Chiller for cooling position-sensitive components of a lithography system

Abstract

A cooling device (200) for cooling a position-sensitive component (102) of a lithography system (1), comprising: a cooling line (206) having a liquid chamber (218) for transporting a cooling liquid (112) to the position-sensitive component (102) and a gas chamber (220) for containing a gas (222); and an elastic separation membrane (224) disposed in the cooling line (206) and serving to separate the gas chamber (220) from the liquid chamber (218).

Description

[Technical Field]

[0001] The present invention relates to a cooling device for cooling position-sensitive components of a lithographic apparatus, a corresponding lithographic apparatus, and a method for operating a cooling device of a lithographic apparatus.

[0002] The contents of priority application No. 10 2022 125 354.6 are incorporated by reference in their entirety. [Background technology]

[0003] Microlithography is used in the manufacture of finely structured components, such as integrated circuits. The microlithography process is carried out using a lithography apparatus that includes an illumination system and a projection system. The image of a mask (reticle), illuminated by the illumination system, is projected by the projection system onto a substrate, such as a silicon wafer, that is coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system, thereby transferring the mask structure into the photosensitive coating on the substrate.

[0004] The desire for further miniaturization of structures in integrated circuit manufacturing has led to the development of EUV lithography systems that use light with wavelengths in the 0.1 mm to 30 mm range, particularly 13.5 mm. Because most materials absorb light at this wavelength, such EUV lithography systems must use reflective optical elements, i.e., mirrors, instead of the conventional refractive optical units, i.e., lens elements.

[0005] The demands on the accuracy and precision of the imaging properties of lithographic apparatuses are constantly increasing. From a dynamic point of view, in this context the influence of disturbance inputs on the movements of various position-sensitive components of the lithographic apparatus must be minimized. For example, very precise positioning of optical components of the lithographic apparatus, in particular mirrors, is required. Dynamic disturbance excitation of optical components can be caused, for example, by movements of other components of the lithographic apparatus or by acoustic disturbances. Acoustic disturbances are transmitted to the position-sensitive components of the lithographic apparatus, for example, as pressure fluctuations of a coolant in a cooling line of a cooling device of the lithographic apparatus.

[0006] As lithographic apparatus become more complex, it is expected that there will be more dynamic disturbance excitations both inside and outside the system, and therefore more mechanisms for suppressing or compensating for said disturbance excitations are desirable and necessary. Summary of the Invention [Problem to be solved by the invention]

[0007] Against this background, the problem solved by the present invention is to provide an improved cooling device for a lithographic apparatus, a corresponding lithographic apparatus, and a method for operating a cooling device for a lithographic apparatus. [Means for solving the problem]

[0008] According to a first aspect, a cooling device for cooling a position sensitive component of a lithographic apparatus is proposed, the cooling device comprising: a cooling line having a liquid space for transporting a cooling liquid to the position sensitive component and a gas space for containing a gas; an elastic separation membrane disposed within the cooling line and serving to separate the gas space from the liquid space; Equipped with.

[0009] By introducing a compressible gas volume into the cooling line, pressure fluctuations in the cooling liquid can be damped, thereby reducing their propagation through the cooling liquid. In particular, the elastic separator membrane is configured to deform and thereby change the volume of the liquid space at the expense of the volume of the gas space.

[0010] For example, when viewed from the cross section of the cooling line, as the pressure of the cooling liquid increases, the separation membrane deforms toward the original gas space, so the volume of the liquid space increases and the volume of the gas space decreases accordingly. Therefore, the increase in the pressure of the cooling liquid can be suppressed by the expansion of the liquid in the liquid space and the compression of the gas in the gas space.

[0011] The same thing happens when the pressure of the coolant in the cooling space of the cooling line drops, causing the volume of the gas space to increase, which causes the gas in the gas space to expand and the coolant in the liquid space to compress, reducing the pressure drop of the coolant.

[0012] Thus, the compressible gas volume can also be used to dampen cyclic pressure fluctuations in the coolant.

[0013] A position-sensitive component of a lithographic apparatus may be an optical or mechanical component of the lithographic apparatus, for example a projection optical unit of the lithographic apparatus. In particular, a position-sensitive component is a component that must be kept in a precise position with very small tolerances during operation of the lithographic apparatus.

[0014] Position-sensitive components of a lithographic apparatus are, for example, mirrors of the lithographic apparatus, for example mirrors of a projection optical unit of the lithographic apparatus. The mirrors of the projection optical unit of an EUV lithographic apparatus are typically movably mounted in a force frame by means of actuators so that the position of each mirror can be precisely adapted.

[0015] The position-sensitive component of the lithographic apparatus can also be a frame structure that serves as a (e.g., optical) reference. The position-sensitive component can, for example, be a sensor frame of the lithographic apparatus, for example of a projection optical unit of the lithographic apparatus. The sensor frame typically includes a sensor device that measures the current position of one or more optical components of the lithographic apparatus relative to the sensor frame. The sensor frame is, for example, mounted so as to be vibrationally decoupled from the force frame of the optical component(s). The sensor device includes, for example, one or more sensors, such as interferometers and / or other measurement devices, that capture the position of the optical component(s). The optical component(s) can, for example, include a reflective element that reflects light (e.g., laser light) transmitted by the sensor. For example, the one or more sensors serve to capture the position of the optical component(s) in six degrees of freedom. The six degrees of freedom include, in particular, three translational degrees of freedom (eg, in three mutually perpendicular spatial directions) and three rotational degrees of freedom (relating to rotations about three mutually perpendicular spatial directions).

[0016] The proposed cooling device with a compressible gas volume integrated in the cooling line allows pressure fluctuations in the cooling liquid to be damped and reduced or prevented from being transmitted to the position-sensitive component. As a result, the accuracy of the position of the position-sensitive component and thus of the optical or reference characteristics can be increased. As a result, the imaging properties of the lithographic apparatus can be improved. Furthermore, disturbance excitations can be better compensated for, even in increasingly complex lithographic apparatuses with an increasing number of disturbance sources.

[0017] For example, the lithography apparatus may be an EUV or DUV lithography apparatus. EUV stands for "extreme ultraviolet" and refers to an operating light wavelength of 0.1 nm to 30 nm, particularly 13.5 nm. Furthermore, DUV stands for "deep ultraviolet" and refers to an operating light wavelength of 30 nm to 250 nm.

[0018] An EUV or DUV lithography apparatus comprises an illumination system and a projection system, and is used in particular to project an image of a mask (reticle) illuminated by the illumination system onto a substrate, e.g., a silicon wafer, that is coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system, thereby transferring the mask structure into the photosensitive coating on the substrate.

[0019] For example, a cooling line is a conduit through which a cooling liquid passes. For example, a cooling line includes a metal pipe and / or a stainless steel pipe. For example, a cooling line may have a circular cross section. The cooling liquid may be, or contain, water, for example. For example, a cooling line serves to transport a cooling liquid to and / or from a position-sensitive component. For example, a cooling line serves to transport (return) a cooling liquid from a cooling unit of a cooling device to the position-sensitive component and / or from the position-sensitive component to the cooling unit. A cooling device may include two or more cooling lines.

[0020] In particular, the cooling device serves to protect the position sensitive components from high temperatures and temperature fluctuations.

[0021] In particular, mirrors (as an example of position-sensitive components) in EUV lithography apparatuses heat up as a result of absorbing high-energy EUV radiation. The resulting high temperatures and temperature fluctuations of the mirrors, and the resulting thermal deformation of the mirrors, lead to wavefront aberrations and thus adversely affect the imaging properties of the mirrors. Mirrors in lithography apparatuses can be actively cooled to prevent thermally induced deformations.

[0022] The cooling device may (additionally or instead) also serve to cool, for example, the sensor frame (as an example of a position-sensitive component). This may prevent the sensor frame from heating up due to thermal radiation. Thermal radiation is caused, in particular, by operating light of the lithography apparatus absorbed by the mirror surface or structural elements. For example, actuators and heater heads may be further heat sources. The cooling device may help to create a stable temperature environment for the sensor frame. As a result, position measurements of one or more mirrors using a sensor device held by the sensor frame may be performed with greater accuracy.

