WO2016087092A1 - Correction de surface sur des éléments optiques réfléchissants et revêtus - Google Patents

Correction de surface sur des éléments optiques réfléchissants et revêtus Download PDF

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Publication number
WO2016087092A1
WO2016087092A1 PCT/EP2015/073153 EP2015073153W WO2016087092A1 WO 2016087092 A1 WO2016087092 A1 WO 2016087092A1 EP 2015073153 W EP2015073153 W EP 2015073153W WO 2016087092 A1 WO2016087092 A1 WO 2016087092A1
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WO
WIPO (PCT)
Prior art keywords
deformable layer
optical element
magnetic
reflective optical
shape
Prior art date
Application number
PCT/EP2015/073153
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German (de)
English (en)
Inventor
Franz-Josef Stickel
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
Priority to CN201580073765.0A priority Critical patent/CN107111015A/zh
Priority to KR1020177017775A priority patent/KR20170088975A/ko
Publication of WO2016087092A1 publication Critical patent/WO2016087092A1/fr

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Classifications

    • 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
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
    • G02B27/0068—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration having means for controlling the degree of correction, e.g. using phase modulators, movable 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
    • G03F7/70258—Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
    • G03F7/70266—Adaptive optics, e.g. deformable optical elements for wavefront control, e.g. for aberration adjustment or correction
    • 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

