Assembly for semiconductor apparatuses to suppress acoustic wave propagation within a semiconductor apparatus and semiconductor apparatus

Abstract

The invention relates to an assembly (70) for a fluid line (39,42,43) for a semiconductor apparatus (1,101) comprising at least one damping section (72) to damp acoustic vibrations within a fluid (79), the damping section (72) comprising a pipe (76) comprising a viscoelastic material, characterized in that the pipe comprising when filled with the fluid (79) a transfer factor (VD) smaller than 095, preferably smaller than 0.8, particularly preferred smaller than 0,4 at a roll-off frequency in the range of 0–3000 Hz, preferably in a range of 0-1000 Hz, particularly preferred in a range of 0–500 Hz. Additionally, the invention relates to a semiconductor apparatus (1,101), preferably a projections exposure apparatus (1,101), particularly preferred a EUV projection exposure apparatus (1) comprising at least one assembly (70) according to one the described embodiments. Furthermore, the invention also refers to a method for designing a pipe (76) for an assembly (70) for a fluid line (39,42,43) for a semiconductor apparatus (1,101) comprising at least one damping section (72) to damp acoustic vibrations within a fluid (79), the damping section (72) comprising the pipe (76) comprising a viscoelastic material the method comprising the following steps: - Determining a desired transfer factor VD and a desired roll-off frequency frolloff for a given fluid, - Determining a material frequency fmaterial based on the roll-off frequency frolloff and the transfer factor VD, - Determining the material and geometric parameters of the pipe (76) in such a way that the equation (A) applies, whereby (B).

Description

[0001] Assembly for semiconductor apparatuses to suppress acoustic wave propagation within a semiconductor apparatus and semiconductor apparatus

[0002] The present application claims the priority of the German patent application DE 10 2024 106 396.3 of March 06th, 2024, the content of which is fully incorporated by re- ference herein.

[0003] The invention relates to an assembly for semiconductor apparatuses and a semicon- ductor apparatus, particularly a projection exposure apparatus.

[0004] Projection exposure apparatuses for semiconductor lithography are highly dependent on the quality of the illumination of the object plane. The electromagnetic radiation used for illumination is generated by an illumination system and a light source, here- after referred to as the light source used. In the case of EUV lithography, the used light source is a comparatively complex plasma source, in which a plasma is gener- ated by laser irradiation of tin droplets, which emits electromagnetic radiation in the desired short wavelength frequency ranges. The radiation produced by this light source includes not only radiation of the wavelength of the light used, which in the case of an EUV projection exposure apparatus is in the range from 5 nm to 20 nm, in particular at 13.5 nm, but also radiation components of other wavelengths, such as IR radiation. The IR radiation is emitted by the laser to generate the plasma and is not intended to enter the optics of the illumination system or the projection optics unit, as it would otherwise heat up the optical elements, with adverse effects on image qual- ity. However, some IR light will enter the illumination system and the projection optics unit, increasing the heating of the mirrors during exposure. In the case of DUV lithog- raphy, the used light source is a laser source that produces used light with a wave- length between 100 nm and 300 nm, in particular 193 nm.

[0005] To enable higher throughput on projection exposure apparatuses, the power of the light source is increased, which leads to increased heating of the optical elements, in the case of EUV lithography mirrors, which can cause deformation of the mirrors, re- ducing the imaging quality due to imaging and overlay errors. To mitigate such heat- ing errors, optical elements are cooled directly using a fluid, preferably water. This solution comes with another issue, since the cooling water brings, besides mechani- cal vibrations via the piping system, acoustic vibrations in form of pressure fluctua- tions generated from various sources within the projection exposure apparatus to the mirrors. The acoustic vibrations, known as water line acoustics (WLA), are transmit- ted to the cooled components, particularly optical elements, leading to mechanical vi- brations and deformations of the optical element causing imaging and overlay errors. To address this issue, the acoustic vibrations need to be silenced before they reach the cooled optical elements and components.

[0006] The current state of the art for the suppression of WLA pressure fluctuations within the piping system are gas silencers, also known as Helmholtz resonators. In the res- onators, air acts as a spring for a resonant mass of water. To avoid interaction be- tween air and water, in particular the dissolution of the air in the water, a bellow or membrane can be employed to separate both fluids from each other. In order to meet the given maximum level of acoustic vibrations within the piping system and the given tolerances for imaging and overlay multiple silencers are used in series to be em- ployed before and after the mirrors. The placement of silencers in series has the dis- advantage, that it creates low-frequency pressure spikes, referred to as a sloshing mode, due to the resonating mass of water in the piping between two compliances (air stiffness in gas silencers). These low frequent pressure spikes can be corrected by active mirrors with active position control, but can especially cause imaging and overlay issues due to the excitation of passive mirrors. In addition, acoustic modes, i.e. standing waves, are created within the fluid due to acoustic impedance mismatch as well as in the silencer chamber, which result in high frequent pressure spikes. These again can lead to imaging and overlay errors also in active mirrors due to lim- its of the control bandwidth.

[0007] The object of the present invention is to provide an assembly which overcomes the above described disadvantages of the state of the art.

[0008] This object is achieved by an assembly having the features of independent claim 1 . The dependent claims relate to advantageous refinements and variants of the inven- tion. According to the invention, an assembly for a fluid line for semiconductor appara- tuses comprises at least one damping section to damp acoustic vibrations within a fluid filled into the fluid line. The damping section comprises a pipe comprising a vis- coelastic material. The assembly is characterized by the fact that the pipe comprising when filled with the fluid (79) a transfer factor (VD) smaller than 0.95, preferably smaller than 0.8, particularly preferred smaller than 0.4.

[0009] Particularly the roll-off frequency is in a range of 0-3000 Hz, preferably in a range of 0-1000 Hz, particularly preferred in a range of 0-500 Hz.

[0010] Viscoelasticity refers to a partially elastic, partially viscous material behavior. Vis- coelastic materials therefore combine characteristics of solids and liquids. The effect is dependent on time, temperature and frequency and occurs in polymer melts and solids such as plastics, but also in other materials. The elastic component generally causes spontaneous, limited, reversible deformation, while the viscous part generally causes a time-dependent, unlimited, irreversible deformation. The irreversible defor- mation will be reversible by the parallel orientation of the two effects. The elastic component will return into its original shape and the viscous component will follow. Therefore, the elastic part can be seen as a storage part of the material, storing the deformation energy, while the viscous part can be seen as the damping part, dissi- pating energy into heat within the material. The properties of the viscous and elastic components are different in different viscoelastic materials, leading to different char- acteristics, particularly damping properties. Additionally, the properties, e.g. Young’s Modulus, of the viscoelastic materials show a strong frequency dependency, which can among others be explained by the inertia of the viscous part of the material.

