JP2010080409A - Extreme ultraviolet light source device equipped with gas flow type spf - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EUV light source device having improved extreme ultraviolet light (EUV) output efficiency by removing exciting carbon dioxide laser. <P>SOLUTION: The EUV light source device includes a target supply device 5 for supplying a target material into a vacuum chamber, an exciting laser condensing optical system for irradiating the target material 4 with CO<SB>2</SB>laser beams injected from a laser inlet 34 to emit emitted light beams 10 including EUV light, an EUV condensing optical system for condensing the emitted light beams on an intermediate condensing point (IF), a spectrum purifying filter (SPF) 6 for selecting the EUV light from the emitted light beams and supplying it to external equipment, and a gas curtain device 45 having a slit nozzle 43 for jetting gas and a gas sink 47 opposed thereto for sucking the gas, for forming gas curtain in the optical path of the emitted light beams. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an extreme ultraviolet light source device that irradiates a target material with laser light to generate plasma and emits extreme ultraviolet (EUV) light, and in particular, eliminates the influence of carbon dioxide laser light irradiated to the target material and has high purity extreme ultraviolet. The present invention relates to an extreme ultraviolet light source device that supplies light.

  In recent years, along with the miniaturization of semiconductor processes, the miniaturization of optical lithography has rapidly progressed, and in the next generation, fine processing of 100 to 70 nm, and further fine processing of 50 nm or less have been required. . Therefore, for example, development of an exposure apparatus that combines an EUV light source having a wavelength of about 13 nm and a reduced projection reflective optics is expected.

  As an EUV light source, there is an LPP (laser produced plasma) light source (hereinafter also referred to as “LPP type EUV light source device”) using plasma generated by irradiating a target with a laser beam.

  In the LPP type EUV light source device, a target material is ejected from a nozzle and irradiated with a laser beam toward the target material, thereby exciting the target material into plasma. This plasma emits various wavelength components including extreme ultraviolet (EUV) light. Therefore, a desired EUV light is selected using a condensing mirror (EUV condensing mirror) that selectively reflects and collects light of a predetermined wavelength, and is output to an external device such as an exposure apparatus. For example, when condensing EUV light having a wavelength of around 13.5 nm, a condensing mirror in which a film (Mo / Si multilayer film) in which molybdenum and silicon are alternately laminated is formed on a reflection surface is used.

Conventionally, as disclosed in Patent Document 1, a spectrum purification filter (SPF: Spectrum Purity Filter) has been used in an LPP type EUV light source device to remove components unnecessary for EUV exposure from the spectrum emitted by EUV plasma. It was. In the disclosed technology, as shown in FIG. 4, for example, tin (CO ₂ ) laser light (infrared ray having a wavelength of 10.6 μm) is guided and condensed in an EUV vacuum chamber and supplied by a target supply device, for example, tin ( Sn) Irradiating a target such as a droplet to form plasma, condensing light emitted from the plasma with an EUV mirror, spectroscopically using a planar grating type SPF, and EUV light centering on a wavelength of 13.5 nm (in the figure) (-1st order light) alone is guided to the optical system of the exposure machine not shown.

  By arranging a thin film filter between the exposure machine and the EUV vacuum chamber, the Sn target material introduced into the EUV vacuum chamber and Sn debris scattered from the target plasma are prevented from flowing into the exposure machine side, and the exposure apparatus The internal optical components are not contaminated. This thin film filter also acts as an SPF by selecting a material such as Zr or Si, which has a EUV light transmittance centered at a wavelength of 13.5 nm, which is higher than other wavelengths. In the conventional LPP type EUV light source device shown in FIG. 4, the light that is split and eliminated by the planar grating type SPF is incident on a damper provided adjacent to the periphery of the thin film filter and absorbed to become thermal energy. It is carried out.

  Of the light emitted from the target plasma, light having a wavelength of 130 to 400 nm sensitizes the exposure resist used in the EUV exposure machine, which causes a reduction in exposure contrast. Infrared light is absorbed by optical components, masks, wafers, etc. in the exposure machine and may cause thermal expansion, which may reduce patterning accuracy. EUV light is generated.

In Patent Document 2, a gas curtain in which molecules do not have an absorptivity for EUV and a combination of a necessary number of gases having a large absorptivity at a wavelength to be excluded is used as an SPF. Are listed. However, the description of Patent Document 2 is an alkane having a specific example of methane, methanol, formic acid or the like to filter infrared radiation in the wavelength range of 2.85 μm to 3.55 μm as a technique used for removing infrared rays. alcohol, alone carboxylic acid, water teaches that it is effective, no mention for the other wavelength regions also this other absorbent gas, namely CO ₂ laser absorbing gas for wavelength region and CO ₂ laser in the infrared .