[0023] The cooling system further comprises, for example, a cooling unit for cooling the cooling liquid, one or more pumps for generating a required refrigerant flow rate of the cooling liquid, and one or more valves for controlling the cooling flow.

[0024] A specific coolant flow rate is required for cooling and is achieved by a pump system. This dynamic disturbance is excited because each pump generates local pressure fluctuations. These are transmitted throughout the cooling circuit via coolant noise (waterborne noise, longitudinal waterborne acoustic waves). Furthermore, cross-sectional changes and bends in the liquid lines, as well as built-in valves in the cooling circuit, can all be sources of disturbances that cause local pressure fluctuations in the liquid. This type of dynamic disturbance excitation is also called flow-induced vibration (FIV). Waterborne noise transmits disturbance excitation to cooled position-sensitive components, causing the position of the position-sensitive components to deviate from their target position. In particular, pressure surges in the coolant act on the surfaces of the cooled position-sensitive components. The pressure surges are converted into forces at the affected surfaces. These forces lead to the position-sensitive components deviating from their target position. The liquid space of the cooling line is located inside the cooling line and serves to flow the coolant there. Furthermore, the gas space is located inside the cooling line and serves to contain the gas. The volumes of the liquid space and the gas space are variable due to an elastic separating membrane that separates the liquid space from the gas space, and as a result the volume of the cooling liquid and the volume of the gas are variable due to the elastic separating membrane.

[0025] During operation of the cooling device, e.g. during operation of the lithographic apparatus, the liquid space, when viewed in cross section of the cooling line, is e.g. completely filled with cooling liquid, and the gas space, when viewed in cross section of the cooling line, is e.g. completely filled with gas.

[0026] The elastic separator membrane is particularly configured to form a gas bubble with the gas contained in the gas space, for example an axial gas bubble relative to a central longitudinal axis of the liquid line.

[0027] The elastic separating membrane is in particular (reversibly) deformable in order to adapt the volume of the liquid space, and therefore the volume of the cooling liquid, to the pressure of the cooling liquid in the liquid space.

[0028] For example, the elastic separator membrane is liquid-tight and / or gas-tight.

[0029] For example, the elastic separation membrane may comprise a (e.g., thin) elastic material. The elastic separation membrane material may contain, for example, polyurethane, silicone, unvulcanized rubber, vulcanized rubber, natural rubber, silicone rubber, fluororubber, and / or another elastic material. Due to its aging resistance and low outgassing properties, fluororubber is particularly suitable for use in vacuums. The elastic separation membrane material may also contain, for example, a fluorothermoplastic resin such as tetrafluoroethylene, hexafluoropropylene, and / or vinylidene fluoride.

[0030] As a result of the elastic material (eg, a highly damping polymer), in addition to the compression of the separated gas volume, further damping of the pressure fluctuations of the coolant may be achieved.

[0031] The gas space may be a closed gas space containing gas in a static state, or alternatively, the gas space may be part of a gas circuit through which gas flows during operation, for example, in this case the gas flow may be achieved by means of a gas pump.

[0032] For example, the gas may be air, high purity room air, helium, and / or a gas containing one or more noble gases.

[0033] In embodiments, the cooling device includes a gas contained in a gas space, for example, the gas space in these embodiments is a sealed gas space within which the gas remains (e.g., permanently).

[0034] In embodiments, the cooling line with the integrated gas volume is configured to dampen and / or suppress pressure fluctuations of the cooling liquid in the frequency ranges of 1 Hz to 2 kHz, 1 Hz to 1 kHz, 1 Hz to 800 Hz, 1 Hz to 500 Hz, 1 Hz to 400 Hz, 1 Hz to 200 Hz, 1 Hz to 100 Hz, and / or 50 Hz to 150 Hz. 。

[0035] According to one embodiment, the elastic separation membrane is a pressure membrane configured to deform when the pressure of the coolant changes so that the volume of the gas space changes accordingly.

[0036] In particular, when the pressure of the coolant changes, the separating membrane deforms accordingly, with the result that the gas in the gas space is in particular compressed or expanded.

[0037] According to yet another embodiment, when viewed in cross section through the cooling line, the gas spaces separated by the elastic separating membranes are rotationally symmetrical.

[0038] Due to the embodiment in which the gas space, and therefore the gas volume, is rotationally symmetric, there is a system in which all forces acting on the gas bubble formed by the separation membrane and the gas in the gas space are balanced and no force is exerted.

[0039] According to yet another embodiment, when viewed in cross section of the cooling line, the liquid space and the gas space separated from the liquid space by the elastic separating membrane are arranged coaxially.

[0040] This improves the damping of pressure fluctuations due to gas volume.

[0041] According to yet another embodiment, when viewed in cross section of the cooling line, the gas space is an inner gas space or an outer gas space relative to the liquid space.

[0042] The advantage of the internal gas space and therefore the internal compressible gas volume is that the gas volume is located where the maximum flow velocity of the coolant occurs, and therefore the damping of pressure fluctuations in the coolant is particularly effective.

[0043] The advantage of an external gas space is that the gas space is more easily accessible from the outside and can therefore be more easily filled and / or refilled with gas. For example, gas can be introduced into the gas space via openings and / or valves in the wall of the cooling line.

[0044] In the internal gas space, the gas space is bounded only by the separating membrane and not by the inner wall of the cooling line, for example.

[0045] In the outer gas space, the gas space is bounded by both the separator membrane and the inner wall of the cooling line, for example.

[0046] According to yet another embodiment, the cooling device includes a resilient tube that includes a resilient separator membrane and serves to define a gas space.

[0047] This makes it particularly easy to realize a gas volume integrated into the cooling line.

[0048] For example, a gas space may be formed inside the tube (an example of an internal gas space), and a liquid space may be formed accordingly outside the tube (e.g., between the outer surface of the tube and the inner wall of the cooling line).

[0049] Alternatively, the gas space may be formed outside the tube (e.g., between the outer surface of the tube and the inner wall of the cooling line) (as an example of an external gas space), in which case a liquid space is correspondingly formed within the tube.

[0050] According to yet another embodiment, the cooling device comprises at least one spacer arranged between the elastic separation membrane and the inner wall of the cooling line.

[0051] The at least one spacer may improve the positioning of the elastic separation membrane in the cooling line, for example, even during operation of the cooling device. For example, the movement of the elastic separation membrane in the cooling line may be limited, particularly during operation of the cooling device (but deformation of the elastic separation membrane may not be limited). For example, there may be limitations on the position of the gas space relative to the liquid space. For example, the rotationally symmetrical and / or coaxial positioning of the gas space relative to the liquid space may be (e.g., substantially) maintained during operation.

[0052] The at least one spacer is arranged, for example, in the gas space or the liquid space.

[0053] The cooling device may also include multiple spacers, which may be positioned at one longitudinal position of the cooling line (e.g., radially) and / or at multiple longitudinal positions of the cooling line (e.g., spaced apart).

[0054] According to yet another embodiment, the cooling device includes a plurality of spacers formed by nubs disposed on the outer surface of the elastic separator membrane.

[0055] The bumps (e.g., protrusions) protrude, in particular from the outer surface of the elastic separation membrane, e.g., toward the inner wall of the cooling line and / or in the radial direction of the cooling line. For example, the bumps may be formed from the same material as the separation membrane. For example, the separation membrane can also be made integral with the bumps.

[0056] According to yet another embodiment, the cooling device comprises fastening means for attaching the elastic separating membrane to the inner wall of the cooling line.

[0057] This allows the position of the separation membrane to be limited and / or fixed within the cooling line. For example, the fixing means may also comprise or form at least one spacer.

[0058] According to yet another embodiment, the cooling device comprises a device for setting the pressure of the gas in the gas space.

[0059] This allows the gas pressure (pre-pressure) of the gas in the gas space, and therefore the damping frequency of the gas volume, to be accurately set. In particular, the set gas pressure is the gas pressure when the separation membrane is in a resting state (i.e., in a non-deformed state). The damping effect of the gas volume varies depending on the relative pressure between the gas pressure of the gas volume and the pressure of the liquid.