Definitions

  • the invention relates to a method for correcting a surface shape of a reflective optical element comprising a substrate and a reflective coating.
  • the invention also relates to a method for
  • Microlithography projection exposure equipment is used for the production of microstructured components by means of a photolithographic
  • a structure-bearing mask the so-called reticle
  • a photosensitive layer with the aid of a projection objective.
  • the minimum structure width which can be imaged with the aid of such a projection lens is determined by the wavelength of the
  • Projection lens can be mapped.
  • EUV extreme ultraviolet
  • both refractive optical elements and reflective optical elements are used within the microlithography projection exposure apparatus.
  • Imaging light with a wavelength in the range of 5 nm-30 nm uses exclusively reflective optical elements (EUV mirrors).
  • EUV mirrors exclusively reflective optical elements
  • Protective coating on the substrate may result in deviations from a desired surface shape, which the optical element or the reflective coating must have in order to produce the desired imaging properties.
  • One way to correct for wavefront errors from multiple optical elements that are co-located in a projection lens is to measure the wavefront errors generated by a reflective optical element and the correction to the uncoated substrate of at least one other reflective optical element
  • Surface shape of a reflective optical element for the EUV wavelength range comprising the steps of: measuring the reflective optical element and / or measuring a projection lens having the reflective optical element, with an interferometer, and irradiating the reflective optical element by the reflective Coating therethrough with the aid of electrons to produce a local compaction of the substrate of the reflective optical element in a surface area adjacent to the reflective coating and thereby to correct the surface shape of the reflective optical element.
  • a method for correcting a surface shape of a mirror has become known in which a local shape variation of a functional coating, which is arranged between a substrate and a reflective coating of the mirror, by local variation of the chemical composition of the functional Coating is produced.
  • the local variation of the chemical composition can be done by the bombardment with particles, for example by the bombardment with charged particles in the form of hydrogen ions.
  • DE 10 2005 044 716 A1 describes an optical element which has a main body (substrate) and at least one active layer which is deformable by applying at least one first field to the base body, the layer being used as a correction layer by applying the first field induced, deformation-induced, at least local and at least partial correction of at least one error of the optical
  • the layer may comprise a magnetostrictive material and the applied field may be, for example, a magnetic field.
  • a mirror arrangement has become known in which an actuator arrangement is attached to a rear side of a substrate facing away from the mirror surface, which comprises at least one active layer which is connected in area to a region of the rear side of the substrate and which comprises at least one ferroelectric material and / or a
  • piezoelectric material and / or a magnetostrictive material and / or an electrostrictive material and / or a shape memory alloy are piezoelectric materials and / or a magnetostrictive material and / or an electrostrictive material and / or a shape memory alloy.
  • an optical element comprising: a substrate, a reflective coating, at least one active layer, which has a magnetostrictive material, and at least one magnetizable layer, which is used to generate a magnetic field in the at least an active layer comprises a permanent magnetic material.
  • the layer of permanent magnetic material generates a static magnetic field which acts on the active layer and locally or possibly globally deforms it in a desired manner, i. especially in thickness, to correct the surface shape and thus wavefront errors of the optical element.
  • the static deformation of the active layer persists until the permanent magnetic layer is demagnetized by the application of a strong magnetic field.
  • the object of the invention is the method mentioned above, a reflective optical element and a projection lens with such a reflective further develop optical element such that the surface shape of the reflective optical element and the imaging properties of
  • Projection lens can be corrected with high accuracy.
  • variable Passe selectedung is made by a local shape variation is introduced in at least one introduced between the optically active coating and the substrate deformable layer having a magnetic shape memory alloy, which causes the desired correction of the surface shape.
  • Permanent deformation or shape variation of the deformable layer is understood to mean a change in shape of the deformable layer which is retained when the applied (external) electromagnetic field or magnetic field is switched off.
  • the change in the shape of the deformable layer or of the magnetic shape memory alloy is due to this Be able to align or reorient the white areas in the electromagnetic field.
  • This reorientation or alignment of the white areas remains after switching off the electromagnetic field until an electromagnetic field, pressure and / or temperature again act on the deformable layer. After switching off the external electromagnetic field or the magnetic field, no electromagnetic field or magnetic field is typically measurable outside the deformable layer.
  • the shape variation is an optically effective shape variation, i. a location-dependent variation of the shape of the layer perpendicular to the surface of the reflective optical element or perpendicular to the interface of the reflective coating of the optical element to the environment.
  • the local shape variation may be a local variation of the thickness of the deformable layer.
