator frame 106 is shown with dashed lines and the reference symbol 106'.

The optical assembly 102 can be moved together with the manipulator frame 106 from the actual position IL to the target position SL and vice versa. For example, the optical assembly 102 or the optically effective surface 104 in the target position SL fulfills certain optical specifications or requirements that the optical assembly 102 or the optically effective surface 104 in the actual position IL does not fulfill.

In order to move the optical assembly 102 from the actual position IL to the target position SL, the optical system 100 includes an adjusting device 108. The adjusting device 108 is set up to adjust the optical assembly 102. In the present case, “adjustment” or “alignment” is to be understood in particular as changing the position of the optical assembly 102. When changing the position of the optical assembly 102, the manipulator frame 106 is moved along with the optical assembly 102. For example, the optical assembly 102 can be moved from the actual position IL to the target position SL and vice versa with the aid of the adjusting device 108. The adjustment or alignment of the optical assembly 102 can thus be carried out with the aid of the adjustment device 108 in all six of the aforementioned degrees of freedom. The adjustment device 108 is a so-called hexapod or can be referred to as such.

The adjusting device 108 includes several actuators 110, 112, 114, which are only shown very schematically in FIG. 2. The actuators 110, 112, 114 can also be referred to as actuators or actuating elements. The actuators 110, 112, 114 can be so-called bipods or can be referred to as such. Preferably, exactly three actuators 110, 112, 114 are provided, which are arranged offset from one another by 120°. The actuators 110, 112, 114 are preferably constructed identically.

The actuators 110, 112, 114 are connected to the manipulator frame 106 with the help of connection points 116, only one of which is provided with a reference number in FIG. For example, an adhesive connection or a screw connection can be provided at the connection points 116. Preferably exactly three connection points 116 are provided, with each connection point 116 being assigned an actuator 110, 112, 114.

Furthermore, each actuator 110, 112, 114 is coupled to a support structure 122 via two connection points 118, 120, only two of which are provided with a reference number in FIG. The support structure 122 may be a force frame or other immovable structure. The support structure 122 can also be referred to as a solid world.

With the help of the actuators 110, 112, 114, the manipulator frame 106 and the optical assembly 102 can be moved relative to the support structure 122. Each actuator 110, 112, 114 can be assigned two of the aforementioned degrees of freedom. With the three actuators 110, 112, 114, an adjustment of the optical assembly 102 in all six degrees of freedom is thus possible.

The actuators 110, 112, 114 can be controlled with the aid of a control and regulation unit 124 of the adjusting device 108 in order to adjust the optical assembly 102. All actuators 110, 112, 114 are operatively connected to the control and regulation unit 124, so that the control and regulation unit 124 controls the optical assembly 102 with the aid of a suitable control of the actuators 110, 112, 114. including the manipulator frame 106 can be adjusted in all six degrees of freedom. This can be done based on sensor signals from a sensor system, not shown, which can detect the actual position IL and the target position SL of the optical assembly 102.

Fig. 3 shows a schematic top view of the optical system 100. Fig. 4 shows a schematic side view of the optical system 100. Fig. 5 shows the detailed view V according to Fig. 4. Reference will be made to Figs. 3 to 5 at the same time.

The optical assembly 102 includes an optical element 126, in particular a mirror, and a mount 128 that carries the optical element 126. The optical element 126 has the previously mentioned optically effective surface 104. A central or symmetry axis 130 is assigned to the optical element 126. The optical element 126 can be constructed rotationally symmetrical to the axis of symmetry 130. However, this is not absolutely necessary.

A radial direction R is also assigned to the optical element 126. The radial direction R is perpendicular to the axis of symmetry 130 and oriented away from it. Furthermore, the optical element 126 has two semi-axes 132, 134, to which the optical element 126 can be constructed mirror-symmetrically.

The socket 128 can also be constructed rotationally symmetrical to the axis of symmetry 130. The socket 128 has a lower socket part 136 and an upper socket part 138 placed on the lower socket part 136. The lower socket part 136 and the upper socket part 138 are ring-shaped. Therefore, the lower socket part 136 can also be referred to as a lower socket ring and the upper socket part 138 can be referred to as an upper socket ring.

