Optical assembly

Abstract

An optical assembly (28) has at least one optical component (13) for guiding useful light (4). A holder (29) for the optical component (13) is connected to the optical component (13) via an adhesive bond (31). At least one protective layer (33a, 33b) is arranged such that it covers the adhesive bond (31) on at least one protective side and prevents the useful light (4) from striking the adhesive bond (31) from the protective side. This results in an optical assembly with high stability.

Description

[0001] The invention relates to an optical assembly comprising an optical component for guiding useful light and a holder for the optical component. Furthermore, the invention relates to a retrofit kit for retrofitting such an optical assembly, a lighting optic comprising such an optical assembly, a projection optic comprising such an optical assembly, an optical system comprising such a lighting optic and / or such a projection optic, a projection exposure system comprising such an optical system, a method for manufacturing a micro- or nanostructured component with such a projection exposure system, and a structured component manufactured by such a method.

[0002] An optical assembly of the type mentioned above is known as a mounted optical component from WO 2005 / 015 310 A2, DE 10 2004 059 493 A1, WO 2009 / 095 052 A1, DE 196 53 983 A1, US 5,982,558, US 7,551,361 B2 and WO 2016 / 188 739 A1. An optical mount is known from EP 0 895 113 B1. Further optical assemblies or components thereof are known from DE 10 2021 214 140 A1 and DE 10 2011 080 639 A1.

[0003] It is an object of the present invention to further develop an optical assembly of the type mentioned above in such a way as to result in high stability.

[0004] This problem is solved according to the invention by an optical assembly having the features specified in claim 1.

[0005] The protective layer prevents the adhesive bond from being exposed to unwanted ambient light and / or stray light. Stray light can be ambient light outside the intended beam path or light or radiation of a different wavelength than the ambient light. This prevents unwanted degradation of the adhesive bond due to exposure to ambient light or stray light, and thus prevents any undesirable reduction in the service life of the optical assembly. The protective layer can be absorbent, reflective, and / or scattering. The ambient light can have a wavelength in the EUV range. The ambient light can have a wavelength of 193 nm. The ambient light can have a wavelength of 248 nm.

[0006] An embodiment according to claim 2 provides particularly effective protection of the adhesive bond.

[0007] The thicknesses of the protective layer according to claim 3 have proven effective in practice and enable a compact design of the optical assembly. Retrofitting an existing optical assembly with such a protective layer is also possible without changes to the optical design. The thickness of the protective layer can range from 25 µm to 200 µm, from 30 µm to 100 µm, and can particularly be in the range of 50 µm.

[0008] One embodiment of the protective layer according to claim 4 has proven particularly effective. It is especially advantageous if the protective film can be precisely manufactured during the production of the optical assembly and is, for example, made of a film material that can be subsequently trimmed.

[0009] An embodiment according to claim 5 can avoid an additional supporting component for the protective layer.

[0010] An adhesive version of the protective layer according to claim 6 can be realized with comparatively low manufacturing effort. The protective layer can be self-adhesive. The adhesive layer can, for example, be as thick as the protective film, but alternatively it can also be thinner or, if necessary, thicker than the protective film. Alternatively or in addition to an adhesive bond, the protective layer can also be mechanically connected to the optical component and / or the mounting.

[0011] Materials for the protective layer according to claim 7 represent a good combination of shielding against useful light and mechanical and / or thermal stability. If a metal is used for the protective layer, it can be coated with an absorbing material. Alternatively or additionally, the surface of the protective layer can be structured to optimize its shielding properties.

[0012] In an embodiment of the protective layer according to claim 8, the protective layer can additionally have the function of an aperture for the useful light.

[0013] The advantages of a retrofit kit according to claim 9 initially correspond to those already explained above with reference to the optical assembly and the protective layer. The retrofit kit can comprise multiple protective films. These multiple protective films can have different aperture sizes and / or different outer contour designs. The retrofit kit can also include processing tools for preparing the respective protective film, adhesive material, and application and positioning aids for correctly applying and positioning the respective protective film onto the optical component.

