Method for protecting an adhesive layer from stray radiation, optical component and semiconductor technology installation

Abstract

The invention relates to a method for protecting an adhesive layer (20) on an optical component (11), in particular on an optical component (11) for wavefront deformation, from stray radiation (22), in particular from stray radiation (22) in the UV wavelength range. The method involves protecting the adhesive layer (20) from the stray radiation (22) by introducing internal engraving (23) into a material of the optical component (11) and / or protecting the adhesive layer (20) from the stray radiation (22) by applying at least one protective layer (24) onto at least one surface (19a) of the optical component (11) not covered by the adhesive layer (20). The invention also relates to an optical component (11) and a semiconductor technology installation.

Description

[0001] Method for protecting an adhesive layer from scattered radiation, optical component and semiconductor technology system

[0002] Reference to related application

[0003] This application claims priority from German patent application DE102023213188.9 filed on December 21, 2023, the entire disclosure of which is incorporated by reference into this application.

[0004] Background of the invention

[0005] The invention relates to a method for protecting an adhesive layer on an optical component, in particular on an optical component for wavefront deformation, from scattered radiation, in particular from scattered radiation in the UV wavelength range. The invention also relates to an optical component, in particular for wavefront deformation, comprising an adhesive layer, as well as to a semiconductor technology system comprising at least one such optical component.

[0006] Optical components in the form of individual optical elements, e.g. in the form of lenses, or in the form of more complex assemblies, are often attached to a holder by means of an adhesive, more precisely by means of an adhesive layer applied to a lateral surface of the optical component. It is known that the adhesive of the adhesive layer is attacked by scattered radiation, particularly in an environment containing air or oxygen, and degrades over the lifetime of the optical component. This is particularly the case when the scattered radiation is radiation in the UV wavelength range, i.e. at wavelengths between 100 nm and 380 nm. In this case, both the adhesive surface and the adhesive strength typically decrease during long-term operation of the optical component. This can lead to the load-bearing capacity of the adhesive bond being exceeded due to the dead weight of the optical component.External stress, e.g. during transport or replacement work, can also cause the adhesive bond to be accidentally released and the optical component to fall down.

[0007] US Pat. No. 6,097,536 describes an assembly comprising a holder and a transparent component that transmits UV radiation in the UV wavelength range and adheres to the holder with the aid of an adhesive. The adhesive can be curable using UV radiation with a predetermined spectral distribution. A layer is applied to the transparent component in the area of ​​the adhesive. This layer transmits UV radiation in a spectral range suitable for curing the adhesive and highly reflects and / or absorbs UV radiation in a useful spectral range within the spectral range transmitted by the transparent component.

[0008] Object of the invention

[0009] The object of the invention is to provide a method, an optical component and a system in semiconductor technology that effectively protect an adhesive layer from scattered radiation.

[0010] Subject of the invention

[0011] This object is achieved by a method of the type mentioned at the outset, comprising: protecting the adhesive layer from scattered radiation by introducing an internal engraving into a material of the optical component and / or protecting the adhesive layer from scattered radiation by applying at least one protective layer to at least one surface of the optical component not covered by the adhesive layer.

[0012] In the process described here, the adhesive layer is protected from scattered radiation, which, without the protection provided by the internal engraving and / or the protective layer, would propagate through the material of the optical component and reach the adhesive layer. As described above, this could result in the degradation of the adhesive layer or adhesive and, in the worst case, the adhesive bond between the optical component and a component to which the optical component is attached being released.

[0013] The scattered radiation from which the adhesive layer is to be protected can, in particular—but not necessarily—be scattered radiation in the UV wavelength range, i.e., radiation at wavelengths between 100 nm and 380 nm. Scattered radiation is usually a portion of the useful radiation that passes through the optical component. Therefore, if the scattered radiation is UV radiation, the useful radiation is typically also UV radiation.

[0014] A protective layer that is virtually impermeable to scattered radiation in the UV wavelength range because it absorbs, reflects, and / or scatters the scattered radiation can be produced cost-effectively, as such protective layers can be applied using known and thus robust manufacturing processes, see, for example, the aforementioned US Pat. No. 6,097,536, which is incorporated by reference in its entirety into this application. Furthermore, scattered light simulations can be easily performed to characterize the protective effect of the protective layer.

[0015] Internal engraving in the material of the optical component is typically achieved using laser engraving. Laser engraving, also known as sub-surface laser engraving (SSLE), allows virtually any three-dimensional structure to be created in a material that is transparent to the laser radiation used for engraving. SSLE is an established process that can be implemented with minimal effort and high precision. Internal glass engraving is a process that intervenes only at the component level, requires less effort than a system modification, and does not require any corresponding qualification.