The optical element 126 is only connected, in particular glued, to the upper frame part 138. The lower socket part 136 and the upper socket part 138 are connected to one another using connecting elements 140, 142, 144. The connecting elements 140, 142, 144 can be screws. Preferably, at least exactly three connecting elements 140, 142, 144 are provided, which are arranged evenly distributed around the axis of symmetry 130. For example, the connecting elements 140, 142, 144 are arranged offset from one another by 120°.

The socket 128, in particular the socket lower part 136, is mounted on the manipulator frame 106 with the aid of bearing units 146, 148, 150. The La- Units 146, 148, 150 are constructed identically. Only the storage unit 148 will be discussed below. All statements regarding the storage unit 148 can be applied accordingly to the storage units 146, 150 and vice versa.

5 shows, the storage unit 148 is arranged between the lower socket part 136 and the manipulator frame 106. The socket 128 is supported on the manipulator frame 106 with the help of the storage unit 148. The bearing unit 148 has a ball element 152 with a ball flange 154 and a ball section 156 which the ball flange 154 carries. The bearing unit 148 is assigned a central or symmetry axis 158, to which the ball element 152 is constructed rotationally symmetrical.

The ball flange 154 is firmly connected to the manipulator frame 106. For example, the ball flange 154 is screwed to the manipulator frame 106. The ball section 156 can be made of a ceramic material, in particular Si3N4. The ball section 156 can be screwed to the ball flange 154.

In addition to the ball element 152, the bearing unit 148 includes a groove element 160. The groove element 160 is firmly connected to the lower socket part 136, for example screwed. The groove element 160 has a V-shaped groove 162 facing the spherical section 156 with two mutually inclined contact surfaces 164, 166. The ball section 156 contacts the contact surfaces 164, 166. The contact surfaces 164, 166 intersect in a common cutting line 168.

3 shows, the bearing units 146, 148, 150 are aligned in such a way that extensions 170, 172, 174 of the cutting lines 168 of all groove elements 160 of the bearing units 146, 148, 150 intersect in the axis of symmetry 130.

Now returning to FIG. 5, a spacer 176 is placed between the groove element 160 and the lower socket part 136. The spacer 176 may be a washer. Multiple spacers 176 may be provided. With the help of the spacer, the bearing unit 148 can be adjusted in the z-direction z.

3 and 4 show, the optical assembly 102 includes a plurality of mount struts 178, 180, 182. The mount struts 178, 180, 182 are identical built up. In particular, exactly three mounting struts 178, 180, 182 are provided, which are arranged evenly distributed around the axis of symmetry 130. In particular, the mounting struts 178, 180, 182 are arranged offset from one another by 120°. The frame struts 178, 180, 182 are only connected to the lower frame part 136, but not to the upper frame part 138.

Each mounting strut 178, 180, 182 is assigned exactly one storage unit 146, 148, 150. Viewed along the z-direction z, the respective storage unit 146, 148, 150 is placed below the mounting strut 178, 180, 182 assigned to it.

The optical system 100 further comprises a locking frame 184 which is connected to the manipulator frame 106. The locking frame 184 is only in the figure.

4 shown. With the help of the locking frame 184, a clamping force K can be applied to each mounting strut 178, 180, 182. For this purpose, the locking frame 184 can be movable along the z-direction z. The clamping forces K are introduced into the manipulator frame 106 via the mounting struts 178, 180, 182 and the bearing units 146, 148, 150.

The optical system 100 is also assigned several weight compensators 186, 188, 190, 192, 194, 196, the function of which will be explained later. The number of weight compensators 186, 188, 190, 192, 194, 196 is arbitrary. For example, exactly six weight force compensators 186, 188, 190, 192, 194, 196 are provided. The weight force compensators 186, 188, 190, 192, 194, 196 are placed between the mounting struts 178, 180, 182. The weight force compensators 186, 188, 190, 192, 194, 196 are arranged between the lower part of the socket 136 and the upper part of the socket 138.

6 shows a schematic sectional view of an embodiment of a weight force compensator 186 as mentioned above.

The weight force compensators 186, 188, 190, 192, 194, 196 are constructed identically. Only the weight force compensator 186 will be discussed below. All statements regarding the weight force compensator 186 can be applied accordingly to the weight force compensators 188, 190, 192, 194, 196 and vice versa.

