WO2000019496A1 - Laser plasma x-ray generator, semiconductor aligner having the generator, and semiconductor exposure method - Google Patents

Laser plasma x-ray generator, semiconductor aligner having the generator, and semiconductor exposure method Download PDF

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Publication number
WO2000019496A1
WO2000019496A1 PCT/JP1998/004338 JP9804338W WO0019496A1 WO 2000019496 A1 WO2000019496 A1 WO 2000019496A1 JP 9804338 W JP9804338 W JP 9804338W WO 0019496 A1 WO0019496 A1 WO 0019496A1
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WO
WIPO (PCT)
Prior art keywords
metal oxide
laser
plasma
ray generator
target
Prior art date
Application number
PCT/JP1998/004338
Other languages
French (fr)
Japanese (ja)
Inventor
Tetsuya Matsui
Nobuyoshi Kogawa
Original Assignee
Hitachi, Ltd.
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Publication date
Application filed by Hitachi, Ltd. filed Critical Hitachi, Ltd.
Priority to PCT/JP1998/004338 priority Critical patent/WO2000019496A1/en
Publication of WO2000019496A1 publication Critical patent/WO2000019496A1/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
    • 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
    • G03F7/70008—Production of exposure light, i.e. light sources
    • G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources
    • 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
    • G03F7/70908—Hygiene, e.g. preventing apparatus pollution, mitigating effect of pollution or removing pollutants from apparatus
    • G03F7/70916—Pollution mitigation, i.e. mitigating effect of contamination or debris, e.g. foil traps
    • 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
    • G21K5/00—Irradiation devices
    • G21K5/04—Irradiation devices with beam-forming means

Definitions

  • the present invention relates to a laser plasma X-ray generator that irradiates a target with laser light to generate plasma and generates X-rays from the plasma, a semiconductor exposure apparatus using the laser plasma X-ray generator, and Related to semiconductor exposure method. Background art
  • an electron beam irradiation type X-ray generator and a laser plasma X-ray generator are known.
  • the X-ray emission mechanism of the electron beam irradiation type X-ray generator is that when one irradiated electron flicks one inner shell electron of the target element, the inner shell electrons transition and emit X-rays.
  • Such an electron beam irradiation type X-ray generator having an X-ray wavelength band of several keV to several MeV is disclosed in JP-A-58-204451 and JP-A-2-267843. Published in Kaihei 2—309597.
  • the target is turned into a plasma by the laser (a large number of electrons are blown off), and multiply-charged ions are formed, which are recombined with the electrons.
  • X-rays are emitted during the process, and the X-ray wavelength band ranges from several OeV to several keV. Comparing these X-rays from the electron beam irradiation type X-ray generator with the X-rays from the laser plasma x-ray generator, the X-ray brightness is lower for the X-rays from the electron beam irradiation type X-ray generator. High for X-rays from a laser plasma X-ray generator. X-ray intensity of the X-rays from the laser plasma X-ray generating apparatus ing to 1 0 8 times the peak value for the luminance of the X-rays from the electron beam irradiation morphism X-ray generator. -In semiconductor exposure equipment, higher X-ray brightness is advantageous from the viewpoint of shortening the exposure time and preventing the occurrence of underexposure.
  • JP-A-6-281799 describes that X-rays are generated by irradiating a tape-shaped solid target to be wound with a laser beam.
  • JP-A-61-153935 describes that X-rays are generated by irradiating a dropped liquid metal with a laser beam.
  • Japanese Patent Application Laid-Open No. 2-1100297 describes that a bullet-shaped target having a small spot of laser light is irradiated with laser light to generate X-rays.
  • Japanese Patent Application No. 57-41167 describes that X-rays are generated by irradiating solidified rare gas or water particles with laser light.
  • No. 5577092 injects pressurized gas into a vacuum vessel, forms clusters in the injected gas, and irradiates it with laser light to generate X-rays. It is described.
  • JP-A-10-31099 describes that X-rays are generated using a target in which metal fine particles are scattered in a transparent substrate.
  • atoms and molecules in the target are optically broken down (optically broken down), ionized, and laser plasma is generated.
  • X-rays are generated from the generated laser plasma.
  • the laser beam intensity required for optical breakdown differs depending on the type and state of the target element.
  • Electron temperature and density of the laser plasma, the type of elements contained in the target, and varies the laser type and conditions, the number 1 0 0 e V or more electron temperature, 1 in the electron density 0 2 ° ⁇ 1 0 2 Plasma of about 2 / cm 3 is generated.
  • the X-rays generated are continuous spectra from the laser plasma due to the bremsstrahlung radiation of the electrons in the laser plasma, the free-free transition and the free-bundle transition in the plasma recombination process. X-rays are emitted, and characteristic X-rays are emitted by the process of bound-to-bound transition in the plasma recombination process.
  • the X-ray spectrum obtained at this time depends on the type of elements contained in the target, the electron temperature and the density of the laser plasma, and the like.
  • a semiconductor device exposing device that generates X-rays from a laser plasma and guides the generated X-rays to a semiconductor wafer to expose a semiconductor device pattern onto a semiconductor wafer includes an optical element that condenses the generated X-rays.
  • a multilayer mirror is used, but the wavelength band that can be reflected by this mirror is extremely limited.
  • Fig. 2 shows an example of the wavelength dependence of the reflectance in the case of a MoZSi multilayer mirror.
  • the band width of the wavelength band that can be reflected as shown here is 0.4 to 0.4. It has an extremely narrow wavelength width of 6 nm.
  • the X-rays generated from the laser plasma also have a high X-ray intensity in the wavelength band of such a mirror.
  • the essential condition of a laser plasma X-ray generator is that the X-ray conversion rate obtained when the laser beam intensity is used as the denominator and the X-ray intensity in the usable wavelength band is used as the numerator is high. .
  • the solid and liquid targets are made into particles with small laser diameters, debris is reduced because there are no particles around, and the X-ray conversion efficiency is the same as that of solids and liquids. It is difficult to stably supply each of them at the same time as the irradiation of laser light, and it is also difficult to stably generate X-rays.
  • the target of particles formed by freezing a chemically stable gas such as a rare gas does not generate debris because it becomes a chemically stable gas such as a rare gas even when it is melted. It is difficult to generate stable X-rays. X-ray conversion efficiency is lower than that of metal targets.
  • first object of the present invention is to provide a laser plasma X-ray generator having high X-ray conversion efficiency and low debris generation
  • a second object is to provide a laser plasma X-ray generator.
  • a third object of the present invention is to provide a semiconductor exposure method using the laser plasma X-ray generator.
  • a feature of the laser plasma X-ray generator of the present invention is that a metal oxide is a target. According to this feature, a high X-ray conversion rate unique to metal oxides can be obtained, and since the melting point of metal oxides is generally higher than that of metal alone, they are less likely to melt and generate debris. It can be reduced.
  • Another feature of the laser plasma X-ray generator according to the present invention is that the metal oxide is made into fine particles and the diameter of the metal oxide fine particles is made smaller than that of the laser beam irradiated to the target. . According to this feature, since more particles are present in the plasmatable region, the plasma can be reliably formed, and the heat conduction between the metal oxide fine particles is small. Since debris does not occur, the generation of debris can be further reduced.
  • Another feature of the laser plasma X-ray generator of the present invention resides in that metal oxide fine particles are injected together with gas into a laser beam irradiation section. According to this feature, the target in which the particles and the gas are mixed is ejected to become a fluid, and the target is always supplied to the laser pulse, so that the X-ray can be stably provided. Can be generated.
  • Another feature of the laser plasma X-ray generator of the present invention resides in that the fine particles or gas supplied as described above are recovered and supplied again. -According to this feature, since the fine particles or gas can be reused, the operating cost can be reduced.
  • the metal oxide is a solid or a sintered body, which is made into a rod shape, and is continuously fed from outside to inside the vacuum vessel. And to continuously extract the laser-irradiated part from the inside of the vacuum vessel to the outside.
  • a solid or sintered metal oxide can be continuously supplied and a laser plasma X-ray generator having a high X-ray conversion rate can be configured.
  • Another feature of the laser plasma X-ray generator of the present invention resides in that the metal oxide is in a powder form, and is applied to a tape-shaped substrate for use. At this time, it is necessary to have a device for applying powdered metal oxide to the tape-shaped substrate and a device for continuously supplying the tape coated with the metal oxide to the laser irradiation unit. It is in. According to this feature, a metal oxide can be continuously supplied, and a laser plasma X-ray generator having a high X-ray conversion rate can be configured.
  • the laser plasma X-ray generator of the present invention targeting a metal oxide is used to generate X-rays generated from the laser plasma X-ray generator.
  • the focusing mirror guides the light to the mask, and the X-ray reduction exposure mirror reduces the X-rays reflected by the mask and projects the reduced X-rays on the semiconductor wafer.
  • the generation of debris is small in the laser plasma X-ray generator, damage to the X-ray optical elements such as the condensing mirror, mask, X-ray reduction exposure mirror, etc. of the semiconductor exposure apparatus and the vacuum partition is prevented. Can be passed.
  • the exposure time does not become insufficient and the exposure time can be shortened.
  • FIG. 1 is an overall view of a semiconductor exposure apparatus using a laser plasma X-ray generator according to a first embodiment of the present invention.
  • FIG. 2 is a graph showing the wavelength dependence of the X-ray reflectivity in the case of a MoZSi multilayer mirror.
  • FIG. 3 is a graph showing an X-ray spectrum obtained by the laser plasma X-ray generation apparatus employed in the first embodiment of the present invention.
  • FIG. 4 is an overall view of a semiconductor exposure apparatus using a laser plasma X-ray generator according to a second embodiment of the present invention.
  • FIG. 5 is an overall view of a laser plasma X-ray generator according to a third embodiment of the present invention.
  • FIG. 6 is a graph showing an X-ray spectrum of X-rays obtained by a laser plasma X-ray generator according to a third embodiment of the present invention.
  • FIG. 7 is an overall view of a laser plasma X-ray generator according to a fourth embodiment of the present invention.
  • the inventors irradiate various targets with a laser and measure X-rays from laser plasma. As a result, they have found that metal oxides have a higher X-ray conversion rate than metal alone or gas alone.