Furthermore, in Patent Document 3, the EUV light output of the LPP type EUV light source device is effectively obtained by using a gas curtain using a gas of zirconium chloride ZrCl ₄ or pentaborane B ₅ H ₁₁ that allows the target EUV light to pass well. It is disclosed to purify. However, Patent Document 3 does not disclose or teach any attenuation ability of the gas used for the gas curtain with respect to the CO ₂ laser.

By the way, in the LPP type EUV light source device using the CO ₂ laser as an excitation source of the Sn target, high output CO ₂ laser light (infrared light having a wavelength of 10.6 μm) is scattered and reflected by the target and mixed with EUV light. In this case, for example, it is required that the intensity of EUV light having a center wavelength of 13.5 nm is 1, and the intensity is suppressed to 0.1 or less.
The above prior art has the following problems particularly from the viewpoint of removing CO ₂ laser light from unnecessary light.

1) Since the transmittance of the SPF of the thin film filter that separates the exposure device and the EUV light source is as low as about 40%, the output efficiency of EUV light becomes very poor. In addition, the thin film is easily damaged by the incidence of debris, and if the debris adheres, the debris absorbs EUV light and the temperature rises and the filter itself may melt, so that the function as an SPF is maintained. Is difficult.
2) In SPF using an aperture (array), the aperture ratio is improved while maintaining the structural strength of the SPF, the efficiency of EUV light output to the exposure machine is improved, and the reflectivity of the CO ₂ laser to be blocked is improved. In other words, there is a problem of suppressing the risk of deformation and breakage due to temperature rise caused by light absorption. In addition, fine fluctuations in the light intensity distribution of EUV light generated in the aperture array may disturb the exposure uniformity of the semiconductor and cause exposure unevenness.
3) In SPF using the selective absorption action of gas, unnecessary light other than the intended EUV light is absorbed, but the gas species suitable for absorbing the above-mentioned CO ₂ laser light which is the object of the present invention is It is not clear.
US Pat. No. 6,809,327 JP 2007-129209 A US Patent Application Publication No. 2007 / 0012889A

Therefore, the problem to be solved by the present invention is to irradiate the target material with carbon dioxide (CO ₂ ) laser light to generate plasma, emit extreme ultraviolet (EUV) light, and collect it at the intermediate condensing point (IF) with an EUV mirror. An LPP-type extreme ultraviolet light source device that emits light and supplies it to an external device is to provide an EUV light source device that reduces the CO ₂ laser light in the output light and increases the ratio of EUV light.

In order to solve the above problems, an extreme ultraviolet (EUV) light source device of the present invention includes a target supply device that supplies a target material into a vacuum chamber, a laser light inlet that introduces carbon dioxide (CO ₂ ) laser light, and a laser. An excitation laser condensing optical system that emits radiation light including extreme ultraviolet (EUV) light by irradiating the target material supplied from the target supply device with the CO ₂ laser light incident from the introduction port to generate plasma, and this EUV light An EUV condensing optical system for condensing the radiated light including the EUV light to the intermediate condensing point (IF), a spectral purification filter (SPF) for selecting EUV light from the radiated light including the EUV light, and supplying the gas to an external device; A gas passage that includes a slit nozzle that jets out and a gas sink that sucks gas opposite to the nozzle and forms a gas curtain in the optical path of the emitted light. To.

By flowing a gas that absorbs CO ₂ laser beam to the gas passage, to reduce the CO ₂ laser beam can be released to increase the purity of the extreme ultraviolet.
In particular, when a gas containing sulfur hexafluoride (SF ₆ ) is used in the gas flow, the CO ₂ laser light is absorbed well, so that the purity of extreme ultraviolet light can be increased efficiently. Further, SF _6, when the energy density intensity of CO ₂ laser light is low, high absorption rate, the energy density high strength portion of the CO ₂ laser beam has a non-linear absorption rate performance absorptivity decreases. Therefore, if the gas curtain of SF ₆ is used as an SPF, even when the gas is filled in the vacuum chamber, the CO ₂ laser is condensed to excite EUV plasma and the light energy density intensity becomes very high. In this case, it is possible to obtain a purposeful SPF that absorbs less and effectively absorbs the CO ₂ laser light having a low energy density intensity after being scattered and reflected by the target or EUV plasma. The gas curtain is preferably formed using a supersonic nozzle. This is because the gas flow supplied from the supersonic nozzle is difficult to spread, and thus the gas does not easily leak into the room.