[0014] The advantages of an illumination optic according to claim 10 and a projection optic according to claim 11 correspond to those already explained above with reference to the optical assembly. These optics can be components of a lithography projection exposure system.

[0015] The advantages of an optical system according to claim 12, a projection exposure system according to claim 13, a manufacturing method according to claim 14, and a structured component according to claim 15 correspond to those already explained above with reference to the optical assembly, the retrofit kit, the illumination optics, and the projection optics. The light source of the illumination system can be a mercury vapor lamp, an excimer laser, or an LED light source.

[0016] A structured component, in particular a microchip, for example a memory chip, can be manufactured.

[0017] Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. This drawing shows: Fig. 1 in a meridional section optical main groups of a projection exposure system for microlithography, comprising an illumination optic for illuminating an object field with illumination and imaging light and a projection optic for imaging the object field into an image field, comprising a plurality of optical components for guiding the illumination and imaging light; Fig. 2 a fractured axial section through an optical assembly of the projection exposure system, comprising one of the optical components, a holder for this optical component and protective layers arranged on both sides of the optical assembly; and Fig. 3 in one to Fig. 2 similar, in this case unbroken, sectional views show another embodiment of such an optical assembly, comprising two spaced-apart optical components, a holder for these optical components and a protective layer arranged in this case on one side of the optical assembly.

[0018] A projection exposure system 1 is, with regard to its main optical groups, in which Fig. 1 shown in the meridional section.

[0019] To facilitate the representation of spatial relationships, an xyz coordinate system is used below. In the Fig. 1. The x-axis runs perpendicular to the plane of the drawing and into it. The y-axis runs in the Fig. 1 to the left. The z-axis runs in the Fig. 1 up.

[0020] The dashed line is in the Fig. Figure 1 indicates an optical axis 2 that runs through the entire optical system of the projection exposure system 1, starting from a light source 3. This optical axis 2 is present in the Fig. In the illustrated version of the projection exposure system 1, the folds are multiple times, each time by 90°. Such folds can also be designed differently or may even be omitted entirely.

[0021] The light or radiation source 3 of the projection exposure system 1 generates useful light in the form of an illumination or imaging beam 4, which is in the Fig. 1 is illustrated by marginal rays. The useful light 4 is also referred to as illumination light or imaging light. The useful light 4 has a wavelength in the deep ultraviolet (DUV) range, for example, in the range between 100 nm and 200 nm, or in the ultraviolet (UV) range between 200 nm and 400 nm. Alternatively, the useful light 4 can also have a wavelength in the extreme ultraviolet (EUV) range, particularly between 5 nm and 30 nm. Example wavelengths of the radiation source 3 are 365 nm, 248 nm, and 193 nm. Depending on the radiation source 3 used, the useful wavelength spectrum is narrowband, but can also be broadband, for example, when using a mercury discharge lamp.

[0022] A lighting optic 5 of the projection exposure system 1 guides the useful light 4 along an illumination beam path from the radiation source 3 to an object plane 6 of the projection exposure system 1. Together with the light source 3, the lighting optic 5 forms an illumination system of the projection exposure system. In the object plane 6, an object to be imaged by the projection exposure system 1 is arranged in the form of a reticle 7. The reticle 7 is in the Fig. 1 is shown with a dashed line. Reticule 7 is supported by a holding device (not shown) that allows for controlled scan displacement or stepwise displacement. It can be, as in the Fig. Figure 1 illustrates that a transmissive reticle can be used, but also, depending on the design of the projection exposure system 1, a reflective reticle. The reticle 7 is arranged in an object field 6a in the object plane 6.

[0023] A collector 8 in the form of an ellipsoidal mirror directs the illumination light 4 emanating from a source area of ​​the light source 3 into an intermediate focus 9. A shutter is located there to control the release of the illumination light 4 to the components of the optical system that follow the optical axis 2. A safety shutter 10 is also arranged in the beam path of the illumination light 4 upstream of this intermediate focus shutter.