  • FIG. 1 shows a semiconductor exposure apparatus using a laser plasma X-ray generator according to a first embodiment of the present invention.
  • the semiconductor exposure apparatus includes an X-ray generation unit 100, which is a laser plasma X-ray generation device that generates X-rays, and an exposure unit 200.
  • the exposure unit 200 guides the X-rays 14 generated by the X-ray generation unit 100 to the mask 16 by the X-ray focusing mirror 15 and reduces the mask pattern reflected by the mask 16 to X-ray exposure. It is reduced by the mirror 17 and projected onto the wafer 18 (sample).
  • Figure 2 shows an example of the reflectivity of the multilayer mirror used in the X-ray focusing mirror 15, the mask 16, and the X-ray reduction exposure mirror 17.
  • the band width of the wavelength band that can be reflected is an extremely narrow wavelength width of 0.4 nm
  • the center wavelength is the center wavelength in the case of this MoZSi multilayer mirror.
  • the wavelength is 13.7 nm.
  • the X-ray generator 100 which is a laser plasma X-ray generator, will be described in detail.
  • the X-ray generator 100 includes a vacuum vessel 5 surrounding the target, a target supply device 110 for supplying the mixed gas of fine particles into the vacuum vessel 5 as a target, It comprises a laser irradiation device 120 for irradiating the target 10 with the laser beam 2, and a target collection device 130 for collecting the mixed gas of fine particles in the vacuum vessel 5.
  • the target supply device 110 includes a fine particle tank 6 filled with metal oxide fine particles having a small laser focusing diameter, a gas cylinder 7 filled with gas, and a metal oxide fine particle supplied from the fine particle tank 6. And a mixer 8 for mixing a rare gas supplied from a gas cylinder 7 and a supply nozzle 9 for injecting a mixed gas of fine particles produced by the mixer 8 into a vacuum vessel 5.
  • a mixer 8 for mixing a rare gas supplied from a gas cylinder 7 and a supply nozzle 9 for injecting a mixed gas of fine particles produced by the mixer 8 into a vacuum vessel 5.
  • metal oxide fine particles were obtained only with the fine particle tank 6 and the supply nozzle 9. You may supply them.
  • the metal oxide fine particles used are Cr, Mn, Co, Ni, CuSr, Y, Zr, Nb, Mo, Ag, In, Sn, Sb. , Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Ta, W, Pb. Yes, it has an X-ray peak suitable for the reflection wavelength band of the multilayer mirror of the X-ray focusing mirror 15, mask 16,-and X-ray reduction exposure mirror 17 used in the exposure unit 200 Try to select one.
  • the laser irradiation device 120 includes a laser light generator 1 that generates the laser light 2 and a converging lens 3 that converges the laser light 2.
  • the laser light generator 1 generates a laser beam 2 such as a YAG laser or an excimer laser with a pulse width of several 10 ns or less and an output per pulse of several 10 mJ to several 10 J. Is good.
  • the laser beam 2 is converged by the converging lens 3 on the fine particle mixed gas target in the vacuum vessel 5 so that the diameter becomes several 10 to several 100 ⁇ m.
  • the energy density on the gaseous particle-mixed target 10 should be about 10 15 to 10 22 W m 2 .
  • the target recovery device 130 is provided with a recovery duct 12 and a recovery device 13 which are supplied into the vacuum vessel 5 and draw metal oxide fine particles and gas which have not been turned into plasma or returned to a steady state. Prepare.
  • the injection port of the supply nozzle 9 and the recovery port of the recovery duct 12 are disposed so as to face each other.
  • the laser light 2 from the laser irradiation device 120 passes through the laser light transmission window 4 provided on the wall surface of the vacuum vessel 5 and irradiates the fine particle mixed gas 10 injected from the supply nozzle 9.
  • the inside of the vacuum container 5 is maintained at a low pressure by a vacuum pump (not shown).
  • a vacuum pump not shown.
  • An example Example the pressure in the vacuum vessel 5 and below 1 0 _ 2-to rr, if the pressure in the supply Roh nozzle 9 to several atmospheres, particulate mixture gas 1 0, that Do the state of fluid ejected . Then, the particulate mixed gas 10 that has not been turned into plasma or has returned to the steady state enters the recovery duct 12 and is removed from the vacuum vessel 5.
  • the metal oxide and gas in the particulate mixed gas target 10 are optically dielectrically broken by the strong electric field of the laser beam 2 and the like. (Optical breakdown) to ionize.
  • the electrons generated by the ionization absorb the energy of the laser beam 2 through processes such as reverse braking radiation and are heated, so that the high-temperature and high-density areas are within a range where the laser beam 2 of the gas target 10 is mixed.
  • a laser plasma 11 is formed.
  • the electron temperature and density of the laser plasma 11 vary depending on the type of metal oxide and gas contained in the particulate mixed gas target 10 and the type and conditions of the laser. 1 in the electron density 0 2 ° ⁇ 1 0 may 2 2 / cm 3 about the plasma is generated.
  • Laser plasma 11 Due to the bremsstrahlung emission of electrons in the plasma, free-free transition and free-bundle-transition process in the plasma recombination process,
  • X-rays of a continuous spectrum are emitted from 11 and characteristic X-rays are emitted due to the bound-to-bound transition in the plasma recombination process.
  • X-rays emitted from the laser plasma 11 are used in the adjacent exposure unit 200.
  • FIG. 3 shows the X-ray spectrum obtained by the present embodiment.
  • S n 0 2 fine particles particle size: about 1 0 nm
  • a r gas cylinder gas pressure: 7 atm
  • There laser light output: 700 mJ // pulse, pulse width: 5 ns
  • (Wavelength: 1064 nm) was condensed by a lens (focal length: 200 mm) and irradiated.
  • a rare gas X e, K r
  • 0 2 gas has a peak of several going between 1 0 to 1 3 nm, as shown in FIG. 3, on the other hand, S n itself is subjected to 1 3 ⁇ 1 6 nm as shown in FIG. 6 Has a broad peak.
  • the X-ray conversion efficiency in the reflection wavelength band of the multilayer mirror is higher than that of the rare gas target. high.
  • the metal oxide fine particle mixed gas target has a low thermal conductivity of the metal oxide and a very low heat conduction to the metal oxide fine particles other than the laser irradiated part, so that the metal oxide other than the laser irradiated part is not oxidized. Debris can be reduced because the material particles do not melt.
  • a target in which metal oxide fine particles and a gas are mixed is injected into the vacuum container 5, and a laser beam is applied to the target that has been injected and becomes a fluid. Since irradiation is performed, the target is always supplied to the laser pulse, so that X-rays can be generated stably.
  • the inside of the vacuum container 5 can be kept at a low pressure, and absorption loss of generated X-rays can be prevented.
  • a second embodiment of the present invention will be described with reference to FIG.
  • a separator 30 for separating metal oxide fine particles and gas is provided in the target collector 13 in the first embodiment, and the gas collected from the target collected in the collector 13
  • the metal oxide fine particles are separated and recovered by a separator 30, and the separated metal oxide fine particles are returned to the original fine particle tank 6 and the separated gas is returned to the gas cylinder 7 for recycling. It was done.
  • Other contents are the same as those of the first embodiment of the present invention.
  • a third embodiment of the present invention will be described with reference to FIG.
  • a solid or sintered metal oxide is used as a target.
  • a solid or sintered body of metal oxide is continuously inserted into a vacuum vessel 5 by a rod inserter 24 as a rod-shaped target 23. Then, the rod-shaped target 23 irradiated with the laser is taken out of the vacuum vessel.
  • Figure 6 shows the X-ray spectrum obtained when the metal oxide was used as a solid or sintered body.
  • S n 0 2 solid as the metal oxide
  • there laser beam output: 7 0 0 m J // pulse, pulse width: 5 ns, wavelength: 1 0 6 4 nm
  • Focus with a lens (focal length: 200 mm) Irradiated.
  • the spectra for simple metals Sn, Au, Ni
  • Ni Let 's can be seen from this figure, the S n 0 2 solid, whereas strong peak around the 1 3. 7 nm as in the case of FIG. 3 is one, with only simple metal, the X-ray intensity You can see that it is weak.
  • the X-rays thus obtained are introduced into the exposure unit 200 of the first embodiment of the present invention, and a mask pattern is formed on a semiconductor wafer 18 similarly to the first embodiment of the present invention. Used for projection
  • the metal oxide fine particles used here are Cr, Mn, Co, Ni, Cu, Sr, Y, Zr, and Nr. b, Mo, Ag, In, Sn, Sb, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Ta, It is an oxide of one or more of the metals W and Pb, and is an X-ray focusing mirror 15, mask 16 and X-ray reduction exposure mirror 17 used in the exposure unit 200. The one that has an X-ray peak suitable for the reflection wavelength band of the multilayer mirror is selected. Other details are the same as in the first embodiment of the present invention.
  • the metal oxide solid is used, so that the X-ray conversion efficiency in the reflection wavelength band of the multilayer mirror is higher than that of the metal single target. Since the metal oxide solid has a low thermal conductivity, the metal oxide solid is less likely to melt the metal fine particles other than the laser irradiating portion, thereby reducing debris.
  • a metal oxide is made into a powdery form and applied to a tape-shaped substrate.
  • a powdery metal oxide is applied to the surface of the tape-like target 25 by a metal oxide applying device 28.
  • the method of application is to disperse the powdered metal oxide in a solvent and then apply it by spraying, or to disperse the powdered metal oxide in the solvent and then use the tape-like target 25 in the solvent.
  • a method of dipping and applying is applicable.
  • a drying means may be incorporated in the metal oxide coating device 28.
  • the tape-like target 25 coated with the powdered metal oxide is supplied by a tape-like target supply / reproduction system 140 composed of a tape inserter 26 and a roll 27. It is supplied to the laser irradiating unit, and after the laser irradiation, is re-coated by the metal oxide coating device 28 and is used continuously.
  • Resulting X-ray spectrum is Ri similar der to FIG. 6, in the case of using a M o ZS i multilayer Makumi error, in S n 0 2 solid, S n, A u, F e, of the N i single metal More than three times the X-ray conversion rate can be obtained.
