WO2008122410A2 - Elément de correction optique, procédé de correction des aberrations d'images dues à la température dans les systèmes optiques, objectif de projection et appareil d'exposition par projection pour la lithographie de semi-conducteurs - Google Patents

Elément de correction optique, procédé de correction des aberrations d'images dues à la température dans les systèmes optiques, objectif de projection et appareil d'exposition par projection pour la lithographie de semi-conducteurs Download PDF

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Publication number
WO2008122410A2
WO2008122410A2 PCT/EP2008/002693 EP2008002693W WO2008122410A2 WO 2008122410 A2 WO2008122410 A2 WO 2008122410A2 EP 2008002693 W EP2008002693 W EP 2008002693W WO 2008122410 A2 WO2008122410 A2 WO 2008122410A2
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Prior art keywords
liquid layer
exposure apparatus
correction element
optical
projection exposure
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PCT/EP2008/002693
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English (en)
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WO2008122410A3 (fr
Inventor
Daniel Kraehmer
Olaf Conradi
Aurelian Dodoc
Ulrich Loering
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Carl Zeiss Smt Ag
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Application filed by Carl Zeiss Smt Ag filed Critical Carl Zeiss Smt Ag
Publication of WO2008122410A2 publication Critical patent/WO2008122410A2/fr
Publication of WO2008122410A3 publication Critical patent/WO2008122410A3/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
    • G03F7/7095—Materials, e.g. materials for housing, stage or other support having particular properties, e.g. weight, strength, conductivity, thermal expansion coefficient
    • G03F7/70958—Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/08—Catadioptric systems
    • G02B17/0892—Catadioptric systems specially adapted for the UV
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/008—Mountings, adjusting means, or light-tight connections, for optical elements 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
    • G03F7/70216—Mask projection systems
    • G03F7/70225—Optical aspects of catadioptric systems, i.e. comprising reflective and refractive 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

