Projection exposure system with a connecting element and method for designing the connecting element

Abstract

The invention relates to a projection exposure system (1, 101) for semiconductor lithography, comprising a connecting element (30, 40) for connecting two components of the projection exposure system (1, 101), wherein the connecting element (30, 40) has a tube (31, 41). The projection exposure system (1, 101) is characterized in that the tube (31, 41) has at least one stiffening element (32, 42.1, 42.2, 42.3). The invention further relates to a method for designing a connecting element (30, 40) for a projection exposure system (1, 101) for semiconductor lithography, wherein the connecting element (30, 40) is designed to connect two components of the projection exposure system (1, 101) and wherein the connecting element (30, 40) has a hose (31, 41), comprising the following method steps: - Determination of the mechanical vibrations occurring in a fluid flowing through the hose (31,41), - Determining the arrangement of at least one stiffening element (32,42.1,42.2,42.3) on the hose (31,41).

Description

[0001] The invention relates to a projection exposure system with a connecting element and a method for designing the connecting element.

[0002] Projection exposure systems for semiconductor lithography are subject to extremely high image quality requirements to ensure the desired microscopic structures are produced with as few defects as possible. In a lithography or microlithography process, an illumination system illuminates a photolithographic mask, also known as a reticulum. The light passing through or reflecting from the mask is projected by a projection optic onto a substrate (e.g., a wafer) coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection optic. This transfers the structural elements of the mask onto the photosensitive coating of the substrate. The light used to image the mask onto the wafer is also referred to as the useful light of the projection exposure system.The requirements for positioning the image on the wafer and the intensity of the useful light are increased with each new generation, resulting in a higher heat load on the optical elements.

[0003] In cases of high heat load, it can be advantageous to temper the optical elements, particularly those designed as mirrors, in EUV projection exposure systems (i.e., systems operating with electromagnetic radiation with wavelengths between 1 nm and 120 nm, especially at 13.5 nm) using water cooling supplied by a so-called water cabinet. Water-cooled mirrors and / or lenses can also be used in DUV projection exposure systems (i.e., systems operating with electromagnetic radiation with wavelengths between 120 nm and 300 nm). The mirrors incorporate fluid channels through which tempered water flows, thereby dissipating heat from the optical surface, i.e., the mirror surface struck by the light used to image the structural elements. Any dynamic or...Mechanical excitation must be avoided to prevent disruption of the imaging processes of the projection system. This excitation can be transmitted both via the supply and return lines of the tempered water, also known as structural mechanics, and via the fluid itself, i.e., the propagation of mechanical vibrations as pressure waves in the water, also known as water-pipe acoustics.

[0004] Water pipe acoustics can be caused by the flow of the fluid itself, i.e., the movement of the fluid within the pipe, generating excitations known as flow-induced vibrations. Mechanical excitations can also be transmitted independently of the fluid flow; these are called transferred excitations. Transferred excitations are caused, for example, by mechanical vibrations of supporting structures and transmitted to the fluid via the connections of the supply and discharge pipes to these structures. Both flow-induced and transferred vibrations lead to changes in the position of the mirrors and deformations of their optical surface, with both disturbances negatively impacting the image quality of the projection system.

[0005] To reduce the described effects of flow-induced and transferred vibrations, hereinafter referred to as acoustic vibrations, a number of measures are already taken in the prior art, such as optimizing the fluid channels in the mirror, as well as the supply lines from the water cabinet to the mirror. Due to the materials' tendency to outgas excessively and / or the risk of leakage from mechanical damage, plastic hoses are avoided as supply lines wherever possible. In cases where decoupling is necessary in the connecting elements, sections of plastic hose are enclosed by metal bellows, or a metal bellows without a hose is used as the decoupling element. To dampen the acoustic vibrations, additionally complex devices with passive (Helmholtz resonator) and active (actuator / sensor systems for reducing acoustic vibrations) components are used.This has the disadvantage that the installation space required for the components must be provided and / or the manufacturing costs are negatively affected.

[0006] The object of the present invention is to provide a device that eliminates the disadvantages of the prior art described above. A further object of the invention is to provide a method for designing a connecting element of a projection exposure system for reducing acoustic vibrations.

[0007] This problem is solved by a device and a method having the features of the independent claims. The dependent claims relate to advantageous embodiments and variants of the invention.

