Flow straighteners for semiconductor technology systems

Abstract

The invention relates to a flow straightener (200), in particular for semiconductor technology systems, a method for inserting such a flow straightener (200) into a fluid channel (26), in particular of a semiconductor technology system, and a correspondingly equipped semiconductor technology system. The flow straightener (200) for calming turbulent flow with guide surfaces (202) extending in a direction parallel to a longitudinal axis (201), which are arranged such that in the use state they divide a total flow cross-section (204) of the flow straightener (200) perpendicular to the longitudinal axis (201) into at least four flow channels (205), is reversibly compressible in the radial direction such that the extension perpendicular to the longitudinal axis (201) in the compressed state is smaller than that of the total flow cross-section (204) in the use state.

Description

[0001] The invention relates to a flow straightener, in particular for semiconductor technology systems, a method for inserting such a flow straightener into a fluid channel, in particular of a semiconductor technology system, and a correspondingly equipped semiconductor technology system.

[0002] In the state of the art, semiconductor technology systems refer to systems used to manufacture or test microstructured devices or the components required for them. An example of such a system is a projection exposure system for photolithography.

[0003] Photolithography is used to manufacture microstructured components, such as integrated circuits. The projection exposure system used in this process comprises an illumination system and a projection system. The image of a mask (also called a reticle) illuminated by the illumination system is projected in a reduced size onto a substrate coated with a light-sensitive layer and arranged in the image plane of the projection system, for example, a silicon wafer, by means of the projection system in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0004] Both in illumination systems and in projection systems, in particular in projection exposure systems designed for the EUV range, i.e. for exposure wavelengths from 5 nm to 30 nm, several optical elements, in particular mirrors, are usually provided in order to achieve the desired imaging of the mask onto the substrate. Due to the required accuracy, it must be ensured, especially in projection systems, that the position of the individual optical elements in relation to one another and to the mask and the substrate changes only within extremely small tolerances - if at all - during operation of the projection exposure system. The shape of the optical elements, in particular the mirror surfaces, must also not change or only change within a predetermined framework. Any change in the position and / or shape of one or more optical elements can lead to a reduction in the imaging quality of the projection system.

[0005] Corresponding changes in the position and / or shape of one or more optical elements can occur due to heat input into the optical elements or into the structure supporting the optical elements. Such heat input inevitably occurs, for example, due to the absorption of illumination radiation by the optical elements, the absorption of interfering radiation, particularly in the infrared range, and the heat loss from electrical components in the projection system. Electrical actuators are known to compensate for changes in the position of the optical elements to a certain extent, but these actuators themselves also emit heat.To avoid or at least minimize changes in the shape of the optical elements from a desired shape and to dissipate heat introduced into the projection exposure system, in particular its projection system, it is known to provide at least some of the optical elements and / or other components of the projection exposure system and in particular of the projection system with fluid channels for conducting a temperature control fluid—in particular, demineralized water. The fluid channels, particularly in optical elements, are generally integrated directly into the structure of the optical elements, frequently in the form of channel-shaped openings that run internally within the structure of the optical element.

[0006] Even if the temperature of the individual components can be well regulated by passing a temperature control fluid through parts of the projection exposure system, so that changes in the position and / or shape of one or more optical elements due to heat input can be reduced or even completely avoided, it has been shown that passing temperature control fluid through the fluid channels provided for this purpose introduces vibrations into the components of the projection exposure system, which can lead to a reduction in image quality, particularly if they occur in the projection system.

[0007] The causes of these vibrations introduced by the tempering liquid include flow-induced vibrations (FIV), which result from the interaction of a turbulent flow with the wall of the fluid channel.

[0008] To reduce such flow-induced vibrations, it is known that the cross-section and course of the fluid channel can be optimized to minimize turbulence. Such optimization generally results in larger cross-sections and the smallest possible curvatures of the fluid channel. However, larger cross-sections in particular promote waterline acoustics (WLA), which also contribute to unwanted vibrations. Vibrations from mechanical machines, such as a circulation pump, propagate through the temperature control fluid along the line, similar to sound in the air.

[0009] Even if it may be possible to reduce the total vibrations introduced by the passage of temperature control fluid to a global minimum, in which the sum of FIV and WLA vibrations is minimal, by appropriately selecting the cross-section and other design of the fluid channels, the resulting vibrations can still reduce the image quality of a projection exposure system beyond a permissible level.

[0010] The object of the present invention is to provide an alternative or additional possibility for reducing the vibrations generated by a flowing liquid, such as a temperature control medium, in particular in a semiconductor technology system, such as a projection exposure system.

[0011] This object is achieved by a device according to claim 1 and the associated method for installing the device according to claim 9, as well as a correspondingly equipped semiconductor technology system according to claim 13. Advantageous further developments are the subject of the dependent claims.

[0012] Accordingly, the invention relates to a flow straightener, in particular for semiconductor technology systems, for calming turbulent flow with guide surfaces extending in a direction parallel to a longitudinal axis, which are arranged such that in the use state they divide a total flow cross-section of the flow straightener perpendicular to the longitudinal axis into at least two flow channels, wherein the flow straightener is reversibly compressible in the radial direction such that the extension perpendicular to the longitudinal axis in the compressed state is smaller than that of the total flow cross-section in the use state.