Definitions

  • the invention relates to an optical correction element for an optical system, to a method for the correction of temperature-induced imaging aberrations in optical systems, and to a projection exposure apparatus for semiconductor lithography in which the optical correction element and the method are used.
  • Figure 1 illustrates a projection exposure apparatus 1 for semiconductor lithography according to the prior art.
  • This apparatus serves for the exposure of structures onto a substrate coated with photosensitive materials, which substrate is generally predominantly composed of silicon and is referred to as wafer 2, for the production of semiconductor components, such as e.g. computer chips.
  • the projection exposure apparatus 1 essentially comprises an illumination device 3, a device 4 for receiving and exactly positioning a mask provided with a structure, a so-called reticle 5, which is used to determine the later structures on the wafer 2, a device 6 for the mounting, movement and exact positioning of precisely said wafer 2, and an imaging device, namely a projection objective 7, with a plurality of optical elements 8 which are mounted by means of mounts 9 in an objective housing 10 of the projection objective 7.
  • the basic functional principle provides for imaging the structures introduced into the reticle 5 onto the wafer 2; the imaging is generally implemented in demagnifying fashion. After exposure has been effected, the wafer 2 is moved further in the arrow direction, such that a multiplicity of individual fields, each having the structure prescribed by the reticle 5, are exposed on the same wafer 2. On account of the step-by-step advancing movement of the wafer 2 in the projection exposure apparatus 1, the latter is often also referred to as a stepper.
  • the illumination device 3 provides a projection beam 11 required for the imaging of the reticle 5 on the wafer 2, for example light or a similar electromagnetic radiation.
  • a laser or the like can be used as a source for this radiation.
  • the radiation is shaped in the illumination device 3 by means of optical elements in such a way that the projection beam 11, upon impinging on the reticle 5, has the desired properties with regard to diameter, polarization, shape of the wavefront and the like.
  • the projection objective 7 has a multiplicity of individual refractive, diffractive and/or reflective optical elements such as e.g. lenses, mirrors, prisms, terminating plates and the like.
  • the optical elements 8 which are formed e.g. as lenses and are arranged in the projection exposure apparatus heat up during the lithography process, such that image aberrations occur which can make it more difficult or even impossible to effect imaging of the desired structures.
  • the heating of the lenses is caused by the absorption of the useful radiation having a specific wavelength, used for the exposure, within the lens material and the layer materials, e.g. within antireflection layers.
  • a correction by means of manipulators such as e.g. manipulator lenses is usually performed.
  • Said lenses can be for example displaced, tilted or else deformed.
  • Wavefront aberrations which can be described by functions with higher radial and azimuthal polynomials are generally difficult to correct.
  • the mechanical deformations can generally only be established for lower orders, such that a comprehensive correction of the wavefront is impossible.
  • Wavefront aberration here denotes the phase deviation from an ideal spherical wave, which in the ideal case converges at the desired image point.
  • the object of the present invention is to specify a method and devices by means of which thermally induced imaging aberrations in optical systems, in particular in projection objectives for semiconductor lithography, can be corrected rapidly, simply and efficiently.
  • optical useful radiation is understood to mean that optical radiation which passes through the optical elements associated with the optical system when the optical system is used as intended.
  • the optical useful radiation of a projection objective in semiconductor lithography is the ultraviolet radiation used for imaging the structures of the reticle onto the wafer.
  • the optical useful radiation itself is used for the correction, a self-compensation in particular of the temperature-induced imaging aberrations of the optical system can be achieved in a simple and efficient manner.
  • the intensity distribution of the optical useful radiation used in the liquid layer corresponds to the intensity distribution in most of the rest of the optical elements of the system and that the temperature distribution generated by the absorption in the liquid layer thus substantially corresponds to the intensity distribution of the optical useful radiation, the assumption can be made that precisely in the regions in which the temperature-induced imaging aberrations are maximal, the correction effect of the liquid layer is also maximal.
  • the correction effect of the liquid layer is essentially based on the fact that on account of the temperature change in the liquid layer, the refractive index also changes locally. This change in the refractive index results in a local change in the course of the wavefront of the incident optical radiation, which precisely compensates for the induced deviations from the ideal wavefront given a suitable choice of the properties of the liquid layer.
  • the liquid layer can be laterally extended substantially perpendicular to the optical axis of the system and be formed in particular as a liquid plane-parallel plate.
  • the liquid layer can be formed as a liquid lens having at least one curved surface.
  • the thickness of the plane-parallel plate or the geometrical parameters of the liquid lens can be kept constant during the operation of the optical system since the compensation of the imaging aberrations is not achieved by means of a change in the geometry, but rather, as already described above, by means of a change in the distribution of the refractive index in the liquid.
  • two plane-parallel plates used as delimiting elements are arranged in a manner fixed with respect to one another.