[0016] The optical component can comprise one or more optical components. The internal engraving is incorporated into at least one of the optical components. The material of the optical component or of the at least one optical component into which the internal engraving is incorporated is typically a glass material, for example quartz glass, but it can also be diamond, sapphire, PMMA, etc. (see the Wikipedia article "Glasinnengravur", "https: / / de.wikipedia.org / wiki / Glasinnengravur"). The internal engraving is typically created using a laser beam that is focused at different positions within the material. At the focus positions, the energy density of the typically pulsed laser beam is so high that the glass is thermally destroyed at the respective position, e.g., through cracking, melting, or evaporation, creating an image point or a point-like area of ​​the internal engraving.By deflecting the focused laser beam within the material, a desired three-dimensional structure of the internal engraving can be created with high precision. The internal engraving usually creates an air pocket at a particular image point, or the glass crystallizes, thereby changing the refractive index within the material. The internal engraving can therefore be used to redirect scattered radiation, i.e., typically to reflect and / or scatter it, in order to protect the adhesive layer from the scattered radiation. The image points in the material that together form the internal engraving are typically on the order of a micrometer or smaller and can sometimes be seen in the material with the naked eye.

[0017] While the creation of scattered light structures on the surfaces of optical fibers or the introduction of internal engravings into glass materials is generally known, it is typically used to create representations, e.g., in the form of symbols or characters, as described, for example, in DE10336352B4. DE102016201072A1 describes that marker areas created by laser engraving can be used to position at least two correction elements relative to each other. A material-removing process can also be used to create markings for measuring facet elements, see, for example, DE102013220473A1.

[0018] In a further embodiment, when the internal engraving is introduced into the material of the optical component, at least one preferably planar structure is created for deflecting, in particular for reflecting and / or scattering, the scattered radiation. As described above, the internal engraving can have almost any three-dimensional geometry. To protect the adhesive layer from scattered radiation, it is advantageous if the internal engraving has one or more structures at which the scattered radiation is reflected or scattered. The structures of the internal engraving are spaced apart from the adhesive layer in the material of the optical component. In the material, the structures can protect or shield essentially the entire surface area of ​​the component covered by the adhesive layer from scattered radiation. These are preferably planar structures that have a thickness that is generally on the order of micrometers.The planar structures can, for example, be convex or concave, although this is not absolutely necessary, i.e. the planar structures can basically have any geometric shape. It is generally advantageous if the material of the optical component has two or more planar structures that run at different distances from the adhesive layer in order to protect the adhesive layer as effectively as possible from scattered radiation that may pass through the material in different directions. In addition to or alternatively to one or more planar structures, the internal engraving can also have one or more three-dimensional structures that are considerably thicker than the planar structures. Using a scattered light simulation, an optimized structure oroptimized structures of the internal engraving are determined, which redirect as much scattered radiation as possible, which would reach the adhesive layer without the internal engraving, into non-critical areas.

[0019] The application of the protective layer can be combined with the creation of the internal engraving in order to minimize the stress on the adhesive layer caused by scattered radiation.

[0020] In one variant, the adhesive layer is protected from scattered radiation by the internal engraving and by the protective layer, wherein the internal engraving at least partially deflects the scattered radiation towards the protective layer, in particular reflects and / or scatters it towards the protective layer. In this case, the internal engraving has a geometry selected such that scattered radiation reaching the internal engraving is at least partially deflected towards the protective layer. This is possible, for example, if the internal engraving is located between the protective layer and the adhesive layer and the scattered radiation enters the material of the optical component laterally between the protective layer and the internal engraving. In this case, the scattered radiation entering laterally can be deflected towards the protective layer at the internal engraving, for example at a flat structure of the internal engraving. In this way, the adhesive layer can be protected particularly efficiently from scattered radiation.

[0021] In a further variant, the optical component comprises two preferably plate-shaped optical elements, between which at least one spacer is arranged. The internal engraving is incorporated into the material of the spacer and / or the protective layer is applied to a surface of the spacer not covered by the adhesive layer. In this variant, the optical component or assembly can be used for wavefront deformation, but this is not mandatory.

[0022] The two optical elements can, for example, be plate-shaped optical elements in the form of flat plates, which are also referred to below as optical plates, but they can also be other optical elements, e.g. lenses or the like. The two optical elements are held at a constant distance from one another by the spacer or several spacers. The material of the spacer is typically a glass material, for example quartz glass. It is advantageous if the material of the optical elements matches the material of the spacer. The two optical elements and also the spacer are transparent to the useful radiation - and thus also to the scattered radiation - whose wavelength is typically in the UV wavelength range.