[0011] The viscoelastic material also has the advantage that due to its capability to also elastically deform under pressure turbulence and, consequently, the excitation of fluid induced vibrations in the flow within the pipe can be advantageously avoided. A fur- ther advantage regarding vibrations is the smooth surface of the viscoelastic pipe compared to an alternatively used rough bellow surface with all the corrugations which would otherwise cause turbulences. The viscoelastic properties of the pipe, which can be in the form of a viscoelastic hose, result in a frequency dependent and complex elasticity modulus (Young's modulus), whereas the real part E’ of the com- plex Young's modulus stands for storage of energy and the imaginary part E” of the complex Young's modulus stands for a loss of energy by dissipation. The ratio of E" / E' describes the loss factor q of the material, which defines the effectiveness of the damping of acoustic vibrations within the fluid. The viscoelastic material therefore can dissipate energy of the acoustic vibrations according to the loss factor q men- tioned above.

[0012] The dampening of the viscoelastic material supports a so-called roll-off effect which occurs due to the viscoelastic damping within the pipe wall. Depending on the geom- etry of the viscoelastic pipe, particularly the length L and wall thickness t of the vis- coelastic pipe and the properties of the material, particularly the Young's modulus, which will be complex for viscoelastic materials, a desired roll-off frequency can be targeted. The roll-off frequency is defined as the frequency at which the desired transfer factor shall be reached or after which the transfer factor of a transfer function of the pressure pout after and before pinthe pipe is below the transfer factor VD. For example, if the transfer factor VDis set to be at 0.37 « 1 / e the damping will be at ap- proximately 63%. For VDset to be at 0.9 the damping will be at approximately 90%.

[0013] The transfer factor VDdamps an incoming acoustic vibration in relation to the outgo- ing acoustic vibration, if the value of the transfer factor VDis below 1 and is defined by the following equation: whereby

[0014] Pout = pressure after pipe section Pin = pressure before pipe section fmaterial = material frequency f rolloff = Rolloff frequency.

[0015] VD= transfer factor.

[0016] The frequency fmaterial is derived after setting the desired transfer factor VDand the desired roll-off frequency froiioff by solving the equation above for fmaterial- f material Iri(Vp) * f rolloff

[0017] The material frequency fmateriai is used to determine the frequency dependent material parameters of the pipe, as described below.

[0018] 1 . Additionally, the material and geometric parameters of the pipe (76) are cho- sen at a desired roll-off frequency (froiioff) and a desired transfer factor (VD), when filled with the fluid (79), in a way, that the following equation applies: The above equation shows the proportional dependencies of the different parame- ters, which can be combined to define a roll-off parameter at a predetermined damp- ing effect as follows: whereby

[0019] Prolloff = Rolloff parameter

[0020] • The roll-off parameter proiioff can be in a range of preferably in a range of particularly preferred in a range of

[0021] In another embodiment of the invention, Young's modulus of the viscoelastic material can be in a range of 0.1 - 1000 MPa, preferably in a range of 0.1 - 400 MPa and par- ticularly preferably in a range of 0.1 - 50 MPa. These ranges will be feasible for damping the typical given acoustic vibrations transmitted in the fluid in a semiconduc- tor apparatus, particularly in a projection exposure apparatus. Typical excitations may be in a range of approx. + / - 15 kPa [0 - 3000 Hz], typically approx. + / - 7 kPa [0 - 3000 Hz],

[0022] Additionally, the loss factor within a frequency range of the viscoelastic material can be in a range of 0.1 - 3 [0 - 3000 Hz], preferably in a range of 0.5 - 2 [0 - 3000 Hz], particularly preferred in a range of 1 - 2 [0 - 3000 Hz], This enables a damping of the amplitudes in the critical frequency ranges by a factor of approx. 5 - 10000, prefer- ably by a factor of approx. 5 - 1000 and particularly preferred by a factor of 20 - 1000 in the critical frequency ranges of 0 - 3000 Hz, preferably the range of 0 - 1000 Hz and particularly preferred in the range of 0 - 500 Hz.

[0023] Furthermore, the inner diameter Di of the pipe (76) can be in a range of 1 -40 mm, preferably in a range of 2-25 mm, particularly preferred in a rage of 4-15 mm. Additionally, the wall thickness t of the pipe (76) can be in the range of 0.2-20 mm, preferably in the range of 0.2-15 mm, particularly preferred in the range of 0.5-10 mm.

[0024] Furthermore, the length L [mm] of the pipe (76) can be in the range of 10-2000 mm, preferably in the range of 10-1000 mm and particularly preferred in the range of 20- 500 mm.

[0025] In another embodiment, the damping section can comprise an outer pipe. The outer pipe can protect the pipe from mechanical contact minimizing the risk of damage dur- ing assembly.

[0026] Furthermore, the pipe and the outer pipe can at both ends be connected to pipe con- nectors of the assembly via pipe adapters, allowing the connection to Interfaces of a fluid line system within the semiconductor apparatus. The viscoelastic material, based on the elastic component, can advantageously also overcome positioning tol- erances of the interfaces within the semiconductor apparatus.

[0027] In another embodiment the volume between the inner pipe and the outer pipe enclos- ing the inner pipe can be closed. This can advantageously avoid outgassing of the viscoelastic material used within the inner pipe and / or of fluid, which can diffuse through the inner pipe due to the permeability of the used materials into an area com- prising optical elements of a semiconductor apparatus, particularly in projection expo- sure apparatuses.

[0028] Furthermore, the closed volume can comprise a compressible fluid.

[0029] In particular, it can comprise air, preferably extreme clean dry air (XCDA), nitrogen or helium. Air has the advantage that it is available within the semiconductor technol- ogy, comparatively low priced and has a comparatively low risk of damaging other components, especially the sensitive optical components, such as mirrors, within a projection exposure apparatus, in case of outgassing or accidental or faulty leakage.

