Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/08—Mirrors
  • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• • 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
  • G03F7/70233—Optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection systems
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/70591—Testing optical components
• • 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
  • 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
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
  • G21K1/06—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators
  • G21K1/062—Devices having a multilayer structure
• • G—PHYSICS
  • 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
  • G02B26/06—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the phase of light

Definitions

• MICROLITHOGRAPHIC PROJECTION EXPOSURE APPARATUS METHOD FOR VARYING AN OPTICAL WAVEFRONT IN A CATOPTRIC LENS OF SUCH AN APPARATUS
• Microlithographic projection exposure apparatuses are used to transfer structures contained in a mask or formed thereon to a photoresist or some other light-sensitive layer.
• the most important optical components of a projection exposure apparatus are a light source, an illumination system, which conditions projection light generated by the light source and directs it onto the mask, and a lens, which images that section of the mask which is illuminated by the illumination system onto the light-sensitive layer.
• EUV projection exposure apparatuses Such apparatuses are often referred to as EUV projection exposure apparatuses.
• EUV projection exposure apparatuses there are no optical materials which have a sufficiently high transmissitivity for such short wavelengths. Therefore, in EUV projection exposure apparatuses the lens elements and other refractive optical elements that are cus- tomary at longer wavelengths are replaced by mirrors, and also the mask contains a pattern of reflective structures. Lenses containing exclusively mirrors as imaging optical elements are designated as catoptric lenses.
• Imaging aberrations of lenses are often described as a deviation of a usually measured real optical wavefront from an ideal optical wavefront. Such deviations, also referred to as wavefront deformations, can be decomposed into individual portions e.g. as a series expansion. In this case, in par- ticular, a decomposition according to Zernike coefficients has proved to be suitable since the individual terms of the decomposition can be assigned directly to specific Seidel imaging aberrations such as astigmatism or coma.
• One approach for correcting short-wave wavefront deformations consists in locally removing the surface on suitable mirrors in order to change the form of the mirror and thereby to re-lude or influence the wavefront deformations such that they can be corrected more easily by the manipulators already mentioned.
• Another approach consists not in removing material from the mirror surface, but rather locally compacting the mirror sub- strate below the reflective coating, as is described in
• a processing beam e.g. an electron beam or a high-energy light beam
• the processing beam penetrates through the reflective coating without appreciably interacting therewith, and leads to compaction in the underlying region of the mirror substrate.
• the associated local contraction of the substrate finally brings about the desired deformation of the mirror.
• any type of postprocessing initially requires the incorporation of the mirror into the lens, in order to determine the need for correction and the required postprocessing. If the relevant mirror is then demounted from the lens, post- processed and later incorporated again, then conditions present when ascertaining the need for correction can no longer be totally reproduced.
• the optical properties of the lens elements are taken into account such that those radiation intensities which are required for a local material shrinkage and/or increasing the refractive index occur only on a desired correction lens ele- ment .
• the other lens elements through which the radiation passes are not processed by the processing radia ⁇ tion .
• the access channel be a light channel that is provided anyway for the passage of the projection light. It is even more expedient, however, if the access channel is provided in addition to such a light channel .
• the invention additionally relates to a lens comprising a mirror, a processing head, which is configured to emit a processing beam, and comprising a moving device, which is configured to arrange the processing head at different loca- tions over an area of the mirror such that the processing beam brings about a permanent change in the form of the mirror .
• the distance between the processing head and the area of the mirror does not exceed a maximum processing distance of 10 mm.
• the invention furthermore relates to a method for varying an optical wavefront in a lens, comprising the following steps: a) assembling a catoptric lens from a plurality of mirrors; b) adjusting the mirrors; c) directing a processing beam onto an area of a mirror, whereby the form thereof changes permanently, wherein the mirror is neither the first nor the last mirror of the lens in the beam path of the lens.
• Figure 1 shows, in a perspective and highly schematic illustration not to scale, the basic construction of a microlitho- graphic projection exposure apparatus according to the inven- tion, said apparatus being designated in its entirety by 10.
• the projection exposure apparatus 10 serves to project reflective structures 12 arranged on a side of a mask 14 that faces downward in Figure 1 to a light-sensitive layer 16.
