JP2007019286A - Extreme ultraviolet light optical source and method of removing deposits on extreme ultraviolet optical source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a stable EUV by efficiently removing impurities (e.g., deposits of Sn and/or Sn compound, etc.) deposited to electrodes, etc. in an EUV light source. <P>SOLUTION: A raw material gas such as SnH<SB>4</SB>is introduced into a chamber 1, a high voltage pulse is applied between electrodes 3a, 3b from a high voltage pulse generator 12 to drive a high density high temperature plasma generator 9 to generate a high density high temperature plasma, thereby radiating an EUV light of 13.5 nm in wavelength. An EUV collecting mirror 5 reflects the radiated EUV light to radiate from an EUV light output unit 6. At the EUV radiation stop, etc. A rare gas such as Xe is introduced into the chamber 1, and a high voltage pulse is applied between the electrodes 3a, 3b from the high voltage pulse generator 12 to generate a rare gas plasma discharge. The rare gas high density high temperature plasma adiabatically expands to produce high speed ions or neutral atoms of the rare gas which collide against impurities deposited to the electrodes, etc. in the chamber to thereby break the impurities away. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an extreme ultraviolet light source device that emits extreme ultraviolet light and a deposit removal method for removing deposits accumulated in a container in an extreme ultraviolet light source device.

With the miniaturization and high integration of semiconductor integrated circuits, improvement in resolving power is demanded in the projection exposure apparatus for production. In order to meet the demand, the exposure light source has been shortened, and as a next-generation semiconductor exposure light source following the excimer laser device, extreme ultraviolet light (hereinafter referred to as EUV (hereinafter referred to as EUV)) having a wavelength of 13 to 14 nm, particularly 13.5 nm. Extreme ultraviolet light source devices (hereinafter also referred to as EUV light source devices) that emit light (also referred to as Extreme Ultra Violet) light have been developed.
Several methods for generating EUV light in an EUV light source device are known. One of them is to generate a high-density and high-temperature plasma by heating and excitation of EUV radiation species, and to generate EUV light emitted from this plasma. There is a way to take it out.
The EUV light source device adopting such a method is an LPP (Laser Produced Plasma) type EUV light source device and a DPP (Discharge Produced Plasma) type EUV light source device according to a high-density and high-temperature plasma generation method. (See Non-Patent Document 1, for example).

The LPP EUV light source device uses EUV radiation from high-density and high-temperature plasma generated by irradiating a target such as a solid, liquid, or gas with a pulse laser.
On the other hand, the DPP EUV light source device uses EUV radiation from high-density and high-temperature plasma generated by current driving.
As described in Non-Patent Document 1, there are a Z-pinch method, a capillary discharge method, a plasma focus method, a hollow cathode trigger Z-pinch method, etc. as discharge methods in the DPP EUV light source. Compared with the LPP EUV light source, the DPP EUV light source has advantages such as downsizing of the light source device and low power consumption of the light source system, and high expectations for practical use.
In both types of EUV light source devices described above, as a radioactive species that emits EUV light having a wavelength of 13.5 nm, that is, as a raw material for high-density and high-temperature plasma, currently about 10-valent Xe (xenon) ions and Sn (tin) ions are present. It is considered promising.

Here, Sn has a conversion efficiency which is a ratio of the EUV light radiation intensity with a wavelength of 13.5 nm to the input energy for generating high-density and high-temperature plasma several times larger than Xe. For this reason, Sn is attracting attention as an EUV radiation species.
When Sn is used as the EUV radiation species, Sn has a low vapor pressure and does not reach a sufficient vapor pressure unless it exceeds 2000 ° C. Therefore, Sn is supplied to the plasma generation region by evaporation or discharge by laser irradiation of Sn. This was done by self-heating of the Sn supply source.
However, unlike Xe, which is in a gas state at normal temperature, Sn is solid at normal temperature, and there is a problem that a large amount of debris due to Sn is generated when heated and excited to generate high-density high-temperature plasma. Further, Sn having a low vapor pressure is deposited in a low temperature part in the apparatus when the plasma state returns to the normal gas state, and the apparatus performance deteriorates.

