Device for sampling for determining a corrosion state of a module for semiconductor lithography, arrangement and method for determining a module state

Abstract

The invention relates to a device (50) for sampling for determining a corrosion state of a module (30) for semiconductor lithography, which is characterised in that the device (50) comprises a rinsing device (64) and a sample collector (56). The invention also relates to an arrangement having a device (50) for sampling a module (30) for semiconductor technology and a module (30) for semiconductor lithography, wherein the module (30) comprises a fluid channel (40) and a releasable connection element (32) for connecting a fluid line to the fluid channel (40) and wherein an interface (42) is formed between the connection element (32) and the module (30). The arrangement is characterised in that the device (50) for sampling has a rinsing device (64), wherein a sample collector (56) of the device (50), arranged downstream of the rinsing device (64) in the introduction direction, is at least partially, optionally completely, introduced into the fluid channel (40). The invention also relates to a method for determining a corrosion state of an interface (42) between a module (30) of a projection exposure system (1,101) and a connection element (32) releasably connected to the module (30), said method comprising the following steps: - sampling the interface (42), - analysing the sample (70.1) taken, - determining the state of the interface (42) based on the analysis.

Description

[0001] Device for sampling to determine a corrosion state of a module for semiconductor lithography, arrangement and method for determining a module state

[0002] This application claims priority from German patent application DE 10 2023 213 007.6, filed on December 20, 2023, the contents of which are incorporated herein by reference.

[0003] The invention relates to a device for sampling to determine the corrosion state of a module for semiconductor lithography, as well as to an arrangement comprising the device and the module. Furthermore, the invention relates to a method for determining the state of a module. In particular, the device and the method can be used for a module of a projection exposure system.

[0004] Projection exposure systems for semiconductor lithography are subject to extremely high imaging quality requirements in order to produce the desired microscopic structures with as little error as possible. In a lithography or microlithography process, an illumination system illuminates a photolithographic mask, also known as a reticle. The light passing through the mask or reflected from the mask is projected by projection optics onto a substrate (e.g., a wafer) coated with a light-sensitive layer (photoresist) and mounted in the image plane of the projection optics. This transfers the mask's structural elements to the substrate's light-sensitive coating.The requirements for positioning the image on the wafer and the intensity of the light provided by the illumination system are increasing with each new generation, resulting in a higher heat load on the optical elements.

[0005] In cases of high heat load, it can be advantageous to use water cooling to control the temperature of certain modules, such as support frames, reference frames, or optical modules, particularly in EUV projection exposure systems, i.e., systems operated with electromagnetic radiation with a wavelength between 1 nm and 120 nm, especially at 13.5 nm. Water-cooled modules can also be used in DUV projection exposure systems, i.e., systems operated with electromagnetic radiation with a wavelength between 100 nm and 300 nm. These modules comprise fluid channels through which tempered water usually flows, thereby dissipating heat from the modules. The water is prepared and supplied by a water cabinet, which is connected to the module via fluid lines.The supply and discharge lines are often connected to the fluid channels formed in the module via flanges at the interfaces to the module. The flanges are sealed against sealing surfaces formed in the module with sealing elements and can be closed for transport and / or storage of the modules. A module can have between 1 and 30 or more such interfaces, whereby the failure of just one interface, for example due to a leak, can lead to the failure of the entire module and / or the entire system. Typically, identical interfaces are used throughout the entire projection exposure system, for example, in both the illumination system and the projection optics.

[0006] The special requirements for materials in the field of EUV lithography and the resulting material pairings for the module and the flange enable or facilitate corrosion, particularly in the area of ​​the interface. In combination with the sometimes highly corrosive behavior of water, for example due to contamination, this corrosion can be further intensified over the lifetime, so that corrosion can occur at the interfaces between the flange and the sealing surface. In some cases, the corrosion can progress to the point where it undermines the sealing elements, potentially leading to leaks at the interface. Compared to use, this effect can be further exacerbated by storage of the modules, particularly under improper storage conditions.

[0007] The corrosion state in the module interface area cannot be determined in the installed state, i.e., with the flange in place. Due to the sometimes highly variable and insufficiently known conditions over the service life, the corrosion state cannot be predicted, for example, based on models. A visual inspection of the interface, during which the flange is dismantled, can result in an interface that is still tight despite corrosion remaining leaky when the flange is reinstalled. Therefore, in many cases, the visual inspection can be a destructive test.

