Optical assembly, projection optics and semiconductor technology system

Abstract

The invention relates to an optical assembly (30) of a system for semiconductor technology, comprising at least one optical component (31) and at least one fastening arrangement (32) by means of which the optical component (31) can be fixed, wherein the optical component (31) has a material-bonded connection with the fastening arrangement (32) by means of an joining material (33), wherein the surface (330) of the joining material (33) exposed to the environment (40) is at least partially covered with a protective layer (34). Furthermore, the invention relates to a projection optic and a semiconductor technology system with an optical assembly according to the invention.

Description

[0001] The invention relates to an optical assembly, a projection optic and a semiconductor technology system.

[0002] Semiconductor technology systems, particularly projection exposure systems for semiconductor lithography, are subject to stringent image quality requirements to ensure the production of the desired microscopic structures with minimal defects. In a lithography or microlithography process, an illumination system uses an illumination optic to illuminate a photolithographic mask, also known as a reticle. The light passing through or reflecting from the mask is projected by a projection optic onto a substrate (e.g., a wafer) coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection optic. This projection transfers the structural elements of the mask onto the photosensitive coating of the substrate.The requirements for positioning the image on the wafer and the intensity of the light provided by the illumination system are increased with each new generation, leading to a higher load on the optical elements.

[0003] In cases of high heat load, it can be advantageous, for example, to temperature-control components, especially the optical elements designed as mirrors in EUV projection exposure systems, i.e., systems that operate with electromagnetic radiation of wavelengths between 1 nm and 120 nm, by means of fluid cooling.

[0004] Fluid-filled mirrors can also be used in DUV projection systems that operate with electromagnetic radiation with a wavelength between 100 nm and 300 nm. These mirrors typically have recesses through which liquid or gaseous fluid flows, for example, to dissipate heat from the optical surface—that is, the mirror surface exposed to the light used to image the structural elements. Particularly when using gaseous fluids such as oxygen or air, the short-wavelength electromagnetic radiation can form highly reactive radicals in combination with oxygen, posing a risk of damaging chemically sensitive surfaces in optical assemblies.

[0005] To counteract such damage to surfaces, a technical improvement for protecting exposed adhesive joints is disclosed, for example, in US patent 9,291,912 B2. This patent describes an optical system for an exposure device used in semiconductor technology, comprising an optical element held in place by a support structure at a common contact surface. Adhesive material is applied to the contact surface, bonding the optical element to the support structure.

[0006] Furthermore, a pressing device acting on the contact surface is described, which permanently presses the optical element and the support structure against each other. To seal against the environment, an O-ring seal made of rubber-elastic material is arranged around the adhesive bond at the contact surface. Other sealing materials, such as a copper seal, are also considered. The applied pressing force presses the optical element against the support structure in such a way that the O-ring ensures a fluid-tight connection between the components. However, a clamping force is always required to guarantee a reliable seal of the adhesive joint between the components. Such forces can, however, deform the optical element and impair the optical performance of the system.This means that the constant force and the resulting stress can negatively affect the system and cause undesirable drift effects in the imaging characteristics.

[0007] The object of the present invention is to provide a device which eliminates the described disadvantages of the prior art.

[0008] This problem is solved by a device having the features of independent claim 1. The dependent claims relate to advantageous further developments and variants of the invention.

[0009] An optical assembly according to the invention for a system for semiconductor technology comprises at least one optical component and at least one mounting arrangement by means of which the optical component can be fixed. The optical component has a metallurgical bond with the mounting arrangement by means of a joining material. The surface of the joining material exposed to the environment is at least partially covered with a protective layer.

[0010] A protective layer according to the invention covers at least part of the joining material or even the entire exposed surface with sufficient thickness to prevent damaging environmental influences from affecting the joining material. The protective layer must therefore be applied to the joining material to separate it from the surrounding atmosphere. In the context of the invention, "covering" includes both partial or full-surface direct contact with the exposed surface of the joining material and non-contact shielding of the exposed surface from damaging environmental influences.

