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WO2001041269A1 - Laser excimere ou fluor moleculaire a bande tres etroite - Google Patents

Laser excimere ou fluor moleculaire a bande tres etroite Download PDF

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Publication number
WO2001041269A1
WO2001041269A1 PCT/EP2000/011678 EP0011678W WO0141269A1 WO 2001041269 A1 WO2001041269 A1 WO 2001041269A1 EP 0011678 W EP0011678 W EP 0011678W WO 0141269 A1 WO0141269 A1 WO 0141269A1
Authority
WO
WIPO (PCT)
Prior art keywords
laser
grating
resonator
line
narrowing
Prior art date
Application number
PCT/EP2000/011678
Other languages
English (en)
Inventor
Jürgen KLEINSCHMIDT
Peter Heist
Uwe Stamm
Wolfgang Zschocke
Original Assignee
Lambda Physik Ag
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 Lambda Physik Ag filed Critical Lambda Physik Ag
Priority to JP2001542432A priority Critical patent/JP2004503075A/ja
Publication of WO2001041269A1 publication Critical patent/WO2001041269A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1838—Diffraction gratings for use with ultraviolet radiation or X-rays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/22—Gases
    • H01S3/223—Gases the active gas being polyatomic, i.e. containing two or more atoms
    • H01S3/225—Gases the active gas being polyatomic, i.e. containing two or more atoms comprising an excimer or exciplex
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/08004—Construction or shape of optical resonators or components thereof incorporating a dispersive element, e.g. a prism for wavelength selection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
    • H01S3/0811—Construction or shape of optical resonators or components thereof comprising three or more reflectors incorporating a dispersive element, e.g. a prism for wavelength selection
    • H01S3/0812—Construction or shape of optical resonators or components thereof comprising three or more reflectors incorporating a dispersive element, e.g. a prism for wavelength selection using a diffraction grating

