EP4200879A1 - Élément optique réfléchissant, unité d'éclairage optique, système d'éclairage par projection et procédé de fabrication de couche de protection - Google Patents

Élément optique réfléchissant, unité d'éclairage optique, système d'éclairage par projection et procédé de fabrication de couche de protection

Info

Publication number
EP4200879A1
EP4200879A1 EP21743436.4A EP21743436A EP4200879A1 EP 4200879 A1 EP4200879 A1 EP 4200879A1 EP 21743436 A EP21743436 A EP 21743436A EP 4200879 A1 EP4200879 A1 EP 4200879A1
Authority
EP
European Patent Office
Prior art keywords
optical element
protective layer
structured surface
reflective
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21743436.4A
Other languages
German (de)
English (en)
Inventor
Sandro HOFFMANN
Valentin Jonatan Bolsinger
Sandra HASCHKE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Carl Zeiss SMT GmbH
Original Assignee
Carl Zeiss SMT GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carl Zeiss SMT GmbH filed Critical Carl Zeiss SMT GmbH
Publication of EP4200879A1 publication Critical patent/EP4200879A1/fr
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/06—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators
    • G21K1/062—Devices having a multilayer structure
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
    • G03F7/2008—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image characterised by the reflectors, diffusers, light or heat filtering means or anti-reflective means used
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70058—Mask illumination systems
    • G03F7/7015—Details of optical elements
    • G03F7/70158—Diffractive optical elements
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70058—Mask illumination systems
    • G03F7/70191—Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70058—Mask illumination systems
    • G03F7/702—Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
    • G03F7/70575—Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
    • G03F7/7095—Materials, e.g. materials for housing, stage or other support having particular properties, e.g. weight, strength, conductivity, thermal expansion coefficient
    • G03F7/70958—Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
    • G03F7/70983—Optical system protection, e.g. pellicles or removable covers for protection of mask
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
    • G02B5/0825—Multilayer mirrors, i.e. having two or more reflecting layers the reflecting layers comprising dielectric materials only
    • G02B5/0833—Multilayer mirrors, i.e. having two or more reflecting layers the reflecting layers comprising dielectric materials only comprising inorganic materials only
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K2201/00—Arrangements for handling radiation or particles
    • G21K2201/06—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
    • G21K2201/067—Construction details

Definitions

  • Reflective optical element illumination optics
  • the invention relates to a reflective optical element, in particular for an illumination optics of a projection exposure system, comprising: a structured surface, which preferably forms a grid structure, and a reflective coating, which is applied to the structured surface.
  • the invention also relates to illumination optics for a projection exposure system, which has at least one such reflecting optical element, a projection exposure system with such illumination optics, and a method for forming a protective layer on an optical element.
  • both the illumination optics and the projection optics are typically exclusively reflective optical elements, in particular in the form of mirrors.
  • the mirrors used there have a substrate on which a reflective coating is applied to reflect the EUV radiation.
  • the reflective coating can be designed as a multi-layer coating, which acts as an interference layer system for the operating wavelength. If the operating wavelength is around 13.5 nm, the reflective multi-layer coating can have alternating layers of molybdenum and silicon, for example.
  • the reflective coating can be applied directly to the material of the substrate, but it is also possible for one or more functional layers to be arranged between the reflective coating and the material of the substrate, which serve, for example, to protect the substrate, as a polishing layer or as an adhesion promoter .
  • the residual gas present in the vicinity of the reflecting optical elements absorbs EUV radiation and thereby reduces transmission when passing through the projection exposure system. For this reason, projection exposure systems for EUV lithography are typically operated under vacuum conditions. Small amounts of hydrogen and/or other reactive gases, such as oxygen, can be added to the residual gas present in the vacuum environment -Have radiation.
  • a hydrogen plasma is typically formed in such a vacuum environment under the influence of the EUV radiation, i.e. activated hydrogen is formed in the form of hydrogen ions and hydrogen radicals.