  • Water in particular, has proved worthwhile as a liquid for forming the liquid layer according to the invention.
  • Water has a large negative temperature coefficient of the refractive index dn/dT in the region of -100*10 ⁇ 6 /K at a wavelength of 193 nm. This value has a magnitude approximately five times as large as in the case of quartz, but exhibits an opposite sign.
  • the aforementioned differences in the material constants can thus advantageously be utilized for the compensation of the imaging aberrations in an optical system. Since the absorption of electromagnetic radiation having the aforementioned wavelength within the water is more than one order of magnitude greater than in the case of quartz, a local heating within the water will also be rapidly established.
  • liquids are also appropriate as an alternative to the use of water; thus, e.g. interesting candidates are the so-called high-index liquids. Examples that may be mentioned include cyclohexane having a 193-nm refractive index of 1.57 (close to the refractive index of quartz glass) , or decalin having a refractive index of approximately 1.65.
  • the optical properties of the liquid layer can be set within a certain range. In this way it is possible to compensate for fluctuations of the absorption in optical elements such as e.g. lenses or layers which can adversely influence the effectiveness of a self- compensating liquid layer.
  • One advantageous possibility for such setting consists in altering the absorption properties of the liquid layer by adding e.g. salts such as e.g. sodium chloride, calcium chloride or potassium iodide, all of which have a very good solubility in water.
  • the absorption will rise with the concentration of the salts, such that it is advantageous always to begin with a certain starting concentration and, during a calibration step for the system, to alter the absorption of the liquid layer until the self-compensation is set optimally.
  • the liquid layer formed as a liquid plane-parallel plate can be arranged in particular between two substantially plane-parallel plates which contain quartz glass or CaF 2 or comprise the materials mentioned.
  • the two substances mentioned are established and well-controlled materials which are widely used in optical systems and the properties of which are well known .
  • the ratio of the thickness of the liquid layer to the summed thickness of the two substantially plane-parallel plates lies between 0.2 and 1.0, preferably between 0.25 and 0.75, particularly preferably between 0.3 and 0.5.
  • the plane-parallel plates contain CaF 2 it is advantageous if the ratio of the thickness of the liquid layer to the summed thickness of the two substantially plane-parallel plates lies between 0.1 and 2.0, preferably between 0.3 and 1.5, particularly preferably between 0.5 and 1.
  • the summed thickness of the two substantially plane-parallel plates can lie in particular within a range of between 1.5 mm and 15 mm, preferably between 2 mm and 12 mm.
  • the optical correction element In order to improve or ensure the functionality of the optical correction element according to the invention, it may be advantageous to reduce or prevent the convection of the liquid within the liquid layer.
  • the convection would have the effect of levelling out the temperature differences along the lateral extent of the liquid layer, whereby the correction effect would be reduced.
  • additional elements can be arranged in the liquid layer.
  • the aforementioned additional elements create in particular honeycomb-shaped or rectangular partial spaces which are closed off relative to one another and which subdivide the liquid layer.
  • the refractive index of the liquid is adapted to the refractive index of the surrounding material in the cold state.
  • additional temperature-regulating elements are present for modifying the temperature distribution in the liquid layer.
  • the liquid layer can be heated in a targeted and spatially local fashion for the purpose of fine adaptation and for the purpose of enhancement of flexibility. This can be done in a manner adapted to the respective conditions of use during the operation of the optical correction element.
  • An alternative possibility with regard to heating is to utilize infrared irradiation.
  • infrared irradiation it should be taken into consideration that e.g. water is sufficiently transparent only in a relatively narrow spectral range for optical applications and is very highly absorbent in the spectral range above approximately 2 ⁇ m.
  • the surrounding material should not be too highly absorbent at the wavelength under consideration.
  • the IR radiation can be coupled in by means of a plurality of optical systems fitted laterally with respect to the correction element.
  • direct coupling in using optical waveguides such as e.g. fibres is conceivable.
  • An advantageous choice for the location of the correction element according to the invention in the projection exposure apparatus in this case consists in arranging the optical correction element at a distance from a pupil plane which corresponds to a subaperture ratio of greater than 0.7.
  • the subaperture ratio is divided by
  • R is the marginal ray height and H is the principal ray height, and these ray heights are measured in a given plane which is parallel to a pupil plane of the optical system.
  • the subaperture ratio assumes values of between 0 and 1.
  • the subaperture ratio has the value 1 in each pupil plane of the optical system and the value 0 in each field plane of the optical system.
  • This definition is applied in particular for projection optics for semiconductor lithography since these are corrected for a maximum object height and maximum aperture, depending on the projection optic. As a result, a maximum object height and an aperture are naturally assigned to such projection optics as optical systems.
  • the greatest contributions to the aberrations of a projection exposure apparatus originate from so-called pupil aberrations, which can be corrected the most effectively in the region of the pupil.
