WO2021224036A1 - Procédé de fonctionnement d'un miroir déformable et système optique comportant un miroir déformable - Google Patents

Procédé de fonctionnement d'un miroir déformable et système optique comportant un miroir déformable Download PDF

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Publication number
WO2021224036A1
WO2021224036A1 PCT/EP2021/060757 EP2021060757W WO2021224036A1 WO 2021224036 A1 WO2021224036 A1 WO 2021224036A1 EP 2021060757 W EP2021060757 W EP 2021060757W WO 2021224036 A1 WO2021224036 A1 WO 2021224036A1
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WIPO (PCT)
Prior art keywords
mirror
piezoelectric layer
temperature distribution
electrode arrangement
layer
Prior art date
Application number
PCT/EP2021/060757
Other languages
German (de)
English (en)
Inventor
Hans Michael STIEPAN
Toralf Gruner
Kerstin HILD
Evgeny SAVELYEV
Original Assignee
Carl Zeiss Smt Gmbh
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Application filed by Carl Zeiss Smt Gmbh filed Critical Carl Zeiss Smt Gmbh
Publication of WO2021224036A1 publication Critical patent/WO2021224036A1/fr

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    • 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
    • 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
    • G02B26/0825—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 flexible sheet or membrane, e.g. for varying the focus
    • 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
    • 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
    • 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
    • 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
    • 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
    • G03F7/70591—Testing optical components
    • G03F7/706—Aberration measurement
    • 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

Definitions

  • the invention relates to a method for operating a deformable mirror, and an optical system with a deformable mirror.
  • Microlithography is used to manufacture microstructured components such as integrated circuits or LCDs.
  • the microlithography process is carried out in what is known as a projection exposure system, which has an illumination device and a projection lens.
  • a substrate e.g. a silicon wafer
  • mirrors are used as optical components for the imaging process due to the lack of availability of suitable translucent refractive materials.
  • one or more mirrors in an EUV system as an adaptive mirror with an actuator layer made of a piezoelectric material
  • an electric field with locally different strengths over this piezoelectric layer by applying an electrical voltage to both sides of the piezoelectric Layer arranged electrodes is generated.
  • the reflective layer system of the adaptive mirror is also deformed so that, for example, imaging errors (possibly also temporally variable imaging errors) can be at least partially compensated for by suitable control of the electrodes.
  • the mirror 80 comprises in particular a mirror substrate 82 and a reflective layer system 91 and has a piezoelectric layer 86, which in the example is made of lead-zirconate-titanate (Pb ( Zr, Ti) 03, PZT) is made. Above or below the piezoelectric layer 86 are electrode arrangements, via which the mirror 80 can be subjected to an electric field for generating a locally variable deformation.
  • a piezoelectric layer 86 which in the example is made of lead-zirconate-titanate (Pb ( Zr, Ti) 03, PZT) is made.
  • Pb ( Zr, Ti) 03, PZT lead-zirconate-titanate
  • the second electrode arrangement facing the substrate 82 is designed as a continuous, flat electrode 84 of constant thickness, whereas the first electrode arrangement has a plurality of electrodes 90, each of which can be supplied with an electrical voltage relative to the electrode 84 via a lead 89 .
  • the electrodes 90 are embedded in a common smooth layer 88 which is made, for example, of quartz (S1O2) and serves to level the electrode arrangement formed from the electrodes 90.
  • the mirror 80 has between the mirror substrate 82 and the Mirror substrate 82 facing lower electrode 84 has an adhesive layer 83 (e.g. made of titanium, Ti) and a buffer layer 85 (e.g.
  • an actuation of the mirror 80 can be achieved.
  • the mirror 80 also has a mediator layer 87.
  • This mediator layer 87 is in direct electrical contact with the electrodes 90 (which are shown in plan view in FIG. 8a for illustration purposes only).
  • This mediator layer 87 serves to “mediate” between these electrodes 90 in the potential, whereby it has only a low electrical conductivity with the result that a voltage difference existing between adjacent electrodes 90 essentially drops across the mediator layer 87.