[0008] This effect is due to the fact that the damage to the sealing surface caused by corrosion can be so advanced that the interface can no longer be adequately sealed when the flange is reinserted. The corrosion products produced during corrosion damage the sealing surfaces on the one hand, but also contribute to the seal on the other. For example, an already corroded interface may remain sealed for several months or years if left unopened, but may leak or become leaky soon after being opened and reassembled. Repairing or reworking the sealing surfaces is generally not possible for technical reasons.

[0009] This results in the disadvantage that many modules must be scrapped due to corrosion testing, even though they still have a sufficient service life. This negatively impacts the lifetime costs of the projection exposure system.

[0010] The object of the present invention is to provide a device and an arrangement that eliminates the disadvantages of the prior art described above. A further object of the present invention is to provide a method that enables the corrosion state of a module interface to be determined without disassembling the flange.

[0011] This object is achieved by a device, an arrangement, and a method having the features of the independent claims. The subclaims relate to advantageous developments and variants of the invention.

[0012] A device according to the invention for sampling to determine the corrosion state of a module for semiconductor lithography is characterized in that the device comprises a rinsing device. Furthermore, the device comprises a sample collector that receives the samples dissolved by the rinsing.

[0013] The flushing device advantageously makes it possible, on the one hand, to remove a sample from a surface of the module without damaging the surface in the process. This allows the sample to be removed from the surface with as little damage as possible. In the case of an interface that is to be examined for its corrosion state, flushing can, on the one hand, remove corrosion products while, on the other hand, leaving the corrosion system intact. The corrosion system comprises the interface and the corrosion products formed at it, some of which are firmly bonded to the interface. For example, the corrosion system has areas which, through corrosion products that have already formed, can offer the base material of the flange and / or the base body protection against advancing corrosion.This can at least slow down or even completely stop corrosion without negatively affecting the tightness of the interface.

[0014] In a first embodiment of the invention, a supply line can be arranged at one end of the flushing device. The supply line can be connected, for example, to a pump or a handheld bottle, which applies the flushing fluid to the pressure required for flushing.

[0015] In particular, the sample collector can be arranged at the other end of the device, i.e. on the side opposite the supply line.

[0016] In a further embodiment of the invention, an opening of the flushing device can be arranged between the supply line and the sample collector.

[0017] In particular, the opening of the flushing device can be directed towards the supply line. For example, the opening can be aligned at an angle to the supply line so that the flushing fluid can spray a specific surface of the module for sample collection. This angle can be in a range between 90° and 180°, preferably in a range between 120° and 160°, particularly preferably in a range between 135° and 155°. In a further embodiment, the sample collector can be designed to be elastic. This allows the outer contour of the sample collector to temporarily adapt to the cross-section of the constriction if the device has to be pushed through a constriction to the sampling site, such as a pipe or channel.The sample collector can also act as a sealing element during flushing, whereby the elastically designed sample collector can ensure uniform and complete contact between the sample collector and a surface to be sealed.

[0018] Furthermore, the sample collector can be designed with open pores. An open-pore structure allows for the absorption of fluids, such as the rinsing fluid, but also of any liquids and / or liquid samples that may be present at the sampling site. The open-pore surface also has the advantage that even solid samples adhere more easily to the open-pore surface, thus simplifying the collection of samples with the sample collector.

[0019] In addition, the sample collector can comprise a surface for receiving at least a portion of a sample. This surface can have a geometry particularly suitable for sample reception, such as a chamfer and / or a special surface that, for example, acts as an adhesive to certain samples.

[0020] In a further embodiment of the invention, the device can have a receptacle for connecting the sample collector to the device. The sample collectors can conveniently be replaced with each sampling, thus allowing for easy sample collector replacement. The device can, for example, comprise a mandrel with conical sections or other undercuts. The mandrel facilitates sliding on, and the conical sections can advantageously prevent the sample collector from accidentally slipping off, for example, when pulling the device out of a pipe or channel.

[0021] In a further embodiment, the device can have a stop for positioning the opening of the rinsing device. The stop serves to ensure good repeatability when aligning the device to a surface at the sampling location, such as an interface of a module. In particular, the stop can be adjustable, allowing one device to be used for sampling different objects.