In addition, if the CO ₂ laser beam to be plasma is attenuated by the gas that absorbs the CO ₂ laser beam, the plasma efficiency of the target material is reduced, so that a buffer gas is supplied into the optical path of the excitation laser focusing optical system. It is preferable to provide a mechanism for exhausting a gas that absorbs CO ₂ laser light such as SF ₆ in the optical path of the excitation laser focusing optical system with a buffer gas.

By applying it to an EUV light source device that supplies EUV light to an exposure machine, etc., the CO ₂ laser light is prevented from leaking into the exposure machine, etc., and deformation / breakage caused by the temperature rise accompanying absorption of the CO ₂ laser light It is possible to provide a precise EUV light with high output efficiency.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, the same reference number is attached | subjected to the same component and description is abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of an extreme ultraviolet (EUV) light source apparatus according to a first embodiment of the present invention. The EUV light source apparatus according to the present embodiment employs a laser excited plasma (LPP) system that generates EUV light by irradiating a target material with carbon dioxide (CO ₂ ) laser light and exciting it. This is an example in which a gas absorption type spectral purification filter (SPF) is formed by flowing a gas that absorbs CO ₂ laser light like a curtain. It is particularly effective to use sulfur hexafluoride (SF ₆ ) as the CO ₂ laser absorption gas.

The EUV light source device of FIG. 1 has a CO ₂ laser device, an EUV vacuum chamber in which EUV light is generated, and a hole for guiding the generated EUV light to an external exposure machine (not shown). and blocking the vacuum chamber for blocking the flow, CO ₂ which was a laser gas flow type flow absorbing gas light SPF, the CO ₂ laser beam to be mixed in the generated EUV light is removed by SPF EUV light The quality is improved and supplied to the exposure machine.

  The EUV light source device includes a target supply device 5 that supplies a target 4 to a predetermined condensing point 9 position in the EUV vacuum chamber 1, a driver laser device 6 provided outside the EUV vacuum chamber 1, and an EUV vacuum chamber 1. An incident window 34 for introducing the excitation laser light 7 into the light source, an excitation laser condensing optical system 8 for guiding and condensing the excitation laser light 7 to the position of the condensing point 9, and EUV emitted from the condensing point 9 An EUV condensing optical system that condenses the light 10, a gas curtain device 45 that forms a gas that absorbs an excitation laser in a curtain shape, a first vacuum pump 12 that exhausts the EUV vacuum chamber 1, and a vacuum chamber for blocking And a second vacuum pump 25 for evacuating 2.

  The excitation laser condensing optical system 8 includes at least one lens and / or at least one mirror disposed outside and / or inside the EUV vacuum chamber 1, and is excited laser light emitted from the driver laser device 6. 7 is guided and condensed at the condensing point 9 position. The EUV condensing optical system is an optical system including an EUV condensing mirror 11 and the like, and EUV light 10 radiated from plasma generated by irradiating the target 4 with the excitation laser light 7 at the condensing point 9. The light is reflected and condensed toward an intermediate condensing point (IF) 37. The EUV collector mirror 11 is formed with a molybdenum-silicon (Mo / Si) multilayer film on the reflection surface, and selectively reflects EUV light having a wavelength of around 13.4 nm.

The gas curtain device 45 disposed in front of the blocking vacuum chamber 2 in the EUV optical path in the EUV vacuum chamber 1 includes a gas nozzle 43 for supplying SF ₆ gas and a gas exhaust nozzle 47 disposed to face the gas nozzle 43. The gas curtain of SF ₆ is generated in the EUV optical path by suction with a vacuum exhaust pump (not shown). The gas curtain of SF ₆ absorbs the light of the CO ₂ laser out of the light condensed toward the IF 37 and blocks it from entering the exposure machine.

SF ₆ gas strongly absorbs CO ₂ laser light having a wavelength of 10.6 μm. In addition, SF ₆ gas has a property that the absorption rate is large for weak light and the collection rate is small for strong light.
FIG. 2 is a graph showing the relationship between the light intensity and transmittance of the CO ₂ laser beam that has passed through SF ₆ . Graph for when a 1cm thick fraction of gas and 760Torr by the SF ₆ gas is mixed with nitrogen gas CO ₂ laser beam is transmitted, the partial pressure of the transmittance SF ₆ gas to the incident intensity of the CO ₂ laser beam Is plotted using as a parameter. From the graph, it can be seen that the light absorptance decreases and the transmittance increases as the gas concentration decreases, but the transmittance increases as the incident light intensity increases.