  • the hydrogen ions or the hydrogen radicals produce an etching attack on exposed surfaces of components which are arranged in the vacuum environment.
  • the exposed surfaces can be, for example, exposed surface areas of a reflective optical element the surface exposed to the etching attack may contain silicon, for example.
  • the etching attack can lead to the formation of highly volatile (volatile) substances such as SiHs, SiH4 (silanes) on the surface, which is associated with a removal of the exposed surfaces and at the same time with the deposition of the volatile substances on optically used surfaces. This results in a loss of reflectivity or a degradation of the layer materials used there, possibly up to undercutting and large-area defects.
  • SiHs silicon-containing silicon
  • Atomic hydrogen can also penetrate into the exposed material and accumulate at defects or interfaces as molecular hydrogen that can no longer escape, which can also result in delamination.
  • the reflective coating in particular in the form of double layers of Mo/Si, can serve as a protective layer against the penetration of hydrogen in the surface area covered by the reflective coating, as long as the reflective coating is closed and is not changed, for example, by oxidation.
  • Reflecting optical elements for example in the form of mirrors for illumination optics of projection exposure systems, can have a structured surface in the form of a grid structure.
  • the lattice structure can serve as a spectral filter in order to filter out radiation in a wavelength range which is undesirable and which can be, for example, in the infrared or ultraviolet wavelength range. If the reflective coating is applied to such a structured surface, the problem arises that flanks may be formed there with a flank steepness that is so great that the reflective coating does not completely cover the structured surface during coating. so that gaps appear in the reflective coating which an etching attack can occur in an exposed surface area of the structured surface.
  • DE 102018 220629 A1 discloses a mirror for an illumination optics of a projection exposure system with a spectral filter in the form of a lattice structure.
  • the lattice structure has a maximum edge steepness in the range from 15° to 60°.
  • the lattice structure can be completely covered by a closed protective layer, which has a plurality of Si—Mo double layers and forms a reflective coating.
  • the low edge steepness of the grating structure improves the coverage of the grating structure or the structured surface with the protective layer and in this way increases the hydrogen stability of the reflective optical element.
  • WO 2013/113537 A2 describes a reflective optical element for reflecting EUV radiation, which has a substrate on which a multilayer stack is formed on at least one surface, which has a plurality of alternating material layers for reflecting EUV radiation having.
  • a spectral filter is formed on the surface in the form of a three-dimensional profile on a scale significantly larger than the wavelength of the EUV radiation.
  • the multilayer stack comprises a conformal coating stack formed on the substrate after formation of the three-dimensional profile.
  • magnetron sputtering which is usually used for applying multi-layer stacks, leads to a high surface roughness of the applied layers.
  • a conformal or isotropic coating process in the form of atomic layer deposition is therefore proposed as the coating process for applying the multi-layer stack, which produces essentially constant layer thicknesses along the three-dimensional profile.
  • the application of a reflective multi-layer coating, which can have more than 50 Mo-Si double layers, by atomic layer deposition is very complex.
  • the object of the invention is to specify a reflective optical element, an illumination optics, a projection exposure system and a method for forming a protective layer, which make it possible to protect the structured surface from an etching attack in an efficient manner.
  • an optical element of the type mentioned at the outset in which the reflective coating does not cover the structured surface in a closed manner and in which the reflective optical element has at least one (additional) protective layer which covers the structured surface in a closed manner.
  • the structured surface in particular the grid structure, has a maximum edge steepness of more than 60°, preferably more than 80°, in particular more than 90°.
  • the (maximum) edge steepness is measured here relative to a tangent to the (local) surface of the reflecting optical element (eg the surface of a substrate) or, in the case of a grating structure, in the area between two grating bars.
  • the application of the reflective coating in the form of a multi-layer coating generally cannot be true to the surface with such a high edge steepness.