[0060] According to yet another embodiment, the cooling device comprises two or more elastic separating membranes, which are arranged in the cooling line and correspondingly form two or more gas spaces separated from each other and from the liquid space.

[0061] Pressure fluctuations can be damped even more accurately by providing multiple separate (e.g., closed) gas spaces and thus gas volumes, for example, the gas pressure of the gas can be different in the multiple gas spaces, so that pressure surges of different frequencies can be damped.

[0062] For example, the gas spaces, and therefore the gas volumes, can be precisely designed for each individual position-sensitive component. For example, the gas pressure of the gas in each gas space can be precisely set to attenuate the disturbance excitation of each position-sensitive component. For example, each gas space can be disposed adjacent to each position-sensitive component and upstream (e.g., immediately upstream) of each position-sensitive component with respect to the flow direction of the coolant.

[0063] According to yet another embodiment, when viewed in cross section of the cooling line, two or more gas spaces are separated from each other and from the liquid space, and / or Relative to the flow direction of the coolant, the two or more gas spaces are separated from each other and from the liquid space.

[0064] According to yet another embodiment, two or more gas spaces are separated from each other and from the liquid space relative to the flow direction of the cooling line, and the cooling device has a gas in each of the two or more gas spaces, each gas having a different pressure.

[0065] For example, the cooling device may comprise one or more devices configured to set the pressure of the gas in each gas space, e.g., this allows the gas pressure, and therefore the damping frequency, to be precisely set in each gas space.

[0066] According to yet another embodiment, the cooling device comprises a foam and / or sponge element having a plurality of gas bubbles and an elastic material surrounding the plurality of gas bubbles, the gas space being formed by the plurality of gas bubbles of the foam and / or sponge element, and the separating membrane being formed from the elastic material surrounding the plurality of gas bubbles.

[0067] The gas spaces separated by the separating membrane can be provided in an alternative manner as a result of foam and / or sponge elements.

[0068] According to yet another embodiment, the cooling device is configured such that the coolant flows through the cooling lines in a flow direction and the diameter of the cooling lines tapers in the flow direction.

[0069] As a result of this varying geometry of the cooling lines, the flow rate of the cooling liquid can be influenced and therefore the frequency range of the damping can be set.

[0070] For example, the diameter of the cooling lines tapers uniformly in the direction of flow.

[0071] For example, the cooling lines may extend longitudinally (straight) and the cooling fluid may flow longitudinally through the cooling lines. For example, the diameter of the cooling lines may taper longitudinally. Alternatively, the cooling lines may be curved, e.g., extending in a spiral (often referred to as a convolution). For example, the diameter of the cooling lines may taper along a spirally curved cooling line.

[0072] According to a second aspect, a lithographic apparatus, in particular an EUV lithographic apparatus, is proposed, the lithographic apparatus comprising a cooling device as described above.

[0073] The lithographic apparatus, for example, comprises at least one position-sensitive component.

[0074] According to a third aspect, a method for operating a cooling device is proposed, the cooling device serving to cool a position-sensitive component of a lithographic apparatus, the cooling device comprising a cooling line having a liquid space for transporting a cooling liquid to the position-sensitive component, a gas space for containing a gas, and an elastic separation membrane arranged in the cooling line and serving to separate the gas space from the liquid space. The method comprises: a) flowing a cooling liquid through a liquid space of the cooling line; b) changing the volume of the liquid space by deforming the elastic separation membrane in response to changes in pressure of the cooling liquid in the liquid space; Includes.

[0075] The change in volume of the liquid space particularly refers to the change in the volume of the cooling liquid in the liquid space.

[0076] The position-sensitive component is preferably a position-sensitive component of a projection optical unit of a lithographic apparatus (projection exposure apparatus), however, the position-sensitive component can also be a position-sensitive component of an illumination system of the lithographic apparatus.

[0077] According to a fourth aspect, there is proposed a temperature control device for controlling the temperature of a position sensitive component of a lithographic apparatus, the temperature control device comprising: a liquid line having a liquid space for delivering a temperature control liquid to the position sensitive component and a gas space for containing a gas; an elastic separation membrane disposed in the liquid line and serving to separate the gas space from the liquid space; Equipped with.

[0078] The temperature control device can be used to influence the thermal condition of the position-sensitive component. In particular, the position-sensitive component can be temperature-controlled, i.e., cooled or heated, using the temperature control device. The temperature control device is therefore a cooling device or a heating device. Furthermore, the temperature control liquid is accordingly a cooling liquid or a heating liquid.

[0079] Where this application refers to a cooling device, cooling, cooling fluid, cooling line, method of operating a cooling device, etc., corresponding references to a heating device, heating, heating fluid, heating line, method of operating a heating device, etc. may also be used.

[0080] In this case, "a(n)" should not necessarily be understood as being limited to exactly one element. Rather, there may be a plurality of elements, such as two, three, or more. Any other numbers used herein should not be understood as being strictly limited to the number of elements recited. Rather, unless otherwise specified, the number may be increased or decreased.

[0081] The embodiments and features described for the cooling device (first aspect) apply correspondingly to the other aspects (second, third and fourth aspects), and vice versa.

[0082] Further possible implementations of the present invention also include not explicitly mentioned combinations of the features or embodiments described above or below with respect to the exemplary embodiments. A person skilled in the art will also be able to add individual aspects as improvements or supplements to each basic form of the present invention.

[0083] Further advantageous configurations and aspects of the invention are the subject of the dependent claims and also of the exemplary embodiments of the invention described below. The invention is explained in more detail below on the basis of preferred embodiments with reference to the attached drawings. [Brief explanation of the drawings]

[0084] [Figure 1] 1 shows a schematic meridional section of a projection exposure apparatus for EUV projection lithography; [Figure 2]2 shows a positioning system with optical components of the projection exposure apparatus from FIG. 1 according to an embodiment; [Figure 3] 3 shows a cooling device for cooling the optical component from FIG. 2 according to one embodiment, the cooling device comprising a cooling line device with an integrated compressible gas volume. [Figure 4] A cross-sectional view of the functional principle of the cooling line equipment from Figure 3 is shown. [Figure 5] 4 shows a cross-sectional view of the cooling line equipment from FIG. 3, with the elastic separation membrane in a resting state. [Figure 6] 6 shows a view similar to FIG. 5, but with the elastic separation membrane in an elastically deformed state. [Figure 7] 4 shows a cross-sectional view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3. [Figure 8] 4 shows a cross-sectional view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3. [Figure 9] 4 shows a cross-sectional view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3. [Figure 10] 4 shows a cross-sectional view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3, in which the separation membrane includes a spacer. [Figure 11] 4 shows a perspective view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3, comprising fastening means according to a first variant. [Figure 12] 4 shows a perspective view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3, comprising fastening means according to a second variant. [Figure 13] 4 shows a cross-sectional view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3. [Figure 14] 4 shows a side view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3. [Figure 15] 4 shows a side view of yet another embodiment of the cooling line equipment of the cooling device from FIG. 3. [Figure 16] 2 shows a flowchart of a method for operating a cooling device of a projection exposure apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0085] Unless indicated to the contrary, identical or functionally identical elements are given the same reference numbers throughout the figures. It should also be noted that illustrations in the figures are not necessarily to scale.

[0086] 1 shows an embodiment of a projection exposure apparatus 1 (lithography apparatus), in particular an EUV lithography apparatus. An embodiment of an illumination system 2 of the projection exposure apparatus 1 comprises, in addition to a light source or radiation source 3, an illumination optical unit 4 which illuminates an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a module separate from the rest of the illumination system 2. In this case, the illumination system 2 does not include the light source 3.

[0087] 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, in particular in the scanning direction, by a reticle displacement drive 9.

[0088] For illustrative purposes, Figure 1 shows a Cartesian xyz coordinate system with an x-direction x, a y-direction y, and a z-direction z. The x-direction x extends perpendicular to the plane of the drawing. The y-direction y extends horizontally, and the z-direction z extends vertically. In Figure 1, the scanning direction extends in the y-direction y. The z-direction z extends perpendicular to the object plane 6.

