Projection exposure system for semiconductor lithography with a connecting element

Abstract

The invention relates to a projection exposure system (1,101) for semiconductor lithography, with at least one connecting element (40,50.1,50.2,60.1,60.2) for connecting two components of the projection exposure system (1,101), wherein the connecting element (40,50.1,50.2,60.1,60.2) has at least one first mechanical decoupling element (41,43,51,53.x,61,63.x) and at least one second decoupling element (41,43,51,53.x,61,63.x). The projection exposure system (1,101) is characterized by the fact that the first decoupling element (41,51,61) and the second decoupling element (43,53.x,63.x) decouple the same sections (86.1,86.2,86.3) of the connecting element (40,50.1,50.2,60.1,60.2) from each other.

Description

[0001] The invention relates to a projection exposure system for semiconductor lithography with a connecting element.

[0002] Energy, signals, and fluids are typically exchanged between the components of a semiconductor projection exposure system via connecting elements. One of the components can be an optical element, such as a mirror of the projection exposure system, which can optionally be positioned in at least three degrees of freedom to optimize image quality. The connecting elements represent a mechanical connection between the components, which can also transmit unwanted mechanical vibrations. Therefore, the connecting elements are typically designed such that only minimal static and dynamic forces can be transmitted from one component to another connected to it, thus ensuring maximum decoupled components.

[0003] The static force depends in particular on the static stiffness of the connecting element and the deflection of the two components relative to each other.

[0004] Like dynamic stiffness, dynamic force is frequency-dependent and is determined by the transmission properties of the connecting element at different frequencies, such as its natural frequency. In particular, the mass of the connecting element affects the transmission properties of the connecting element and thus the transmitted dynamic force at a specific frequency of a relative oscillation between two components. The resulting forces exerted by the connecting element across a frequency range and the resulting movements particularly influence the controllability of a positioning component and can lead to unstable control.

[0005] Particularly in fluid connection elements, the reaction of the connection elements to the internal pressure within the connection element is playing an increasingly important role. This includes the behavior under static operating pressure, but especially the transmission behavior during dynamic pressure fluctuations in the fluid, i.e., mechanical vibrations transmitted via the fluid.

[0006] The internal pressure in the fastener leads to parasitic forces and moments at the connections to the adjacent components, which are referred to below as pressure reaction loads. These depend in particular on the ratio of the angular to axial stiffness of the fasteners.

[0007] The metal bellows known from the prior art, designed as decoupling elements between the generally rigid tubular sections of the connecting element, have the disadvantage of their relatively low axial stiffness. The axial and angular stiffnesses of the bellows are coupled; stiffening the bellows in the axial direction would also increase the angular stiffness. This has the disadvantage that the static and dynamic transmission properties of the connecting element would deteriorate.

[0008] The object of the present invention is to provide a device which eliminates the described disadvantages of the prior art.

[0009] This object is achieved by a device having the features of independent claim 1. The subclaims relate to advantageous developments and variants of the invention.

[0010] A projection exposure system for semiconductor lithography according to the invention comprises at least one connecting element for connecting two components of the projection exposure system. The connecting element has at least one first mechanical decoupling element and at least one second decoupling element. According to the invention, the first decoupling element and the second decoupling element decouple the same sections of the connecting element from each other. In other words, the decoupling elements are arranged between the two sections in such a way that their stiffnesses act in combination; thus, the stiffnesses complement each other to form a jointly acting stiffness between the sections.This makes it possible, particularly in the case of fluid-carrying connecting elements, to advantageously influence not only the static and dynamic behavior of the connecting element itself, but also the static and dynamic behavior of the connecting element caused by internal pressure in the connecting element. The internal pressure is generated by a pressure difference between the inside and outside of the connecting element, which is why the term differential pressure is also used instead of the term internal pressure. The stiffness of the decoupling elements is designed in such a way that the effects of both the static and dynamic behavior of the connecting element as a mechanical connection between the components and the static and dynamic behavior caused by a change in the internal pressure in the connecting element on at least one component are reduced or completely avoided.

[0011] In particular, at least one decoupling element can be designed to be rigid in at least one predetermined direction. Rigid in this context means that the rigidity of the decoupling element is designed to be as high as possible or as rigid as necessary, taking into account the geometry and the technical properties of the material used, such as yield strength or fatigue strength.

[0012] In contrast, soft is to be understood as the minimum possible or necessary stiffness within the framework of the design of the geometry and the technical properties of the material used. This means, for example, that the ratio of angular to axial stiffness can be advantageously adjusted in such a way that the effects of the static and dynamic behavior of the connecting element on the components can be reduced and / or completely avoided. The ratio of angular to axial stiffness can, for example, range from 1 to 20 to 1 to 1000 or more. In particular, the ratio can have a significant influence on the effects of the static and dynamic properties of the connecting element when the internal pressure changes, whereby the static and dynamic transmission behavior of the connecting element itself does not necessarily have to be significantly changed.

[0013] Furthermore, the rigidly designed predetermined direction can correspond to the axial direction of the decoupling elements. This leads to the advantageous reduction in the ratio of angular to axial stiffness of the decoupling elements explained above. The axially rigid decoupling element can be monolithic, whereby the monolithic structure can be manufactured using both conventional manufacturing processes, such as turning, milling, waterjet cutting, and / or EDM, as well as additive manufacturing processes.

[0014] In a further embodiment, at least one decoupling element can decouple rotation in all directions perpendicular to the rigid direction. This can be achieved, for example, by decoupling in two orthogonally formed rotational degrees of freedom perpendicular to the rigid direction, as is the case in a universal joint. The joint axes of the two joints of the universal joint can intersect at a point, which ideally also corresponds to the centers of stiffness of the two decoupling elements. The universal joint can be manufactured using conventional manufacturing methods or, alternatively, using an additive process.