[0030] Nitrogen has the advantage that it is defined by only one molecule, which reduces the risk of contamination compared to air comprising more than one kind of mole- cules. Helium has the advantage that it can be used for leak detection. Helium is also used in small quantity in projections exposure apparatuses, so availability will be given.

[0031] In case of a closed volume surrounding the inner pipe comprising a compressible fluid, the fluid will act like a spring, allowing the inner pipe to expand freely under acoustic vibrations, but also avoiding of contact to the outer, comparably stiffer pipe. The stiffness of the inner pipe and the stiffness of the surrounding volume will add to a combined stiffness, whereas the stiffness of the surrounding volume can be ne- glected in most cases.

[0032] In particular, the stiffness of the volume surrounding the inner pipe can be a factor of approx. 5 - 5000 smaller than the stiffness of the inner pipe, preferably a factor of ap- prox. 5 - 500 smaller than the stiffness of the inner pipe, particularly preferred a factor of approx. 5-100 smaller than the stiffness of the inner pipe. This reduces the impact of the surrounding volume on the damping abilities of the inner pipe.

[0033] In a further embodiment, the outer pipe can be flexible and / or stiff. In fact, the outer pipe is primarily used to avoid outgassing of the materials used for the inner pipe and is therefore needed within most parts of semiconductor apparatuses, in particular in projections exposure apparatuses.

[0034] In the context of the invention, flexible means that the stiffness of the pipe is de- signed to be as low as possible within the scope of the design and the technical prop- erties of the material used, such as yield strength or flexural fatigue strength, which is more likely to be applicable for the inner pipe. In contrast, stiff is to be understood as the greatest possible stiffness within the scope of the design and the technical prop- erties of the material used. Furthermore, the outer pipe can be designed as a corru- gated pipe, a bellow and / or pipe and comprising stainless steel and / or plastic and / or any feasible materials, particularly meeting the strict demands for cleanliness and outgassing within the semiconductor technology and semiconductor apparatuses, particularly in EUV projection exposure apparatuses.

[0035] In another embodiment of the invention, the distance between the inner pipe and the outer pipe can be designed in such a way, that the outer pipe prevents the inner pipe from expanding over a predefined volume. In other words, the outer pipe functions as an end stop defining the maximum volume of the inner pipe. This will reduce or even ban the risk of a bursting of the inner pipe, in particular also in case of malfunctions in the fluid line system for example during testing, qualification or putting the system into operation.

[0036] Furthermore, the fluid can comprise water, which preferably is used as a cooling fluid in semiconductor apparatuses.

[0037] In particular, the viscoelastic pipe can comprise one or more of butyl rubber (HR), chlorosulfonated polyethylene (CSM), epichlorohydrin rubber (ECO), polynorbonene rubber (PNR), ethylene-vinyl acetate rubber (EVA), acrylate rubber (ACM), ethylene propylene diene monomer (EPDM) and silicon. All materials show the desired char- acteristics for damping acoustic vibrations within the fluid.

[0038] According to the invention, a semiconductor apparatus, preferably a projection expo- sure apparatus, particularly preferred an EUV projection exposure apparatus, com- prises an assembly according to one of the above-described embodiments.

[0039] The idea of using a viscoelastic pipe for damping acoustic vibrations within a pipe section of a fluid line of a semiconductor apparatus in itself can be regarded an in- vention, particularly also without the additional aspect of a surrounding second pipe and independent of the properties of the second pipe as for example, if it is corru- gated and / or stiff and / or flexible.

[0040] Method for designing a pipe (76) for an assembly (70) for a fluid line (39,42,43) for a semiconductor apparatus (1 ,101 ) comprising at least one damping section (72) to damp acoustic vibrations within a fluid (79), the damping section (72) comprising the pipe (76) comprising a viscoelastic material the method comprising the following steps:

[0041] - Determining a desired transfer factor VD and a desired roll-off frequency frolloff for a given fluid.

[0042] - Determining a material frequency fmaterial based on the roll-off frequency frolloff and the transfer factor VD. - Determining the material and geometric parameters of the pipe (76) in such a way that the following equation applies:

[0043] Deriving of fmateriai based on the transfer factor VDand the roll-off frequency froiioff is explained above.

[0044] Given the transfer factor VD(=damping) and the roll-off frequency froiioff the material frequency fmateriai can be derived. After choosing a corresponding material the ma- terial parameters can be derived using the material frequency. Further the inner di- ameter and the wall thickness t can be determined leaving the length of the hose 76 as the not defined variable in the above equation.

[0045] Solving the equation for L will determine the corresponding length L of the hose 76 fulfilling the desired damping (transfer factor) at a desired frequency, the so-called roll-off frequency.

[0046] It is obvious to an expert in the field, that any of the material and geometric parame- ters, such as the wall thickness or the inner diameter of the hose 76, can be chosen to be the final parameter to be determined after setting the other parameters. Further- more, a numeric solution can be derived by giving different ranges for the parameters defining the hose 76, to come to a parameter set fulfilling the desired damping VDat a desired frequency froiioff-

[0047] Exemplary embodiments and variants of the invention are explained in more detail below with reference to the drawing, in which:

[0048] Figure 1 schematically shows a meridional section of a projection exposure ap- paratus for EUV projection lithography,

[0049] Figure 2 schematically shows a meridional section of a further projection expo- sure apparatus for DUV projection lithography,

[0050] Figure 3 shows a schematic drawing of a detail of a projection exposure appara- tus known from the state of art,

[0051] Figure 4 shows a first embodiment of the invention, and

[0052] Figure 5 a graph of a transfer function to explain the function of the invention is shown.

[0053] Figure 6 a flow chart showing an inventive method.

[0054] With reference to Figure 1 , the essential components of a microlithographic projec- tion exposure apparatus 1 are initially described below in exemplary fashion. The de- scription of the basic structure of the projection exposure apparatus 1 and its components are here not understood to be limiting.

[0055] An embodiment of an illumination system 2 of the projection exposure apparatus 1 has, in addition to a radiation source 3, an illumination optical unit 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the remaining illumination system. In this case, the illumination system does not comprise the light source 3. A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable by way of a reticle displacement drive 9, in particular in a scanning direction.

[0056] A Cartesian xyz-coordinate system is shown in Figure 1 for explanation purposes. The x-direction runs perpendicularly to the plane of the drawing into the latter. The y- direction runs horizontally and the z-direction runs vertically. The scanning direction extends along the y-direction in Figure 1 . The z-direction runs perpendicular to the object plane 6.