[0024] Downstream of the intermediate focus 9 in the beam path of the illumination light 4 is a pupil-shaping optic 11 of the illumination optic 5. The pupil-shaping optic 11 serves to generate a defined intensity distribution of the illumination light 4 in a downstream pupil plane of the illumination system. The pupil-shaping optic 11 also serves as an adjustment device for specifying different illumination settings with different maximum object field illumination angles. With the pupil-shaping optic 11, an image of the light source in the intermediate focus 9 is projected into a pupil plane 12 of the illumination optic 5. The pupil-shaping optic 11 includes an interference filter 13 and, downstream of this, an axicon module 14 with two axicon elements 15, 16.The Axikon module 14 allows a maximum object field illumination angle to be set within a range of illumination angles for illuminating object field 6a.

[0025] A pupil radius σ serves as a measure for the maximum object field illumination angle set via the pupil-shaping optics 11. 90 , which specifies the radius within which 90% of the illumination energy incident on the pupil plane 12 or a downstream pupil plane of the illumination optics 5 is located, for a specific pupil illumination of the pupil plane 12 or a subsequent pupil plane of the illumination optics 5. σ 90 is given in relative pupil coordinates. The value “σ 90 "= 1" indicates that the edge of the maximum illuminable pupil of the lighting system has been reached.

[0026] Downstream of the pupil plane 12 is an illumination light mixing unit 17. The illumination light mixing unit 17 comprises a primary optical rod 17a in the illumination light beam path downstream of the pupil plane 12 and a secondary optical rod 17b downstream in the illumination light beam path. The optical rods 17a and 17b can have hexagonal and / or rectangular cross-sections. The illumination light mixing unit 17 can also consist of several consecutive rod sections, possibly with different cross-sections. An entry plane of the optical rod of the illumination light mixing unit 17 can coincide with the pupil plane 12. The optical rods 17a and 17b are made of glass, for example, boron crown glass or quartz glass. The rods 17a and 17b can also be made of calcium fluoride (CaF₂).

[0027] In the area of ​​the lighting light mixing unit 17, an lighting light beam path is deflected by 90° by means of a deflecting prism 18, so that the optical axis 2 no longer runs along the positive z-direction, but along the positive y-direction of the xyz coordinate system. Fig. 1. The deflecting prism 18 is made of glass, for example borosilicate glass or quartz glass or CaF2.

[0028] The two optical rods 17a, 17b and the intermediate deflecting prism 18 form the lighting-light mixing unit 17, which is an optical assembly of the lighting optics 5. Various designs of this optical assembly are described below. Fig. 2 and Fig. 3 explained in more detail.

[0029] At the exit point of the illumination light 4 from the illumination light mixing unit 17, there is an intermediate field plane 19 of the illumination optics 5. In this intermediate field plane 19 is an aperture 20 for defining an edge boundary of the object field 6a. The aperture 20 is also referred to as a REMA aperture (Reticle Masking System for stopping down the reticle 7).

[0030] The intermediate field plane 19 is imaged onto the object plane 6 by an imaging optic 21, also known as a REMA lens. The imaging optic 21 includes a 90° folding mirror 21a, so that the optical axis 2, which until then ran along the positive y-direction, now runs in the negative z-direction. A further pupil plane 22 lies between the field planes 19 and 6.

[0031] The object field 6a is projected onto an image field 24 in an image plane 25 by means of a projection optic 23. A wafer 26 is arranged in the image plane 25 in the area of ​​the image field 24. This wafer is supported by a holding device (not shown) which enables controlled scan displacement of the wafer 26 or stepwise displacement of the wafer 26.

[0032] Between the object plane 6 and the image plane 25 lies a pupil plane 27 of the projection optics 23. In this pupil plane 27, an aperture diaphragm can be arranged to define a pupil of the projection optics 23 at the edge.