  • the region of the pupil plane is a particularly favourable location for performing an image aberration correction by means of optical correction elements since, through measures in the pupil plane, it is possible to achieve identical types of modifications of the imaging in each location of an image plane.
  • a further correction element according to the invention can be arranged near the field or intermediately between field and pupil, for example, in order to realize an additional correction effect.
  • the correction potential of the method described and of the optical element according to the invention is manifested particularly in projection exposure apparatuses having illumination devices suitable for generating a dipole illumination.
  • the assumption can be made of a particularly inhomogeneous distribution of the absorbed optical power in the optical elements of the projection exposure apparatus.
  • the aforementioned correction potential can be increased even further by virtue of the optical useful radiation radiating through the correction element according to the invention a number of times, in particular twice.
  • Figure 1 shows a projection objective for semiconductor lithography according to the prior art (cf. introduction to the description) ;
  • Figure 2 shows an exemplary optical correction element
  • FIG. 3 shows a clear illustration of the principle underlying the invention
  • Figure 4 shows an illustration of the corrected wavefront (field centre) in figure parts 4a) and 4b) ;
  • Figure 5 shows a first exemplary embodiment of a projection objective in which two correction elements according to the invention are arranged
  • Figure 6 shows an alternative design of a projection objective in which two correction elements according to the invention are likewise used
  • Figure 7 shows a further example of a projection objective in which the correction elements according to the invention are applied.
  • Figure 8 shows the correction potential of different arrangements of the correction elements in figure parts 8a) and 8b) ;
  • Figure 9 shows an illustration of the required thicknesses of the liquid layer as a function of the thickness of the delimiting elements
  • Figure 10 shows two possible variants for the configuration of the correction element in a plan view
  • Figure 11 shows a projection exposure apparatus in which a correction element according to the invention is arranged in the projection objective
  • Figure 12 shows a further variant of the invention, in which the delimiting elements exhibit non- plane surfaces
  • Figure 13 shows an optical correction element according to the invention with temperature-regulating elements
  • Figure 14 shows an additional variant for suppressing convection
  • Figure 15 shows a further possibility for suppressing convection
  • Figure 16 shows a further variant of the invention in which convection is avoided.
  • Figure 2 shows an exemplary optical correction element 21, having the two delimiting elements 22 and 23 formed as plane-parallel plates.
  • liquids other than water e.g. a high-index liquid such as e.g. cyclohexane or decalin, are also conceivable for the liquid layer 24.
  • the delimiting elements 22 and 23 can comprise quartz glass or CaF 2 or else some other material.
  • the latter can contain in particular salts such as e.g. sodium chloride, calcium chloride or potassium iodide.
  • Figure 3 clearly illustrates the principle underlying the invention.
  • Figure 3 shows the disturbed wavefront of an inhomogeneously heated lens element 25 near the pupil.
  • the inhomogeneous heating of the lens element 25 may be attributable to a dipole illumination.
  • the right-hand figure part b) illustrates the disturbed wavefront of the optical correction element 21 according to the invention having the liquid layer 24 and the delimiting elements 22 and 23.
  • Figure 3 clearly reveals that the disturbance of the wavefronts is virtually identical apart from the respective sign. Consequently, a correction effect can be obtained through a suitable choice of the thickness of the liquid layer 24.
  • Figure 4 shows an illustration of the corrected wavefront (field centre) in figure parts 4a) and 4b) .
  • subfigure 4a) shows the wavefronts after a correction by means of exclusively active manipulators according to the prior art
  • Figure 4b illustrates the wavefront after compensation by means of the correction element according to the invention. The considerably better correction of the wavefront by the correction element according to the invention can clearly be discerned.
  • Figure 5 shows a first exemplary embodiment of a catadioptric projection objective 7 having two folding mirrors, in which two correction elements 21 according to the invention are arranged.
  • the correction elements 21 each comprise two plane plates not designated in any greater detail in the figure, the spacing between the plane plates being filled with water.
  • the compensation of the wavefront altered by heating of the surrounding optical elements, not designated in any greater detail in Figure 5, is achieved in this way. It goes without saying that the correction elements 21 according to the invention can be arranged at any desired positions within the projection objective 7.
  • P is the sagitta of the relevant surface parallel to the optical axis
  • h is the radial distance from the optical axis
  • r is the radius of curvature of the relevant surface
  • K is the conic constant
  • Cl, C2, ... are the aspheric constants presented in the table.
  • Figure 6 shows an alternative design of a projection 7 in which three correction elements 21 according to the invention are used.
  • the design of the projection objective 7 as illustrated in Figure 6 is distinguished by the fact that the beam path is led in such a way that the optical useful radiation radiates twice through the correction element 21' situated in the vertical branch of the beam path.
  • the projection beam in the course of passing through the projection objective 7, the projection beam is deflected by 90° from the original direction via the reflective elements 31, 32.
  • the projection beam exhibits a T-shaped course when passing through the projection objective 7.
  • courses that deviate more or less from the T-shape are also conceivable.