Definitions

  • narrowed spectral emission band are particularly useful in
  • Such lasers include KrF-, ArF-, XeCI-, XeF- and F 2 -lasers, which
  • narrowed output beams includes a resonator, a discharge chamber
  • these lasers can be spectrally very broad (e.g., having a linewidth
  • microlithography provides an output beam with specified narrow
  • spectral linewidth It is desired that parameters of this output beam such as wavelength, linewidth, and energy, energy stability and
  • linewidth is generally achieved through the use of a linewidth
  • line-narrowing module consisting most of
  • a line-narrowing module typically functions to disperse
  • dispersion or beam expansion meaning that the dispersion or
  • laser systems can be broadly classified into three general groups:
  • Broad band excimer lasers do not have any line narrowing
  • FIG. 1 A schematically illustrates a typical broad band
  • the laser resonator includes a highly reflective
  • preionization unit (not shown) and containing a gain medium, and a
  • the dispersive prism or prisms are typically located between the
  • the other side of the laser chamber is typically a partially reflective
  • narrowed laser is reduced for a KrF or ArF laser, e.g., from around
  • the semi-narrow band laser may be
  • Fig. 1 B schematically illustrates an example of a semi-narrow
  • the laser includes a highly reflective mirror ( 1 0), a laser
  • dispersive prism ( 1 8) is inserted into the resonator between the laser
  • the dispersive prisms referred to above further includes a
  • the line-narrowing unit may comprise a Littrow
  • echelle-type blazed reflection grating having a
  • a plurality of beam expanding prisms are used to magnify
  • One or more etalons may also be added for further line narrowing
  • narrow band lasers are used in combination with refractive
  • the expansion ratio is limited by a limitation on size of the prisms that can practically be used in the beam expander
  • fine tuning such as by pressure tuning or using piezoelectric
  • a diffraction grating typically includes a plate or film
  • Diffraction gratings are
  • Diffraction gratings may also be formed in a
  • Diffraction gratings may be made by actually engraving each line
  • ruled gratings generally are of very high quality and very expensive.
  • Such gratings are used as masters from which copy or
  • replica gratings are made. Replica gratings are practically as serviceable while being substantially less inexpensive. The
  • interference between a pair of laser beams can also be used to
  • the substrates for the gratings are made of special materials.
  • diffraction grating would have a thin layer of epoxy with a thickness
  • Aluminum absorbs more than 1 0% of the
  • An additional layer of a dielectric material might also be
  • Fig. 2 a thin aluminum reflective upper layer (72), an epoxy
  • the thin aluminum layer (72) provides a reflective
  • the laser beam can damage the underlying epoxy layer.
  • discontinuity in the thin aluminum layer allows the laser light to
  • the epoxy substrate needs to be protected from such
  • the overcoat is applied
  • thin aluminum reflective layer and provides a diffraction grating
  • the intense energies of the laser beam are associated with a
  • temperature changes For instance, temperature changes
  • ⁇ represents the wavelength shift
  • ⁇ represents the
  • the photon energy of a laser can be quite high, especially for
  • epoxy substrate is subject to thermal
  • laser is provided for generating a laser output bandwidth of less than
  • the laser resonator preferably includes a laser tube
  • the line-narrowing unit preferably includes a beam
  • expander and a grating may include one or more etalons.
  • grating is preferably a blazed grating having a blaze angle greater
  • the blaze angle is preferably particularly greater than 78°
  • the ornamental design may be between 78° and 82°, and more preferably around 81 °.
  • grating is preferably an echelle type reflection grating, and as such,
  • the line narrowing unit preferably has a diffraction grating
  • preferred grating is defined within the surface of the grating
  • This grating therefore has an
  • this grating is preferably has a coating of reflective dielectric
  • the grating disperses and reflects portions of the incident
  • the outcoupler is preferably a partially transmissive mirror
  • a component such as a polarization component
  • resonator may be a polarization coupled resonator (PCR) .
  • PCR polarization coupled resonator
  • the laser tube includes a discharge chamber filled
  • Fig. 1 A schematically illustrates a broad band laser resonator.
  • Fig. 1 B schematically illustrates a semi-narrow band laser
  • Fig. 2 schematically illustrates a diffraction grating having a
  • Fig. 3A schematically illustrates a laser resonator in accordance with Fig. 3A
  • Fig. 3B schematically illustrates a laser resonator in accordance with Fig. 3B
  • Fig. 4A schematically illustrates a first line-narrowing unit in