[0011] Bonding materials are preferably adhesives that can be used in a variety of ways for material-bonded connections. However, alternative bonding materials, such as solders, putties, or welding materials, can also be suitable according to the invention.

[0012] Particularly in the case of fixing adhesives using oxygen or air as a rinsing or cooling medium, the radicals formed by short-wave electromagnetic radiation can be effectively prevented from reaching the surface of the fixing adhesive. Furthermore, the protective layer according to the invention can also neutralize the effects of other reactive substances that form at higher temperatures on chemically sensitive surfaces in optical assemblies.

[0013] The inventive measure makes it possible to protect the joining material from environmental influences and, for example, to prevent degradation when using adhesives. This ensures that optical components are reliably and permanently bonded to the mounting assemblies.

[0014] In an advantageous embodiment, the surface of the joining material, which is exposed to the environment, can be hermetically sealed from the environment by the sealing adhesive.

[0015] In the context of the invention, "hermetically sealed" means that no or only negligible gas or other fluid exchange from the environment of the optical component can occur at the surface of the joining material. At a minimum, the influence is limited to such a degree that, over the lifetime of the optical component, damaging gases or other substances from the environment cannot penetrate to the surface of the joining material at all, or only to such a minimal extent that, for example, when using a fixing adhesive, they cannot lead to significant degradation. Such damaging substances from the environment can originate in particular from oxygen gas, which is used, for example, as purge gas in some optical components, or from the ambient air or from moisture.

[0016] Furthermore, the joining material can advantageously be arranged in a joining gap formed between the fastening arrangement and the optical component.

[0017] In this process, a recess can be incorporated into at least one connecting surface of the optical component or the mounting arrangement. This creates a defined volume between the joining surfaces to accommodate the joining material for the connection point, whereby, particularly when using a fixing adhesive, sufficient adhesive ensures a material-bonded connection between the two joining surfaces of the two components.

[0018] The fixing adhesive in a joining gap between the optical components and the mounting arrangement can, for example, have an adhesive thickness of 0.01 mm to a maximum of 0.5 mm.

[0019] Alternatively, in a specific embodiment, a thin layer of adhesive can be arranged in the gap between the optical component and the mounting assembly such that the adhesive essentially only fills the surface roughness of the joining surfaces. This means that the adhesive gap can be less than 0.01 mm thick. The bonding surfaces are virtually in contact with each other, and the adhesive essentially only fills the surface roughness of the joining areas. A thin yet relatively large adhesive layer between the optical component and the mounting assembly allows for suitable ratios between compressive and shear stiffness.

[0020] In an advantageous embodiment, the protective layer can have non-wetting properties with respect to its contact surface.

[0021] When joining optical elements with an adhesive, the conditions at the edges are also crucial for the quality of the bond. For example, if too much adhesive is used in the bonding process between the elements to be joined, it will ooze out at the sides and be exposed to the surrounding environment. Conversely, if too little adhesive is used, the edges of the bonded area will not be optimally filled. Even with precise application, a certain amount of excess adhesive will flow beyond the bonded area, leaving some exposed surface area. The general aim is to apply slightly more adhesive than necessary to ensure a secure bond.Applying slightly too much adhesive ensures a reliable bond across the entire joining area. This exposed surface of the adhesive must then be protected from corrosion by a protective layer.

[0022] Ultimately, the wetting and flow behavior can be adjusted by modifying the viscosity during application of the protective layer, possibly also by adding appropriate additives or flow aids, and by adjusting the temperature during application. In any case, the flow behavior of the protective layer should ensure reliable, complete coverage of the exposed surface of the fixing adhesive with sufficient thickness.

[0023] Advantageously, the protective layer against the joining material can consist of a material with a lower modulus of elasticity.

[0024] The elastic modulus of the fixing adhesive used as a bonding material is greater in this case than the elastic modulus of the protective layer material. Therefore, the protective layer introduces only negligible additional stresses, if any, into the bond within the optical assembly.

[0025] In a further advantageous embodiment of the invention, the protective layer can be chemically resistant to damaging electromagnetic radiation.