[0057] The projection exposure apparatus 1 comprises a projection optical unit 10. The pro- jection optical unit 10 serves for imaging 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 between the object plane 6 and the image plane 12 that differs from 0° is also possible.

[0058] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 ar- ranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable by way of a wafer displace- ment drive 15, in particular along the y-direction. The displacement on the one hand of the reticle 7 by way of the reticle displacement drive 9 and on the other hand of the wafer 13 by way of the wafer displacement drive 15 can take place in such a way as to be synchronized with one another.

[0059] 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 used radiation, illumi- nation radiation or illumination light. In particular, the used radiation has 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 GDPP 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).

[0060] The illumination radiation 16 emerging from the radiation source 3 is focused by a collector 17. The collector 17 may be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The illumination radiation 16 may be incident on the at least one reflection surface of the collector 17 with grazing incidence (Gl), that is to say at angles of incidence of greater than 45°, or with normal incidence (N I), i.e. at angles of incidence of less than 45°. The collector 17 can be structured and / or coated, firstly, for optimizing its reflectivity for the used radiation and, secondly, for suppressing extraneous light.

[0061] Downstream of the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 may represent a separation between a radiation source module, having the radiation source 3 and the collector 17, and the illumination optical unit 4.

[0062] The illumination optical unit 4 comprises a deflection mirror 19 and, arranged down- stream thereof in the beam path, a first facet mirror 20. The deflection mirror 19 may be a plane deflection mirror or, alternatively, a mirror with a beam-influencing effect that goes beyond the purely deflecting effect. As an alternative or in addition thereto, the deflection mirror 19 can be embodied as a spectral filter separating a used light wavelength of the illumination radiation 16 from extraneous light having a wavelength that deviates therefrom. If the first facet mirror 20 is arranged in a plane of the illumi- nation optical unit 4 that is optically conjugate to the object plane 6 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a multi- plicity of individual first facets 21 , which are also referred to below as field facets. Some of these facets 21 are shown in Figure 1 only by way of example.

[0063] The first facets 21 may be embodied as macroscopic facets, in particular as rectan- gular facets or as facets with an arcuate peripheral contour or a peripheral contour of part of a circle. The first facets 21 may be embodied as plane facets or alternatively as convexly or concavely curved facets.

[0064] As known for example from DE 102008 009 600 A1 , the first facets 21 themselves may also be composed in each case of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 20 may in particular be formed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1. Between the collector 17 and the deflection mirror 19, the illumination radiation 16 travels horizontally, that is to say along the y-direction.

[0065] In the beam path of the illumination optical unit 4, a second facet mirror 22 is ar- ranged downstream of the first facet mirror 20. If the second facet mirror 22 is ar- ranged in a pupil plane of the illumination optical unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 may also be arranged at a distance from a pupil plane of the illumination optical unit 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflec- tor. Specular reflectors are known from US 2006 / 0132747 A1 , EP 1 614 008 B1 and US 6,573,978.

[0066] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0067] The second facets 23 can likewise be macroscopic facets, which can, for example, have a round, rectangular or hexagonal boundary, or alternatively be facets com- posed of micromirrors. In this regard, reference is likewise made to DE 10 2008 009 600 A1 .

[0068] The second facets 23 may have planar or alternatively convexly or concavely curved reflection surfaces.

[0069] The illumination optical unit 4 consequently forms a twice-faceted system. This basic principle is also referred to as a honeycomb condenser (fly's eye integrator).

[0070] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugate to a pupil plane of the projection optical unit 10. In particu- lar, the pupil facet mirror 22 can be arranged so as to be tilted relative to a pupil plane of the projection optical unit 7, as is described, for example, in DE 10 2017 220 586 A1 .

[0071] The individual first facets 21 are imaged into the object field 5 with the aid of the sec- ond facet mirror 22. The second facet mirror 22 is the last beam-shaping mirror or else, in fact, the last mirror for the illumination radiation 16 in the beam path before the object field 5. In a further embodiment of the illumination optical unit 4 that is not shown, a trans- mission optical unit contributing in particular to the imaging of the first facets 21 into the object field 5 may be arranged in the beam path between the second facet mirror 22 and the object field 5. The transmission optical unit may have exactly one mirror or else alternatively two or more mirrors, which are arranged one behind the other in the beam path of the illumination optical unit 4. The transmission optical unit may in particular comprise one or two normal-incidence mirrors (Nl mirrors) and / or one or two grazing-incidence mirrors (Gl mirrors).

[0072] In the embodiment shown in Figure 1 , the illumination optical unit 4 has exactly three mirrors downstream of the collector 17, specifically the deflection mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

[0073] The deflection mirror 19 can also be dispensed with in a further embodiment of the il- lumination optical unit 4, and so the illumination optical unit 4 can then have exactly two mirrors downstream of the collector 17, specifically the first facet mirror 20 and the second facet mirror 22.

[0074] As a rule, the imaging of the first facets 21 into the object plane 6 by means of the second facets 23 or using the second facets 23 and a transmission optical unit is only approximate imaging.

[0075] The projection optical unit 10 comprises a plurality of mirrors Mi, which are consecu- tively numbered in accordance with their arrangement in the beam path of the projec- tion exposure apparatus 1 .

[0076] In the example illustrated in Figure 1 , the projection optical unit 10 comprises six mir- rors M1 to M6. Alternatives with four, eight, ten, twelve or any other number of mir- rors Mi are similarly possible. The penultimate mirror M5 and the last mirror M6 each have a through opening for the illumination radiation 16. The projection optical unit 10 is a double-obscured optical unit. The projection optical unit 10 has an image-side numerical aperture which is greater than 0.3 and which can also be greater than 0.6 and can, for example, be 0.7 or 0.75. Reflection surfaces of the mirrors Mi can be embodied as free-form surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi may be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface form. Just like the mirrors of the illumination optical unit 4, the mirrors Mi may have highly reflective coatings for the illumination radiation 16. These coatings may be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0077] The projection optical unit 10 has a large object image offset in the y-direction be- tween a y-coordinate of a centre of the object field 5 and a y-coordinate of the centre of the image field 11 . In the y-direction, this object-image offset can be approximately the same size as a z-distance between the object plane 6 and the image plane 12.