[0023] As a rule, the optical component has at least two spacers which laterally delimit a space or gap between the two optical plates. An air, gas or liquid flow can be guided through the space between the two optical elements, which can be used for cooling, for example. The adhesive layer is typically applied to a surface of the spacer which faces away from the space and which usually runs essentially perpendicular to the optical elements. The adhesive layer is typically used to fasten the optical component or the spacer to a holder. The holder can be designed for low-vibration mounting of the optical component in a semiconductor technology system. The holder can be designed, for example, in the manner of a bipod or the like.The adhesive layer is typically applied to only one surface area of ​​the spacer, where it is connected to a respective holder. It is possible for the optical component to be attached to the surface of the spacer facing away from the gap, using multiple holders that are offset from one another in the longitudinal direction of the two optical elements. The internal engraving can, if necessary, be incorporated into the material of the spacer, limited to a volume area in or around the respective holder, but it is also possible for the internal engraving to extend over the entire length of the spacer.

[0024] In a further variant, the protective layer is applied to a surface of the spacer facing away from the adhesive layer, which preferably delimits a gap between the two optical elements. The beam path of the useful radiation runs through the two optical elements and the gap. The at least one spacer is arranged outside the beam path of the useful radiation and is therefore essentially only hit by scattered radiation that spreads in the gap and within the optical plates. If the protective layer is applied to the surface that laterally delimits the gap, the scattered radiation that penetrates the spacer via the gap can be effectively blocked. In this way, the UV exposure to the adhesive layer can be reduced and the service life of the optical component can be increased.The protective layer is typically designed to absorb the scattered radiation and subsequently dissipate it as heat. The space between the two optical elements is typically purged, for example, by means of a gas or air purge, so that the resulting heat can be directly dissipated at the protective layer and keeps the spacer at a constant temperature. The production of radiation, especially UV-absorbing protective layers, is generally known and is therefore not described in detail in the present application.

[0025] It is advantageous if the protective layer extends over the entire length of the surface of the spacer that laterally delimits the gap. However, it is also possible for the protective layer to be limited in the longitudinal direction of the spacer essentially to at least one area where the adhesive layer is connected to the holder or holders. The protective layer on the surface that laterally delimits the gap is not subjected to mechanical stress, so that no damage to the protective layer is to be expected over the course of the service life of the optical component. Also, there are no adhesive areas on the surface that laterally delimits the gap to connect the spacer to the optical plates (see below), so that these cannot be impaired and no new qualification of the optical component is required.

[0026] In a further development, the spacer is connected to a respective optical element via an adhesive connection, which preferably has a plurality of adhesive areas. Preferably, when the internal engraving is introduced, at least one preferably planar structure is created for deflecting, in particular for reflecting and / or scattering, radiation, in particular UV radiation, which enters the spacer at gaps between the adhesive areas when the adhesive areas cure. The spacer is typically connected to a respective optical element via an adhesive connection. The adhesive connection can be applied over a large area, but it is also possible for the adhesive connection to have a plurality of adhesive areas or adhesive points that are laterally spaced from one another, such that gaps exist between the adhesive areas.The radiation used to cure the adhesive areas, or more precisely the adhesive of the adhesive areas, which is typically UV radiation, is generally irradiated essentially perpendicularly from the outside onto the interface between the spacer and the respective optical element. With this type of irradiation, the protective layer, which may be applied to the surface delimiting the gap, does not prevent the adhesive areas from curing. Typically, the entire interface is irradiated homogeneously for curing. With homogeneous irradiation, the radiation used for curing can penetrate the spacer material at the gaps between the adhesive areas. The flat structure(s) can prevent the radiation entering the spacer at the interface to the first optical element from reaching the second optical element and possibly producing unwanted or harmful radiation there.The adhesive areas at the interface with the second optical element partially cure in an uncontrolled manner. Redirecting the radiation entering the spacer at the planar structure(s) back to the adhesive areas can also be advantageous to enable homogeneous curing of the adhesive areas. A suitably optimized internal engraving can therefore be beneficial not only for protecting the adhesive layer at which the spacer is connected to the holder, but also for the adhesive bond between the respective optical element and the spacer.

[0027] In a further variant, at least one of the optical elements has a plurality of temperature-controlled, in particular heatable, zones in order to generate a wavefront deformation. In this variant, a respective optical element typically has a thermal manipulator, which can, for example, have a plurality of electrically conductive and ohmic structures for heating the local zones, as described, for example, in DE102020201723A1, which is incorporated by reference in its entirety into the content of this application. The local zones can typically be separately temperature-controlled or heated and are arranged in an optically effective manner in the beam path of the useful radiation. The local zones can, for example, be arranged in a grid arrangement, but this is not absolutely necessary.A respective thermal manipulator of the optical element typically also has an actuating device for adjusting a temperature profile of the respective optical element.

