US20170176741A1 - Mirror element, in particular for a microlithographic projection exposure apparatus - Google Patents

Mirror element, in particular for a microlithographic projection exposure apparatus Download PDF

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Publication number
US20170176741A1
US20170176741A1 US15/381,910 US201615381910A US2017176741A1 US 20170176741 A1 US20170176741 A1 US 20170176741A1 US 201615381910 A US201615381910 A US 201615381910A US 2017176741 A1 US2017176741 A1 US 2017176741A1
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Prior art keywords
mirror
mirror element
substrate
layer
layer stack
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Hartmut Enkisch
Martin Hermann
Christoph Nottbohm
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Carl Zeiss SMT GmbH
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Carl Zeiss SMT GmbH
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Priority to US15/837,932 priority Critical patent/US10598921B2/en
Assigned to CARL ZEISS SMT GMBH reassignment CARL ZEISS SMT GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ENKISCH, HARTMUT, HERMANN, MARTIN, NOTTBOHM, CHRISTOPH
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
    • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/0891—Ultraviolet [UV] mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/09—Multifaceted or polygonal mirrors, e.g. polygonal scanning mirrors; Fresnel mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/10—Mirrors with curved faces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/18—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors
    • G02B7/181—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
    • 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
    • G03F7/70075—Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection
    • 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
    • G03F7/70091—Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
    • G03F7/70116—Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
    • 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
    • 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
    • G03F7/70216—Mask projection systems
    • G03F7/70316—Details of optical elements, e.g. of Bragg reflectors, extreme ultraviolet [EUV] multilayer or bilayer mirrors or 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
    • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
    • G03F7/70858—Environment aspects, e.g. pressure of beam-path gas, temperature
    • G03F7/70883—Environment aspects, e.g. pressure of beam-path gas, temperature of optical system
    • G03F7/70891—Temperature
    • 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