[0033] Within the illumination optics 5, comprising the pupil-forming optics 11 and the imaging optics 21, and also within the projection optics 23 of the projection exposure system 1, there are multiple optical assemblies whose optical components serve to guide the useful light 4. These optical components are each held by a bracket on a frame of the projection exposure system 1. One such optical assembly 28 is described below with reference to the Fig. Section 2 explains this in more detail using the example of the interference filter 13 as an optical component of this optical assembly 28. The other optical components for guiding the useful light 4 between the light source 3 and the wafer 26 can also be parts of corresponding optical assemblies.

[0034] The optical assembly 28 has, in addition to the interference filter 13, a holder 29 which is designed as a filter mount and which attaches the interference filter 13 to a surface in the Fig. The support frame 30 is fixed to two sections. The holder 29 is adhesively connected to the optical component 13 via a circumferential adhesive bond 31.

[0035] The optical component 13 has an aperture 32 for the passage of the useful light 4, which is in the Fig. 2 is illustrated as a plurality of parallel individual rays. This aperture 32 corresponds to the refracted representation of the optical component 13 in the Fig. 2 is also shown broken off to the left.

[0036] Outside this aperture opening 32, protective layers 33a and 33b are arranged on both sides of the optical component 13, i.e., on an entrance surface 13a and on an exit surface 13b. This arrangement of the protective layers 33a and 33b on the optical component 13 is such that the adhesive bond 31 is covered on both sides, i.e., in the axial direction towards the entrance surface 13a (opposite the direction of the useful light 4 in the useful light beam path) and also towards the exit surface 13b (in the direction of the useful light 4 in the useful light beam path), i.e., towards two protective sides.

[0037] The protective layers 33a and 33b each cover an edge area of ​​the optical component 13, an edge area of ​​the holder 29 facing the optical component 13, and the entire intervening adhesive connection 31.

[0038] This arrangement of the protective layers 33a and 33b prevents the useful light 4 and, in particular, scattered light 4 from being scattered away from the desired illumination and imaging beam path of the useful light 4. S from the respective protective side onto the adhesive bond 31. This is in the Fig. 2. For example, using scattered light individual rays. 4 S This illustrates that the light rays from both sides of the optical assembly 28 run towards the adhesive joint 31 and do not penetrate the adhesive joint 31 due to the protective layer 33a or 33b. The scattered light 4 S The wavelength of the useful light can be 4. Alternatively, the scattered light can be 4. S also have a wavelength 4 different from the useful light.

[0039] The protective layers 33a and 33b are for the useful light 4 and especially for the scattered light 4 SAbsorbing. Alternatively or additionally, a reflective or, if necessary, scattering and / or diffracting design of the respective protective layer 33a, 33b is also possible. This ensures that undesirable degradation of the adhesive material of the adhesive bond 31 under the influence of scattered light 4 is prevented. S prevented.

[0040] The respective protective layer 33a, 33b has a layer thickness in the range between 10 µm and 1000 µm. This thickness can be in particular in the range between 25 µm and 100 µm and, for example, in the range of 50 µm.

[0041] The respective protective layer 33a, 33b is designed as a protective film.

[0042] The respective protective layer 33a, 33b is connected to both the optical component 13 and the holder 29, namely bonded to it.

[0043] The protective layer 33a, 33b is adhesively bonded. The respective protective layer 33a, 33b is thus connected to the optical component 13 and to the holder 29 via an adhesive layer. The protective layer 33a, 33b is self-adhesive.

[0044] The adhesive layer can be as thick as the protective film. Alternatively, the adhesive layer can be thinner or thicker than the protective film.

[0045] The respective protective layer 33a, 33b is made of polyamide. Alternatively, the protective layer can also be made of polyimide or metal. The respective protective layer 33a, 33b can have an absorbing and / or diffusing and / or scattering coating.

[0046] As an alternative to bonding the protective layer 33a, 33b to the optical component 13 or the holder 29, the respective protective layer 33a, 33b can also be mechanically connected to the optical component 13 and / or to the holder 29, for example by clamping it to the holder 29.

[0047] The protective layer 33a / 33b limits the aperture opening 32, i.e., the usable aperture of the optical component 13, all around, which in the Fig. 2 is not shown. The protective layer 33 (a / b), which can also be manufactured in one piece, can simultaneously function as an aperture diaphragm for the optical component 13, i.e., for the interference filter.