  • the invention relates to a method for operating a deformable mirror, the mirror having:
  • a reflective layer system for reflecting electromagnetic radiation incident on an optical effective surface of the mirror
  • At least one piezoelectric layer which is arranged between the mirror substrate and reflective layer system and has a first electrode arrangement located on the side of the piezoelectric layer facing the reflective layer system and a second electrode arrangement located on the side of the piezoelectric layer facing the mirror substrate Electrode arrangement can be acted upon by a voltage control of the first and / or the second electrode arrangement with an electric field for generating a locally variable deformation.
  • the method according to the invention has the following steps: a) determining a temperature distribution present in the region of the piezoelectric layer; and b) adapting the voltage control of the first and / or the second electrode arrangement as a function of the temperature distribution determined in step a).
  • reflective layer system is intended to include both multiple layer systems or reflective layer stacks and single layers.
  • the present invention is based in particular on the concept of adapting the voltage control of the electrode arrangements in a deformed mirror with a piezoelectric layer that can be acted upon via electrode arrangements with an electrical field to generate a locally variable deformation depending on a previously determined temperature distribution in the area of the piezoelectric layer
  • the linear expansion of the material of the piezoelectric layer which is achieved as a function of the voltage for the relevant temperature distribution - which in turn can be determined in advance by means of a calibration - is taken into account.
  • the coefficient that characterizes the voltage-dependent linear expansion of the material of the piezoelectric layer is also referred to as the d 33 coefficient and corresponds to the relevant component of the dielectric tensor responsible for the linear expansion in the direction perpendicular to the effective optical surface.
  • the invention includes, inter alia, the principle that, in the case of a mirror deformed by means of a piezoelectric layer, initially a currently im Determine the temperature distribution in the area of this piezoelectric layer and then, knowing the values of the d 33 coefficient of the piezoelectric layer that apply to the respective temperature distribution, apply the correct electrical voltage from the outset, taking into account the heating that has taken place, in order to achieve a desired deformation of the mirror .
  • the temperature distribution in the area of the piezoelectric layer can be determined in different ways. According to a preferred embodiment (but without the invention being restricted to this), the temperature distribution is determined by measuring a leakage current flowing between the electrode arrangements via the piezoelectric layer.
  • the invention is based on the consideration that the piezoelectric layer has a typically relatively high but finite electrical resistance (usually in the megaohm to gigaohm range), so that an electrical leakage current between the electrode arrangements via the piezoelectric Layer occurs, which is of a comparatively small but measurable order of magnitude (typical values of this leakage current being in the microampere range).
  • the invention now makes use of the further knowledge that said leakage current has a significant temperature dependency and can consequently be used as an indicator of the currently existing temperature in the area of the piezoelectric layer.
  • the invention also includes the concept of using the (actually parasitic) leakage current via the piezoelectric layer for temperature determination and for correct voltage control of the electrodes with regard to this temperature or the corresponding piezoelectric properties of the piezoelectric layer.
  • the temperature distribution is determined in step a) in a spatially resolved manner.
  • the temperature distribution is determined in step a) in a time-resolved manner.
  • the first or the second electrode arrangement has a plurality of electrodes, each of which can be subjected to an electrical voltage relative to the first other electrode arrangement via a supply line.
  • the voltage control in step b) is adapted in such a way that an electrical voltage is applied to these electrodes independently of one another as a function of a locally varying temperature distribution determined in step a).
  • the voltage control is adapted in step b) taking into account a calibration carried out beforehand, with this calibration determining a deformation of the piezoelectric layer for different temperatures.
  • this calibration is carried out in a calibration stand which has a heating device for setting different temperatures on the mirror, a unit for voltage control and leakage current measurement on the mirror and an interferometric measuring arrangement for measuring surface deformation of the mirror.
  • the determination of the temperature distribution in step a) comprises the measurement of a leakage current flowing between the electrode arrangements via the piezoelectric layer.
  • the measurement of the leakage current takes place in a spatially resolved manner.
  • the determination of the temperature distribution in step a) comprises an impedance measurement to determine a temperature-dependent capacitance of the piezoelectric layer.
  • the first or the second electrode arrangement has a plurality of electrodes, these electrodes being brought to the same electrical potential before the leakage current is measured.