[0028] The optical elements can be formed, for example, as thin plates of quartz glass, which have a thickness on the order of approximately 10 mm. In quartz glass, a temperature increase at wavelengths in the UV wavelength range, e.g., at 193 nm, leads to an increase in the refractive index. In the optical plates, this effect is used for wavefront deformation by varying the temperature of the zones. The wavefront deformation can serve to compensate for a momentarily occurring wavefront error caused by the heating of one or more other optical elements through which the useful radiation passes.

[0029] A further aspect of the invention relates to an optical component of the type mentioned at the outset, in which a material of the optical component has an internal engraving, preferably for protecting the adhesive layer from scattered radiation, and / or in which at least one protective layer, preferably for protecting the adhesive layer from scattered radiation, in particular from scattered radiation in the UV wavelength range, is applied to at least one surface of the optical component that is not covered by the adhesive layer. In one embodiment, the internal engraving has at least one preferably planar structure for deflecting, in particular for reflecting and / or scattering, the scattered radiation. The at least one structure of the internal engraving serves to shield the adhesive layer from scattered radiation and is typically arranged between an entrance surface of the optical component, at which the scattered radiation enters the material of the optical component, and the adhesive layer.

[0030] In a further embodiment, the optical component for protecting the adhesive layer from scattered radiation has both the internal engraving and the protective layer, wherein the internal engraving is designed to at least partially redirect the scattered radiation toward the protective layer, in particular to reflect it toward the protective layer and / or to scatter it toward the protective layer. As described above, the internal engraving in this case has a geometry selected such that scattered radiation reaching the internal engraving is at least partially redirected toward the protective layer.

[0031] In a further embodiment, the optical component comprises two preferably plate-shaped optical elements, between which at least one spacer is arranged, wherein the internal engraving is incorporated into the material of the spacer and / or wherein the protective layer is applied to a surface of the spacer not covered by the adhesive layer. As described above, the spacer, or more precisely the adhesive layer applied to a surface of the optical component, serves to attach the optical component to at least one holder of a semiconductor technology system, for example in the form of a projection exposure system.

[0032] In a further development of this embodiment, the protective layer is applied to a surface of the spacer facing away from the adhesive layer, which preferably defines a gap between the optical elements. The semiconductor technology system comprising the optical component can be configured to guide a fluid flow, in particular a gas flow, through the gap to control the temperature of the optical component. The protective layer prevents scattered radiation from the gap from entering the spacer material via the surface facing away from the adhesive layer.

[0033] In a further development, the spacer is connected to a respective optical element via an adhesive bond, which preferably has a plurality of adhesive regions. The internal engraving preferably has at least one preferably planar structure for deflecting, in particular for reflecting and / or scattering, radiation, in particular UV radiation, which enters the spacer at gaps between the adhesive regions during curing of the adhesive regions. In this way, the curing of the adhesive regions can be improved.

[0034] In a further development, at least one of the optical elements has a plurality of temperature-controlled zones. As explained above in connection with the method, the temperature control of the zones can be used to generate wavefront deformations (see also DE102020201723A1). It is understood that both optical elements can have a plurality of separately temperature-controlled, in particular separately heatable, zones.

[0035] A further aspect of the invention relates to a semiconductor technology system, in particular a projection exposure system, which has at least one optical component designed as described above. The semiconductor technology system can be a projection exposure system for exposing a wafer or another system used in the field of semiconductor technology, e.g., an inspection system for inspecting masks, wafers, or the like used in semiconductor technology. In the case of a projection exposure system, the optical component can be arranged, for example, in a projection optics system in order to generate a wavefront deformation.

[0036] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details essential to the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0037] drawing

[0038] Examples of embodiments are shown in the schematic drawing and are explained in the following description.

[0039] Fig. 1 is a schematic representation of a projection exposure system for UV projection lithography with an optical component for wavefront deformation,

[0040] Fig. 2 is a schematic representation of a detail of the optical component of Fig. 1 with an adhesive layer attached to a spacer between two optical plates and struck by scattered radiation,

[0041] Fig. 3 is a schematic representation similar to Fig. 2, in which the spacer has a protective layer and an internal engraving to protect the adhesive layer from scattered radiation, Fig. 4a is a schematic representation similar to Fig. 2, in which the spacer is connected to the optical disks via adhesive areas and when the adhesive areas harden, UV radiation enters the spacer through gaps between the adhesive areas, and

[0042] Fig. 4b is a schematic representation analogous to Fig. 4a, in which the spacer has an internal engraving with flat structures in order to redirect the UV radiation passing through the gaps.