  • the additional protective layer(s) which cover(s) the structured surface in a closed manner, the structured surface can nevertheless be efficiently protected against an etching attack.
  • flanks with a flank steepness of more than 90° i.e. an undercut flank, as can be formed with wet-chemical etching, for example.
  • the protective layer has a thickness of, for example, 100 nm or less, preferably 10 nm or less, particularly preferably 5 nm or less.
  • the protective layer In order to produce a closed protective layer with the edge steepness described above, it is typically necessary to apply it using a comparatively complex isotropic coating process. However, only a comparatively small thickness of the protective layer is required to protect the structured surface from an etching attack.
  • the reflective coating which generally has a significantly greater thickness, can be applied using a non-isotropic coating process. Such a coating method is less complex, but has the result that the reflective coating does not completely cover the structured surface.
  • the coating forms a multi-layer coating for reflecting EUV radiation.
  • Such a multilayer coating typically comprises a plurality of alternating layers of a material having a high refractive index at the operating wavelength and a material having a low refractive index at the operating wavelength.
  • the materials can be, for example, silicon and molybdenum, but other material combinations are also possible depending on the operating wavelength.
  • the protective layer is formed between the structured surface and the reflective coating.
  • the application of the protective layer below the reflective coating is favorable since in this case the protective layer produces practically no loss of reflectivity.
  • the protective layer itself can also be structured, for example in order to produce a sub-lattice structure or a further structuring of the lattice structure which is located under the protective layer.
  • a topcoat is applied to the reflective coating.
  • the cap layer serves to protect the underlying layers of the reflective coating from further environmental influences, for example from oxidation or from tin contamination, which are generated by an EUV radiation source.
  • the material of the cover layer can also be selected in such a way that contamination, in particular in the form of tin contamination, can be removed from the surface of the cover layer if necessary.
  • the cover layer generally does not cover the structured surface in a closed manner and is typically applied in a non-isotropic coating process.
  • the cover layer forms the protective layer, which completely covers the structured surface.
  • the cover layer is typically applied using an isotropic coating process and forms an overcoating that also covers the (possibly steep) flanks of the structured surface or the lattice structure in a closed manner.
  • the protective layer in the form of the cover layer can optionally be combined with a further protective layer, which is arranged between the reflective coating and the structured surface as described above.
  • the material of the protective or cover layer absorbs part of the EUV radiation and therefore reduces the reflectivity of the reflective optical element.
  • the cover layer can form a single layer, but it is also possible for the cover layer itself to form a multi-layer coating that has two or more layers made of different materials.
  • the structured surface is formed in a functional layer applied to a substrate and/or in the substrate.
  • the functional layer is typically easy to process (eg by machining, polishing, structuring by etching, ).
  • other functional layers can also be applied to the substrate in addition to the functional layer that is processed to form the structured surface.
  • this can involve one or more layers which enable processing to form the yoke of the reflecting optical element, for example by machining, polishing, etc.
  • the functional layer can also be an adhesion promoter layer or the like.
  • the substrate of the reflective optical element which has a significantly greater thickness than the functional layer(s), can also have the structured surface. It is also possible for the structured surface to be formed partially in the functional layer and partially in the substrate.
  • the substrate and/or the functional layer has at least one material selected from the group comprising: amorphous silicon (aSi), silicon (Si), nickel phosphorus (Ni: P), metals, in particular from Group titanium (Ti), platinum (Pt), gold (Au), aluminum (Al), nickel (Ni), copper (Cu), silver (Ag), tantalum (Ta), tungsten (W) and their alloys; Oxides, in particular from the group of silicon dioxide (SiC), aluminum oxide (AIO X ), titanium oxide (TiO x ), tantalum oxide (TaO x ), niobium oxide (NbO x ), zirconium oxide (ZrO x ) and combinations thereof (e.g. mixed oxides, ceramics, glasses , glass ceramics, composites). As described in DE 10 2018 220 629 A1 cited at the outset, these materials have proven particularly useful for the components of an EUV projection exposure system.
