WO2002026003A1 - Method for converting laser radiation into x-radiation, in particular, into extreme ultraviolet (euv) radiation using a plasma generated by the laser radiation - Google Patents

Method for converting laser radiation into x-radiation, in particular, into extreme ultraviolet (euv) radiation using a plasma generated by the laser radiation Download PDF

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Publication number
WO2002026003A1
WO2002026003A1 PCT/DE2001/003635 DE0103635W WO0226003A1 WO 2002026003 A1 WO2002026003 A1 WO 2002026003A1 DE 0103635 W DE0103635 W DE 0103635W WO 0226003 A1 WO0226003 A1 WO 0226003A1
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WO
WIPO (PCT)
Prior art keywords
radiation
euv
laser
plasma
liquid
Prior art date
Application number
PCT/DE2001/003635
Other languages
German (de)
French (fr)
Inventor
Roland Sauerbrey
Thomas Feurer
Original Assignee
Friedrich-Schiller-Universität Jena
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 Friedrich-Schiller-Universität Jena filed Critical Friedrich-Schiller-Universität Jena
Priority to AU2002210368A priority Critical patent/AU2002210368A1/en
Priority to EP01978165A priority patent/EP1410696A1/en
Priority to DE10194039T priority patent/DE10194039D2/en
Publication of WO2002026003A1 publication Critical patent/WO2002026003A1/en

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G2/00—Apparatus or processes specially adapted for producing X-rays, not involving X-ray tubes, e.g. involving generation of a plasma
    • H05G2/001—X-ray radiation generated from plasma
    • 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
    • G03F7/70008—Production of exposure light, i.e. light sources
    • G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources

Definitions

  • the invention relates to a method for converting laser radiation into X-rays, in particular EUV radiation, by means of a plasma generated by the laser radiation.
  • Broadband light sources in the EUV and soft X-ray range can be realized through the interaction of pulsed lasers with matter. If the laser pulses hit solid, liquid or gaseous materials with sufficient intensity, plasmas are generated. These laser-generated plasmas emit both material-characteristic line radiation and material-independent continuum radiation.
  • the plasma parameters - such as scale length, plasma temperature or electron density - determine in which wavelength range the most intense emission occurs. These parameters in turn depend on the characteristic sizes of the laser pulses used.
  • lasers with high peak intensities i.e. with pulse durations of less than about one nanosecond, must be used.
  • the invention is based on the object of increasing the efficiency of the conversion of laser radiation into X-radiation, in particular EUV radiation.
  • amplitude- or phase-modulated sub-nanosecond pulses are irradiated onto the solid, liquid or gaseous material in order to generate a plasma with high radiation conversion efficiency.
  • the energy of the radiation emitted by the plasma is measured in a certain wavelength range by a suitable detector.
  • the amplitude and / or phase structure of the laser pulses for generating the plasma are regulated with regard to a maximum radiation intensity of the X-rays, in particular EUV radiation, so that the energy of the radiation emitted by the laser-generated plasma is also regulated a minimum of laser power for the irradiation of the solid, liquid or gaseous material is obtained.
  • a laser 1 generates pulses 2 in the sub-nanosecond range, which are modulated in their amplitude and / or phase position by a pulse shaper 3.
  • the modulated laser pulses 4 are directed by means of an achromatic corrected lens 5 as focusing optics onto a solid-state target 6 and are brought into interaction with it. This creates a plasma with EUV radiation 7, the intensity of which is measured by an EUV-sensitive detector diode 8 and digitized and fed as feedback signal 9 to a computer 10.
  • the computer 10 changes the type of phase and / or amplitude modulation using a suitable algorithm until the EUV radiation has reached its maximum intensity.
  • the EUV-sensitive detector diode 8 is protected from disruptive laser scatter radiation by a thin aluminum filter 1 1.