[0026] Optical components in semiconductor technology are frequently exposed to high-energy radiation. For the protective coatings to function reliably over the long term, they must be chemically resistant to both direct and scattered radiation. The coating must also be permanently resistant to infrared radiation, such as heat radiation from heating devices.

[0027] In an advantageous embodiment of the invention, the protective layer can consist of a sealing adhesive.

[0028] For processing, it is advantageous that the adhesive is liquid and / or sufficiently viscous in at least one state and solid in a second state. Suitable additives allow the viscosity to be adjusted so that the sealant adhesive is easy to apply not only to large areas but also to edges. Advantageously, the susceptibility of some sealant adhesives to absorbing or releasing water is adjusted to reduce undesirable volume changes during curing.

[0029] Furthermore, the sealing adhesive can be a silicone adhesive, an epoxy resin adhesive, or a hybrid polymer STP adhesive, serving as a protective layer.

[0030] The epoxy resin-based adhesive can be, for example, a one-component or a multi-component adhesive. One-component epoxy resin-based adhesives can be heat-curing, in which case the adhesive itself or the optical assembly must be heated for the adhesive to cure. Alternatively, a UV-curing adhesive can be used, which is exposed to UV light at the application point to cure it.

[0031] Adhesives and sealants based on hybrid polymer STP are also preferred. Such materials are suitable for stress-compensating and elastic bonding, exhibiting good adhesion to various substrates. The sealant can thus reliably cover both the surface of the fixing adhesive and adjacent surfaces of the optical components, acting as a protective layer. Hybrid polymer STP adhesives can also be cured at room temperature for extended periods. The curing time can be shortened by increasing the temperature.

[0032] Advantageously, the optical component can include a device for correcting optical aberrations of a projection optic.

[0033] This type of optical component is positioned near the pupil plane of a projection optic and comprises a grid of conductive resistance structures that can be heated locally. Such devices are described in more detail, for example, in WO 2009 / 026 970 A1 of the applicant.

[0034] In an advantageous embodiment of the invention, the fastening arrangement can include an adjustment device.

[0035] For this purpose, pedestals equipped with actuators are suitable for adjusting an optical component in space. It is often necessary to adjust the optical component in several degrees of freedom, particularly up to six degrees of freedom. This includes lateral movement in three Cartesian axes and tilting movement around three axes.

[0036] In one embodiment of the invention, this can be achieved by at least one monopod that connects the optical component via a single arm as a mounting arrangement. Preferably, however, up to six monopods are provided.

[0037] Alternatively or additionally, in a further training course at least one pod can be designed as a bipod, which is supported by two arms as a mounting arrangement on a base plate and supports the optical component.

[0038] Advantageously, the material-bonded connection can be limited by a groove that is incorporated into the surface of the optical component and / or into the surface of the fastening arrangement, at least in partial sections.

[0039] A groove, at least in some sections, provided as a notch or depression, advantageously limits the flow of the fixing adhesive in a lateral direction along the component surface.

[0040] Furthermore, a circumferential groove can be suitably designed to laterally limit the adhesive flow and to collect excess adhesive.

[0041] The groove can be designed to provide sufficient volume to accommodate any remaining adhesive. Even with good wetting of the component surface by the fixing adhesive, lateral flow of the adhesive beyond the groove should be prevented. Therefore, it may be sufficient to seal the remaining adhesive within the groove with a protective layer. Low wettability of the protective layer can be advantageous, preferably extending only locally over the groove.

[0042] Another advantageous embodiment is to create a bead-like rim around the adhesive joint, at least in some sections. A bead-like rim also limits or prevents lateral flow of the adhesive. In an advantageous embodiment, the cross-section of the circumferential groove can be rectangular and have a width and / or depth of at least 3 mm.

[0043] A rectangular groove can be advantageous with regard to the spreading characteristics of the fixing adhesive if the side and base surfaces are arranged at right angles to each other.

[0044] Another aspect of the invention includes a projection optic comprising an optical assembly according to the invention for imaging an object field into an image field; it is of course also conceivable to use the invention in an illumination optic.

[0045] Another aspect of the invention includes a semiconductor technology system comprising an optical assembly according to the invention.