  • the X-rays thus obtained are introduced into the exposure unit 200 of the first embodiment of the present invention, and a mask pattern on a semiconductor wafer 18 is formed in the same manner as in the first embodiment of the present invention. Used to project
  • the metal oxide fine particles used here are Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Nb, o, Ag, Any one of In, Sn, Sb, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Ta, W, and Pb. It is an oxide of one or more metals, and has a reflection wavelength band of the multilayer mirror of the X-ray focusing mirror 15, mask 16, and X-ray reduction exposure mirror 17 used in the exposure unit 200. Try to select one with a suitable X-ray peak. Other details are the same as in the first embodiment of the present invention. According to this embodiment, the following effects can be obtained. In this embodiment, the use of the tape-shaped target coated with the metal oxide powder on the surface makes the X-ray conversion efficiency in the reflection wavelength band of the multilayer mirror higher than that of the single metal target. high.
  • the metal oxide powder itself has low heat conduction, the metal oxide powder has little melting of metal fine particles other than the laser irradiating portion, and can reduce debris.
  • the X-ray conversion efficiency in the reflected wavelength band of a multilayer mirror used in an exposure unit has been known. It is higher than the target of rare gas or metal alone.
  • the metal oxide has low heat conduction, and the metal oxide is hardly melted in portions other than the laser irradiated portion, so that debris can be reduced.

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Abstract

A laser plasma X-ray generator which has a high X-ray conversion efficiency and produces little debris, a semiconductor aligner using the generator and a semiconductor exposure method are disclosed. In the laser plasma X-ray generator, the target to be irradiated with a laser beam is a metal oxide. The semiconductor aligner comprising such a laser plasma X-ray generator is characterized by further comprising a collecting mirror which directs X-rays generated by the plasma X-ray generator to a mask, and an X-ray convergence exposure mirror which converges the X-rays reflected by the mask and projects the X-rays onto a semiconductor wafer. In the semiconductor exposure method, X-rays generated by a laser plasma X-ray generator where the target is a metal oxide are collected, applied to a mask, and reflected by the mask, the reflected X-rays are converged, and a semiconductor mask pattern is projected onto a semiconductor wafer to expose it.

Description

明 細 書  Specification
レーザプラズマ X線発生装置およびそれを用  Laser plasma X-ray generator and its use
いた半導体露光装置並びに半導体露光方法  Semiconductor exposure apparatus and semiconductor exposure method
技術分野 Technical field
本発明は、 レーザ光をターゲッ -卜に照射してプラズマを生成し、 その プラズマから X線を発生させるレーザプラズマ X線発生装置と、 そのレ 一ザプラズマ X線発生装置を用いた半導体露光装置並びに半導体露光方 法に関する。 背景技術  The present invention relates to a laser plasma X-ray generator that irradiates a target with laser light to generate plasma and generates X-rays from the plasma, a semiconductor exposure apparatus using the laser plasma X-ray generator, and Related to semiconductor exposure method. Background art
半導体露光装置では、 X線発生装置から発生した X線を集光してマス クに当てて反射させ、 その反射 X線を縮小して半導体のマスクパターン を半導体ウェハに投影する半導体露光方法が実施されている。  In semiconductor exposure equipment, a semiconductor exposure method that focuses X-rays generated by an X-ray generator, impinges it on a mask and reflects it, reduces the reflected X-rays, and projects a semiconductor mask pattern onto a semiconductor wafer has been implemented. Have been.
X線発生装置には、 電子線照射型 X線発生装置と レーザプラズマ X線 発生装置とが知られている。  As the X-ray generator, an electron beam irradiation type X-ray generator and a laser plasma X-ray generator are known.
電子線照射型 X線発生装置の X線放出メカニズムは、 一個の照射電子 がターゲッ ト元素の内殻電子 1個を弾き飛ばした際に内殻電子が遷移し X線を放出するという もので、 X線波長帯が数 k e V〜数 M e Vである , このよ う な、 電子線照射型 X線発生装置,は、 特開昭 58— 204451号公報 ゃ特開平 2— 267843号公報ゃ特開平 2— 309597号公報に掲載されている。 一方、 レーザプラズマ X線発生装置の X線放出メカニズムは、 レーザ によ り ターゲッ トがブラズマ化され （多数の電子が弾き飛ばされ、 ） 、 多価イオンが形成されて、 それが電子と再結合する過程で X線を放出す るという もので、 X線波長帯が数 1 O e V〜数 k e Vである。 これら、 電子線照射型 X線発生装置からの X線と レーザプラズマ x線 発生装置からの X線と を比較すると、 X線の輝度が電子線照射型 X線発 生装置からの X線では低く 、 レーザプラズマ X線発生装置からの X線で は高い。 レーザプラズマ X線発生装置からの X線の X線輝度は電子線照 射型 X線発生装置からの X線の輝度に対してピーク値で 1 0 8 倍にもな る。 - 半導体露光装置では、 露光時間を短く する事や、 露光不足が発生しな い様にするという観点で、 X線の輝度が高い方が有利である。 The X-ray emission mechanism of the electron beam irradiation type X-ray generator is that when one irradiated electron flicks one inner shell electron of the target element, the inner shell electrons transition and emit X-rays. Such an electron beam irradiation type X-ray generator having an X-ray wavelength band of several keV to several MeV is disclosed in JP-A-58-204451 and JP-A-2-267843. Published in Kaihei 2—309597. On the other hand, in the X-ray emission mechanism of the laser plasma X-ray generator, the target is turned into a plasma by the laser (a large number of electrons are blown off), and multiply-charged ions are formed, which are recombined with the electrons. X-rays are emitted during the process, and the X-ray wavelength band ranges from several OeV to several keV. Comparing these X-rays from the electron beam irradiation type X-ray generator with the X-rays from the laser plasma x-ray generator, the X-ray brightness is lower for the X-rays from the electron beam irradiation type X-ray generator. High for X-rays from a laser plasma X-ray generator. X-ray intensity of the X-rays from the laser plasma X-ray generating apparatus ing to 1 0 8 times the peak value for the luminance of the X-rays from the electron beam irradiation morphism X-ray generator. -In semiconductor exposure equipment, higher X-ray brightness is advantageous from the viewpoint of shortening the exposure time and preventing the occurrence of underexposure.
そのために、 電子線照射型 X線発生装置からの X線よ り も、 レーザプ ラズマ X線発生装置からの X線を用いる事が半導体露光の技術分野では 有利である。  For this reason, it is more advantageous in the semiconductor exposure technical field to use X-rays from a laser plasma X-ray generator than X-rays from an electron beam irradiation type X-ray generator.
レーザプラズマ X線発生装置を開示する従来例と しては、 以下のもの が存在する。  The following are examples of conventional examples that disclose a laser plasma X-ray generator.
特開平 6— 281 799 号公報は、 巻き取り されるテープ状の固体ターゲッ トにレーザ光を照射して X線を発生させる こと を記載する。  JP-A-6-281799 describes that X-rays are generated by irradiating a tape-shaped solid target to be wound with a laser beam.
特開昭 61— 153935号公報は、 滴下された液体金属にレーザ光を照射し て X線を発生させる ことを記載する。  JP-A-61-153935 describes that X-rays are generated by irradiating a dropped liquid metal with a laser beam.
特開平 2— 1 00297 号公報は、 レーザ光のスポッ ト径ょ り も小さいビュ レ ツ ト状のタ一ゲッ 卜にレーザ光を照射して X線を発生させること を記 載する。  Japanese Patent Application Laid-Open No. 2-1100297 describes that a bullet-shaped target having a small spot of laser light is irradiated with laser light to generate X-rays.
特願昭 57— 41 167号公報は、 固体化された希ガスや水の粒子にレーザ 光を照射して X線を発生させる ことを記載する。  Japanese Patent Application No. 57-41167 describes that X-rays are generated by irradiating solidified rare gas or water particles with laser light.
Un i t ed S ta le s Pa te nt No . 5577092は、 真空容器中に加圧ガスを噴射 し、 噴射されたガス中でクラスターを形成させ、 そこにレーザ光を照射 して X線を発生させること を記載する。 特開平 10— 31099 号公報は、 金属微粒子を透明基板中に散在させたタ ーゲッ トを用いて X線を発生させる ことを記載する。 No. 5577092 injects pressurized gas into a vacuum vessel, forms clusters in the injected gas, and irradiates it with laser light to generate X-rays. It is described. JP-A-10-31099 describes that X-rays are generated using a target in which metal fine particles are scattered in a transparent substrate.
レーザ光をターゲッ トに照射して X線を発生させる技術や、 X線を利 用する半導体露光装置では次のよう な課題が存在している。  The following issues exist in the technology that generates X-rays by irradiating a target with laser light and in semiconductor exposure equipment that uses X-rays.
レーザ光がターゲッ トに照射されると、 タ一ゲッ ト中の原子や分子は 光学的に絶縁破壊 （ォプティ カル-ブレイ クダウン） してイオン化し、 レ 一ザプラズマが発生する。 発生したレーザプラズマから X線が発生する ターゲッ トの元素の種類や状態によって、 オプティ カルブレイクダウン に必要なレーザ光強度は異なる。 レーザプラズマの電子温度や密度は、 ターゲッ トに含まれる元素の種類、 およびレーザの種類や条件によって 異なるが、 電子温度で数 1 0 0 e V以上、 電子密度で 1 0 2 ° ~ 1 0 2 2 / cm3 程度のプラズマが発生する。 発生する X線と しては、 レーザプラズ マ中の電子の制動輻射、 プラズマの再結合過程における自由一自由遷移 や自由一束縳遷移の過程によ り 、 レーザプラズマから連続的なスぺク ト ルの X線が放出され、 ま た、 プラズマの再結合過程における束縛一束縛 遷移の過程によ り 、 特性 X線が放出される。 このと き得られる X線のス ベク トルは、 ターゲッ トに含まれる元素の種類や、 レ一ザプラズマの電 子温度や密度などによって決まる。 When the target is irradiated with laser light, atoms and molecules in the target are optically broken down (optically broken down), ionized, and laser plasma is generated. X-rays are generated from the generated laser plasma. The laser beam intensity required for optical breakdown differs depending on the type and state of the target element. Electron temperature and density of the laser plasma, the type of elements contained in the target, and varies the laser type and conditions, the number 1 0 0 e V or more electron temperature, 1 in the electron density 0 2 ° ~ 1 0 2 Plasma of about 2 / cm 3 is generated. The X-rays generated are continuous spectra from the laser plasma due to the bremsstrahlung radiation of the electrons in the laser plasma, the free-free transition and the free-bundle transition in the plasma recombination process. X-rays are emitted, and characteristic X-rays are emitted by the process of bound-to-bound transition in the plasma recombination process. The X-ray spectrum obtained at this time depends on the type of elements contained in the target, the electron temperature and the density of the laser plasma, and the like.