Definitions

  • the invention relates to a mirror element, in particular for a microlithographic projection exposure apparatus.
  • Microlithography is used for producing microstructured components, such as integrated circuits or LCDs, for example.
  • the microlithography process is carried out in a so-called projection exposure apparatus comprising an illumination device and a projection lens.
  • the image of a mask (reticle) illuminated by the illumination device is in this case projected by the projection lens onto a substrate (for example a silicon wafer) coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection lens, in order to transfer the mask structure to the light-sensitive coating of the substrate.
  • mirrors are used as optical components for the imaging process.
  • facet mirrors in the form of field facet mirrors and pupil facet mirrors as focusing components
  • facet mirrors are constructed from a multiplicity of individual mirrors or mirror facets, which may be designed to each be tiltable by way of flexure bearings for the purposes of adjusting, or else for realizing, specific illumination angle distributions.
  • These mirror facets may comprise a plurality of micromirrors in turn.
  • mirror arrangements which comprise a multiplicity of mutually independently adjustable mirror elements in an illumination device of a microlithographic projection exposure apparatus, designed for operation at wavelengths in the very ultraviolet (VUV) range, for adjusting defined illumination settings (i.e. intensity distributions in a pupil plane of the illumination device) is also known, for example, from WO 2005/026843 A2.
  • a known approach to this end consists of using the mechanical tension generated when applying a layer stack, including the reflection layer system, onto a substrate and the bending force exerted on the substrate by the layer stack as a result thereof in a targeted manner when manufacturing the respective mirror element in order to generate a setpoint curvature of the mirror element—and hence a desired finite refractive power of the mirror element (wherein the substrate has a curvature deviating from the setpoint curvature of the mirror element prior to the formation of the layer stack).
  • a problem occurring in practice is that the mirror elements are exposed to temperature changes (both during the commissioning and during the subsequent running operation of the respective optical system).
  • this produces an unwanted change in the curvature or refractive power of the respective mirror element and consequently may lead to a deterioration in the optical properties of the optical system comprising the mirror element.
  • a mirror element according to the invention in particular for a microlithographic projection exposure apparatus, comprises:
  • the layer stack has at least one reflection layer system
  • a curvature of the mirror element is generated on the basis of a setpoint curvature for a predetermined operating temperature by a non-vanishing bending force exerted by the layer stack;
  • the invention initially proceeds from the principle of using the mechanical tension generated when applying a layer stack, including the reflection layer system, onto a substrate and the bending force exerted on the substrate by the layer stack as a result thereof in a targeted manner in order to generate a setpoint curvature or refractive power of the mirror element (wherein the substrate has a curvature deviating from the setpoint curvature of the mirror element prior to the formation of the layer stack).
  • the invention is based on the concept of designing the (overall) system made of substrate and layer stack in such a way that there is no significant variation in the curvature of the mirror element and hence no significant variation in the refractive power thereof any more, even in the case of a temperature change occurring at least within a restricted temperature interval, i.e. that an unwanted bimetallic effect is largely avoided at least over a restricted temperature range.
  • the generated curvature varies by no more than 1%, in particular by no more than 0.1%, over a temperature interval ( ⁇ T) of at least 10 K.
  • the mirror element comprises a compensation layer which at least partly compensates a variation of the bending force exerted by the layer stack accompanying a change in temperature occurring within the temperature interval in terms of the influence of said bending force on the curvature of the mirror element.
  • the compensation of the bimetallic effect according to the invention is therefore carried out by virtue of an additional layer being provided to this end, said layer—depending on the specific placement of this additional layer relative to the substrate and the layer stack in the overall structure—just exerting the bending force on the substrate which, in comparison with the bending force of the layer stack additionally induced by temperature change, is of the same magnitude or of the same magnitude with opposite sign such that, in the ideal case, a thermally induced change in the bending force of the layer stack is compensated and no thermally induced change in the curvature or refractive power occurs any more in the overall system or in the mirror element.
  • the mirror element comprises an equalization layer which reduces a transfer of mechanical tension between the layer stack and the substrate compared to an analogous design without the equalization layer.
  • the compensation of the bimetallic effect according to the invention therefore occurs by virtue of mechanical decoupling between the layer stack and substrate being provided by way of a “soft” equalization layer.
  • the mirror element is embodied in such a way that a mean coefficient of thermal expansion of the substrate has a first value and a mean coefficient of thermal expansion of the layer stack has a second value, wherein the first value and the second value correspond to within ⁇ 10%, in particular to within ⁇ 3%, more particularly to within ⁇ 1%, in each case in relation to the larger one of the two values.
  • the compensation of the bimetallic effect according to the invention therefore occurs by virtue of adapting the configuration of the substrate in view of the material used in the substrate or the materials used in the substrate to the configuration of the layer stack in respect of the respective mean coefficient of thermal expansion.
  • the substrate is produced from at least two different materials.
  • the invention is not restricted to the application of the principle, set forth at the outset, of using a bending force exerted by the layer stack on the substrate in a targeted manner in order to generate a setpoint curvature or refractive power of the mirror element (wherein the substrate has a curvature deviating from the setpoint curvature of the mirror element prior to forming the layer stack).
  • the invention may also be applied to mirror elements in which the substrate is manufactured from the outset with substantially a setpoint curvature, with in this case a bending force exerted by the layer stack on the substrate (for example due to a comparatively large substrate thickness) being only very small.
  • the invention therefore further relates to a mirror element, in particular for a microlithographic projection exposure apparatus, comprising:
  • the layer stack has at least one reflection layer system
  • an equalization layer which reduces a transfer of mechanical tension between the layer stack and the substrate compared to an analogous design without the equalization layer.
  • the mirror element comprises an additional tension-inducing layer.