[0013] Furthermore, the invention relates to a method for installing a flow straightener according to one of the preceding claims in a fluid channel, wherein in order to achieve a frictional connection, the total flow cross-section of the flow straightener in the use state is larger than the cross-section of the fluid channel, comprising the steps: - Inserting and positioning the flow straightener in the compressed state at a previously determined desired location in the fluid channel; and - Decompress the positioned flow straightener so that it connects force-fittingly to the wall of the fluid channel.

[0014] The invention also relates to a semiconductor technology system comprising at least one fluid channel for a temperature control medium, wherein at least one flow straightener according to the invention is arranged in the fluid channel, which flow straightener is preferably installed with a flow straightener according to the invention.

[0015] The invention has recognized that the vibrations occurring in systems in the semiconductor industry due to the flow of temperature control fluid, in particular flow-induced vibrations, can basically be reduced by flow straighteners in the fluid channel.

[0016] Flow straighteners are generally considered to be well-known in the state of the art. Flow straighteners are known, for example, as intermediate pieces or inserts for piping systems, particularly in ventilation systems to reduce noise, but also in water pipes, for example, to reduce measurement errors caused by turbulent flow. To provide such flow straighteners, they are installed at suitable locations directly during the construction of the piping system, inserted into existing pipes by temporarily cutting open an existing piping system, or they replace a previously removed section of pipe.

[0017] Due to the special circumstances of semiconductor technology systems, flow straighteners directly comparable to the state of the art cannot generally be used. For example, when creating one or more flow channels, for example, using an optical element in a semiconductor technology system, it is often not yet certain at which point along which fluid channel turbulence will actually occur, requiring calming by a flow straightener. Therefore, it is generally not possible to effectively position a flow straightener in the fluid channel immediately upon creation of at least one fluid channel.

[0018] If a fluid channel is created, for example, by an optical element of a semiconductor technology system, suitable tests can be used to determine whether and to what extent temperature control fluid flowing through the fluid channel actually generates disturbing vibrations and - if so - at which point along the fluid channel a flow straightener should be arranged.

[0019] However, unlike state-of-the-art piping systems, the fluid channel in optical elements of semiconductor technology systems cannot usually be opened at the location where a flow straightener is desired in order to provide a flow straightener directly adapted to the cross-section of the fluid channel at the desired location.

[0020] The flow straightener according to the invention, which in its state of use functions fundamentally similarly to a flow straightener known from the prior art in that it has guide surfaces extending in a direction parallel to a longitudinal axis to calm turbulent flow. These guide surfaces are arranged such that in the state of use they divide a total flow cross-section of the flow straightener (i.e. the maximum flow cross-section that can be covered by the flow straightener) perpendicular to the longitudinal axis into at least two - usually significantly more - flow channels, is characterized by being reversibly compressible in the radial direction. By temporarily reducing the radial expansion, the flow straightener can in many cases be moved through the fluid channel itself to the desired location, e.g., by being pushed along the fluid channel using a suitable wire.Once the compressed flow straightener has reached the desired location in the fluid channel, it is decompressed, i.e., the previous compression is reversed. If the flow straightener, in its decompressed state, has a larger cross-section or overall flow cross-section than the fluid channel, the flow straightener can be positioned and secured at the desired location due to the frictional connection between the flow straightener and the wall of the fluid channel.

[0021] Even if the flow straightener according to the invention has been described above primarily in connection with semiconductor technology systems, for which flow straighteners known from the prior art are not or only hardly suitable, the flow straightener according to the invention can also be used in any other applications in which a flow straightener is to be arranged in a fluid channel, in particular also in piping systems.

[0022] The flow straightener according to the invention is not only suitable for reducing turbulence, even if this is primarily addressed below. Thus, a flow straightener according to the invention can also reduce pressure gradients that may occur transversely to the flow direction due to deflections of the temperature control fluid. The guide surfaces extending parallel to the longitudinal axis reduce the volume in which a pressure gradient can develop transversely to the flow direction, which ultimately reduces the overall pressure differences across the cross-section.

[0023] It is preferred if the reversibility of the compression of the flow straightener is achieved by using a shape memory alloy at least as a material component of the flow straightener, wherein the shape memory alloy is preferably pseudoplastically deformed for compression in order to achieve a one-time reversibility through a one-way effect of the shape memory alloy. If the flow straightener is made partially or entirely of shape memory alloy, the completely decompressed state of the flow straightener can be the shape that the shape memory alloy "remembers."

[0024] In principle, a shape memory alloy can be used to enable a two-way effect, whereby the fully decompressed state should then occur at all expected idle and operating temperatures, while the compressed state should exist at a temperature significantly below the expected idle and operating temperatures (i.e., the temperatures that the flow straightener can expect to reach during operation, but also during non-operational periods). In such a case, the flow straightener can be compressed by rapid cooling and then passed through a fluid channel in this state. Once the desired location has been reached, the flow straightener only needs to be heated to the idle temperature so that it is fully decompressed. The flow straightener then maintains this state even at the temperatures encountered during operation.

[0025] However, it is preferred if the shape memory alloy is pseudoplastically deformed for compression in order to achieve a one-time reversibility through a one-way effect of the shape memory alloy. In other words, the shape memory alloy should be designed such that, starting from a compressed state and reaching a fully decompressed state through sufficient heating, this state is generally retained even upon subsequent cooling. With such a shape memory alloy, the flow straightener can preferably be compressed at room temperature (at least 19°C to 22°C), although heating to significantly higher temperatures (particularly above 50°C) is required for the shape memory alloy to return to its "remembered" shape.