[0046] The invention can be particularly advantageously applied in systems for semiconductor technology, such as a projection exposure system, a mask or wafer inspection system or a mask repair system.

[0047] Exemplary embodiments and variants of the invention are explained in more detail below with reference to the drawings. They show Fig. 1. Schematic representation in meridional section of a projection exposure system for EUV projection lithography, Fig. 2 schematically in meridional section a projection exposure system for DUV projection lithography, Fig. 3 a schematic representation of the invention, and Fig. 4 a schematic representation of a further embodiment of the invention.

[0048] The following will first refer to the Fig. 1. The essential components of a projection exposure system 1 for microlithography are described as an example. The description of the basic structure of the projection exposure system 1 and its components is not intended to be restrictive.

[0049] One embodiment of a lighting system 2 of the projection exposure system 1 has, in addition to a radiation source 3, a lighting optic 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the radiation source 3 can also be provided as a separate module from the rest of the lighting system. In this case, the lighting system does not include the radiation source 3.

[0050] A reticule 7 located in the object field 5 is illuminated. The reticule 7 is held by a reticule holder 8. The reticule holder 8 can be moved, particularly in one scanning direction, via a reticule displacement drive 9.

[0051] In the Fig. Figure 1 shows a Cartesian xyz coordinate system for illustrative purposes. The x-direction runs perpendicular to the plane of the drawing. The y-direction runs horizontally, and the z-direction runs vertically. The scan direction runs in the Fig. 1 along the y-direction. The z-direction runs perpendicular to the object plane. 6.

[0052] The projection exposure system 1 comprises a projection optic 10. The projection optic 10 serves to image the object field 5 onto an image field 11 in an image plane 12. The image plane 12 is parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0053] A structure on the reticulum 7 is imaged onto a photosensitive layer of a wafer 13 located in the image plane 12 within the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be moved, particularly along the y-direction, via a wafer transfer drive 15. The movement of the reticulum 7 via the reticulum transfer drive 9 and of the wafer 13 via the wafer transfer drive 15 can be synchronized.

[0054] Radiation source 3 is an EUV radiation source. Specifically, radiation source 3 emits EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation has a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be a plasma source, for example, an LPP source (laser-produced plasma) or a DPP source (gas-discharged produced plasma). It can also be a synchrotron-based radiation source. Radiation source 3 can be a free-electron laser (FEL).

[0055] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloid reflective surfaces. The at least one reflective surface of the collector 17 can be illuminated with the illumination radiation 16 at grazing incidence (GI), i.e., with angles of incidence greater than 45° relative to the normal direction of the mirror surface, or at normal incidence (NI), i.e., with angles of incidence less than 45°. The collector 17 can be structured and / or coated to optimize its reflectivity for the useful radiation and to suppress stray light.

[0056] 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.

[0057] The illumination optics 4 comprise a deflecting mirror 19 and, downstream in the beam path, a first faceted mirror 20. The deflecting mirror 19 can be a planar deflecting mirror or, alternatively, a mirror with an effect that influences the beam beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first faceted mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field faceted mirror. The first faceted mirror 20 comprises a plurality of individual first facets 21, which are also referred to as field facets in the following. Of these facets 21, the following are in the Fig. 1 only some examples are shown.

[0058] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or semicircular border contour. The first facets 21 can be designed as planar facets or alternatively as convexly or concavely curved facets.

[0059] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 can themselves each 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.

[0060] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction.

[0061] In the beam path of the illumination optics 4, a second faceted mirror 22 is arranged downstream of the first faceted mirror 20. If the second faceted mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil faceted mirror. The second faceted 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 faceted mirror 20 and the second faceted 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 6,573,978.

[0062] 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.

[0063] The second facets 23 can also be macroscopic facets, which may, for example, have round, rectangular, or hexagonal edges, or alternatively, facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0064] The second facets 23 can have planar or alternatively convex or concave curved reflective surfaces.

[0065] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (Fly's Eye Integrator).