Abstract

Broadband light sources in the extreme ultraviolet (EUV) and weak X-ray range can be realized by the interaction of pulsed lasers with matter. Radiation-emitting plasmas are produced when laser pulses impact with a sufficient amount of intensity against solid, liquid or gaseous materials. In order to realize emissions in the hard X-ray range, lasers must be used which have high peak intensities, that is, they have pulse durations of less than one nanosecond. The aim of the invention is to increase the efficiency of the conversion of laser radiation into X-radiation, in particular, into EUV radiation. To this end, the invention provides that amplitude-modulated or phase-modulated sub-nanosecond pulses are irradiated onto the solid, liquid or gaseous material in order to generate a plasma having a high radiation conversion efficiency. The pulse modulation ensues according to the intensity of the X-radiation emitted by the plasma. The invention is used, for example, in electron-beam lithography for producing microelectronic semiconductor components.

Description

Verfahren zur Umwandlung von Laserstrahlung in Röntgenstrahlung, insbesondere EUV-Strahlung, mittels eines von der Laserstrahlung erzeugten PlasmasProcess for converting laser radiation into X-rays, in particular EUV radiation, by means of a plasma generated by the laser radiation
Die Erfindung betrifft ein Verfahren zur Umwandlung von Laserstrahlung in Röntgenstrahlung, insbesondere EUV-Strahlung, mittels eines von der Laserstrahlung erzeugten Plasmas.The invention relates to a method for converting laser radiation into X-rays, in particular EUV radiation, by means of a plasma generated by the laser radiation.
Breitbandige Lichtquellen im EUV und weichen Rontgenbereich lassen sich durch die Wechselwirkung von gepulsten Lasern mit Materie realisieren. Treffen die Laserimpulse mit ausreichender Intensität auf feste, flüssige oder gasförmige Materialien, so entstehen Plasmen. Diese lasererzeugten Plasmen emittieren sowohl materialcharakteristische Linienstrahlung als auch materialunabhängige Kontinuums-Strahlung. Die Plasmaparameter - wie Skalenlänge, Plasmatemperatur oder Elektronendichte - bestimmen, in welchem Wellenlängenbereich die intensivste Emission auftritt. Diese Parameter hängen wiederum von den charakteristischen Größen der verwendeten Laserimpulse ab.Broadband light sources in the EUV and soft X-ray range can be realized through the interaction of pulsed lasers with matter. If the laser pulses hit solid, liquid or gaseous materials with sufficient intensity, plasmas are generated. These laser-generated plasmas emit both material-characteristic line radiation and material-independent continuum radiation. The plasma parameters - such as scale length, plasma temperature or electron density - determine in which wavelength range the most intense emission occurs. These parameters in turn depend on the characteristic sizes of the laser pulses used.
Um Emissionen im harten Rontgenbereich zu realisieren, müssen Laser mit hohen Spitzenintensitäten, also mit Pulsdauern kleiner etwa einer Nanosekunde, verwendet werden.To achieve emissions in the hard X-ray range, lasers with high peak intensities, i.e. with pulse durations of less than about one nanosecond, must be used.
In dem für die Lithographie wichtigen Wellenlängenbereich um 13 nm Wellenlänge kann bisher weniger als ein halbes Prozent der Laserenergie umgewandelt werden. Um dennoch die notwendigen Energien bei 13 nm Wellenlänge zu erzielen wären daher Laser mit heute noch nicht erreichter Ausgangsintensität erforderlich.So far, less than half a percent of the laser energy can be converted in the wavelength range around 13 nm, which is important for lithography. In order to nevertheless achieve the necessary energies at a wavelength of 13 nm, lasers with an output intensity that has not yet been reached would be required.
Es ist auch für spezielle Wellenlängenbereiche vorgeschlagen worden, die Effizienz dieser Energiewandlung durch die Verwendung zweier aufeinanderfolgender Impulse zu erhöhen. Gleichzeitig wurde die Ausbeute weicher Röntgenstrahlung in einem Wellenlängenbereich kleiner 10 nm durch eine automatische Optimierung des zeitlichen Abstandes der beiden Impulse demonstriert.It has also been proposed for special wavelength ranges to increase the efficiency of this energy conversion by using two successive pulses. At the same time, the yield of soft X-rays was all in one Demonstrated wavelength range less than 10 nm by an automatic optimization of the time interval between the two pulses.