[0089] The projection exposure apparatus 1 comprises a projection optical unit 10. The projection optical unit 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 extends 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.

[0090] The structures on the reticle 7 are imaged onto a photosensitive layer of a wafer 13 arranged in the region of the image field 11 of the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable, in particular in the y-direction, by a wafer displacement drive 15. The displacement of the reticle 7 by the reticle displacement drive 9 on the one hand and the displacement of the wafer 13 by the wafer displacement drive 15 on the other hand can be performed synchronously with one another.

[0091] The light source 3 is an EUV radiation source. The light source 3 emits in particular EUV radiation 16, also referred to in the following as working radiation, illumination radiation or illumination light. The working radiation 16 has in particular a wavelength in the range of 5 nm to 30 nm. The light source 3 can be a plasma source, for example an LPP (Laser Produced Plasma) source or a GDPP (Gas Discharge Plasma) source. It can also be a synchrotron-based radiation source. The light source 3 can be a free electron laser (FEL).

[0092] The illumination radiation 16 leaving the light source 3 is focused by the collector 17. The collector 17 may be a collector with one or more ellipsoidal and / or hyperbolic reflecting surfaces. The illumination radiation 16 may be incident on at least one reflecting surface of the collector 17 at grazing incidence (GI), i.e., at an angle of incidence greater than 45°, or at normal incidence (NI), i.e., at an angle of incidence smaller than 45°. The collector 17 may be structured and / or coated to optimize its reflectivity for the radiation used and to suppress extraneous light.

[0093] 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 be a separation point between the radiation source module, including the light source 3 and the collector 17, and the illumination optics unit 4.

[0094] The illumination optical unit 4 comprises a deflection mirror 19 and a first facet mirror 20 arranged downstream thereof in the beam path. The deflection mirror 19 can be a plane deflection mirror or a mirror with a beam-influencing effect beyond a pure deflection effect. Alternatively or additionally, the deflection mirror 19 can be in the form of a spectral filter that separates the used optical wavelength of the illumination radiation 16 from extraneous light of wavelengths outside of it. If the first facet mirror 20 is arranged in a plane of the illumination optical unit 4 that is optically conjugate with the object plane 6 as a field plane, this facet mirror is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, also referred to as field facets in the following. Only some of these first facets 21 are shown by way of example in FIG. 1 .

[0095] The first facet 21 may take the form of a macroscopic facet, in particular a rectangular facet, or a facet with an arcuate or part-circular edge profile. The first facet 21 may take the form of a planar facet or a convexly or concavely curved facet.

[0096] The first facet 21 itself can also consist of a number of individual mirrors, in particular a number of micromirrors, as is known, for example, from DE 10 2008 009 600. The first facet mirror 20 can in particular take the form of a microelectromechanical system (MEMS system). See DE 10 2008 009 600 for further details.

[0097] Between the collector 17 and the deflection mirror 19, the illumination radiation 16 propagates horizontally, ie in the y-direction y.

[0098] A second facet mirror 22 is arranged downstream of the first facet mirror 20 in the beam path of the illumination optical unit 4. If the second facet mirror 22 is arranged in the pupil plane of the illumination optical unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged away from the 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 reflector. Specular reflectors are known from US Patent Application Publication No. 2006 / 0132747, EP 1 614 008 and US 6,573,978.

[0099] The second facet mirror 22 includes 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.

[0100] The second facet 23 may likewise be a macroscopic facet which may have, for example, a circular, rectangular or hexagonal boundary, or may be a facet made up of a micromirror - see also DE 10 2008 009 600 A1 for further details.

[0101] The second facet 23 may have a flat reflecting surface or a convexly or concavely curved reflecting surface.

[0102] The illumination optical unit 4 therefore forms a double-faceted system, this basic principle also being called a fly's eye integrator.

[0103] It may be advantageous not to arrange the second facet mirror 22 exactly in a plane that is optically conjugate with the pupil plane of the projection optical unit 10. In particular, the second facet mirror 22 may be arranged so that it is tilted with respect to the pupil plane of the projection optical unit 10, as described, for example, in DE 10 2017 220 586 A1.

[0104] The individual first facets 21 are imaged into the object field 5 by means of a second facet mirror 22. The second facet mirror 22 is the last beam-shaping mirror in the beam path upstream of the object field 5 or indeed the final mirror for the illumination radiation 16.

[0105] In a further embodiment, not shown, of the illumination optical unit 4, a transfer optical unit, which in particular contributes to the imaging of the first facet 21 into the object field 5, can be arranged in the beam path between the second facet mirror 22 and the object field 5. The transfer optical unit can have exactly one mirror or two or more mirrors arranged one after the other in the beam path of the illumination optical unit 4. The transfer optical unit can in particular comprise one or two normal incidence mirrors (NI mirrors) and / or one or two grazing incidence mirrors (GI mirrors).

[0106] In the embodiment shown in FIG. 1, downstream of the collector 17 the illumination optical unit 4 comprises exactly three mirrors, in particular a deflection mirror 19 , a first facet mirror 20 and a second facet mirror 22 .

[0107] In yet another embodiment of the illumination optical unit 4, the deflection mirror 19 can also be omitted, so that the illumination optical unit 4 then has exactly two mirrors downstream of the collector 17, specifically a first facet mirror 20 and a second facet mirror 22.

[0108] The imaging of the first facet 21 onto the object plane 6 by the second facet 23 or by means of the second facet 23 and the transfer optical unit is generally only an approximate imaging.

[0109] The projection optical unit 10 comprises a number of mirrors Mi, which are numbered consecutively according to their location in the beam path of the projection exposure apparatus 1 .

[0110] 1, the projection optical unit 10 includes six mirrors M1 to M6. 4, 8, 10, 12 or any other number of mirrors Mi are equally possible. The projection optical unit 10 is a double-shielded optical unit. The penultimate mirror M5 and the final mirror M6 each have a passage aperture for the illumination radiation 16. The projection optical unit 10 has an image-side numerical aperture that is greater than 0.5, may be greater than 0.6, and may be, for example, 0.7 or 0.75.

[0111] The reflective surface of the mirror Mi can be embodied as a freeform surface without an axis of rotational symmetry. Alternatively, the reflective surface of the mirror Mi can be designed as an aspheric surface, with exactly one axis of rotational symmetry of the reflective surface shape. Like the mirrors of the illumination optical unit 4, the mirror Mi can have a coating that is highly reflective with respect to the illumination radiation 16. These coatings can take the form of multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0112] The projection optical unit 10 has a large object-image offset in the y-direction y between the y-coordinate of the center of the object field 5 and the y-coordinate of the center of the image field 11. This object-image offset in the y-direction y can be approximately as large as the z-distance between the object plane 6 and the image plane 12.

[0113] In particular, the projection optical unit 10 can have an anamorphic configuration. In particular, it has different imaging scales βx, βy in the x-direction x and the y-direction y. The two imaging scales βx, βy of the projection optical unit 10 are preferably (βx, βy)=(+ / -0.25, + / -0.125). A positive imaging scale β means imaging without image inversion. A negative sign of the imaging scale β means imaging with image inversion.

[0114] The projection optical unit 10 results in a size reduction in the x-direction, ie perpendicular to the scanning direction, by a ratio of 4:1.

[0115] The projection optical unit 10 provides a size reduction of 8:1 in the y-direction, ie the scanning direction.

[0116] Other imaging scales are possible as well, such as imaging scales of the same sign and magnitude in the x-direction x and the y-direction y, for example 0.125 or 0.25.

[0117] The number of intermediate image planes in the x-direction x and y-direction y in the beam path between the object field 5 and the image field 11 may be the same or may differ depending on the design of the projection optical unit 10. An example of a projection optical unit with a different number of such intermediate images in the x-direction x and y-direction y is known from US Patent Application Publication No. 2018 / 0074303.

[0118] Each of the second facets 23 is assigned to exactly one of the first facets 21 to form a respective illumination channel that illuminates the object field 5. In particular, this allows illumination according to the Köhler principle to be obtained. The far field is decomposed into a plurality of object fields 5 by means of the first facets 21. The first facets 21 generate a plurality of images of intermediate foci on the respectively assigned second facets 23.