一方、 レーザプラズマから X線を発生させ、 発生した X線を半導体ゥ ェハに導いて半導体ウェハに半導体装置パターンを露光する半導体装置 露光装置などでは、 発生した X線を集光する光学素子と して、 多層膜ミ ラーが用いられるが、 このミラーで反射できる波長帯は極めて限定され ている。 例えば、 図 2 に M o Z S i 多層膜ミ ラーの場合の反射率の波長 依存性の一例を示すが、 こ こ に示すよう に反射できる波長帯のバン ド幅 は、 0 . 4〜 0 . 6 n mの極めて狭い波長幅である。 ま た、 その波長帯も 多層膜ミ ラーの材料によって制約されており 、 M o / S i 多層膜ミ ラー の場合、 中心波長が 1 3 ~ 1 4 n mの間に限られている。 したがって、 このよ う なミ ラーを用いなければならない装置では、 レーザプラズマか一 ら発生する X線もこのよう なミ ラーの波長帯の X線強度が高いことが必 要となる。 すなわち、 レーザ光強度を分母と し、 利用可能な波長帯の X 線強度を分子と したと きに得られ-る X線変換率が高いことがレーザブラ ズマ X線発生装置の必須の条件となる。 On the other hand, a semiconductor device exposing device that generates X-rays from a laser plasma and guides the generated X-rays to a semiconductor wafer to expose a semiconductor device pattern onto a semiconductor wafer includes an optical element that condenses the generated X-rays. Then, a multilayer mirror is used, but the wavelength band that can be reflected by this mirror is extremely limited. For example, Fig. 2 shows an example of the wavelength dependence of the reflectance in the case of a MoZSi multilayer mirror. The band width of the wavelength band that can be reflected as shown here is 0.4 to 0.4. It has an extremely narrow wavelength width of 6 nm. Also, its wavelength band It is limited by the material of the multilayer mirror, and in the case of the Mo / Si multilayer mirror, the center wavelength is limited to 13 to 14 nm. Therefore, in an apparatus that must use such a mirror, it is necessary that the X-rays generated from the laser plasma also have a high X-ray intensity in the wavelength band of such a mirror. In other words, the essential condition of a laser plasma X-ray generator is that the X-ray conversion rate obtained when the laser beam intensity is used as the denominator and the X-ray intensity in the usable wavelength band is used as the numerator is high. .
以上の条件に対し、 従来技術のう ち、 まず、 レーザ径よ り も大きい塊 状やテープ状などの固体および液体のターゲッ 卜では、 レーザ光の照射 によって発生する熱が周辺に伝わり 、 ターゲッ トが溶融する。 そ してレ 一ザプラズマの発生に伴う膨張圧力で溶融したターゲッ トが飛散して、 数 1 0 μ mのデブリ となる。 デブリ は、 真空容器内の光学素子などに付 着して損傷を与える。  Under the above conditions, among the conventional technologies, first, in the case of a solid or liquid target such as a block or a tape having a diameter larger than the laser diameter, heat generated by the irradiation of the laser beam is transmitted to the periphery, and Melts. Then, the target melted by the expansion pressure associated with the generation of the laser plasma is scattered, resulting in debris of several 10 μm. Debris attaches to and damages optical elements in the vacuum vessel.
固体および液体のターゲッ トをレーザ径ょ リ も小さい粒子状にすれば、 周囲に粒子がないからデブリ も減少 し、 X線変換効率は固体および液体 と変わり ないが、 粒子状のターゲッ 卜の 1個 1個をレーザ光の照射にタ ィ ミ ングをあわせて安定に供給する ことは難しく 、 安定して X線を発生 させる ことも困難である。  If the solid and liquid targets are made into particles with small laser diameters, debris is reduced because there are no particles around, and the X-ray conversion efficiency is the same as that of solids and liquids. It is difficult to stably supply each of them at the same time as the irradiation of laser light, and it is also difficult to stably generate X-rays.
希ガス等の化学的に安定な気体を氷結させた粒子のターゲッ トは、 溶 融しても希ガス等の化学的に安定な気体になるので、 デブリ を発生しな いが、 供給することは難し く 、 安定して X線を発生させることも困難で ある。 また、 X線変換効率は金属ターゲッ トよ り も低い。  The target of particles formed by freezing a chemically stable gas such as a rare gas does not generate debris because it becomes a chemically stable gas such as a rare gas even when it is melted. It is difficult to generate stable X-rays. X-ray conversion efficiency is lower than that of metal targets.
一方、 気体のターゲッ トでは、 固体および液体のターゲッ トに比べて、 周囲への熱伝導が小さ く 溶融が起こ らないからデブリ は少なく 、 連続し て供給できるので安定して X線を発生させることができるが、 X線変換 効率は固体および液体よ リ も低い。 On the other hand, in gaseous targets, compared to solid and liquid targets, heat conduction to the surroundings is small and melting does not occur, so there is little debris, and it can be supplied continuously, generating stable X-rays X-ray conversion can be Efficiency is lower than solids and liquids.
更に、 金属微粒子を透明基板中に散在させたタ一ゲッ トではデブリ が 少ないことが報告されているが、 X線変換率は金属単体よ り低く 、 また 連続的にターゲッ 卜を供給するのは困難である。 発明の開示 - 本発明の第 1 目的は、 X線変換効率が高く 、 デブリ の発生が少ないレ 一ザプラズマ X線発生装置を提供する ことにあ り 、 第 2 目的はそのレー ザプラズマ X線発生装置を用いた半導体露光装置を提供することにあり 第 3 目的はそのレーザプラズマ X線発生装置を用いた半導体露光方法を 提供することにある。  Furthermore, it is reported that a target in which fine metal particles are scattered in a transparent substrate has less debris.However, the X-ray conversion rate is lower than that of a single metal, and it is difficult to supply a target continuously. Have difficulty. DISCLOSURE OF THE INVENTION-A first object of the present invention is to provide a laser plasma X-ray generator having high X-ray conversion efficiency and low debris generation, and a second object is to provide a laser plasma X-ray generator. A third object of the present invention is to provide a semiconductor exposure method using the laser plasma X-ray generator.
本発明のレーザプラズマ X線発生装置の特徴は、 金属酸化物をターゲ ッ トとすることにある。 この特徴によれば、 金属酸化物固有の高い X線 変換率が得られ、 ま た、 一般に金属酸化物の融点は、 金属単体よ り も高 いので、 溶融しに く く 、 デブリ の発生を少な く することができる。 本発明のレーザプラズマ X線発生装置の他の特徴は、 金属酸化物を微 粒子と し、 その金属酸化物微粒子の径をターゲッ トに照射されるレーザ 光の径ょ リ小さ く することにある。 この特徴によれば、 プラズマ化可能 領域によ り多く の粒子が存在するので、 確実にプラズマ化でき、 かつ、 各金属酸化物微粒子間の熱伝導は小さ く 、 レーザ照射部以外の微粒子の 溶融が起こ らないので、 デブリ の発生をよ り 少なく することができる。 本発明のレーザプラズマ X線発生装置の他の特徴は、 金属酸化物微粒 子を、 ガスとともに、 レーザ光照射部に噴射することにある。 この特徴 によれば、 粒子と気体と を混合したターゲッ トは噴射されて流体となり レーザパルスに対して常にタ一ゲッ 卜が供給されるので、 X線を安定に 発生させる ことができる。 A feature of the laser plasma X-ray generator of the present invention is that a metal oxide is a target. According to this feature, a high X-ray conversion rate unique to metal oxides can be obtained, and since the melting point of metal oxides is generally higher than that of metal alone, they are less likely to melt and generate debris. It can be reduced. Another feature of the laser plasma X-ray generator according to the present invention is that the metal oxide is made into fine particles and the diameter of the metal oxide fine particles is made smaller than that of the laser beam irradiated to the target. . According to this feature, since more particles are present in the plasmatable region, the plasma can be reliably formed, and the heat conduction between the metal oxide fine particles is small. Since debris does not occur, the generation of debris can be further reduced. Another feature of the laser plasma X-ray generator of the present invention resides in that metal oxide fine particles are injected together with gas into a laser beam irradiation section. According to this feature, the target in which the particles and the gas are mixed is ejected to become a fluid, and the target is always supplied to the laser pulse, so that the X-ray can be stably provided. Can be generated.
また、 本発明のレーザプラズマ X線発生装置の他の特徴は、 上記のよ う に供給した微粒子、 ま たはガスを回収して、 再供給する ことにある。 ― この特徴によれば、 微粒子、 またはガスを再利用できるので、 運転コス トを低減できる。  Another feature of the laser plasma X-ray generator of the present invention resides in that the fine particles or gas supplied as described above are recovered and supplied again. -According to this feature, since the fine particles or gas can be reused, the operating cost can be reduced.
また、 本発明のレーザプラズマ- X線発生装置の他の特徴は、 金属酸化 物は、 固体または焼結体であり 、 それをロ ッ ド状と して、 真空容器の外 から中へ連続的に供給し、 かつ、 レーザを照射された部分を真空容器の 中から外へ連続的に引き出すこと にある。 この特徴によれば、 連続的に 固体ま たは焼結体の金属酸化物を供給でき、 かつ、 X線変換率の高いレ 一ザプラズマ X線発生装置を構成できる。  Another feature of the laser plasma-X-ray generator of the present invention is that the metal oxide is a solid or a sintered body, which is made into a rod shape, and is continuously fed from outside to inside the vacuum vessel. And to continuously extract the laser-irradiated part from the inside of the vacuum vessel to the outside. According to this feature, a solid or sintered metal oxide can be continuously supplied and a laser plasma X-ray generator having a high X-ray conversion rate can be configured.
