Optical system, projection exposure system, and method

Abstract

The invention relates to an optical system (100, 200A) for a projection exposure system (1), comprising a first component (202), a second component (204), and a transport securing means (214A) for applying a closing force (FV) to the first component (202) in order to secure the first component (202) to the second component (204) such that the first component (202) is secured from moving relative to the second component (204) while the optical system (100, 200A) is being transported, the transport securing means (214A) having a force transducer (226) for detecting the closing force (FV) so that the process of securing the first component (202) to the second component (204) is force-controlled.

Description

[0001] OPTICAL SYSTEM, PROJECTION LIGHTING SYSTEM AND

[0002] PROCEDURE

[0003] The present invention relates to an optical system for a projection exposure system, a projection exposure system with such an optical system and a method for transporting such an optical system.

[0004] The content of priority application DE 10 2024 206 014.3 is fully incorporated by reference.

[0005] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system, which includes an illumination system and a projection system. The image of a mask (reticule) illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system. This transfers the mask structure onto the photosensitive coating of the substrate.

[0006] Driven by the pursuit of ever smaller structures in the production of integrated circuits, EUV lithography systems are currently being developed that utilize light with wavelengths ranging from 0.1 nm to 30 nm, particularly 13.5 nm. Due to the high absorption of light of this wavelength by most materials, such EUV lithography systems require reflective optics, i.e., mirrors, instead of the previously used refracting optics, i.e., lenses. To prevent damage to the aforementioned optics or actuator units used to adjust them during transport of the projection system, transport safety devices are necessary.According to internal knowledge, these transport restraints press the components of the projection system to be secured into a defined state, preventing them from moving uncontrollably relative to each other in the event of vibrations. To avoid damaging the components, elastomers and spring elements can be used in the transport restraints. To achieve a controlled preload with this combination, such a transport restraint must exert a defined force on the components to be secured. According to internal knowledge, the necessary force can be adjusted by the distance the restraint travels.

[0007] Against this background, one object of the present invention is to provide an improved optical system.

[0008] Accordingly, an optical system for a projection exposure system is proposed. The optical system comprises a first component, a second component, and a transport lock for applying a locking force to the first component to fix the first component to the second component, so that the first component is secured against relative movement with respect to the second component during transport of the optical system, wherein the transport lock has a force sensor for detecting the locking force, so that the fixing of the first component to the second component is force-controlled.

[0009] Because the positioning of the first and second components is force-controlled rather than displacement-controlled, it is unnecessary to consider a tolerance chain of the optical system when the first component is solely force-controlled on the second component. Spacers are therefore unnecessary. The required locking force for securing the first component to the second component for transport can be directly controlled. This results in cost savings due to the elimination of spacers.

[0010] The optical system is preferably a projection optic of the projection exposure system or part of such a projection optic. However, the optical system can also be a lighting system of the projection exposure system or part of such a lighting system. Preferably, the first component is an optical element. However, the first component can be any component of the optical system. The second component can be a support structure that supports the first component. However, the second component can also be any component of the optical system.

[0011] The optical system can have any number of transport locks. The phrase "the first component is secured to the second component by means of the transport lock" means, in particular, that the first component cannot move relative to the second component. This is ensured by applying the locking force. The phrase "force-controlled" in the securing of the first component to the second component means, in particular, that the transport lock presses on the first component until the locking force is reached. Once the locking force is reached, the transport lock is preferably no longer moved. The locking force can then be observed during the transport of the optical system.

[0012] Preferably, the optical system can be moved from an operating state in which the first component is not fixed to the second component to a transport state in which the first component is fixed to the second component. To move the optical system from the operating state to the transport state, the transport lock is preferably moved linearly relative to the second component such that it moves towards the first component to apply the locking force. The force sensor can, for example, comprise a load cell, one or more strain gauges, or the like.

[0013] According to one embodiment, the first component is arranged at least partially within the second component.

[0014] In other words, the second component can enclose the first component. The second component can be multi-part. For example, the second component can have a first part and a second part that are detachably connected. In this case, the second part could be a transport cover that is mounted to the first part of the second component for transporting the optical system. Alternatively, the second component can also be a single-piece component, particularly one made of a single material. "Single-piece" or "one-part" primarily means that the second component is not composed of different sub-parts. In other words, in this case, the first part and the second part together form the second component as a single, continuous part.

[0015] According to another embodiment, the first component is an optical element, wherein the second component is a support structure that supports the first component.

[0016] In particular, the first component is a mirror, preferably a

[0017] EUV mirror. The first component can also be a lens. The first and second components can together form a mirror module of the optical system.

[0018] According to another embodiment, the transport lock is attached to the second component.

[0019] For example, the transport lock can be screwed into the second component. For this purpose, the second component can have a receiving section, such as a bore with an internal thread, into which the transport lock is screwed. The transport lock can, for example, have a base section that can be gripped with a tool. An engagement section of the transport lock is screwed into the receiving section of the second component, with the force sensor being positioned between the base section and the engagement section.