The weight force compensator 186 is assigned a central or symmetry axis 198, to which the weight force compensator 186 is constructed rotationally symmetrical. Between the lower part of the socket 136 and the socket A spacer ring 200 is placed in the upper part 138. In the area of the weight force compensator 186, the spacer ring 200 contacts neither the lower frame part 136 nor the upper frame part 138. The spacer ring 200 has an opening 202. Such a breakthrough 202 is assigned to each weight force compensator 186, 188, 190, 192, 194, 196.

The lower socket part 136 has an opening 204 in which a lower or first guide element 206 is accommodated. The first guide element 206 comprises a mounting section 208, which is supported on the lower socket part 136, and a guide section 210 which extends into the opening 204. The mounting section 208 can be screwed to the lower socket part 136. The guide section 210 is tubular.

The upper part 138 has an opening 212 in which an upper or second guide element 214 is accommodated. The second guide element 214 includes a contact section 216, which is supported on a contact surface 218 of the opening 212. The second guide element 214 also has a guide section 220 which points in the direction of the first guide element 206. The guide section 220 is tubular. The second guide element 214 is not firmly connected to the upper part 138 of the socket.

A spring element 222 is mounted on the guide sections 210, 220. The spring element 222 is a compression spring. The spring element 222 can be a cylinder spring. The spring element 222 is supported on the mounting section 208 of the first guide element 206 and on the contact section 216 of the second guide element 214. The spring element 222 is guided through the opening 202 of the spacer ring 200.

The spring element 222 generates a spring force F oriented along the z direction z. The spring force F acts in the opposite direction to a weight force G of the optical element 126, which acts on the upper frame part 138. The spring force F and the weight force G act in opposite directions. The weight force G acts against the z-direction z, whereas the spring force F acts along the z-direction z.

Fig. 7 shows a schematic plan view of an embodiment of a spacer ring 200 as mentioned above. Fig. 8 shows a schematic side view of the spacer ring 200. In the following, reference is made to Figs. 7 and 8 simultaneously. The spacer ring 200 is constructed rotationally symmetrically to the axis of symmetry 130. The spacer ring 200 comprises a plurality of openings 202. Each opening 202 is assigned a weight force compensator 186, 188, 190, 192, 194, 196, the spring element 222 of which is guided through the respective opening 202.

The spacer ring 200 comprises a plurality of contact areas 224, 226, 228. Preferably, exactly three contact areas 224, 226, 228 are provided, which are arranged evenly distributed around the axis of symmetry 130. The contact areas 224, 226, 228 are arranged offset from one another by 120°. At the contact areas 224, 226, 228, the spacer ring 200 contacts both the lower socket part 136 and the upper socket part 138.

Each contact area 224, 226, 228 is assigned a bearing unit 146, 148, 150 and a mounting strut 178, 180, 182. The connecting elements 140, 142, 144 are guided through the contact areas 224, 226, 228. For this purpose, each contact area 224, 226, 228 has an opening 230, 232, 234. Each contact area 224, 226, 228 can have several openings 230, 232, 234. Accordingly, each contact area 224, 226, 228 can also be assigned several connecting elements 140, 142, 144.

Each contact area 224, 226, 228 has a lower contact section 236, which extends out of the spacer ring 200 on the underside, and an upper contact section 238, which extends out of the spacer ring 200 on the top side. The lower socket part 136 rests on the lower contact section 236. The upper socket part 138 rests on the upper contact section 238.

The spacer ring 200 further includes non-contact areas 240, 242, 244, at which the spacer ring 200 neither contacts the lower part of the socket 136 nor the upper part of the socket 138. This is achieved in that the contact-free areas 240, 242, 244 have a smaller wall thickness or wall thickness than the contact areas 224, 226, 228.

Three non-contact areas 240, 242, 244 are provided, which are arranged evenly distributed around the axis of symmetry 130. The contact areas 224, 226, 228 and the non-contact areas 240, 242, 244 are arranged alternately, so that a non-contact area 240, 242, 244 is arranged between two contact areas 224, 226, 228 and vice versa. The openings 202 are only provided in the non-contact areas 240, 242, 244. 9 shows a schematic sectional view of the optical system 100.