  • the local shape variation of the deformable layer can be generated, for example, by generating a field generating device for generating a
  • electromagnetic field in particular a magnetic field, for example in the form of an (electric) magnet
  • a magnetic field for example in the form of an (electric) magnet
  • the local magnetic flux density acting on the deformable layer at one location may be changed by changing a current flow through an electromagnet which serves to apply the magnetic field to the deformable layer in a location-dependent manner as the electromagnet moves along the deformable layer. It is not necessary that the field generating means when applying the electromagnetic field with the reflective optical element in
  • the adjustment of the local shape variation by means of the electromagnetic field or the magnetic field thus enables a contactless correction of the surface shape of a reflective optical element.
  • a correction of the surface shape or the passes can be made to the optical element, which has no influence on the roughness or reflectivity of the layers of the reflective coating or possibly other functional layers that are applied to the substrate.
  • the material of the substrate itself is not changed in the correction of the pass.
  • the material of the substrate does not matter for the passes correction, unless it is itself magnetic, which is typically the case with the materials typically used as substrates of reflective optical elements, at least for the EUV wavelength range. Since the substrate is not changed in the correction of the surface shape, a recycling of the substrate, for example, in refurbishment processes in which the coating is removed and the substrate is recoated, is possible without additional effort.
  • Shape memory alloy in the form of a ternary alloy has three constituents (typically three chemical elements), which may form, for example, an intermetallic compound, but also a non-metallic compound or alloy.
  • Ternary alloys have been found to be particularly suitable for the realization of magnetic shape memory alloys, since these have a possibly higher deformability compared to binary magnetic shape memory alloys, for example in the form of NiTi alloys.
  • the deformable layer to which the electromagnetic field is applied a magnetic
  • Shape memory alloy in the form of a particular complete Heusler alloy on. Heusler alloys are ternary
  • Deviations from the above-mentioned stoichiometry X2YZ are also possible, provided that the Heusler phase and thus the property of the
  • the constituents X and Y are typically um
  • Transition metals while Z is typically an element of the III.
  • the constituent X may be, for example, a transition metal which is selected from the group: Co, Cu, Ni, Fe and Pt.
  • the constituent Y may, for example, be Mn or another transition metal.
  • the constituent Z may be, for example, Ge, Si, Ga, Sn, Sb, Al, In, etc. If X and Z are non-magnetic elements, the magnetization is limited only to the sublattice of element Y, eg Mn. If the element X is Ni or Co, there are more
  • a magnetic shape memory alloy in the form of a NiMnGa alloy.
  • Such alloys can have a comparatively large volume change of up to 10% when a magnetic field is applied.
  • magnetostrictive materials upon application of a magnetic field, exhibit a relatively small volume change, typically less than about 0.3%.
  • Materials also the volume or length change is not maintained when the applied magnetic field is turned off.
  • the electromagnetic field in particular the magnetic field, acts for
  • Duration of exposure may be, for example, one or possibly several
  • Magnetic field strength provided - is typically sufficient to produce a permanent local shape variation in the deformable layer, which is sufficient for the correction of the surface shape.
  • saturation is typically achieved when the magnetic field is applied over a period of one or possibly several minutes.
  • the duration of action of the magnetic field on the deformable layer can vary depending on the location to the desired local
  • the magnetic field applied to the deformable layer has a magnetic flux density of less than 1.0 Tesla.
  • Typical values for the magnetic field strength or for the magnetic flux density of the applied magnetic field are in the range between approximately 0.1 Tesla and approximately 1.0 Tesla. As described above, the magnetic
  • Flux density of the magnetic field applied along the deformable layer vary depending on location to produce the desired local shape variation. It is understood that at certain locations of the deformable layer, if necessary, a field strength of less than 0.1 Telsa or no magnetic field can be applied if the desired local shape variation at this location is low or possibly undesirable.
  • an electromagnetic field in particular a magnetic field to which at least one deformable layer generates a permanent additional global shape variation of the at least one deformable layer in the form of a homogeneous thickness change.
  • a global change in thickness of the at least one deformable layer can take place, for example, by the application of an electromagnetic field, in particular a magnetic field, which acts on the at least one deformable layer before the generation of the permanent local shape variation.
  • the electromagnetic field in particular the magnetic field, acts on each location of the deformable layer in the same way, so that one over the entire surface of the deformable layer
  • a preformed deformable layer which has a greater thickness than is the case with a deformable layer to which no magnetic field was applied.
  • a preformed deformable layer has the advantage that by applying an electromagnetic field, especially a magnetic field, with suitable orientation (poling) both a permanent local shape variation in the form of an increase in the thickness of the deformable layer and a permanent local shape variation in the form of a Reduction of the thickness of the deformable layer can be made to correct the surface shape of the reflective optical element.
