Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70058—Mask illumination systems
  • G03F7/70191—Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/002—Arrays of reflective systems
• • 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
• • 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
  • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
• • 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
  • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
  • G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements
  • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
  • G02B5/3075—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state for use in the UV
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70058—Mask illumination systems
  • G03F7/70091—Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
  • G03F7/70116—Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
  • G03F7/70566—Polarisation control

Definitions

• the invention relates to an optical system for a microlithographic projection expo- sure apparatus and to a microlithographic exposure method.
• Prior art Microlithographic projection exposure apparatuses are used for producing micro- structured components, such as, for example, integrated circuits or LCDs.
• a projection exposure apparatus comprises an illumination device and a projection lens.
• a substrate e.g. a silicon wafer
• a light-sensitive layer photoresist
• mirror arrangements comprise a multiplicity of micro-mirrors that can be set independently of one another.
• An optical system according to the invention for a microlithographic projection exposure apparatus comprises: - at least one mirror arrangement having a plurality of mirror elements, wherein these mirror elements can be adjusted independently of one another for changing an angular distribution of the light reflected by the mirror arrangement; and a polarization-influencing optical arrangement which is arranged downstream of the mirror arrangement in the light propagation direction; wherein the polarization-influencing optical arrangement reflects a light beam incident on the arrangement in at least two reflections, which do not occur in a common plane, for at least one angular distribution of the light reflected by the mirror arrangement.
• the invention is based on the concept of providing the option for flexibly setting different polarization distributions beyond setting the intensity distribution by virtue of a plurality of reflections, not all lying in a common plane, occurring in a polarization-influencing optical arrangement following the mirror arrangement with the result that a geometric polarization rotation is obtained.
• This polarization rotation can be traced back to a geometric effect known per se and is also referred to as "spin-redirection phase” or “Berry phase”.
• the effect can be traced back to the fact that, in an optical system, the coordinate system for a given polarization state is rotated for skew light beams, i.e. beams which leave the meridional plane, from the entry area to the exit area of the optical system.
• a polarized beam is likewise rotated in its preferred polarization direction, even if there is no optical rotator (i.e., in particular, no linearly birefringent or circularly birefringent or optically active element) in the system and also if there is no polarization rotation due to s/p-splitting or by means of a polarizer.
• optical rotator i.e., in particular, no linearly birefringent or circularly birefringent or optically active element
• the invention makes use of the fact that the light beams incident on the mirror arrangement with mirror elements that can be set independently of one another can in each case be directed to a point in the pupil plane of the optical system by varying the deflection angle respectively set by the mirror elements on different beam paths along the polarization-influencing optical arrangement, with the occurring geometric polarization rotation differing in each case.
• the invention makes use of the fact that the light beams incident on the mirror arrangement with mirror elements that can be set independently of one another can in each case be directed to a point in the pupil plane of the optical system by varying the deflection angle respectively set by the mirror elements on different beam paths along the polarization-influencing optical arrangement, with the occurring geometric polarization rotation differing in each case.
• the polarization-influencing optical arrange- ment reflects a light beam incident on the arrangement in at least three reflections, which do not all occur in a common plane, for at least one angular distribution of the light reflected by the mirror arrangement.
• At least one of these reflections is a total- internal reflection.
• all of these reflections can be total-internal reflections. This allows light losses in the region of the polarization-influencing optical arrangement to be minimized or entirely avoided.
• the polarization-influencing optical arrange- ment consists of an optical element transmissive to light with the work wavelength of the optical system.
• This optical element preferably does not have birefringence (in particular no intrinsic birefringence either and also no stress birefringence either) so that the occurring polarization rotation only, and in a well-defined manner, consists in the form of the above-described geometric polarization rotation.
• the optical element can, in particular, be produced from an optically amorphous material, in particular fused silica (S1O 2 ).
• the polarization-influencing optical arrangement has a substantially rod-shaped geometry.
• the polarization-influencing optical arrangement has a light-entry area, a light-exit area and a plurality of side areas, wherein the reflections at each case occur at one of these side areas.
• some of these side areas can also form a hollow profile within the polarization-influencing optical arrangement.
• the polarization-influencing optical arrangement has at least two mirrors, wherein the reflections at each case occur at one of these mirrors.
• at least one light beam has the same direction after the last one of the reflections and when leaving the polarization- influencing optical arrangement as during incidence on the polarization-influencing optical arrangement.
• the optical system in relation to the light propagation direction, respectively has one deflection device upstream and downstream of the mirror arrangement.