  • FIG. 4B schematically illustrates a second line-narrowing unit
  • Fig. 5 schematically illustrates a grating having a blaze angle
  • Figs. 6A-6D schematically illustrate several diffraction gratings
  • Figs. 7A-7B schematically illustrate how to use ion beams to
  • Fig. 8 is a schematic block diagram of a preferred narrow band
  • Fig. 3A schematically illustrates a first laser resonator
  • preionization electrodes (not shown) connected to a discharge circuit
  • the resonator further includes a line-narrowing unit (25), a slit
  • More than one aperture or no aperture may
  • the aperture or apertures may be located in various locations
  • wavelength monitor and stabilization device is included in the laser
  • FIG. 3B schematically illustrates a second resonator
  • Fig. 3B includes a laser tube ( 1 2) and aperture ( 1 9) as described
  • the resonator of Fig. 3B also includes a highly repetitive frequency
  • the resonator of Fig. 3B, and the line-narrowing unit (25) also includes a
  • window of the laser tube or tilted etalon may be used to outcouple
  • Figs. 4A-4B schematically illustrate two preferred line-
  • a prism beam expander one or more etalons and a highly reflective
  • Figs. 4A-4B each have a grating, as shown in Figs. 4A-4B.
  • the line narrowing-unit of Fig. 4A includes a prism beam
  • prism beam expander (32) shown includes two beam expanding
  • the beam expander (32) may comprise a different
  • a beam expanding prisms such as one or more than two.
  • dispersion prism may also be included.
  • expander may be used such as a lens configuration including a
  • the beam expansion prisms may be any suitable beam expansion prisms.
  • each comprise CaF 2 , or fused silica, or the prisms may comprise one
  • each of fused silica and CaF 2 , or the prisms may comprise another
  • wavelengths and repetitions being used (e.g. , 248 nm, 1 93 nm and
  • Preferred beam expanders are set
  • Fig. 4B shows a second preferred line-narrowing unit for use
  • a prism beam expander (32) (as discussed above with respect to Fig. 4A), an etalon (39), a grating (36) and an optional
  • a preferred grating (36) is shown in Fig. 5. This preferred
  • grating may be included in the line narrowing units of each of the
  • Gratings may have grooves on
  • An incident beam l 0 reflects
  • the grating (36) preferably has a line groove
  • the beam l 0 impinges upon the grating (36) and the rays reflect from the grating (36) according to the standard grating
  • the beam is dispersed by the grating (36) such that
  • wavelengths that will be retroreflected back into the laser tube is ⁇ 0 -
  • the wavelength range has a breadth ⁇
  • the angular acceptance range ⁇ 0 is fixed by the resonator and
  • output bandwidth of the laser beam may be adjusted by adjusting
  • ⁇ 0 d ⁇ /d ⁇ « ⁇ ( 1 ), where d ⁇ /d ⁇ is the dispersion of the grating (36).
  • a grating in Littrow configuration (shown schematically in Fig. 4A) is
  • ⁇ ' is the bandwidth
  • ⁇ 0 is the central wavelength of the
  • ⁇ B is the blaze angle of the
  • tan ( ⁇ B ) corresponds to
  • ⁇ " can be adjusted (i.e., reduced) in the following ways:
  • magnification M be maximized in accord with this
  • gas mixture composition should be optimized (particularly the
  • halogen concentration is the gas mixture) as well as the degree of
  • the pulsed discharge mode of the laser has a short lifetime
  • gain medium inversion in the range of ⁇ 1 00 nanoseconds
  • the grating used was an echelle type grating having
  • the preferred slit width of the aperture ( 1 9) is 1 -2 mm.
  • the dose stability has a deviation around ⁇ 3%
  • the second object of the invention is met, i.e., an
  • an optical element such as an etalon outcoupler
  • narrowing unit (25) in accord with the present invention is a
  • the measured bandwidth was around 0.3 pm.
  • the laser beam was less than 2.0 pm.
  • grating (36) is more than 78°, and more preferably the blaze angle of
  • the grating (36) is more than 80°. It is specifically preferred to have
  • the present invention provides a very narrow band excimer
  • the laser system of the present invention is a laser system of high reliability.
  • the laser system of the present invention is a laser system of high reliability.
  • stepper/scanner manufacturers who desire an excimer laser having
  • a preferred grating has a substrate having a surface upon
  • the grating structure is preferably machined or etched directly.
  • the grating surface is preferably coated by a highly UV reflecting
  • reflection enhancing dielectric coating or coating system or an
  • the temperature of the first component Preferably, the temperature of the first component
  • the grating has to be kept constant within the constraints of the
  • a dielectric reflecting layer provides a preferred grating that
  • a substrate may be virtually of any thickness as long as it is
  • the length of the grooves would vary according to or with the grating substrate dimensions (e.g., groove