[0015] In a further embodiment, the first decoupling element and the second decoupling element can be arranged coaxially. A coaxial arrangement is based on the assumption of predominantly rotationally symmetrical decoupling elements that have a common longitudinal axis. A first decoupling element designed as a bellows can, for example, be arranged coaxially with a tubular universal joint.

[0016] In particular, the first decoupling element and the second decoupling element can have a common center of stiffness. By definition, the center of stiffness corresponds to the point through which the restoring forces of a system act (IS: 1893-2002) and is determined by the stiffnesses within the system. When considering the two decoupling elements as a single system, it is advantageous for the two decoupling elements to have a common, i.e., the same, center of stiffness, thereby advantageously avoiding parasitic forces and moments on the sections. In the case of pure rotation, the pivot point of the system, for example, a joint, can correspond to the center of stiffness of the system.

[0017] In a further embodiment, at least one decoupling element can be fluid-tight. The decoupling element can be designed, for example, as a bellows, hose, or sleeve. The bellows, which can be designed, for example, as a metal bellows or a metal bellows, has, due to its design, a comparatively high rotational stiffness about the longitudinal axis of the bellows, while the two other orthogonal rotational degrees of freedom and the lateral stiffness are comparatively low. In combination with a parallel universal joint, the rotational stiffness of the bellows can be advantageously combined with the comparatively high axial stiffness of the universal joint, despite the frequently low rotational stiffness about the rigid axis.The decoupling elements connected in parallel thus jointly decouple the two sections decoupled by the decoupling elements, with the predetermined rotational stiffness being contributed by the bellows and the predetermined axial stiffness by the universal joint. The other angular stiffnesses required for a predetermined decoupling can be comparatively soft in both the bellows and the universal joint.

[0018] In the case of a hose or a sleeve, however, the hose and sleeve can represent only one fluid-tight decoupling element that is flexible in all degrees of freedom, whereas the second decoupling element connected in parallel has the predetermined, comparatively high rigidity in at least one direction. In the case described above, the second decoupling element can have the high rigidities in the axial direction and in rotation about the same.

[0019] Furthermore, the decoupling element, which is rigid in at least one predetermined direction, can be arranged within the fluid-tight decoupling element. In the case of a decoupling element designed as a tubular universal joint, for example, the arrangement within a bellows can lead to a beneficial improvement in the flow behavior. Compared to a solution that only has a bellows, for example, the formation of vortex shedding at the diameter jump from the tube to the bellows can be advantageously avoided. The effects of the cuts in the tube required to form the joint are significantly smaller and can be neglected at the low flow velocities typically encountered during operation of the projection exposure system.

[0020] The axial rigidity of the universal joint also prevents elongation and thus potential damage to the bellows, allowing the maximum pressure in the connecting element to be increased. This can, for example, advantageously increase the temperature control performance. As an alternative to the universal joint, the decoupling element, which is rigid in at least one predetermined direction, can also be designed as a joint rod, which can be held, for example, by mounts connected to the bellows flange via struts. The decoupling elements arranged in the fluid are expediently made of a corrosion-resistant material, such as stainless steel.

[0021] In a further embodiment, the decoupling element, which is rigid in at least one predetermined direction, can be arranged outside the fluid-tight decoupling element. This element can in turn be designed as a universal joint, whereby the arrangement outside the fluid greatly simplifies the selection of materials suitable for the decoupling element. This has the advantage that even very complex geometries, which are produced, for example, by an additive manufacturing process, can be used.

[0022] Furthermore, the rotational degree of freedom around the longitudinal axis of at least one decoupling element can be rigidly designed. This has the advantage that potentially occurring parasitic forces and moments can cause no or only negligible rotation of the decoupling elements around their longitudinal axis. This also prevents a shift in the center of stiffness, thus minimizing parasitic forces and moments on the components due to a static or dynamic change in the internal pressure.

[0023] In a further embodiment, the decoupling element, which is rigid in a predetermined direction, can be retrofitted in such a way that it can be arranged in addition to an already existing fluid-tight decoupling element between the same sections of the connecting element.

[0024] In particular, the retrofittable decoupling element can be designed in at least two parts. The two or more parts can be connected, for example, by a clamp. This has the advantage that existing systems can be retrofitted on-site.

[0025] In a further embodiment, the connecting element can have at least one damping element. This has the advantage that, in particular, the dynamic transmission functions of the connecting element can be damped.

[0026] In particular, the damping element can be integrated into the decoupling element, which is rigid in at least one predetermined direction. This has the advantage that no additional installation space is required for fixing an independent damper to the connecting element.

[0027] Alternatively, the damping element can be arranged in a damper independent of the decoupling elements. The damping elements can be designed, for example, as button dampers or as O-rings, with the damping element being arranged between two surfaces moving relative to each other. The damper can be designed such that the damping is predominantly based on the material damping of a material used for the damping element.

[0028] Furthermore, the damper can also be designed as a tuned mass damper, whereby a comparatively high damping effect can be achieved, in particular for a predetermined frequency.