  • the protective layer has at least one material which is selected from the group comprising: metals, in particular copper (Cu), cobalt (Co), platinum (Pt), indium (Ir), palladium (Pd), ruthenium ( Ru), gold (Au), tungsten (W), ...
  • the protective layer can be formed from a single layer, but it is also possible for the protective layer itself to form a multi-layer coating that has two or more layers made of different materials.
  • the material or materials of the protective layer must meet several requirements: On the one hand, the protective layer should prevent the diffusion of molecular hydrogen (H2), hydrogen ions (H + ) and hydrogen radicals (H*) through the (thin) protective layer as far as possible prevent completely. On the other hand, the protective layer or its material should not react chemically with H2, H + , H* or with tin. Also should Protective layer have a high temperature resistance and a high resistance to reduction and oxidation, a high EUV resistance and a high resistance to cleaning processes, in particular for the removal of deposits caused by operation in the system (e.g. tin).
  • the protective layer should not cause any deterioration in the roughness of the substrate or the functional layer to which it is applied. It is also advantageous if the protective layer can be removed in a comparatively simple manner during a so-called refurbishment process, in which an old coating is removed and replaced by a new coating, or is not attacked or disadvantageously roughened by such a process.
  • the materials listed above meet most of the requirements listed above.
  • the reflecting optical element is designed as a collector mirror for an illumination optics of a projection exposure system.
  • a collector mirror can have, for example, one or more ellipsoidal and/or hyperboloidal reflection surfaces which correspond to the surface with the reflective coating.
  • the reflection surface of the collector mirror can be exposed to illumination radiation in grazing incidence (Grazing Incidence, Gl), i.e. with angles of incidence greater than 45°, or in normal incidence (Normal Incidence, NI), i.e. with angles of incidence smaller than 45°.
  • Gl grazing Incidence
  • NI normal incidence
  • the collector mirror typically has a structured surface in the form of a grid structure, which serves as a spectral filter in order to suppress stray light, ie radiation at wavelengths outside the EUV wavelength range, for example in the infrared or ultraviolet wavelength range.
  • the reflecting optical element does not necessarily have to be in the form of a collector mirror, but that it can also be something else can act reflective optical element having a structured surface.
  • One aspect of the invention relates to illumination optics for a projection exposure system, comprising: at least one reflective optical element, which is designed as described above.
  • the reflecting optical element can be, for example, the collector mirror described above.
  • a projection exposure system for microlithography in particular for EUV lithography, comprising: illumination optics, which are designed as described above, for transferring illumination radiation from a radiation source to a reticle with structures to be imaged, and projection optics for imaging of the structures of the reticle onto a wafer.
  • the invention also relates to a method for forming a protective layer on a reflective optical element which is designed as described above, the method comprising: applying the protective layer to the structured surface or to the reflective coating using an isotropic coating method.
  • a closed protective layer can be applied with the aid of an isotropic coating method even in the case of a structured surface which has flanks with a high flank steepness.
  • the reflective coating can be applied using a non-isotropic coating process, for example a PVD coating process such as magnetron sputtering.
  • a non-isotropic coating method for applying the reflective coating is advantageous since this usually has a (significantly) greater thickness than the protective layer.
  • the isotropic coating method is selected from the group comprising: chemical vapor deposition (CVD), in particular atomic layer deposition (ALD), or physical vapor deposition (PVD).
  • the coating is applied by PVD, a special, oriented geometry is typically required, which reduces the actual anisotropy of these processes.
  • Combinations of several material sources are possible here, which can be arranged in a tilted manner, for example.
  • the coating rates can be controlled by shadowing, which suppresses certain impact angles.
  • a tilting or pivoting movement of the mirror to be coated is possible.