また、 本発明のレーザプラズマ X線発生装置の他の特徴は、 金属酸化 物が粉体状であ り 、 テープ状の基板に塗布して用いる ことにある。 ま た、 このと き、 テープ状の基板に粉体状の金属酸化物を塗布する装置と、 そ の金属酸化物が塗布されたテープを連続的にレーザ照射部に供給する装 置を有することにある。 この特徴によれば、 連続的に金属酸化物を供給 でき、 かつ、 X線変換率の高いレーザプラズマ X線発生装置を構成でき る。 ，  Another feature of the laser plasma X-ray generator of the present invention resides in that the metal oxide is in a powder form, and is applied to a tape-shaped substrate for use. At this time, it is necessary to have a device for applying powdered metal oxide to the tape-shaped substrate and a device for continuously supplying the tape coated with the metal oxide to the laser irradiation unit. It is in. According to this feature, a metal oxide can be continuously supplied, and a laser plasma X-ray generator having a high X-ray conversion rate can be configured. ,
本発明の半導体露光装置と半導体露光方法他の特徴は、 金属酸化物を ターゲッ トと した本発明のレーザプラズマ X線発生装置を用い、 そのレ 一ザプラズマ X線発生装置から発生してきた X線を集光ミ ラーがマスク に導き、 X線縮小露光ミ ラーがマスクで反射した X線を縮小して半導体 ウェハに投影する ことにある。 この特徴によれば、 レーザプラズマ X線 発生装置でデブリ の発生が少ないので、 半導体露光装置の集光ミ ラー， マスク， X線縮小露光ミ ラーなどの X線光学素子や真空隔壁の損傷を防 ぐことができる。 ま た、 レーザプラズマ X線発生装置から安定に輝度が 高い X線が供給されるので、 露光が不足することがなく 、 露光時間を短 く することができる。 図面の簡単な説明 Another feature of the semiconductor exposure apparatus and the semiconductor exposure method of the present invention is that the laser plasma X-ray generator of the present invention targeting a metal oxide is used to generate X-rays generated from the laser plasma X-ray generator. The focusing mirror guides the light to the mask, and the X-ray reduction exposure mirror reduces the X-rays reflected by the mask and projects the reduced X-rays on the semiconductor wafer. According to this feature, since the generation of debris is small in the laser plasma X-ray generator, damage to the X-ray optical elements such as the condensing mirror, mask, X-ray reduction exposure mirror, etc. of the semiconductor exposure apparatus and the vacuum partition is prevented. Can be passed. Further, since high-brightness X-rays are stably supplied from the laser plasma X-ray generator, the exposure time does not become insufficient and the exposure time can be shortened. BRIEF DESCRIPTION OF THE FIGURES
第 1 図は、 本発明の第 1 の実施例である レーザプラズマ X線発生装置 を用いた半導体露光装置の全体図である。  FIG. 1 is an overall view of a semiconductor exposure apparatus using a laser plasma X-ray generator according to a first embodiment of the present invention.
第 2図は、 M o Z S i 多層膜ミ ラーの場合の X線反射率の波長依存性 を示すグラフ図である。  FIG. 2 is a graph showing the wavelength dependence of the X-ray reflectivity in the case of a MoZSi multilayer mirror.
第 3図は、 本発明の第 1 の実施例に採用されたレーザブラズマ X線発 生装置によ り得られた X線スぺク トルを示すグラフ図。  FIG. 3 is a graph showing an X-ray spectrum obtained by the laser plasma X-ray generation apparatus employed in the first embodiment of the present invention.
第 4図は、 本発明の第 2 の実施例であるレーザプラズマ X線発生装置 を用いた半導体露光装置の全体図である。  FIG. 4 is an overall view of a semiconductor exposure apparatus using a laser plasma X-ray generator according to a second embodiment of the present invention.
第 5図は、 本発明の第 3 の実施例であるレーザプラズマ X線発生装置 の全体図である。  FIG. 5 is an overall view of a laser plasma X-ray generator according to a third embodiment of the present invention.
第 6 図は、 本発明の第 3 の実施例による レーザプラズマ X線発生装置 によ リ得られた X線の X線スぺク トルを示すグラフ図である。  FIG. 6 is a graph showing an X-ray spectrum of X-rays obtained by a laser plasma X-ray generator according to a third embodiment of the present invention.
第 7図は、 本発明の第 4の実施例である レーザプラズマ X線発生装置 の全体図である。 発明を実施するための最良の形態  FIG. 7 is an overall view of a laser plasma X-ray generator according to a fourth embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION
発明者は、 種々のターゲッ トについてレーザを照射し、 レーザプラズ マからの X線を測定した結果、 金属酸化物が金属単体やガス単体に比べ て、 大きな X線変換率を有すること を発見した。  The inventors irradiate various targets with a laser and measure X-rays from laser plasma. As a result, they have found that metal oxides have a higher X-ray conversion rate than metal alone or gas alone.
以下で、 金属酸化物を用いる X線発生装置およびそれを用いた半導体 露光装置の実施例について説明する。 Below, an X-ray generator using a metal oxide and a semiconductor using the same An embodiment of the exposure apparatus will be described.
本発明の第 1 の実施例であるレーザプラズマ X線発生装置を用いた半 導体露光装置を図 1 に示す。 半導体露光装置は、 X線を発生するレーザ ー プラズマ X線発生装置である X線発生部 1 0 0 と、 露光部 2 0 0 とから 構成される。 露光部 2 0 0は、 X線発生部 1 0 0で発生した X線 1 4 を X線集光ミ ラー 1 5でマスク 1 6 に導き、 マスク 1 6 で反射したマスク パターンを X線縮小露光ミラー 1 7 で縮小してウェハ 1 8 (試料） に投 影するものである。 図 2 に、 X線集光ミ ラー 1 5 ， マスク 1 6 、 および X線縮小露光ミラ一 1 7 に用いられる多層膜ミ ラ一の反射率の一例と し て、 M o Z S i 多層膜ミ ラーの場合の反射率の波長依存性を示す。 こ こ に示すよう に反射できる波長帯のバン ド幅は、 0 . 4 n m の極めて狭い 波長幅であ り 、 また、 その中心波長は、 この M o Z S i 多層膜ミラーの 例の場合、 中心波長が 1 3 . 7 n m である。  FIG. 1 shows a semiconductor exposure apparatus using a laser plasma X-ray generator according to a first embodiment of the present invention. The semiconductor exposure apparatus includes an X-ray generation unit 100, which is a laser plasma X-ray generation device that generates X-rays, and an exposure unit 200. The exposure unit 200 guides the X-rays 14 generated by the X-ray generation unit 100 to the mask 16 by the X-ray focusing mirror 15 and reduces the mask pattern reflected by the mask 16 to X-ray exposure. It is reduced by the mirror 17 and projected onto the wafer 18 (sample). Figure 2 shows an example of the reflectivity of the multilayer mirror used in the X-ray focusing mirror 15, the mask 16, and the X-ray reduction exposure mirror 17. 4 shows the wavelength dependence of the reflectivity in the case of ラ ー. As shown here, the band width of the wavelength band that can be reflected is an extremely narrow wavelength width of 0.4 nm, and the center wavelength is the center wavelength in the case of this MoZSi multilayer mirror. The wavelength is 13.7 nm.
次に、 レーザプラズマ X線発生装置である X線発生部 1 0 0 を詳し く 説明する。 X線発生部 1 0 0 は、 ターゲッ トの周 り を取り 囲む真空容器 5、 微粒子混合ガスをターゲッ トと して真空容器 5 内に供給するターゲ ッ ト供給装置 1 1 0 ， 微粒子混合ガスタ一ゲッ ト 1 0 にレーザ光 2 を照 射するレーザ照射装置 1 2 0 、 および真空容器 5内の微粒子混合ガスを 回収するターゲッ ト回収装置 1 3 0から構成される。  Next, the X-ray generator 100, which is a laser plasma X-ray generator, will be described in detail. The X-ray generator 100 includes a vacuum vessel 5 surrounding the target, a target supply device 110 for supplying the mixed gas of fine particles into the vacuum vessel 5 as a target, It comprises a laser irradiation device 120 for irradiating the target 10 with the laser beam 2, and a target collection device 130 for collecting the mixed gas of fine particles in the vacuum vessel 5.
ターゲッ 卜供給装置 1 1 0 は、 レーザ集光径ょ リ も小さい金属酸化物 微粒子が充填された微粒子タ ンク 6 ， ガスが充填されたガスボンベ 7， 微粒子タ ンク 6 から供給される金属酸化物微粒子と、 ガスボンベ 7 から 供給される希ガスと を混合する混合器 8 、 および混合器 8でつく られた 微粒子混合ガスを真空容器 5 中に噴射する供給ノ ズル 9 を備える。 但し、 ガスを用いず微粒子タ ンク 6 と供給ノ ズル 9 のみで金属酸化物微粒子を 供給するよう に しても良い。 The target supply device 110 includes a fine particle tank 6 filled with metal oxide fine particles having a small laser focusing diameter, a gas cylinder 7 filled with gas, and a metal oxide fine particle supplied from the fine particle tank 6. And a mixer 8 for mixing a rare gas supplied from a gas cylinder 7 and a supply nozzle 9 for injecting a mixed gas of fine particles produced by the mixer 8 into a vacuum vessel 5. However, without using gas, metal oxide fine particles were obtained only with the fine particle tank 6 and the supply nozzle 9. You may supply them.
こ こで、 用いる金属酸化物微粒子は、 C r , M n , C o , N i ， C u S r , Y， Z r ， N b， M o , A g , I n , S n， S b， B a， L a， C e， P r , N d , P m , S m , E u， T b , H o， T a， W， P bの いずれか 1つ以上の金属の酸化物であ り 、 露光部 2 0 0で用いられる X 線集光ミ ラー 1 5， マスク 1 6、 -および X線縮小露光ミラー 1 7の多層 膜ミ ラーの反射波長帯に適した X線ピークを持つものを選定するよ う に する。  Here, the metal oxide fine particles used are Cr, Mn, Co, Ni, CuSr, Y, Zr, Nb, Mo, Ag, In, Sn, Sb. , Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Ta, W, Pb. Yes, it has an X-ray peak suitable for the reflection wavelength band of the multilayer mirror of the X-ray focusing mirror 15, mask 16,-and X-ray reduction exposure mirror 17 used in the exposure unit 200 Try to select one.