  • grating substrate would have the dimensions of 30 mm x 1 60 mm x
  • substrate would have dimensions of about about 35 mm x 300 mm
  • the substrate of a preferred diffraction grating is metal, more
  • a preferred grating has a coating combining an aluminum layer
  • Figures 6A-6D show several preferred diffraction gratings.
  • These gratings have a substrate body (80) with a grating structure
  • gratings of Fig. 6 differ from prior art gratings
  • the substrate body (80) of Fig. 6 is
  • the grating surface (92) is coated by a highly UV reflecting dielectric
  • This structure is much more stable against heating and aging
  • Preferred groove distances for diffraction gratings are
  • groove distances correspond to blaze angles between 76° and 82°
  • Fig. 7A shows a way for making a preferred diffraction grating
  • An ion beam (41 ) is used to irradiate the surface of the substrate itself (45) after passing an attenuator (43) providing an
  • the beam cross section is smaller than the substrate surface, the beam
  • FIG. 7B an intermediate diffraction grating replica (47) is
  • a master grating is first formed by etching
  • the master grating may be formed
  • the diffraction grating surfaces of the master may then be treated
  • a release agent such as silicone
  • the release layer is preferably very
  • diffraction grating structure (44) is made of epoxy and the
  • intermediate replica substrate (45) is made of aluminum.
  • the substrate body (45) is variably etched
  • the diffraction grating has a particularly high damage threshold as
  • the diffraction grating is etched directly in the surface material of the
  • substrate which is preferably aluminum.
  • the laser resonator is less than 0.6 pm, and preferably 0.4 pm or less.
  • the line-narrowing unit a line-narrowing unit and an outcoupler.
  • the line-narrowing unit is a line-narrowing unit and an outcoupler.
  • the diffraction grating is
  • invention incorporates a diffraction grating having a diffraction grid
  • the substrate is
  • This grating forms part of a line-narrowing unit
  • the grating is substituted for the highly reflective
  • One or more of the following features contribute to the narrowing of the bandwidth.
  • etalons may also be added for further line narrowing, either just
  • Such lasers generally include
  • a discharge chamber containing two or more gases such as a
  • halogen and one or two rare gases examples include
  • Fig. 8 schematically illustrates a first laser resonator
  • the chamber ( 1 2) contains a pair of main
  • a main discharge gas volume ( 1 3) . It also may contain a
  • the tube includes resonator units in optic modules at each
  • the rear optics module (2) contains a high reflective means (21 ) .
  • rear high reflective means can be a mirror or reflective grating for
  • Wavelength is preferably included with the rear optics module (2) .
  • This substrate is preferably metal, and more preferably,
  • the front optic module (3) contains an outcoupling means (31 )
  • the front optics module (3) preferably contains
  • mirrors such as mirrors, beam splitters, prisms or dispersive elements (e.g.,
  • This substrate is
  • metal preferably metal, and more preferably, aluminum.
  • aluminum preferably aluminum
  • blaze angles are as described above.
  • dispersive gratings are employed
  • Birefringent plates are also used for wavelength selection. See A.
  • solid state laser including a rotatable grating and a fixed beam
  • An electrical pulse power and discharge unit (6) energizes the
  • the pulse power and discharge unit provides
  • a preionization element of the pulse power and discharge unit (not
  • the discharge circuit includes a power supply and pulser
  • circuit for energizing the gas mixture Preferred circuits (not shown)
  • circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and circuit components such as main electrodes ( 1 1 ) and
  • preionization electrodes (not shown) are described at U.S. patent
  • the energy of the output beam ( 1 6) has a known
  • driving energy is preferably adjusted during laser operation to control
  • photodetectors include photodetectors, photodiodes, and pyroelectric detectors.
  • the gas mixture of an excimer or molecular fluorine laser is
  • laser includes an active rare gas such as krypton, argon or xenon, a
  • halogen containing species such as fluorine or hydrogen chloride
  • molecular fluorine includes molecular fluorine and a buffer gas such as neon and/or
  • the gas mixture is naturally heated as it is excited by the
  • the heat exchanger (not limited to
  • supply unit (7) also typically supplies fresh gas to the system from
  • outside gas containers ( 1 7) to replenish each of the components of
  • halogen is typically supplied because
  • cryogenic gas filters see U.S. Patent No. 4,534,034,
  • a processor preferably (9)
  • monitoring discharge chamber gas status e.g.,
  • laser operational status parameters such as a driving voltage meter.
  • the monitor signals and information based upon the history of past