[0020] According to another embodiment, the locking force can be generated by making the transport lock movable relative to the second component.

[0021] In particular, the locking force is generated by the transport lock moving linearly relative to the second component. This linear movement of the transport lock relative to the second component can be achieved by screwing the transport lock into the second component. In this case, a rotational movement of the transport lock during screwing into the second component is converted into a linear movement of the transport lock towards the first component.

[0022] According to a further embodiment, the transport lock has a spring element for applying the locking force to the first component. The spring element can, for example, be an elastomer block. This prevents damage to the first component when the locking force is applied. Preferably, the spring element is attached to the front of the aforementioned engagement section of the transport lock.

[0023] According to another embodiment, the optical system has end-stop elements which limit the freedom of movement of the first component relative to the second component.

[0024] The end stop elements prevent the travel path of an actuator unit in the first component from being exceeded, thus reliably preventing damage to the actuator unit. Each end stop element can be rod-shaped and extend from the second component towards the first component. The first component has an opening or bore for each end stop element, in which the end stop element is received with clearance. In other words, the end stop elements do not touch the first component during operation. The end stop elements can be encased in an elastomer. Alternatively or additionally, the openings or bores provided in the first component can be lined with an elastomer. This elastomer can also be part of the end stop elements.

[0025] According to another embodiment, the end stop elements are at least partially spring-elastic deformable.

[0026] The spring-like deformability results firstly from the aforementioned elastomer of the end stop elements and secondly from the spring-like deformation of the rod-shaped end stop elements themselves. These can function as bending rods. According to another embodiment, the closing force acts on the end stop elements.

[0027] In particular, the closing force is exerted on the end stop elements during transport. In other words, the end stop elements absorb the closing force and transfer it to the second component.

[0028] According to another embodiment, the optical system has a signal processing unit for receiving and processing sensor signals from the force transducer.

[0029] The signal processing unit can be a computer or comprise a computer system. The signal processing unit can be coupled to an output unit. In the simplest case, the output unit could be, for example, a screen that displays when the locking force has been reached. Furthermore, the signal processing unit can be operatively connected to a power tool, such as a cordless screwdriver. In this case, the transport lock is screwed into the second component using the power tool. As soon as the locking force is reached, the signal processing unit switches off the tool, thus preventing the locking force from being exceeded.

[0030] According to another embodiment, the signal processing unit is designed to receive and evaluate sensor signals from the force transducer during the transport of the optical system.

[0031] This makes it possible, for example, to check whether the locking force was exceeded during transport. If so, it can be checked whether the first component is damaged. If the locking force was not exceeded during transport, it can be assumed that damage to the first component can be ruled out.

[0032] Furthermore, a projection exposure system with such an optical system is proposed.

[0033] The optical system is preferably a projection optic of the projection system. However, the optical system can also be an illumination system. The projection exposure system can be an EUV lithography system. EUV stands for "Extreme Ultraviolet" and refers to a wavelength of the working light between 0.1 nm and 30 nm. The projection exposure system can also be a DUV lithography system. DUV stands for "Deep Ultraviolet" and refers to a wavelength of the working light between 30 nm and 250 nm.

[0034] Furthermore, a method for transporting such an optical system for a projection exposure system is proposed. The method comprises the following steps: a) applying a shutter force to a first component of the optical system, such that the first component is fixed to a second component of the optical system; b) detecting the shutter force, such that the fixing of the first component to the second component is force-controlled; and c) transporting the optical system, wherein the first component is secured against relative movement with respect to the second component during transport by means of the shutter force.

[0035] Preferably, the optical system is moved from the operating state to the transport state during step a). In particular, steps a) and b) are performed simultaneously. In other words, the application and detection of the shutter force are carried out at the same time, so that the fixing of the first component to the second component is force-controlled.

[0036] According to one embodiment, step a) is performed manually or automatically based on sensor data concerning the closing force acquired during step b).

[0037] In a manual operation, the achievement of the required locking force is communicated to the user, for example, via an output unit as previously mentioned. Upon reaching the locking force, the user stops moving the transport lock towards the first component. In an automated operation, the signal processing unit can be coupled with an electric tool as previously mentioned. As soon as the required locking force is reached, the electric tool is automatically switched off.

[0038] According to another embodiment, step b) is performed during step c).

[0039] In other words, the shutter force is continuously monitored during transport of the optical system. This allows, for example, the determination of whether the shutter force was exceeded during transport. If the shutter force was exceeded, the first component can be inspected for damage. If the shutter force was not exceeded during transport, it can be assumed that the first component is undamaged.

[0040] The term "one" here should not necessarily be understood as restricting the number to exactly one element. Rather, it can also refer to multiple elements, such as two, three, or more. Similarly, every other counter used here should not be interpreted as restricting the number to the exact number stated. Instead, numerical deviations, both higher and lower, are possible unless otherwise specified.

[0041] The embodiments and features described for the optical system apply accordingly to the proposed projection exposure system and the proposed method, and vice versa.