[0043] In the following description of the drawings, identical reference symbols are used for identical or functionally identical components.

[0044] Fig. 1 shows an embodiment of a projection exposure system 1 for UV projection lithography in a schematic representation. In particular, the projection exposure system 1 can be designed for operation at a wavelength of 193 nm. The projection exposure system 1 has an illumination system 2 with an illumination optics 4 and a projection optics 10. The internal structure of the illumination optics 4 and the internal structure of the projection optics 10, which may each comprise, for example, optical elements, sensors, manipulators, etc., are not shown in detail. A lens 6 is indicated in the projection optics 10 as a representative of its optical elements.

[0045] The radiation 5 required for the operation of the projection exposure system 1 is generated by a radiation source 3. The radiation source 3 can, in particular, be an excimer laser, for example an argon fluoride laser, which generates illumination radiation 5 with a wavelength of 193 nm. A reticle holder 8, on which reticle 7, also referred to as a mask, is fixed, is arranged between the illumination optics 4 and the projection optics 10. The reticle holder 8 has a reticle displacement drive 9. A wafer holder 14, which supports a wafer 13 or another substrate and has a wafer displacement drive 15, is arranged downstream of the projection optics 10 as seen in the radiation direction. Furthermore, Fig. 1 shows a control device 25 which is connected to the illumination optics 4, the projection optics 10, the radiation source 3, the reticle holder 8 or the reticle displacement drive 9 and the wafer holder 14 orconnected to the wafer displacement drive 15.

[0046] The projection exposure system 1 serves to image the reticle 7 onto the wafer 13 with high precision. For this purpose, the reticle 7 is illuminated using the illumination optics 4, and the illuminated reticle 7 is imaged onto the wafer 13 using the projection optics 10. The procedure is as follows: The illumination optics 4 uses its optical elements to transform the illumination radiation 5 generated by the radiation source 3 in a precisely defined manner and directs it onto the reticle 7. Depending on the embodiment, the illumination optics 4 can be designed to illuminate the entire reticle 7 or only a portion of the reticle 7. The illumination optics 4 is capable of illuminating the reticle 7 such that virtually identical illumination conditions prevail at every illuminated point on the reticle 7.In particular, the intensity and angular distribution of the incident illumination radiation 5 are almost identical for each illuminated point of the reticle 7.

[0047] The illumination optics 4 are capable of selectively illuminating the reticle 7 with illumination radiation 5 of a multitude of different angular distributions. These angular distributions of the illumination radiation 5 are also referred to as illumination settings. The desired illumination setting is generally selected depending on the structural elements formed on the reticle 7. For example, dipole or quadrupole illumination settings are used relatively frequently, in which the illumination radiation 5 strikes each illuminated point of the reticle 7 from two or four different directions, respectively.Depending on the design of the illumination optics 4, the various illumination settings can be generated, for example, by means of various diffractive optical elements in conjunction with a zoom axicon optic or by means of mirror arrays, each of which has a plurality of small mirrors arranged next to one another and individually adjustable with regard to their angular position.

[0048] The reticle 7 can, for example, be designed as a glass plate which is transparent to the illumination radiation 5 supplied by the illumination optics 4 and on which opaque structures, for example in the form of a chromium coating, are applied.

[0049] The projection exposure system 1 can be configured such that the entire reticle 7 is illuminated simultaneously by the illumination optics 4 and is completely imaged onto the wafer 13 by the projection optics 10 in a single exposure step. Alternatively, the projection exposure system 1 can also be configured such that only a partial area of ​​the reticle 7 is illuminated by the illumination optics 4 at the same time, and the reticle displacement drive 9 is controlled by the control device 25 such that the reticle 7 is moved relative to the illumination optics 4 during the exposure of the wafer 13, and the illuminated partial area thereby travels across the entire reticle 7.The wafer 13 is moved synchronously by a coordinated control of the wafer displacement drive 15, which also takes into account the imaging properties of the projection optics 10, so that the illuminated portion of the reticle 7 is imaged onto a designated portion of the wafer 13. This movement of the reticle 7 and the wafer 13 is also referred to as scanning.