  • For the deflection of the projection beam it is also possible to use optical elements whose deflecting effect is not based on reflection but rather for example on diffraction effects or other optical effects.
  • Figure 7 shows a further example of a projection objective 7 in which the correction elements 21 according to the invention are applied.
  • the correction element 21 is situated in the region of a pupil plane of the projection objective 7, said pupil plane not being designated in the drawing.
  • an optical correction element it is possible for an optical correction element to be arranged not (only) in the region of the upper pupil plane, that is to say in the region of that pupil which is situated in the vicinity of the reticle, but rather in the region of a lower or the bottommost pupil plane, that is to say in the vicinity of the wafer.
  • the region directly upstream or downstream of one of the three biconvex lenses 26 is appropriate for this.
  • the advantage of choosing this location in the projection objective for the optical correction element 21 according to the invention is that the beam divergence is smaller in the region of the lower pupil plane than in the region of the upper pupil plane. That is to say that the angular scattering of the individual beam bundles of the projection light is smaller in the region of the lower pupil plane than in the region of the upper pupil plane.
  • This is accompanied by a smaller variance of the optical path of the projection beam bundles through the optical correction element 21 according to the invention and, consequently, an improved manipulator effect or compensation effect.
  • the associated convection problems can be effectively reduced in particular with the measures described below in particular with reference to Figures 13 and 14.
  • Figure 8 shows, in figure part 8a) , the correction potential of the arrangement shown in Figure 7;
  • Figure 8b) illustrates the correction potential of an arrangement in which one correction element 21 is arranged in the vicinity of a pupil plane and another correction element is arranged in the vicinity of a field plane of the projection objective.
  • the correction elements 21 in both cases each comprise two 5 mm thick SiO 2 plates with a layer of water with a thickness of 4 mm arranged between the plates.
  • the relation of the thicknesses of the liquid layer and of the delimiting elements for an optimum compensation effect of the correction element according to the invention will be considered by way of example below.
  • the fundamental stipulation here is that the temperature coefficient of the refractive index (dn/dT) of the liquid used exhibits a different sign from that of the surrounding material, in particular of the material of the optical elements used in the projection objective.
  • the relation between the thickness of the liquid layer and the summed thickness of the delimiting elements follows the following formula:
  • the quantity D wate r/Dgiass is the relation between liquid thickness and thickness of the surrounding glass material. Furthermore, dn g i ass /dT and dn water /dT designate the temperature coefficients of the refractive index of the glass material and, respectively, of the liquid used.
  • the quantity Di* ⁇ Ti is equal to the product of individual lens thickness and temperature rise within the lens element i. The sum over all i (with the exception of the correction element itself) identifies the contributions of all the lens elements to the overall effect.
  • the temperature within the liquid is approximately equal to the temperature of the delimiting glass surfaces.
  • the temperature of the liquid decreases as the thermal conductivity increases (e.g. quartz -> CaF 2 ) .
  • the required thickness of the liquid layer increases as the thermal conductivity increases .
  • a layer of water with two delimiting glass plates can be represented approximately as a homogeneous element having effective absorption a eff and thermal conductivity ⁇ efff where the following hold true:
  • Figure 9 illustrates the required thicknesses of the layer of water as a function of a thickness of the delimiting elements.
  • the glass types quartz and CaF 2 are assumed for the material of the delimiting elements.
  • the curve parameter in Figure 9 is the wavefront aberration to be compensated for in the overall objective (200 nm and 150 nm) . This can be calculated by means of the temperature change and the thicknesses of the optical elements, in particular of the lenses in the projection objective.
  • the projection objective can be modelled as an effective average lens.
  • This effective lens can be determined by the optical path lengths on the optical axis and along a marginal ray. From the point of view of the heating effect, the overall objective behaves equivalently to a lens having positive refractive power.
  • a liquid lens having a larger centre thickness than edge thickness should be used. This lens results from equivalent considerations to the above representation.
  • Figure 12 illustrates some exemplary embodiments of an optical correction element 21 having delimiting elements 22 and 23 having non-plane surfaces .
  • the liquid layer is structured e.g. in honeycomb-shaped fashion substantially orthogonally with respect to the direction of the optical useful radiation, that is to say that one of the delimiting elements is structured in such a way that the liquid is "filled" into individual cells and closed off as it were by the second delimiting element.
  • the heat exchange via convection is greatly suppressed in this way. It is furthermore advantageous to adapt the refractive index of the liquid to the refractive index of the surrounding material of the delimiting elements. This ensures that the honeycomb structure, in the cold state, has an optically homogeneous appearance and does not cause any disturbing optical path differences .
  • Figure 10 shows two possible variants for the configuration of the correction element in a plan view.
  • additional elements 33 are provided which subdivide the liquid layer (not designated in Figure 10) into individual partial spaces 34.