As previously mentioned, the optical element 126 is only connected to the upper frame part 138 and not to the lower frame part 136. To connect the optical element 126 to the upper frame part 138, this includes a large number of support feet 246, which are resiliently deformable. The optically effective surface 104 can be oriented upwards or downwards in the orientation of FIG. 9.

The support feet 246 extend from the upper part of the socket 138 against the radial direction R into the upper part of the socket 138. In particular, the support feet 246 extend into the lower part 136 of the socket. The support feet 246 are arranged evenly distributed around the axis of symmetry 130.

The support feet 246 and the upper part of the socket 138 are formed in one piece, in particular in one piece of material. "Integral" or "one-piece" means in particular that the upper part of the socket 138 and the support feet 246 are not made up of different sub-components, but form a common component. "Integral material", on the other hand, means that the support feet 246 and the upper part of the socket 138 are made entirely of the same material.

Only one support foot 246 will be discussed below. The support foot 246 has a wedge-shaped support section 248 with a support surface 250 on which the optical element 126 rests, as well as a spring section 252 which connects the support section 248 to the upper part 138 of the socket. The spring section 252 is resiliently deformable. The spring section 252 is a leaf spring and can therefore also be referred to as such. The support surface 250 is inclined obliquely to the axis of symmetry 130.

The optical element 126 has a circumferential contact surface 254 which rests on the support surface 250 of the support foot 246. For example, the contact surface 254 is glued to the support surface 250. The bond can be made, for example, using a UV-curable adhesive. The contact surface 254 is inclined relative to the axis of symmetry 130.

The optical element 126 also has a cylindrical radial scanning surface 256 which adjoins the contact surface 254. The radial scanning surface 256 is constructed rotationally symmetrical to the axis of symmetry 130. To the ra- Dial scanning surface 256 is followed by an axial scanning surface 258, which rotates in a ring around the axis of symmetry 130. The axial scanning surface 258 is oriented perpendicular to the axis of symmetry 130.

Now returning to FIG. 4, the optical system 100 further includes a housing 260 which houses the manipulator frame 106 and the optical assembly 102. The manipulator frame 106 can also be placed outside the housing 260. The housing 260 has an opening 262 that can be closed using a lid. The optical assembly 102 can be exchanged through the opening 262 (EnglJ Swap).

10 and 11 each show a schematic view of an embodiment of a mounting arrangement 264.

The assembly assembly 264 includes a measuring flange 266. The measuring flange can be part of a coordinate measuring machine. The lower socket part 136 is mounted on the measuring flange 266 with the aid of bearing units 146, 148, 150 as explained above. In other words, the mounting of the lower socket part 136 on the manipulator frame 106 is identical to the mounting of the lower socket part 136 on the measuring flange 266.

The mounting arrangement 264 is assigned a measuring head 268 for measuring the lower part 136 of the socket. The measuring head 268 can work in a contact and/or non-contact manner. The measuring head 268 can have different - including interchangeable - sensors. The measurement of the lower part of the socket 136 can be done tactilely. This means that the lower part of the socket 136 is scanned. The measuring head 268 can be part of the previously mentioned coordinate measuring machine. With the help of the measuring head 268, undesirable tilting of the lower part of the socket 136 can be determined. If the lower part of the socket 136 is tilted, it is aligned and measured again using the measuring head 268.

The spacer ring 200 (not shown) is then placed on the lower part of the socket 136 and the upper part of the socket 138 is placed on the lower part of the socket 136. The upper frame part 138 and the lower frame part 136 are pre-aligned with one another. For this purpose, azimuthal markings are attached to the lower part of the socket 136 and to the upper part of the socket 138, which are aligned with one another. The markings can be captured using a camera. The lower socket part 136 and the upper socket part 138 are not yet connected to one another using the connecting elements 140, 142, 144. 11 shows, the mounting arrangement 264 has a gripper flange 270 which is designed to grip the optical element 126. The gripper flange 270 includes a plurality of arms 272, 274, 276 on which the optical element 126 rests. With the help of the gripper flange 270, the optical element 126 is placed on the support feet 246 of the upper part 138, as indicated by an arrow 278. The optical element 126 is not yet bonded to the upper part of the frame 138. The lower socket part 136 and the upper socket part 138 are also not yet firmly connected to one another.

Cutouts can be provided on the optical element 126 so that the gripper flange 270 can grip the optical element 126. Azimuth markings can also be provided on the optical element 126, which are aligned with markings on the upper part of the frame 138. A camera can be provided to record the markings.