In order to improve such a problem, as described in Patent Document 1, a method of supplying a stannane (SnH ₄ ) gas to a plasma generation region has been proposed. Advantages of this method include the following points.
(i) Unlike the method of evaporating solid Sn at room temperature, heating to a high temperature is not necessary.
(ii) SnH ₄ that is a gas is easily transported to a heating / excitation space (high-density high-temperature plasma generation space) that is a plasma generation region.
(iii) Mixing with a rare gas makes it easy to control the Sn concentration.
(iv) Unlike solid Sn, since it is a normal gas, it is easy to be discharged in an atomic gas state after plasma formation in a high-density and high-temperature plasma generation space, and it is difficult to agglomerate and deposit in a low-temperature part in the apparatus.

FIG. 26 shows a configuration example of a DPP EUV light source device.
As shown in FIG. 26, the DPP EUV light source apparatus has a chamber 1 that is a discharge vessel. In the chamber 1, for example, a ring-shaped first main discharge electrode (cathode) 3a and a second main discharge electrode (anode) 3b are arranged with a ring-shaped insulating material 3c interposed therebetween. The first main discharge electrode 3a and the second main discharge electrode 3b are made of a refractory metal such as tungsten, molybdenum, or tantalum. The insulating material 3c is made of, for example, silicon nitride, aluminum nitride, diamond, or the like.
The chamber 1 includes a first container 1a on the first main discharge electrode side made of a conductive material and a second container 1b on the second main discharge electrode side made of the same conductive material. . The first container 1a and the second container 1b are separated and insulated by the insulating material 3c. Here, the second container 1b and the second main discharge electrode 3b of the chamber 1 are grounded.

The ring-shaped first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c are arranged so that the respective through holes are positioned substantially on the same axis, thereby forming a communication hole. When electric power is supplied between the first main discharge electrode 3a and the second main discharge electrode 3b to generate a discharge, high-density and high-temperature plasma is generated in the communication hole or in the vicinity of the communication hole.
That is, the high-density and high-temperature plasma generator 9 is located in or near the space surrounded by the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c. The power supply between the first main discharge electrode 3a and the second main discharge electrode 3b is performed by the high voltage pulse generator 12 connected to the first main discharge electrode 3a and the second main discharge electrode 3b. The
The first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c constitute a DPP type EUV generation unit. The DPP type EUV light source apparatus has various configuration examples other than those shown in FIG. 26. Refer to Non-Patent Document 1 for this.

On the first container 1 a side of the chamber 1, a gas inlet 2 connected to a gas supply unit 11 that supplies a source gas that is an EUV radiation species is provided. The source gas is supplied to the high voltage high temperature plasma generation unit 9 in the chamber 1 through the gas inlet 2.
A pressure monitor 15 is provided on the second container 1b side of the chamber 1 to monitor the pressure in the chamber (high-density high-temperature plasma generation unit pressure). Further, an exhaust unit 13 for adjusting the pressure of the high-density and high-temperature plasma generation unit 9 and exhausting the interior of the chamber 1 is connected to a gas exhaust port 7 provided on the second container 1b side of the chamber. .
An EUV collector mirror 5 is provided in the second container 1b of the chamber. The EUV collector mirror 5 includes, for example, a plurality of spheroids having different diameters or mirrors having a paraboloid shape. These mirrors are arranged on the same axis with the rotation center axes overlapped so that the focal positions substantially coincide. This mirror is formed by, for example, densely coating a metal such as ruthenium (Ru), molybdenum (Mo), and rhodium (Rh) on the reflective surface side of a base material having a smooth surface made of nickel (Ni) or the like. The EUV light having an oblique incident angle of 0 ° to 25 ° can be favorably reflected.