[0048] The protective layer 33a, 33b can be designed as part of a retrofit kit for applying the protective layer 33a, 33b to the respective optical component, for example, the interference filter 13, to complete an assembly that initially lacks such a protective layer into an optical assembly with such a protective layer. Such a retrofit kit can have several protective layers, which can be designed, in particular, as optionally self-adhesive protective films. These multiple protective layers of the retrofit kit can, for example, be designed as circumferential protective layer apertures with several aperture sizes and / or with several aperture outer contour designs and / or several protective layer thicknesses and / or several protective layer connection variants.These different connection options can involve different adhesive techniques (self-adhesive, additional adhesive, for example 2-component adhesive) and / or variations of a mechanical connection.

[0049] Based on the Fig. 3 below describes a further embodiment of an optical assembly 34, which, like the optical assembly 28, according to Fig. 2 can be used as part of an optical system of the projection exposure unit 1 for guiding the useful light 4. The optical assembly 34 can, in particular, be designed as a correction component for correcting guiding or imaging errors of the illumination optics 5 and / or the projection optics 23. Components and functions corresponding to those described above with reference to the Fig. 1 and Fig. 2 and in particular with reference to the Fig. Items 2, which have already been explained, bear the same designations or reference numbers and will not be discussed again in detail.

[0050] The optical assembly 34 has three optical components 35, 36, 37, which are located in the Fig. 3 are illustrated as plane-parallel plates, but can also have a non-planar surface design of an entry or exit surface.

[0051] A distance between the optical components 35, 36, 37 of the optical assembly 34 can be specified by spacers (not shown). This distance is located along an illumination or imaging beam path of the useful light 4.

[0052] The optical components 35 and 36 are connected to the multi-part support frame 30 via adhesive layers 38 through a mounting 39, which in turn is designed as a socket and can be multi-part. The adhesive layers 38 serve to bond the mounting 39 to the optical components 35 to 37 on the one hand and to the support frame 30 on the other.

[0053] The optical assembly 34 includes a protective layer 33, which is arranged on an exit side of the optical component 36 downstream in the beam path of the useful light 4 and is connected to the exit surface 13b of the optical component 36. This connection is in accordance with what was described above in connection with the protective layers 33a, 33b. Fig. 2 was explained.

[0054] Beyond the aperture opening 32, the protective layer 33 of the optical assembly 34 covers an edge region of the optical component 36, a space between the optical component 36 and the support frame 30, and also an edge region of the support frame 30 facing the optical component 36.

[0055] This arrangement of the protective layer 33 prevents, as in the Fig. 3 in turn illustrates by scattered light individual rays 4s that scattered light incident on the optical assembly 34 from the exit side of the optical component 36 4 S This exit side is therefore also the protective side of the optical assembly 34.

[0056] The scattered light 4 Sis effectively shielded from the protective layer 33 towards the protective side and cannot come into contact with any of the adhesive layers 38 described above between bonded elements of the optical assembly 34.

[0057] Degradation of the adhesive material of the adhesive layers 38 is effectively prevented by the protective layer 33 of the optical assembly 34.

[0058] On the inlet side, a gap between the inlet surface 13a of the optical component 35, which guides the beam path, and the support frame 30 is covered by a circumferential sealing element 40. This sealing element 40 is in turn bonded to the inlet surface 13a of the optical component 35 on one side and to the support frame 30 on the other side via adhesive layers 38.

[0059] The adhesive material of the adhesive layers 31, 38 described above may be an acrylate adhesive material.

[0060] Insofar as the protective layer 33 (a / b) is absorbent for the scattered light 4 S Depending on the design, the protective layer can be made of a material that is temperature-resistant up to 200 °C, 250 °C, 300 °C, 350 °C, or even 400 °C. The respective protective layer 33 (a / b) can be made of a material with a low outgassing rate, for example, with outgassing values ​​below 0.1 ng / (cm²). 2 h) be manufactured for substances that are not highly volatile (condensables).