  • the method comprises the following steps preceding the correction of the surface shape: determining
  • Wavefront aberrations of the reflective optical element and calculating a correction surface shape of the reflective optical element from the wavefront aberrations of the reflective optical element.
  • the measurement of the wavefront aberrations or the passes of the coated reflective optical element can take place, for example, with the aid of an interferometer.
  • a correction surface shape is calculated, which is required to generate a desired surface shape of the reflective optical element.
  • the permanent local shape change of the deformable layer is chosen so that the desired correction surface shape of the reflective optical element is generated by the local shape change.
  • the magnetic flux density and / or the duration of the applied magnetic field is suitably locally, ie varies depending on the location. It may be necessary to repeatedly repeat the above steps, ie, measuring the wavefront aberrations, calculating a correction surface shape, and correcting the surface shape of the reflective optical element to achieve the target surface shape.
  • the permanent local shape variation of the at least one deformable layer is fundamentally reversible, so that the shape of the deformable layer can be replaced by the renewed application of an electromagnetic field or a
  • Magnetic field can be changed again.
  • the measurement and correction of the surface shape of the reflective optical element described above is preferably carried out before the incorporation of the reflective optical element in an optical arrangement, for example in a projection objective for a microlithography projection exposure apparatus.
  • a further aspect of the invention relates to a method for correcting the imaging properties of a projection objective for a microlithography projection exposure apparatus, comprising the following steps: determining wavefront aberrations of the projection objective, calculating a correction surface shape of at least one reflective optical element from the wavefront aberrations of the projection objective, and correcting a projection objective Surface shape of the at least one reflective optical element according to a method as described above.
  • the projection lens has the advantages already described above with respect to the surface shape correction method.
  • the wavefront aberrations of a single reflective optical element are corrected directly at the reflective optical element itself, in the method described here, the wavefront aberrations of the entire
  • Projection lens or the wavefront aberrations at least one corrected further reflective optical element of the projection lens to the above-described reflective optical element.
  • Projection lens or the wavefront aberrations at least one corrected further reflective optical element of the projection lens to the above-described reflective optical element.
  • all reflective optical elements of the projection lens may possibly have a deformable layer in order to individually correct the surface shape of each individual reflective optical element.
  • the invention also relates to an optical element, in particular for the EUV wavelength range, comprising: a substrate, a reflective coating and at least one between the substrate and the reflective
  • Coating arranged deformable layer which is a magnetic
  • Has shape memory alloy As described above, with the aid of the deformable layer, the temporary application of an electromagnetic field, for example a magnetic field, can produce a permanent local shape variation of the deformable layer, which can serve to correct the surface shape of the reflective optical element.
  • an electromagnetic field for example a magnetic field
  • a primer layer (cap layer) with typical thicknesses in the nm range to be arranged.
  • the functional coating or the functional layer may be a protective coating or "substrate protection layer” (SPL) for protecting the substrate against EUV radiation, which absorbs the EUV radiation so that it does not get to the substrate and this undesirable way can compact or the entire optical element before
  • the at least one layer comprises a magnetic shape memory alloy in the form of a ternary alloy.
  • a magnetic shape memory alloy in the form of a ternary alloy.
  • such alloys are as
  • Shape memory alloys particularly well suited.
  • the at least one layer has a magnetic shape memory alloy in the form of a Heusler alloy.
  • a magnetic shape memory alloy in the form of a Heusler alloy.
  • Volume change of typically more than about 1% and possibly up to about 10% are generated. This is favorable because a deformable layer having a comparatively small layer thickness in this case is usually sufficient to effect the correction of the surface shape.
  • the at least one deformable layer has a magnetic shape memory alloy in the form of a NiMnGa alloy.
  • a magnetic shape memory alloy in particular if these have the empirical formula Ni 2 MnGa or an optionally
  • deformable layer is possible only with an accuracy of, for example, about 0.1%, also causes the application of the deformable layer, an undesirable change in the surface shape of the reflective optsichen element that needs to be corrected.
  • a deformable layer which causes only a volume change of the order of about 0.1% to 0.2% is generally insufficient to produce both the Applying the deformable layer as well as correct by the application of the other layers deformation of the surface shape.
  • the at least one layer has a permanent local shape variation for correcting the surface shape of the optical element.
  • the layer comprising the magnetic shape memory alloy or consisting of the magnetic shape memory alloy is typically applied to the substrate as homogeneously as possible, typically by sputtering, during production, i. this has a constant thickness.
  • a local shape variation is generated in the deformable layer in the manner described above, i. the shape, in particular the thickness, of the layer varies