  • one of the electrode arrangements is assigned an intermediary layer for setting an at least regionally continuous course of the electrical potential along the respective electrode arrangement.
  • the temperature distribution is determined in step a) using at least one infrared camera, in which case the temperature distribution is inferred from a camera image recorded by this infrared camera.
  • the temperature distribution is determined in step a) using an arrangement of temperature sensors located in the mirror substrate.
  • the invention further relates to an optical system with
  • the piezoelectric layer having a first electrode arrangement located on the side of the piezoelectric layer facing the reflection layer system and a second electrode arrangement on the mirror substrate facing side of the piezoelectric layer located electrode arrangement can be acted upon with an electric field for generating a locally variable deformation;
  • the optical system has a device for determining a temperature distribution present in the region of the piezoelectric layer.
  • the device for determining a temperature distribution present in the region of the piezoelectric layer is designed based on the measurement of a leakage current flowing between the electrode arrangements via the piezoelectric layer.
  • the device for determining a temperature distribution present in the region of the piezoelectric layer is designed based on an impedance measurement to determine the temperature-dependent capacitance of the piezoelectric layer.
  • the device for determining a temperature distribution present in the region of the piezoelectric layer has an infrared camera for recording a camera image of the optical active surface.
  • the device for determining a temperature distribution present in the region of the piezoelectric layer has an arrangement of temperature sensors located in the mirror substrate.
  • the mirror is designed for a working wavelength of less than 30 nm, in particular less than 15 nm.
  • the optical system is a lighting device or a projection lens of a microlithographic projection exposure system.
  • the invention further relates to a microlithographic projection exposure system with an illumination device and a projection lens, wherein the Projection exposure system has an optical system with the features described above be.
  • FIG. 1 shows a schematic illustration to explain a determination of the temperature distribution taking place in an adaptive mirror in the region of the piezoelectric layer according to an embodiment of the invention
  • FIG. 2 shows an equivalent circuit diagram for the adaptive mirror according to FIG. 1
  • FIG. 3 shows a schematic illustration to explain a determination of the temperature distribution in an adaptive mirror in the region of the piezoelectric layer according to a further embodiment of the invention
  • FIG. 4 shows a schematic representation of a calibration stand which can be used in the method according to the invention
  • FIG. 5 shows a diagram for explaining a possible sequence of a method according to the invention
  • FIG. 6 shows a schematic illustration to explain the possible structure of a microlithographic projection exposure system designed for operation in the EUV;
  • FIG. 7 shows a schematic illustration to explain the possible structure of a microlithographic projection exposure system designed for operation in the VUV.
  • FIG. 8 shows a schematic illustration to explain the possible structure of a conventional adaptive mirror.
  • Fig. 1 shows a schematic illustration to explain the structure of a mirror according to the invention in an exemplary embodiment of the inven tion.
  • the mirror 10 comprises a mirror substrate 12 which is produced from any suitable mirror substrate material.
  • Suitable mirror substrate materials include titanium dioxide (Ti0 2) -doped quartz glass, which in way of example only (and without the invention being limited thereto) under the trade designation ULE ® (manufactured by Corning Inc.) sold material can be used.
  • Other suitable materials are Lithiumaluminosili- cate glass ceramics, for example, under the names Zerodur ® (Schott AG) or Clearceram ® (manufactured by Ohara Inc.) sold.
  • other materials such as silicon (Si) are also conceivable.
  • the mirror 10 has, in a manner known per se, a reflective layer system 21 which, in the embodiment shown, comprises a molybdenum-silicon (Mo-Si) layer stack merely by way of example.
  • a suitable one can be used merely by way of example Structure comprise about 50 layers or layer packages of a layer system of molybdenum (Mo) layers with a layer thickness of 2.4 nm each and silicon (Si) layers with a layer thickness of 3.3 nm each.
  • the reflective layer system can also be a single layer.
  • the mirror 10 can in particular be an EUV mirror of an optical system, in particular of the projection objective or the lighting device of a microlithographic projection exposure system.
  • the mirror 10 has a piezoelectric layer 16, which in the example is made of lead zirconate titanate (Pb (Zr, Ti) 03, PZT). Above or below the piezoelectric layer 16 are electrode arrangements, via which the mirror 10 can be subjected to an electric field for generating a locally variable deformation.