[0078] In particular, the projection optical unit 10 may have an anamorphic form. In particu- lar, it has different imaging scales px, py in the x- and y-directions. The two imaging scales px, py of the projection optical unit 10 preferably lie at (px, py) = (+ / - 0.25, / +- 0.125). A positive imaging scale p means imaging without an image reversal. A nega- tive sign for the imaging scale p means imaging with an image reversal.

[0079] The projection optical unit 10 consequently leads to a reduction in size with a ratio of 4:1 in the x-direction, that is to say in a direction perpendicular to the scanning direc- tion.

[0080] The projection optical unit 10 leads to a reduction in size of 8:1 in the y-direction, that is to say in the scanning direction.

[0081] Other imaging scales are similarly possible. Imaging scales with the same sign and the same absolute value in the x-direction and y-direction are also possible, for ex- ample with absolute values of 0.125 or of 0.25.

[0082] The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field 5 and the image field 11 may be the same or, depending on the embodiment of the projection optical unit 10, may differ. Examples of projection optical units with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1 . In each case one of the pupil facets 23 is assigned to exactly one of the field facets 21 for forming in each case an illumination channel for illuminating the object field 5. In particular, this can yield illumination according to the Kohler principle. The far field is decomposed into a multiplicity of object fields 5 with the aid of the field facets 21 . The field facets 21 produce a plurality of images of the intermediate focus on the pupil facets 23 respectively assigned thereto.

[0083] The field facets 21 are imaged, in each case by way of an assigned pupil facet 23, onto the reticle 7 in a manner such that they are superposed on one another for the purposes of illuminating 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%. The field uniformity can be achieved by way of the superposition of different illumination channels.

[0084] The illumination of the entrance pupil of the projection optical unit 10 can be defined geometrically by way of an arrangement of the pupil facets. The intensity distribution in the entrance pupil of the projection optical unit 10 can be set by selecting the illu- mination channels, in particular the subset of the pupil facets which guide light. This intensity distribution is also referred to as illumination setting.

[0085] A likewise preferred pupil uniformity in the region of defined illuminated sections of an illumination pupil of the illumination optical unit 4 can be achieved by a redistribution of the illumination channels.

[0086] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optical unit 10 are described below.

[0087] In particular, the projection optical unit 10 may have a homocentric entrance pupil. The latter may be accessible. It may also be inaccessible.

[0088] The entrance pupil of the projection optical unit 10 cannot be exactly illuminated us- ing the pupil facet mirror 22 on a regular basis. In the case of imaging the projection optical unit 10 in which the centre of the pupil facet mirror 22 is telecentrically imaged onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find an area in which the distance of the aperture rays determined in pairs becomes minimal. This area represents the entrance pupil or an area in real space that is conjugate thereto. In particular, this area has a finite curvature.

[0089] It may be that the projection optical unit 10 has different positions of the entrance pupil for the tangential beam path and for the sagittal beam path. In this case, an imaging element, in particular an optical component part of the transmission optical unit, should be provided between the second facet mirror 22 and the reticle 7. With the aid of this optical element, the different position of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0090] In the arrangement of the components of the illumination optical unit 4 illustrated in Figure 1 , the pupil facet mirror 22 is arranged in an area conjugate to the entrance pupil of the projection optical unit 10. The field facet mirror 20 is arranged in tilted fashion with respect to the object plane 6. The first facet mirror 20 is arranged in tilted fashion with respect to an arrangement plane defined by the deflection mirror 19.

[0091] The first facet mirror 20 is arranged so as to be tilted in relation to an arrangement plane defined by the second facet mirror 22.

[0092] Figure 2 schematically shows, in a meridional section, a further projection exposure apparatus 101 for DUV projection lithography, in which the invention can likewise be used.

[0093] The construction of the projection exposure apparatus 101 and the principle of the imaging are comparable with the construction and procedure described in Figure 1 . Identical component parts are designated by a reference sign increased by 100 rela- tive to Figure 1 , i.e. the reference signs in Figure 2 begin with 101.

[0094] In contrast to an EUV projection exposure apparatus 1 as described in Figure 1 , re- fractive, diffractive and / or reflective optical elements 117, such as for example lens elements, mirrors, prisms, terminating plates, and the like, can be used for imaging or for illumination in the DUV projection exposure apparatus 101 on account of the greater wavelength of the DUV radiation 116, used as used light, in the range from 100 nm to 300 nm, in particular of 193 nm. The projection exposure apparatus 101 in this case substantially comprises an illumination system 102, a reticle holder 108 for receiving and exactly positioning a reticle 107 provided with a structure, by which the later structures on a wafer 113 are determined, a wafer holder 114 for holding, mov- ing and exactly positioning said wafer 113 and a projection optical unit 110, with a plurality of optical elements 117, which are held by way of mounts 118 in a lens hous- ing 119 of the projection optical unit 110.

[0095] The illumination system 102 provides DUV radiation 116, which is required for the imaging of the reticle 107 on the wafer 113. A laser, a plasma source or the like can be used as the source of this radiation 116. The radiation 116 is shaped in the illumi- nation system 102 by means of optical elements such that the DUV radiation 116 has the desired properties with regard to diameter, polarization, shape of the wave front and the like when it is incident on the reticle 107.

[0096] Apart from the additional use of refractive optical elements 117, such as lens ele- ments, prisms, terminating plates, the construction of the downstream projection opti- cal unit 110 with the lens housing 119 does not differ in principle from the construction described in Figure 1 and is therefore not described in further detail.

[0097] Figure 3 shows a schematic drawing of a projection optical unit 10 of a projection ex- posure apparatus 1 known from the state of the art, as explained in detail in figure 1 . The projection optical unit 10 shown in figure 3 is placed on a machine base of the projection exposure apparatus 1 and comprises a base frame 31 , which is decoupled from the machine base 30 by a decoupling 49 to avoid transmitted mechanical vibra- tions from the machine base 30 to the base frame 31 . In the following, all mentioned decoupling 49 without a special meaning for the invention are designated with the reference number 49 for simplification, whereas relevant decouplings are each given a separate reference number.