  • FIG. 1 shows a schematic meridional section of a projection exposure system for E UV lithography
  • FIGS. 5a, b show a schematic representation analogous to FIGS. 5a, b, in which the protective layer is applied to the reflective coating and covers the lattice structure in a closed manner
  • FIG. 7 shows a schematic representation analogous to FIG. 5a, in which a cover layer that does not cover the lattice structure in a closed manner is applied to the reflective coating.
  • the wafer holder 14 can be displaced in particular along the y-direction via a wafer displacement drive 15 .
  • the displacement of the reticle 7 via the reticle displacement drive 9 on the one hand and the wafer 13 on the other hand via the wafer displacement drive 15 can be synchronized with one another.
  • the intermediate focus plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector mirror 17, and the illumination optics 4.
  • the illumination optics 4 thus forms a double-faceted system.
  • This basic principle is also known as the Fly's Eye Integrator.
  • the individual first facets 21 are imaged in the object field 5 with the aid of the second facet mirror 22 .
  • the second facet mirror 22 is the last beam-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path in front of the object field 5.
  • the projection optics 10 includes a plurality of mirrors Mi, which are numbered consecutively according to their arrangement in the beam path of the projection exposure system 1 .
  • the projection optics 10 includes six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or another number of mirrors Mi are also possible.
  • the penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16.
  • the projection optics 10 are doubly obscured optics.
  • the projection optics 10 has an image-side numerical aperture which is greater than 0.5 and which can also be greater than 0.6 and which can be 0.7 or 0.75, for example.
  • the functional layer 25 is selectively etched using the structuring layer 26 as an etching mask the structured surface 25a forms on the functional layer 25.
  • the structured surface 25a forms the grating structure 29, the geometry of which is selected in such a way that it serves as a spectral filter and suppresses stray light at wavelengths in a given wavelength range.
  • FIG. 3a shows a detail of the structured surface 25a shown in dashed lines in FIG. 2 after the structuring layer 26 has been removed. Furrows 34 are formed between the grid bars 31 and have a bottom 35 .
  • the structured functional layer 25 with the lattice structure 29 is formed on a substrate 30 of the collector mirror 17 .
  • the structured surface 25a can also be formed in the substrate 30 or the structured surface 25 can be formed partly in the functional layer 25 and partly in the substrate 30, as is shown in DE 10 2018220 629 A1.
  • the functional layer 25 and the substrate 30 have at least one material that can be processed well or structured well by etching.
  • the material of the functional layer 25 or of the substrate 30 can be, for example, amorphous silicon (aSi), silicon (Si), nickel phosphorus, metals, in particular from the group titanium (Ti), platinum (Pt), gold (Au) , Aluminum (AI), Nickel (Ni), Copper (Cu), Silver (Ag), Tantalum (Ta), Tungsten (W) , ...
  • Oxides in particular from the group of silicon dioxide (SiO2), aluminum oxide (AIO X ), titanium oxide (TiO x ), tantalum oxide (TaO x ), niobium oxide (NbO x ), zirconium oxide (ZrO x ) and combinations thereof (e.g. mixed oxides, ceramics, glasses , glass ceramics, composites).
  • the grid bars 31 shown in FIG. 3a each have flanks 33 with a flank steepness a of 90°.
  • the edge steepness a is measured in relation to a local tangential plane which corresponds to the upper side of the substrate 30 .
  • the flank steepness a of the flank 33 can also be measured against a tangential plane which corresponds to the bottom 35 of the groove 34 which is adjacent to the flank 33 .
  • the edge steepness a is measured in relation to a local tangential plane, since the surface of the substrate 30 or of the collector mirror 17 is not flat, but rather generally has an ellipsoidal and/or hyperboloidal geometry, as described above.
  • a protective layer 37 is formed between the structured surface 25a and the reflective coating 36 in the examples shown in FIGS. 5a, b.
  • the protective layer 37 covers the structured surface 25a in a closed manner, i.e. over the entire surface and without gaps in the area of the flanks 33.