[0042] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0043] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention will be explained in more detail below with reference to preferred embodiments and the accompanying figures.

[0044] Fig. 1 shows a schematic meridional section of a projection exposure system for EUV projection lithography!

[0045] Fig. 2 shows a schematic view of an embodiment of an optical system for the projection exposure system according to Fig. 1;

[0046] Fig. 3 shows a schematic view of another embodiment of an optical system for the projection exposure system according to Fig. 1; Fig. 4 shows another schematic view of the optical system according to Fig. 2;

[0047] Fig. 5 shows a force curve versus a distance traveled!

[0048] Fig. 6 shows a schematic view of another embodiment of an optical system for the projection exposure system according to Fig. 1;

[0049] Fig. 7 shows another schematic view of the optical system according to Fig. 6;

[0050] Fig. 8 shows a force curve versus a distance traveled! and

[0051] Fig. 9 shows a schematic block diagram of an embodiment of a method for transporting the optical system according to Fig. 2 or according to Fig. 3.

[0052] In the figures, identical or functionally equivalent elements have been labelled with the same reference symbols, unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0053] Fig. 1 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of the illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optic 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system 2. In this case, the illumination 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 moved, in particular in a scanning direction, via a reticle displacement drive 9.

[0054] Figure 1 illustrates a Cartesian coordinate system with an x-direction x, a y-direction y, and a z-direction z. The x-direction x extends perpendicularly into the plane of the drawing. The y-direction y is horizontal, and the z-direction z is vertical. In Figure 1, the scan direction runs along the y-direction y. The z-direction z is perpendicular to the object plane 6.

[0055] The projection exposure system 1 comprises a projection optic 10. The projection optic 10 serves to image the object field 5 onto an image field 11 in an image plane 12. The image plane 12 is parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0056] A structure on the reticulum 7 is imaged onto a photosensitive layer of a wafer 13 located in the image plane 12 within the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be moved, particularly along the y-direction y, via a wafer transfer drive 15. The movement of the reticulum 7 via the reticulum transfer drive 9 and of the wafer 13 via the wafer transfer drive 15 can be synchronized.

[0057] Light source 3 is an EUV radiation source. 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 has a wavelength in the range between 5 nm and 30 nm. Light source 3 can be a plasma source, for example, an LPP source (Laser Produced Plasma, plasma generated using a laser) or a DPP source (Gas Discharged Produced Plasma, plasma generated by gas discharge). It can also be a synchrotron-based radiation source. Light source 3 can be a free-electron laser (FEL).

[0058] The illumination radiation 16 emanating 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 reflective surfaces. The at least one reflective surface of the collector 17 can be illuminated by the illumination radiation 16 at grazing incidence (Gl), i.e., with angles of incidence greater than 45°, or at normal incidence (NI), i.e., with angles of incidence less than 45°. The collector 17 can be structured and / or coated to optimize its reflectivity for the useful radiation and to suppress stray light.

[0059] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optics 4.

[0060] The illumination optics 4 comprise a deflecting mirror 19 and, downstream in the beam path, a first faceted mirror 20. The deflecting mirror 19 can be a planar deflecting mirror or, alternatively, a mirror with an effect that influences the beam shape beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first faceted mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field faceted mirror. The first faceted mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. Only a few of these first facets 21 are shown in Fig. 1 as examples.

[0061] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or semicircular border contour. The first facets 21 can be designed as planar facets or alternatively as convexly or concavely curved facets.

[0062] As is known, for example, from DE 10 2008 009 600 Al, the first facets 21 can themselves each be composed of a plurality of individual mirrors, in particular a plurality 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.

[0063] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction y.

[0064] In the beam path of the illumination optics 4, a second faceted mirror 22 is arranged downstream of the first faceted mirror 20. If the second faceted mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil faceted mirror. The second faceted mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first faceted mirror 20 and the second faceted mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1 and EP 1614.

[0065] 008 Bl and the US 6,573,978.

[0066] 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.

[0067] The second facets 23 can also be macroscopic facets, which may, for example, have round, rectangular, or hexagonal edges, or alternatively, facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 Al in this regard.

[0068] The second facets 23 can have planar or alternatively convex or concave curved reflective surfaces.

[0069] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (EnglJ Fly's Eye Integrator).

[0070] It can be advantageous not to arrange the second faceted mirror 22 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the second faceted mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0071] With the aid of the second faceted mirror 22, the individual first facets 21 are imaged into the object field 5. The second faceted mirror 22 is the last beam-shaping, or indeed the last, mirror for the illumination radiation 16 in the beam path before the object field 5. In another embodiment of the illumination optics 4, not shown, a transmission optic can be arranged in the beam path between the second faceted mirror 22 and the object field 5, which contributes in particular to imaging the first facets 21 into the object field 5. The transmission optic can have exactly one mirror, or alternatively two or more mirrors, which are arranged one after the other in the beam path of the illumination optics 4. The transmission optic can, in particular, comprise one or two mirrors for perpendicular incidence (Ni mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (Gl mirrors, grazing incidence mirrors).