After placing the optical element 126 on the upper part of the frame 138, the optical element 126 is measured. The previously mentioned measuring head 268 can be used for this purpose. The optical element 126 is first measured on the radial scanning surface 256. For this purpose, a confocal sensor with a deflection mirror can be used. This can be part of the measuring head 268. The optical element 126 is then measured on the axial scanning surface 258. The axial scanning surface 258 is scanned for this purpose. This can be done using the measuring head 268.

To align the optical element 126, the lower frame part 136 is installed in a radially displaced manner relative to the upper frame part 138 with respect to the axis of symmetry 130. This results in a radial offset Ar between the lower frame part 136 and the upper frame part 138. This radial offset is preset by determining the so-called CAA vector. This can be determined using an assembly and/or calculation program. The upper part of the socket 138 is then tapped until the calculated radial offset Ar becomes zero. The lower socket part 136 is then screwed to the upper socket part 138.

The optical element 126 is then measured on the scanning surfaces 256, 258 as described above. A new radial offset Ar then results between the lower frame part 136 and the upper frame part 138. The radial offset Ar can be minimized by an iterative process. Residual errors can be minimized by aligning the optical element 126 in the upper part 138. For this purpose, the optical element 126 can be aligned on the support feet 246 by tapping and balling. The optical element 126 is then measured again on the scanning surfaces 256, 258. This is done with the help of the measuring head 268. If the residual error that is detected during the measurement is too large, the upper frame part 138 is realigned with the lower frame part 136 in an iterative process.

12 shows a schematic view of an embodiment of a tool 280 for replacing the optical assembly 102.

The tool 280 is designed to carry the optical assembly 102, which has the mount 128 and the optical element 126, and to insert it into the housing 260 through the opening 262 of the housing 260, as in FIG. 12 with the aid of an arrow 282 is indicated. The tool 280 includes a rail system with a fork to support and move the optical assembly 102.

A rail system is also provided on the manipulator frame 106. With the help of the tool 280, the optical assembly 102 is placed on the ball elements 152 of the bearing units 146, 148, 150. The optical assembly 102 is fed via the rail system of the manipulator frame 106. As soon as the optical assembly 102 rests on the bearing units 146, 148, 150, the mounting struts 178, 180, 182 are subjected to the clamping forces K with the aid of the locking frame 184. The manipulator frame 106 is then coupled to the actuators 110, 112, 114. Alternatively, the optical assembly 102 can also be coupled to the manipulator frame 106 using mandrels.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways. REFERENCE SYMBOL LIST