• the deflection device arranged upstream of the mirror arrangement can be formed by a deflection mirror and the deflection device arranged downstream of the mirror arrangement can be formed by the polarization-influencing optical arrangement.
• the invention is not restricted to the application at work wavelengths in the VUV range (less than 250 nm, in particular less than 200 nm, more particularly less than 160 nm). In principle, an implementation in the EUV (i.e. at wavelengths of less than 30 nm, in particular less than 15 nm) is possible.
• the invention furthermore relates to a microlithographic exposure method, in which light, generated by a light source, of an illumination device of a projection exposure apparatus is supplied for illuminating an object plane of a projection lens and in which the object plane is imaged in an image plane of the projection lens by means of the projection lens,
• At least one mirror arrangement which has a plurality of mirror elements that can be adjusted independently of one another for changing an angular distribution of the light reflected by the mirror arrangement, is used in the illumination device and - wherein a light beam reflected by the mirror arrangement is reflected in at least two reflections, which do not occur in a common plane, for at least one angular distribution of the light reflected by the mirror arrangement.
• FIG. 1 shows a schematic illustration for explaining the functional principle of a polarization-influencing optical arrangement utilized in accordance with the invention.
• Figures 2-4 show schematic illustrations for explaining further embodiments of the present invention.
• Figure 5 shows a schematic illustration for explaining the possible design of a microlithographic projection exposure apparatus with an optical system according to the invention.
• the projection exposure apparatus in accordance with Fig. 5 has an illumination device 10 and a projection lens 20.
• the illumi- nation device 10 serves for illuminating a structure-carrying mask (reticle) 30 using light from a light-source unit 1 , which for example comprises an ArF excimer laser for a work wavelength of 193 nm and a beam shaping optical unit generating a parallel bundle of light.
• a light-source unit 1 which for example comprises an ArF excimer laser for a work wavelength of 193 nm and a beam shaping optical unit generating a parallel bundle of light.
• the illumination device 10 and the projection lens 20 are preferably designed for a work wavelength of less than 250 nm, in particular of less than 200 nm, more particularly less than 160 nm.
• the illumination device and the projection lens of the projection exposure apparatus can also be designed for operation in the EUV, i.e. at wavelengths of the less than 30 nm, in particular of less than 15 nm.
• a mirror arrangement 200 and a polarization- influencing optical arrangement 210 are, in particular, components of the illumination device 10.
• the mirror arrangement 200 has - as indicated schematically in e.g. Fig. 2 - a plurality of mirror elements 200a, 200b, 200c, ... that can be adjusted independently of one another for changing an angular distribution of the light reflected by the mirror arrangement 200.
• the mirror elements 200a, 200b, 200c, ... can be tilted, individually in each case, over e.g.
• ⁇ an angular range of -2° to +2°, in particular -5° to +5°, more particularly - 10° to +10°.
• a micro-lens arrangement (not illustrated), which has a multiplicity of micro-lenses for targeted focusing on the mirror elements 200a, 200b, 200c, ... and for reducing or avoiding illumination of a "dead area" and a loss of light between the mirror elements 200a,
• the illumination device 10 has an optical unit 1 1 which, inter alia, comprises a deflection mirror 12 in the depicted example. Downstream of the optical unit 1 1 in the light propagation direction and in the beam path there is a light-mixing device (not illustrated) which can, for example in a manner known per se, have an arrangement of micro-optical elements suitable for obtaining a light mixture and there also is a lens group 14, behind which there is a field plane with a reticle masking sys- tem (REMA) which is imaged onto the structure-carrying mask (reticle) 30 situated in a further field plane by a REMA lens 15 following in the light propagation direction and, as a result thereof, delimits the illuminated region on the reticle.
• a light-mixing device (not illustrated) which can, for example in a manner known per se, have an arrangement of micro-optical elements suitable for obtaining a light mixture and there also is a lens group 14, behind which there is a field plane with a reticle
• the structure-carrying mask 30 is imaged onto a wafer or a substrate 40 provided with 5 a light-sensitive layer by the projection lens 20.
• the projection lens 20 can, in particular, be designed for immersion operation. Furthermore, it can have a numerical aperture NA of greater than 0.85, in particular of greater than 1 .1.
• Fig. 1 initially serves for explaining the principle of a polarization-influencing optical 10 arrangement 1 10 employed in accordance with the invention.
• the polarization-influencing optical arrangement 1 10 has three mirrors 1 10a, 1 10b and 1 10c, by means of which a beam S incident on the polarization-influencing optical arrangement 1 10 from the mirror arrangement (not illustrated in Fig. 1 ) situated upstream thereof, as del s scribed above, experiences three successive reflections by means of which, overall, a geometric rotation of the polarization direction of the beam S is achieved.