  • the protective layer 37 is applied or deposited using an isotropic coating method.
  • the isotropic coating process is atomic layer deposition, but another isotropic CVD coating process or a PVD coating process with a suitably selected, oriented geometry can also be used for this purpose, which reflects the typically existing anisotropy of the PVD process reduced.
  • combinations of several material sources are possible, which can be arranged tilted, for example.
  • the coating rates can be controlled by shadowing, which suppresses certain impact angles.
  • a tilting or pivoting movement of the optical element 17 to be coated is possible.
  • oxides in particular from the group aluminum oxide (AlOx), zirconium oxide (ZrOx), titanium oxide (TiOx), niobium oxide (NbOx), Tantalum oxide (TaOx), hafnium oxide (HfOx), chromium oxide (CrOx), carbides, borides, nitrides, silicides and combinations thereof (e.g. mixed oxides, ceramics, glasses, glass ceramics, composites).
  • AlOx aluminum oxide
  • ZrOx zirconium oxide
  • TiOx titanium oxide
  • NbOx niobium oxide
  • Tantalum oxide TiOx
  • hafnium oxide HfOx
  • CrOx chromium oxide
  • carbides borides, nitrides, silicides and combinations thereof (e.g. mixed oxides, ceramics, glasses, glass ceramics, composites).
  • the protective layer 37 forms a cover layer which is applied to the reflective multi-layer coating 36 using an isotropic coating process.
  • the protective layer 37 covers both the reflective coating 36 and a partial area of the structured surface 25a, which is not covered by the reflective coating 36, over the full area and in a closed manner.
  • the protective layer 37 also has a small thickness d of less than approximately 10 nm and is formed from a material or a combination of materials which has comparatively low absorption for EUV radiation 16 . In this way it can be ensured that the protective layer 37 does not reduce the reflectivity of the collector mirror 17 too much.
  • FIG. 7 shows an example of a collector mirror 17 in which the protective layer 37 is formed between the structured surface 25a and the reflective coating 36 as in FIGS. 5a, b.
  • a cover layer 38 is applied to the reflective coating 36 .
  • the cover layer 38 shown in FIG. 7 does not form a complete protective layer, since it does not cover the structured surface 25a in a closed manner, but rather has gaps, as is also the case with the reflective coating 36.
  • the cover layer 38 can be formed, for example, from one of the materials described above in connection with the protective layer 37 .
  • a cover layer 38 can also be applied to the reflective coating 36 in the examples shown in FIGS. 5a, b.
  • the cover layer 38 can be applied by an isotropic coating process, as shown in FIG. 6, or by an anisotropic coating process, as shown in FIG. It goes without saying that the protective layer 37 can be applied not only to the collector mirror 17 but also to other structured reflecting optical elements of the projection exposure system 1 in order to protect them from the etching attack of a hydrogen plasma.
  • the protective layer can also be used in reflective optical elements that are designed to reflect radiation at wavelengths other than the EUV wavelength range.
  • the protective layer 37 can also serve to protect the structured surface 25a from an etching attack by chemical elements other than hydrogen. In this case, the materials from which the protective layer 37 is formed should be matched to the chemical elements from which the structured surface 25a is to be protected.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Public Health (AREA)
  • Environmental & Geological Engineering (AREA)
  • Epidemiology (AREA)
  • Health & Medical Sciences (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

L'invention concerne un élément optique réfléchissant (17), en particulier destiné à une unité d'éclairage optique d'un système d'éclairage par projection, comprenant : une surface structurée (25a) qui forme de préférence une structure de grille ; et un revêtement réfléchissant (36) qui est appliqué sur la surface structurée (25a). Le revêtement réfléchissant (36) recouvre certaines parties de la surface structurée (25a), et l'élément optique réfléchissant (17) comprend au moins une couche de protection (37) qui recouvre l'ensemble de la surface structurée (25a). L'invention concerne également une unité d'éclairage optique destinée à un système d'éclairage par projection, comprenant un tel élément optique réfléchissant (17) ou plus, un système d'éclairage par projection comprenant une telle unité d'éclairage optique, et un procédé de fabrication d'une couche de protection (37) sur un tel élément optique réfléchissant (17).