[0029] In the following, embodiments and variants of the invention are explained in more detail with reference to the drawings. Fig. 1 schematically shows in meridional section a projection exposure system for EUV projection lithography, Fig. 2 schematically shows in meridional section a projection exposure system for DUV projection lithography, Fig. 3 a connecting element known from the prior art, Fig. 4a,b embodiments of a detail of a connecting element according to the invention, Fig. 5 shows a further embodiment of a detail of a connecting element according to the invention, Fig. 6a,b further embodiments of a detail of a connecting element according to the invention, Fig. 7 a model of a connecting element according to the invention for calculating the static and dynamic transmission properties of the connecting element according to the invention, and Fig. 8 a diagram comparing the transfer function of pressure reaction loads at the connections to pressure changes in the connecting element for a connecting element known from the prior art and the connecting element according to the invention.

[0030] In the following, with reference to the Fig. 1 describes, by way of example, the essential components of a projection exposure system 1 for microlithography. The description of the basic structure of the projection exposure system 1 and its components is not intended to be limiting.

[0031] One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system. In this case, the illumination system does not include the light source 3.

[0032] A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9.

[0033] In the Fig. 1 shows a Cartesian xyz coordinate system for explanation. The x-direction is perpendicular to the plane of the drawing. The y-direction is horizontal and the z-direction is vertical. The scanning direction is in the Fig. 1 along the y-direction. The z-direction runs perpendicular to the object plane 6.

[0034] The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0035] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0036] The radiation source 3 is an EUV radiation source. The radiation 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 has, in particular, a wavelength in the range between 5 nm and 30 nm. The radiation source 3 can be a plasma source, for example, an LPP source (laser produced plasma) or a DPP source (gas discharged produced plasma). It can also be a synchrotron-based radiation source. The radiation source 3 can be a free-electron laser (FEL).

[0037] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (GI), i.e., at angles of incidence greater than 45° relative to the normal direction of the mirror surface, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0038] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector 17, and the illumination optics 4.

[0039] The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugated to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which are also referred to below as field facets. Of these facets 21, Fig. 1 only some examples are shown.

[0040] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

[0041] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also 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 A1.

[0042] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction.

[0043] In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 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 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 A1, EP 1 614 008 B1, and US Pat. No. 6,573,978.

[0044] 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.

[0045] The second facets 23 can also be macroscopic facets, which can, for example, be round, rectangular, or hexagonal, or alternatively facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0046] The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

[0047] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (fly's eye integrator).

[0048] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugated to a pupil plane of the projection optics 10. In particular, the pupil facet mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0049] 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 before the object field 5.

[0050] In a further embodiment of the illumination optics 4 (not shown), a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which transmission optics 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 illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (GI mirrors, grazing incidence mirrors).

[0051] The illumination optics 4 has in the version shown in the Fig. 1, after the collector 17 there are exactly three mirrors, namely the deflection mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

[0052] In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

[0053] The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is usually only an approximate imaging.

[0054] The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0055] In the Fig. In the example shown in Figure 1, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 is a doubly obscured optic. 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.

[0056] Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0057] The projection optics 10 has a large object-image offset in the y-direction 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 can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

[0058] The projection optics 10 can, in particular, be anamorphic. It has, in particular, different magnifications βx, βy in the x- and y-directions. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, + / - 0.125). A positive magnification β means imaging without image inversion. A negative sign for the magnification β means imaging with image inversion.

[0059] The projection optics 10 thus leads to a reduction in the ratio 4:1 in the x-direction, i.e. in the direction perpendicular to the scanning direction.

[0060] The projection optics 10 results in a reduction of 8:1 in the y-direction, i.e. in the scanning direction.

[0061] Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions, for example, with absolute values ​​of 0.125 or 0.25, are also possible.

[0062] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 5 and the image field 11 can be the same or can vary depending on the design of the projection optics 10. Examples of projection optics with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0063] Each of the pupil facets 23 is assigned to exactly one of the field facets 21 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the field facets 21. The field facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to them.

[0064] The field facets 21 are each imaged onto the reticle 7 by an associated pupil facet 23, superimposed on one another, to illuminate the object field 5. The illumination of the object field 5 is, in particular, as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0065] By arranging the pupil facets, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the pupil facets that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting.

[0066] A likewise preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

[0067] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below.

[0068] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0069] The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the pupil facet mirror 22. When the projection optics 10 images the center of the pupil facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined distance of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in spatial space. In particular, this surface exhibits a finite curvature.

[0070] It is possible that the projection optics 10 have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, 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.

[0071] In the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 1, the pupil facet mirror 22 is arranged in a surface conjugated to the entrance pupil of the projection optics 10. The field facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflection mirror 19.

[0072] The first facet mirror 20 is arranged tilted to an arrangement plane which is defined by the second facet mirror 22.

[0073] Fig. 2 shows schematically in meridional section a further projection exposure system 101 for DUV projection lithography, in which the invention can also be used.

[0074] The structure of the projection exposure system 101 and the principle of imaging is comparable to that in Fig. 1 described structure and procedure. Identical components are provided with a 100 Fig. 1 raised reference numerals, the reference numerals in Fig. So 2 start with 101.

[0075] In contrast to a Fig. 1, due to the longer wavelength of the DUV radiation 116 used as useful light in the range from 100 nm to 300 nm, in particular from 193 nm, refractive, diffractive and / or reflective optical elements 117, such as lenses, mirrors, prisms, cover plates and the like, can be used in the DUV projection exposure system 101 for imaging or for illumination.The projection exposure system 101 essentially comprises an illumination system 102, a reticle holder 108 for receiving and precisely positioning a reticle 107 provided with a structure, by means of which the later structures on a wafer 113 are determined, a wafer holder 114 for holding, moving and precisely positioning this wafer 113 and a projection lens 110 with a plurality of optical elements 117, which are held via mounts 118 in a lens housing 119 of the projection lens 110.

