EP1721217A2 - Systeme permettant de reduire la coherence d'un rayonnement laser - Google Patents

Systeme permettant de reduire la coherence d'un rayonnement laser

Info

Publication number
EP1721217A2
EP1721217A2 EP05707555A EP05707555A EP1721217A2 EP 1721217 A2 EP1721217 A2 EP 1721217A2 EP 05707555 A EP05707555 A EP 05707555A EP 05707555 A EP05707555 A EP 05707555A EP 1721217 A2 EP1721217 A2 EP 1721217A2
Authority
EP
European Patent Office
Prior art keywords
resonator body
partial
projection exposure
laser beam
laser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05707555A
Other languages
German (de)
English (en)
Inventor
Nils Dieckmann
Manfred Maul
Damian Fiolka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Carl Zeiss SMT GmbH
Original Assignee
Carl Zeiss SMT GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carl Zeiss SMT GmbH filed Critical Carl Zeiss SMT GmbH
Publication of EP1721217A2 publication Critical patent/EP1721217A2/fr
Withdrawn legal-status Critical Current

Links

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
    • G03F7/20—Exposure; Apparatus therefor
    • 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
    • G03F7/70583—Speckle reduction, e.g. coherence control or amplitude/wavefront splitting
    • 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

Definitions

  • the invention relates to a system for reducing the coherence of a laser radiation emitting wavefronts, in particular for a projection objective in semiconductor lithography, a first partial beam being partially reflected by the laser beam impinging on a surface of a resonator body and a second partial beam entering the resonator body and after several total reflections at least approximately in the area of the entry point, it emerges from the resonator body and is passed on together with the first partial beam to an illumination plane.
  • the invention also relates to a projection exposure system with a laser as a light source, an illumination system and a projection lens.
  • the present invention has for its object to provide a system with which the lighting homogeneity can be improved even further.
  • this object is achieved in that the resonator body is designed such that, in addition to the division into partial beams, the wave fronts of at least one partial beam are modulated during a laser pulse, the partial beams reflected on the resonator body and those entering the resonator body after the resonator body are superimposed and the resonator body is provided with a phase plate with different local phase distribution.
  • the wave fronts of the laser radiation are also modulated according to the invention.
  • a significant increase in lighting homogeneity can be achieved by averaging over several speckle distributions.
  • the combination of temporally staggered wave fronts according to the invention, which is additionally modulated and thus receives different phase distributions, allows a very high degree of homogeneity to be achieved by means of averaged speckle patterns.
  • a phase plate, which is attached in the resonator body, is suitable for this.
  • the resonator body is designed as a prism with at least five corners. It was found that, in comparison to a resonator body with 3 corners, at the generally used wavelengths of the laser beams, in particular in the VUV range (vacuum ultraviolet spectral range) or shorter, deflection angles which are too steep result in the prism, so that it does not Total reflections occur, but partial exits with corresponding light losses.
  • VUV range vacuum ultraviolet spectral range
  • the resonator body with 3 corners at the generally used wavelengths of the laser beams, in particular in the VUV range (vacuum ultraviolet spectral range) or shorter, deflection angles which are too steep result in the prism, so that it does not Total reflections occur, but partial exits with corresponding light losses.
  • VUV range vacuum ultraviolet spectral range
  • the resonator body is designed as a prism with at least five corners. It was found that, in comparison to a resonator body with 3 corners, at the generally used wavelengths of the laser beams
  • the thickness of the phase plate is different, then spatially offset wavefronts result. Different changes in thickness - in relation to a direction transverse to the beam direction - should occur at a distance which corresponds to the order of magnitude of the spatial coherence length of the laser radiation which should be modulated through.
  • the phase plate is designed as a diffractive optical element (DOE) which is operated in the zeroth diffraction order.
  • DOE diffractive optical element
  • a diffractive optical element in the first or even a higher diffraction order is normally used.
  • the diffractive optical element (DOE) in the zeroth diffraction order will be used, where the laser light passes through unbroken.
  • Another option is to use a diffuser as a phase plate.
  • the modulation of a wavefront according to the invention can also be achieved in that the resonator body, e.g. the prism with at least five corners is asymmetrical. This can e.g. by an asymmetrical, i.e. non-mirror-symmetrical formation of at least one side of the prism.
  • Another solution, or a combination with an asymmetrical resonator body is that the beam guidance of the laser beam is selected such that the center of gravity beam hits the resonator body off-center. In this case, modulations of the wavefront are also created when the partial beam circulates in the resonator body.
  • the possible uses can be increased further, since the angle dependency can be at least partially reduced.
  • the entry angle can thus be varied through the divider layer and thus also the ratio of the reflected partial beam and that entering the resonator body Partial beam.
  • the divider layer can be of different thicknesses and / or not homogeneous.
  • a dielectric layer with a division ratio of 33: 67 or 1/3: 2/3 can advantageously be used as the divider layer.
  • FIG. 1 shows a schematic structure of a projection exposure system with a light source, an illumination system and a projection lens
  • FIG. 2 pentagonal prism as a resonator body with a phase plate
  • FIG. 3a shows a cross section through the phase plate according to FIG. 2;