[0072] In the embodiment shown in Fig. 1, the lighting optics 4 has exactly three mirrors after the collector 17, namely the deflecting mirror 19, the first faceted mirror 20 and the second faceted mirror 22.

[0073] In a further embodiment of the lighting optics 4, the deflecting mirror 19 can also be omitted, so that the lighting optics 4 after the collector 17 can then have exactly two mirrors, namely the first faceted mirror 20 and the second faceted mirror 22.

[0074] The mapping of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optic into the object plane 6 is regularly only an approximate mapping.

[0075] The projection optics 10 comprise a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0076] In the example shown in Fig. 1, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The projection optics 10 is a double-obscured optic. The penultimate mirror M5 and the last mirror M6 each have an aperture for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0077] The reflective surfaces of the mirrors Mi can be designed as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflective surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflective surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0078] 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 as large as a z-distance between the object plane 6 and the image plane 12.

[0079] The projection optics 10 can be anamorphic. In particular, they have different image scales βx, βy in the x and y directions. The two image scales βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, + / - 0.125). A positive image scale β indicates an image without image inversion. A negative value for the image scale β indicates an image with image inversion. The projection optics 10 thus results in a reduction ratio of 4:1 in the x-direction x, that is, in the direction perpendicular to the scan direction.

[0080] The projection optics 10 lead to a reduction of 8D in the y-direction y, that is, in the scan direction.

[0081] Other magnification ratios are also possible. Magnification ratios with the same sign and absolute value in the x and y directions (x, y), for example with absolute values ​​of 0.125 or 0.25, are also possible.

[0082] 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, 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 A.

[0083] Each 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 result, in particular, in illumination according to Köhler's principle. The far field is divided into a multitude of object fields 5 with the help of the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to each of them.

[0084] The first facets 21 are each superimposed on a corresponding second facet 23 to illuminate the object field 5 onto the reticulum 7. The illumination of the object field 5 is particularly homogeneous. It preferably exhibits a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels. The illumination of the entrance pupil of the projection optics 10 can be geometrically defined by arranging the second facets 23. By selecting the illumination channels, especially the subset of the second facets 23 that carry light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting or illumination pupil filling.

[0085] Another 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.

[0086] 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.

[0087] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0088] The entrance pupil of the projection optics 10 cannot always be illuminated exactly by the second faceted mirror 22. When the projection optics 10 image the center of the second faceted mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found where the pairwise determined separation of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in real space. In particular, this surface exhibits a finite curvature.

[0089] The projection optics 10 may have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second faceted mirror 22 and the reticle 7. This optical element can accommodate the different positions of the tangential and sagittal entrance pupils.

[0090] In the arrangement of the components of the illumination optics 4 shown in Fig. 1, the second faceted mirror 22 is arranged in a plane conjugate to the entrance pupil of the projection optics 10. The first faceted mirror 20 is arranged tilted relative to the object plane 6. The first faceted mirror 20 is arranged tilted relative to an arrangement plane defined by the deflecting mirror 19. The first faceted mirror 20 is arranged tilted relative to an arrangement plane defined by the second faceted mirror 22.

[0091] Fig. 2 shows a schematic view of an embodiment of an optical system 100 for the projection exposure system 1.

[0092] The optical system 100 can be a projection optic 10 as mentioned above, or part of such a projection optic 10. Therefore, the optical system 100 can also be referred to as a projection optic. However, the optical system 100 can also be an illumination system 2 as explained above, or part of such an illumination system 2. Therefore, the optical system 100 can alternatively be referred to as an illumination system.

[0093] In the following, however, it is assumed that the optical system 100 is a projection optic 10 or part of such a projection optic 10. The optical system 100 is suitable for EUV lithography. However, the optical system 100 can also be suitable for DUV lithography. The optical system 100 can comprise several optical elements 102, of which only one is shown in Fig. 2. Therefore, only one optical element 102 will be discussed below. The optical element 102 can be one of the mirrors M1 to M6. Accordingly, the optical element 102 is a mirror, in particular an EUV mirror. However, the optical element 102 can also be a lens.

[0094] The optical system comprises, in addition to the optical element 102, a support frame 104 (Force Frame) and a sensor frame 106 (Sensor Frame). The support frame 104 is coupled to a fixed world 110 by means of a coupling element 108. The coupling element 108 may include springs. Several such coupling elements 108 may be provided. A "fixed world" is primarily understood to be a region of the optical system 100 that is immobile with respect to the support frame 104. For example, the fixed world 110 may be a base frame of the optical system 100.

[0095] The sensor frame 106 is coupled to the support frame 104 by means of a coupling element 112. The coupling element 112 may include springs. Several such coupling elements 112 may be provided. The support frame 104 thus supports the sensor frame 106. In other words, the sensor frame 106 is not directly coupled to the solid world 110, but indirectly or mediatedly via the support frame 104.