[0076] The illumination system 102 provides DUV radiation 116 required for imaging the reticle 107 on the wafer 113. A laser, a plasma source, or the like can be used as the source for this radiation 116. The radiation 116 is shaped in the illumination system 102 via optical elements such that the DUV radiation 116, upon impinging on the reticle 107, exhibits the desired properties with regard to diameter, polarization, wavefront shape, and the like.

[0077] The structure of the subsequent projection optics 101 with the lens housing 119 does not differ in principle from that in Fig. 1 and is therefore not described further.

[0078] Fig. Figure 3 shows a fluid-conducting connecting element 30 known from the prior art. This comprises two connections 31.1, 31.2, which are connected to two components (not shown) via corresponding interfaces. The components can, for example, be components of a Fig. 1 described projection exposure system 1, such as a mirror M3 through which fluid flows for temperature control and a support structure which is in the Fig. 1 is not shown. The connecting element 30 serves to supply and discharge the temperature control fluid to and from the mirror M3, wherein the connecting element is also connected to the support structure.

[0079] The connecting element 30 further comprises decoupling elements designed as bellows 32.1, 32.2, 32.3, 32.4, which reduce or even completely prevent the transmission of static and / or dynamic mechanical disturbances from the support structure to the mirror M3. Fig. In the embodiment shown in Figure 3, two bellows 32.1, 32.4 are arranged between the connections 31.1, 31.2 and a first section 36.1 and a third section 36.3 of the connecting element 30, respectively, with the two sections 36.1, 36.3 being designed as straight tubes. Furthermore, two bellows 32.2, 32.3 are arranged between the first section 36.1 and the third section 36.3, respectively, and an arcuate second section 36.2 arranged between the two.

[0080] The connecting element 30 is in the Fig. 3 is shown with dashed lines with an applied differential pressure p between inside and outside the connecting element 30 of zero bar and with solid lines with a differential pressure p of one bar. Due to the different sized surfaces on the inner radius and outer radius, on which the differential pressure p acts, a resulting force F is produced on the outside of the second section, designed as a quarter bend 36.2. D It is clearly visible that the quarter arch 36.2 is formed by the force F D migrates from its original position in the drawing plane into the xz-plane due to the axially and angularly comparatively soft bellows 31.1, 31.2, 31.3, 31.4.

[0081] For a more detailed explanation of the cause of the so-called pressure reaction loads F caused at the connections 31.1, 31.2 DL , M DLThe connecting element 30 is additionally shown as a replacement diagram, which serves as a basis for static and dynamic calculations of the pressure reaction loads F DL , M DL The sections 36.1, 36.2, and 36.3 are shown as simple lines, whereas the bellows 32.1, 32.2, 32.3, and 32.4 are each represented by an axial spring 33.x, a torsion spring 34.x, and a damping element 35.x. The springs 33.x have an axial stiffness k axial , the rotation springs 34.x an angular stiffness k ang and the attenuator has an attenuation d.

[0082] If the connecting element 30 is subjected to a differential pressure p, a force F acts as described above at the apex of the quarter bend 36.2 D , which is divided into two forces F Dz , F Dx can be broken down into sections 36.1 and 36.3, each aligned parallel to the x-axis and z-axis.

[0083] The forces F D , FDz , F Dx are in the Fig. 3 as dashed arrows, where F D is calculated as follows: FD=π4di2∗p with d i = Inner diameter of connecting element.

[0084] Furthermore, the differential pressure p exerts a force F on the bellows B , which in the Fig. 3 are shown as dotted arrows, as follows: FB=π4(dm2−di2)∗p

[0085] These include: d m = Average diameter of the bellows p = differential pressure, which corresponds to the pressure difference between the environment and inside the connecting element.

[0086] The two forces F D , F B cause pressure reaction loads in the form of forces F at the connections 31.1, 31.2 DL and moments M DL , which in the Fig. 3 are shown as dashed arrows. The pressure reaction loads FDL , M DL can be calculated as a function of the forces F D , F B and the ratio of the angular to the axial stiffness k ang / k axial of the bellows 32.1, 32.2, 32.3, 32.4. The smaller the ratio k ang / k axial the smaller the pressure reaction loads F DL , M DL . FDL,MDL=f(kangkax,FD,FB)

[0087] The Fig. 3 forces F DLz , F DLx , F Dz , F Bx , F Bz and the moment M DLy . are based on a so-called open model. This means that the connecting element 30 is open at its ends, i.e., not closed, for example, by a cover. This results in both the forces F acting in the system caused by the differential pressure p at the quarter bend 36.2 Dx , F Dzas well as their reaction forces F of equal magnitude Dx , F Dz at the open ends of the connecting element. This has the advantage that the forces F leading to the deflection of the connecting element 30 D become visible, which would not be the case in a closed system with a lid, since in this case the forces within the system already cancel each other out and are therefore not visible at the supports of connections 31.1, 31.2. A closed system therefore only considers the forces measurable at connections 31.1, 31.2, without taking into account the forces F acting within the system. D The same applies to the bellows forces F B , which also act at the respective connections to sections 36.1, 36.2, 36.3, i.e., within the system and therefore not visible in a closed system. The pressure reaction loads F DL , M DLare the reaction loads caused by the restoring forces of the bellows 36.1, 36.2, 36.3, 36.4 caused by the deflection of the connecting element 30 on the fixed connections 31.1, 31.2.

[0088] Due to the symmetrical design of the connecting element 30, the Fig. 3 marked pressure reaction loads F DL , M DL at the connections 31.1, 31.2, so that the connecting element 30 is in equilibrium.