  • the partial spaces 34 are formed in honeycomb-shaped fashion in the variant illustrated in Figure 10a) , whereas they are configured as rectangles, in particular squares, in the variant illustrated in Figure 10b) .
  • Figure 11 illustrates a projection exposure apparatus 1 in which a correction element 21 according to the invention is arranged in the projection objective 7. Furthermore, the illumination device 3 of the projection exposure apparatus 1 is designed in such a way that a dipole illumination is realized by means of the illumination device 3. In a projection exposure apparatus 1 configured in this way, the correction element 21 according to the invention exhibits its maximum correction potential on account of the extremely inhomogeneous illumination distribution.
  • Figure 13 shows a further variant of a correction element 21 according to the invention, which exhibits as temperature-regulating elements 40 heating wires which are distributed over the correction element 21 in grid-shaped fashion and which, upon suitable contact- connection, can generate a desired temperature distribution across the correction element 21.
  • Figure 13 furthermore illustrates an infrared source embodied as IR laser 41, by means of which source a delimited, directional infrared beam 42 can be directed onto any desired points on the correction element 21, which leads to local heating of the correction element 21.
  • Local cooling e.g. using a cooling, directed fluid stream
  • the additional elements 33 can also be produced as conductive elements e.g. made from a metallic material or be provided with a conductive layer running in the direction of the optical axis. In this way, given a suitable contact-connection of the additional elements 33, in a double functionality, it is possible both to reduce the convection within the liquid layer 24 and to set a desired temperature distribution in the case of using the conductive regions of the additional elements 33 in the manner of a resistance heating system.
  • Figure 14 shows a further variant for the suppression of convection.
  • the liquid layer 24 is subdivided into the two partial layers 24a and 24b via the separating element 50.
  • the partial layers 24a and 24b are arranged one behind another relative to the light path through the optical correction element 21.
  • the respective thicknesses of the two partial layers 24a and 24b are reduced by comparison with the examples outlined above; in particular, they lie within a range of less than 3 mm, thicknesses of 2 or else 1 mm are advantageous in this case.
  • the subdivision of the liquid layer into a plurality of thinner partial layers has the effect of reducing the convection in the partial layers 24a and 24b also in the direction of the layer plane.
  • the correction effect of the correction element 21 is practically completely retained on account of the unchanged summed total thickness of the liquid layer 24.
  • the variant presented has the advantage that the optical effect of the convection-reducing measures can be kept small; thus, by way of example, a plane-parallel quartz glass plate having a small optical influence can be used as the separating element 50.
  • Figure 15 shows a further possibility for reducing convection.
  • a reduction of the layer thickness of the liquid layer 24 is made possible by virtue of the fact that the latter is thermally insulated from the delimiting elements 22 and 23 by means of the insulating layers 51.
  • the required minimum thickness of the liquid layer 24 also depends, inter alia, on the extent to which there is thermal coupling between the liquid layer 24 and the delimiting elements 22 and 23, respectively. It has essentially been found that, the better the thermal coupling between the liquid layer 24 and the delimiting elements 22 and 23, respectively, an increased thickness of the liquid layer 24 becomes necessary.
  • the insulating layers 51 reduce the heat transfer between the liquid layer 24 and the delimiting elements 22 and 23, respectively, and thus enable a thinner liquid layer 24. In this way it becomes possible to dimension the liquid layer 24 of the order of magnitude of the values presented in connection with Figure 14 and thus, on account of the reduced thickness, largely to prevent convection also in the layer direction.
  • the insulating layer 51 can be configured in such a way that gas bubbles are introduced in that region of the delimiting elements 22 and 23 which faces the liquid layer, the diameter of said gas bubbles being chosen such that the optical influence of the gas bubbles is largely reduced.
  • bubble classes up to 5 x 0.25 shall be permitted, for example. This corresponds to a total area of 1.25 mm 2 . According to ISO 1010-3 it is permitted to distribute this area among more bubbles of an equivalent total area as long as no accumulation occurs in this case.
  • a further variant - illustrated in Figure 16 - for reducing the disturbing influences caused by the convection consists in the liquid that forms the liquid layer 24 being replaced at regular intervals, and therefore in providing for a homogenization of the temperature distribution in the liquid layer 24.
  • the correction element 21 is provided with the inlets and outlets 55, which ensured that the liquid layer 24 is at least partly replaced.
  • the period of time in which the temperature distribution in the liquid layer 24 first forms without the convection exceeding a disturbing degree is utilized for the manipulator effect of the optical correction element.
  • that time window in which, although a compensating temperature distribution has already formed in the liquid layer 24, the convection has not yet exceeded a disturbing degree can advantageously be used for the use of the manipulator.
  • FIG. 16 illustrates by way of example an infrared source embodied as IR laser 41, by means of which source a delimited, directional infrared beam 42 can be directed onto any desired points on the correction element 21 or the liquid layer 24, which leads to local heating of the correction element 21 or the liquid layer 24.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Epidemiology (AREA)
  • Public Health (AREA)
  • Lenses (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Abstract