  • This additional tension-inducing layer may be configured in a targeted manner in such a way that, overall, a desired mechanical tension or a desired bending force exerted by the layer stack on the substrate is achieved.
  • the mirror element is a mirror element of a mirror arrangement composed of a plurality of mirror elements.
  • these mirror elements may be tiltable independently of one another.
  • the invention is not restricted to certain dimensions of the respective mirror elements.
  • the mirror elements may be so-called MEMS components, the dimensions of which may, merely by way of example, lie in the region of 50 ⁇ m thickness and 1 mm edge length, or else comparatively macroscopic mirror elements, for example of a facet mirror, with e.g. several millimetres (mm) thickness and e.g. 100 mm edge length.
  • MEMS components the dimensions of which may, merely by way of example, lie in the region of 50 ⁇ m thickness and 1 mm edge length, or else comparatively macroscopic mirror elements, for example of a facet mirror, with e.g. several millimetres (mm) thickness and e.g. 100 mm edge length.
  • the mirror arrangement is a facet mirror, in particular a field facet mirror or a pupil facet mirror.
  • the mirror element is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm.
  • the invention is not restricted thereto, and so the mirror element may also be designed for a wavelength in the VUV range, in particular a wavelength of less than 200 nm, in further applications.
  • the mirror element is a mirror element of a microlithographic projection exposure apparatus.
  • the invention is not restricted thereto; rather, it is also realizable for example in measurement constructions which, in particular, may be designed for operation in EUV.
  • the invention furthermore relates to an optical system of a microlithographic projection exposure apparatus, in particular an illumination device or a projection lens, and to a microlithographic projection exposure apparatus.
  • FIGS. 1A-1E show schematic illustrations for explaining various embodiments using respectively different materials and/or configurations in the substrate of a mirror element according to the invention
  • FIGS. 2A-2C show schematic illustrations for explaining various embodiments of a mirror element according to the invention using respective additional layers
  • FIGS. 3A-3M show schematic illustrations for explaining various embodiments of a mirror element according to the invention using respective additional tension-inducing layers
  • FIGS. 4A-4C show schematic illustrations for explaining various embodiments of a mirror element according to the invention using an equalization layer ( FIG. 4A ) or an additional tension-inducing layer ( FIG. 4B and FIG. 4C );
  • FIGS. 5A-5B show schematic illustrations for explaining the effect of mechanical tension resulting in curvature of substrates following application of respective layer systems.
  • FIG. 6 shows a schematic illustration for explaining a representative construction of a microlithographic projection exposure apparatus designed for operation in EUV.
  • FIGS. 1-5 Various embodiments of a mirror element according to the invention are initially described below with reference to FIGS. 1-5 .
  • the produced mirror elements may be e.g. mirror elements or micromirrors of a mirror arrangement in the form of a field facet mirror (without the invention being restricted thereto), wherein the individual mirror elements may have identical or else differing curvatures or refractive powers.
  • a layer stack which has a reflection layer system (e.g. as a multiple layer system made of molybdenum and silicon layers), is applied onto a respective substrate.
  • the mirror substrate material may be, for example, silicon (Si) or quartz glass doped with titanium dioxide (TiO 2 ), with examples of materials that are usable being those sold under the trade names ULE® (by Corning Inc.) or Zerodur® (by Schott AG).
  • the mirror substrate material may also comprise germanium (Ge), diamond, gallium arsenide (GaAs), gallium nitride (GaN), gallium antimonide (GaSb), gallium phosphide (GaP), Al 2 O 3 , indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), calcium fluoride (CaF 2 ), zinc oxide (ZnO) or silicon carbide (SiC).
  • germanium germanium
  • diamond gallium arsenide
  • GaN gallium nitride
  • GaSb gallium antimonide
  • GaP gallium phosphide
  • Al 2 O 3 Al 2 O 3
  • InP indium arsenide
  • InAs indium antimonide
  • InSb calcium fluoride
  • ZnO zinc oxide
  • SiC silicon carbide
  • further functional layers such as e.g. a capping layer (“cap
  • a bending force of the layer stack different from zero may be exerted on the substrate in each case when forming the layer stack comprising the reflection layer system by way of a suitable adjustment of the coating parameters and/or the parameters of a post-treatment and the mechanical tension generated thereby.
  • the mechanical tension when forming the respective layer stack may be set in a manner known per se by virtue of materials and thickness ratios (e.g. the ratio of the absorber ply thickness to the overall thickness of a period, wherein this thickness ratio is also referred to as ⁇ ) being set in the desired manner in the reflection layer system in particular.
  • the procedure when setting a mechanical tension is known to a person skilled in the art, for example, from DE 10 2008 042 212 A1.
  • the mechanical tension may also be set when applying the respective layer stack by oxygen doping or the addition of oxygen during the coating, as is known to a person skilled in the art from DE 10 2011 003 357 A1.
  • This mechanical tension generated on the substrate during the formation of the layer stack comprising the reflection layer system leads to the curvature of the substrate changing in comparison with the original curvature which was present in the state prior to the coating.
  • Either said original curvature of the substrate in the state prior to the coating may equal zero (i.e. the substrate is plane prior to the coating) or the original curvature may correspond to a finite curvature (e.g. a curvature coating) not yet corresponding to the ssetpoint curvature of the completed mirror element.
  • a plurality of mirror elements with the same curvature or refractive power can be produced by virtue of plane (mirror) substrates 511 , 512 , . . .
  • the respective substrates 513 , 514 , . . . can also have a finite curvature in the initial state (prior to the coating), said finite curvature not yet corresponding to the ultimately desired curvature.
  • This substrate curvature is then changed by the mechanical tension generated when applying the layer stack or by the exerted bending force. Specifically, a convex curvature of the substrates 513 , 514 , . . . present in the initial state prior to the coating in the example of FIG. 5B is brought to zero; that is to say, a plane geometry of the completed mirror elements is ultimately generated.
  • the compensation according to the invention of the “bimetallic effect”, i.e. the compensation of a variation of the bending force exerted by the layer stack accompanying a temperature change, in terms of the influence thereof on the curvature of the mirror element, is obtained by suitable adaptation of the configuration of the substrate to the configuration of the layer stack, in particular with regard to the respectively present mean coefficient of thermal expansion.
  • the substrate in a respective mirror element 110 a - 110 e is designed in view of the material used in the substrate or in view of the materials used in the substrate. This is done in such a way that the mean coefficient of thermal expansion of the substrate substantially corresponds in terms of the value thereof to the mean coefficient of thermal expansion of the layer stack (preferably to within ⁇ 3% in relation to the larger of the two values).