[0089] When calculating such an open system, the values ​​given in the Fig. 3 on the lower left side shown connection 36.1 a bearing force F acting on it z , which is represented by a dash-dot-dot line, from the difference between the pressure force F Dz the open end and the pressure reaction load F DLz . The bearing force F x corresponds to the pressure reaction force F DLx . The bearing force Fy is zero in the symmetrical embodiment shown.

[0090] The bellows 36.x, which are relatively soft in the axial direction, lead to an elongation of both legs, whereby the bellows 36.x in the legs are predominantly elongated, whereby the second section 36.2 as in the Fig. 3. This evasive movement leads not only to an elongation but also to a tilting of the bellows 36.1, 36.2, 36.3, 36.4, whereby axial and lateral forces F Bz , F Bx which are caused at the connection 31.1 to the pressure reaction loads in the form of an axial force F DLz , in the form of a lateral force F DLx and one moment M DLy contribute.

[0091] Fig. Figure 4a shows a first embodiment of a decoupling module 40 with a first decoupling element designed as a bellows 41 and a second decoupling element designed as a rod decoupling element 43, as can be used in a connecting element 80.1 according to the invention. The two decoupling elements 41, 43 thus connect the same sections 86.1, 86.2 to each other.

[0092] The bellows 41 corresponds to a bellows 32.x known from the state of the art ( Fig. 3) and has a flange 42.1, 42.2 on both sides for connection to sections 86.1, 86.2 of the connecting element 80.1. Sections 86.1, 86.2 correspond to sections 36.1, 36.2 ( Fig. 3).

[0093] On the inner surfaces of the flanges 42.1, 42.2, three struts are arranged each, of which only the struts 44.1 and 44.2 as well as 44.3 and 44.4 are visible due to the sectional view, each of which holds a receptacle 45.1, 45.2. The receptacles 45.1, 45.2 accommodate a joint rod 46, which has a tapered portion 47 in its center. The tapered portion 47 is designed such that the axial stiffness is maximum for a predetermined angular stiffness. With a suitable design, the axial stiffness can be increased compared to a decoupling module 32.x designed merely as a bellows ( Fig. 3) can be increased by a factor in the range of 40 to 60 without causing a significant increase (factor 0.5 to 2) in the angular stiffness. The rod decoupling 43 thus acts for the bellows 41 similarly to a tension rod, so that the elongation of the bellows 41 under pressure is advantageously avoided. In the case of a second section designed as a quarter bend 86.2 (see Fig. 3) to a smaller movement of the second section 86.2 in the yz-plane, which also reduces the angular deflection of the decoupling modules 40, which in turn reduces the pressure reaction loads FDL, MDL at the connections 31.1, 31.2 ( Fig. 3) can be advantageously reduced.

[0094] The effect of the rod decoupling element 43 as a tie rod also allows the connecting element 80.1 to be subjected to a higher pressure. This is possible because the elongation of the bellows 41, which limits the maximum possible pressure, and the resulting plastic deformation, is minimized or completely avoided by the tie rod.

[0095] The bellows 41, in turn, has a high torsional rigidity, so that the two decoupling elements 41, 43 complement each other advantageously with regard to the effective directions of their rigidities.

[0096] The material of the rod decoupling element 43 can be selected such that no chemical interactions, such as corrosion, occur with the fluid. For example, with ultrapure water, which is commonly used as the fluid, stainless steel is a suitable material for the rod decoupling element 43.

[0097] The bellows 41 and the rod decoupling 43 are in the Fig. 4a, they are arranged coaxially around a common axis 48 and have the same pivot point 49. This advantageously reduces or even completely eliminates parasitic forces when the bellows 41 and the rod decoupling device 43 tilt.

[0098] The higher axial stiffness causes the natural frequencies of the connecting element 80.1 to be shifted towards higher frequencies, as can be seen from the Fig. 7b will be explained in more detail. The higher natural frequencies, for example, lead to a greatly reduced influence of the pressure reaction loads F DLz , F DLx and moments M DLy to a position control of the mirror M3.

[0099] Fig. Fig. 4b shows a further embodiment of a decoupling module 50.1 with a first decoupling element designed as a bellows 51 and a second decoupling element designed as a cardan joint 53.1, as can be used in a connecting element 80.2 according to the invention, wherein, where appropriate, corresponding elements with respect to the Fig. 4a are designated by reference numerals increased by 10. The two decoupling elements 51, 53.1 thus connect the same sections 86.1, 86.2. The bellows 51 is in the Fig. 4b, so that the internal universal joint 53.1 can be seen. This comprises a first joint formed from a pair of leaf springs 54.1 running parallel to the common axis of the decoupling elements 51, 53.1, wherein in the illustration of the Fig. 4b, the second leaf spring, which is offset to the rear in the plane of the drawing, is covered by the leaf spring 54.1. Furthermore, the universal joint 53.1 comprises a second joint formed from a second pair of leaf springs 54.2, 54.3, which are arranged offset by 90° to the first pair 54.1. The leaf springs 54.1, 54.2, 54.3 are arranged in the Fig. 4b is manufactured monolithically, i.e. formed from a piece of pipe by corresponding cutouts 55.1, 55.2, 55.3.

[0100] The two joints allow decoupling around any axis perpendicular to the common axially aligned axis 58.

[0101] The pivot point 59 of the two joints is identical to the pivot point of the bellows 51, so that no parasitic forces and / or moments are exerted on the connections 32.1, 32.2 ( Fig. 3) caused.

[0102] The axial stiffness achieved by the cardan joint 53.1 is comparable to that in the Fig. 4a described rod decoupling 43. The angular stiffnesses are also in a comparable range.