• the beam S is initially reflected in the negative y- direction in relation to the plotted coordinate system (i.e. downward within the 20 plane of the drawing) at the first mirror 1 10a, subsequently reflected in the positive x-direction (i.e. perpendicularly out of the plane of the drawing) at the second mirror 1 10b and finally reflected in the positive z-direction (i.e. toward the right in the plane of the drawing) at the third mirror 1 10c, whereupon the beam S once again has the original propagation direction when leaving the polarization-influencing op-
• the polarization direction of the beam S was rotated geometrically (and, in particular, without the use of linear or circular birefringence) by 90° compared to the input polarization direction (namely from an original "x-polarization", i.e. a linear polarization with an oscillation plane of the electric field strength vector extending along the x-axis, to an ultimately obtained y-
• polarization i.e. a linear polarization with an oscillation plane of the electric field strength vector extending along the y-axis
• the invention is not restricted to the three reflections which occur in the example described above.
• the invention is not restricted to the "pure" generation of s- or p-polarization, plotted in each case in Fig. 1 , and so other skew reflections which obtain different output polarizations in each case can also occur in fur- ther exemplary embodiments.
• this embodiment is, in principle, also realizable in an optical system designed for oper- ation in the EUV.
• the polarization-influencing optical arrangement - as described below with reference to Fig. 2 ff. - can also consist of an optical element transmissive to light of the respective work wavelength of the optical system.
• Fig. 2 shows a schematic illustration for explaining a further embodiment of the invention.
• a polarization-influencing optical arrangement 210 arranged downstream of the mirror arrangement 200 having the mirror elements 200a, 200b, 200c, ... that can be adjusted independently of one another in relation to the light propagation direction (extending along the z-direction in the plotted coordinate system), is embodied as a rod and made of material such as fused silica (S1O2) which is transmissive to light at the work wavelength (e.g. approximately 193 nm), which material moreover does not, where possible, have birefringence (i.e., in particular, no stress birefringence or intrinsic birefringence ei- ther).
• S1O2 fused silica
• light beams which enter the rod forming the polarization- influencing optical arrangement 210 through an end area, can pass through the rod along different beam paths depending on the deflection angles set by the mirror elements 200a, 200b, 200c, ... .
• a beam Si reflected at the mirror element 200c it is possible, for example, for a beam Si reflected at the mirror element 200c to reach one and the same location in the pupil plane or one and the same location on an optical element 240 arranged in the pupil plane along a direct beam path, denoted by "A" in Fig. 2 (i.e.
• the respectively applicable boundary angle for total-internal reflection relating to the normal in relation to the reflecting area should be obtained or exceeded for every light beam (with the exception of at the light exit area) incident on the side areas or interfaces within the transmissive optical element forming the polarization-influencing optical ar- rangement 210.
• Fig. 3a-c show further embodiments of a polarization-influencing optical arrangement which can be employed in an optical system according to the invention.
• the polarization-influencing optical arrangement in this case has a light entry area, a light exit area and a plurality of side areas, wherein the reflections at each case occur at one of these side areas.
• the side areas 320a- 320f moreover form a hexagonal hollow profile 325 within the polarization- influencing optical arrangement 320
• the side areas 330a-330d form a square hollow profile 335 within the polarization-influencing optical arrangement 330.
• a beam profile which is indicated in a purely exemplary manner in Fig. 3a
• light respectively enters the end area (arranged in the xy- plane) of the transmissive element which forms the polarization-influencing optical arrangement and is shaded in the illustration during the operation of the optical system
• the mirror elements 200a, 200b, 200c, ... of the mirror arrange- ment 200 (which are not plotted in Fig. 3a-c but have a design analogous to Fig. 2 and are arranged upstream of the transmissive element in relation to the light propagation direction) can be used to set different entry angles (i.e. different angles of inclination to the z-axis extending perpendicular to the entry area).
• a specific desired output polarization of the light incident on a specific location in the pupil plane to establish, e.g. by means of simulation, a succession of reflections suitable for generating this polarization state by means of a geometric polarization rotation and, in turn, the deflection suitable for this to be brought about by the mirror arrangement 200, whereupon the actuation of the mirror elements 200a, 200b, 200c, ... of the mirror arrangement 200 can be undertaken in an appropriate manner (e.g. by the actuation unit 205).
• a beam "S" entering the transmissive optical element through the end area 310a is successively reflected on the side areas 310b, 310c and 31 Od, before it emerges through the light exit area.