[0026] As an alternative to using a shape memory alloy, the reversibility of compression can be achieved through the elasticity of at least one material component of the flow straightener, with a removable clamp element preferably being provided to temporarily maintain the compressed state. In other words, the flow straightener should be capable of compression by utilizing elastic deformability. This compressed state can be maintained, for example, by a suitable clamp element, with the clamp element being able to be removed from the flow straightener at the desired location in a fluid channel, whereby the flow straightener then assumes its original, uncompressed shape.

[0027] The clamping element may be a rope-like element wound around the flow straightener in the compressed state or a sleeve element at least partially accommodating the flow straightener in the compressed state.

[0028] A “rope-like element” is an element which, in the sense of solid body statics, in particular rope statics, can essentially be regarded as a pliable rope. It is therefore an element which can practically only absorb tensile forces. The term is not restricted to ropes in the narrow sense, but also includes rope-like structures such as chains and metal or plastic wires. If the rope-like element is wound around the compressed flow straightener and kept under sufficient tension, it can hold the flow straightener in the compressed state until the rope-like element is loosened. The rope-like element can be loosened, among other things, by cutting it, which can also be done away from the flow straightener if the rope-like element is guided in the form of a loop.As a rule, in such a case the rope-like element can also be completely removed by pulling on at least one of the ends of the rope-like element created by the separation.

[0029] If a sleeve element is provided which at least partially accommodates the flow straightener in the compressed state, the flow straightener can expand into its decompressed state after the sleeve element has been withdrawn. In order to be able to withdraw the sleeve element, a holding force must generally be applied, at least temporarily, to the flow straightener, which is still compressed at that time. It is possible, for example, for the holding force in question to be applied by a piston or pin extendable from the base of the sleeve element along the longitudinal axis of the sleeve element. The piston or pin can practically push the flow straightener out of the sleeve element or - namely with corresponding relative movement of the sleeve element - the sleeve element is withdrawn from the flow straightener, which then remains stationary.

[0030] Preferably, the guide surfaces are arranged such that, in use, they divide the total flow cross-section of the flow straightener perpendicular to the longitudinal axis into at least four, preferably at least nine, flow channels. Such a minimum number of flow channels generally results in a stable structure of the flow straightener in the decompressed state. However, the number of flow channels can also be significantly greater.

[0031] It is preferred if flow channels that are at least completely delimited by guide surfaces have a substantially rectangular or honeycomb-shaped cross-section. A corresponding shape of the flow channels when the flow straightener is in use enables good flow straightening and calming of fluid flowing through the flow straightener. It is preferred if the individual guide surfaces have a pre-deformation, e.g. a bend, which facilitates the buckling of the individual guide surfaces when the flow straightener is compressed. This also ensures that a guide plate buckles uniformly over its entire length and that there is no change in the buckling mode along a guide plate that could potentially limit the compressibility of the flow straightener.A corresponding pre-deformation can be so small that a rectangular or honeycomb-shaped cross-section can still be assumed for the flow channels.

[0032] Preferably, at least one end face of the flow straightener is non-planar, i.e. the edges of the guide vanes forming the end face of the flow straightener do not lie in a common plane, for example perpendicular to the longitudinal axis. Rather, some of the edges in question protrude further from the flow straightener than others. The envelope on a corresponding end face can in particular have a protruding tip from which an edge-free surface extends. In the case of a flow straightener with a substantially circular cross-section, a corresponding end face can therefore be conical. Such a design can improve the flow to the flow straightener and in particular reduce additional vibrations that may occur due to the flow.

[0033] Preferably, the end faces of the individual guide surfaces on at least one side of the flow straightener can have a shape that favors the flow direction and can, for example, be rounded. This can also improve the flow direction of the flow straightener.

[0034] To explain the method according to the invention, by which the previously described flow straightener is inserted into a fluid channel, reference is first made to the above explanations. In order for the flow straightener to remain permanently at the desired location in the fluid channel, the total flow cross-section must be larger than the cross-section of the fluid channel at this location, thus establishing a force-fit connection between the flow straightener and the wall of the fluid channel as soon as the flow straightener is decompressed.

[0035] To insert the flow straightener in the compressed state, it can be inserted into the fluid channel at an easily accessible location and then pushed to the desired location along the fluid channel, e.g., using a wire or similar device. Once the desired location is reached, the flow straightener can be decompressed, whereupon it adheres forcefully to the wall of the fluid channel.

[0036] If the flow straightener comprises a shape memory alloy, the temperature of the flow straightener and / or the surrounding area can be increased to decompress the flow straightener. For this purpose, a sufficiently heated fluid can be passed through the fluid channel, for example.

[0037] If the flow straightener is held in the compressed state by a clamp element, this clamp element must be removed to decompress the flow straightener.

[0038] It is preferred if the fluid channel in which the flow straightener is to be installed is a fluid channel for a temperature control medium through an optical element, preferably a mirror, of a system for semiconductor technology, preferably a projection exposure system, more preferably an EUV projection exposure system.

[0039] For an explanation of the system according to the invention for semiconductor technology, reference is made to the above explanations.