[0022] An arrangement according to the invention comprising a device for sampling a module for semiconductor technology and a module for semiconductor lithography, wherein the module comprises a fluid channel and a detachable connecting element for connecting a fluid line to the fluid channel, and wherein an interface is formed between the connecting element and the module, is characterized in that the sampling device has a flushing device. A sample collector of the device, arranged behind the flushing device in the insertion direction, is inserted at least partially, and optionally also completely, into the fluid channel.

[0023] As explained above, the rinsing device enables samples, such as corrosion products, to be removed from the interface without causing any damage.

[0024] Furthermore, the sampling device can be inserted into the connecting element, which is designed as a flange, for example, up to a stop of the device.

[0025] In particular, the stop can define the position of the rinsing device relative to the interface. This has the advantage of ensuring that the interface can be sampled even without being visible during the device's insertion.

[0026] Furthermore, an opening of the flushing device for sampling can be positioned behind the interface in the insertion direction. This allows the interface to be sprayed directly with the flushing fluid even if it is located behind an undercut in the insertion direction.

[0027] In particular, the opening of the flushing device can be oriented toward the interface for sampling. This has the advantage that the flushing fluid sprays toward the connecting element, advantageously reducing the risk of the flushing fluid penetrating the fluid channel. This can reduce the sealing requirements of a sample collector of the device, significantly simplifying insertion and removal of the device. In a further embodiment, the device can be arranged so that it can rotate relative to the connecting element. This allows the interface to be sprayed over its entire circumference, thus ensuring the best possible sample collection.

[0028] In particular, the sample collector of the device can be designed such that, when inserted, the sample collector can seal the fluid channel toward the interior of the module against a rinsing fluid used during sampling. The sample collector thus has a dual function, with the second function being to seal the fluid channel during sample collection, thus preventing the rinsing fluid from penetrating the module's fluid channel.

[0029] In addition, the sample collector can be designed in such a way that the sample collector can collect or hold samples dissolved and / or floating in the rinsing fluid, such as corrosion products, when it is pulled out.

[0030] In further embodiments, the arrangement may comprise a device according to the embodiments described above.

[0031] A method according to the invention for determining a corrosion state of an interface between a module of a projection exposure system and a connecting element detachably connected to the module comprises the following method steps:

[0032] - Sampling of the interface.

[0033] - Analysis of the sample taken.

[0034] - Determination of the state of the interface based on the analysis.

[0035] In a first embodiment, the state of the interface can describe the lifetime of the interface. The lifetime refers, for example, to the remaining duration of safe use of the module in a projection exposure system.

[0036] Furthermore, the condition of the interface can describe its tightness. In projection exposure systems, which operate under predetermined, tight boundary conditions, tightness is an important criterion for all fluid-carrying interfaces. In the case of an EUV projection exposure system, which operates in a vacuum, a leak can lead to damage or even complete failure of the module and / or the entire projection exposure system.

[0037] In particular, the condition of the interface can describe the lifetime of the interface, which is related to its tightness. The lifetime refers to how long the interface can be assumed to remain tight under given boundary conditions.

[0038] In a further embodiment, the sampling may comprise rinsing the interface, as explained above.

[0039] Furthermore, the interface can be flushed in such a way that only loose and / or liquid and dissolved corrosion products are removed from the interface. The pressure and jet shape with which the flushing fluid hits the interface are crucial and can ensure that the corrosion system is not damaged.

[0040] Furthermore, the corrosion products dissolved in this way can be collected by a sample collector. The sample collector is designed to collect both liquid and solid corrosion products.

[0041] In another embodiment, the corrosion products can be analyzed using an EDX method. This is a well-known method and allows for precise analysis of the corrosion products present in the sample.

[0042] In particular, the condition of the interface can be determined by comparing the corrosion products present in the sample. Corrosion can be inadequately determined using a model, which can be made even more difficult by many unknown parameters. For example, the purity of the fluid used in the fluid channel may be unknown and / or the storage conditions during module storage may be completely or at least partially unknown. Non-destructive sampling, where non-destructive can refer to the tightness of the interface and the corrosion system, is an advantageous method for extending the service life of interfaces.

[0043] In the following, embodiments and variants of the invention are explained in more detail with reference to the drawings.