Thus, SF ₆ gas has a non-linear absorption rate with respect to the CO ₂ laser beam, and the absorption rate is high when the energy intensity of the incident light is low, and the absorption rate decreases when the energy intensity of the incident light is high. When SF ₆ gas is used as a gas absorption type SPF, the CO ₂ laser that has a very high energy density intensity of the light that excites EUV plasma has little absorption in the condensing part of the CO ₂ laser, but is scattered or reflected by the target or EUV plasma. _{The two-} laser light has low energy density and can effectively absorb them. Therefore, it is possible to efficiently absorb and block the CO ₂ laser light reflected and scattered by the target while maintaining the energy for exciting the Sn plasma.

The gas nozzle 43 is preferably formed as a supersonic nozzle designed to inject SF ₆ gas at supersonic speed in the EUV vacuum chamber 1. Since the gas flow supplied from the supersonic nozzle is almost sucked by the gas exhaust nozzle 47 before spreading, the SF ₆ gas hardly diffuses into the EUV vacuum chamber 1.

When the SF ₆ gas concentration in the EUV vacuum chamber 1 is increased, the CO ₂ laser light is absorbed, the plasma efficiency of the target 4 is lowered, and the output of the EUV light source device is lowered. Therefore, the EUV light source apparatus of FIG. 1 further includes a hood 49 that wraps the CO ₂ laser light between the incident window 34 and the condensing point 9, and a purge nozzle 51 that supplies a purge gas such as argon (Ar) into the hood. In addition, the SF ₆ gas in the optical path through which the strong CO ₂ laser beam before irradiating the target passes can be removed or diluted with a purge gas. Since the CO ₂ laser light applied to the target 4 is strong and the SF ₆ gas in the optical path is diluted with the purge gas, the CO ₂ laser light can leave a sufficient light intensity for the plasma conversion of the target 4.

The target supply device 5 heats and dissolves solid tin (Sn) and supplies it as a solid or droplet droplet into the EUV vacuum chamber 1 to obtain a target 4. The target 4 passes through the converging point 9 where the excitation laser 7 converges.
The excitation laser beam 7 of the high-power CO ₂ pulse laser (20 kW, pulse repetition frequency 100 kHz, pulse width 20 ns) emitted from the driver laser device 6 is incident on the excitation laser focusing optical system 8 and the incident window 34 of the EUV vacuum chamber 1. Then, the light is condensed at a condensing point 9 that overlaps the trajectory of the droplet target, and the target 4 is excited and turned into plasma to emit various rays 10 including EUV light (center wavelength 13.5 nm).

The radiation beam 10 including the EUV light generated in the target plasma is focused on an intermediate focus (IF) 37 by an EUV mirror 11 having an elliptical surface. A part of the CO ₂ laser light irradiated to the target 4 as the excitation laser light 7 is reflected by the target 4 or reflected / scattered by the plasma generated at the condensing point 9 and enters the EUV mirror 11. The light is reflected and collected by the EUV mirror and travels to the IF 37 together with the EUV light. The IF 37 is disposed in the blocking vacuum chamber 2. The radiation beam 10 condensed toward the IF 37 absorbs the CO ₂ laser beam with the SF ₆ gas while passing through the gas curtain device 45 and increases the purity of the EUV light, and the first pinhole aperture 14 and the second Through the pinhole aperture 23 to the exposure machine (not shown).

  The EUV light source device includes an SPF, an EUV collector mirror, a laser focusing lens / mirror, a laser beam incident window, an EUV sensor, and an optical sensor in the vacuum chamber 1 from debris scattered from the Sn plasma at the focusing point 9. A mitigation device 16 may be provided to protect optical elements such as the entrance window. The mitigation device 16 can be configured, for example, by generating a magnetic force line 20 so as to surround the plasma by a superconducting coil electromagnet 19. Since Sn ions generated in the target plasma have electric charges, they receive Lorentz force in the magnetic field, and are discharged out of the EUV vacuum chamber 1 by the first vacuum pump 12 before being bound by the magnetic lines 20 and scattered around.