[0050] In order to be able to convert the latent image created by the exposure of the wafer 13 in both embodiments of the projection exposure system 1 into a physical structure, a light-sensitive layer is applied to the wafer 13. The image of the reticle 7 is exposed into this light-sensitive layer, and with the help of subsequent chemical processes, a permanent structure can be created on the wafer 13. As a rule, the reticle 7 is imaged onto the wafer 13 not just once, but multiple times next to one another. For this purpose, the wafer holder 14 is laterally displaced after each image of the reticle 7 onto the wafer 13, in accordance with the size of the image of the reticle 7 on the wafer 13. The image of the reticle 7 can be imaged as a whole or sequentially by scanning. The chemical treatment of the wafer 13 is not started until the desired number of images of the reticle 7 onto the wafer 13 have been performed.

[0051] Also shown in Fig. 1 is an optical component 11, which is attached to a holder 12. The optical component serves to wavefront deform the useful radiation in the form of UV radiation 5, which passes through the projection optics 10.

[0052] Fig. 2 shows an example of the design of the optical component 11 of Fig. 1 in a detailed representation. The optical component 11 has two optical elements 16a, 16b, which are designed in the form of optical plates or flat plates. The two optical plates 16a, 16b are aligned perpendicular to the optical axis of the projection optics 10 indicated in Fig. 1 and parallel to one another. Two spacers 17a, 17b are arranged between the two optical plates 16a, 16b, which hold the two optical plates 16a, 16b at a predetermined distance from one another (see also Fig. 1). In the example shown, the optical plates 16a, 16b are rectangular or cuboid-shaped and each have a thickness of approximately 10 mm in the Z direction of an XYZ coordinate system, which corresponds to the direction of gravity.The two spacers 17a, 17b are mounted in the region of the two lateral ends of the transverse sides of the optical plates 16a, 16b extending in the X-direction and define a gap 18 between the two optical plates 16a, 16b. A gas flow flows through the gap 18, which extends in the longitudinal direction of the two optical plates 16a, 16b, corresponding to the Y-direction of the XYZ coordinate system.

[0053] The two optical plates 16a, 16b each have a plurality of temperature-controlled, or more precisely, heatable, zones Z1, Z2, Z3, ... or ZT, Z2', Z3', ..., as indicated in Fig. 1. For the separate heating of the zones Z1, Z2, Z3, ... or ZT, Z2', Z3', ..., each of the two optical plates 16, 16b has a thermal manipulator with a plurality of electrically conductive ohmic structures. For details of the design of the thermal manipulators, reference is made to DE102020201723A1. The temperature in the individual zones Z1, Z2, Z3, ... or ZT, Z2', Z3', ... can be adjusted by the action of the control device 25 on the thermal manipulators. The local temperature of the optical plates 16a, 16b influences the local refractive index of the optical plates 16a, 16b, which is why the optical component 11 is used for wavefront deformation of the UV radiation 5, which forms the useful radiation of the projection exposure system 1.

[0054] The spacers 17a, 17b of the optical component 11 have a rectangular cross-section. The right-hand spacer 17b shown in Fig. 2 has a first flat surface 19a facing the intermediate space 18 and a second flat surface 19b facing away from the intermediate space 18. An adhesive layer 20 is applied to the surface 19b of the spacer 17b facing away from the intermediate space 18. The adhesive layer 20 connects the optical component 11 to the holder 12, more precisely to a holding element 21 of the holder 12. The optical component 11 is held in the projection optics 10 by means of several holding elements 21 of the holder 12. In the example shown, the holding elements serve to mount the optical component 11 with low vibration and can be designed, for example, as bipods.The adhesive layer 20 does not extend over the entire surface 19b of the spacer 17b facing away from the intermediate space 18, but is limited to a respective surface area at which the spacer 17b is connected to the associated holding element 21.

[0055] The spacers 17a, 17b are arranged outside the beam path of the UV radiation 5, which forms the useful radiation of the projection exposure system 1. The UV radiation 5 passes largely along the beam path through the two optical plates 16a, 16b and the intermediate space 18. A portion of the UV radiation 5 is scattered by the two optical plates 16a, 16b or by other components of the projection optics 10 and forms scattered radiation 22, which propagates in different directions and passes through the spacer 17b shown in Fig. 2 as well as the two optical plates 16a, 16b and strikes the adhesive layer 20. The scattered radiation 22 typically leads to degradation of the adhesive, which in the worst case can cause the optical component 11 to detach from the respective holding element 21 or from the holder 12.