[0044] Figure 1 shows a meridional section of a projection exposure system for EUV projection lithography,

[0045] Figure 2 shows a meridional section of a projection exposure system for DUV projection lithography,

[0046] Figure 3 is a schematic representation of a detail of the projection exposure system,

[0047] Figure 4 is a schematic representation of the invention,

[0048] Figure 5a-c shows a schematic representation to explain the function and a method according to the invention,

[0049] Figure 6a-b further schematic representations to explain the function and a method according to the invention,

[0050] Figure 7a-b further schematic representations to explain the function and a method according to the invention, and

[0051] Figure 8 shows a flow chart of a method according to the invention.

[0052] In the following, the essential components of a projection exposure system 1 for microlithography are described by way of example with reference to Figure 1. The description of the basic structure of the projection exposure system 1 and its components is not intended to be limiting.

[0053] One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system. In this case, the illumination system does not include the light source 3.

[0054] A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9.

[0055] Figure 1 illustrates a Cartesian xyz coordinate system. The x-direction runs perpendicular to the drawing plane. The y-direction runs horizontally, and the z-direction runs vertically. The scanning direction in Figure 1 runs along the y-direction. The z-direction runs perpendicular to the object plane 6.

[0056] The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0057] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0058] The radiation source 3 is an EUV radiation source. The radiation source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation has, in particular, a wavelength in the range between 5 nm and 30 nm. The radiation source 3 can be a plasma source, for example, an LPP source (laser produced plasma) or a DPP source (gas discharged produced plasma). It can also be a synchrotron-based radiation source. The radiation source 3 can be a free-electron laser (FEL).

[0059] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (Gl), i.e., at angles of incidence greater than 45° relative to the normal direction of the mirror surface, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0060] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector 17, and the illumination optics 4.

[0061] The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which are also referred to below as field facets. Only a few of these facets 21 are shown in Fig. 1 as examples.

[0062] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

[0063] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can, in particular, be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0064] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction.

[0065] In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US Pat. No. 6,573,978.

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

[0067] The second facets 23 can also be macroscopic facets, which can, for example, be round, rectangular, or hexagonal, or alternatively facets composed of micromirrors. Reference is also made to DE 102008 009 600 A1 in this regard.

[0068] The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

[0069] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (fly's eye integrator).

[0070] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugated to a pupil plane of the projection optics 10. In particular, the pupil facet mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0071] With the help of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last beam-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path before the object field 5.

[0072] In a further embodiment of the illumination optics 4 (not shown), a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which transmission optics contributes in particular to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NL mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (GL mirrors, grazing incidence mirrors).

[0073] In the embodiment shown in Fig. 1, the illumination optics 4 has exactly three mirrors after the collector 17, namely the deflection mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

[0074] In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

[0075] The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is usually only an approximate imaging.

[0076] The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0077] In the example shown in Figure 1, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 are doubly obscured optics. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0078] Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0079] The projection optics 10 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

[0080] The projection optics 10 can, in particular, be anamorphic. It has, in particular, different image scales ßx, ßy in the x and y directions. The two image scales ßx, ßy of the projection optics 10 are preferably (ßx, ßy) = (+ / - 0.25, + / - 0.125). A positive image scale ß means an image without image inversion. A negative sign for the image scale ß means an image with image inversion.

[0081] The projection optics 10 thus leads to a reduction in the ratio 4:1 in the x-direction, i.e. in the direction perpendicular to the scanning direction.

[0082] The projection optics 10 results in a reduction of 8:1 in the y-direction, i.e. in the scanning direction.

[0083] Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions, for example, with absolute values ​​of 0.125 or 0.25, are also possible.

[0084] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 5 and the image field 11 can be the same or can be different, depending on the design of the projection optics 10. Examples of projection optics with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0085] Each of the pupil facets 23 is assigned to exactly one of the field facets 21 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the field facets 21. The field facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to them.

[0086] The field facets 21 are each imaged onto the reticle 7 by an associated pupil facet 23, superimposed on one another, to illuminate the object field 5.

[0087] The illumination of the object field 5 is, in particular, as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0088] By arranging the pupil facets, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the pupil facets that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting.

[0089] A likewise preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

[0090] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below.

[0091] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0092] The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the pupil facet mirror 22. When the projection optics 10 images the center of the pupil facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined distance of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in spatial space. In particular, this surface exhibits a finite curvature.