[0061] Using the projection exposure system 1, which either has optical assemblies 28, 34 as described above or in which such optical assemblies have been retrofitted using a retrofit kit mentioned above, at least a part of the reticulum 7 is imaged onto an area of ​​a photosensitive layer on the wafer 26 for the lithographic fabrication of a micro- or nanostructured device. Depending on whether the projection exposure system 1 is configured as a scanner or a stepper, the reticulum 7 and the wafer 26 are moved continuously in the y-direction in scanner mode or stepwise in stepper mode, synchronized over time. 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] WO 2005 / 015 310 A2

[0002] DE 10 2004 059 493 A1

[0002] WO 2009 / 095 052 A1

[0002] DE 196 53 983 A1

[0002] US 5,982,558

[0002] US 7,551,361 B2

[0002] WO 2016 / 188 739 A1

[0002] EP 0 895 113 B1

[0002] DE 10 2021 214 140 A1

[0002] DE 10 2011 080 639 A1

[0002]

Claims

[1] Optical assembly (28; 34) - with at least one optical component (13; 35, 36, 37) for guiding useful light (4), - with a holder (29) for the optical component (13; 35, 36, 37) which is connected to the optical component (13; 35, 36, 37) via an adhesive connection (31; 38), - with at least one protective layer (33a, 33b; 33) arranged to cover the adhesive joint (31; 38) on at least one protective side and to prevent the useful light (4) from striking the adhesive joint (31; 38) from the protective side. [2] Optical assembly according to claim 1, characterized by at least two protective layers (33a, 33b) that cover the adhesive joint (31) on both sides with respect to an arrangement plane of the optical component (13) and prevent the useful light (4) from striking the adhesive joint (31) from these two sides. [3] Optical assembly according to claim 1 or 2, characterized by , that the protective layer (33a, 33b; 33) has a thickness in the range between 10 µm and 1000 µm. [4] Optical assembly according to any one of claims 1 to 3, characterized by , that the protective layer (33a, 33b; 33) is designed as a protective film. [5] Optical assembly according to any one of claims 1 to 4, characterized by , that the protective layer (33a, 33b; 33) is connected to the optical component (13; 35, 36, 37) and / or to the holder (29). [6] Optical assembly according to claim 5, characterized by , that the protective layer (33a, 33b; 33) is connected to the optical component (13; 35, 36, 37) and / or to the holder (29) via an adhesive layer. [7] Optical assembly according to any one of claims 1 to 6, characterized by , that the protective layer (33a, 33b; 33) is made of at least one of the following materials: - Polyamide - Polyimid - Metal. [8] Optical assembly according to any one of claims 1 to 7, characterized by , that the protective layer (33a, 33b; 33) circumferentially limits a usable aperture (32) of the optical component (13; 35, 36, 37). [9] Retrofit kit with at least one protective film (33a, 33b; 33) according to one of claims 1 to 8 for application to an optical component (13; 35, 36, 37) for completing an optical assembly (28; 34) according to one of claims 1 to 8. [10] Lighting optics (5) with an optical assembly (28; 34) according to one of claims 1 to 8. [11] Projection optics (23) with an optical assembly (28; 34) according to any one of claims 1 to 8. [12] Optical system comprising an illumination optic according to claim 10 for illuminating an object field (6a) in which an object (7) to be illuminated and imaged can be arranged, and / or comprising a projection optic (23) according to claim 11 for imaging the object field (6a) into an image field (24) in which a section of a substrate (26) can be arranged. [13] Projection exposure system with an optical system according to claim 12. [14] Methods for manufacturing structured components comprising the following steps: - Providing a wafer (26) on which at least part of a layer of a photosensitive material is applied, - Providing a reticulum (7) that contains structures to be mapped, - Providing a projection exposure system (1) according to claim 13, - Projecting at least part of the reticulum (7) onto an area of ​​the wafer layer (26) using the projection exposure system (1). [15] Structured component manufactured according to a method according to claim 14.

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