  • the second electrode arrangement facing the substrate 12 is designed as a continuous, flat electrode 14 of constant thickness, whereas the first electrode arrangement has a plurality of electrodes 20, each with an electrical voltage relative to the electrode 14 via a lead 19 can be acted upon.
  • the electrodes 20 are embedded in a common smooth layer 18, which is made of quartz (S1O2), for example, and is used to level the electrode arrangement formed by the electrodes 20.
  • the mirror 10 has an adhesive layer 33 (e.g. made of titanium, Ti) between the mirror substrate 12 and the lower electrode facing the mirror substrate 12 and a buffer layer 15 (e.g. made of LaNiOs) arranged between the electrode arrangement facing the substrate 12 and the piezoelectric layer 16 ), which further supports the growth of PZT in an optimal, crystalline structure and ensures constant polarization properties of the piezoelectric layer over the service life.
  • an adhesive layer 33 e.g. made of titanium, Ti
  • a buffer layer 15 e.g. made of LaNiOs
  • the application of an electrical voltage leads to the Electrodes 20 via the developing electric field to deflect the piezoelectric layer 16.
  • an actuation of the mirror 10 can be achieved - e.g. to compensate for optical aberrations, e.g. .
  • the mirror 10 also has a mediator layer 17.
  • This mediator layer 17 is in direct electrical contact with the electrodes 20 (which are shown in Fig. 1 only for illustration in plan view) and serves to "mediate" between the electrodes 20 in potential, whereby they have only a low electrical conductivity (preferably less than 200 Siemens / meter (S / m)), so that a voltage difference existing between adjacent electrodes 20 essentially drops over the mediating layer 17.
  • this temperature determination takes place by measuring the leakage current flowing between the electrode arrangements across the piezoelectric layer, the invention showing a significant temperature dependence of this leakage current or the temperature dependence of the ohm, which is decisive for the magnitude of the leakage current .
  • Fig. 2 shows for explanation of this concept, an equivalent circuit diagram for the purpose described with reference to FIG. 1, structure of the deformable mirror 10. In this case, whoever the to the individual electrodes 20 of the reflection layer system 21 facing the electrode assembly, respectively voltages Ui, U 2, ..., U n created.
  • the mediator layer 17 present in the mirror 10 as described can be viewed as a continuous voltage divider from a plurality of ohms ' resistors RML as shown in FIG.
  • the electrode arrangement facing the substrate 12 is grounded according to FIG. 2, and the application of voltage to the electrodes 20 to achieve expansion of the piezoelectric layer 16 or an accompanying mirror deformation corresponds to the charging of the electrodes 20 of the first electrode arrangement, the electrode 14 of the second the electrode assembly as well as the intervening piezoelectric layer 16 formed capacitors C.
  • the piezoelectric layer 16 is according to Fig. 2, see also as a voltage divider from Ohm 'resistors RPZT viewed.
  • a corresponding measuring device for measuring the leakage current is only indicated in FIG. 1 and denoted by “25”.
  • Such a measuring device 25 can in particular per electrode 20 or Lead 19 have an ammeter, wherein the corresponding ammeter can also be housed away from the mirror 10, for example in an electronic module typically for the control of the electrodes 20 that is already present in the electronics module.
  • measuring electrodes that are not in electrical contact with the mediation layer 17 or that are electrically insulated from this mediation layer 17 can also be provided for measuring the leakage current. Since no optically effective mirror deformation is achieved in the area of such measuring electrodes, the relative surface area of said measuring electrodes is preferably selected to be small (in particular less than 1%, further in particular less than 0.1%).
  • a leakage current-based determination of the temperature distribution in the region of the piezoelectric layer 16 can also take place using the fact that the capacitance of the piezoelectric layer 16 also has a significant temperature dependency.
  • an alternating electric field can be used temporarily via the electrode arrangements and for the purpose of determining the temperature according to the invention applied and an impedance measurement carried out.
  • This alternating electric field can in particular have a frequency in the range from 10 Hz to 100 kHz, further in particular in the range from 100 Hz to 10 kHz.