On the other hand, since neutral Sn particles other than ions generated in the target plasma are not constrained by the magnetic field, they are scattered as the Sn debris outside the lines of magnetic force, gradually contaminating the optical element or entering the exposure machine. Or cause disability. A blocking vacuum chamber 2 is provided in order to prevent debris from entering the exposure machine.
The blocking vacuum chamber 2 includes a first pinhole aperture (opening) 14 provided in a partition wall with the EUV vacuum chamber 1 and a second pinhole aperture (opening) provided in a wall on the exposure apparatus side. 23 is a space between 23.

  The first pinhole aperture 14 connects the EUV vacuum chamber 1 and the blocking vacuum chamber 2, and the second pinhole aperture 23 guides EUV light incident from the first pinhole aperture 14 to the exposure machine. To do. The hole diameter of the pinhole apertures 14 and 23 is about several mm. The blocking vacuum chamber 2 sandwiched between the two pinhole apertures 14 and 23 is set to a higher vacuum than the space connected to the EUV vacuum chamber 1 and the exposure machine using the second vacuum pump 25.

  Then, the first pinhole aperture 14 is spatially limited to reduce the probability that debris generated in the EUV vacuum chamber 1 will pass through the first pinhole aperture 14, and the first pinhole aperture 14 Since the debris that has passed is collected by the second vacuum pump 25 after passing, substantially no debris flows into the exposure machine through the second pinhole aperture 23. In this way, the target fuel or debris in the EUV vacuum chamber 1 is prevented from flowing into the exposure device based on the principle of differential pumping without using a physical diaphragm that attenuates transmitted light. be able to.

The mitigation device 16 using the magnetic field effectively prevents scratches and dirt on the surface of the optical element due to Sn ions, but does not affect neutral Sn debris. Therefore, the surfaces of optical elements such as the SPF, EUV collector mirror, laser focusing lens / mirror, laser beam incident window, EUV sensor, and incident window accommodated in the EUV vacuum chamber 1 are gradually contaminated with debris. For this reason, the CO ₂ laser reflectivity of an optical element or the like gradually decreases with operation, and light may be absorbed to increase the temperature.

Therefore, for example, by observing the temperature distribution of the optical element with a thermo viewer (not shown), when detecting that the temperature rise of the optical element has increased with the adhesion of neutral Sn debris, The optical element may be stopped and the EUV vacuum chamber 1 may be cleaned.
For this reason, a valve (not shown) for introducing an etchant gas and a gate valve 28 can be provided. The gate valve 28 is provided between the second pinhole aperture 23 and the exposure machine, and prevents the etchant gas from flowing into the exposure machine during cleaning.

Etchant gas may be hydrogen gas, halogen gas, hydrogen halide, argon gas or a mixed gas thereof, and cleaning may be promoted by heating a specific optical element such as SPF with a heating device (not shown). Further, the etchant gas can be excited and promoted by RF or microwave.
For cleaning the optical element, the operation of the EUV light source device is temporarily stopped, the gate valve 28 is closed, and the exposure apparatus and the EUV vacuum chamber 1 are isolated, and the optical element is cleaned with the etchant gas. When the cleaning is completed, the supply of the etchant gas is stopped, the vacuum chamber 25 is evacuated by the vacuum pump 25, and it is confirmed that the degree of vacuum is sufficiently low. Driving can be resumed.

In this embodiment, SF ₆ gas and Ar gas are exhausted by three vacuum exhaust pumps, but the gas concentration in the vacuum chamber 1 needs to be maintained at a concentration that can sufficiently transmit EUV light, for example, 1 Torr or less. It is.
Note that the CO ₂ laser light transmittance of the gas curtain in this embodiment can be easily adjusted by the partial pressure of SF ₆ gas to be supplied, the temperature, and the laser transmission distance.
Further, the gas curtain is not affected by debris accumulation or temperature, and operates stably as an SPF for a long period of time.

(Embodiment 2)
FIG. 3 is a diagram showing a configuration of an EUV light source apparatus according to the second embodiment of the present invention. The EUV light source apparatus according to the present embodiment is an EUV light source apparatus that generates a radiation beam including EUV light by irradiating a target material with CO ₂ laser light, and performs wavelength selection using a grating-type SPF. Using the same SF ₆ gas curtain, the CO ₂ laser beam is absorbed and EUV light is purified and output.

  In the EUV light source apparatus according to the second embodiment, a grating type SPF 61 is provided in the optical path in the middle of condensing the radiation beam 10 containing the EUV light generated in the EUV vacuum chamber 1 onto the IF 37 by the EUV collector mirror 11. Thus, unnecessary light in the radiation beam 10 is eliminated to obtain high-purity EUV light, which is supplied to the exposure machine in the next step through the thin film filter type SPF 38.