[0093] It is possible that the projection optics 10 have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7. With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0094] In the arrangement of the components of the illumination optics 4 shown in Figure 1, the pupil facet mirror 22 is arranged in a surface conjugated to the entrance pupil of the projection optics 10. The field facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the second facet mirror 22.

[0095] Figure 2 shows schematically in meridional section a further projection exposure system 101 for DUV projection lithography, in which the invention can also be used.

[0096] The structure of the projection exposure system 101 and the principle of imaging are comparable to the structure and procedure described in Figure 1. Identical components are designated by a reference numeral that is 100 higher than in Figure 1; thus, the reference numerals in Figure 2 begin with 101.

[0097] In contrast to an EUV projection exposure system 1 as described in Figure 1, due to the longer wavelength of the DUV radiation 116 used as useful light in the range from 100 nm to 300 nm, in particular from 193 nm, refractive, diffractive and / or reflective optical elements 117, such as lenses, mirrors, prisms, cover plates and the like, can be used in the DUV projection exposure system 101 for imaging or illumination.The projection exposure system 101 essentially comprises an illumination system 102, a reticle holder 108 for receiving and precisely positioning a reticle 107 provided with a structure, by means of which the later structures on a wafer 113 are determined, a wafer holder 114 for holding, moving and precisely positioning this wafer 113 and a projection lens 110 with a plurality of optical elements 117, which are held via mounts 118 in a lens housing 119 of the projection lens 110.

[0098] The illumination system 102 provides DUV radiation 116 required for imaging the reticle 107 on the wafer 113. A laser, a plasma source, or the like can be used as the source for this radiation 116. The radiation 116 is shaped in the illumination system 102 via optical elements such that the DUV radiation 116, upon impinging on the reticle 107, has the desired properties with regard to diameter, polarization, wavefront shape, and the like. The structure of the downstream projection optics 101 with the objective housing 119 does not differ fundamentally from the structure described in Figure 1, except for the additional use of refractive optical elements 117 such as lenses, prisms, and cover plates, and will therefore not be described further.

[0099] Figure 3 shows a schematic representation of a module 30 known from the prior art with a base body 31, wherein the base body 31 has a fluid channel 40. The module 30 can be designed as a module of a device for semiconductor lithography, such as an illumination system 2, 102 of a projection exposure system 1, 101 explained in Figures 1 and 2. The module 30 has a flange 32 as a first part of an interface 42, via which the fluid channel 40 of the base body 31 can be connected for operation via a coupling to a pipe (not shown) for supplying fluid.

[0100] The flange 32 is arranged on a support surface 33 on the base body 31 and is connected to it via screws 34. The flange 32 also has a bore 41 with a diameter corresponding to the inner diameter of the pipe.

[0101] The interface 42 further comprises a recess 35 in the base body 31, which is conical at least in sections and corresponds to the flange 32. In the embodiment shown in Figure 3, the recess further comprises a cylindrical sealing surface 36. The flange 32, in turn, comprises a pin 37 with a geometry corresponding to the recess 35, wherein an O-ring 38 for sealing the flange 32 is arranged in a recess 39 in the region of the pin 37 opposite the sealing surface 36. The recess 35 in the base body 31 merges into the fluid channel 40.

[0102] Possible corrosion of the interface 42 develops in the area between the sealing surface 36 and the opposite area of ​​the pin 37. The corrosion products caused by the corrosion (not shown) also accumulate in the area 43 at the end of the pin 37 (Figure 5a). Since this area 43 is at least accessible via the bore 41, this area 43 is preferably suitable for sampling the interface 42.

[0103] Figure 4 shows a device 50 according to the invention for sampling the interface 42, particularly in the region 43, to determine the corrosion state of the interface 42. The use of the device 50 is explained in detail in the following figures. The device 50 is designed to remove corrosion products from the interface 42, particularly in the sampling region 43 (Figure 3) between the end of the pin 37 and the recess 35.

[0104] The device 50 comprises a device support 51 formed as a half-pipe made of stainless steel or a comparable non-corrosive or low-corrosive material, which can be formed at least partially as a pipe. The inner diameter is in the range of 10 mm for Vz flanges and Flanges in the range of 4.5 mm.