  • the above-described adaptation of the substrate (in each case denoted by 111 , 112 , 113 , 114 and 115 in FIGS. 1A-1E ) to the layer stack (in each case denoted by 121 , 122 , 123 , 124 and 125 in FIGS. 1A-1E ) may be carried out by virtue of the fact that the substrate material already has the suitable mean coefficient of thermal expansion substantially corresponding to the value in the respective layer stack, as illustrated in FIG. 1A for the case of a homogeneous configuration of the substrate.
  • this correspondence on the part of the substrate can be achieved by doping with a further material with a deviating coefficient of thermal expansion, as illustrated in FIG. 1B .
  • the correspondence can be achieved through layers ( FIG. 1C ) or columns ( FIG. 1D ) of a further material with a deviating coefficient of thermal expansion.
  • FIG. 1E shows a schematic illustration of a further embodiment, in which the mixture of different substrate materials selected for the substrate 115 is distributed among a plurality of layers such that, as a result, a gradient emerges in the coefficient of thermal expansion.
  • the invention therefore contains the concept of appropriately selecting the coefficient of thermal expansion of the substrate (as “free” parameter) in the case of a predetermined value of the coefficient of thermal expansion for the layer stack in order, as a result, to obtain the desired compensation effect.
  • the substrate is once again initially denoted by 211 , 212 or 213 and the layer stack (which comprises a reflection layer system and, optionally, further functional layers) is denoted by 221 , 222 or 223 .
  • the respective mirror element has a compensation layer 231 , 232 or 233 which serves to at least partly compensate the variation of the bending force exerted by the layer stack 221 , 222 or 223 accompanying a temperature change, in terms of the influence thereof on the curvature of the respective mirror element 210 a, 210 b or 210 c.
  • the compensation layer 231 is arranged between substrate 211 and layer stack 221 in accordance with FIG. 2A .
  • the compensation layer 231 is configured in such a way that the variation of the bending force exerted by the compensation layer 231 accompanying a temperature change within a temperature interval of e.g. at least 10 K is just equal in terms of magnitude but with opposite sign to the change of the bending force on the part of the layer stack 221 which is thermally induced by this temperature change.
  • a temperature interval of e.g. at least 10 K e.g. at least 10 K
  • t f1 and t f2 each denote the thicknesses of layer stack 221 and compensation layer 231 and wherein, in each case, a correspondence of the biaxial moduli or Poisson numbers of substrate 211 , layer stack 221 and compensation layer 231 was assumed.
  • the compensation layer 231 may be produced from silicon dioxide (SiO 2 ) with a coefficient of thermal expansion of 0.55*10 ⁇ 6 K ⁇ 1 , wherein the thickness of the compensation layer 231 in this case has an ideal value of 585 nm.
  • the invention therefore contains the concept of selecting the corresponding parameters of the compensation layer with a corresponding fit when proceeding from predetermined values for the coefficient of thermal expansion a of the substrate and of the layer stack and for the thickness of the layer stack in order, as a result, to obtain the desired compensation effect.
  • the introduction of the compensation layer facilitates achieving the desired compensation effect by the targeted configuration of the compensation layer (in respect of material and thickness) while maintaining the predetermined parameters in Equation (1), namely ⁇ Substrate , ⁇ layer stack and t f1 .
  • the compensation layer 232 may also be arranged on the side of the substrate 212 facing away from the layer stack 222 .
  • the bending force of the compensation layer 232 which is thermally induced by the above-described temperature change within a specific temperature interval is preferably ideally equal to the bending force exerted by the layer stack 222 in terms of magnitude and sign, i.e. the following applies:
  • this may be achieved by a compensation layer 232 made of aluminium (Al) with a coefficient of thermal expansion of 23*10 ⁇ 6 K ⁇ 1 in the case of an ideal thickness of the compensation layer 232 of 59 nm.
  • the compensation layer 233 may further also be arranged within the substrate 213 (i.e. neither on the upper nor lower side thereof).
  • an additional tension-inducing layer may be provided, the latter being configured in a targeted manner such that, as a result, a desired mechanical tension or a desired bending force exerted by the layer stack on the substrate is achieved.
  • the substrate is respectively denoted by 311 a , 311 b , . . .
  • the layer stack is respectively denoted by 321 a , 321 b , . . .
  • the optionally additionally present compensation layer is respectively denoted by 351 b, 351 c , . . . .
  • an additional tension-inducing layer 351 b , 351 c , . . . is provided in each case in the remaining embodiments in accordance with FIGS. 3B-3G , FIGS. 31-3J and FIGS. 3L-3M , wherein the variants emerging from the embodiments described above on the basis of FIGS. 2A-2C are schematically presented in detail.
  • FIG. 4A shows a further embodiment of the invention, in which the compensation of the bimetallic effect according to the invention is achieved by virtue of an equalization layer 441 being present, which reduces a transfer of mechanical tension between the substrate 411 and the layer stack 421 (such that the equalization layer 441 in this respect causes mechanical decoupling between the substrate 411 and layer stack 421 ).
  • FIG. 4B and FIG. 4C show further exemplary embodiments in which, analogous to FIGS. 3A-3M , an additional tension-inducing layer 452 or 453 is provided.
  • FIG. 6 shows a schematic illustration of one exemplary projection exposure apparatus which is designed for operation in the EUV range and in which the present invention may be realized.
  • an illumination device in a projection exposure apparatus 600 designed for EUV radiation comprises a field facet mirror 603 and a pupil facet mirror 604 .
  • the light from a light source unit comprising a plasma light source 601 and a collector mirror 602 is directed onto the field facet mirror 603 .
  • a first telescope mirror 605 and a second telescope mirror 606 are arranged in the light path downstream of the pupil facet mirror 604 .
  • a deflection mirror 607 is arranged downstream in the light path, said deflection mirror directing the radiation that is incident on it onto an object field in the object plane of a projection lens comprising six mirrors 651 - 656 .
  • a reflective structure-bearing mask 621 Arranged on a mask stage 620 at the location of the object field is a reflective structure-bearing mask 621 , which with the aid of the projection lens is imaged into an image plane, in which there is a substrate 661 coated with a light-sensitive layer (photoresist) on a wafer stage 660 .
  • a light-sensitive layer photoresist
  • the method according to the invention is applicable in a particularly advantageous manner to the manufacture of the pupil facet mirror 603 or of the pupil facet mirror 604 from FIG. 6 ; further particularly if the individual field facets of the field facet mirror 603 or the individual pupil facets of the pupil facet mirror 604 in turn are composed of individual mirror elements or micromirrors.