[0096] The optical element 102 can be adjusted or aligned in six degrees of freedom by means of an actuator unit 114. This allows the position of the optical element 102 to be changed. For example, the optical element 102 can be moved from an actual position in which it does not meet certain optical specifications to a desired target position in which it does meet the optical specifications. The sensor frame 106 serves as a reference for the position change of the optical element 102 as described above.

[0097] The optical element 102 is connected to the support frame 104 via the actuator unit 114. The optical element 102 can be connected to the actuator unit 114 by means of a coupling element 116, which in turn is connected to the support frame 104 via a coupling element 118. The coupling elements 116 and 118 can have springs. Any number of coupling elements 116 and 118 can be provided.

[0098] A control unit 120, for example, maintains a target position of the optical element 102 as previously mentioned. The control unit 120 can communicate with the actuator unit 114, which aligns or adjusts the optical element 102 based on control signals from the control unit 120. The control unit 120 interacts with the sensor frame 106 such that, for example, sensors attached to the sensor frame 106 measure the optical element 102. Based on sensor signals from these sensors, the control unit 120 then controls the actuator unit 114 to maintain the target position of the optical element 102.

[0099] To prevent components of the optical system 100, such as the optical element 102 and / or the actuator unit 114, from being damaged by vibrations during transport of the optical system 100, transport locks (TLs) can be used (not shown). These transport locks press the components to be secured into a defined state so that they cannot move uncorrelated due to vibrations. To prevent damage to the components, elastomers and spring elements can be used in the transport locks. To achieve controlled preload, such a transport lock must press on the components to be secured with a defined force.

[0100] Fig. 3 shows a schematic view of another embodiment of an optical system 200A. Fig. 4 shows another schematic view of the optical system 200A. Figs. 3 and 4 will be discussed simultaneously below.

[0101] The optical system 200A can be the optical system 100 shown in Fig. 2, where optical system 200A is depicted in a more schematic way compared to optical system 100. Optical system 200A comprises a first component 202. The first component 202 can be the previously mentioned optical element 102. Alternatively, the first component 202 can also be, for example, a sensor frame 106 as previously mentioned. In principle, the first component 202 can be any component of optical system 200A.

[0102] In addition to the first component 202, the optical system 200A comprises a second component 204. The second component 204 can be a supporting structure that carries the first component 202. For example, the first component 202 and the second component 204 together can form a mirror module of the optical system 200A. In principle, the second component 204 can be any component of the optical system 200A. The second component 204 can enclose the first component 202. In other words, the first component 202 can be located inside the second component 204. However, this is not mandatory.

[0103] The second component 204 can be multi-part and comprise a first component 206 and a second component 208. The components 206 and 208 can be permanently joined together. In particular, the components 206 and 208 can be joined together in one piece, especially in one piece of material. "One piece" or "one-part" in this context means that the components 206 and 208 are not separable from one another, but rather that the components 206 and 208 together form the second component 204 as a single component. "One-piece" in this context means that the second component 204 is manufactured entirely from the same material. Alternatively, the first component 206 and the second component 208 can also be designed to be separable from one another. For example, the components 206 and 208 are screwed together. In this case, the second component 208 can, for example, be a so-called transport cover.

[0104] Several end-stop elements 210, 212 are arranged between the first component 202 and the second component 204. The number of end-stop elements 210, 212 is arbitrary. In this case, the end-stop elements 210, 212 are arranged between the first component 206 of the second component 204 and the first component 202. The end-stop elements 210, 212 are rigidly connected to the second component 204, in particular to the first component 206. The end-stop elements 210, 212 limit the range of motion of the first component 202 relative to the second component 204 such that the aforementioned actuator unit 114 cannot move into a position in which it would be damaged. In an operating state Z 1 of the optical system 200A shown in Fig. 3, the end stop elements 210, 212 do not contact the first component 202.

[0105] The end stop elements 210, 212 can be rod-shaped, in particular flexible rod-shaped, and extend out of the second component 204, in particular from the first component 206, and extend into openings or bores provided in or on the first component 202. In the operating state ZI, however, the end stop elements 210, 212 do not contact the walls of these openings or bores provided in the first component 202.

[0106] The end stop elements 210, 212 can be spring-elastic deformable, at least in sections. For example, the end stop elements 210, 212 are bending bars. Furthermore, the end stop elements 210, 212 can be encased, for example, with an elastomer that also allows spring-elastic deformation. Alternatively, the openings or bores provided in the first component 202 can be lined with an elastomer that also allows spring-elastic deformation. This elastomer provided in the openings or bores is also part of the end stop elements 210, 212. The spring-elastic deformability of the end stop elements 210, 212 is illustrated in Figures 3 and 4 by depicting the end stop elements 210, 212 as springs.

[0107] The optical system 200A further includes a transport lock 214A. The transport lock 214A allows the first component 202 to be fixed to the second component 204 in such a way that the first component 202 cannot move relative to the second component 204 during transport of the optical system 200A. The transport lock 214A allows the optical system 200A to be moved from the operating state ZI shown in Fig. 3 to a transport state Z2 shown in Fig. 4 and vice versa. The optical system 200A can have any number of transport locks 214A.