レーザ照射装置 1 2 0は、 レーザ光 2を発生するレーザ光発生器 1、 およびレーザ光 2 を収束する収束レンズ 3 を備える。 レーザ光発生器 1 は、 Y A Gレーザやエキシマレーザなどの、 パルス幅が数 1 0 n s以下 で、 1パルスあたり の出力が数 1 0 m Jから数 1 0 Jのレーザ光 2 を発 生するものがよい。 レーザ光 2は、 真空容器 5中の微粒子混合ガスター ゲッ ト上で直径で数 1 0〜数 1 0 0 μ mになるよ う に収束レンズ 3で収 束される。 レーザプラズマ 1 1 を発生させるために、 微粒子混合ガスタ —ゲッ ト 1 0上でのエネルギー密度は 1 015〜 1 022 W m 2 程度がよ い The laser irradiation device 120 includes a laser light generator 1 that generates the laser light 2 and a converging lens 3 that converges the laser light 2. The laser light generator 1 generates a laser beam 2 such as a YAG laser or an excimer laser with a pulse width of several 10 ns or less and an output per pulse of several 10 mJ to several 10 J. Is good. The laser beam 2 is converged by the converging lens 3 on the fine particle mixed gas target in the vacuum vessel 5 so that the diameter becomes several 10 to several 100 μm. In order to generate the laser plasma 11, the energy density on the gaseous particle-mixed target 10 should be about 10 15 to 10 22 W m 2 .
ターゲッ ト回収装置 1 3 0は、 真空容器 5内に供給され、 プラズマ化 しなかったま たは定常状態に戻った金属酸化物微粒子およびガスを引き 込む回収ダク ト 1 2、 および回収器 1 3 を備える。  The target recovery device 130 is provided with a recovery duct 12 and a recovery device 13 which are supplied into the vacuum vessel 5 and draw metal oxide fine particles and gas which have not been turned into plasma or returned to a steady state. Prepare.
真空容器 5内には、 供給ノ ズル 9の噴射口と回収ダク ト 1 2の回収口 とが対向するよ う に配置されている。 レーザ照射装置 1 2 0からのレー ザ光 2は、 真空容器 5の壁面に設けられたレーザ光透過窓 4を透過して 供給ノ ズル 9から噴射された微粒子混合ガス 1 0に照射される。 真空容 器 5内は、 真空ポンプ （図示せず） によって低圧力に保たれている。 例 えば、 真空容器 5 中の圧力を 1 0 _2 to rr以下と し、 供給ノ ズル 9 内の圧 力を数気圧にすれば、 微粒子混合ガス 1 0 は、 噴出して流体の状態とな る。 そ して、 プラズマ化しなかったまたは定常状態に戻った微粒子混合 - ガス 1 0 は回収ダク ト 1 2 に入り 、 真空容器 5内から除去される。 In the vacuum vessel 5, the injection port of the supply nozzle 9 and the recovery port of the recovery duct 12 are disposed so as to face each other. The laser light 2 from the laser irradiation device 120 passes through the laser light transmission window 4 provided on the wall surface of the vacuum vessel 5 and irradiates the fine particle mixed gas 10 injected from the supply nozzle 9. The inside of the vacuum container 5 is maintained at a low pressure by a vacuum pump (not shown). An example Example, the pressure in the vacuum vessel 5 and below 1 0 _ 2-to rr, if the pressure in the supply Roh nozzle 9 to several atmospheres, particulate mixture gas 1 0, that Do the state of fluid ejected . Then, the particulate mixed gas 10 that has not been turned into plasma or has returned to the steady state enters the recovery duct 12 and is removed from the vacuum vessel 5.
微粒子混合ガスターゲッ ト 1 0 に収束させたレーザ光 2 を照射すると、 レーザ光 2 の強力な電場などによ リ 、 微粒子混合ガスターゲッ ト 1 0中 の金属酸化物とガスは光学的に絶縁破壊（オプティ カルブレイ クダウン） を してイオン化する。 イオン化によ り発生した電子が、 逆制動輻射など の過程によ リ レーザ光 2 のエネルギーを吸収して加熱され、 微粒子混合 ガスターゲッ ト 1 0のレーザ光 2 が貫く 範囲に、 高温高密度なレーザプ ラズマ 1 1 が形成される。  When the laser beam 2 converged on the particulate mixed gas target 10 is irradiated, the metal oxide and gas in the particulate mixed gas target 10 are optically dielectrically broken by the strong electric field of the laser beam 2 and the like. (Optical breakdown) to ionize. The electrons generated by the ionization absorb the energy of the laser beam 2 through processes such as reverse braking radiation and are heated, so that the high-temperature and high-density areas are within a range where the laser beam 2 of the gas target 10 is mixed. A laser plasma 11 is formed.
レーザプラズマ 1 1 の電子温度や密度は、 微粒子混合ガスターゲッ ト 1 0 に含まれる金属酸化物とガスの種類、 およびレーザの種類や条件に よって異なるが、 電子温度で数 1 O O e V以上、 電子密度で 1 0 2 °〜 1 0 2 2 / cm3 程度のプラズマが発生すると よい。 The electron temperature and density of the laser plasma 11 vary depending on the type of metal oxide and gas contained in the particulate mixed gas target 10 and the type and conditions of the laser. 1 in the electron density 0 2 ° ~ 1 0 may 2 2 / cm 3 about the plasma is generated.
レーザプラズマ 1 1 中の電子の制動輻射、 プラズマの再結合過程にお ける自由一自由遷移や自由一束縳遷移の過程によ リ 、 レーザプラズマ Laser plasma 11 Due to the bremsstrahlung emission of electrons in the plasma, free-free transition and free-bundle-transition process in the plasma recombination process,
1 1 から連続的なスペク トルの X線が放出され、 ま た、 プラズマの再結 合過程における束縛一束縛遷移の過程によ リ 、 特性 X線が放出される。 レーザプラズマ 1 1 から放出された X線は隣接する露光部 2 0 0で用い られる。 X-rays of a continuous spectrum are emitted from 11 and characteristic X-rays are emitted due to the bound-to-bound transition in the plasma recombination process. X-rays emitted from the laser plasma 11 are used in the adjacent exposure unit 200.
こ こで、 本実施例によ り得られた X線スペク トルを図 3 に示す。 この 例では、 金属酸化物と して S n 0 2 の微粒子 （粒径 ： 約 1 0 n m ) を用 い、 A r ガス （ボンべガス圧 ： 7気圧） とともに供給ノ ズル 9から噴射 して、 そこにレーザ光 （出力 ： 7 0 0 m J //パルス、 パルス幅 ： 5 n s 、 波長 ： 1 0 6 4 n m ) をレンズ （焦点距離 ： 2 0 0 mm) で集光して照射 した。 S n 02微粒子を入れずに、 02ガス、 希ガス （ X e， K r ) のみ を噴射した場合のスぺク トルも合わせて示している。 この図からわかる よ う に、 S n 02微粒子 + A r では 1 3. 7 n mを中心と した強いピーク があるのに対して、 X e， K r のみでは、 1 3〜 1 4 n mの領域ではX 線強度が弱いことがわかる。 したがって、 M 0 / S i 多層膜ミ ラ一を用 いる場合においては、 S n 02 微粒子 + A r では、 X e， K r のみの場 合よ り も、 約 2倍以上の X線変換率が得られている。 こ こで、 S n 02 微粒子において 1 3. 7 n m を中心と した強いピークが得られる原因を 考える。 まず、 02 ガスが図 3 に示すよう に 1 0〜 1 3 n mの間にいく つかのピーク を持っており 、 一方、 S n 自体は、 図 6 に示すよう に 1 3 ~ 1 6 n mにかけてブロー ドなピーク を持っている。 従って、 S n 02 の場合では、 02 ガスで 1 0〜 1 3 n mのピーク を発する準位に励起さ れたエネルギーが、 そのエネルギー近傍の S nのエネルギー準位に移行 し、 1 3. 7 n mのピーク を形成していると考えられる。 Here, FIG. 3 shows the X-ray spectrum obtained by the present embodiment. In this example, as a metal oxide S n 0 2 fine particles (particle size: about 1 0 nm) have use a, A r gas (cylinder gas pressure: 7 atm) and injected from the supply Roh nozzle 9 with , There laser light (output: 700 mJ // pulse, pulse width: 5 ns, (Wavelength: 1064 nm) was condensed by a lens (focal length: 200 mm) and irradiated. Without putting the S n 0 2 particles, 0 2 gas, a rare gas (X e, K r) are also combined show scan Bae-vector in the case of injecting only. Ni Let 's can be seen from this figure, while the there is a strong peak around the 1 3. 7 nm in S n 0 2 particles + A r, X e, alone K r, of 1. 3 to 1 4 nm It can be seen that the X-ray intensity is weak in the region. Accordingly, in a case where there use the M 0 / S i multilayer Makumi La scratch, the S n 0 2 particles + A r, X e, even Ri by case of K r only, about 2 times more X-ray conversion Rate has been obtained. In here, consider the cause of strong peak around the 1 3. 7 nm in S n 0 2 particles are obtained. First, 0 2 gas has a peak of several going between 1 0 to 1 3 nm, as shown in FIG. 3, on the other hand, S n itself is subjected to 1 3 ~ 1 6 nm as shown in FIG. 6 Has a broad peak. Thus, S in the case n of 0 2, 0 1 0 to 1 3 nm energy excited state to emit peak at 2 gas, it shifted to the energy level of the S n of its energy near 1 3 It is considered that a peak at 7 nm was formed.
本実施例によれば、 以下の効果が得られる。  According to this embodiment, the following effects can be obtained.
本実施例では、 金属酸化物微粒子とガスと を混合した微粒子混合ガス ターゲッ トを用いる こ と によ り 、 多層膜ミラ一の反射波長帯における X 線変換効率が、 希ガスターゲッ トよ り も高い。  In the present embodiment, by using the fine particle mixed gas target in which the metal oxide fine particles and the gas are mixed, the X-ray conversion efficiency in the reflection wavelength band of the multilayer mirror is higher than that of the rare gas target. high.