In addition, between the high-density high-temperature plasma and the EUV collector mirror 5, metal particles (for example, discharge electrodes) in contact with the high-density high-temperature plasma are sputtered by the plasma to generate debris such as metal powder, Sn, etc. A debris trap 4 for capturing debris and the like caused by radioactive species and allowing only EUV light to pass through is installed.
As described in Patent Document 2, for example, the debris trap 4 is composed of a plurality of plates installed in the radial direction of the high-density and high-temperature plasma generation region.
The DPP EUV light source device shown in FIG. The control unit 14 controls the high voltage pulse generation unit 12, the gas supply unit 11, and the gas exhaust unit 13 based on an EUV emission command from the control unit 40 of the exposure machine.
For example, when receiving an EUV light emission command from the control unit 40 of the exposure machine, the control unit 14 controls the gas supply unit 11 to supply the source gas to the high-density and high-temperature plasma generation unit 9 in the chamber 1. Further, based on the pressure data from the pressure monitor 15, the source gas supply amount from the gas supply unit 11 is controlled so that the high-density and high-temperature plasma generator 9 in the chamber 1 has a predetermined pressure, and the gas exhaust unit 13. Controls the amount of exhaust. Thereafter, in order to generate high-density and high-temperature plasma that emits EUV, the high-voltage pulse generator 12 is controlled to supply power between the first main discharge electrode 3a and the second main discharge electrode 3b.

The EUV light is emitted as follows.
A discharge gas is introduced into the chamber 1 which is a discharge vessel from a gas supply unit 11 through a gas introduction port 2 provided on the first vessel 1a side.
The discharge gas is a raw material gas for efficiently forming a radiation species that emits EUV light having a wavelength of 13.5 nm in the high-density and high-temperature plasma generation unit 9, and is, for example, SnH ₄ (Stannane). The introduced SnH ₄ flows in the chamber 1 and reaches the gas outlet 7 provided on the second container 1b side. A gas exhaust unit 13 having gas exhaust means (not shown) such as a vacuum pump is connected to the gas exhaust port 7. That is, the discharge gas that has reached the gas discharge port 13 is exhausted by the gas exhaust means provided in the gas exhaust unit 13.

Here, the pressure of the high-density and high-temperature plasma generation unit 9 is adjusted to 1 to 20 Pa. This pressure adjustment is performed as follows, for example. First, the control unit 14 receives pressure data output from the pressure monitor 15 provided in the chamber 1. Based on the received pressure data, the control unit 14 controls the gas supply unit 11 and the gas exhaust unit 13 to adjust the supply amount and exhaust amount of SnH ₄ into the chamber 1, so that the high-density and high-temperature plasma generation unit The pressure of 9 is adjusted to a predetermined pressure.
Between the second container 1b and the second main discharge electrode 3b, which are grounded as described above, and the first container 1a and the first main discharge electrode 3a, from the high voltage pulse generator 12 A high voltage pulse voltage of approximately +20 kV to −20 kV is applied. As a result, creeping discharge is generated on the surface of the insulating material 3c, and the first main discharge electrode 3a and the second main discharge electrode 3b are substantially short-circuited, and the first main discharge electrode 3a, A large pulsed current flows between the second main discharge electrodes 3b.

Thereafter, high-density and high-temperature plasma is generated in the high-density and high-temperature plasma generator 9 between the ring-shaped first and second main discharge electrodes 3a and 3b by Joule heating due to the pinch effect. 5 nm EUV light is emitted.
The emitted EUV light is reflected by the EUV collector mirror 5 provided on the second main discharge electrode 3b side, and the illustration is omitted from the EUV light extraction unit 6 including the wavelength selection means 8 (for example, an optical filter). The light is emitted to an irradiation unit which is an exposure machine side optical system.
The wavelength selection means selects, for example, EUV light having a wavelength of 13.5 nm. That is, for example, EUV light having a wavelength of 13.5 nm selected by the wavelength selection unit is emitted toward the exposure apparatus side optical system.
JP 2004-279246 A JP-T-2002-504746 Japanese National Patent Publication No. 10-512092 JP 2003-218025 A “Current Status and Future Prospects of EUV (Extreme Ultraviolet) Light Source Research for Lithography” Plasma Fusion Res. Vol. 79. No. 3, P219-260, March 2003