[0008] A projection exposure system according to the invention for semiconductor lithography comprises a connecting element for connecting two components of the projection exposure system, wherein the connecting element has a tube. The projection exposure system is characterized in that the tube has at least one stiffening element. For the purposes of the invention, a tube is defined by an outer sheath that is elastic compared to a pipe, allowing both radial expansion and compression of the tube and vibration of the tube about its longitudinal axis, such as a string of a musical instrument. Due to the radial expansion of the tube, mechanical vibrations transmitted via the fluid, the so-called acoustic vibrations, can be reduced by the material damping that occurs during expansion and contraction of the tube.A further reduction of acoustic vibrations can be achieved by a suitable design of the natural frequencies and modes, which can reduce acoustic vibrations at least in individual frequencies or frequency ranges.

[0009] In a first embodiment, the stiffening element can be rigidly connected to the hose, at least in sections. For example, the stiffening element can be connected to the hose at three points or surfaces arranged equidistantly around the circumference of the contact surface of the stiffening element.

[0010] In particular, the stiffening element can be connected to the hose around its entire circumference. This has the advantage that, in the event of compression of the hose, no peel forces act on the connection points in the radial direction, thus increasing the service life of the connection.

[0011] Furthermore, the two segments of the hose created by the stiffening element can be of different lengths. The length of the segments influences the hose's tendency to collapse under a radial external force. The segment length also affects the natural frequencies and modes of the segment in the radial and longitudinal directions, as previously explained. Thus, different lengths of the two segments result in two different damping effects on the fluid. According to the invention, an existing hose, arranged between two connecting elements, is divided into two segments by the at least one stiffening element. A hose closed by two connecting elements, therefore, does not have a segment according to the invention. This segment is only formed by the arrangement of at least one stiffening element as described in the invention.

[0012] In a further embodiment, the distance between at least two stiffening elements or between a connecting element and a terminal element can be designed such that complete collapse of the segment under operational loads can be prevented. Complete collapse, as defined in the invention, refers to contact between different areas of the inner surface of the hose, in particular a resulting permanent "bonding." The operational loads, which, according to the invention, are defined as the pressure difference between the areas inside and outside the hose, can, for example, be in the range of up to 101.3 kPa.

[0013] In a preferred embodiment, the stiffening element can be arranged on the outer circumference of the hose. The arrangement on the outer circumference has the advantage that the stiffening element cannot negatively affect the flow of the fluid flowing through the hose.

[0014] In particular, the hose can be arranged inside a tube. This has the advantage that the hose is protected from mechanical damage, especially during the assembly of the projection exposure system. Furthermore, the tube prevents outgassing from the hose from reaching the optical elements of the projection exposure system. This also prevents, for example, organic outgassing from coming into contact with the useful light used to image the structures onto a wafer, thus advantageously preventing the breakdown of the outgassing and any resulting further contamination of the optical elements.

[0015] Furthermore, the stiffening element can be designed as a spacer between the hose and the pipe. This ensures that the hose is at least frictionally connected via the spacers, and axial movement of the hose along its longitudinal axis can advantageously be avoided. A fixed distance between the stiffening elements, or between a connecting element and a stiffening element, can ensure a stable natural frequency of the segment formed by the stiffening element.

[0016] In another embodiment, the distance between the hose and the pipe can be designed such that acoustic vibrations can be dampened by elastic expansion of the hose. The distance can determine the maximum expansion of the hose, thereby allowing both the damping effect through material damping and the reduction of mechanical vibrations at specific frequencies to be adjusted.

[0017] As an alternative to arranging the stiffening element on the outer circumference of the hose, the stiffening element can be arranged on the inner circumference of the hose. This is particularly advantageous if a surrounding pipe can be omitted and / or the stiffening element has no negative impact on the fluid flowing in the pipe.

[0018] In another embodiment, the stiffening element can be integrated into the hose. This integration can be achieved, for example, by inserting stiffening elements during the hose manufacturing process. Alternatively, the stiffening element can be created by locally increasing the wall thickness of the hose material, whereby the wall thickness in the area of ​​the stiffening element can be significantly greater than the nominal wall thickness. The wall thickness depends, among other things, on the geometry of the hose, the number and spacing of the stiffening elements, and the pressure differential, and must be selected appropriately for the specific application.

[0019] Furthermore, the hose can have varying wall thicknesses within a segment. These are only slight compared to the stiffening elements described above, but can, for example, enable damping of different frequencies or individual pressure pulses within a segment.