Der Erfindung liegt die Aufgabe zu Grunde den Wirkungsgrad der Umwandlung von Laserstrahlung in Röntgenstrahlung, insbesondere EUV-Strahlung, zu erhöhen.The invention is based on the object of increasing the efficiency of the conversion of laser radiation into X-radiation, in particular EUV radiation.
Erfindungsgemäß werden zur Erzeugung eines Plasmas mit hoher Strahlungs- umwandlungseffizienz amplituden- bzw. phasenmodulierte Sub-Nanosekunden- Impulse auf das feste, flüssige oder gasförmige Material eingestrahlt. Die Energie der vom Plasma emittierten Strahlung wird in einem bestimmten Wellenlängenbereich durch einen geeigneten Detektor gemessen. In Abhängigkeit der gemessenen Energie dieser emittierten Strahlung werden die Laserimpulse zur Erzeugung des Plasmas in ihrer Amplituden- und/oder in ihrer Phasenstruktur hinsichtlich einer maximalen Strahlungsintensität der Röntgenstrahlung, insbesondere EUV-Strahlung, geregelt, so dass die Energie der vom lasererzeugten Plasma emittierten Strahlung mit einem Minimum an Laserleistung zur Bestrahlung des festen, flüssigen oder gasförmigen Material gewonnen wird.According to the invention, amplitude- or phase-modulated sub-nanosecond pulses are irradiated onto the solid, liquid or gaseous material in order to generate a plasma with high radiation conversion efficiency. The energy of the radiation emitted by the plasma is measured in a certain wavelength range by a suitable detector. Depending on the measured energy of this emitted radiation, the amplitude and / or phase structure of the laser pulses for generating the plasma are regulated with regard to a maximum radiation intensity of the X-rays, in particular EUV radiation, so that the energy of the radiation emitted by the laser-generated plasma is also regulated a minimum of laser power for the irradiation of the solid, liquid or gaseous material is obtained.
Auf diese Weise wird eine Effizienzsteigerung, speziell im EUV-Bereich, erreicht, die ansonsten nur über eine Erhöhung der primären Laserenergie möglich wäre. Dieses würde aber Energien von Lasern erfordern, die gegenwärtig noch nicht existent sind.In this way, an increase in efficiency, especially in the EUV area, is achieved that would otherwise only be possible by increasing the primary laser energy. However, this would require energies from lasers that currently do not yet exist.
Die Erfindung soll nachstehend anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert werden.The invention will be explained below with reference to an embodiment shown in the drawing.
In der Figur ist die erfindungsgemäße Vorrichtung in ihrem Prinzipaufbau dargestellt.The basic structure of the device according to the invention is shown in the figure.
Ein Laser 1 erzeugt Impulse 2 im Sub-Nanosekunden-Bereich, welche durch einen Pulsformer 3 in ihrer Amplitude und/oder Phasenlage moduliert werden. Die modulierten Laserimpulse 4 werden mittels einer achromatischen korrigierten Linse 5 als Fokussieroptik auf ein Festkörpertarget 6 gelenkt und mit dieser zur Wechselwirkung gebracht. Dabei entsteht ein Plasma mit einer EUV-Strahlung 7, deren Intensität durch eine EUV-empfindliche Detektordiode 8 gemessen und digitalisiert als Rückkopplungssignal 9 zu einem Rechner 10 geleitet wird.A laser 1 generates pulses 2 in the sub-nanosecond range, which are modulated in their amplitude and / or phase position by a pulse shaper 3. The modulated laser pulses 4 are directed by means of an achromatic corrected lens 5 as focusing optics onto a solid-state target 6 and are brought into interaction with it. This creates a plasma with EUV radiation 7, the intensity of which is measured by an EUV-sensitive detector diode 8 and digitized and fed as feedback signal 9 to a computer 10.
Der Rechner 10 verändert über einen geeigneten Algorithmus die Art der Phasen- und/oder Amplituden-Modulation bis die EUV-Strahlung ihre maximale Intensität erreicht hat.The computer 10 changes the type of phase and / or amplitude modulation using a suitable algorithm until the EUV radiation has reached its maximum intensity.
Die EUV-empfindliche Detektordiode 8 wird durch einen dünnen Aluminiumfilter 1 1 vor störender Laserstreustrahlung geschützt. The EUV-sensitive detector diode 8 is protected from disruptive laser scatter radiation by a thin aluminum filter 1 1.
Aufstellung der verwendeten BezugszeichenList of the reference symbols used
1 - Laser1 - laser
2 - Impulse2 - pulses
3 - Pulsformer3 - pulse shaper
4 - modulierte Laserpulse4 - modulated laser pulses
5 - Linse5 - lens
6 - festes, flüssiges oder gasförmiges Material6 - solid, liquid or gaseous material
7 - zu erzeugende Strahlung7 - radiation to be generated
8 - Detektordiode8 - detector diode
9 - Rückkopplungssignal9 - feedback signal
10 - Rechner10 - calculator
1 1 - Aluminiumfilter 1 1 - aluminum filter