1 projection exposure system

2 lighting system

3 light source

4 Lighting optics

5 object field

6 object level

7 reticles

8 reticle holders

9 reticle displacement drive

10 projection optics

11 image field

12 image levels

13 wafers

14 wafer holders

15 W afer displacement drive

16 illumination radiation

17 collector

18 intermediate focus plane

19 deflection mirrors

20 first facet mirror

21 first facet

22 second facet mirror

23 second facet

100 optical system

102 optical assembly

102' optical assembly

104 visually effective area

104' visually effective area

106 Manipulator frame

106’ manipulator frame

108 adjustment device

110 actuator

112 actuator

114 actuator

116 connection point

118 connection point

120 connection point

122 supporting structure

124 control and regulation unit 126 optical element

128 version

130 axis of symmetry

132 semi-axis

134 semi-axis

136 socket base

138 socket top

140 fastener

142 connecting element

144 Connecting element

146 storage unit

148 storage unit

150 storage unit

152 spherical element

154 ball flange

156 spherical section

158 axis of symmetry

160 groove element

162 groove

164 contact area

166 contact area

168 cutting line

170 extension

172 extension

174 Extension

176 spacers

178 socket strut

180 socket strut

182 socket strut

184 barrier frames

186 weight compensator

188 weight compensator

190 weight compensator

192 weight compensator

194 weight compensator

196 weight compensator

198 axis of symmetry

200 spacer ring

202 breakthrough

204 breakthrough 206 leadership element

208 assembly section

210 leadership section section

212 Breakthrough

214 leadership element

216 investment section

218 contact surface

220 leadership section section

222 spring element

224 contact area

226 contact area

228 contact area

230 Breakthrough

232 breakthrough

234 breakthrough

236 Contact Section

238 Contact Section

240 area

242 area

244 area

246 support feet

248 edition section

250 bearing surface

252 spring section

254 contact area

256 scanning area

258 scanning area

260 cases

262 opening

264 Mounting arrangement

266 measuring flange

268 measuring head

270 gripper flange

272 Poor

274 Poor

276 Poor

278 Arrow

280 tools

282 Arrow F spring force

G weight force

K clamping force

Ml mirror M2 mirror

M3 mirror

M4 mirror

M5 mirror

M6 mirror x x direction y y direction z z direction

Ar offset

Claims

EXPECTATIONS

1. Optical assembly (102) for a projection exposure system (1), comprising an optical element (126), and a mount (128) which carries the optical element (126), the mount (128) having a base part (136) and has an upper frame part (138) detachably connected to the lower frame part (136), the optical element (126) being connected exclusively to the upper frame part (138), and wherein the upper frame part (138) has a plurality of resiliently deformable support feet (246) on which the optical element (126) rests.

2. Optical assembly according to claim 1, wherein the mount (128) has a spacer ring (200) arranged between the lower mount part (136) and the upper mount part (138), and wherein the spacer ring (200) has contact areas (224, 226, 228), which contact both the lower frame part (136) and the upper frame part (138), and non-contact areas (240, 242, 244) which neither contact the lower frame part (136) nor the upper frame part (138).

3. Optical assembly according to claim 2, wherein the contact areas (224, 226, 228) and the non-contact areas (240, 242, 244) are arranged alternately.

4. Optical assembly according to claim 2 or 3, wherein the lower frame part (136) and the upper frame part (138) are connected to one another with the aid of connecting elements (140, 142, 144), and wherein the connecting elements (140, 142, 144) through openings (230, 232, 234) provided in the contact areas (224, 226, 228) are guided through the spacer ring (200).

5. Optical assembly according to one of claims 1 - 4, further comprising a plurality of mounting struts (178, 180, 182) which can be acted upon by a clamping force (K) for connecting the optical assembly (100) to a manipulator frame (106), the Socket struts (178, 180, 182) are mounted on the socket base part (136).

6. Optical assembly according to one of claims 1 - 5, wherein the mount (128) has several between the lower mount part (136) and the upper mount part (138) arranged weight force compensators (186, 188, 190, 192, 194, 196), which are designed to apply spring forces (F) to the upper frame part (138) which are opposite to a weight force (G) of the optical element (126 ) are oriented.

7. Optical assembly according to claim 6, wherein each weight compensator (186, 188, 190, 192, 194, 196) has a first guide element (206) assigned to the lower part (136), a second guide element (214) assigned to the upper part (138) and a spring element (222) which is arranged between the first guide element (206) and the second guide element (214).

8. Optical assembly according to claim 7, wherein the first guide element (206) is firmly connected to the lower frame part (136), and wherein the second guide element (214) is mounted in a linearly displaceable manner on the upper frame part (138).

9. Optical assembly according to one of claims 1 - 8, wherein each support foot (246) has a support section (248) on which the optical element (126) rests, and a spring section (252) which connects the support section (248) to the upper part of the frame (138) connects.

10. Optical assembly according to one of claims 1 - 9, wherein the support feet (246) protrude from the upper frame part (138) into the lower frame part (136).

11. Optical system (100) for a projection exposure system (1), comprising an optical assembly (102) according to one of claims 1 - 10, and an actuable manipulator frame (106) which carries the optical assembly (102).

12. The optical system of claim 11, further comprising a locking frame (184) connected to the manipulator frame (106), the optical assembly (102) being arranged between the manipulator frame (106) and the locking frame (184) around the mount (128 ) to apply a clamping force (K).

13. Optical system according to claim 11 or 12, further comprising a plurality of storage units (146, 148, 150), wherein the optical assembly (102) with the help of Bearing units (146, 148, 150) are mounted on the manipulator frame (106), each bearing unit (146, 148, 150) having a ball element (152) and a groove element (160) which accommodates the ball element (152) at least in sections.

14. Projection exposure system (1) with an optical assembly (102) according to one of claims 1 - 10 and / or an optical system (100) according to one of claims 11 - 13.