  • FIG. 3b shows a cross section through a further embodiment of a phase plate
  • Figure 4 shows a pentagonal prism with two asymmetrical sides
  • Figure 5 shows a pentagonal prism with a divider layer on one surface.
  • a projection exposure system 1 has a light source 2 in the form of a laser
  • Illumination system 3 for illuminating a field in a Level 4, in which a structure-bearing mask 4a is arranged, and a projection objective 5 for imaging the structure-bearing mask 4a in level 4 onto a light-sensitive substrate 6.
  • the projection lens 5 has a plurality of optical elements 7 in its housing 8.
  • the projection exposure system 1 is used to produce semiconductor components, such as computer chips.
  • a resonator body 9, 9 ' is arranged between the laser 2 and the illumination system 3 in order to reduce the, in particular temporal, coherence of a laser radiation 10 from the laser 2.
  • FIG. 2 shows a pentagonal prism as resonator body 9
  • a lambda / 2 plate 18 is used to adjust the degree of polarization (between unpolarized and linearly polarized) of the laser beam 10.
  • the laser beam 10 impinging on a surface 11 of the prism 9 is divided into a first partial beam 10a which reflects on the surface 11 and a partial beam 10b which enters the resonator body 9 and there after several total reflections at the entry point again out of the resonator body 9 emerges and is combined there with the first partial beam 10a.
  • Both partial beams are then fed to an illumination level, in this case level 4 with the structure-bearing mask.
  • a phase plate 12 protrudes into the prism 9 is introduced into the prism 9 in such a way that the circulating partial beam 10b, which approximately meets perpendicularly with a front surface 13 of the phase plate 12, must penetrate it.
  • the phase plate 12 causes a different local phase distribution.
  • the phase plate 12 has a different thickness, as can be seen from the enlarged cross-sectional representations according to FIGS. 3a and 3b.
  • the different thicknesses of the phase plate 12 vary in width s in the transverse direction to the beam direction. The greatest width s should be - depending on the laser used and its wavelength - in the order of the spatial coherence length of the laser radiation used.
  • the value for s is between 0.05 and 1 mm, whereby a possible beam expansion increases the value accordingly.
  • the base thickness of the phase plate b can be in the range of 500 ⁇ m.
  • the distribution of the width differences s and the thickness differences a should be as random as possible, so that a relatively random phase distribution on the wavefront is also obtained.
  • the optical path lengths differ locally and, in the case of the reunited partial beams 10a and 10b after the resonator body 9, correspondingly different partial beams are obtained, which are also modulated with respect to the wavefront.
  • the individual pulses can be so short in their duration and in phase distribution that there is no longer any interference capability.
  • the structure of the phase plate 12 is made tapered or prism-like, whereby an improved beam expansion is achieved.
  • reflection angles are greater than 37 degrees, which means that total reflections occur inside.
  • the exemplary embodiment shown was designed so that all total reflection angles are identical and are approximately 55 degrees.
  • the crystal orientation of the CaF 2 prism 9 is selected such that the first (100) crystal plane forms an angle of 45 ° with the light entry plane of the entry or surface 11 and is perpendicular to the side surface 14.
  • the second (100) crystal plane lies parallel to the side surface 14 of the prism 9.
  • the --- intrinsic birefringence which is significant at the wavelength of 157 nm and 193 nm, does not affect the polarization of the circulating beam if the light at the entrance obex surface 11 is linearly polarized and the direction of oscillation of the electrical Field strength vector is parallel (p-polarized) or perpendicular (s-polarized) with respect to the plane of incidence.
  • the light emerges from the prism 9 again in s or p polarization.
  • the crystal orientation is not important and the prism 9 made of CaF 2 can be oriented as desired.
  • a corresponding possibility consists in producing the block from MgF 2 (transparent at 157 nm and 193 nm, strongly birefringent). It is about. unpolarized Light at the entrance, then the crystal orientation with regard to the prism surfaces can also be chosen arbitrarily.
  • the crystal orientation must be chosen so that the direction of oscillation of the incident electric field strength vector parallel to the fast ( Direction with extraordinary refractive index) or slow (direction with ordinary refractive index) crystal axis.
  • a diffractive optical element can be used as the phase plate 12, which is optimized to the zero order of diffraction, in which incident light passes undeflected.
  • a diffusing screen can also be used as the phase plate 12.
  • FIG. 4 shows a prism in a pentagonal shape, an offset being present or the prism body being asymmetrical.
  • one side namely the first side 15, on which the partial beams 10b impinge are shifted downward by the distance d.
  • the distance d can be of the order of 0.1 mm.
  • phase plate 12 (shown in dashed lines in FIG. 4) can also be used 2, which is even more variable with respect to the modulation of wave fronts.
  • FIG. 5 shows an embodiment of a prism 9, also in a pentagonal shape, a divider layer 17 being applied to the entrance surface 11.
  • the divider layer can e.g. a dielectric layer with a split ratio of 1/3: 2/3.
  • the splitter layer has the task of influencing the entry angle of the partial beam 10b into the prism 9. This can be chosen according to the design and the material of the divider layer as desired.
  • the divider layer also has a different thickness, modulation of the wavefront is also achieved in a manner similar to that of the phase plate (shown in broken lines in FIG. 5). The same is possible through an inhomogeneous or non-homogeneous formation of the divider layer.
  • FIGS. 2, 4 and 5 for generating different wave fronts can be used both separately and in any combination with one another.