[0066] It can be advantageous not to arrange the second faceted mirror 22 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the pupil faceted mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0067] With the aid of the second faceted mirror 22, the individual first facets 21 are imaged into the object field 5. The second faceted mirror 22 is the last beam-shaping, or indeed the last, mirror for the illumination radiation 16 in the beam path before the object field 5.

[0068] In another embodiment of the illumination optics 4, not shown, a transmission optic can be arranged in the beam path between the second facet mirror 22 and the object field 5, which contributes in particular to imaging the first facets 21 into the object field 5. The transmission optic can have exactly one mirror, or alternatively two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optic can in particular comprise one or two mirrors for normal incidence (NI mirrors) and / or one or two mirrors for grazing incidence (GI mirrors).

[0069] The lighting optics 4, in the version shown in the Fig. Figure 1 shows exactly three mirrors after the collector 17, namely the deflecting mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

[0070] In a further embodiment of the lighting optics 4, the deflecting mirror 19 can also be omitted, so that the lighting optics 4 after the collector 17 can then have exactly two mirrors, namely the first faceted mirror 20 and the second faceted mirror 22.

[0071] The mapping of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optic into the object plane 6 is regularly only an approximate mapping.

[0072] The projection optics 10 comprise a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0073] In the Fig. In the example shown, the projection optics 10 comprise six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have an aperture for the illumination radiation 16. The projection optics 10 are a double-obscured optic. The projection optics 10 have an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0074] The reflective surfaces of the mirrors Mi can be designed as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflective surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflective surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0075] 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.

[0076] The projection optics 10 can be anamorphic. In particular, they have different magnifications βx, βy in the x and y directions. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, + / - 0.125). A positive magnification β indicates a projection without image inversion. A negative magnification β indicates a projection with image inversion.

[0077] The projection optics 10 thus lead to a reduction in the x-direction, that is, in the direction perpendicular to the scan direction, in a ratio of 4:1.

[0078] The projection optics 10 lead to a reduction of 8:1 in the y-direction, that is, in the scan direction.

[0079] Other magnification ratios are also possible. Magnification ratios with the same sign and absolute values ​​in the x and y directions, for example with absolute values ​​of 0.125 or 0.25, are also possible.

[0080] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 5 and the image field 11 can be the same or, depending on the design of the projection optics 10, different. Examples of projection optics with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0081] Each pupil facet 23 is assigned to exactly one of the field facets 21 to form an illumination channel for illuminating the object field 5. This can result, in particular, in illumination according to Köhler's principle. The far field is divided into a multitude of object fields 5 by means of the field facets 21. The field facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to each of them.

[0082] The field facets 21 are each superimposed on the reticulum 7 by an associated pupil facet 23 to illuminate the object field 5. The illumination of the object field 5 is particularly homogeneous. It preferably exhibits a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0083] The illumination of the entrance pupil of the projection optics 10 can be geometrically defined by the arrangement of the pupil facets. By selecting the illumination channels, in particular the subset of pupil facets that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting.

[0084] Another preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by a redistribution of the illumination channels.

[0085] Further aspects and details of the illumination of the object field 5 and, in particular, the entrance pupil of the projection optics 10 are described below.

[0086] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0087] The entrance pupil of the projection optics 10 cannot always be illuminated exactly by the pupil facet mirror 22. When the projection optics 10 image the center of the pupil facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found where the pairwise determined separation of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in real space. In particular, this surface exhibits a finite curvature.

[0088] The projection optics 10 may have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second faceted mirror 22 and the reticle 7. This optical element can accommodate the different positions of the tangential and sagittal entrance pupils.

[0089] During the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 1, the pupil facet mirror 22 is arranged in a plane conjugate to the entrance pupil of the projection optics 10. The field facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflecting mirror 19.

[0090] The first faceted mirror 20 is arranged at an angle to an arrangement plane defined by the second faceted mirror 22.

[0091] Fig. Figure 2 schematically shows in meridional section another projection exposure system 101 for DUV projection lithography, in which the invention can also be applied.