[0040] The invention will now be described by way of example using advantageous embodiments with reference to the accompanying drawings. In the drawings: Fig. 1: a schematic representation of a projection exposure system for photolithography; Fig. 2: a detailed section of the Fig. 1; Fig. 3a, b: a schematic representation of a first embodiment of a flow straightener according to the invention; Fig. 4a-d: a schematic representation of a method according to the invention for installing the flow straightener from Fig. 2 into the projection exposure system according to Fig. 1; Fig. 5a, b: a schematic representation of a second embodiment of a flow straightener according to the invention; Fig. 6a, b: a schematic representation of a third embodiment of a flow straightener according to the invention; Fig. 7: a first embodiment variant of the embodiments according to Fig. 3, Fig. 5 and Fig. 6; Fig. 8: a first embodiment variant of the embodiments according to Fig. 3, Fig. 5 and Fig. 6; and Fig. 9a-e: schematic representation of exemplary cross sections of further flow straighteners according to the invention.

[0041] In Fig. Figure 1 shows a schematic meridional section of a projection exposure system 1 for photolithography as an example of a system for semiconductor technology. The projection exposure system 1 comprises an illumination system 10 and a projection system 20.

[0042] With the aid of the illumination system 10, an object field 11 is illuminated in an object plane or reticle plane 12. The illumination system 10 comprises an exposure radiation source 13, which, in the illustrated embodiment, emits illumination radiation at least comprising useful light in the EUV range, i.e., in particular, with a wavelength between 5 nm and 30 nm. The exposure radiation source 13 can be a plasma source, for example an LPP source (laser produced plasma) or a DPP source (gas discharge produced plasma). It can also be a synchrotron-based radiation source. The exposure radiation source 13 can also be a free-electron laser (FEL).

[0043] The illumination radiation emanating from the exposure radiation source 13 is first focused in a collector 14. The collector 14 can be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 14 can be exposed to the illumination radiation at grazing incidence (GI), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 14 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0044] After the collector 14, the illumination radiation propagates through an intermediate focus in an intermediate focal plane 15. If the illumination system 10 is constructed in a modular design, the intermediate focal plane 15 can generally be used for the - also structural - separation of the illumination system 10 into a radiation source module, comprising the exposure radiation source 13 and the collector 14, and the illumination optics 16 described below. With such a separation, the radiation source module and illumination optics 16 then together form a modular illumination system 10.

[0045] The illumination optics 16 comprises a deflecting mirror 17. The deflecting mirror 17 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 17 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation from stray light of a different wavelength.

[0046] The deflecting mirror 17 deflects the radiation originating from the exposure radiation source 13 onto a first facet mirror 18. If the first facet mirror 18 is arranged—as in the present case—in a plane of the illumination optics 16 that is optically conjugated to the reticle plane 12 as the field plane, it is also referred to as a field facet mirror.

[0047] The first facet mirror 18 comprises a plurality of micromirrors 18', each of which can be individually pivoted about two mutually perpendicular axes, for the controllable formation of facets. Each micromirror 18' is preferably equipped with an orientation sensor (not shown) for determining the orientation of the micromirror 18'. The first facet mirror 18 is thus a microelectromechanical system (MEMS system), as described, for example, in DE 10 2008 009 600 A1.

[0048] In the beam path of the illumination optics 16, a second facet mirror 19 is arranged downstream of the first facet mirror 18, resulting in a double-faceted system whose basic principle is also referred to as a honeycomb condenser (fly's eye integrator). If the second facet mirror 19—as in the illustrated embodiment—is arranged in a pupil plane of the illumination optics 16, it is also referred to as a pupil facet mirror. However, the second facet mirror 19 can also be arranged at a distance from a pupil plane of the illumination optics 16, whereby the combination of the first and second facet mirrors 18, 19 results in a specular reflector, as described, for example, in US 2006 / 0132747 A1, EP 1 614 008 B1, and US 6,573,978.

[0049] The second facet mirror 19 does not necessarily have to be constructed from pivotable micromirrors, but can instead comprise individual facets formed from one or a manageable number of mirrors that are significantly larger than micromirrors, which are either fixed or can only be tilted between two defined end positions. However, as shown, it is also possible to provide the second facet mirror 19 with a microelectromechanical system comprising a plurality of micromirrors 19' that can each be individually pivoted about two mutually perpendicular axes, each preferably comprising an orientation sensor.

[0050] With the help of the second facet mirror 19, the individual facets of the first facet mirror 18 are imaged into the object field 11, which is usually only an approximate image. The second facet mirror 19 can be the last beam-forming mirror or actually the last mirror for the illumination radiation in the beam path before the object field 11.

[0051] Each facet of the second facet mirror 19 is assigned to exactly one of the facets of the first facet mirror 18 to form an illumination channel for illuminating the object field 11. This can, in particular, result in illumination according to the Köhler principle.

[0052] The facets of the first facet mirror 18 are each imaged by an associated facet of the second facet mirror 19, superimposed on one another, to illuminate the object field 11. The illumination of the object field 11 is as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0053] By selecting the illumination channels ultimately used, which is easily possible by appropriately adjusting the micromirrors 18' of the first facet mirror 18, the intensity distribution in the entrance pupil of the projection system 20 described below can also be adjusted. This intensity distribution is also referred to as the illumination setting. It may also be advantageous not to arrange the second facet mirror 19 exactly in a plane that is optically conjugated to a pupil plane of the projection system 20. In particular, the pupil facet mirror 19 can be arranged tilted relative to a pupil plane of the projection system 20, as described, for example, in DE 10 2017 220 586 A1.