• the entry angle set by the mirror elements 200a, 200b, 200c, ... of the mirror arrangement 200 when light enters the respective transmissive element forming the polarization-influencing optical arrangement is, also in accordance with Fig. 3a-c, prefera- bly selected such that the reflections occurring at the interfaces are in each case total-internal reflections, resulting in all light entering into the transmissive element remaining within this element over the course of the occurring reflections while avoiding light losses and only emerging from the element after the last reflection.
• the respectively applicable boundary angle for total-internal reflec- tion relating to the normal in relation to the reflecting area should, also in accordance with Fig. 3a-c, be obtained or exceeded for every light beam (with the exception of at the light exit area) incident on the side areas or interfaces within the relevant transmissive optical element forming the polarization-influencing optical arrangement.
• the respective entry angles set by the mirror elements 200a, 200b, 200c, ... of the mirror arrange- ment 200 to provide different successive reflections at the interfaces to the respectively surrounding optical thinner medium and hence to provide different geometric polarization rotations.
• the successive reflections which occur in accordance with Fig. 3a-c and are employed for geometric polarization rotation can also be realized by virtue of the polarization-influencing optical arrangement, deviating from Fig. 3a-c, being embodied without material in the region respectively shaded and with reflecting areas or mirrors forming the interfaces in each case (which then as it were delimit a hollow tube with an arbitrary predetermined cross section).
• this embodiment can then, in principle, analogous to Fig. 2, also be realized in an optical system designed for operation in the EUV.
• the entry angle into the polarization-influencing optical arrangement set by the mirror elements 200a, 200b, 200c, ... of the mirror arrangement 200 is preferably selected such that the reflections occurring at the reflecting areas of the polarization-influencing optical arrangements occur as completely as possible or with minimal s/p-split, for which purpose, in turn, the angles of incidence on the respective reflecting areas should have values which are as small as possible (i.e. grazing incidence), e.g. less than 30°, in particular less than 20°, more particularly less than 20° in relation to the reflecting area.
• a suitable coating can be provided on the relevant reflecting areas for minimizing the s/p-split or for maximizing the reflections at the used angle range in embodiments of the invention, which coating can be embodied in the form of any known HR layer when the optical system is designed for VUV (e.g. for a work wavelength of less than 250 nm, in particular less than 200 nm) and e.g. as ruthenium coating or as molybdenum/silicon multiple layer for a work wavelength in the EUV.
• Fig. 4a shows a schematic illustration for explaining a further possible application of the invention in an illumination device which likewise has a mirror arrangement
• a deflection device 401 , 402 is respectively provided upstream and downstream of the mirror arrangement 400 in the light propagation direction, wherein the deflection device 401 arranged upstream of the mirror arrangement 400 is formed by a deflection mirror and wherein the deflection device 402 arranged downstream of the mirror arrangement 400 is formed by a polariza- tion-influencing optical arrangement analogous to the embodiments described with reference to Fig. 3a-c.
• Exemplary embodiments of such a polarization-influencing optical arrangement, which simultaneously acts as deflection device 402 are illustrated schematically in Fig. 4b and 4c.
• the deflection device 401 arranged upstream of the mirror arrangement 400 deflects the illumination light initially propagating along the optical system axis OA (i.e. in z-direction) in the direction toward the mirror arrangement 400 by means of reflection, whereupon - after reflection at the mirror elements 400a, 400b, 400c, ... of the mirror arrangement 400 - there once again is a deflection in a direction approximately parallel to the optical system axis OA to the additional components 403, ... provided in the illumination device by a reflection at the second deflection device 402 (or as a result of the beam deflection by the polarization-influencing optical arrangement 410, 420 in accordance with Fig. 4b, 4c).
• the mirror elements 400a, 400b, 400c, ... of the mirror arrangement 400 can be adjusted by an actuation unit 405 in order thereby to provide different successive reflections within the polarization- influencing optical arrangement forming the second deflection device 402 by varying the entry angles and thereby create the option for flexibly setting different polarization distributions in a subsequent plane, e.g. in the pupil plane.

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

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• 2012
  • 2012-09-28 DE DE102012217769.8A patent/DE102012217769A1/de not_active Withdrawn
• 2013
  • 2013-09-19 KR KR1020157005671A patent/KR101699639B1/ko not_active Expired - Fee Related
  • 2013-09-19 WO PCT/EP2013/069458 patent/WO2014048828A1/en not_active Ceased
  • 2013-09-19 JP JP2015532407A patent/JP6140290B2/ja active Active
• 2015
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