金属酸化物微粒子混合ガスターゲッ トは,、 金属酸化物の熱伝導が小さ く 、 ま た、 レーザ照射部以外の金属酸化物微粒子への熱伝導が極めて少 ないので、 レーザ照射部以外の金属酸化物微粒子の溶融が起こ らず、 デ ブリ を少なく できる。  The metal oxide fine particle mixed gas target has a low thermal conductivity of the metal oxide and a very low heat conduction to the metal oxide fine particles other than the laser irradiated part, so that the metal oxide other than the laser irradiated part is not oxidized. Debris can be reduced because the material particles do not melt.
本実施例では、 金属酸化物微粒子とガスと を混合したターゲッ トを真 空容器 5内に噴射し、 噴射されて流体となったタ一ゲッ トにレーザ光が 照射されるので、 レーザパルスに対して常にターゲッ トが供給されるの で、 X線を安定に発生させることができる。 In this embodiment, a target in which metal oxide fine particles and a gas are mixed is injected into the vacuum container 5, and a laser beam is applied to the target that has been injected and becomes a fluid. Since irradiation is performed, the target is always supplied to the laser pulse, so that X-rays can be generated stably.
本実施例では、 プラズマ化しなかったターゲッ トを回収するので、 真 空容器 5 内を低圧に保つこ とができ、 発生した X線の吸収損失を防ぐこ とができる。  In the present embodiment, since the target that has not been turned into plasma is recovered, the inside of the vacuum container 5 can be kept at a low pressure, and absorption loss of generated X-rays can be prevented.
本発明の第 2 の実施例を図 4 に-よ り説明する。 本実施例は、 第 1 の実 施例におけるターゲッ トの回収器 1 3 に金属酸化物微粒子とガスを分離 する分離器 3 0 を設け、 回収器 1 3で回収したターゲッ トの内、 ガスと 金属酸化物微粒子と を分離器 3 0で分離して回収し、 分離後の金属酸化 物微粒子は元の微粒子タ ンク 6へ及び分離後のガスはガスボンベ 7 に戻 して リサイ クルするよ う にしたものである。 その他の内容は本発明の第 1 の実施例と同様である。  A second embodiment of the present invention will be described with reference to FIG. In the present embodiment, a separator 30 for separating metal oxide fine particles and gas is provided in the target collector 13 in the first embodiment, and the gas collected from the target collected in the collector 13 The metal oxide fine particles are separated and recovered by a separator 30, and the separated metal oxide fine particles are returned to the original fine particle tank 6 and the separated gas is returned to the gas cylinder 7 for recycling. It was done. Other contents are the same as those of the first embodiment of the present invention.
よって、 本実施例によれば、 第 1 の実施例の効果に加えて、 装置メ ン テナンスが低減でき、 ま た、 ランニングコス トが低減できるという効果 がある。  Therefore, according to the present embodiment, in addition to the effects of the first embodiment, there is an effect that the device maintenance can be reduced and the running cost can be reduced.
本発明の第 3 の実施例を図 5 によ り説明する。 本実施例は、 金属酸化 物を固体または焼結体と したものをターゲッ トと して用いる。 図 5 にお いては、 金属酸化物の固体ま たは焼結体をロ ッ ド状ターゲッ ト 2 3 と し て、 ロ ッ ド挿入器 2 4 によ り 、 真空容器 5へ連続的に挿入し、 レーザ照 射されたロ ッ ド状ターゲッ ト 2 3 を真空容器外へ取り出すよう に したも のである。  A third embodiment of the present invention will be described with reference to FIG. In this embodiment, a solid or sintered metal oxide is used as a target. In FIG. 5, a solid or sintered body of metal oxide is continuously inserted into a vacuum vessel 5 by a rod inserter 24 as a rod-shaped target 23. Then, the rod-shaped target 23 irradiated with the laser is taken out of the vacuum vessel.
このよ う に金属酸化物を固体または焼結体と した場合に得られた X線 スペク トルを図 6 に示す。 この例では、 金属酸化物と して S n 0 2 固体 を用いて、 そこにレーザ光 （出力 ： 7 0 0 m J //パルス、 パルス幅 ： 5 n s 、 波長 ： 1 0 6 4 n m ) をレンズ （焦点距離 ： 2 0 0 mm ) で集光し て照射した。 比較のために、 金属単体（ S n， A u , N i )のみの場合の スペク トルも合わせて示している。 この図からわかるよ う に、 S n 02 固体では、 図 3の場合と同様に 1 3. 7 n m を中心と した強いピークが一 あるのに対して、 金属単体のみでは、 X線強度が弱いことがわかる。 し たがって、 M o / S i 多層膜ミラ一を用いる場合においては、 S n 02 固体では、 S n , A u , N i 金属-単体の場合よ り も、 約 3倍以上の X線 変換率が得られている。 Figure 6 shows the X-ray spectrum obtained when the metal oxide was used as a solid or sintered body. In this example, using S n 0 2 solid as the metal oxide, there laser beam (output: 7 0 0 m J // pulse, pulse width: 5 ns, wavelength: 1 0 6 4 nm) to Focus with a lens (focal length: 200 mm) Irradiated. For comparison, the spectra for simple metals (Sn, Au, Ni) alone are also shown. Ni Let 's can be seen from this figure, the S n 0 2 solid, whereas strong peak around the 1 3. 7 nm as in the case of FIG. 3 is one, with only simple metal, the X-ray intensity You can see that it is weak. Therefore, in the case of using a M o / S i multilayer mirror scratch, in the S n 0 2 solid, S n, A u, N i metal - even Ri by case alone, about 3 times more X-ray Conversion rates have been obtained.
このよ う に得られた X線は本発明の第 1実施例の露光部 2 0 0内に導 入されて、 本発明の第 1実施例と同様に半導体のウェハ 1 8へのマスク パターンの投影に用いられる  The X-rays thus obtained are introduced into the exposure unit 200 of the first embodiment of the present invention, and a mask pattern is formed on a semiconductor wafer 18 similarly to the first embodiment of the present invention. Used for projection
なお、 本発明の第 1 の実施例と同様に、 こ こで、 用いる金属酸化物微 粒子は、 C r , M n , C o， N i , C u , S r , Y， Z r， N b， M o , A g , I n , S n， S b , B a , L a , C e， P r， N d , P m , S m , E u， T b， H o， T a , W， P bのいずれか 1つ以上の金属の酸化物 であ り 、 露光部 2 0 0で用いられる X線集光ミ ラー 1 5， マスク 1 6、 および X線縮小露光ミ ラ一 1 7の多層膜ミ ラ一の反射波長帯に適した X 線ピーク を持つものを選定するよう にする。 その他の内容は、 本発明の 第 1実施例と同様である。  Note that, similarly to the first embodiment of the present invention, the metal oxide fine particles used here are Cr, Mn, Co, Ni, Cu, Sr, Y, Zr, and Nr. b, Mo, Ag, In, Sn, Sb, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Ta, It is an oxide of one or more of the metals W and Pb, and is an X-ray focusing mirror 15, mask 16 and X-ray reduction exposure mirror 17 used in the exposure unit 200. The one that has an X-ray peak suitable for the reflection wavelength band of the multilayer mirror is selected. Other details are the same as in the first embodiment of the present invention.
本実施例によれば、 以下の効果が得られる。  According to this embodiment, the following effects can be obtained.
本実施例では、 金属酸化物固体を用いる,こ と によ り 、 多層膜ミ ラーの 反射波長帯における X線変換効率が、 金属単体ターゲッ 卜よ り も高い。 金属酸化物固体は、 金属酸化物自身の熱伝導が小さいので、 レーザ照 射部以外の金属微粒子溶融が少なく 、 デブリ を低減できる。  In this embodiment, the metal oxide solid is used, so that the X-ray conversion efficiency in the reflection wavelength band of the multilayer mirror is higher than that of the metal single target. Since the metal oxide solid has a low thermal conductivity, the metal oxide solid is less likely to melt the metal fine particles other than the laser irradiating portion, thereby reducing debris.
本実施例では、 金属酸化物固体を真空容器 5内に連続的に供給できる ので、 X線を安定に発生させることができる。 本発明の第 4の実施例を図 7によ り説明する。 本実施例は、 金属酸化 物を粉体状と し、 テープ状の基板に塗布して用いる。 図 7 において、 金 属酸化物塗布装置 2 8によ り 、 テープ状ターゲッ ト 2 5の表面に粉体状 ― の金属酸化物を塗布する。 塗布の方法は、 粉体状の金属酸化物を溶剤に 分散させ、 それをスプレーで塗布する方法や粉体状の金属酸化物を溶剤 に分散させたその溶剤中にテープ-状ターゲッ ト 2 5 を浸して塗布する方 法が適用できる。 塗布後に、 乾燥する手段を金属酸化物塗布装置 2 8に 組み込んでも良い。 粉体状の金属酸化物を塗布されたテープ状ターゲッ ト 2 5は、 テープ揷入器 2 6や、 ロール 2 7から構成されるテープ状タ 一ゲッ ト供給再生系 1 4 0によ り 、 レーザ照射部に供給され、 レーザ照 射後に、 ま た、 金属酸化物塗布装置 2 8で再塗布されて、 連続的に使用 される。 得られる X線スペク トルは図 6と同様であ り 、 M o Z S i 多層 膜ミ ラーを用いる場合においては、 S n 02 固体では、 S n , A u , F e， N i 金属単体の場合よ り も、 約 3倍以上の X線変換率が得られる。 こ のよ う に得られた X線は本発明の第 1実施例の露光部 2 0 0内に導 入されて、 本発明の第 1実施例と同様に半導体のウェハ 1 8へのマスク パターンの投影に用いられる In the present embodiment, since the metal oxide solid can be continuously supplied into the vacuum vessel 5, X-rays can be generated stably. A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, a metal oxide is made into a powdery form and applied to a tape-shaped substrate. In FIG. 7, a powdery metal oxide is applied to the surface of the tape-like target 25 by a metal oxide applying device 28. The method of application is to disperse the powdered metal oxide in a solvent and then apply it by spraying, or to disperse the powdered metal oxide in the solvent and then use the tape-like target 25 in the solvent. A method of dipping and applying is applicable. After the coating, a drying means may be incorporated in the metal oxide coating device 28. The tape-like target 25 coated with the powdered metal oxide is supplied by a tape-like target supply / reproduction system 140 composed of a tape inserter 26 and a roll 27. It is supplied to the laser irradiating unit, and after the laser irradiation, is re-coated by the metal oxide coating device 28 and is used continuously. Resulting X-ray spectrum is Ri similar der to FIG. 6, in the case of using a M o ZS i multilayer Makumi error, in S n 0 2 solid, S n, A u, F e, of the N i single metal More than three times the X-ray conversion rate can be obtained. The X-rays thus obtained are introduced into the exposure unit 200 of the first embodiment of the present invention, and a mask pattern on a semiconductor wafer 18 is formed in the same manner as in the first embodiment of the present invention. Used to project
なお、 こ こで、 用いる金属酸化物微粒子は、 C r , M n , F e , C o， N i ， C u , Z n， S r , Y， Z r , N b， o , A g , I n , S n , S b， B a , L a , C e , P r， N d , P m, S m， E u， T b， H o， T a， W， P bのいずれか 1 つ以上の金属の酸化物であ り 、 露光部 200 で用いられる X線集光ミ ラー 1 5， マスク 1 6、 および X線縮小露光ミ ラー 1 7の多層膜ミ ラ一の反射波長帯に適した X線ピーク を持つものを 選定するよ う にする。 その他の内容は本発明の第 1実施例と同様である。 本実施例によれば、 以下の効果が得られる。 本実施例では、 金属酸化物粉体を表面に塗布したテープ状ターゲッ ト を用いるこ と によ り 、 多層膜ミ ラ一の反射波長帯における X線変換効率 が、 金属単体ターゲッ トよ り も高い。 The metal oxide fine particles used here are Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Nb, o, Ag, Any one of In, Sn, Sb, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Ta, W, and Pb. It is an oxide of one or more metals, and has a reflection wavelength band of the multilayer mirror of the X-ray focusing mirror 15, mask 16, and X-ray reduction exposure mirror 17 used in the exposure unit 200. Try to select one with a suitable X-ray peak. Other details are the same as in the first embodiment of the present invention. According to this embodiment, the following effects can be obtained. In this embodiment, the use of the tape-shaped target coated with the metal oxide powder on the surface makes the X-ray conversion efficiency in the reflection wavelength band of the multilayer mirror higher than that of the single metal target. high.