  • the shape of the deformable layer in particular the layer thickness of the deformable layer, over the entire surface of the reflective optical element by not more than about 1 nm (peak-to-valley, PV) varies.
  • the at least one layer has a thickness of not more than 150 nm, preferably not more than 100 nm. As described above, in a magnetic
  • Shape memory alloy for example in the form of a Heusler alloy or the use of a NiMnGa alloy by the application of a
  • a (relative) volume change of about 1% to about 10% are generated.
  • a maximum local shape variation of the layer in the form of a maximum layer thickness variation of about 1 nm can be produced.
  • Such a local shape variation is usually sufficient to prevent surface deformation of reflective optical elements caused by the application of the coating
  • Microlithography especially for EUV lithography, correct.
  • Such reflective coatings including possibly existing
  • functional layers have typical thicknesses of e.g. about 500 nm and can be applied with an accuracy of, for example, about 0.1%, so that the maximum caused by the coating error or the maximum caused by the coating deformation of the surface shape also in the order of about 1 nm lies.
  • the invention also relates to a projection objective for a microlithography projection exposure apparatus which has at least one optical element as described above.
  • all of the reflective optical elements of the projection lens may be formed as described above and include at least one layer of magnetic shape memory material for individually correcting the surface shape of each individual reflective optical element
  • the projection objective has at least one field-generating device for applying an electromagnetic field, in particular a magnetic field, to the at least one deformable layer of the at least one reflective optical element for producing a permanent local shape variation of the at least one deformable layer.
  • an electromagnetic field in particular a magnetic field
  • a magnetic field may be applied to the deformable layer as needed to produce a local shape variation of the deformable layer. This can be advantageous if during operation of the
  • the surface shape of the reflective optical element changes undesirably.
  • an electromagnetic field for example a magnetic field
  • a dynamic correction of the surface shape of the reflective optical element incorporated in the projection objective can take place.
  • the field generating device can be designed as a (conventional) electromagnet, which is optionally coupled to a movement device which makes it possible to move the field-generating device or the electromagnet along the deformable layer in order to generate the local shape variation.
  • the field generating means may comprise a plurality of (electro) magnets, for example in a grid-shaped arrangement, which may be activated individually to produce the local shape variation of the deformable layer.
  • Control of the field generating device can be provided in the projection objective or in the microlithography projection exposure apparatus in which the projection objective is arranged, a control device (or possibly a control device).
  • FIG. 1a-c show schematic representations of an EUV mirror-shaped reflective optical element which has a deformable layer with a magnetic shape memory alloy
  • FIG. 2a, b are schematic representations of a plan view and a section through a surface shape to be corrected of a reflective optical element, as well as
  • Fig. 3 is a schematic representation of a projection lens for a
  • Field generating device for applying a magnetic field to the deformable layer of a reflective optical element according to FIG. 1a-c.
  • a reflective optical element 1 for the EUV wavelength range (EUV mirror), which comprises a substrate 2 and a reflective coating 3 and which is used in a microlithography projection exposure apparatus for the EUV wavelength range (at
  • the substrate 2 is made of a material having a very low coefficient of thermal expansion (CTE), typically less than 100 ppb / K at 22 ° C or over a temperature range from about 5 ° C. to about 35 ° C.
  • CTE coefficient of thermal expansion
  • a material which has these properties is silica-doped silicate or titanium dioxide.
  • Quartz glass which typically has a silicate glass content of more than 90%.
  • silicate glass is sold by Corning Inc. under the trade name ULE® (Ultra Low Expansion glass).
  • ULE® Ultra Low Expansion glass
  • Another material group which is a very small
  • glass ceramics in which the ratio of the crystal phase to the glass phase is adjusted so that the thermal expansion coefficients of the different phases almost cancel.
  • glass ceramics are, for example, under the trade name Zerodur® from the company Schott AG or under the
  • the reflective optical element 1 is to be used in a projection exposure apparatus which is exposed to imaging light at wavelengths greater than 150 nm, e.g. at about 193 nm, materials can be used for the substrate 2, which has a higher thermal
  • the reflective coating 3 consists of a plurality of individual layers, which are formed from different materials. If the reflective optical element 1 is designed for reflection of imaging light 4 in the EUV wavelength range, the reflective coating 3 can be formed from individual layers which alternately comprise materials
  • the individual layers usually consist of molybdenum and silicon. Depending on the wavelength of the imaging light 4, other material combinations such as molybdenum and beryllium, ruthenium and beryllium or lanthanum and B 4 C are also possible.
  • such reflective coatings 3 may also include interlayers to prevent diffusion or cover layers to prevent oxidation and corrosion. On the representation of such auxiliary layers in the figures has been omitted. If the reflective optical element 1 is operated with imaging light at wavelengths of more than 150 nm, the reflective coating 3 usually also has a plurality of individual layers, which alternately