[0054] At the Fig. However, in the arrangement of the components of the illumination optics 16 shown in Figure 1, the second facet mirror 19 is arranged in a surface conjugated to the entrance pupil of the projection system 20. Deflecting mirror 17 and the two facet mirrors 18, 19 are arranged tilted both relative to the object plane 12 and relative to each other.

[0055] In an alternative, not shown embodiment of the illumination optics 16, a transmission optics comprising one or more mirrors can be provided in the beam path between the second facet mirror 19 and the object field 11. The transmission optics can, in particular, comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (GI mirrors, grazing incidence mirrors). With an additional transmission optics, in particular, different positions of the entrance pupil for the tangential and for the sagittal beam path of the projection system 20 described below can be taken into account.

[0056] Alternatively, it is possible that the Fig. 1 is dispensed with, for which purpose the facet mirrors 18, 19 are then to be suitably arranged opposite the radiation source 13 and the collector 14.

[0057] With the help of the projection system 20, the object field 11 in the reticle plane 12 is transferred to the image field 21 in the image plane 22.

[0058] The projection system 20 comprises a plurality of mirrors M i , which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0059] In the Fig. In the example shown in Figure 1, the projection system 20 comprises six mirrors M 1 to M 6 . Alternatives with four, eight, ten, twelve or any other number of mirrors M i are also possible. The penultimate mirror M 5 and the last mirror M 6Each has a passage opening for the illumination radiation, which means that the projection system 20 shown is a double-obscured optic. The projection system 20 has an image-side numerical aperture that is greater than 0.3 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0060] The reflection surfaces of the mirrors M i can be designed as free-form surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors M i but can also be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. The mirrors M i Just like the mirrors of the illumination optics 16, they can have highly reflective coatings for the illumination radiation. These reflective coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0061] The projection system 20 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 11 and a y-coordinate of the center of the image field 21. This object-image offset in the y-direction can be approximately as large as a z-distance between the object plane 12 and the image plane 22.

[0062] The projection system 20 can in particular be anamorphic, ie it has in particular different image scales β x , β y in the x- and y-direction. The two magnifications β x , β y of the projection system 20 are preferably at (β x , β y) = (+ / - 0.25, / +- 0.125). A magnification ratio β of 0.25 corresponds to a reduction in the ratio 4:1, while a magnification ratio β of 0.125 results in a reduction in the ratio 8:1. A positive sign for the magnification ratio β means an image without image inversion, a negative sign means an image with image inversion.

[0063] Other magnifications are also possible, including identical and absolutely identical magnifications β x , β y in x and y directions are possible.

[0064] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 11 and the image field 21 can be the same or different, depending on the design of the projection system 20. Examples of projection systems 20 with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0065] The projection system 20 may, in particular, have a homocentric entrance pupil. This may be accessible. However, it may also be inaccessible.

[0066] A reticle 30 (also called a mask) arranged in the object field 11 is illuminated by the illumination system 10 and transferred to the image plane 21 by the projection system 20. The reticle 30 is held by a reticle holder 31. The reticle holder 31 can be displaced, in particular in a scanning direction, via a reticle displacement drive 32. In the illustrated embodiment, the scanning direction runs in the y-direction.

[0067] The reticle 30 may have an aspect ratio between 1:1 and 1:3, preferably between 1:1 and 1:2, more preferably 1:1 or 1:2. The reticle 30 may be substantially rectangular in shape and is preferably 5 to 7 inches (12.70 to 17.78 cm) long and wide, more preferably 6 inches (15.24 cm) long and wide. Alternatively, the reticle 30 may be 5 to 7 inches (12.70 to 17.78 cm) long and 10 to 14 inches (25.40 to 35.56 cm) wide, and is preferably 6 inches (15.24 cm) long and 12 inches (30.48 cm) wide.

[0068] A structure on the reticle 30 is imaged onto a light-sensitive layer of a wafer 35 arranged in the region of the image field 21 in the image plane 22. The wafer 35 is held by a wafer holder 36. The wafer holder 36 can be displaced, in particular along the y-direction, via a wafer displacement drive 37. The displacement of the reticle 30, on the one hand, via the reticle displacement drive 32, and the wafer 35, on the other hand, via the wafer displacement drive 37, can be synchronized with each other.

[0069] The Fig. The projection exposure apparatus 1 shown in Figure 1 or its projection system 20, the above description of which essentially reflects known prior art, is characterized in that a temperature control system 100 is provided, with which various components of the projection system 20 can be kept at a desired temperature, regardless of whether changes in the position and / or shape of the mirrors M 1 to M 6to be avoided or at least kept as low as possible.

[0070] In Fig. 1 and Fig. 2, which is merely an enlargement of part of the Fig. 1, for reasons of clarity, the temperature control system 100 is on the mirror M 4 limited and only shown very schematically. As indicated by the dotted additional inlets and outlets, the temperature control system 100 can also be equipped with additional mirrors M 1 , M 2 , M 3 , M 5 and / or M 6 as well as other components not shown, such as in particular the supporting structure to which the mirrors M 1 to M 6 are attached. It is also possible for the temperature control system 100 to temperature control components of the exposure system 10. However, the exposure system 10 can also have its own temperature control system.