[0020] An inventive method for designing a connecting element for a projection exposure system for semiconductor lithography, wherein the connecting element is designed to connect two components of the projection exposure system and wherein the connecting element has a hose, comprises the following method steps: - Determination of the mechanical vibrations occurring in a fluid flowing through the hose. - Determination of the arrangement of at least one stiffening element on the hose.

[0021] The mechanical vibrations can be determined as pressure changes or as transfer functions, i.e., the frequency-dependent change or amplification of the input pressure relative to the output pressure of a connecting element. The data determined in this way can then be used to define the arrangement of the stiffening elements, i.e., the length of the segments.

[0022] Furthermore, at least one segment can have a predetermined natural frequency. Vibration of the segment at its natural frequency can, in addition to pure material damping, also reduce individual frequencies of the acoustic vibrations.

[0023] In particular, the natural frequency can be configured such that it resonates with a frequency of a mechanical vibration determined in the first process step. The resonance can be designed to reduce the acoustic vibration, i.e., to exhibit a gain of significantly less than 1 in the transfer function. This reduction can affect not only a single frequency but also a frequency range, with the reduction varying in magnitude for the individual frequencies within that range.

[0024] Furthermore, the air gap between the hose and a pipe that at least partially surrounds it can be designed in such a way that the hose is protected from plastic deformation and / or bursting. The distance between the hose and the pipe (air gap) can therefore advantageously be designed such that the damping effect through material damping is increased by a maximum air gap, while simultaneously preventing damage to the hose. The air gap can also accommodate a laterally occurring natural frequency, i.e., vibration of the segment.

[0025] Exemplary embodiments and variants of the invention are explained in more detail below with reference to the drawing. The drawing shows Fig. 1. Schematic representation in meridional section of a projection exposure system for EUV projection lithography, Fig. 2 schematically in meridional section a projection exposure system for DUV projection lithography, Fig. 3a,b a first embodiment of the invention, Fig. 4 a further embodiment of the invention, and Fig. 5 an alternative design of a device.

[0026] The following will first refer to the Fig. 1. The essential components of a projection exposure system 1 for microlithography are described as an example. The description of the basic structure of the projection exposure system 1 and its components is not intended to be restrictive.

[0027] One embodiment of a lighting system 2 of the projection exposure system 1 has, in addition to a radiation source 3, a lighting 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 lighting system. In this case, the lighting system does not include the light source 3.

[0028] A reticule 7 located in the object field 5 is illuminated. The reticule 7 is held by a reticule holder 8. The reticule holder 8 can be moved, particularly in one scanning direction, via a reticule displacement drive 9.

[0029] In the Fig. Figure 1 shows a Cartesian xyz coordinate system for illustrative purposes. The x-direction runs perpendicular to the plane of the drawing. The y-direction runs horizontally, and the z-direction runs vertically. The scan direction runs in the Fig. 1 along the y-direction. The z-direction runs perpendicular to the object plane. 6.

[0030] 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.

[0031] 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, 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.

[0032] Radiation source 3 is an EUV radiation source. Specifically, radiation source 3 emits EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation has a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be a plasma source, for example, an LPP source (laser-produced plasma) or a DPP source (gas-discharged produced plasma). It can also be a synchrotron-based radiation source. Radiation source 3 can be a free-electron laser (FEL).

[0033] 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 hyperboloid reflective surfaces. The at least one reflective surface of the collector 17 can be illuminated with the illumination radiation 16 at grazing incidence (GI), i.e., with angles of incidence greater than 45° relative to the normal direction of the mirror surface, 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.

[0034] 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.

[0035] 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 are also referred to as field facets in the following. Of these facets 21, the following are in the Fig. 1 only some examples are shown.

[0036] 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.

[0037] 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.

[0038] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction.

[0039] 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.

[0040] 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.

[0041] 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 A1 in this regard.

[0042] The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

[0043] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (Fly's Eye Integrator).

[0044] 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 pupil 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.

[0045] 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.

[0046] In another embodiment of the illumination optics 4, not shown, a transmission optic can be arranged in the beam path between the second facet 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 behind the other in the beam path of the illumination optics 4. The transmission optic can in particular comprise one or two mirrors for normal incidence (NI mirrors) and / or one or two mirrors for grazing incidence (GI mirrors).

[0047] The illumination optics 4 has in the version shown in the Fig. Figure 1 shows exactly three mirrors after the collector 17, namely the deflecting mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] In the Fig. In the example shown, the projection optics 10 comprise six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have an aperture for the illumination radiation 16. The projection optics 10 are a double-obscured optic. The projection optics 10 have 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.