[0119] The first facets 21 are respectively imaged onto the reticle 7 by the assigned second facets 23 in an overlapping manner in order to illuminate the object field 5. The illumination of the object field 5 is in particular as uniform as possible. Its uniformity error is preferably less than 2%. By overlapping the different illumination channels, field uniformity can be achieved.

[0120] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by the arrangement of the second facets 23. By selecting the illumination channels to be guided, in particular a subset of the second facets 23, the intensity distribution at the entrance pupil of the projection optical unit 10 can be set. This intensity distribution is also referred to as the illumination setting.

[0121] A similarly favorable pupil uniformity in the region of a defined illuminated portion of the illumination pupil of the illumination optical unit 4 can be achieved by redistribution of the illumination channels.

[0122] Further aspects and details of the illumination of the object field 5, in particular the entrance pupil of the projection optical unit 10, are explained below.

[0123] The projection optical unit 10 may in particular have a concentric entrance pupil, which may be accessible, or which may be inaccessible.

[0124] The entrance pupil of the projection optical unit 10 generally cannot be illuminated exactly using the second facet mirror 22. In the case of imaging of the projection optical unit 10 telecentrically imaging the center of the second facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find a surface at which the determined separation between pairs of aperture rays is minimal. This surface represents the entrance pupil or a surface conjugate to it in real space. In particular, this surface exhibits a finite curvature.

[0125] The projection optical unit 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 transfer optical unit, should be provided between the second facet mirror 22 and the reticle 7. This optical element can be used to take into account the different positions of the tangential and sagittal entrance pupils.

[0126] 1 of the components of the illumination optical unit 4, the second facet mirror 22 is arranged in a plane conjugate with the entrance pupil of the projection optical unit 10. The first facet mirror 20 is arranged at an angle with respect to the object plane 6. The first facet mirror 20 is arranged at an angle with respect to the arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged at an angle with respect to the arrangement plane defined by the second facet mirror 22.

[0127] FIG. 2 illustrates a positioning system 100 having an optical component 102 (as an example of a position-sensitive component) according to one embodiment.

[0128] The optical component 102 is for example a mirror of the projection exposure apparatus 1 (lithography apparatus) from Fig. 1, in particular of the projection optical unit 10. For example, the optical component 102 is one of the mirrors M1 to M6. In the following, the optical component 102 will be described as a mirror. However, in other examples it could also be an optical component other than a mirror.

[0129] 2, mirror 102 includes a coating 104 having an optically active surface 106. Mirror 102 also includes a substrate 108. Cooling lines 110 are disposed within substrate 108 through which a cooling fluid 112, such as water, is conducted to actively cool mirror 102. Cooling mirror 102 serves to prevent thermal deformation of mirror 102 even when irradiated with high-energy EUV radiation 16 (FIG. 1).

[0130] The mirror 102 is movably mounted to a force frame 116 by an actuator device 114. The actuator device 114 includes, for example, a plurality of actuators 118 and a drive unit (not shown). The actuator device 114 serves, for example, to position the mirror 102 with respect to six degrees of freedom (translation in the X, Y, and Z directions and rotation about the X, Y, and Z directions).

[0131] The positioning system 100 further includes a sensor device 120 that captures the current position of the mirror 102. The sensor device 120 is only shown diagrammatically in FIG. 2. The sensor device 120 includes one or more sensors, such as interferometers. The sensors of the sensor device 120 are mounted, for example, on a sensor frame (not shown). The sensor frame is mounted, for example, to the force frame 116 so as to be vibrationally decoupled. For example, the current position of the mirror 102 is captured using a laser beam 122.

[0132] FIG. 3 shows a cooling apparatus 200 for cooling the mirror 102. The cooling apparatus comprises a cooling circuit 202. The cooling apparatus 200 comprises a cooling unit 204 for cooling the cooling liquid 112 (FIG. 2) and cooling lines 206, 110 for transporting the cooling liquid 112. The cooling apparatus 200 further comprises one or more pumps 208 for generating a required coolant flow rate of the cooling liquid 112. The cooling apparatus 202 further comprises one or more valves 210 for controlling the cooling flow. The cooling apparatus 200 may serve to cool multiple components of the lithographic apparatus 1. By way of example, the mirror 102 from FIG. 2 is shown in FIG. 3 as the cooled component. The cooling lines 110 (FIG. 2) arranged in the mirror substrate 108 are shown schematically in FIG. 3. Furthermore, two further mirrors 102′, 102″ similar to the mirror 102 from FIG. 2 are shown by way of example in FIG. 3 as further cooled components.

[0133] Pumps in the cooling system 200, such as pump 208, induce local pressure fluctuations in the liquid 112, thereby exciting dynamic disturbances. These pressure fluctuations are transmitted throughout the cooling circuit 202 via longitudinal waterborne acoustic waves. Additionally, cross-sectional changes in the cooling lines 206 (not shown), bends 212 in the cooling lines 206, and valves 210 in the cooling system 200 can also be sources of disturbances that induce local pressure fluctuations in the liquid 112. These acoustic disturbance excitations are transmitted to the cooled components 102, 102′, 102″ (mirrors 102, 102′, 102″) via waterborne acoustic waves. This can lead to changes in the position of each mirror 102, 102′, 102″, causing the actual position of each mirror 102, 102′, 102″ to deviate from its target position.

[0134] 3 and in the following description, the cooling device 200 serves by way of example to cool the mirrors 102, 102', 102''. However, in other examples, the cooling device 200 may also serve to cool other position-sensitive components of the projection exposure apparatus 1 (lithographic apparatus), such as other mirrors and / or a sensor frame (not shown).

[0135] To damp pressure fluctuations in the cooling liquid 112, the cooling device 200 includes a cooling line equipment 214 having an integrated compressible gas volume 216. In particular, the cooling line equipment 214 includes the cooling line 206 or a portion of the cooling line 206, a liquid space 218 through which the cooling liquid 112 can flow, and a gas space 220 for containing a gas 222 (gas volume 216). Additionally, the cooling line equipment 214 includes an elastic separator membrane 224 that serves to separate the gas space 220 from the liquid space 218.

[0136] Figure 4 illustrates the functional principle of the cooling line device 200' from Figure 3. The left side of Figure 4 shows a cooling line device 214' with a cooling line 206' and a static elastic separator membrane 224' disposed within the cooling line 206'. In particular, the elastic separator membrane 224' on the left side of Figure 4 is in a relaxed, undeformed state. The elastic separator membrane 224' separates the cooling liquid 112 in the liquid space 218' from the gas 222 in the gas space 220'. The volume of the cooling liquid 112 is at static V F1 The volume of the gas 222 is at rest V G1 is located.

[0137] 4 shows a cooling line device 214' with an elastic separator membrane 224' in an elastically deformed state. Increasing the pressure of the cooling liquid 112 causes the separator membrane 224' to expand to a volume V of the liquid space 218'. F2 As the volume of the gas space 220' increases, V G2 Therefore, the increase in pressure of the cooling liquid 112 can be attenuated by the expansion of the liquid 112 and the compression of the gas 222 in the gas space 220'.

[0138] 4 uses dashed lines to indicate that when the pressure of the cooling liquid 112 in the liquid space 218' decreases, the separation membrane 224' deforms, thereby increasing the volume of the gas space 220'. Therefore, cyclic pressure fluctuations in the cooling liquid 112 can also be damped using the compressible gas bubbles 216'.

[0139] 5 shows a cross-sectional view of the cooling line device 214 from FIG. 3 along line VV. In this embodiment, the elastically deformable membrane 224 is a tube 226 having a gas 220 positioned in its interior 228. The gas space 220 is therefore an interior gas space 220 relative to the liquid space 218. The liquid space 218, through which the cooling liquid 112 flows, is formed between an outer wall 230 of the tube 226 and an inner wall 232 of the cooling line 206.

[0140] Furthermore, in this embodiment, the gas space 220 is arranged and embodied rotationally symmetrically with respect to the cooling line 206. In particular, the gas space 220, the liquid space 218, and the cooling line 206 are arranged coaxially with each other. In Figure 5, the central axis of the cooling line 206 is indicated by reference character A1, the central axis of the liquid space 218 is indicated by reference character A2, and the central axis of the gas space 220 is indicated by reference character A3.