  • the reflective optical element 1 has a planar surface in the example shown in FIGS. 1a-c. This was only for better illustration of the chosen correction method according to the invention.
  • the reflective optical element 1 may have a curved surface shape.
  • concave surface shapes and convex surface shapes are possible.
  • the surface shapes can be both spherical and aspherical. After production, such a reflective optical element 1 can be measured by means of interferometric methods.
  • the reflective optical element 1 it is usually necessary for the reflective optical element 1 to already have a reflective coating 3.
  • the measurement of the surface shape 5 shows that the actual surface shape deviates from the desired surface shape (desired surface shape), which in the example shown is a plane surface shape
  • a correction of the surface shape 5 is necessary.
  • the actual surface shape 5 shown in FIG. 2 a based on the contour lines corresponds in this case to the deviation between the actual surface shape and the plane desired surface shape of the reflective optical element 1, and thus the
  • Wavefront aberrations of the reflective optical element are Wavefront aberrations of the reflective optical element.
  • deformable layer 7 is arranged.
  • the deformable layer 7 is applied directly to the substrate 2, and a protective layer 8 ("surface protection layer") is applied to the deformable layer 7, which protects the substrate 2 from the imaging light 4.
  • a protective layer 8 (“surface protection layer") is applied to the deformable layer 7, which protects the substrate 2 from the imaging light 4.
  • FIGS deformable layer 7 may alternatively be applied to the protective layer 8, so that this immediately adjacent to the refiektive
  • Coating 3 is arranged. Between the deformable layer 7 and the substrate 2, the protective layer 8 or the reflective coating 2, adhesion promoter layers (not shown) may be arranged to increase the adhesion of the deformable layer 7 to the substrate 2 or to the protective layer 8 or to the reflective coating 2 improve.
  • the deformable layer 7 has a constant or homogeneous thickness D of 100 nm over the surface of the refiective optical element 1. Both the deformable layer 7, the protective layer 8 and the reflective coating 2 by sputtering on the
  • Substrate 2 applied to ensure the greatest possible homogeneity of the respective layer thicknesses.
  • the deformable layer 7 can be used to correct the (actual) surface shape 5 of the refiective optical element 1.
  • the deformable layer 7 is a magnetic
  • a Heusler alloy namely a NiMnGa shape memory alloy having the empirical formula Ni 2 MnGa.
  • Shape memory alloy can be a permanent local by applying an electromagnetic field, such as a magnetic field 9
  • Shape variation 10 (see Figure 1 b) are generated, i. a shape variation, which is maintained when the magnetic field 9 no longer acts on the deformable layer 7.
  • the applied magnetic field 9, which penetrates the deformable layer 7, causes a local increase in the thickness D of the deformable layer 7.
  • deformable layer 7, in particular the thickness D of the deformable layer 7, are locally changed, depending on the orientation of the
  • Both an increase in the thickness D and a decrease in the thickness D of the preformed deformable layer 7 by a local positive or negative (see Fig. 1c) thickness change AD can be generated. It is understood that the global thickness change AD 'of the deformable layer 7 should not be too large so that both a local shape variation 10 in the form of a local thickness change AD with positive (see FIG. 1b) as well as with negative (see Fig. 1c) sign can be generated.
  • the strength of the change in the shape or thickness D of the deformable layer 7 depends on the duration of action of the magnetic field 9 on the deformable layer 7 and on the amount of the magnetic flux density B present at the location of the deformable layer 7 perpendicular to
  • deformable layer 7 i.e., in the Z direction of an XYZ coordinate system.
  • Thickness change AD of the deformable layer 7 unless the saturation of the change in length or the change in volume of the magnetic
  • Shape memory alloy of the deformable layer 7 is achieved.
  • a shape variation or a relative change in thickness AD / D of the deformable layer 7 of about 1% to 10% can be achieved become.
  • the thickness D of the deformable layer 7 of about 100 nm selected here it is possible for a 1%, an absolute change in thickness of approximately 1 nm is generated, which is generally sufficient for the correction of the surface shape 5 of the reflective optical element 1.
  • a magnetic flux density B of the magnetic field 9 applied to the deformable layer 7 is typically sufficient, which is less than approximately 0.1 Tesla. Under the magnetic flux density B of the applied
  • Magnetic field 9 is understood as the magnetic flux density B, which is generated by the applied magnetic field 9 at the location of the deformable layer 7.
  • Field generating device in the form of a conventional electromagnet 11 sufficient, as shown in Fig. 1 b.
  • the action of the magnetic field 9 on the deformable layer 7 is locally limited in the example shown in FIG. the magnetic field 9 acts on the deformable layer 7 only on a comparatively small surface area (in the XY plane) adjacent to the electromagnet 11.
  • the electromagnet 11 is scanned, for example, over the surface of the reflective optical element 1 and thus over the
  • Magnetic field 9 can be varied, for example by the one of a
  • Power source 12 supplied current flow I through the electromagnet 11 during the movement of the electromagnet 11 via the deformable layer. 7
  • the Duration of action of the magnetic field 9 at each location (in the X direction and in the Y direction) of the deformable layer 7 are varied by the movement of the electromagnet 11 along the deformable layer 7 is suitably controlled, so that the residence time of the electromagnet 11 at a respective Location of the deformable layer 7 varies depending on location.