[0071] The temperature control system 100 comprises fluid lines 101 for conveying a temperature control medium, a circulation pump 102 for conveying the temperature control medium through the fluid lines 101, and a controllable heat / cold source as an element 103 for actively controlling the temperature of the temperature control medium. The fluid lines 101 are connected to a mirror M to be tempered. 4 through-flowing fluid channel 26, resulting in a closed temperature control circuit 105 for the temperature control medium.

[0072] The circulation pump 102 supplies the tempering medium, which can be controlled to a desired temperature using the active tempering element 103, to or through various components, such as the mirror M 4, where heat exchange occurs, so that the corresponding components approach the actively controlled temperature of the temperature control medium over time. This is widely known in the prior art.

[0073] The element 103 for active temperature control of the temperature control medium can be provided as a heat pump with an electrically operated heating element, which is designed to supply or extract heat from the temperature control medium flowing through a heat exchanger.

[0074] To prevent vibrations of the circulation pump 102 and / or the active temperature control element 103 from being transmitted through the structure, the circulation pump 102 and / or the active temperature control element 103 are generally mechanically decoupled from the projection system 10 as much as possible and arranged away from it. For this reason, the circulation pump 102 and / or the active temperature control element 103 are generally arranged outside the evacuatable space provided for the optical elements of the projection exposure system 1. The system boundary between the evacuatable space and the area with ambient conditions is defined in Fig. 1 and Fig. 2 indicated by the dashed line 90.

[0075] In addition to the illustrated elements 101, 102, 103, the temperature control system 100 may also include other elements, such as controllable valves. If the temperature control system 100 is used to flow temperature control medium through several components of the projection exposure system 1 in different parallel temperature control circuits 105, valves can be used to individually adjust the flow rate in the individual temperature control circuits 105.

[0076] All elements 101, 102, 103 of the temperature control system 100, but also the fluid channels 26 through components of the projection exposure system 1, are designed to generate as few flow-induced vibrations as possible and to have line acoustics advantageously designed to dampen acoustic vibrations in the temperature control medium resulting from this or from other reasons.

[0077] Despite these efforts, it is possible that disturbing vibration-generating turbulences, especially in the area of ​​fluid channels 26 in mirrors M 1 to M 6 occur, which can be determined by suitable tests in which tempering medium is passed through the fluid channels 26 at flow rates intended for later operation. If corresponding disruptive turbulence is detected, a flow straightener 200 according to the invention can be provided.

[0078] In Fig. 3 shows an embodiment of a flow straightener 200 according to the invention, wherein Fig. 3a shows the flow straightener 200 in a fully decompressed state, while the flow straightener 200 in Fig. 3b is fully compressed.

[0079] The flow straightener 200 comprises a plurality of guide surfaces 202 extending parallel to the longitudinal axis 201, with which the total flow cross-section 204 resulting at the end face 203 is divided into a plurality of honeycomb-shaped flow channels 205. The structure of the flow straightener 200, as shown in Fig. 3a is not dissimilar to that of flow straighteners known from the prior art.

[0080] However, the flow straightener 200 according to the invention or its guide surfaces 202 are made of a deformable material, so that the flow straightener 200 can be reversibly compressed in the radial direction. The flow straightener 200 in the compressed state is in Fig. 3b. As can be seen from the enlargement in Fig. 3b, all guide surfaces 202, which are essentially flat in the decompressed state, bulge during compression (cf. Fig. 2a) into a wave shape, so that as a result the radial expansion of the flow straightener 200 can be reduced to approximately half of the original expansion by compression.

[0081] As explained below in connection with Fig. 5 and Fig. 6, the deformation of the guide plates 202 can only be elastic. Fig. However, in the embodiment shown in Figure 3, the guide surfaces 202 are made entirely of shape memory alloy, which undergoes pseudoplastic deformation for compression. Consequently, the flow straightener 200 retains its compressed shape after compression (see Figure 3). Fig. 3b) until it is heated to a sufficiently high temperature that it decompresses again due to a one-way effect of the shape memory alloy, i.e. the Fig. 3a and retains it permanently - even when cooled down again.

[0082] In Fig. 4a-d shows an example of how the flow straightener 200 is arranged in a fluid channel 26 in a mirror M 4 (of whose structure in Fig. 4 only the part immediately adjacent to the fluid channel 26 is shown) of the projection exposure system 1 can be used or installed.

[0083] Before starting the method presented here, a location 26' is identified in the fluid channel 26 at which a flow straightener 200 is to be arranged. The location 26' in question can be determined by suitable tests in which the flow behavior of a temperature control medium in the fluid channel 26 is investigated.

[0084] At a location (not shown) remote from the location 26', at which the fluid channel 26 is easily openable, such as a connection point of the fluid channel 26 in the mirror M 4 to a fluid line 101 (cf. Fig. 3), a flow straightener 200 according to Fig. 3 in its compressed state (cf. Fig. 3b) and pushed along the fluid channel 26 to the desired location 26' using a push wire 250 ( Fig. 4b).

[0085] Once the flow straightener 200 has reached the desired location 26', a liquid is flowed through the fluid channel 26 in the direction indicated by the arrow 90, which liquid is sufficiently warm to activate the memory effect of the shape memory alloy, whereby the flow straightener 200 again assumes its - in Fig. 3a - takes on a decompressed form ( Fig. 4c). To prevent the flow straightener 200 from moving away from the location 26' during the decompression process due to the fluid flow around it, the push wire 250 remains attached to the flow straightener 200 until the decompression is completely completed.