  • the concept according to the invention is not limited to the measurement of leakage currents described above.
  • the temperature distribution in the area of the piezoelectric layer can also be determined using temperature sensors which - as only indicated schematically in FIG. 3 - can be arranged, for example, within the mirror substrate and as close as possible to the piezoelectric layer .
  • FIG. 3 components that are analogous or essentially functionally the same as in FIG. 1 are denoted by reference numbers increased by “20”.
  • the temperature sensors 45 can be equipped in particular in the form of temperature-dependent resistors or impedances coupling to the temperature field of the piezoelectric layer 36, bridge circuits known in the prior art can be used for high-precision resistance measurement.
  • the determination according to the invention of the temperature distribution present in the region of the piezoelectric layer can also be carried out using an infrared camera, in which case the temperature distribution can be inferred from a camera image recorded by this infrared camera.
  • the voltage control of the first and / or second electrode arrangement is adapted as a function of this temperature distribution, so that the mirror deformation achieved via this voltage control or that in the optical system is ultimately If the aberration correction is effected, the corresponding current temperature distribution and the resulting piezoelectric properties (in particular the value of the d33 coefficient) are taken into account.
  • the deformation of the piezoelectric layer for different temperatures is preferably determined in a preliminary calibration.
  • a calibration stand that can be used for this purpose can, for example, have an interferometric structure in which the deformation of the piezoelectric layer is determined at a given electrical voltage and at different temperatures (e.g. set via an infrared heating source).
  • Fig. 4 shows a schematic representation of the possible structure of such a calibration stand.
  • the expansion coefficient d33 is determined via the interferometric measurement of the surface deformation of the deformable mirror (labeled “54” in FIG. 4).
  • a heating device 55 eg an IR radiator
  • the calibration stand also has an infrared camera 57 for temperature measurement and an electronic unit labeled “56” for voltage control and leakage current measurement.
  • a light source not shown
  • CGH Computergenerier th hologram
  • a Reference wave By reflection of this CGH 53 emanating the electromagnetic radiation at a reference mirror 60 is a Reference wave is generated, whereas a test wave is generated by reflection of the electromagnetic radiation emanating from the CGH 53 on the mirror 54.
  • the reference wave and the test wave reach a detector 59 (eg in the form of a CCD camera) via the beam splitter 52 and an ocular lens 58 and interfere there with one another, so that an interferogram for the Mirror surface of the mirror 54 is drawn on.
  • Fig. 5 shows a diagram to explain the possible sequence of a method according to the invention. 5 initially in an optional step S51 using a calibration stand (e.g. with the structure described above with reference to FIG. 4) for different temperatures and different electrical voltages applied to the electrode arrangements of the deformierba ren mirror, the electrode-resolved ( or spatially resolved) determination of the d33 coefficient or the deformation of the piezoelectric layer of the deformable mirror as a function of the leakage current.
  • a calibration stand e.g. with the structure described above with reference to FIG. 4
  • a subsequent step S52 the values of the d33 coefficient obtained for the respective electrodes of the deformable mirror are stored in a database (created for the individual mirror) as a function of the leakage current. Then, in step S53, a target profile of the relevant deformable mirror is specified when the microlithographic projection exposure system is in operation.
  • step S54 the measurement of the respective leakage currents is carried out, whereupon in step S55 a location-dependent determination of the d33 coefficient takes place on the basis of the measured leakage currents and the aforementioned database.
  • an electrical voltage required to set the desired target profile is determined. This electrical voltage is in step S57 to the Electrode arrangements of the deformable mirror applied.
  • a periodic control measurement of the leakage currents is carried out.
  • FIG. 6 shows a schematic illustration of an exemplary projection exposure system designed for operation in the EUV, in which the present invention can be implemented.
  • an illumination device in a projection exposure system 600 designed for EUV has a field facet mirror 603 and a pupil facet mirror 604.
  • the light from a light source unit which comprises 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 after the pupil facet mirror 604.
  • a deflecting mirror 607 is arranged in the light path below, which deflects the radiation hitting it onto an object field in the object plane of a projection objective comprising six mirrors 651-656.