  • that for generating a desired local shape variation 10 is
  • deformable layer 7 at a particular location required exposure time of the magnetic field 9 in the order of one or a few
  • the reflective coating 3 and also the protective layer 8 essentially follow in their shape the changed shape of the deformable layer 7. In other words, both the reflective coating 3 and the reflective coating 3 have their shape
  • Protective layer 8 due to the local reduction or increase in the thickness D of the deformable layer 7 no thickness variation. The result is a change in the surface shape 5 of the reflective optical element 1 in the region in which the magnetic field 9 acts on the deformable layer 7, i. a depression or an increase in the surface shape 5 is produced, although the substrate 2 remains unchanged in its shape.
  • the target surface shape is not achieved by a single correction step, so that a re-measurement of the wavefront aberrations and a renewed correction of the surface shape 5 are required. It proves to be favorable that the permanent local shape variation 10 of the deformable layer 7 is reversible, so that the shape of the deformable layer 7 can be changed by a renewed action of the magnetic field 9. Thus, a multiple measurement and a multiple correction of the surface shape 5 can be made until the desired target surface shape of the reflective optical element 1 is reached.
  • a correction of wavefront aberrations occurring in a projection objective 23 as a whole can also be performed on the reflective optical element 1.
  • FIG. 3 shows, by way of example, such a projection objective 23 in which, in addition to a further five reflective optical elements 21, a reflective optical element 1 serving as a correction element is also integrated.
  • Projection lens 23 a structure-carrying mask 29, which is arranged in an object plane 31, on an image 33 in an image plane 35
  • the projection optics 23 comprises six reflective optical elements 1, 21 with which the structure-carrying mask 29 is imaged into the image plane 35.
  • Such a projection lens 23 is usually diffraction-limited, so that the maximum possible resolution can only be achieved if the
  • Elements 1, 21 be set with high precision.
  • the projection objective 23 with all six reflective optical elements 1, 21 is interferometrically measured in order to determine the wavefront aberrations of the projection objective 23.
  • the reflective optical element 1 serving as correction element can be removed from the projection objective 23, in the manner described above by applying a magnetic field 9 to the deformable layer 7, a local shape variation 10 is generated, and in this way one for the correction of the Wavefront of the projection lens 23 are obtained suitable change of the surface shape 5 of the reflective optical element 1.
  • the reflective optical element 1 is re-installed in the projection lens 23.
  • a field-generating device 19 which is arranged at a small distance from the side of the substrate 2 of the reflective optical element 1 facing away from the incident imaging light 4, is integrated in the projection objective 23 shown in FIG.
  • the illustration of the reflective coating on the reflective optical elements 1, 21 has been omitted in the example shown in FIG. 3 for reasons of clarity.
  • the field-generating device 19 has a plurality of electromagnets 11 in a grid-like arrangement, which are arranged on a common holder 19 a, in each case to generate a magnetic field 9, which the substrate 2 of the reflective optical element 1 of penetrates its back and is applied to the deformable layer 7. It proves to be favorable that the substrate 2 of the reflective optical element 1 itself is usually non-magnetic and therefore does not or only slightly influences the magnetic field 9.
  • Each of the electromagnets 11 of the field-generating device 19 affects only a portion of the deformable layer 7, so that with the aid of
  • Field generating device 19 a local, location-dependent shape variation in the deformable layer 7 can be generated with a substantially corresponding to the distances between the electromagnets 11 spatial resolution.
  • Electromagnet 11 may possibly also a single solenoid 11 as
  • Field generating device 19 may be arranged in the projection lens 23.
  • the electromagnet 11 is typically moved by means of a moving device on the back side of the substrate 2 of the reflective optical element 1, for example in a scanning movement guided to along the entire back of the reflective optical
  • the projection objective 23 itself is integrated into an EUV lithography system 20, which in addition to the projection objective 23 has an EUV radiation source (not shown) and an illumination system (not shown) around the object plane 31, in which the mask 29 is arranged To irradiate EUV radiation.
  • EUV radiation source not shown
  • illumination system not shown
  • the above-described correction of the surface form 5 can also be applied to a reflective optical element 1 or to a projection objective for the UV wavelength range, i. at
  • such a reflective optical element 1 can also have a reflective coating 3 with a plurality of layers having different refractive indices.
  • Both the reflective optical element 1, which is designed for the EUV wavelength range, and a reflective optical element, which is designed for the UV wavelength range, may optionally have a reflective coating, which is formed only of a single layer, which increases the reflectivity of the optical element. It is understood that instead of a single deformable layer 7, the reflective optical element 1 may also comprise two or more deformable layers 7, which are arranged between the substrate 2 and the reflective coating 3.
  • a precise correction of the surface form 5 on a reflective optical element 1 can be carried out in the manner described above without negatively influencing the substrate 2, the protective layer 8 or the reflective coating 3.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Optical Elements Other Than Lenses (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)