[0108] The transport lock 214A is attached to the second component 204, in particular to the second part 208. The second component 204, in particular the second part 208, can have a receiving section 216, in particular in the form of a threaded bore, into which the transport lock 214A is screwed. The transport lock 214A comprises a base section 218. The base section 218 can, for example, have an external hexagon. The base section 218 can, for example, be gripped with a tool to screw the transport lock 214A into the receiving section 216.

[0109] Furthermore, the transport lock 214A comprises an engagement section 220, which may have an external thread that engages with an internal thread of the receiving section 216. A mechanical end stop 222 is attached to the engagement section 220, which can come into contact with the second component 208 when the transport lock 214A is screwed into the receiving section 216. The mechanical end stop 222 thus limits the maximum distance by which the transport lock 214A can be moved relative to the second component 204, in particular to the second component 208.

[0110] A spring element 224 is attached to the front of the handle cut-off section, pointing towards the first component 202. In operating state ZI, the spring element 224 does not contact the first component 202. In transport state Z2, the spring element 224 rests against the first component 202. The spring element 224 can be an elastomer block.

[0111] A force sensor 226 of the transport securing device 214A is arranged between the spring element 224 and the handle section 220. The force sensor 226 can be a load cell, a strain gauge, or the like. Depending on the design, the sensor type for the force sensor 226 is freely selectable. The operating principle of the force sensor 226 is also freely selectable. For example, the operating principle can be analog, digital, or mechanical. The force sensor 226 can be freely positioned within the transport securing device 214A. A signal processing unit 228 is associated with the force sensor 226, which is suitable for receiving and processing sensor signals from the force sensor 226. The force sensor 226 is operatively connected to the signal processing unit 228 by means of a data connection 230. The data connection 230 can be wired or wireless. A cable gland must be provided for the 230 data connection.The force transducer 226 has a suitable connection for signal evaluation.

[0112] The signal processing unit 228 can be a computer or include a computer. An output unit 232 is connected to the signal processing unit 228. In the simplest case, the output unit 232 can be a screen that displays, for example, a force measured by the force transducer 226. The output unit 232 is coupled to the signal processing unit 228 via a data connection 234. The data connection 234 can be wired or wireless. Furthermore, an electric tool 236, for example, a cordless screwdriver, can be coupled to the signal processing unit 228 by means of a data connection 238. The data connection 238 is wired or wireless.

[0113] The functionality of the transport securing device 214A is explained below with reference to Figs. 3 and 4 as well as Fig. 5, which describes a force profile of a force F measured by the force transducer 226 over a path w along the z-direction z.

[0114] Figure 4 shows the optical system 200A in transport state Z2. In transport state Z2, the first component 202 is fixed to the second component 204 such that the first component 202 is secured against relative movement with respect to the second component 204 during transport of the optical system 200A. To move the optical system 200A from the operating state ZI to the transport state Z2, the transport lock 214A is moved along the z-direction z relative to the second component 204. This can be done by screwing the transport lock 214A into the receiving section 216. This screwing in of the transport lock 214A can be done either manually or with the aid of an electric tool 236 as previously mentioned.

[0115] As mentioned previously, neither the end stop elements 210, 212 nor the spring element 224 contact the first component 202 in operating state ZI. If the transport lock 214A is now moved along the z-direction z towards the first component 202, a gap between the spring element 224 and the first component 202 is initially bridged. This gap is labeled with a path wl in Fig. 5. During the path wl, the movement of the transport lock 214A is forceless, so the force sensor 226 does not measure any force F during the path wl.

[0116] As soon as the spring element 224 contacts the first component 202, the spring element 224 is compressed over a distance w2. During this compression, the first component 202 moves along the z-direction z in the direction of the end stop elements 210, 212. Once the first component 202 contacts the end stop elements 210, 212, these are also compressed, as illustrated in Fig. 5 by a distance w3. During the distance w3, the spring element 224 and the end stop elements 210, 212 are deformed and compressed by spring elasticity until a desired closing force FV is reached.

[0117] Once the locking force FV is reached, a user stops the movement of the transport lock 214A relative to the second component 204, for example, due to a signal output at the output unit 232. This signal can be, for example, acoustic or visual. If an electric tool 236, as previously mentioned, is used, it is automatically switched off when the locking force FV is reached. The locking of the first component 202 to the second component 204 is thus force-controlled. The optical system 200A can now be transported in transport state Z2.

[0118] If, for example, the force sensor 226 fails, the mechanical end stop 222, by contacting the second component 204, can prevent further movement of the transport lock 214A relative to the second component 204, thus reliably preventing damage to the first component 202. The signal processing unit 228 can also receive and evaluate sensor signals from the force sensor 226 during the transport of the optical system 200A. This allows, for example, verification after transport as to whether the closing force FV was exceeded during transport.

[0119] The application of the shutter force FV for positioning components 202 and 204 for transporting the optical system 200A is therefore not displacement-controlled, but directly force-controlled. The force sensor 226 displays the force F during the movement of the optical system 200A from the operating state ZI to the transport state Z2, so that the defined shutter force FV can be set.