L'invention concerne un procédé destiné à corriger les aberrations d'images dues à la température dans un système optique. La correction est effectuée à l'aide d'une couche de liquide (24) introduite dans le système optique. La répartition de la température de cette couche de liquide (24) est rendue hétérogène par absorption d'un rayonnement optique utile, ce qui permet de compenser les aberrations d'images. L'invention concerne en outre un élément de correction optique (21) destiné à être utilisé dans ledit procédé, un objectif de projection (7) et un appareil d'exposition par projection (1) comportant ledit élément de correction optique (21).
PCT/EP2008/002693 2007-04-05 2008-04-04 Elément de correction optique, procédé de correction des aberrations d'images dues à la température dans les systèmes optiques, objectif de projection et appareil d'exposition par projection pour la lithographie de semi-conducteurs WO2008122410A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102007016806 2007-04-05
DE102007016806.5 2007-04-05

Publications (2)

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WO2008122410A2 true WO2008122410A2 (fr) 2008-10-16
WO2008122410A3 WO2008122410A3 (fr) 2009-01-29

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PCT/EP2008/002693 WO2008122410A2 (fr) 2007-04-05 2008-04-04 Elément de correction optique, procédé de correction des aberrations d'images dues à la température dans les systèmes optiques, objectif de projection et appareil d'exposition par projection pour la lithographie de semi-conducteurs

Country Status (3)