[0092] The design of the projection exposure system 101 and the principle of the imaging process are comparable to that in Fig. The structure and procedure described in section 1 are identical. The components are 100 times larger than the others. Fig. 1 raised reference numeral denotes the reference numerals in Fig. So, 2 starts with 101.

[0093] Unlike one such as in Fig. Due to the longer wavelength of the DUV radiation 116 used as useful light in the range of 100nm to 300nm, in particular of 193nm, refractive, diffractive and / or reflective optical elements 117, such as lenses, mirrors, prisms, planar 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 a lighting system 102, a reticule holder 108 for receiving and precisely positioning a reticule 107 provided with a structure, by which the subsequent structures on a wafer 113 are determined, a wafer holder 114 for holding, moving and precisely positioning this wafer 113 and a projection lens 110, with several optical elements 117, which are held in a lens housing 119 of the projection lens 110 via mounts 118.

[0094] The housing 119 is designed to be gas-tight, with its interior being purged with a gas under a slight overpressure.

[0095] The illumination system 102 provides DUV radiation 116 required for imaging the reticulum 107 on the wafer 113. A laser, a plasma source, or the like can be used as the source for this radiation 116. In the illumination system 102, the radiation 116 is shaped by optical elements such that, upon striking the reticulum 107, the DUV radiation 116 exhibits the desired properties with respect to diameter, polarization, wavefront shape, and the like.

[0096] The construction of the following projection optics 101 with the lens housing 119 differs in principle from that in, except for the additional use of refractive optical elements 117 such as lenses, prisms, end plates. Fig. The structure described in section 1 is therefore not described further.

[0097] Fig. Figure 3 shows a schematic representation of an optical assembly 30 according to the invention for a system for semiconductor technology. Shown are a partial view of an optical component 31 and a partial view of an associated mounting arrangement 32, which are materially bonded to each other via an joining gap in the form of an adhesive gap 35.

[0098] In the adhesive gap 35, a fixing adhesive 33, used as a bonding material, is introduced between the optical component 31 and the mounting arrangement 32. During bonding, the fixing adhesive 33, in its liquid state, can be squeezed out of the adhesive gap 35 to a certain extent in the edge regions, or ideally, it can be flush with the end face. In both cases, the fixing adhesive 33 forms an exposed surface 330 facing the surroundings 40. Reactive substances could attack such exposed surfaces.

[0099] According to the invention, the surface 330 of the fixing adhesive 33, which is exposed to the surroundings 40, is covered with a protective layer 34. In the present case, a sealing adhesive with sufficient viscosity is used as the protective layer 34. Although it spreads over the exposed surface 330 of the fixing adhesive 33, it does not run at the contact surfaces. Preferably, a sealing adhesive is used as the protective layer 34 which also exhibits low wettability with its contact surfaces. Thus, a correspondingly large contact angle of over 90° is formed at the edge regions of the protective layer 34.

[0100] Alternatively, partially wetting protective layers 34 can also be considered, provided that the material preferably covers the free surface 330 of the fixing adhesive 33 and does not spread uncontrollably beyond it.

[0101] Fig. Figure 4 shows a schematic representation of a further optical assembly 30 according to the invention for a system for semiconductor technology. In a preferred embodiment of the invention, the edge region of the fixing adhesive 33 used as joining material is limited at the end of the joining gap 35 by a circumferential groove 36 formed in the surface of the optical component 31.

[0102] The circumferential groove 36 forms a notch which limits the adhesive flow of the fixing adhesive 33 in a lateral direction along the further component surface 310 of the optical component 31 outside the joining gap 35.

[0103] Not in Fig. As shown in 4, such circumferential grooves could advantageously also be incorporated into the surface 320 of the fastening arrangement 32.

[0104] Excess fixing adhesive 33 is completely absorbed and bound in the circumferential groove 36. For this purpose, the volume of the circumferential groove 36 is designed such that it can accommodate all the extruded adhesive residue.