[0098] The base frame 31 is connected to an intermediate frame 32 via another decoupling 49, whereas the intermediate frame 32 itself holds a module frame 33 and a refer- ence frame 34 via further decouplings 49. The module frame 33 holds several mirror modules 35.1 , 35.2, 35.3, 35.4, 35.5, 35.6, while the reference frame 34 holds sen- sors 38 to capture the position of the mirror modules 35.1 , 35.2, 35.3, 35.4, 35.5, 35.6 in reference to the reference frame 34. The decouplings 49 minimize the transmission of mechanical vibrations from the ma- chine base 30 to the mirrors of the mirror modules 35.1 , 35.2, 35.3, 35.4, 35.5, 35.6, whereas the mirrors are not specifically labeled with an individual reference number in figure 3. It is well known to an expert in the field of decoupling of mechanical vibra- tions, that the shown decouplings 49 are not identical as the identical reference num- ber might suggest, but are each designed to meet the individual requirements set on them. The mirror modules 35.1 , 35.2, 35.3, 35.4, 35.5, 35.6 are connected to the module frame 33 via connecting elements 36. The mirror modules 35.1 , 35.2, 35.3, 35.4, 35.5, 35.6 additionally comprise sensors 38, which capture the position of the mirrors with respect to the reference frame 34, whereby the position of each mirror to one another and against further components of the projection exposure apparatus 1 , as for example the reticle 7 and the wafer 13, can be controlled by a control unit (not shown). In figure 3, the mirror module 35.3 is exemplarily connected to a control unit 46 via a line 47. The line 47 features a decoupling loop 44 between the base frame 31 and the intermediate frame 32, between the intermediate frame 32 and the mod- ule frame 33 as well as between the module frame 33 and the mirror module 35.3 to minimize the transmission of mechanical vibrations from the base frame 31 towards the mirror.

[0099] The mirror module 35.3 features exemplary fluid line 39 for cooling of the mirror with a fluid 40, whereas the fluid can for example be pure water. The fluid 40 is transmit- ted via a feed line 42 from a first area 41 .1 of a water cabinet 41 to the fluid line 39 of the mirror arranged on the mirror module 35.3 and via a drainage line 43 back to a second area 41 .2 of the water cabinet 41 , whereas both areas 41 .1 , 41 .2 are con- nected with one another via a connecting line 45. The water cabinet 41 is designed for the supply and the preparation of the fluid 40 and is connected to the base frame 31 and the machine base 30 via decouplings 49. The feed line 42 and the drainage line 43 features between the base frame 31 and the intermediate frame 32, between the intermediate frame 32 and the module frame 33, as well as between the module frame 33 and the mirror (not shown) a decoupling loop 44 each, which also serve to minimize the transmission of mechanical and acoustic vibrations to the mirror mod- ules 35.1 , 35.2, 35.3, 35.4, 35.5, 35.6. For explanation the disturbance path 48 of the acoustic vibrations from the water cabinet 41 to the mirror is displayed as a dashed line in the figure 3, whereby the dotes indicate locations at which the acoustic vibra- tions can be generated via mechanical vibrations transmitted to the fluid. The feed line 42 and the drainage line 43 comprise pipe dampers 50 for damping the mechani- cal vibrations transmitted by the lines 42, 43, as well as fluid dampers 60, as for ex- ample Helmholtz-Dampers, for damping acoustic vibrations transmitted over the fluid 40. The dampers 50, 60 are placed on different points of the lines 42, 43 due to con- straints in building volume. As a result, the acoustic vibrations transmitted via the lines 42, 43 and the fluid 40 can also interact downstream of the dampers, taking a negative influence on the imaging quality.

[0100] The projection optical unit 10 is qualified for quality control as a single component of the projection exposure apparatus. Among other things, the transmission of mechani- cal vibrations via the fluid lines 39, 42, 43 and the lines 47 are qualified for their effect on the mirrors and therefore on the image quality of the projection exposure appara- tus 1 itself.

[0101] Figure 4 displays an inventive pipe section 70 which could be used in a fluid line 39, 42, 43 in figure 3. The pipe section 70 is part of a fluid channel 71 and comprises a damping section 72 with a pipe connector 73.1 , 73.2 on each side of the damping section 72. The damping section 72 is connected with the pipe connectors 73.1 , 73.2 via adapters 74.1 , 74.2 by welding, clamping or any other suitable connecting tech- nology.

[0102] The damping section 72 comprises an inner pipe in the form of a viscoelastic hose 76 with a length L, which is in the example shown in figure 4 encapsulated within an outer pipe in the form of a corrugated tube 75. The fluid 79 of the fluid channel 71 flows within the viscoelastic hose 76 and the adapters 74.1 , 74.2 ensure that no fluid will neither leak into the gas volume 77 between the viscoelastic hose 76 and the cor- rugated tube 75 nor to the surrounding of the damping section 72.

[0103] Due to its structure, the damping section 72 contributes, to a certain extent, to toler- ance compensation between different parts of the assembly, as well as to interfaces of a fluid line system, the assembly will be connected to. There are two basic principles of dampening mechanical vibrations transmitted by the fluid 79 by the viscoelastic hose 76, which will be explained in detail below. Both prin- ciples are based on the viscoelastic properties of the viscoelastic hose 76, which, e. g., comprises one or more of butyl rubber (HR), chlorosulfonated polyethylene (CSM), epichlorohydrin rubber (ECO), polynorbonene rubber (PNR), ethylene-vinyl acetate rubber (EVA), acrylate rubber (ACM), ethylene propylene diene monomer (EPDM) and silicon. These materials have a Young's modulus in the range of 0.1 -1000 MPa, preferably in a range of 0.1-400 MPa and particularly preferred in a range of 0.1 -50 MPa.

[0104] Furthermore, the materials of the inner pipe possess viscoelastic properties, which for example result in a frequency dependent and complex elasticity modulus (Young's modulus), whereas the real part E’ of the complex Young's modulus stands for storage of energy and the imaginary part E” of the complex Young's modulus stands for a loss of energy by dissipation. The ratio of E" / E' describes the loss factor q of the material, which defines the effectiveness of the damping of acoustic vibra- tions within the fluid.

[0105] The first principle is based on the viscoelastic properties and dissipates energy of the acoustic vibrations according to the loss factor q mentioned above.