[0086] Once the flow straightener 200 is fully decompressed, it rests force-fittingly against the wall of the fluid channel 26, since its total flow cross-section 204 is larger than the cross-section of the fluid channel 26, thereby permanently fixing it at the location 26'. The fluid used to decompress the flow straightener 200 can then be drained, and the push wire 205 can be removed ( Fig. 4d).

[0087] The fluid channel 26 can then be integrated into a temperature control circuit 105 by connecting it to fluid lines 101. The flow straightener 200 installed in the fluid channel 26 ensures that any turbulence that may occur at point 26' in the fluid flowing through the fluid channel 26, in particular the temperature control medium, is avoided or that an already existing turbulent flow is calmed.

[0088] In Fig. 5 and Fig. 6, further embodiments of a flow straightener 200 according to the invention are shown schematically. Since these flow straighteners 200 and their guide plates 204 are fundamentally comparable to the embodiment according to Fig. 3, for details, please refer to the above illustration and the accompanying explanations; in Fig. 5 and Fig. 6 is a schematic sectional view through the fluid channel 26 (see also Fig. 4) and the flow straightener 200 are sufficient.

[0089] In contrast to the embodiment according to Fig. 3 are in the embodiments according to Fig. 5 and Fig. 6 the flow straighteners 200 or their guide plates 202 are not made of shape memory material, but of a material which can be compressed (cf. Fig. 3b) can be deformed purely elastically. In order to keep the flow straightener 200 in the compressed state and to decompress it again only at the desired location 26' in a fluid channel 26, a clamp element 300 (cf. Fig. 5 and Fig. 6) should be provided.

[0090] In the embodiment according to Fig. 5, the clamp element 300 is designed as a sleeve element 310 which at least partially receives the flow straightener 200 in the compressed state and which is attached to the free end of a pressure-resistant sleeve 311, with which the sleeve element 310 and a flow straightener 200 inserted therein can be pushed along a fluid channel 26 to a desired location 26' ( Fig. 5a). Inside the sleeve element 310, a piston 312 is provided, which can be actuated by a wire 313 guided in the sleeve 311, similar to a Bowden cable.

[0091] To decompress and thus install the flow straightener 200 at the desired location 26', the sleeve element 310 is pulled over the pressure-resistant sleeve 311 in the direction away from the flow straightener 200, while the piston 312 is moved relative to the sleeve element 310 due to the corresponding movement of the wire 313 such that the piston 312 remains stationary relative to the fluid channel 26. Through such a movement sequence, the sleeve element 310 is pulled away from the compressed flow straightener 200 without the flow straightener 200 moving away from the desired location 26'.

[0092] At the latest when the sleeve element 310 is completely removed from the flow straightener 200, whereby the clamp element 300 is considered to be removed, the flow straightener 200 decompresses due to the elastic deformation to achieve the compressed state ( Fig. 5b). The flow straightener 200 then rests forcefully against the wall of the fluid channel 26 and is thus held at the location 26'.

[0093] In the embodiment according to Fig. 6, the clamp element 300 is a rope-like element 320 wound around the flow straightener 200 in the compressed state; in the illustrated embodiment, it is a plastic wire. The rope-like element 320 is guided in a loop, with the two free ends 321 of the element 320 being guided through a pressure-resistant sheath 322 and held there under tensile stress ( Fig. 6a).

[0094] The flow straightener 200 can be pushed in the compressed state to the desired location 26' in the fluid channel 26 using the pressure-resistant sleeve 322, as previously described. If one of the two free ends 321 of the element 320 is now released, the flow straightener 200 relaxes at the desired location 26' ( Fig. 6b). Once the flow straightener 200 is completely decompressed, the rope-like element 320 can be completely pulled away from the flow straightener 200 and out of the fluid channel 26 by pulling on the other of the two free ends 321. To prevent an unintentional change in the position of the flow straightener 200 in the flow channel 26, the pressure-resistant sleeve 322 is used to counteract the withdrawal of the rope-like element 320. Once the rope-like element 320 is completely removed, the pressure-resistant sleeve 322 can also be removed.

[0095] In Fig. 7 shows a variant embodiment which relates to any embodiments, in particular to any of the embodiments shown according to Fig. 3, Fig. 5 or Fig. 6, can be applied.

[0096] In the Fig. In the flow straightener 200 shown in the decompressed state in Figure 7, one end face 203 of the flow straightener 200 is non-planar. The end face 203 in question is conical, with the end edges of the guide surfaces 202 arranged in an edge-free, namely conical surface 211, starting from a central tip 210. This allows for a favorable flow to the flow straightener 200.

[0097] The design variant according to Fig. 8 can be applied to any embodiments, as well as the embodiments according to Fig. 3, Fig. 5 and Fig. 6. In this embodiment, the edges of the individual guide surfaces 202 are rounded on at least one end face 203 of the flow straightener 200 and thus have a shape that is favorable for the flow. Fig. 8 is limited to the representation of the relevant area of ​​a single guide surface 202 of the flow straightener 200.

[0098] In Fig. 9 schematically shows cross sections of alternative embodiments of flow straighteners 200.