  • a reflective structure-bearing mask 621 is arranged on a mask table 620, which is imaged with the aid of the projection lens in an image plane in which a substrate 661 coated with a light-sensitive layer (photoresist) is located on a wafer table 660.
  • the projection exposure system 700 has an illumination device 710 and a projection objective 720.
  • the lighting device 710 is used to illuminate a structure-bearing mask (reticle) 730 with light from a light source unit 701, which comprises, for example, an ArF excimer laser for a working wavelength of 193 nm and beam shaping optics that generate a parallel light bundle.
  • the lighting device 710 has an optical unit 711 which, among other things, includes a deflecting mirror 712 in the example shown.
  • the optical unit 711 can, for example, be a diffractive optical unit for generating different lighting settings (ie intensity distributions in a pupil plane of the lighting device 710) Element (DOE) and have a zoom axicon system.
  • a light mixing device (not shown) in the beam path, which, for example, in a manner known per se, can have an arrangement of micro-optical elements suitable for achieving light mixing, as well as a lens group 713, behind which there is a field plane with a reticle masking system (REMA), which is imaged by a REMA lens 714 following in the direction of light propagation onto the structure-bearing mask (reticle) 730 arranged in a further field plane and thereby delimits the illuminated area on the reticle.
  • reticle masking system reticle masking system
  • the structure-bearing mask 730 is imaged with the projection objective 720 on a substrate or a wafer 740 provided with a light-sensitive layer (photoresist).
  • the projection objective 720 can in particular be designed for immersion operation, in which case an immersion medium is located in front of the wafer or its light-sensitive layer in relation to the direction of light propagation. Furthermore, it can, for example, have a numerical aperture NA greater than 0.85, in particular greater than 1.1.
  • any mirror of the projection exposure apparatus 600 or 700 described with reference to FIG. 6 or FIG. 7 can be configured as a deformable or adaptive mirror in the manner according to the invention.

Abstract

L'invention concerne un procédé de fonctionnement d'un miroir déformable et un système optique comportant un miroir déformable, le miroir (10, 30) comprenant un substrat de miroir (12, 32), un système de couche de réflexion (21, 41) servant à réfléchir un rayonnement électromagnétique qui est incident sur une zone optique active (11, 31) du miroir, et au moins une couche piézoélectrique (16, 36) qui est disposée entre le substrat de miroir et le système de couche de réflexion et qui peut être soumise à un champ électrique au moyen d'un premier agencement d'électrodes disposé sur le côté de la couche piézoélectrique qui fait face au système de couche de réflexion et d'un second agencement d'électrodes disposé sur le côté de la couche piézoélectrique qui fait face au substrat de miroir par l'actionnement de la tension du premier et/ou du second agencement d'électrodes afin de générer une déformation localement variable. Un procédé selon la présente invention comporte les étapes suivantes : déterminer une distribution de température présente dans la région de la couche piézoélectrique ; et ajuster l'actionnement de la tension du premier et/ou du second agencement d'électrodes en fonction de la distribution de température déterminée à l'étape a).
PCT/EP2021/060757 2020-05-07 2021-04-23 Procédé de fonctionnement d'un miroir déformable et système optique comportant un miroir déformable WO2021224036A1 (fr)

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DE102020205752.4A DE102020205752A1 (de) 2020-05-07 2020-05-07 Verfahren zum Betreiben eines deformierbaren Spiegels, sowie optisches System mit einem deformierbaren Spiegel

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DE102022200206A1 (de) 2022-01-11 2023-07-13 Carl Zeiss Smt Gmbh Spiegel, insbesondere für eine mikrolithographische Projektionsbelichtungsanlage
DE102022210245A1 (de) 2022-09-28 2024-03-28 Carl Zeiss Smt Gmbh Spiegelvorrichtung, insbesondere für eine mikro-lithographische Projektionsbelichtungsanlage, und Verfahren zum Messen der Temperatur eines Spiegels
DE102022210244A1 (de) 2022-09-28 2024-03-28 Carl Zeiss Smt Gmbh Spiegelvorrichtung, insbesondere für eine mikrolithographische Projektionsbelichtungsanlage, und Verfahren zum Messen der Temperatur eines Spiegels

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