[0106] The second principle, the so-called roll-off effect, occurs due to the viscoelastic damping within the wall of the hose 76. Depending on the geometry of the viscoelas- tic hose 76, particularly the length L and wall thickness t of the viscoelastic hose 76 hose and the properties of the material, particularly the Young's modulus E’, E”, which will be complex for viscoelastic materials, a desired roll-off frequency froiioff can be targeted. Depending on the geometry of the viscoelastic hose 76, particularly the length L and wall thickness t of the viscoelastic hose 76 and the properties of the ma- terial, particularly the Young's modulus, which will be complex for viscoelastic materi- als, a cut-off frequency can be designed. The cut-off frequency is the frequency at which destructive interference will become beneficial, based on a phase lag between the oncoming acoustic waves and the acoustic wave generated by the viscoelastic hose 76. When the phase lag reaches 180°, the acoustic vibration for this frequency will be zero. In order to use the full damping potential of the damping section of the pipe it is nec- essary that the viscoelastic hose 76 can move and expand freely within the corru- gated tube 75, in radial direction. Besides the room enabling the hose 76 to move and expand, particularly in radial direction, the stiffness of the volume surrounding the hose 76 should be as small as possible, for example a factor of 5 - 5000 smaller than the stiffness of the viscoelastic hose 76, preferably a factor of 5 - 500 smaller than the stiffness of the viscoelastic hose 76, particularly preferred a factor of 5 - 100 smaller than the stiffness of the viscoelastic hose 76. The pressure ratio between the inside and the outside of the viscoelastic hose 76 therefore can be in a range of 0.1 - 1000, preferably in a range of 0.5 - 500, particularly preferred in a range of 0.5 - 20.

[0107] The pressure within the viscoelastic hose 76 can be in a range of 0 - 20 bar, prefer- ably in a range of 0 - 10 bar and particularly preferred in a range of 0 - 7 bar. The pressure in the volume surrounding the viscoelastic hose 76 can be in a range of 0 - 20 bar, preferably in a range of 0 - 10 bar and particularly preferred in a range of 0 - 7 bar.

[0108] Figure 5 shows a diagram with three transfer functions 80.1 , 80.2, 80.3 of the pres- sure after and before the pipe section 70 of a fluid line 39, 42, 43 as shown in figure 4, whereas the three transfer functions 80.1 , 80.2, 80.3 are based on different materi- als of the viscoelastic hose 76 (figure 4). All transfer functions 80.1 , 80.2, 80.3 neither damp (amplification below 1 ) nor amplify (amplification above 1 ) significantly the acoustic vibrations in the lower frequency range. Transfer function 80.3 displayed as a dashed line in figure 5 follows a more or less constant amplification of approxi- mately 1 over the rest of exemplary shown frequency range, which corresponds to the behavior of a comparatively stiff material and / or material with a low loss factor, in other words a material with a high stiffness to loss factor ratio. Transfer function 80.2 displayed as a dash-dotted line in figure 5 also follows a more or less constant ampli- fication of approximately 1 first, but then the amplification reduces below 1 , which corresponds to a damping of the acoustic vibrations within the fluid with increasing frequency towards the end of exemplary shown frequency range. This behavior cor- responds to a medium stiff material and / or material with a medium loss factor, which can be summarized by a material with a medium stiffness to loss factor ratio. Finally the transfer function 80.1 , corresponding to a low stiffness material and / or material with a high loss factor, in other words a material with a low stiffness to loss factor ra- tio and displayed in a solid line in figure 5, shows a reduction of the amplification and therefore an increased damping starting well before the transfer function 80.2 of the medium stiff material and / or material with a medium loss factor, in other words a ma- terial with a medium stiffness to loss factor ratio. The damping effect (= decreasing amplification below 1 ) is based on the roll-off effect 81 , described in figure 4 (figure 4). The roll-off effect 81 can also be seen as a filter for a defined frequency range, in the example shown in figure 5 as a low pass filter. The shown frequency range dis- played in figure 5 can be in a range of 0 - 3000 Hz, preferably in a range of 0 - 1000 Hz, particularly preferred in a range of 0 - 500 Hz. Nevertheless, the effect may change for higher or lower frequencies due to other effects as inertia.

[0109] The idea of using a viscoelastic hose 76 for damping acoustic vibrations within a pipe section 70 of a fluid line 39, 42, 43 of a semiconductor apparatus in itself can be re- garded an invention, particularly also without the additional aspect of a surrounding second pipe and independent of the properties of the second pipe as for example, if it is corrugated and / or stiff and / or flexible.

[0110] Figure 6 shows a possible method for designing pipe in the form of a hose 76 for an assembly 70 for a fluid line 39,42,43 for a semiconductor apparatus 1 ,101 comprising at least one damping section 72 to damp acoustic vibrations within a fluid 79, the damping section 72 comprising the hose 76 comprising a viscoelastic material.

[0111] In a first step 91 a desired transfer factor VDand a desired roll-off frequency froiioff for a given fluid is determined.

[0112] In a second step 92 a material frequency fmateriai based on the roll-off frequency fronOff and the transfer factor VDis determined.

[0113] In a third step 93 the parameters of the hose 76 are determined in such a way that the following equation applies:

[0114] In particular, after choosing the damping factor a correlation between the frequency of the acoustic vibration and the desired roll-off frequency can be and the one can choose a most likely corresponding material defining the frequency dependent and complex Young’s Modulus E’, E” and thereby the loss factor q, which also will be de- pendent on the frequency of the acoustic vibrations.