[0105] The device carrier 51 has a stop 52 at one end, which defines the penetration depth of the device 50 into the flange 32 (Figure 3) or the fluid channel 40. The stop 52 is arranged at different positions on the device carrier 51 depending on the module 30 to be sampled. It is conceivable to make the stop 52 adjustable so that the device 50 can be used to sample different modules 30 or flanges 32. The stop 52 can, for example, snap into the positions corresponding to the respective modules 30.

[0106] On the side of the device carrier 51 opposite the stop, a receptacle 53 for a sample collector 56 is arranged. The receptacle 53 has a connecting element designed as a mandrel 54 and a stop designed as a plate 55, up to which the sample collector 56 is pushed onto the mandrel 54. This has the advantage that the sample collector 56 is always arranged in the same position and the sample collector 56 can be easily replaced.

[0107] The dome 54 has a tip 57 for easily sliding on the sample collector 56. Further along, the dome 54 has conical sections 58, which further facilitate sliding on the sample collector 56 and advantageously prevent or impede removal, especially accidental removal. Alternatively, the mandrel 54 can be designed as a screw dome or threaded pin to allow a sample collector 56 with an internal thread or a sample collector 56 with a through hole to be secured using a nut and washer.

[0108] The sample collector 56 is cylindrical and has bevels 59 on both sides for easier insertion and removal into and from the bore 41 in the flange 32 and the fluid channel 40. The embodiment of the sample collector 56 shown in Figure 4 comprises foam material that is, on the one hand, sufficiently elastic to be inserted through the flange 32 into the fluid channel 40 and, on the other hand, ensures sufficient tightness against a flushing fluid used during sampling. Furthermore, the flushing fluid and any corrosion products present can be easily absorbed by the foam material of the sample collector 56 and conveyed out through the bore 41 of the flange 32.

[0109] The device 50 further comprises a flushing device 64, which comprises a supply line designed as a laboratory hose 60, hereinafter referred to as hose 60, with an inner diameter of 2 mm and an outer diameter of 3 mm. This is guided in the device carrier 51 up to or just before the plate 55 of the receptacle 53 and connected to the device carrier 51 (not shown). The flushing device 64 further comprises a deflection 61 with an angle of 140° at the end of the hose 60. The direction 63 of an opening 62 of the deflection 61 is directed, with the device 50 inserted up to the stop 52, towards the area 43 of the interface 42 (Figure 3; Figure 5c). This ensures that the flushing device 64 directly sprays the area 43 of the interface 42 where the corrosion products, if present, are expected to occur.

[0110] At the other end of the hose 60, for example, a handheld bottle or a connection to a pump can be connected, with which the rinsing fluid can be introduced into the device 50. The following Figures 5a-5c, Figures 6a, 6b, and Figures 7a, 7b describe the three phases of sampling the interface 42.

[0111] Figures 5a to 5c describe the insertion of the device 50 through the bore 41 in the flange 32 into the fluid channel 40. The stop 52 ensures that the opening 62 of the flushing device 64 is directed towards the area 43 of the interface 42 in which possible corrosion products 70 are deposited and / or accumulated.

[0112] Figure 5a shows the state shortly before insertion of the device 50, in which the chamfer 59 of the sample collector 56 rests on the edge of the bore 41 of the flange 32.

[0113] Figure 5b shows the state in which the sample collector 56, made of elastic foam, is compressed and inserted through the bore 41 in the flange 32. The foam is preferably a foam suitable for sampling, which meets the requirements regarding outgassing and material composition in semiconductor lithography, particularly in EUV semiconductor lithography. Furthermore, the foam is tear-resistant, so that the detachment of foam parts during sampling can be avoided.

[0114] Figure 5c shows the state in which the device 50 is inserted into the flange 32 up to the stop 52. The direction 63 of the opening 62 points toward the area 43 in which the corrosion products 70 to be sampled are located. In this state, the sample collector 56 seals the fluid channel 40 against the flushing fluid 71 (Figure 6a).

[0115] Figures 6a and 6b show the actual sampling process, during which the corrosion products 70 are removed from the area 43 using a rinsing fluid 71. Hard tools, such as hooks or scrapers, such as those used by dentists, are deliberately avoided. This ensures that the "corrosion system" is not disturbed as much as possible and that acceleration or accelerated progression of corrosion due to mechanical damage and / or exposure of surfaces after sampling is excluded. The corrosion system has, for example, areas which, through already formed corrosion products, offer the base material of the flange 32 or the base body 31 protection from advancing corrosion. The corrosion can thus be at least slowed down or even completely stopped without compromising the tightness of the interface 42.