[0141] 5, the elastic separator 224 (i.e., the tube 226) is in a stationary state. The volume of the gas 222 is V G1’ and the volume of the coolant 112 is V FI’ is.

[0142] 6 shows the cooling line equipment 214 from FIG. 5 with the elastic separator membrane 224 in an elastically deformed state. By increasing the pressure of the cooling liquid 112, the separator membrane 224 is forced to expand beyond the volume V of the liquid space 218. FI’ As the volume of the gas space 220 increases, V G2’ The tube 226 is deformed so that the diameter D of the tube 226 containing the separation membrane 224 is accordingly reduced. In particular, the diameter D of the tube 226 containing the separation membrane 224 is reduced. Due to the rotational symmetry, the increase in pressure of the coolant 112 acts uniformly on the tube 226. As a result, the increase in pressure of the coolant 112 can be well attenuated by the compression of the gas 222 in the gas space 220.

[0143] 7 shows a cross-sectional view of yet another embodiment of a cooling line arrangement 314 of a cooling arrangement 300 of a lithographic apparatus 1. The cooling line arrangement 314 comprises a cooling line 306 having an outer gas space 320 relative to a liquid space 318. In particular, the separation membrane 324 in this embodiment is embodied in the form of a tube 326. This is yet another example of a rotationally symmetric gas space 220.

[0144] 8 shows a cross-sectional view of yet another embodiment of a cooling line arrangement 414 of a cooling device 400 of a lithographic apparatus 1. The cooling line arrangement 414 includes a cooling line 406 having two coaxially arranged separation membranes 424 and 424'. The two separation membranes 424 and 424' can also be said to be coaxial when viewed in cross section of the cooling line 406. In this embodiment, when viewed in cross section of the cooling line 406, three spaces separated from each other by the two separation membranes 424 and 424' are obtained: two gas spaces 420 and 420' for containing the gas 222, and a liquid space 418 for flowing the coolant 112. In particular, the liquid space 418, which has a ring-shaped cross section, is in contact with the gas space 420 and the gas space 420' on both sides, i.e., on both its inner surface 434 and outer surface 436, respectively, for pressure equalization.

[0145] In a variation (not shown) of the embodiment of FIG. 8, a ring-shaped gas space can also be sandwiched between two liquid spaces.

[0146] Figure 9 shows a cross-sectional view of yet another embodiment of a cooling line arrangement 514 of a cooling apparatus 500 of a lithographic apparatus 1. The cooling line arrangement 514 includes a cooling line 506 having two separation membranes 524 and 524' in the form of tubes 526 and 526', respectively. However, unlike the embodiment of Figure 8, the separation membranes 524 and 524' are arranged side by side rather than coaxially in the cross-sectional view. Each of the tubes 526 and 526' is filled with a gas 222 to provide a compressible gas volume 516 and 516' for damping pressure fluctuations in the coolant liquid 112. The embodiment shown in Figure 9 is an example of two interior gas spaces 520 and 520'.

[0147] 9 embodiment (not shown), there may be two liquid spaces formed within the tubes 526, 526′. Additionally, there may be a gas space disposed between the outer walls 530, 530′ of the tubes 526, 526′ and the inner wall 532 of the cooling line 506.

[0148] FIG. 10 shows a cross-sectional view of yet another embodiment of a cooling line arrangement 614 of the cooling device 600 of the lithographic apparatus 1. The cooling line arrangement 614 is a variant of the cooling line arrangement 214 shown in FIG. 5. The cooling line arrangement 614 according to the embodiment of FIG. 10 differs from the cooling line arrangement 214 according to the embodiment of FIG. 5 in that a plurality of spacers 638 are arranged on the separation membrane 624. For example, three of the spacers 638 shown in FIG. 10 are labeled with reference numerals. In particular, the spacers 638 are arranged between the outer wall 630 of the elastic separation membrane 624 and the inner wall 632 of the cooling line 606. For example, the spacers 638 are formed by humps 640 arranged on the outer wall 630 of the elastic separation membrane 624. In particular, the humps 640 can be made of the same material as the elastic separation membrane 624. For example, the humps can be formed integrally with the elastic separation membrane 624.

[0149] 11 shows a perspective view of yet another embodiment of a cooling line device 714 of a cooling device 700 of a lithographic apparatus 1. The cooling line device 714 includes, inter alia, a fastening means 742 for attaching an elastic separation membrane 724 to an inner wall 732 of a cooling line 706. The elastic separation membrane 724 is particularly embodied in the form of a tube 726. The fastening means 742 further includes, for example, a pipe clamp 744 that is arranged around and clamps the tube 726. The fastening means 742 further includes, for example, a post and / or a connecting piece 746 that connects the pipe clamp 744 to the inner wall 732 of the cooling line 706. In particular, the post / connecting piece 746 is attached on one side to the pipe clamp 744 and connected on the other side to the inner wall 732 of the cooling line 706. In particular, the post / connecting piece 746 is an example of a spacer that holds the tube 726 in place within a liquid space 718 filled with the coolant 112.

[0150] Figure 12 shows a perspective view of yet another embodiment of a cooling line arrangement 814 of a cooling device 800 of a lithographic apparatus 1. The cooling line arrangement 814 comprises yet another variant of a fixing means 842. The fixing means 842 comprises struts 844 arranged between an outer wall 830 of the separation membrane 824 and an inner wall 832 of the cooling line 806. The struts are arranged in particular radially. Five struts are shown by way of example in Figure 12, three of which are labeled with reference numerals. Figure 12 shows an inner gas space 820 surrounded by a ring-shaped liquid space 818. However, this arrangement can also be reversed so that there is an outer gas space and an inner liquid space.

[0151] The embodiments of cooling line equipment 214, 214', 214'', 314, 414, 514, 614, 714, and 814 shown in Figures 3-12 can be combined in many ways. For example, spacer 638 shown in Figure 10, fastening means 742 shown in Figure 11, and fastening means 842 shown in Figure 12 can be combined with each of the embodiments and variations shown and / or described in connection with Figures 3-9.

[0152] 8 and 9 show two examples of cooling line equipment 414 and 514 that include two or more separator membranes 424 and 524 to provide two or more gas spaces 420 and 520 for attenuating pressure fluctuations in the cooling liquid 112 when viewed in cross section of the cooling line 406 and 506. In particular, FIGS. 8 and 9 show two separator membranes 424 and 424' and 524 and 524', respectively, to form two gas spaces 420 and 420' and 520 and 520', respectively. However, three or more separator membranes may be provided so that three or more spaces are provided when viewed in cross section of the cooling line 406 and 506.

[0153] As shown in FIG. 3 , additionally or alternatively, three or more separation membranes 224, 224″ may be provided so as to be separated from each other and from the liquid space 218 relative to the flow direction (flow direction) R of the cooling line 112. Furthermore, the cooling device 200 may include two or more gas spaces 220, 220″ separated from the liquid space 218 using two or more separation membranes 224, 224″. In particular, the two or more gas spaces 220, 220″ are separated from each other and from the liquid space 218 relative to the flow direction (flow direction) R of the cooling liquid 112. Gases 222, 222″ are contained in the two or more gas spaces 220, 220″, respectively, and the gases 222, 222″ may have different pressures P, P″ from each other. The pressures P, P″ particularly refer to the pressures (pre-pressures) of the gases 222, 222″ when the separation membranes 224, 224″ are in a stationary state.

[0154] By providing multiple gas volumes 216, 216″ in the cooling circuit 202 with different pre-pressures P, P″, pressure fluctuations in the coolant 112 within the cooling circuit 202 can be precisely damped. In particular, the pre-pressures P, P″ of each gas volume 216, 216″ can be set to set the frequency range of damping. For example, the first gas volume 216 in the cooling circuit 202 of FIG. 3 can dampen low-frequency pressure surges. For example, it is known that excitations from water cabinets tend to be low-frequency in nature. Therefore, the first gas volume 216 can be specifically designed to suppress low frequencies, which can be achieved as close as possible to the water cabinet.