Abstract

L'invention concerne un procédé permettant de corriger la forme de la surface d'un élément optique réfléchissant (1) présentant un substrat (2) et un revêtement réfléchissant (3). Le procédé comprend au moins l'étape suivante: correction de la forme de la surface (5) en créant une variation de forme (10) durable et locale sur au moins une couche déformable (7), qui est positionnée entre le substrat (2) et le revêtement réfléchissant (3) et qui présente un alliage à mémoire de forme magnétique. La variation de forme (10) durable et locale est réalisée par application d'un champ électromagnétique, en particulier un champ magnétique (9), sur la couche déformable (7). L'invention concerne également un élément optique réfléchissant (1) comprenant: un substrat (2), un revêtement réfléchissant (3) ainsi qu'au moins une couche déformable (7), disposée entre le substrat (2) et le revêtement réfléchissant (3), présentant un alliage à mémoire de forme magnétique.
PCT/EP2015/073153 2014-12-02 2015-10-07 Correction de surface sur des éléments optiques réfléchissants et revêtus WO2016087092A1 (fr)

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CN201580073765.0A CN107111015A (zh) 2014-12-02 2015-10-07 涂覆的反射光学元件上的表面校正
KR1020177017775A KR20170088975A (ko) 2014-12-02 2015-10-07 코팅된 반사 광학 요소에 대한 표면 보정

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DE102014224569.9 2014-12-02
DE102014224569.9A DE102014224569A1 (de) 2014-12-02 2014-12-02 Oberflächenkorrektur an beschichteten reflektiven optischen Elementen

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US10146138B2 (en) 2015-01-13 2018-12-04 Carl Zeiss Smt Gmbh Method for producing an optical element for an optical system, in particular for a microlithographic projection exposure apparatus
US11029515B2 (en) 2018-03-05 2021-06-08 Carl Zeiss Smt Gmbh Optical element, and method for correcting the wavefront effect of an optical element

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WO2020043950A1 (fr) * 2018-08-28 2020-03-05 Tikomat Oy Élément fonctionnel comprenant un alliage magnétique à mémoire de forme et son procédé de fabrication
CN115072653A (zh) * 2022-06-14 2022-09-20 北京京东方技术开发有限公司 显示面板、显示装置、三维微结构器件及其制备方法

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DE102008001005A1 (de) * 2008-04-04 2009-10-22 Forschungszentrum Karlsruhe Gmbh Verfahren zur Herstellung eines Schichtverbundes mit epitaktisch gewachsenen Schichten aus einem magnetischen Formgedächtnis-Material und Schichtverbund mit epitaktischen Schichten aus einem magnetischen Formgedächtnis-Material sowie deren Verwendung
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US10146138B2 (en) 2015-01-13 2018-12-04 Carl Zeiss Smt Gmbh Method for producing an optical element for an optical system, in particular for a microlithographic projection exposure apparatus
US11029515B2 (en) 2018-03-05 2021-06-08 Carl Zeiss Smt Gmbh Optical element, and method for correcting the wavefront effect of an optical element

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DE102014224569A1 (de) 2016-06-02
KR20170088975A (ko) 2017-08-02

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