[0103] The universal joint 53.1 comprises a stop 56 and a connecting surface 57 for fastening the bellows 51 to the universal joint 53.1. The bellows 51 is pushed onto the universal joint 53.1 up to the stop 56 and is connected in a fluid-tight manner to the stop 56 and to the connecting surface 57, for example by laser welding.

[0104] As an alternative to the material connection, the connection can also be made using a form-fitting or force-fitting connection technology.

[0105] Due to its arrangement inside the bellows 51, the universal joint 53.1 becomes part of the fluid-carrying connecting element 80, thus being flowed through by the fluid. This has the advantage that the vortex shedding that typically occurs in the bellows 51 (without the universal joint 53.1) above a certain flow velocity can be at least reduced or even completely avoided at the same or higher flow velocities. This allows both higher pressures and higher flow velocities to be achieved, in addition to the axial stiffening acting as a tie rod for the bellows 41, 51 and the fluid-carrying universal joint 53.1.

[0106] Fig. 5 shows a further embodiment of a decoupling module 60.1 with a first decoupling element designed as a bellows 61 and a second decoupling element designed as a cardan joint 63.1, as can be used in a connecting element 80.3 according to the invention, wherein, where appropriate, corresponding elements with respect to the Fig. 4b are designated by reference numerals increased by 10. The two decoupling elements 61, 63.1 in turn connect the sections 86.1, 86.2. The bellows 61 is in the Fig. 5 is shown transparently, so that the external cardan joint 63.1, which is shown in section in the embodiment shown, can be seen. The cardan joint 63.1 is functionally identical to the one shown in the Fig. 4b shown cardan joint 53.1.

[0107] The bellows 61 is, as in the Fig. 4b is welded to the sections 86.1, 86.2 of the connecting element 80.3.

[0108] The connection of the universal joint 63.1 to the sections 86.1, 86.2 is designed such that through holes 67.1, 67.2, 67.3 with threads 76.1, 76.2, 76.3 are formed in the universal joint 63.1. Furthermore, slots 77 are formed in the universal joint 63.1, tilted by 90° to the through holes 67.1, 67.2, 67.3. The universal joint 63.1 is clamped to the sections 86.1, 86.2 by screws 79.1, 79.2, 79.3 in the area next to the flanges 62.1, 62.2 of the bellows 61.

[0109] Alternatively, the universal joint 63.1 can also be bolted to sections 86.1 and 86.2. In this case, threads are provided in sections 86.1 and 86.2.

[0110] In a further embodiment, the universal joint 63.1 can be formed in two parts, for example in the form of two half shells. The cutting surfaces of the Fig. In the sectional view shown in Figure 5, joining surfaces 70.1, 70.2 correspond to one of two half-shells, whereby only the rear half-shell projecting into the plane of the drawing is shown in the Fig. 5. The half-shells are connected to each other at the joining surfaces 70.1, 70.2. After aligning the two half-shells, they are connected by clamps 71.1, 71.2. This has the advantage that the universal joint 63.1 can be used with an existing connecting element 30 ( Fig. 3) can be easily retrofitted from the prior art, i.e. without dismantling or replacing elements of the connecting element 30. The clamping would function identically to the method described above through through holes 78.1, 78.2, 78.3 formed in the clamps 71.1, 71.2.

[0111] The arrangement of the universal joint 63.1 outside the fluid has the advantage that a larger selection of materials is available, since no increased requirements are placed on corrosion resistance.

[0112] The extension of the first axially soft bellows 41, 51, 61 with an axially stiff and angularly soft second decoupling element 43, 53.1, 63.1 with a defined pivot point results in the bellows 41, 51, 61 contributing the fluid tightness as its only necessary function. Therefore, the bellows can optionally be replaced, where possible, by a hose or a sleeve made of an elastomer or another material with a high material damping. This has the advantage that the natural frequencies can be damped in addition to the shift to higher frequencies. Alternatively, damping can also be designed as an independent component of the connecting element 80.1, 80.2, 80.3 or, as in the Fig. 6a and Fig. 6b explained in detail in the cardan joints 53.1, 63.1.

[0113] Fig. 6a shows a decoupling element of a decoupling module 50.2 designed as a cardan joint 53.2 in a sectional view, which is predominantly identical to the one shown in the Fig. 4b shown cardan joint 53.1, which is why the designation of the identical elements in the Fig. 6a where it was sensible to omit it.

[0114] Furthermore, the universal joint 53.2 comprises receiving areas 72.1, 72.2 for receiving damping elements designed as button dampers 73.1, 73.2, which advantageously dampen movements of the universal joint 53.2. The Fig. The damping elements 73.1, 73.2 shown in Figure 6a dampen an angular movement about the rotational axis 82, which is oriented perpendicular to the common axial axis 58, and a linear movement in the direction of the axis 83, which is oriented perpendicular to the axes 58, 82. Two additional damping elements for damping an angular movement about the axes 83 and in the direction of the linear axis 82 are not shown or visible in the sectional view. The damping elements 73.1, 73.2 are made, for example, of FKM or another elastomer and have a comparatively high material damping, which advantageously dampens dynamic movements in particular.

[0115] Fig. 6b shows a decoupling element of a decoupling module 60.2 designed as a cardan joint 63.2 in a sectional view, which is predominantly identical to the one shown in the Fig. 5 shown cardan joint 63.1, which is why the designation of the identical elements in the Fig. 6b where it was sensible to omit it.