[0056] To prevent this, in the example shown in Fig. 3, the adhesive layer 20 is protected from the scattered radiation 22 by an internal engraving 23 being introduced into the material of the spacer 17b, which, like the material of the two optical plates 16a, 16b, is quartz glass. In addition, a UV protection layer 24 is applied to the surface 19a of the spacer 17b that laterally delimits the intermediate space 18. In the example shown, the UV protection layer 24 extends over the entire surface 19a delimiting the intermediate space 18 and protects the adhesive layer 20 from scattered radiation 22, which would penetrate the material of the spacer 17b without the UV protection layer 24. The heat absorbed by the UV protection layer 24 upon absorption of the scattered radiation 22 is transported away with the aid of the gas flow described above.

[0057] As can also be seen in Fig. 2, the two optical plates 16a, 16b are each connected to the right-hand spacer 17b via an adhesive connection having a plurality of adhesive regions 26a-c and 27a-c, respectively. Between each two adjacent adhesive regions 26a-c, 27a-c, there are gaps 28a, b and 29a, b, respectively, through which scattered radiation 22 propagating within the optical plates 16a, 16b can enter the spacer 17b. The adhesive layer 20 is protected from this scattered radiation 22 by means of the internal engraving 23, which for this purpose has two flat structures 30a, b, which are designed in the manner of spherical segments and which were introduced into the material of the spacer 17b in the form of an internal laser engraving.The two planar structures 30a, b have a comparatively small thickness of a few micrometers and extend essentially over the entire portion of the surface 19b to which the adhesive layer 20 is applied. As indicated in Fig. 3, the scattered radiation 22 impinging on the planar structures 30a, b is deflected, or more precisely, reflected. A portion of the reflected scattered radiation 22 strikes the UV protection layer 24 and is absorbed by it.

[0058] Unlike what is shown in Fig. 3, it is also possible for only the protective layer 24 or only the internal engraving 23 to be used to protect the adhesive layer 20. The planar structures 30a, b of the internal engraving 23, which serve to protect the adhesive layer 20, can also deviate from the shape shown in Fig. 3. A suitable geometry of the planar structures 30a, b can be determined, for example, by a scattered light simulation. Instead of planar structures 30a, b, the internal engraving 23 can also have one or more three-dimensional structures that deflect the scattered radiation 22 in order to protect the adhesive layer 20 from degradation.

[0059] It is understood that the internal engraving 23 may also have more or fewer than the two planar structures 30a, b shown in Fig. 3. Fig. 4a, b shows an example of such an internal engraving 23, which, in addition to the two planar structures 30a, b shown in Fig. 3, has two further planar structures 30c, d. The further planar structures 30c, d also protect the adhesive layer 20 (not illustrated in Fig. 4a, b) from scattered radiation 22, but they also serve a further purpose, namely to optimize the curing of the adhesive regions 26a-c, 27a-c between the spacer 17b and the first optical disk 16a or the second optical disk 16b. As shown in Fig. 4a, b, for the curing of the adhesive areas 26a-c, UV radiation 31 is irradiated perpendicularly onto the side of the first optical plate 16a facing away from the intermediate space 18.The irradiation is homogeneous, so that a part of the UV radiation 31 radiated for curing passes through the gaps 28a, b between the adhesive areas 26a-c formed between the first optical plate 17a and the spacer 17b, and reaches the adhesive areas 27a-c between the spacer 17b and the second optical plate 16b, which are partially cured, which is generally undesirable.

[0060] In the example shown in Fig. 4b, the two further planar structures 30c, d serve to prevent the UV radiation 31 passing through the gaps 28a, b from reaching the adhesive regions 27a-c on the second optical plate 16b. As can also be seen in Fig. 4b, the first of the further planar structures 30c has a curvature which is selected such that the UV radiation 31 passing through the gaps 28a, b is reflected back to the adhesive regions 26a-c, whereby a homogeneous curing of the adhesive at the adhesive regions 26a-c can be achieved. The same applies correspondingly to the second of the further planar structures 30d with regard to the adhesive regions 27a-c between the spacer 17b and the second optical plate 16b. It is understood that the UV radiation 31 shown in Fig. 4a, b is only used for curing the adhesive areas 26a-c, 27a-c.The projection exposure system 1, more precisely the projection optics 10, has shields (not shown in the illustration) which prevent scattered radiation 22 in the region of the spacers 17a, 17b from impinging on the respective outer sides of the optical plates 16a, 16b and from passing through the gaps 28a, b and 29a, b, respectively.

Claims

Patent claims 1 . Method for protecting an adhesive layer (20) on an optical component (11), in particular on an optical component (11) for wavefront deformation, from scattered radiation (22), in particular from scattered radiation (22) in the UV wavelength range, comprising: protecting the adhesive layer (20) from the scattered radiation (22) by introducing an internal engraving (23) into a material of the optical component (11) and / or Protecting the adhesive layer (20) from the scattered radiation (22) by applying at least one protective layer (24) to at least one surface (19a) of the optical component (11) not covered by the adhesive layer (20).