Landscapes

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

Abstract

L'invention concerne un système permettant de réduire la cohérence d'un rayonnement laser (10b) émetteur de fronts d'onde, en particulier pour un objectif de projection en lithographie de semi-conducteurs, un premier faisceau partiel (10a) étant partiellement réfléchi du faisceau laser (10) incident sur une surface (11) d'un corps résonateur (9). Un second faisceau partiel (10b) pénètre dans le corps résonateur (9) puis ressort du corps résonateur (9) au moins approximativement dans la zone du point d'entrée après plusieurs réflexions totales. Enfin, les deux faisceaux partiels (10a et 10b) sont transmis en commun à un plan d'éclairage. Le corps résonateur (9) est conçu, de sorte qu'outre le partage en faisceaux partiels (10a, 10b), les fronts d'onde d'au moins un faisceau partiel (10b) sont modulés pendant une impulsion laser, les faisceaux partiels (10a, 10b), réfléchis sur le corps résonateur (9) et pénétrant dans ce dernier, étant superposés après le corps résonateur (9) et ce corps résonateur (9, 9') étant pourvu d'une lame de phase (12) à distribution de phase locale différente.
EP05707555A 2004-02-26 2005-02-22 Systeme permettant de reduire la coherence d'un rayonnement laser Withdrawn EP1721217A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102004009239 2004-02-26
PCT/EP2005/001797 WO2005083511A2 (fr) 2004-02-26 2005-02-22 Systeme permettant de reduire la coherence d'un rayonnement laser