[0105] In the present case, it is therefore sufficient to seal the fixing adhesive 33 within the circumferential groove 36 with a protective layer 34. In particular, a low wettability of a sealing adhesive as a protective layer 34 is advantageous here. Particularly preferred sealing adhesives can be applied locally above the circumferential groove, thereby creating a hermetic seal against the environment 40. Reference symbol list 1 Projection exposure system 2 Lighting system 3. Radiation source 4 Lighting optics 5 object field 6 Object level 7 reticles 8 label holders 9 Reticle displacement drive 10 Projection optics 11 Image field 12 Image plane 13 wafers 14 wafer holders 15 wafer transfer drive 16 EUV radiation 17 Collector 18 Intermediate focus plane 19 deflecting mirrors 20 faceted mirrors 21 facets 22 faceted mirrors 23 facets 30 Optical assembly 31 Optical Component 310 Surface of the optical component 32 Mounting arrangement 320 Surface of the mounting arrangement 33 Joining material, fixing adhesive 330 Exposed surface of the fixing adhesive 34 Protective layer, sealant adhesive 35 Joining gap, adhesive gap 36 circumferential groove 40 surroundings 101 Projection exposure system 102 Lighting system 107 reticles 108 label holders 110 Projection optics 113 wafers 114 wafer holders 116 DUV radiation 117 Optical element 118 versions 119 lens bodies QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] US 9 291 912 B2

[0005] DE 10 2008 009 600 A1 [0059, 0063] US 2006 / 0132747 A1

[0061] EP 1 614 008 B1

[0061] US 6,573,978

[0061] DE 10 2017 220 586 A1

[0066] US 2018 / 0074303 A1

[0080]

Claims

[1] Optical assembly (30) of a system (1, 101) for semiconductor technology, comprising at least one optical component (31) and at least one fastening arrangement (32) by means of which the optical component (31) can be fixed, wherein the optical component (31) has a material-bonded connection with the fastening arrangement (32) by means of a joining material (33), characterized by , that the surface (330) of the joining material (33) which is exposed to the environment (40) is at least partially covered with a protective layer (34). [2] Optical assembly (30) according to claim 1, characterized by , that the surface (330) of the joining material (33) which is exposed to the environment (40) is hermetically sealed from the environment (40) by the protective layer (34). [3] Optical assembly (30) according to claim 1 or 2, characterized by, that the joining material (33) is arranged in a joining gap (35) formed between the fastening arrangement (32) and the optical component (31). [4] Optical assembly (30) according to one of claims 1 to 3, characterized by that the protective layer (34) has non-wetting properties towards a contact surface. [5] Optical assembly (30) according to any one of claims 1 to 4, characterized by , that the protective layer (34) is made of a material with a lower modulus of elasticity in relation to the joining material (33). [6] Optical assembly (30) according to any one of claims 1 to 5, characterized by , that the protective layer (34) is resistant to electromagnetic radiation. [7] Optical assembly (30) according to any one of claims 1 to 6, characterized by , that the protective layer (34) consists of a sealing adhesive. [8] Optical assembly (30) according to claim 7, characterized by, that the sealing adhesive as a protective layer (34) is a silicone adhesive or an epoxy resin adhesive or a hybrid polymer STP adhesive. [9] Optical assembly (30) according to any one of claims 1 to 8, characterized by , that the optical component (31) includes a device for correcting optical aberrations. [10] Optical assembly (30) according to any one of claims 1 to 9, characterized by , that the fastening arrangement (32) includes an adjustment device. [11] Optical assembly (30) according to any one of claims 1 to 10, characterized by , that the material-bonded connection is limited by a groove (36) that is introduced into the surface (310) of the optical component (31) and / or into the surface (320) of the fastening arrangement (32), at least in partial sections. [12] Optical assembly (30) according to claim 11, characterized by that the circumferential groove (36) is designed to accommodate excess adhesive. [13] Optical assembly (30) according to claim 11 or 12, characterized by , that the cross-section of the circumferential groove (36) is rectangular and has a width and / or depth of at least 3 mm. [14] Projection optics (10) comprising an optical assembly (30) according to any one of claims 1 to 13 for imaging an object field into an image field. [15] Semiconductor technology system (1, 101) comprising an optical assembly (30) according to any one of claims 1 to 14.

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