[0155] Furthermore, high-frequency pressure surges can be attenuated, for example, by a second gas volume 216'' in the cooling circuit 202 of FIG. 3. In particular, the pre-pressure P'' of the second gas volume 216'' is set to a value greater than the pre-pressure P of the first gas volume 216 for this purpose. It is known that there is a sensitive frequency range from approximately 50 Hz to 150 Hz due to position control of the mirror 102. Therefore, a second gas volume 216'' that exhibits good suppression in precisely this frequency range can be located immediately upstream of an actively controlled and cooled mirror 102.

[0156] For example, cascading of pressure damping within the cooling circuit 202 can also be achieved in this manner, where low frequency pressure fluctuations, e.g., as viewed in the flow direction R of the coolant 112, are damped first (e.g., by the first gas volume 216). Subsequently, downstream in the flow direction R, e.g., high frequency pressure fluctuations are damped (e.g., by the second gas volume 216'').

[0157] 3 shows two gas volumes 216, 216" with different pre-pressures P, P" and therefore different damping characteristics. However, three or more gas volumes 216, 216" with different pre-pressures P, P" and damping characteristics may be provided in the cooling circuit 202.

[0158] Furthermore, the gas volumes 216, 216" can be specifically tailored to the attenuation requirements of the individual position-sensitive components 102, 102', 102". In FIG. 3, the three gas volumes 216" upstream of the three optical components 102, 102', 102" in the flow direction R have equal pre-pressures P". However, each pre-pressure P" of the gas volumes 216" can also be specifically tailored to the attenuation requirements of each optical component 102, 102', 102".

[0159] 3 using dashed lines, the cooling apparatus 200 may include one or more devices 250 for setting the pressure P, P" of the gas 222, 222" in the one or more gas volumes 216, 216". The damping characteristics of the enclosed gas volumes 216, 216" throughout the cooling circuit 202 may be selectively set by the one or more pressure setting devices 250. For example, pre-pressures P, P" may be set prior to operating the cooling apparatus 200 and / or the lithographic apparatus 1.

[0160] Although not shown in Figures 4-12, embodiments of the cooling devices 300, 400, 500, 600, 700, 800 may include one or more devices 250 (Figure 3) for setting the pressure of the gas 222 in one or more gas spaces 320, 420, 420', 520, 520', 620, 720, 820.

[0161] In each case, when viewed in the flow direction, Figures 3 to 12 show enclosed gas spaces 320, 420, 420', 520, 520', 620, 720, 820. However, in other examples, a single gas space may run through the entire cooling circuit 202.

[0162] 13 shows a cross-sectional view of yet another embodiment of a cooling line device 914 of a cooling device 900 of a lithographic apparatus 1. The cooling device 900 comprises a cooling line 906 having a liquid space 918, a gas space 920, and a separation membrane 924 separating the liquid space 918. According to this embodiment, the cooling device 900 further comprises a foam and / or sponge element 952. The foam and / or sponge element 952 includes a plurality of air bubbles 954 (gas bubbles 954) and an elastic material 956 surrounding the plurality of air bubbles 954. The gas space 920 is formed in particular by the plurality of air bubbles 954 of the foam and / or sponge element 952. Furthermore, the elastic material 956 surrounding the plurality of air bubbles 954 forms the separation membrane 924.

[0163] FIG. 14 shows a side view of yet another embodiment of a cooling line device 1014 of a cooling device 1000 of a lithographic apparatus 1. The cooling device 1000 comprises a cooling line 1006. Although not shown in FIG. 14, the cooling line 1006, like the cooling lines described above, includes a liquid space, a gas space, and a separation wall separating the liquid space. According to this embodiment, the cooling device 1000 is configured to direct a cooling liquid through the cooling line 1006 in a flow direction R. Furthermore, a diameter D1 of the cooling line 1006 tapers (e.g., uniformly) in the flow direction R. Reference symbol D1 denotes a first diameter, and D2 denotes a second diameter smaller than the first diameter D1. The flow velocity of the cooling liquid can be influenced by the taper of the cooling line diameter D1. In this way, the frequency range of the attenuation of pressure waves in the cooling liquid can be set.

[0164] 14, the cooling lines 1006 extend linearly in the longitudinal direction L, and the coolant flows through the cooling lines 1006 in the longitudinal direction L. In other words, the flow direction R and the longitudinal direction L are arranged parallel to each other in this case. In FIG. 14, the diameter D1 of the cooling lines 1006 tapers in the longitudinal direction L.

[0165] FIG. 15 shows yet another variation of the cooling lines 1114 of the cooling device 1100, which taper in the flow direction R' of the coolant. In particular, the cooling lines 1114 of FIG. 15 are curved. In the example shown, the cooling lines 1114 are shaped like a spiral W. The diameter D1 of the cooling lines 1114 tapers along the spiral W-shaped curve of the cooling lines 1114. Reference symbol D1' denotes a first diameter, and D2' denotes a second diameter smaller than the first diameter D1'.

[0166] In the following, with reference to Figure 16, a method of operating the cooling devices 200, 200', 300, 400, 500, 600, 700, 800, 900, 1000, 1100 (Figures 4 to 15) of the projection exposure apparatus 1 (Figure 1) according to an embodiment will be described. The cooling devices 200, 200', 300, 400, 500, 600, 700, 800, 900, 1000, 1100 serve to cool the position-sensitive components 102, 102', 102'' (Figure 3) of the projection exposure apparatus 1 (Figure 1).

[0167] The cooling devices 200, 200', 300, 400, 500, 600, 700, 800, 900, 1000, 1100 include cooling line equipment 214, 214', 314, 414, 514, 614, 714, 814, 914, 1014, 1114 (Figures 4 to 15) having cooling lines 206, 206', 306, 406, 506, 606, 706, 806, 906, 1006, 1106. The cooling line equipment 214, 214', 314, 414, 514, 614, 714, 814, 914, 1014, 1114 further includes a liquid space 218, 218', 318, 418, 518, 618, 718, 818, 918 for communicating the cooling liquid 112 to the position sensitive component 102, 102', 102''. To damp pressure fluctuations in the cooling liquid 112, the cooling line equipment 214, 214', 314, 414, 514, 614, 714, 814, 914, 1014, 1114 further includes one or more gas spaces 220, 220', 320, 420, 420', 520, 520', 620, 720, 820, 920 for containing a gas 222. Each gas space 220, 220', 320, 420, 420', 520, 520', 620, 720, 820, 920 is separated from the liquid space 218, 218', 318, 418, 518, 618, 718, 818, 918 by an elastic separator membrane 224, 224', 324, 424, 424', 524, 524', 624, 724, 824, 924.

[0168] In a first step S1 of the method, the cooling liquid 112 flows through the liquid spaces 218, 218', 318, 418, 518, 618, 718, 818, 918 of the cooling lines 206, 206', 306, 406, 506, 606, 706, 806, 906, 1006, 1106.

[0169] In a second step S2 of the method, the volume V of the liquid space 218, 218′, 318, 418, 518, 618, 718, 818, 918 is F1 (Therefore, the volume V of the coolant 112 F1) is changed by deformation of the elastic separation membrane 224, 224', 324, 424, 424', 524, 524', 624, 724, 824, 924. In particular, the volume V of the liquid space 218, 218', 318, 418, 518, 618, 718, 818, 918 F1 changes according to the pressure change of the cooling liquid 112. The volume V of the liquid spaces 218, 218′, 318, 418, 518, 618, 718, 818, and 918 F1 , and therefore the volume V of the coolant 112 F1 By varying the pressure, changes in pressure, e.g., pressure fluctuations, of the cooling fluid 112 can be damped, thereby reducing or preventing transmission of pressure fluctuations to the position sensitive component 102, 102', 102''.