[0052] 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.

[0053] 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.

[0054] The projection optics 10 can be anamorphic. In particular, they have 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 indicates a projection without image inversion. A negative magnification β indicates a projection with image inversion.

[0055] The projection optics 10 thus lead to a reduction in the x-direction, that is, in the direction perpendicular to the scan direction, in a ratio of 4:1.

[0056] The projection optics 10 lead to a reduction of 8:1 in the y-direction, that is, in the scan direction.

[0057] Other magnification ratios are also possible. Magnification ratios with the same sign and absolute values ​​in the x and y directions, for example with absolute values ​​of 0.125 or 0.25, are also possible.

[0058] 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, 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 are known from US 2018 / 0074303 A1.

[0059] Each pupil facet 23 is assigned to exactly one of the field 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 by means of the field facets 21. The field facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to each of them.

[0060] The field facets 21 are each superimposed on the reticulum 7 by an associated pupil facet 23 to illuminate the object field 5. 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.

[0061] The illumination of the entrance pupil of the projection optics 10 can be geometrically defined by the arrangement of the pupil facets. By selecting the illumination channels, in particular the subset of 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.

[0062] 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.

[0063] 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.

[0064] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0065] The entrance pupil of the projection optics 10 cannot be precisely illuminated by the pupil facet mirror 22. When the projection optics 10 image 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 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.

[0066] 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.

[0067] 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 plane conjugate 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 deflecting mirror 19.

[0068] The first faceted mirror 20 is arranged at an angle to an arrangement plane defined by the second faceted mirror 22.

[0069] Fig. Figure 2 schematically shows in meridional section another projection exposure system 101 for DUV projection lithography, in which the invention can also be applied.

[0070] The design of the projection exposure system 101 and the principle of the imaging process are comparable to that in Fig. The structure and procedure described in section 1 are identical. The components are 100 times larger than the others. Fig. 1 raised reference numeral denotes the reference numerals in Fig. So, 2 starts with 101.

[0071] Unlike one such as in Fig. Due to the longer wavelength of the DUV radiation 116 used as useful light in the range of 100 nm to 300 nm, in particular of 193 nm, refractive, diffractive and / or reflective optical elements 117, such as lenses, mirrors, prisms, end plates and the like, can be used in the DUV projection exposure system 101 for imaging or illumination in the DUV projection exposure system 101 for imaging or illumination.The projection exposure system 101 essentially comprises a lighting system 102, a reticule holder 108 for receiving and precisely positioning a reticule 107 provided with a structure, by which the subsequent 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 several optical elements 117, which are held in a lens housing 119 of the projection lens 110 via mounts 118.

[0072] The illumination system 102 provides DUV radiation 116 required for imaging the reticulum 107 on the wafer 113. A laser, a plasma source, or the like can be used as the source for this radiation 116. In the illumination system 102, the radiation 116 is shaped by optical elements such that, upon striking the reticulum 107, the DUV radiation 116 exhibits the desired properties with respect to diameter, polarization, wavefront shape, and the like.

[0073] The construction of the following projection optics 101 with the lens housing 119 differs in principle from that in, except for the additional use of refractive optical elements 117 such as lenses, prisms, end plates. Fig. The structure described in section 1 is therefore not described further.

[0074] Fig. Figure 3 shows a detail of a connecting element 30 according to the invention, designed as a hose 31. The connecting element 30 can be used to connect individual components, such as a temperature-controlled lighting system 2, 102 ( Fig. 1, Fig. 2) a projection exposure system 1, 101 and a water cabinet for the provision and preparation of a temperature control fluid.

[0075] The hose 31 has a stiffening element 32 at one point, which is arranged on the hose between the two connecting elements 37.1, 37.2. The elements 32, 37.1, 37.2 are each firmly connected to the outside of the hose 31 via a contact surface 34.1, 34.2, 34.3. The stiffening element 32 divides the hose 31 into two segments 35.1, 35.2, which have lengths l S1 , l S2 exhibit the lengths l S1 , l S2 Segments 35.1 and 35.2 can be individually configured.

[0076] The hose 31 is connected to a pipe 36 via interfaces 33.1, 33.2, 33.3, which correspond to the outer surfaces of the elements 32, 37.1, 37.2 ( Fig. 3b) connected.