[0115] List of Reference Signs

[0116] 1 Projection exposure apparatus

[0117] 2 Illumination system

[0118] 3 Radiation source

[0119] 4 Illumination optical unit

[0120] 5 Object field

[0121] 6 Object plane

[0122] 7 Reticle

[0123] 8 Reticle holder

[0124] 9 Reticle displacement drive

[0125] 10 Projection optical unit

[0126] 11 Image field

[0127] 12 Image plane

[0128] 13 Wafers

[0129] 14 Wafer holder

[0130] 15 Wafer displacement drive

[0131] 16 EUV radiation

[0132] 17 Collector

[0133] 18 Intermediate focal plane

[0134] 19 Deflection mirror

[0135] 20 Facet mirror

[0136] 21 Facets

[0137] 22 Facet mirror

[0138] 23 Facets

[0139] 30 Machine base

[0140] 31 Base frame

[0141] 32 Intermediate frame

[0142] 33 Module frame

[0143] 34 Reference frame

[0144] 35.1 - 35.6 Mirror module Connecting element

[0145] Sensor

[0146] Fluid line

[0147] Fluid ,41.1 , 1.2 Water cabinet

[0148] Feed line

[0149] Drainage line

[0150] Decoupling loop

[0151] Connecting pipe

[0152] Control unit

[0153] Line

[0154] Mechanical / Acoustic vibration disturbance path

[0155] General decoupling

[0156] Pipe damper

[0157] Fluid damper

[0158] Pipe section

[0159] Fluid channel

[0160] Damping section .1 ,73.2 Pipe connector .1 ,74.2 Pipe adapter

[0161] Corrugated tube

[0162] Viscoelastic hose

[0163] Gas volume

[0164] Outer Pipe

[0165] Fluid .1-80.3 Transfer function

[0166] Roll-off effect

[0167] Step 1 of method

[0168] Step 2 of method

[0169] Step 3 of method 1 Projection exposure apparatus 102 Illumination system

[0170] 107 Reticle

[0171] 108 Reticle holder

[0172] 110 Projection optical unit

[0173] 113 Wafer

[0174] 114 Wafer holder

[0175] 116 DUV radiation

[0176] 117 Optical element

[0177] 118 Optical element mount

[0178] 119 Lens housing

[0179] M1-M6 Mirror

Claims

Patent Claims1 . Assembly (70) for a fluid line (39,42,43) for a semiconductor apparatus (1 ,101 ) comprising at least one damping section (72) to damp acoustic vibrations within a fluid (79), the damping section (72) comprising a pipe (76) comprising a viscoelastic material characterized in that, the pipe comprising when filled with the fluid (79) a transfer factor (VD) smaller than 0.95, preferably smaller than 0.8, particularly preferred smaller than 0,4 at a roll-off frequency in the range of 0-3000 Hz, preferably in a range of 0-1000 Hz, particularly preferred in a range of 0-500 Hz.

2. Assembly (70) according to claim 1 , characterized in that, the material and geometric parameters of the pipe (76) are chosen at a de- sired roll-off frequency (froiioff) and a desired transfer factor (VD), when filled with the fluid (79), in a way, that the following equation applies:E” ( / material)T](0 = E' f material) whereby f rolloff = Rolloff frequencyL = Length of the viscoelastic pipe3. Assembly (70) according to claim 2, characterized in that,Young's modulus E’ of the viscoelastic material is in a range of 0.1-1000 MPa[0-3000 Hz], preferably in a range of 0.1-400 MPa [0-3000 Hz] and particularly preferably in a range of 0.1-50 MPa [0-3000 Hz],4. Assembly (70) according to claims 2 or 3, characterized in that, the loss factor q of the viscoelastic material is in a range of 0.1-3 [0-3000 Hz], preferably in a range of 0.5-2 [0-3000 Hz], particularly preferred in a range of1-2 [0-3000 Hz],5. Assembly (70) according to one of the preceding claims, characterized in that, the inner diameter Di of the pipe (76) is in a range of 1-40 mm, preferably in a range of 2-25 mm, particularly preferred in a rage of 4-15 mm.

6. Assembly (70) according to one of the preceding claims, characterized in that, the wall thickness t of the pipe (76) is in the range of 0.2-20 mm, preferably in the range of 0.2-15 mm, particularly preferred in the range of 0.5-10 mm.

7. Assembly (70) according to one of the preceding claims, characterized in that, the length L [mm] of the pipe (76) is in the range of 10-2000 mm, preferably inthe range of 10-1000 mm and particularly preferred in the range of 20-500 mm.

8. Assembly (70) according to one of the preceding claims, characterized in that,. the damping section (72) comprises an outer pipe (75,78).

9. Assembly (70) according to claim 8, characterized in that, the inner pipe (76) and the outer pipe (75,78) are at both ends connected to pipe connectors (73.1 ,73.2) of the assembly (70) via pipe adapters (74.1 ,74.2).

10. Assembly (70) according to claims 8 or 9, characterized in that, a volume (77) between the inner pipe (76) and the inner pipe (76) enclosing outer pipe (75) is closed.

11. Assembly (70) according to claiml 0, characterized in that, the closed volume (77) comprises a compressible fluid.

12. Assembly (70) according to claim 10 or 11 , characterized in that, the closed volume (77) comprises air, nitrogen or helium.

13. Assembly (70) according to one of the preceding claims, characterized in that, the stiffness of a volume (77) surrounding the pipe (76) is a factor of ca. 5- 5000 smaller than the stiffness of the pipe (76), preferably a factor of 5-500 smaller than the stiffness of the pipe (76), particularly preferred a factor of 5- 100 smaller than the stiffness of the pipe (76).

14. Assembly (70) according to one of claims 8 to 13, characterized in that, the outer pipe (75,78) can be flexible and / or stiff.

15. Assembly (70) according to one of claims 8 to 14, characterized in that, the distance between the inner pipe (76) and the outer pipe (75,78) is de- signed in such a way, that the outer pipe (75,78) prevents the inner pipe (75,78) from expanding over a predefined volume.

16. Assembly (70) according one of the preceding claims, characterized in that, the fluid (79) comprises water.

17. Assembly (70) according one of the preceding claims, characterized in that, the pipe (76) comprises one or more of the following materials: Butyl rubber (HR), chlorosulfonated polyethylene (CSM), epichlorohydrin rubber (ECO), polynorbonene rubber (PNR), ethylene-vinyl acetate rubber (EVA), acrylate rubber (ACM), ethylene propylene diene monomer (EPDM) and silicon.

18. Semiconductor apparatus (1 ,101 ), preferably a projections exposure appara- tus (1 ,101 ), particularly preferred a EUV projection exposure apparatus (1 ), comprising at least one assembly (70) according to one of the preceding claims.

19. Method for designing a pipe (76) for an assembly (70) for a fluid line (39,42,43) for a semiconductor apparatus (1 ,101 ) comprising at least one damping section (72) to damp acoustic vibrations within a fluid (79), the damp- ing section (72) comprising the pipe (76) comprising a viscoelastic material the method comprising the following steps:- Determining a desired transfer factor VDand a desired roll-off frequency froiioff for a given fluid,- Determining a material frequency fmateriai based on the roll-off frequency froiioff and the transfer factor VD,- Determining the material and geometric parameters of the pipe (76) in such a way that the following equation applies:

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