[0116] Furthermore, the universal joint 63.2 comprises receiving areas 74.1, 74.2 for receiving damping elements designed as O-rings 75.1, 75.2, which advantageously dampen a movement of the universal joint 53.2. Fig. The O-ring 75.1 shown in Figure 6b dampens an angular movement about the axis 84 and a linear movement along the axis 85 perpendicular thereto. The O-ring 75.2, on the other hand, dampens an angular movement about the axis 85 and a linear movement along the axis 84. The O-rings 75.1, 75.2 are made, for example, from an elastomer such as FKM or another suitable material and have a comparatively high material damping, whereby dynamic movements in particular are advantageously damped.

[0117] The Fig. 6a, Fig. The damping elements shown in Figure 6b can alternatively be arranged in independent dampers with their own kinematics, which damp the relative movements of sections 86.1, 86.2, 86.3 of the connecting element 80.1, 80.2, 80.3 independently of the decoupling element used. This also allows a connecting element 80.1 to be damped with a second decoupling element designed as a rod decoupling element 43.

[0118] Fig. Figure 7 shows a model of a connecting element 80.4 for calculating the effect of a higher axial stiffness, as used in the decoupling modules 40, 50.1, 60.1 of the Fig. 4a, Fig. 4b, Fig. 5 is designed to influence the transmission behavior of the differential pressure p to the pressure reaction loads F DLx , F DLy , F DLz The model represents the connecting element 80.4 with the sections 86.1, 86.2, 86.3, whereby in comparison to the Fig. 3, a decoupling element between the third section 86.1 and the second section 86.2 was omitted in the model. Fig. 8 shown transfer functions of the ratio of the bearing forces F x , F y , F z to the differential pressure p over the frequency correspond to the three axes of the Fig. 7 at connection 81.1. The support forces F x , F y , F z are with the in the Fig. 3 explained open system, so that the bearing forces F x , F y the two pressure reaction loads F DLx , F DLy correspond and F z the bearing reaction of connection 81.1, the force F caused by the differential pressure D as well as the pressure reaction load F DLz The moments also shown are in the Fig. 8 not shown.

[0119] Fig. 8 shows a diagram of the three transfer functions of the ratio of the three bearing forces F x , F y , F z to the differential pressure p over the frequency, whereby the diagrams represent a qualitative statement of the change due to the increase in axial stiffness in the decoupling module 40, 50.1, 60.1. On the ordinate of the diagram is the ratio of bearing forces F x , F y , F z to the differential pressure p in N / bar and the frequency in Hz is plotted on the abscissa, with the axes having a logarithmic representation.

[0120] The dashed curves correspond to the transfer functions of the state-of-the-art with a 32.x decoupling module with a comparatively low axial stiffness. The solid curves correspond to the transfer functions with a 40, 50.1, and 60.1 decoupling module with an axial stiffness increased by a factor of 40 to 60 compared to the state-of-the-art.

[0121] The diagram shows three pairs of curves 90.1, 91.1, 92.1, 93.1, 94.1, 95.1, where the even reference numerals correspond to the transfer functions based on the axially soft connecting elements 30 and the odd ones are assigned to the axially stiff connecting elements 80.1, 80.2, 80.3 and which each correspond to a direction x, y, z.

[0122] The Fig. 8 top pair of curves 90.1, 91.1 shows the transfer function of the bearing force F caused in the axial direction z. Curves 90.1 and 91.2 run almost parallel and with almost the same value up to the first resonance 90.2. The deviation of the bearing force F z the connection 81.1 from the force F caused by the pressure Dz deviates due to the deflection of the quarter arch 86.1 in the xz-plane by the amount of the pressure reaction load F DLx (= bearing force F x ). Since this force is significantly smaller in magnitude than the force acting in the z-direction, the difference in the logarithmic representation is minimal. The increase in the first natural frequency is clearly visible in the distance between the first resonance 90.2 of the first curve 90.1 and the first resonance 91.2 of the second curve 91.1.

[0123] The second pair of curves 92.1, 93.1 shows the bearing force F x . The significant decline in bearing force F xFor the axially rigid connecting element 40, 50.1, 60.1, the spacing between curves 92.1 and 93.2 across the entire frequency range clearly shows the increase in the first resonance 92.2 and 93.2 for the axially rigid connecting element 40, 50.1, and 60.1. As with the pair of curves 90.1 and 91.1, this pair of curves 92.1 and 93.1 also clearly shows the increase in the first resonance 92.2 and 93.2 for the axially rigid connecting element 40, 50.1 and 60.1.