Publications (1)

Publication Number Publication Date
EP1721217A2 true EP1721217A2 (fr) 2006-11-15

Family

ID=34894863

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05707555A Withdrawn EP1721217A2 (fr) 2004-02-26 2005-02-22 Systeme permettant de reduire la coherence d'un rayonnement laser

Country Status (5)

Country Link
US (1) US7593095B2 (fr)
EP (1) EP1721217A2 (fr)
JP (1) JP4769788B2 (fr)
KR (1) KR101109354B1 (fr)
WO (1) WO2005083511A2 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5622126B2 (ja) * 2005-11-15 2014-11-12 株式会社ニコン 面位置検出装置、露光装置、およびデバイスの製造方法
JP5622068B2 (ja) 2005-11-15 2014-11-12 株式会社ニコン 面位置検出装置、露光装置、およびデバイスの製造方法
US7948606B2 (en) * 2006-04-13 2011-05-24 Asml Netherlands B.V. Moving beam with respect to diffractive optics in order to reduce interference patterns
US7649676B2 (en) * 2006-06-14 2010-01-19 Asml Netherlands B.V. System and method to form unpolarized light
NL2004483A (nl) * 2009-05-26 2010-11-30 Asml Holding Nv Pulse stretcher with reduced energy density on optical components.
CN112585542A (zh) * 2018-08-22 2021-03-30 Asml荷兰有限公司 脉冲展宽器及方法
WO2023186325A1 (fr) * 2022-04-01 2023-10-05 SLM Solutions Group AG Procédé de fonctionnement de système de rayonnement, système de rayonnement et appareil pour la fabrication de pièce tridimensionnelle

Family Cites Families (9)

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Publication number Priority date Publication date Assignee Title
JP2590510B2 (ja) 1988-02-03 1997-03-12 株式会社ニコン 照明装置
JP2770984B2 (ja) * 1989-06-08 1998-07-02 キヤノン株式会社 照明装置，投影露光装置及び素子製造方法
US5153773A (en) * 1989-06-08 1992-10-06 Canon Kabushiki Kaisha Illumination device including amplitude-division and beam movements
JP2969718B2 (ja) * 1990-01-20 1999-11-02 キヤノン株式会社 照明装置及びそれを用いた回路の製造方法
DE19508754C2 (de) * 1995-03-10 1999-06-02 Ldt Gmbh & Co Verfahren und Vorrichtung zum Vermindern von Interferenzen eines kohärenten Lichtbündels
US6238063B1 (en) 1998-04-27 2001-05-29 Nikon Corporation Illumination optical apparatus and projection exposure apparatus
WO2000008339A1 (fr) * 1998-08-06 2000-02-17 Mannesmann Rexroth Ag Hydrotransformateur
DE19959742A1 (de) * 1999-12-10 2001-06-13 Zeiss Carl System zur Kompensation von Richtungs- und Positionsschwankungen eines von einem Laser erzeugten Lichtes
TW561254B (en) * 2001-09-26 2003-11-11 Nikon Corp Aberration measuring device, aberration measuring method, regulation method for optical system, and exposure system provided with optical system regulated by the regulation method

Non-Patent Citations (1)

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Title
See references of WO2005083511A2 *

Also Published As

Publication number Publication date
WO2005083511A2 (fr) 2005-09-09
WO2005083511A3 (fr) 2005-12-01
US7593095B2 (en) 2009-09-22
US20070206381A1 (en) 2007-09-06
JP4769788B2 (ja) 2011-09-07
JP2007528595A (ja) 2007-10-11
KR20060129502A (ko) 2006-12-15
KR101109354B1 (ko) 2012-01-31

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