[0116] Figure 6a shows the start of flushing with the flushing fluid 71, which, as explained above, is sprayed against the area 43 containing the corrosion products 70 by a pump or by squeezing a handheld bottle with sufficient pressure. The pressure is designed such that the washing out or dissolution of already loose corrosion products 70.1 is ensured, but detachment or mechanical damage to the solid corrosion products 70 is avoided. The corrosion system thus remains intact during sampling.

[0117] Figure 6b shows a state during flushing, in which the device 50 is rotated in the bore 41 of the flange 32 so that the entire circumference of the area 43 is flushed with the flushing fluid 71. Some detached corrosion products 70.1 can also be seen floating and / or dissolved in the flushing fluid 71.

[0118] The flushing fluid 71 contains alcohol, such as ethanol. Alcohol is inert with respect to the corrosion process, so even if residues remain, it has no negative impact on the corrosion, such as accelerating it. Furthermore, alcohol evaporates quickly and combines well with any water still present in the fluid channel 40.

[0119] The sample collector 56 absorbs any residual water that may be present in the fluid channel 40 as well as the rinsing fluid 71.

[0120] Figures 7a and 7b show the removal of the sample through the bore 41 in the flange 32. The sample contains the corrosion products 70.1 floating and / or dissolved by the flushing fluid 71.

[0121] Figure 7a shows the state immediately after flushing the area 43 with the flushing fluid 71 collected in the fluid channel 40 and the flushed-out corrosion products 70.1. Figure 7b shows the withdrawal of the device 50, during which the sample collector 56 is again compressed. The foam is designed such that, despite the compression, the flushing fluid 71 can be completely absorbed by the sample collector 56. The corrosion products 70.1 remain on the porous surface of the sample collector 56 and are removed from the flange 32 with this sample collector 56. The already dissolved corrosion products 70.1 remaining in the fluid channel 40 upon withdrawal can be subsequently removed or removed by flushing the fluid channel 40 if the interface 42 is assessed positively. Figure 8 describes a possible method that enables the determination of the corrosion state of the interface 42 of the module 30.

[0122] In a first method step 81, the interface 42 of the module 30 is sampled. In a second method step 82, the sample 70 taken is analyzed.

[0123] In a third method step 83, the state of the interface 42 is determined on the basis of the analysis.

[0124] List of reference symbols

[0125] 1 projection exposure system

[0126] 2 Lighting system

[0127] 3 Radiation source

[0128] 4 Lighting optics

[0129] 5 Object field

[0130] 6 Object level

[0131] 7 reticles

[0132] 8 reticle holders

[0133] 9 Reticle displacement drive

[0134] 10 Projection optics

[0135] 11 Image field

[0136] 12 Image plane

[0137] 13 wafers

[0138] 14 wafer holders

[0139] 15 Wafer relocation drive

[0140] 16 EUV radiation

[0141] 17 Collector

[0142] 18 Intermediate focal plane

[0143] 19 Deflecting mirrors

[0144] 20 facet mirrors

[0145] 21 facets

[0146] 22 facet mirrors

[0147] 23 facets

[0148] 30 Module

[0149] 31 Basic body module

[0150] 32 flange

[0151] 33 contact surface

[0152] 34 screws

[0153] 35 Recess base body sealing surfaces base body

[0154] Pin flange

[0155] O-ring

[0156] O-ring recess

[0157] Fluid channel

[0158] Flange bore

[0159] interface

[0160] Sampling area (sampling area)

[0161] device

[0162] Fixture carrier

[0163] stop

[0164] Recording

[0165] Cathedral

[0166] Sign

[0167] Sample collector

[0168] Pointed conical sections

[0169] Chamfers

[0170] Laboratory hose

[0171] redirection

[0172] Opening deflection

[0173] Towards opening

[0174] Flushing device ,70.1 Corrosion products

[0175] Flushing fluid

[0176] Process step 1

[0177] Process step 2

[0178] Process step 3 1 Projection exposure system 2 Illumination system 7 Reticle 108 Reticle holder

[0179] 110 Projection optics

[0180] 113 wafers

[0181] 114 wafer holders

[0182] 116 DUV radiation

[0183] 117 optical element

[0184] 118 versions

[0185] 119 lens housings

[0186] M1-M6 mirrors

Claims

Patent claims 1 . Device (50) for sampling for determining a corrosion state of a module (30) for semiconductor lithography, characterized in that the device (50) comprises a rinsing device (64) and a sample collector (56), wherein the sample collector (56) comprises a surface for receiving at least a portion of a sample (70, 70.1).