[0099] In the embodiment according to Fig. 9a, the flow straightener 200 is essentially tubular, with the inner region of the circumferential tubular part 206 of the flow straightener 200 being divided into two flow channels 205 by a single guide surface 202. If the flow straightener 200 rests fully against the inner wall of a flow channel (not shown), this is also divided into two flow channels 205.

[0100] The flow straightener 200 in Fig. 9b has a substantially identical cross-section to the embodiment of Fig. 9a. However, the circumferential tubular part 206 of the flow straightener 200 is slotted lengthwise here, which improves the compressibility of the flow straightener 200.

[0101] For the flow straightener 200 according to Fig. 9c, the circumferential tubular part 206 of the flow straightener 200 is different from the embodiments in Fig. 9a and Fig. 9b, allowing the flow straightener 200 to be compressed to an even smaller cross-section. However, the remaining tubular parts 206 are sufficiently dimensioned to provide sufficient stability to the circumferential tubular part 206 of the flow straightener 200 in the decompressed state and in contact with the wall of a fluid channel 26.

[0102] In the embodiments according to Fig. 9d and Fig. 9e, two or more guide surfaces 202 are provided, each of which runs perpendicular to one another, whereby the flow straightener 200 is given sufficient stability in the decompressed state and in contact with the wall of a fluid channel 26. In the embodiment according to Fig. 9d, four separate flow channels 205 are formed, in the embodiment according to Fig. 9e nine separate flow channels 205 were created. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2008 009 600 A1

[0047] US 2006 / 0132747 A1

[0048] EP 1 614 008 B1

[0048] US 6,573,978

[0048] DE 10 2017 220 586 A1

[0053] US 2018 / 0074303 A1

[0064]

Claims

[1] Flow straightener (200), in particular for semiconductor technology systems, for calming turbulent flow, having guide surfaces (202) extending in a direction parallel to a longitudinal axis (201) and arranged such that, in the state of use, they divide a total flow cross-section (204) of the flow straightener (200) perpendicular to the longitudinal axis (201) into at least two flow channels (205), characterized by that the flow straightener (200) is reversibly compressible in the radial direction such that the extension perpendicular to the longitudinal axis (201) in the compressed state is smaller than that of the total flow cross-section (204) in the use state. [2] Flow straightener according to claim 1, characterized bythat the reversibility of the compression is achieved by using a shape memory alloy at least as a material component of the flow straightener (200), wherein for compression the shape memory alloy is preferably pseudoplastically deformed in order to achieve a one-time reversibility by a one-way effect of the shape memory alloy. [3] Flow straightener according to claim 1, characterized by that the reversibility of the compression is achieved by elasticity of at least one material component of the flow straightener (200), wherein a removable clamp element (300) is preferably provided for temporarily maintaining the compressed state. [4] Flow straightener according to claim 3, characterized bythat the clamp element (300) is a rope-like element (320) wound around the flow straightener (200) in the compressed state or a sleeve element (310) at least partially receiving the flow straightener (200) in the compressed state. [5] Flow straightener according to one of the preceding claims, characterized by that the guide surfaces (202) are arranged such that, in the state of use, they divide the total flow cross-section (204) of the flow straightener (200) perpendicular to the longitudinal axis (201) into at least four, preferably at least nine flow channels (205). [6] Flow straightener according to one of the preceding claims, characterized by that flow channels (205) which are at least completely delimited by guide surfaces (202) have a rectangular or honeycomb-shaped cross-section. [7] Flow straightener according to one of the preceding claims, characterized bythat at least one end face (203) of the flow straightener (200) is non-planar, wherein the envelope on the end face (203) in question preferably forms an edge-free surface (211) around a protruding tip (210). [8] Flow straightener according to one of the preceding claims, characterized by that the edges of the individual guide surfaces (202) on at least one end face (203) of the flow straightener (200) have a shape which is favorable for the flow, and are preferably rounded. [9] Method for installing a flow straightener (200) according to one of the preceding claims in a fluid channel (26), wherein in order to achieve a frictional connection, the total flow cross-section (204) of the flow straightener (200) in the use state is larger than the cross-section of the fluid channel (26), comprising the steps: - introducing and positioning the flow straightener (200) in the compressed state at a previously determined desired location (26') in the fluid channel (26); and - Decompressing the positioned flow straightener (200) so that it fits snugly against the wall of the fluid channel (26). [10] Method according to claim 9, characterized by that in order to decompress the flow straightener (200), the temperature of the flow straightener (200) and / or the surroundings of the flow straightener (200) is increased. [11] Method according to claim 9, characterized by that an existing clamp element (300) is removed to decompress the flow straightener (200). [12] Method according to one of claims 9 to 11, characterized by that the fluid channel (26) is a tempering channel through an optical element, preferably a mirror (M 1 , M 2 , M 3 , M 4 , M 5 , M 6), a system for semiconductor technology, preferably a projection exposure system (1), further preferably an EUV projection exposure system. [13] System for semiconductor technology comprising at least one fluid channel (26) for a temperature control medium, characterized by that at least one flow straightener (200) according to one of claims 1 to 8 is arranged in the fluid channel (26), which flow straightener was preferably installed using a method according to one of claims 9 to 12. [14] Plant according to claim 13, characterized by that the fluid channel (26) is guided through an optical element of the system for semiconductor technology and at least one flow straightener (200) is arranged in the part of the fluid channel (26) guided through the optical element. [15] Installation according to claim 13 or 14, characterized by that the system is a projection exposure system (1) for photolithography.

Images