[0120] Fig. 6 shows a schematic view of another embodiment of an optical system 200B. Fig. 7 shows another schematic view of the optical system 200B. Figs. 6 and 7 will be discussed simultaneously below.

[0121] The optical system 200B differs from the optical system 200A in its construction and function only in that the optical system 200B features an alternative design of the transport lock 214B. Unlike the transport lock 214A, the transport lock 214B is not force-controlled, but displacement-controlled. The transport lock 214B operates purely mechanically. Therefore, the transport lock 214B does not have a force transducer 226 as previously mentioned. The transport lock 214B has a base section 218 as previously mentioned, from which an engagement section 220 with a frontally attached spring element 224 extends.

[0122] The transport safety device 214B includes a spacer 240, which is disc-shaped. The spacer 240 is threaded onto the engagement section 220 and rests against the base section 218. The thickness d of the spacer 240 is calculated in advance such that the locking force FV can be achieved by displacement control.

[0123] The functionality of the transport securing device 214B is explained below with reference to Figs. 6 and 7 as well as Fig. 8, which describes a force profile of a force F over a path w along the z-direction z.

[0124] Initially, the optical system 200B is in the previously mentioned operating state ZI, in which neither the end-stop elements 210, 212 nor the spring element 224 contact the first component 202. To move the optical system 200B from the operating state ZI shown in Fig. 6 to a transport state Z2 shown in Fig. 7, the transport lock 214B is repositioned relative to the second component 204. This can be done by screwing the transport lock 214B into the receptacle cut 216.

[0125] As shown in Fig. 8, the transport locking device 214B initially travels a force-free path wl. As soon as the spring element 224 contacts the first component 202, the spring element 224 is compressed over a path w2. Subsequently, the end stop elements 210, 212 are also deformed elastically and thereby compressed, as shown in Fig. 8 with the aid of a path w3. The thickness d of the spacer 240 is dimensioned such that the locking force FV is reached after the path w3.

[0126] When the locking force FV is reached, the spacer 240 rests against the second component 204, in particular against the second part 208 of the second component 204. If an attempt is now made to move the transport lock 214B further relative to the second component 204, for example by screwing the transport lock 214B further into the receiving section 216, the force F remains constant, since a mechanical short circuit exists due to the contact of the spacer 240 with the second component 204.

[0127] The main difference between transport locks 214A and 214B lies in the fact that, in transport lock 214A, the locking force FV is not set indirectly via the displacement w, or in other words, via the thickness d of the spacer 240, but directly by the force F being measured by the force sensor 226. With the displacement-controlled transport lock 214B, it is necessary to consider the entire tolerance chain of the end stop elements 210 and 212, the second component 204, the first component 202, and the transport lock 214B when determining the thickness of the spacer 240. The tolerance of the thickness d of the spacer 240 must also be taken into account.

[0128] With the force-controlled locking mechanism using the transport lock 214A, this tolerance chain is of lesser importance. The displacement w of the transport lock 214A only needs to be designed to reliably provide sufficient force F. The required locking force FV can be directly controlled by monitoring a force-displacement signal from the force sensor 226.

[0129] Advantageously, the tolerance chain no longer needs to be considered with the 214A transport locking device. This also reduces the amount of data required from suppliers. The 240 spacer is no longer needed with the 214A transport locking device. Spacer routines with checks are eliminated. Component pairing via the tolerance chain is no longer present with the 214A transport locking device. The necessary locking force FV for locking components 202 and 204 for transporting the 200A optical system can be directly controlled with the 214A transport locking device.

[0130] Eliminating the spacer 240 results in cost savings. Specifically, calculation, assembly, inspection, components, measurements, and logistics are eliminated. The design and process are simplified for the transport securing device 214A. Pairing transport securing devices 214A or transport covers with specific first components 202 is no longer necessary. Certain transport securing devices 214A can be freely used in any optical system 200A.

[0131] Fig. 9 shows a schematic block diagram of a method for transporting the optical system 200A.

[0132] In the process, in step S1, the closing force FV is applied to the first component 202, thus securing the first component 202 to the second component 204. Meanwhile, in step S2, the closing force FV is measured, enabling the securing of the first component 202 to the second component 204 to be force-controlled. Subsequently, in step S3, the optical system 200A can be transported, with the first component 202 being secured against relative movement with respect to the second component 204 during transport by means of the closing force FV.

[0133] Step S1 is preferably performed manually or automatically based on sensor data concerning the closing force FV acquired during step S2. As mentioned previously, the sensor data is acquired using the force transducer 226 and evaluated using the signal processing unit 228. Step S1 can then be performed automatically using an electric tool 236 as mentioned previously.

[0134] Preferably, step S2 is performed during step S3. This means, in particular, that the shutter force FV can be continuously monitored during the transport of the optical system 200A. For example, it is possible to check whether the shutter force FV was exceeded during transport, in which case damage to the first component 202 might be expected.