2. Device (50) according to claim 1, characterized in that a supply line (60) is arranged at one end of the flushing device (64).

3. Device (50) according to claim 2, characterized in that the sample collector (56) is arranged at the other end of the device (50).

4. Device (50) according to one of claims 2 or 3, characterized in that an opening (62) of the flushing device (64) is arranged between the supply line (60) and the sample collector (56).

5. Device (50) according to claim 4, characterized in that the opening (62) of the flushing device (64) is directed in the direction of the supply line (60).

6. Device (50) according to one of claims 1 to 5, characterized in that the sample collector (56) is elastic and / or open-pored.

7. Device (50) according to one of claims 1 to 6, characterized in that the device (50) has a receptacle (53) for connecting the sample collector (56) to the device (50).

8. Device (50) according to one of claims 4 to 7, characterized in that the device (50) has a stop (52) for positioning the opening (62) of the flushing device (64).

9. Arrangement with a device (50) for sampling a module (30) for semiconductor technology and a module (30) for semiconductor lithography, wherein the module (30) comprises a fluid channel (40) and a detachable connecting element (32) for connecting a fluid line to the fluid channel (40) and wherein an interface (42) is formed between the connecting element (32) and the module (30), characterized in that the device (50) for sampling has a rinsing device (64), wherein a sample collector (56) of the device (50), arranged behind the rinsing device (64) in the insertion direction, is at least partially inserted into the fluid channel (40).

10. Arrangement according to claim 9, characterized in that the device (50) for sampling is inserted into the connecting element (32) up to a stop (52) of the device (50), and wherein the stop (52) defines the position of the rinsing device (64) relative to the interface (42).

11. Arrangement according to one of claims 9 or 10, characterized in that an opening (62) of the rinsing device (64) for sampling in the inserted state is arranged behind the interface (42) in the insertion direction.

12. Arrangement according to claim 11, characterized in that the opening (62) of the rinsing device (64) for sampling is aligned in the direction of the interface (42).

13. Arrangement according to one of claims 9 to 12, characterized in that the device (50) is arranged rotatably relative to the connecting element (32).

14. Arrangement according to one of claims 9 to 13, characterized in that the sample collector (56) is designed such that, in the inserted state, it seals the fluid channel (40) in the direction of the module interior against a rinsing fluid (71) used during sampling.

15. Arrangement according to one of claims 9 to 14, characterized in that the sample collector (56) is designed such that it receives samples (70.1) dissolved and / or floating in a rinsing fluid (71) when it is pulled out.

16. Arrangement with a device (50) according to one of claims 1 to 8.

17. A method for determining a corrosion state of an interface (42) between a module (30) of a projection exposure system (1, 101) and a connecting element (32) detachably connected to the module (30), comprising the following method steps: - sampling the interface (42), wherein the sampling of the interface comprises taking a sample from the interface. - Analysis of the sample taken (70.1 ), - Determination of the state of the interface (42) based on the analysis.

18. Method according to claim 17, characterized in that the state of the interface (42) determines a service life and / or a tightness the interface (42).

19. Method according to one of claims 17 or 18, characterized in that the state of the interface (42) describes a service life of the interface (42) related to the tightness of the interface (42).

20. Method according to one of claims 17 to 19, characterized in that the sampling comprises rinsing the interface (42).

21. Method according to claim 20, characterized in that the flushing of the interface (42) is carried out in such a way that it only removes already loose and / or liquid and dissolved corrosion products (70.1) from the interface (42).

22. Method according to claim 21, characterized in that the corrosion products (70.1) are collected by a sample collector (56).

23. Method according to one of claims 21 or 22, characterized in that the corrosion products (70.1) are analyzed using an EDX method.

24. Method according to one of claims 17 to 23, characterized in that the determination of the condition of the interface (42) is based on a comparison of the corrosion products (70.1) present in the sample and corrosion products (70,70.1) determined during visual inspections of the interface (42) and the visual condition of the interface (42).

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