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Lasers (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • General Physics & Mathematics (AREA)

Abstract

L'invention concerne un système laser excimère ou fluor moléculaire générant une largeur de bande de sortie laser inférieure à 0,6 pm, et de préférence à 0,4 pm ou moins. Le résonateur laser est pourvu d'une unité de rétrécissement de ligne comprenant, de préférence, un dilatateur de faisceau et un réseau de diffraction, et peut inclure un ou plusieurs étalons. Le réseau de diffraction est un réseau blazé possédant un angle de blaze supérieur à 76° et, de préférence, supérieur à 80°. La structure de diffraction est, de préférence, définie par la surface du substrat de diffraction. Le substrat est, de préférence, en aluminium. Le coupleur de sortie est, de préférence, un miroir partiellement transmissif positionné sur le côté opposé du tube laser comme l'unité de rétrécissement de ligne. En variante, le couplage de sortie est assuré par un résonateur couplé par polarisation (PCR). Un rotateur de polarisation est, de préférence, utilisé dans cette configuration de résonateur alternative.
PCT/EP2000/011678 1999-11-29 2000-11-23 Laser excimere ou fluor moleculaire a bande tres etroite WO2001041269A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001542432A JP2004503075A (ja) 1999-11-29 2000-11-23 超狭周波数帯エキシマーまたはフッ素分子レーザ

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US16783599P 1999-11-29 1999-11-29
US60/167,835 1999-11-29
US17034299P 1999-12-13 1999-12-13
US60/170,342 1999-12-13
US71236700A 2000-11-14 2000-11-14
US09/712,367 2000-11-14

Publications (1)

Publication Number Publication Date
WO2001041269A1 true WO2001041269A1 (fr) 2001-06-07

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WO (1) WO2001041269A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110187424A (zh) * 2019-05-05 2019-08-30 中国科学院上海光学精密机械研究所 皮米光梳、皮米光梳的制造装置和制造方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016116779A1 (de) * 2016-09-07 2018-03-08 Rofin-Sinar Laser Gmbh Resonatorspiegel für einen optischen Resonator einer Laservorrichtung und Laservorrichtung

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4229710A (en) * 1977-10-21 1980-10-21 Itamar Shoshan Wavelength selector for tunable laser
EP0644462A1 (fr) * 1993-09-20 1995-03-22 Hughes Aircraft Company Usinage par ions réactifs de réseaux et de structures de réseaux croisés
US5852627A (en) * 1997-09-10 1998-12-22 Cymer, Inc. Laser with line narrowing output coupler
US5917849A (en) * 1997-09-10 1999-06-29 Cymer, Inc. Line narrowing device with double duty grating
US5982800A (en) * 1997-04-23 1999-11-09 Cymer, Inc. Narrow band excimer laser
US5982545A (en) * 1997-10-17 1999-11-09 Industrial Technology Research Institute Structure and method for manufacturing surface relief diffractive optical elements

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4229710A (en) * 1977-10-21 1980-10-21 Itamar Shoshan Wavelength selector for tunable laser
EP0644462A1 (fr) * 1993-09-20 1995-03-22 Hughes Aircraft Company Usinage par ions réactifs de réseaux et de structures de réseaux croisés
US5982800A (en) * 1997-04-23 1999-11-09 Cymer, Inc. Narrow band excimer laser
US5852627A (en) * 1997-09-10 1998-12-22 Cymer, Inc. Laser with line narrowing output coupler
US5917849A (en) * 1997-09-10 1999-06-29 Cymer, Inc. Line narrowing device with double duty grating
US5982545A (en) * 1997-10-17 1999-11-09 Industrial Technology Research Institute Structure and method for manufacturing surface relief diffractive optical elements

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110187424A (zh) * 2019-05-05 2019-08-30 中国科学院上海光学精密机械研究所 皮米光梳、皮米光梳的制造装置和制造方法

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