[0170] Although the present invention has been described with reference to exemplary embodiments, it can be varied in many ways. [Explanation of symbols]

[0171] 1. Projection exposure equipment 2. Lighting system 3 light source 4. Illumination optical unit 5 Object field of view 6 Object plane 7 Reticle 8 Reticle Holder 9 Reticle Displacement Drive 10 Projection optical unit 11 Image field 12 Image plane 13 wafers 14 wafer holder 15 Wafer Displacement Drive 16 Lighting Radiation 17 Collector 18 Intermediate focal plane 19 Deflecting mirror 20 First Facet Mirror 21 First Facet 22 Second Facet Mirror 23 Second Facet 100 Positioning System 102, 102', 102'' Optical Components 104 Coating 106 Optically active surface 108 PCB 110, 110', 110'' cooling lines 112 Coolant 114 Actuator Equipment 116 Force Frame 118 Actuator 120 Sensor Equipment 122 Laser Beam 200 Cooling device 202 Cooling circuit 204 Cooling Unit 206 Cooling Line 208 Pump 210 Valve 212 bend 214, 214' Cooling Line Equipment 216, 216', 216'' Gas volume 218, 218' liquid space 220, 220', 220'' gas space 222, 222'' gas 224, 224', 224'' separation membrane 226 tubes 228 Internal 230 Exterior Wall 232 Interior wall 250 equipment (pressure setting equipment) 300 Cooling device 306 Cooling Line 314 Cooling Line Equipment 316 Gas Volume 318 Liquid space 320 Gas Space 324 Separation membrane 326 tubes 400 Cooling device 406 Cooling Line 414 Cooling Line Equipment 416 Gas Volume 418 Liquid space 420, 420' gas space 424, 424' Separation membrane 434 Inside 436 Exterior 500 Cooling device 506 Cooling Line 514 Cooling Line Equipment 516 Gas Volume 518 Liquid space 520 Gas Space 524, 524' separation membrane 526, 526' Tube 530, 530' exterior wall 532 Interior wall 600 Cooling device 606 Cooling Line 614 Cooling Line Equipment 616 Gas Volume 618 Liquid space 620 Gas Space 624 Separation membrane 630 Exterior wall 632 Interior wall 638 Spacer 640 Hump 700 Cooling device 706 Cooling Line 714 Cooling Line Equipment 716 Gas Volume 718 Liquid space 720 Gas Space 724 Separation membrane 726 tubes 732 Interior wall 742 Fixing means 744 Pipe Clamp 746 Connecting Piece / Support 800 Cooling device 806 Cooling Line 814 Cooling Line Equipment 816 Gas Volume 818 Liquid space 820 Gas Space 824 Separation membrane 830 Exterior wall 832 Interior wall 842 Fixing means 844 Post 900 Cooling device 906 Cooling Line 914 Cooling Line Equipment 918 Liquid space 920 Gas Space 924 Separation membrane 952 elements 954 bubbles 956 Material 1000 cooling device 1006 Cooling Line 1100 Cooling device 1106 Cooling Line A1~A3 axis D diameter D1,D1' Diameter D2, D2' diameter L longitudinal axis M1~M6 mirrors P, P'' pressure R, R' flow direction S1, S2 method steps V F1 , V F1’ volume, capacity V F2 , V F2’ volume, capacity V G1 , V G1’ volume, capacity V G2 , V G2’ volume, capacity W spiral shape X direction Y direction Z direction

Claims

1. A cooling device (200) for cooling a position-sensitive component (102) of a lithography apparatus (1), A cooling line (206) having a liquid space (218) for transporting coolant (112) to the position-sensitive component (102) and a gas space (220) for containing gas (222), wherein the cooling line (206) is a conduit in which the cross-section is constant in the flow direction of the coolant (112) within the cooling line (206), An elastic separation membrane (224) is placed within the cooling line (206) and serves to separate the gas space (220) from the liquid space (218). A cooling device equipped with the following features.

2. A cooling device according to claim 1, wherein the elastic separation membrane (224) is a pressure membrane configured to deform so that when the pressure of the coolant (112) changes, the volume (VG1', VG2') of the gas space (220) changes accordingly.

3. A cooling device according to claim 1 or 2, wherein, when viewed in cross-section of the cooling line (206), the gas space (220) separated by the elastic separation membrane (224) is rotationally symmetric.

4. A cooling device according to claim 1 or 2, wherein, when viewed in cross-section of the cooling line (206), the liquid space (218) and the gas space (220) separated from the liquid space (218) by the elastic separation membrane (224) are arranged coaxially.

5. A cooling device according to claim 1 or 2, wherein, when viewed in cross-section of the cooling line (206, 306), the gas space (220, 320) is either an internal gas space (220) or an external gas space (320) relative to the liquid space (218, 318).

6. A cooling device according to claim 1 or 2, comprising an elastic tube (226) that includes the elastic separation membrane (224) and functions to form the gas space (220).

7. A cooling device according to claim 1 or 2, further comprising at least one spacer (638) disposed between the elastic separator membrane (624) and the inner wall (632) of the cooling line (606).

8. A cooling device according to claim 7, comprising a plurality of spacers (638) formed by bumps (640) arranged on the outer surface (630) of the elastic separation membrane (624).

9. A cooling device according to claim 1 or 2, further comprising fixing means (742, 842) for attaching the elastic separation membrane (724, 824) to the inner wall (732, 832) of the cooling line (706, 806).

10. A cooling device according to claim 1 or 2, comprising a device (250) for setting the pressure (P) of the gas (222) in the gas space (220).

11. A cooling device according to claim 1 or 2, comprising two or more elastic separation membranes (224, 224'', 424, 424', 524, 524'), wherein the elastic separation membranes are arranged within the cooling lines (206, 406, 506) and form two or more corresponding gas spaces (220, 220'', 420, 420', 520, 520') that are separated from each other and from the liquid spaces (218, 418, 518).

12. In the cooling device according to claim 11, When viewed in cross-section of the cooling line (406, 506), the two or more gas spaces (420, 420', 520, 520') are separated from each other and from the liquid space (318, 518), and / or A cooling device in which the two or more gas spaces (220, 220'') are separated from each other and from the liquid space (218) with respect to the flow direction (R) of the coolant (112).

13. A cooling device according to claim 11, wherein the two or more gas spaces (220, 220'') are separated from each other and from the liquid space (218) with respect to the flow direction (R) of the coolant (112), and the cooling device (200) has gas (222, 222'') in each of the two or more gas spaces (220, 220''), and the gases (222, 222'') each have different pressures (P, P'').

14. A cooling device according to claim 1 or 2, comprising a foam-like and / or sponge-like element (952) having a plurality of bubbles (954) and an elastic material (956) surrounding the plurality of bubbles (954), wherein the gas space (920) is formed by the plurality of bubbles (954) of the foam-like and / or sponge-like element (952), and the separation membrane (924) is formed from the elastic material (956) surrounding the plurality of bubbles (954).

15. A cooling device (1000) for cooling a position-sensitive component (102) of a lithography apparatus (1), A cooling line (206) having a liquid space (218) for transporting coolant (112) to the position-sensitive component (102) and a gas space (220) for containing gas (222), The cooling line (206) includes an elastic separation membrane (224) which is positioned within the cooling line (206) and functions to separate the gas space (220) from the liquid space (218), A cooling device (1000) is configured such that a coolant (112) flows through the cooling lines (206, 1006, 1106) in the flow direction (R), and the diameters (D1, D1') of the cooling lines (206, 1006, 1106) taper in the flow direction (R).

16. A lithography apparatus (1), particularly an EUV lithography apparatus, comprising a cooling device (200, 1000) as described in claim 1 or 15.

17. A method for operating a cooling device (200) for cooling a position-sensitive component (102) of a lithography apparatus (1), wherein the cooling device (200) is a cooling line (206) having a liquid space (218) for transporting a coolant (112) to the position-sensitive component (102) and a gas space (220) for containing a gas (222), the cooling line (206) being a conduit with a constant cross-section in the flow direction of the coolant (112) within the cooling line (206), and an elastic separation membrane (224) disposed within the cooling line (206) that separates the gas space (220) from the liquid space (218), in the method, a) Step (S1) of flowing the coolant (112) into the liquid space (218) of the cooling line (206), b) Step (S2) to change the volume (VF1', VF2') of the liquid space (218) by deforming the elastic separation membrane (224) in response to a pressure change of the coolant (112) in the liquid space (218) and Methods that include...

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