金属酸化物粉体は、 金属酸化物自身の熱伝導が小さいので、 レーザ照 射部以外の金属微粒子溶融が少なく 、 デブリ を低減できる。  Since the metal oxide powder itself has low heat conduction, the metal oxide powder has little melting of metal fine particles other than the laser irradiating portion, and can reduce debris.
本実施例では、 金属酸化物粉体-を表面に塗布したテープ状ターゲッ ト を真空容器 5 内に連続的に供給できるので、 X線を安定に発生させるこ とがで きる。  In this embodiment, since a tape-like target having a surface coated with a metal oxide powder can be continuously supplied into the vacuum vessel 5, X-rays can be stably generated.
本発明のいずれの実施例であっても、 以下の効果が得られる。  In any of the embodiments of the present invention, the following effects can be obtained.
レーザプラズマ X線発生装置に用いられるターゲッ トと して金属酸化 物を用いる こ と によ り 、 露光部に用いられている多層膜ミ ラーの反射波 長帯における X線変換効率が、 従来知られていた希ガスや金属単体のタ 一ゲッ トよ り も高い。  By using a metal oxide as a target for a laser plasma X-ray generator, the X-ray conversion efficiency in the reflected wavelength band of a multilayer mirror used in an exposure unit has been known. It is higher than the target of rare gas or metal alone.
更には、 その金属酸化物は熱伝導が小さ く 、 レーザ照射部以外の金属 酸化物の溶融が起こ り に く く て、 デブリ を低減できる。  Further, the metal oxide has low heat conduction, and the metal oxide is hardly melted in portions other than the laser irradiated portion, so that debris can be reduced.

Claims

請 求 の 範 囲 The scope of the claims
1 . レーザ光をターゲッ トに照射してプラズマを生成し、 そのプラズマ から X線を発生させるレーザプラズマ X線発生装置において、 一 前記ターゲッ トは金属酸化物である こ と を特徴とする レーザプラズマ X線発生装置。  1. A laser plasma X-ray generator that irradiates a target with laser light to generate plasma and generates X-rays from the plasma, wherein the target is a metal oxide. X-ray generator.
2. 前記金属酸化物は、 C r， M-n , C o , N i , C u , S r , Y， 2. The metal oxide is composed of Cr, M-n, Co, Ni, Cu, Sr, Y,
Z r , N b , M o， A g , I n , S n， S b， B a , L a , C e , P r , N d , P m , S m， E u , T b， H o， T a , W， P bのいずれか 1つ 以上の金属の酸化物であること を特徴とする請求項 1 のレーザプラズマZr, Nb, Mo, Ag, In, Sn, Sb, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho 2. The laser plasma according to claim 1, wherein the oxide is a metal oxide of at least one of T, T, W, and Pb.
X線発生装置。 X-ray generator.
3. 前記金属酸化物は、 前記金属酸化物に照射される レーザ光の径ょ リ 小さい微粒子であることを特徴とする請求項 1 のレーザプラズマ X線発 生装置。  3. The laser plasma X-ray generator according to claim 1, wherein the metal oxide is a fine particle having a small diameter of a laser beam applied to the metal oxide.
4. 前記金属酸化物微粒子は、 ガスとともに、 前記レーザ光照射部に噴 射される ことを特徴とする請求項 3のレーザプラズマ X線発生装置。 4. The laser plasma X-ray generator according to claim 3, wherein the metal oxide fine particles are injected into the laser beam irradiation section together with a gas.
5. 請求項 3において、 前記金属酸化物を真空容器内に噴射するターゲ ッ ト供給装置と、 前記ターゲッ ト供給装置の噴射口に対向 して開口する 回収口を有して前記金属酸化物を回収するターゲッ ト回収装置と、 噴射 された前記金属酸化物にレーザ光を照射するレーザ照射装置と を備えて ある ことを特徴とするレーザプラズマ X線発生装置。 5. The target supply device for injecting the metal oxide into a vacuum container according to claim 3, and a recovery port opened opposite to an injection port of the target supply device to discharge the metal oxide. A laser plasma X-ray generator, comprising: a target collection device for collecting; and a laser irradiation device for irradiating the injected metal oxide with laser light.
6. 請求項 4において、 前記金属酸化物を前記ガスとともに真空容器内 に噴射するターゲッ ト供給装置と、 前記ターゲッ ト供給装置の噴射口に 対向 して開口する回収口を有して前記金属酸化物と前記ガスとをそれぞ れを回収するターゲッ 卜回収装置と、 前記ターゲッ ト回収装置で回収し た前記金属酸化物と前記ガスとを分離して前記ターゲッ ト供給装置側に 再供給する手段と、 噴射された前記金属酸化物にレーザ光を照射するレ 一ザ照射装置と を備えてある こ と を特徴とするレーザプラズマ X線発生 6. The metal oxide according to claim 4, comprising a target supply device for injecting the metal oxide into the vacuum vessel together with the gas, and a recovery port opened to face an injection port of the target supply device. A target recovering device for recovering the object and the gas, respectively; and a metal oxide and the gas recovered by the target recovering device, which are separated from each other to the target supply device side. Laser plasma X-ray generation, comprising: a re-supply unit; and a laser irradiation device for irradiating the injected metal oxide with a laser beam.
7 . 請求項 1 において、 金属酸化物は、 固体ま たは焼結体である ことを 特徴とする レーザプラズマ X線発生装置。 7. The laser plasma X-ray generator according to claim 1, wherein the metal oxide is a solid or a sintered body.
8 . 請求項 7 において、 金属酸化物の固体ま たは焼結体を口 ッ ド状と し て真空容器の外から中へ連続的に供給し、 かつ、 前記真空容器内でレー ザ光の照射を受けた部分を前記真空容器の中から外へ連続的に引き出す 構成を備えたこ と を特徴とするレーザプラズマ X線発生装置。  8. The method according to claim 7, wherein the solid or sintered body of the metal oxide is continuously supplied from the outside to the inside of the vacuum vessel in the form of a pad, and the laser light is supplied inside the vacuum vessel. A laser plasma X-ray generator, characterized in that the irradiated portion is continuously drawn out of the vacuum vessel.
9 . 請求項 1 において、 金属酸化物は、 粉体状であ り 、 テープ状の基板 に塗布して用いる こ とを特徴とするレーザプラズマ X線発生装置。 9. The laser plasma X-ray generator according to claim 1, wherein the metal oxide is in a powder form, and is used by being applied to a tape-shaped substrate.
1 0 . 請求項 9 において、 テープ状の基板に粉体状の金属酸化物を塗布 する装置と、 その金属酸化物が塗布されたテープを連続的にレーザ光の 照射領域に供給する装置を有する こ とを特徴とするレーザプラズマ X線 発生装置。 10. The device according to claim 9, comprising: a device for applying the powdered metal oxide to the tape-shaped substrate; and a device for continuously supplying the tape coated with the metal oxide to the laser light irradiation area. A laser plasma X-ray generator characterized by this.
1 1 . 請求項 1 から請求項 1 0 までのいずれか一項に記載のレーザブラ ズマ X線発生装置と、 前記レーザプラズマ X線発生装置で発生した X線 をマスク に導く 集光ミ ラーと、 前記マスクで反射した X線を縮小して半 導体ウェハに投影する X線縮小露光ミ ラーとを備える こ とを特徴とする 半導体露光装置。 ，  11. The laser plasma X-ray generator according to any one of claims 1 to 10, and a focusing mirror that guides an X-ray generated by the laser plasma X-ray generator to a mask. An X-ray reduction exposure mirror for reducing X-rays reflected by the mask and projecting the reduced X-rays on a semiconductor wafer. ,
1 2 . レーザ光をターゲッ トに照射してプラズマを生成させ、 そのブラ ズマから X線を発生させ、 その発生した X線をマスク に反射させ、 その 反射 X線を縮小 して半導体ウェハに投影して露光する半導体露光方法に おいて、 前記ターゲッ トと して金属酸化物を用いることを特徴とする半 導体露光方法。  1 2. The target is irradiated with laser light to generate plasma, X-rays are generated from the plasma, the generated X-rays are reflected on a mask, and the reflected X-rays are reduced and projected onto a semiconductor wafer. A semiconductor exposure method, wherein a metal oxide is used as the target.
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