[0135] Although the present invention has been described using exemplary embodiments, it can be defined in many ways.

[0136] REFERENCE MARK LIST

[0137] 1 Projection exposure system

[0138] 2 lighting systems

[0139] 3 light source

[0140] 4 Lighting optics

[0141] 5 object field

[0142] 6 Object level

[0143] 7 reticles

[0144] 8 label holders

[0145] 9 Reticle displacement drive

[0146] 10 Projection optics

[0147] 11 Image field

[0148] 12 Image plane

[0149] 13 wafers

[0150] 14 wafer holders

[0151] 15 wafer transfer drive

[0152] 16 Lighting radiation

[0153] 17 Collector

[0154] 18 Intermediate focus plane

[0155] 19 deflecting mirrors

[0156] 20 first faceted mirror

[0157] 21 first facet

[0158] 22 second faceted mirror

[0159] 23 second facet

[0160] 100 optical system

[0161] 102 optical element

[0162] 104 support frames

[0163] 106 sensor frames

[0164] 108 Coupling element 110 Fixed world

[0165] 112 Coupling element

[0166] 114 actuator unit

[0167] 116 Coupling element

[0168] 118 Coupling element

[0169] 120 Control and regulation unit

[0170] 200A optical system

[0171] 200B optical system

[0172] 202 Component

[0173] 204 Component

[0174] 206 Component

[0175] 208 Component

[0176] 210 End stop element

[0177] 212 End stop element

[0178] 214A Transport lock

[0179] 214B Transport securing device

[0180] 216 Recording e section

[0181] 218 B base section

[0182] 220 Intervention section

[0183] 222 End stop

[0184] 224 Spring element

[0185] 226 force transducers

[0186] 228 Signal processing unit

[0187] 230 data connection

[0188] 232 output units

[0189] 234 Data connection

[0190] 236 tools

[0191] 238 Data connection

[0192] 240 spacers d thickness

[0193] F force

[0194] FV locking force

[0195] ml mirror

[0196] M2 mirrors

[0197] M3 mirror

[0198] M4 mirrors

[0199] M5 mirror

[0200] M6 mirrors

[0201] Step 51

[0202] Step 52

[0203] 53 steps w path wl path w2 path w3 path x x-direction yy direction z z-direction

[0204] Z 1 Operating state

[0205] Z2 Transport condition

Claims

PATENT CLAIMS 1. Optical system (100, 200A) for a projection exposure system (1), comprising a first component (202), a second component (204), and a transport lock (214A) for applying a shutter force (FV) to the first component (202) in order to fix the first component (202) to the second component (204), so that the first component (202) is secured against relative movements with respect to the second component (204) during transport of the optical system (100, 200A), wherein the transport lock (214A) has a force sensor (226) for detecting the shutter force (FV), so that the fixing of the first component (202) to the second component (204) is force-controlled.

2. Optical system according to claim 1, wherein the first component (202) is arranged at least sectionally within the second component (204).

3. Optical system according to claim 1 or 2, wherein the first component (202) is an optical element (102), and wherein the second component (204) is a support structure which supports the first component (202).

4. Optical system according to one of claims 1 - 3, wherein the transport safety device (214A) is attached to the second component (204).

5. Optical system according to claim 4, wherein the locking force (FV) can be generated by making the transport lock (214A) movable relative to the second component (204).

6. Optical system according to one of claims 1 - 5, wherein the transport lock (214A) has a spring element (224) for applying the locking force (FV) to the first component (202).

7. Optical system according to one of claims 1 - 6, comprising end stop elements (210, 212) which limit a freedom of movement of the first component (202) relative to the second component (204).

8. Optical system according to claim 7, wherein the end stop elements (210, 212) are at least partially spring-elastic deformable.

9. Optical system according to claim 7 or 8, wherein the closing force (FV) acts on the end stop elements (210, 212).

10. Optical system according to one of claims 1 - 9, comprising a signal processing unit (228) for receiving and processing sensor signals from the force transducer (226).

11. Optical system according to claim 10, wherein the signal processing unit (228) is configured to receive and evaluate sensor signals from the force transducer (226) during the transport of the optical system (100, 200A).

12. Projection exposure system (1) with an optical system (100, 200A) according to one of claims 1 - 11.

13. Method for transporting an optical system (100, 200A) for a projection exposure system (1), comprising the following steps: a) Applying (Sl) a shutter force (FV) to a first component (202) of the optical system (100, 200A), such that the first component (202) is held at a) a second component (204) of the optical system (100, 200A) is fixed, b) the shutter force (FV) is detected (S2) so that the fixing of the first component (202) to the second component (204) is force-controlled, and c) the optical system (100, 200A) is transported (S3), wherein the first component (202) is secured against relative movement with respect to the second component (204) during transport by means of the shutter force (FV).

14. Method according to claim 13, wherein step a) is carried out manually or automatically based on sensor data concerning the shutter force (FV) detected during step b).

15. Method according to claim 13 or 14, wherein step b) is carried out during step c).

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