[0077] The stiffening element 32 further shortens the free hose length, i.e., the distance between the two connection elements 37.1, 37.2 of the hose 31. This advantageously prevents the hose 31 from collapsing completely in the event of negative pressure within the hose or positive pressure outside the hose 31, i.e., from opposite sections of the inner surface coming into contact. Depending on the magnitude and duration of the applied negative pressure, this can lead to the hose 31 sticking together and thus to a complete collapse of the hose 31. The segment lengths I S1 , I S2 are therefore designed to be as long as possible so that contact between opposing areas of the inner surface of the hose 31 is advantageously avoided under the expected negative pressures.

[0078] Fig. Figure 3b shows the connecting element 30 with the hose 31 connected to the pipe 36 via the stiffening element 32 and the connecting elements 37.1, 37.2. The thickness of the elements 32, 37.1, 37.2 defines a distance d. RS between the outer surface of the hose 31 and the inner surface of the pipe 36, thereby protecting the hose 31 from damage by local plastic deformation or bursting under excessive pressure. The distance d SR The diameter of the hose 31 is chosen to be large enough to allow it to expand when a pressure wave occurs in the fluid flowing through it. The expansion of the hose 31 in the region of segments 35.1 and 35.2 dampens the pressure wave due to the material damping of the hose.

[0079] If segments 35.1 and 35.2 are designed such that their natural frequency corresponds to a frequency of, or the natural frequency of, hose 31 corresponds to the frequency of, a pressure fluctuation transmitted in the fluid, the phase-shifted vibrations of hose 31 can cancel out or significantly reduce the pressure fluctuation at that frequency. However, this effect is considered subordinate to the material damping due to the difficulty in predicting pressure fluctuations in the fluid and the fact that the natural frequency of hose 31 cannot be subsequently adjusted.

[0080] The tube 36 also serves to protect the hose 31 from mechanical damage, particularly during the assembly of the projection exposure system. In the case of using a connecting element in a projection exposure system 1, 101 ( Fig. 1, Fig. 2) the tube 36 can also hold other components, in particular the optical elements of the projection optics 10 ( Fig. 1) Protect against outgassing from hose 31.

[0081] Fig. Figure 4 shows a further embodiment of a detail of a connecting element 40, in which three stiffening rings 42.1, 42.2, 42.3 are arranged inside the hose 41 and connected to it via the contact surfaces 44.1, 44.2, 44.3. The connecting elements are in the Fig. 4 not shown. This embodiment can be used in particular in cases where the outgassing of the hose 31 is not critical, such as in the area outside the optical systems of a projection exposure system 1,101.

[0082] Alternatively, the stiffening elements can also be integrated into hose 31 or achieved by a partially significantly increased wall thickness.

[0083] Fig. Figure 5 shows a further embodiment of a connecting element 50, not claimed here, which eliminates the same disadvantages of the connecting elements known from the prior art, with features that differ from the embodiments described above. The connecting element 50 comprises a damping element designed as a hose 51, wherein the hose 51 is arranged in the fluid flow, i.e., is surrounded by the fluid. The damping effect of pressure fluctuations occurring in the fluid is based, as described above, mainly on the deformation of the hose 51, i.e., on the material damping of the material used for the hose 51.

[0084] The hose 51 is connected via an adapter 58 to a flange 57 formed on the pipe 56, the adapter 58 being connected to the flange 57 at an interface 53.

[0085] The hose 51 is sufficiently protected from sticking together due to contact between opposing areas of the inner surface of the hose 51 under overpressure by the internal pressure present in the closed volume of the hose 51. The gas volume, acting as a compressed spring, in conjunction with the restoring force stored in the elastically deformed material of the hose 51, is sufficient in the vast majority of cases to break any possible adhesions.

[0086] At the same time, a system-related maximum increase in pressure in the hose 51 by 1 bar, namely during a complete evacuation of the pipe 56, is also known, whereby plastic deformation or bursting of the hose 51 can be easily avoided by a corresponding limitation of the internal pressure.