Claims

Patentanspruchclaim
Verfahren zur Umwandlung von Laserstrahlung in Röntgenstrahlung, insbesondere EUV-Strahlung, mittels eines durch Bestrahlung eines festen, flüssigen oder gasförmigen Material von der Laserstrahlung erzeugten Plasmas, bei dem die Laserstrahlung in Abhängigkeit der vom Plasma emittierten Röntgenstrahlung beeinf lusst wird, dadurch gekennzeichnet, dass für die Erzeugung eines Plasmas hoher Strahlungsumwandlungseffizienz das feste, flüssige oder gasförmige Material mit in Abhängigkeit von der Intensität der emittierten Röntgenstrahlung amplituden- und/oder phasenmodulierten Sub- Nanosekunden-Impulsen bestrahlt wird. Method for converting laser radiation into X-rays, in particular EUV radiation, by means of a plasma generated by the irradiation of a solid, liquid or gaseous material, in which the laser radiation is influenced as a function of the X-rays emitted by the plasma, characterized in that for the generation of a plasma of high radiation conversion efficiency, the solid, liquid or gaseous material is irradiated with amplitude-modulated and / or phase-modulated sub-nanosecond pulses depending on the intensity of the emitted X-rays.
PCT/DE2001/003635 2000-09-20 2001-09-19 Method for converting laser radiation into x-radiation, in particular, into extreme ultraviolet (euv) radiation using a plasma generated by the laser radiation WO2002026003A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU2002210368A AU2002210368A1 (en) 2000-09-20 2001-09-19 Method for converting laser radiation into x-radiation, in particular, into extreme ultraviolet (euv) radiation using plasma generated by the laser radiation
EP01978165A EP1410696A1 (en) 2000-09-20 2001-09-19 Method for converting laser radiation into x-radiation, in particular, into extreme ultraviolet (euv) radiation using a plasma generated by the laser radiation
DE10194039T DE10194039D2 (en) 2000-09-20 2001-09-19 Process for converting laser radiation into X-rays, in particular EUV radiation, by means of a plasma generated by the laser radiation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2000147779 DE10047779A1 (en) 2000-09-20 2000-09-20 Method for converting laser beams into X-rays like EUV rays uses amplitude/phase-modulated sub-nanosecond impulses to create plasma that has high radiation conversion efficiency and is generated by the laser beams.
DE10047779.8 2000-09-20

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WO2002026003A1 true WO2002026003A1 (en) 2002-03-28

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EP (1) EP1410696A1 (en)
AU (1) AU2002210368A1 (en)
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4058486A (en) * 1972-12-29 1977-11-15 Battelle Memorial Institute Producing X-rays

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4058486A (en) * 1972-12-29 1977-11-15 Battelle Memorial Institute Producing X-rays

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
BEHJAT A ET AL: "The effects of multi-pulse irradiation on X-ray laser media", OPTICS COMMUNICATIONS, NORTH-HOLLAND PUBLISHING CO. AMSTERDAM, NL, vol. 135, no. 1, 1 February 1997 (1997-02-01), pages 49 - 54, XP004016375, ISSN: 0030-4018 *

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AU2002210368A1 (en) 2002-04-02
EP1410696A1 (en) 2004-04-21
DE10194039D2 (en) 2003-09-11
DE10047779A1 (en) 2002-03-28

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