Country Link
DE (1) DE102008000968A1 (fr)
TW (1) TW200903184A (fr)
WO (1) WO2008122410A2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010133231A1 (fr) * 2009-05-16 2010-11-25 Carl Zeiss Smt Ag Appareil d'exposition par projection destiné à un procédé de lithographie pour semi-conducteurs comprenant un agencement de correction optique
US9377694B2 (en) 2011-06-20 2016-06-28 Carl Zeiss Smt Gmbh Projection arrangement
DE102016218744A1 (de) 2016-09-28 2018-03-29 Carl Zeiss Smt Gmbh Projektionsbelichtungsanlage mit Flüssigkeitsschicht zur Wellenfrontkorrektur

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11474439B2 (en) * 2019-06-25 2022-10-18 Canon Kabushiki Kaisha Exposure apparatus, exposure method, and method of manufacturing article
CN112859543B (zh) * 2021-02-02 2021-12-14 北京理工大学 一种折反式深紫外光刻物镜***设计方法

Citations (3)

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WO2004019128A2 (fr) * 2002-08-23 2004-03-04 Nikon Corporation Systeme optique de projection et procede associe pour la photolithographie, et appareil d'exposition et procede associe
EP1524558A1 (fr) * 2003-10-15 2005-04-20 ASML Netherlands B.V. Appareil lithographique et procédé pour la production d'un dispositif
WO2006053751A2 (fr) * 2004-11-18 2006-05-26 Carl Zeiss Smt Ag Objectif de projection d'une installation d'eclairage de projection microlithographique

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
WO2004019128A2 (fr) * 2002-08-23 2004-03-04 Nikon Corporation Systeme optique de projection et procede associe pour la photolithographie, et appareil d'exposition et procede associe
EP1524558A1 (fr) * 2003-10-15 2005-04-20 ASML Netherlands B.V. Appareil lithographique et procédé pour la production d'un dispositif
WO2006053751A2 (fr) * 2004-11-18 2006-05-26 Carl Zeiss Smt Ag Objectif de projection d'une installation d'eclairage de projection microlithographique

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010133231A1 (fr) * 2009-05-16 2010-11-25 Carl Zeiss Smt Ag Appareil d'exposition par projection destiné à un procédé de lithographie pour semi-conducteurs comprenant un agencement de correction optique
CN102428408A (zh) * 2009-05-16 2012-04-25 卡尔蔡司Smt有限责任公司 包括光学校正布置的用于半导体光刻的投射曝光设备
JP2012527099A (ja) * 2009-05-16 2012-11-01 カール・ツァイス・エスエムティー・ゲーエムベーハー 光学補正構成体を備える半導体リソグラフィ用の投影露光装置
KR20150064251A (ko) * 2009-05-16 2015-06-10 칼 짜이스 에스엠테 게엠베하 광학 교정 배열체를 포함하는 반도체 리소그래피를 위한 투사 노광 장치
KR101626737B1 (ko) * 2009-05-16 2016-06-01 칼 짜이스 에스엠테 게엠베하 광학 교정 배열체를 포함하는 반도체 리소그래피를 위한 투사 노광 장치
US9366977B2 (en) 2009-05-16 2016-06-14 Carl Zeiss Smt Gmbh Semiconductor microlithography projection exposure apparatus
US9377694B2 (en) 2011-06-20 2016-06-28 Carl Zeiss Smt Gmbh Projection arrangement
DE102016218744A1 (de) 2016-09-28 2018-03-29 Carl Zeiss Smt Gmbh Projektionsbelichtungsanlage mit Flüssigkeitsschicht zur Wellenfrontkorrektur
WO2018060126A1 (fr) 2016-09-28 2018-04-05 Carl Zeiss Smt Gmbh Dispositif de lithographie par projection comportant une couche de liquide pour la correction de front d'onde

Also Published As

Publication number Publication date
TW200903184A (en) 2009-01-16
DE102008000968A1 (de) 2008-10-09
WO2008122410A3 (fr) 2009-01-29

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