2. Method according to claim 1, wherein, when the internal engraving (23) is introduced into the material of the optical component (11), at least one preferably planar structure (30a-d) is produced for deflecting, in particular for reflecting and / or scattering, the scattered radiation (22).

3. Method according to claim 1 or 2, wherein the adhesive layer (20) is protected from the scattered radiation (22) by the internal engraving (23) and by the protective layer (24), wherein the internal engraving (23) at least partially deflects the scattered radiation (22) to the protective layer (24), in particular reflects and / or scatters it to the protective layer (24).

4. Method according to one of the preceding claims, in which the optical component (11) has two preferably plate-shaped optical elements (16a, 16b), between which at least one spacer (17a, 17b) is arranged, wherein the internal engraving (23) is introduced into the material of the spacer (17b) and / or wherein the protective layer (24) is applied to a surface (19a) of the spacer (17b) not covered by the adhesive layer (24).

5. The method according to claim 4, wherein the protective layer (24) is applied to a surface (19a) of the spacer (17b) facing away from the adhesive layer (20), which surface preferably delimits an intermediate space (18) between the two optical elements (16a, 16b).

6. The method according to claim 4 or 5, wherein the spacer (17b) is connected to a respective optical element (16a, 16b) via an adhesive connection, which preferably has a plurality of adhesive areas (26a-c, 27a-c), wherein during the introduction of the internal engraving (23) preferably at least one preferably planar structure (30c, d) for deflecting, in particular for reflecting and / or scattering, radiation, in particular UV radiation (31), is produced, which enters the spacer (17b) at gaps (28a, b; 29a, b) between the adhesive areas (26a-c, 27a-c) when the adhesive areas (26a-c, 27a-c) harden.

7. Method according to one of claims 4 to 6, wherein at least one of the optical elements (16a, 16b) has a plurality of temperature-controlled zones (Z1, Z2, Z3; Z1', Z2', Z3') in order to generate a wavefront deformation.

8. Optical component (11), in particular for wavefront deformation, comprising: an adhesive layer (20), characterized in that a material of the optical component (11) has an internal engraving (23), preferably for protecting the adhesive layer (20) from scattered radiation (22), and / or that at least one protective layer (24), preferably for protecting the adhesive layer (20) from scattered radiation (22), in particular from scattered radiation (22) in the UV wavelength range, is applied to at least one surface (19a) of the optical component (11) which is not covered by the adhesive layer (20).

9. Optical component according to claim 8, wherein the internal engraving (23) has at least one preferably planar structure (30a-d) for deflecting, in particular for reflecting and / or scattering, the scattered radiation (22).

10. Optical component according to claim 8 or 9, which has both the internal engraving (23) and the protective layer (24) for protecting the adhesive layer (24) from scattered radiation (22), wherein the internal engraving (23) is designed to at least partially redirect the scattered radiation (22) to the protective layer (24), in particular to reflect it to the protective layer (24) and / or to scatter it to the protective layer (24).

11. Optical component according to one of claims 8 to 10, which has two preferably plate-shaped optical elements (16a, 16b), between which at least one spacer (17a, 17b) is arranged, wherein the internal engraving (23) is introduced into the material of the spacer (17b) and / or wherein the protective layer (24) is applied to a surface (19a) of the spacer (17b) not covered by the adhesive layer (20).

12. Optical component according to claim 11, wherein the protective layer (24) is applied to a surface (19a) of the spacer (17b) facing away from the adhesive layer (20), which surface preferably delimits an intermediate space (18) between the two optical elements (16a, 16b).

13. Optical component according to one of claims 11 or 12, in which the spacer (17a, 17b) is connected to a respective optical element (16a, 16b) via an adhesive connection, which preferably has a plurality of adhesive regions (26a-c, 27a-c), wherein the internal engraving (23) preferably has at least one, in particular planar, structure (30c, d) for deflecting, in particular for reflecting and / or scattering, radiation, in particular UV radiation (31), which enters the spacer (17b) at gaps (28a, b; 29a, b) between the adhesive regions (26a-c, 27a-c) when the adhesive regions (26a-c, 27a-c) cure.

14. Optical component according to one of claims 11 to 13, wherein at least one of the optical elements (16a, 16b) has a plurality of temperature-controllable zones (Z1, Z2, Z3; Z1', Z2', Z3').

15. A semiconductor technology system, in particular a projection exposure system (1), comprising: at least one optical component (11) according to one of claims 8 to 14.

Images