• the light-sensitive layer 16 which can be, in particular, a photoresist (also called resist) , is carried by a wafer 18 or some other substrate.
• the latter has the effect that the entering light beams converge in an image plane of the lens 26 at field points.
• the field points in the object plane from which the light beams proceed, and the field points in the image plane at which said light beams converge again are in this case in a relationship with one another which is designated as optical conjugation.
• a light beam is indicated schematically and designated by 28.
• the aperture angle of the light beam 28 upon entering into the lens 26 is a measure of the numerical aperture NA thereof.
• the image-side numerical aperture NA of the lens 26 is enlarged by the reciprocal of the imaging scale ⁇ .
• the latter finally focuses the light beam 28 into a conjugate image point in the image plane 32.
• the mirrors Ml to M6 were supplemented by the parts indicated by dashed lines in Figure 2, then the reflective surfaces of the mirrors thus supplemented would be rotationally symmetrical with respect to the optical axis OA of the lens 26.
• the beam path described above could not be realized with such completely rotationally symmetrical mirrors, however, since the mirrors would then partly block the light path. Therefore, the mirrors Ml to M6 have the forms indicated by solid lines.
• the lens 26 has a first pupil surface 34, which is situated in or in direct proximity to the surface of the second mirror M2.
• the processing head 44 contains an electron gun that is conventional per se, such as are used for example in X-ray sources.
• an electron gun usually comprises an electron source, e.g. an incandescent cathode, a Wehnelt cylinder and an acceleration anode in order to accelerate the electrons released by the incandescent cathode.
• the energy of the electrones emitted by the process- ing head 44 is preferably in the range of between 5 keV and 80 keV, and in particular between 40 keV and 50 keV.
• the energy which the emitted electrons should ideally have is dependent, inter alia, on the material of which the substrate of the mirrors M2, M3 consists.
• the lens 26 is assembled and adjusted.
• the imaging properties of the lens 26 are generally measured iteratively. This can be done, by way of example, in a manner known per se, by interferrometrically determining the optical wavefront in the image plane 32 of the lens 26.
• the position of the mir- rors Ml to M6 is varied such that the imaging aberrations are minimized.
• manipulators if present, can also be used, which deform one or more of the mirrors Ml to M6 in a targeted manner in order to further reduce the wavefront deformations in this way.
• residual imaging aberrations are often short-wave wavefront deformations that are described by higher terms in a decomposition of the wavefront deformations according to Zernike coefficients.
• Contributions to the residual imaging aberrations which are independent of the field position can be reduced by targeted postprocessing of the second mirror M2 ar- ranged in the first pupil plane 34.
• the aim of the postprocessing is to deform the second mirror M2 such that the remaining residual imaging aberrations are reduced or converted into longer-wave imaging aberrations that can be corrected with the aid of other manipulators in the abovementioned ad- justment process.
• FIG 4b shows the second mirror M2 during a processing operation with the aid of the processing device 42.
• the processing head 44 is situated at a processing distance d from the reflective coat- ing 58 that is less than 10 mm.
• a processing distance d is necessary in order that the divergent electron beam 65 generates a sufficiently small beam spot on the second mirror M2.
• the high-energy electrons penetrate through the thin reflective coating 58 without appreciably interacting therewith.
• the high- energy electrons are absorbed and bring about there a local compaction of the mirror substrate 54.
• This compaction is associated with a deformation 66 of the optical area 56 and of the reflective coating 58 carried thereby, as shown by Figure 4c.
• This local deformation 66 produces the desired correction of the wavefront and thus contributes to the improvement of the imaging properties of the lens 26.
• FIG. 5 shows at the top an excerpt from a lens 26, in whose support structure 47 for sup- porting the mirrors Ml to M6 a light channel 68 is formed, which is provided for the passage of the EUV projection light.
• the processing head 44 is brought to the desired position relative to the second mirror M2 with the aid of the moving device 46 and the processing is performed with the aid of the processing beam 65.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Nanotechnology (AREA)
• Chemical & Material Sciences (AREA)
• Optics & Photonics (AREA)
• Public Health (AREA)
• Theoretical Computer Science (AREA)
• Mathematical Physics (AREA)
• Health & Medical Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Epidemiology (AREA)
• Crystallography & Structural Chemistry (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
• Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
• Lenses (AREA)

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• 2012
  • 2012-07-12 DE DE102012212194.3A patent/DE102012212194B4/de active Active
• 2013
  • 2013-07-04 WO PCT/EP2013/001962 patent/WO2014008994A1/en active Application Filing
  • 2013-07-09 TW TW102124555A patent/TWI610141B/zh active

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