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US15/381,910 2015-12-16 2016-12-16 Mirror element, in particular for a microlithographic projection exposure apparatus Abandoned US20170176741A1 (en)

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US12498541B2 (en) * 2021-01-11 2025-12-16 Carl Zeiss Smt Gmbh Assembly having a decoupling joint for mechanically mounting an element

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DE102023205340A1 (de) 2023-06-07 2024-12-12 Carl Zeiss Smt Gmbh Verfahren zum Herstellen eines optischen Elements, sowie optisches Element und Beschichtungsanlage
DE102023210486A1 (de) 2023-10-24 2025-04-24 Carl Zeiss Smt Gmbh Optisches Element und EUV-Lithographiesystem
DE102024210151A1 (de) 2024-10-21 2026-04-23 Carl Zeiss Smt Gmbh Mikrospiegelelement und mikro-elektro-mechanisches System mit Mikrospiegelelement

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Publication number Priority date Publication date Assignee Title
WO2020131132A1 (en) * 2018-12-21 2020-06-25 Didi Research America, Llc Micromachined mirror assembly having multiple coating layers
US12498541B2 (en) * 2021-01-11 2025-12-16 Carl Zeiss Smt Gmbh Assembly having a decoupling joint for mechanically mounting an element

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JP2017126062A (ja) 2017-07-20
DE102015225510A1 (de) 2017-01-12
US10598921B2 (en) 2020-03-24
JP6875846B2 (ja) 2021-05-26
US20180101002A1 (en) 2018-04-12

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