In the EUV light source apparatus according to this embodiment, the gas curtain device 45 is disposed at an arbitrary position in the optical path of the EUV light from the condenser mirror 11 to the thin film filter type SPF 38. In FIG. 3, the gas curtain device 45 is configured by disposing a gas nozzle 43 for supplying SF ₆ gas and a gas exhaust nozzle 47 disposed to face the gas nozzle 43 between the grating type SPF 61 and the thin film filter type SPF 38. Is done. The gas curtain device 45 generates an SF ₆ gas curtain so as to cross the EUV light.
The gas curtain of SF ₆ absorbs the CO ₂ laser light from the radiation beam that is about to be emitted toward the exposure machine, and supplies it to the exposure machine as high-purity EUV light.

Further, a hood 49 is provided between the incident window 34 for introducing the excitation laser beam 7 into the EUV vacuum chamber 1 and the condensing point 9 where the trajectory of the target 4 and the optical path of the excitation laser beam 7 intersect. . Purge gas is supplied to the hood 49 from the purge nozzle 51. Since the SF ₆ gas is diluted in the hood 49, the CO ₂ laser light passing through the hood 49 hits the target 4 without being attenuated and can be efficiently converted into plasma.
Similarly to the first embodiment, the EUV light source apparatus according to the second embodiment can remove unnecessary CO ₂ laser light and supply high-purity EUV light.

  By applying the present invention to an extreme ultraviolet light source device used as a light source of an exposure apparatus, high-purity EUV can be obtained, and the life of a spectrum purification filter for that purpose can be extended.

It is a block diagram of the extreme ultraviolet light source device which concerns on the 1st embodiment of this invention. It is a graph which shows the carbon dioxide laser beam transmission characteristic of sulfur hexafluoride. It is a block diagram of the extreme ultraviolet light source device which concerns on the 2nd embodiment of this invention. It is a block diagram of the conventional extreme ultraviolet light source device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... EUV vacuum chamber, 2 ... Blocking vacuum chamber, 4 ... Target, 5 ... Target injection apparatus, 6 ... Driver laser, 7 ... Excitation laser beam, 8 ... Laser focusing optical system, 9 ... focusing point, 10 ... EUV light, 11 ... EUV focusing mirror, 12 ... first vacuum pump, 14 ... first pinhole aperture , 16 ... Mitigation device, 19 ... Superconducting coil electromagnet, 20 ... Magnetic field lines, 23 ... Second pinhole aperture, 25 ... Second vacuum pump, 28 ... Gate valve, 34 ... Incident window, 37 ... Intermediate focusing point (IF), 38 ... Thin film filter type SPF, 43 ... Gas nozzle, 45 ... Gas curtain device, 47 ... Exhaust nozzle, 49 ... Food, 51 ... Par Nozzle, 61 ... grating type SPF.

Claims (4)

A target supply device for supplying a target material into the vacuum chamber;
A laser beam inlet for introducing a carbon dioxide laser beam;
An excitation laser condensing optical system that emits radiation light including extreme ultraviolet (EUV) light by irradiating the target material supplied from the target supply device with the carbon dioxide laser light incident from the laser inlet, and generating plasma;
An EUV condensing optical system that condenses the radiated light including the EUV light at an intermediate condensing point (IF);
A spectral purification filter (SPF) that selects the EUV light from the emitted light and supplies it to an external device;
A gas passage having a slit nozzle and a gas sink facing the slit nozzle to form a gas curtain in the optical path of the emitted light;
An extreme ultraviolet light source device for reducing the carbon dioxide laser light and increasing the purity of the extreme ultraviolet light by flowing a gas that absorbs the carbon dioxide laser light through the gas passage. The extreme ultraviolet light source device according to claim 1, wherein the gas that absorbs the carbon dioxide laser beam contains sulfur hexafluoride (SF ₆ ).   The extreme ultraviolet light source device according to claim 1, wherein the slit nozzle ejects a gas that absorbs the carbon dioxide laser beam at a supersonic speed.   A nozzle for supplying a buffer gas in the optical path of the excitation laser condensing optical system; and the gas that absorbs the carbon dioxide laser light in the optical path of the excitation laser condensing optical system is excluded by the buffer gas. The extreme ultraviolet light source device according to any one of claims 1 to 3.