EP21743436.4A 2020-08-20 2021-07-12 Élément optique réfléchissant, unité d'éclairage optique, système d'éclairage par projection et procédé de fabrication de couche de protection Pending EP4200879A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102020210553.7A DE102020210553A1 (de) 2020-08-20 2020-08-20 Reflektierendes optisches Element, Beleuchtungsoptik, Projektionsbelichtungsanlage und Verfahren zum Bilden einer Schutzschicht
PCT/EP2021/069248 WO2022037846A1 (fr) 2020-08-20 2021-07-12 Élément optique réfléchissant, unité d'éclairage optique, système d'éclairage par projection et procédé de fabrication de couche de protection

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EP4200879A1 true EP4200879A1 (fr) 2023-06-28

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US (1) US20230205090A1 (fr)
EP (1) EP4200879A1 (fr)
JP (1) JP2023538620A (fr)
DE (1) DE102020210553A1 (fr)
WO (1) WO2022037846A1 (fr)

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Publication number Priority date Publication date Assignee Title
US6607862B2 (en) * 2001-08-24 2003-08-19 Intel Corporation Damascene extreme ultraviolet lithography alternative phase shift photomask and method of making
DE10223113B4 (de) 2002-05-21 2007-09-13 Infineon Technologies Ag Verfahren zur Herstellung einer photolithographischen Maske
DE102008000990B3 (de) 2008-04-04 2009-11-05 Carl Zeiss Smt Ag Vorrichtung zur mikrolithographischen Projektionsbelichtung und Verfahren zum Prüfen einer derartigen Vorrichtung
NL2002545C2 (nl) 2009-02-20 2010-08-24 Univ Twente Werkwijze voor het splitsen van een bundel met elektromagnetische straling met golflengtes in het extreem ultraviolet (euv) en het infrarood (ir) golflengtegebied en optisch tralie en optische inrichting daarvoor.
KR20120101983A (ko) * 2009-06-30 2012-09-17 에이에스엠엘 네델란즈 비.브이. 스펙트럼 퓨리티 필터, 리소그래피 장치, 및 스펙트럼 퓨리티 필터를 제조하는 방법
WO2013113537A2 (fr) 2012-01-30 2013-08-08 Asml Netherlands B.V. Elément optique, appareil lithographique comprenant cet élément, et procédé de fabrication d'un élément optique
US9435921B2 (en) 2013-08-02 2016-09-06 Globalfoundries Inc. Blazed grating spectral purity filter and methods of making such a filter
RU2555168C1 (ru) * 2014-02-17 2015-07-10 Сергей Анатольевич Смирнов Изделие - стекло со смешанным декоративным покрытием и способ его получения
WO2016131069A2 (fr) 2015-12-11 2016-08-18 Johnson Kenneth Carlisle Source de lumière euv incluant un filtre de pureté spectrale et un recyclage d'énergie
JP2017161872A (ja) * 2016-03-11 2017-09-14 凸版印刷株式会社 表示体及び情報印刷物
DE102018220629A1 (de) 2018-11-29 2020-06-04 Carl Zeiss Smt Gmbh Spiegel für eine Beleuchtungsoptik einer Projektionsbelichtungsanlage mit einem Spektralfilter in Form einer Gitterstruktur und Verfahren zur Herstellung eines Spektralfilters in Form einer Gitterstruktur auf einem Spiegel

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WO2022037846A1 (fr) 2022-02-24
JP2023538620A (ja) 2023-09-08
US20230205090A1 (en) 2023-06-29
DE102020210553A1 (de) 2022-03-24

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