[0124] The third pair of curves 94.1, 96.1 shows the bearing force F y Here, too, a significant reduction in the corresponding pressure reaction load F DLy For the axially rigid connecting element 40, 50.1, 60.1, this is clearly visible due to the spacing of curves 94.1, 94.2 across the entire frequency range, although the absolute values ​​are very small. As with the curve pairs 90.1, 91.1, 92.1, 93.1, the increase in the first resonance 94.2, 95.2 for the axially rigid connecting element 40, 50.1, 60.1 is also clearly visible in this curve pair 92.1, 93.1. List of reference symbols 1 projection exposure system 2 Lighting system 3 Radiation 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 plane 13 wafers 14 wafer holders 15 Wafer relocation drive 16 EUV radiation 17 Collector 18 Intermediate focal plane 19 Deflecting mirrors 20 facet mirrors 21 facets 22 facet mirrors 23 facets 30 connecting element 31.1, 31.2 Connection component 32.1-32.4 Decoupling element 33.1-33.4 Spring 34.1-34.4 Torsion spring 35.1-35.4 dampers 36.1-36.3 Section Connecting element 40 bellows element 41 Bellows 42.1,42.2 flange 43 Rod decoupling 44.1-44.4 Strut 45.1,45.2 Recording 46 Joint rod 47 Rejuvenation 48 Axial axis 49 Pivot point 50 decoupling element 51 bellows 52.1,52.2 Flange 53.1-53.3 Cardan joint 54.1-54.2 Leaf spring 55.1-55.3 Free cut 56 stop 57 connecting surface 58 Axial axis 59 Pivot point 60 decoupling element 61 bellows 62.1,62.2 flange 63 Cardan joint 64.1-64.3 Leaf spring 65.1-65.3 Free cut 66.1,66.2 Connecting flange 67.1-67.3 Through hole 68 Axial axis 69 Pivot point 70.1,70.2 Joining surface (two-part design 71.1,71.2 clamp 72 Damper mount 73 button dampers 74 Damper mount 75 O-ring 76.1-76.3 thread 77 slot 78.1, 78.2 Through hole clamp 79 Screw 80.1-80.4 Connecting element 81.1,81.2 Connection component 86.1-86.3 Section Connecting element 87 screws 90.1,90.2 Transfer function / resonance N / bar x SDT 91.1,91.2 Transfer function / resonance N / bar x New 92.1,92.2 Transfer function / resonance N / bar y SDT 93.1,93.2 Transfer function / resonance N / bar y New 94.1,94.2 Transfer function / resonance N / bar z SDT 95.1,95.2 Transfer function / resonance N / bar z New 101 Projection exposure system 102 Lighting system 107 reticles 108 reticle holders 110 Projection optics 113 wafers 114 wafer holders 116 DUV radiation 117 optical element 118 versions 119 lens housings M1-M6 mirrors F x,y,z Bearing forces open system F Dx,z Force due to pressure in the connecting element F Bx,z Power on the bellows F DLx,y,z Force pressure reaction load on the connection flange M DLx,y,z Moment pressure reaction load on the connection flange QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2008 009 600 A1 [0041, 0045] US 2006 / 0132747 A1

[0043] EP 1 614 008 B1

[0043] US 6,573,978

[0043] DE 10 2017 220 586 A1

[0048] US 2018 / 0074303 A1

[0062] Cited non-patent literature

[0000] IS: 1893-2002

[0016]

Claims

[1] Projection exposure apparatus (1,101) for semiconductor lithography, comprising at least one connecting element (40,50.1,50.2,60.1,60.2) for connecting two components of the projection exposure apparatus (1,101), wherein the connecting element (40,50.1,50.2,60.1,60.2) has at least one first mechanical decoupling element (41,51,61) and at least one second decoupling element (43,53.x,63.x), characterized by that the first decoupling element (41,51,61) and the second decoupling element (43,53.x,63.x) decouple the same sections (86.1,86.2,86.3) of the connecting element (40,50.1,50.2,60.1,60.2) from each other. [2] Projection exposure system (1,101) according to claim 1, characterized by that at least one decoupling element (43,53.x,63.x) is rigid in at least one predetermined direction. [3] Projection exposure system according to claim 2, characterized bythat the rigid predetermined direction corresponds to the axial direction of the decoupling element (43,53.x,63.x). [4] Projection exposure apparatus according to one of claims 2 or 3, characterized by that at least one decoupling element (43,53.x,63.x) decouples the rotation about all directions perpendicular to the rigid direction. [5] Projection exposure system (1,101) according to one of the preceding claims, characterized by that the first decoupling element (41,51,61) and the second decoupling element (43,53.x,63.x) are arranged coaxially [6] Projection exposure system (1, 101) according to one of the preceding claims, characterized by that the first decoupling element (41,51,61) and the second decoupling element (43,53.x,63.x) have a common center of stiffness. [7] Projection exposure system (1,101) according to one of the preceding claims, characterized bythat at least one decoupling element (41,51,61) is fluid-tight. [8] Projection exposure system (1,101) according to claim 7, characterized by that the decoupling element (43,53.x,63.x) which is rigid in at least one predetermined direction is arranged within the fluid-tight decoupling element (41,51,61). [9] Projection exposure system (1,101) according to claim 7, characterized by that the decoupling element (43,53.x,63.x) which is rigid in at least one predetermined direction is arranged outside the fluid-tight decoupling element (41,51,61). [10] Projection exposure system (1,101) according to one of the preceding claims, characterized by that the rotational degree of freedom about the longitudinal axis (48,58,68) of at least one decoupling element (41,43,51,53.x,61,63.x) is rigid. [11] Projection exposure system (1,101) according to one of claims 2 to 10, characterized bythat the decoupling element (43,53.x,63.x) which is designed to be rigid in a predetermined direction is designed to be retrofittable in such a way that it can be arranged in addition to an already existing fluid-tight decoupling element (41,51,61) between the same sections (86.1,86.2,86.3) of the connecting element (40,50.1,50.2,60.1,60.2). [12] Projection exposure system (1,101) according to claim 11, characterized by that the retrofittable decoupling element (43,53.x,63.x) is formed in at least two parts. [13] Projection exposure system (1,101) according to one of the preceding claims, characterized by that the connecting element (40,50.1,50.2,60.1,60.2) has at least one damping element (73.x,75.x). [14] Projection exposure system (1,101) according to claim 13, characterized by that the damping element (73.x,75.x) is integrated into the decoupling element (43,53.x,63.x) which is stiff in at least one predetermined direction. [15] Projection exposure system (1,101) according to claim 13, characterized by that the damping element (73.x,75.x) is arranged in a damper independent of the decoupling elements (41,43,51,53.x,61,63.x).

Images