[0087] Alternatively to the one in the Fig.In the case of hose 51 shown in Figure 5, the damping element can also be made from a solid material. This can be adapted to the predetermined requirements by selecting a suitable material and stiffness. Sufficient elasticity and high material damping are important, as these significantly influence the damping effect of the damping element, as mentioned above. Reference symbol list 1 Projection exposure system 2 Lighting system 3. Radiation source 4 Lighting optics 5 object field 6 Object level 7 reticles 8 label holders 9 Reticle displacement drive 10 Projection optics 11 Image field 12 Image plane 13 wafers 14 wafer holders 15 wafer transfer drive 16 EUV radiation 17 Collector 18 Intermediate focus plane 19 deflecting mirrors 20 faceted mirrors 21 facets 22 faceted mirrors 23 facets 30 connecting element 31 hose 32 Stiffening element 33 Interface to the pipe 34 Contact surface with hose 35.1, 35.2 Distance between connecting elements 36 pipe 37.1, 37.2 Connection element 40 connecting element 41 hose 42.1-42.3 Stiffening element 44 Contact surface with hose 45.1, 45.2 segments 50 connecting element 51 hose 53 Pipe interface 56 pipe 57 Flange 58 Adapter flange 101 Projection exposure system 102 Lighting system 107 reticles 108 label holders 110 Projection optics 113 wafers 114 wafer holders 116 DUV radiation 117 optical element 118 versions 119 lens bodies M1-M6 mirrors I S1 , I S2 Segment length d RS Pipe-hose distance QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2008 009 600 A1 [0037, 0041] US 2006 / 0132747 A1

[0039] EP 1 614 008 B1

[0039] US 6,573,978

[0039] DE 10 2017 220 586 A1

[0044] US 2018 / 0074303 A1

[0058]

Claims

[1] Projection exposure system (1,101) for semiconductor lithography, with a connecting element (30,40) for connecting two components of the projection exposure system (1,101), wherein the connecting element (30,40) has a hose (31,41), characterized by that the hose (31,41) has at least one stiffening element (32,42.1,42.2,42.3). [2] Projection exposure system (1,101) according to claim 1, characterized by that the stiffening element (32,42.1,42.2,42.3) is firmly connected to the hose (31,41) at least in sections. [3] Projection exposure system (1,101) according to claim 1, characterized by that the stiffening element (32,42.1,42.2,42.3) is connected to the hose (31,41) over its entire circumference. [4] Projection exposure system (1,101) according to one of the preceding claims, characterized bythat two segments (35.1,35.2,45.1,45.2) of the hose (31,41) created by a stiffening element (32,42.1,42.2,42.3) are of different lengths. [5] Projection exposure system (1,101) according to claim 4, characterized by that the distance between at least two stiffening elements (32,42.1,42.2,42.3) or at least one connecting element (37.1,37.2) and one stiffening element (32) is designed such that a complete collapse of the segment (35.1,35.2,45.1,45.2) is prevented under operational loads. [6] Projection exposure system (1,101) according to one of the preceding claims, characterized by that the hose (31,41) is arranged within a pipe (36). [7] Projection exposure system (1,101) according to one of the preceding claims, characterized by that the stiffening element (32,42.1,42.2,42.3) is arranged on the outer circumference of the hose (31,41). [8] Projection exposure system (1,101) according to claim 7, characterized by that the stiffening element (32,42.1,42.2,42.3) is designed as a spacer between the hose (31,41) and the pipe (36). [9] Projection exposure system (1,101) according to claim 8, characterized by that the distance between the hose (31,41) and the pipe (36) is designed such that damping of acoustic vibrations is effected by elastic expansion of the hose (31,41). [10] Projection exposure system (1,101) according to one of claims 1 to 6, characterized by that the stiffening element (32,42.1,42.2,42.3) is arranged on the inner circumference of the hose (31,41). [11] Projection exposure system (1,101) according to one of claims 1 to 9, characterized by that the stiffening element (32,42.1,42.2,42.3) is integrated in the hose (31,41). [12] Projection exposure system (1,101) according to one of claims 4 to 11, characterized bythat the hose (31,41) has varying wall thicknesses within a segment. [13] Method for designing a connecting element (30, 40) for a projection exposure apparatus (1, 101) for semiconductor lithography, wherein the connecting element (30, 40) is designed to connect two components of the projection exposure apparatus (1, 101) and wherein the connecting element (30, 40) has a hose (31, 41), comprising the following method steps: - Determination of the occurring mechanical vibrations of a fluid flowing through the hose (31,41), - Determination of the arrangement of at least one stiffening element (32,42.1,42.2,42.3) on the hose (31,41). [14] Method according to claim 13, characterized by that at least one segment (35.1,35.2,45.1,45.2) has a predetermined natural frequency. [15] Method according to claim 14, characterized bythat the natural frequency of the segment (35.1,35.2,45.1,45.2) resonates with a mechanical vibration occurring in a fluid. [16] Method according to one of claims 13 to 15, characterized by that an air gap (d RS ) between the hose (31,41) and a pipe (36) is designed such that the hose (31,41) is protected from plastic expansion and / or bursting.

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