As a result of the inventors' diligent research and experiments, even if stannane (SnH ₄ ) is used as the radioactive species supply material, Sn and / or Sn compounds (for example, carbides, oxides, etc.) are used as EUV light emitting devices. It turned out that it did not deposit at all in the low temperature part.
That is, SnH ₄ that did not contribute to plasma formation among SnH ₄ and / or SnH ₄ recombined with fragments such as Sn, SnH, SnH ₂ , SnH ₃ (hereinafter referred to as SnH _x ) generated by the plasma, and fragments with high vapor pressure SnH _x is discharged as a gas as it is by the exhaust means spatially connected to the plasma generation region of the EUV light source device. However, as a result of plasma formation, some of the metal clusters such as Sn and Sn _X of the atomic gas that decomposes and fragments, such as fragments SnH _x generated by the plasma, come into contact with the low temperature part of the apparatus, and Sn and / or Sn It was found that the compound was deposited. For example, SnH ₄ decomposes on a metal surface at about 150 ° C. to make a tin mirror.
In addition, the Sn compound as used in the field of this invention is Sn carbide, an oxide, etc., for example. In addition to introducing SnH ₄ into the plasma generation region as a method for supplying Sn, which is an EUV radiation species, the same problem occurs when other high vapor pressure Sn hydrides such as Sn ₂ H ₆ are used. Needless to say.

For example, when SnH ₄ is used as a discharge gas, the deposition of Sn and / or Sn compounds occurs at the following times.
(i) In order to temporarily stop the exposure process, the power supply from the high voltage pulse generator 12 to the first main discharge electrode 3a and the second main discharge electrode 3b is cut off to stop the discharge. When the high-density plasma generation is suspended.
When the discharge is stopped, the temperature of the EUV light source device, particularly the first main discharge electrode 3a and the second main discharge electrode 3b, decreases. A part of the metal cluster, the fragment SnH _{x and the} like that have floated come into contact with the portion where the temperature has decreased, and Sn and / or Sn compounds are deposited.
(ii) Plasma discharge is occurring.
During the discharge, the temperature of the first main discharge electrode 3a and the second main discharge electrode 3b does not become low. However, during discharge, adhesion of the metal clusters decomposed and generated as a result of plasma formation, fragments SnH _{x and the} like generated by plasma, and detachment that the plasma scrapes occur simultaneously. Therefore, when a situation occurs in which the amount of adhesion is greater than the separation, deposits are generated.

In particular, as shown in FIG. 27, when Sn and / or Sn compounds are deposited on the surfaces of the first main discharge electrode 3a (cathode), the second main discharge electrode 3b (anode), and the insulating material 3c, The diameter of the ring-shaped high-density and high-temperature plasma generation unit 9 that is a space surrounded by the main discharge electrode 3a, the second main-discharge electrode 3b, and the insulating material 3c becomes narrower, or the space of the high-density and high-temperature plasma generation unit 9 The shape becomes uneven. As a result, the plasma discharge becomes unstable, or the high-density and high-temperature plasma itself becomes difficult to be generated due to the conduction between the two electrodes due to the deposition of the insulating portion.
For this reason, the pulse-to-pulse energy stability of EUV light emitted from high-density high-temperature plasma and EUV light emission position stability become unstable. That is, the characteristics of the EUV light emitted from the EUV generation light source device become unstable.
The present invention has been made to solve the above problems, and efficiently removes impurities (for example, deposits of Sn and / or Sn compounds, etc.) deposited on the inside of an EUV light source device, particularly on electrodes and the like. Thus, the object is to obtain a stable EUV.

In order to solve the above problems, in the present invention, in the EUV light source apparatus, in addition to a supply means for supplying a raw material containing EUV radiation species into a container in which EUV is generated, a rare gas supply for supplying a rare gas into the container is provided. And a switching means for switching supply from both supply means.
In the EUV light source device having the above-described configuration, for example, when EUV light is not generated, the raw material containing the EUV radiation species into the container is switched to supply rare gas by the switching means. Then, a rare gas plasma is started in the container, and impurities (for example, deposits such as Sn and / or Sn compound) deposited on the inside of the EUV light source device, particularly on the electrodes, are removed by the rare gas plasma.
Hereinafter, removal of impurities (for example, deposits of Sn and / or Sn compounds, etc.) deposited on the inside of the EUV light source device, particularly on the electrodes, may be referred to as “cleaning”.

Cleaning of the electrodes and the like inside the EUV light source device uses an action of causing high-speed ions or neutral atoms of a rare gas to collide with the contaminated surface and causing the contaminant to jump out of the contaminated surface.
The fast ions or neutral atoms are generated from a rare gas plasma generated by the same procedure as that for generating a high-density high-temperature plasma that emits EUV light. That is, the second container and the second main discharge electrode, which are supplied with the rare gas from the rare gas supply means and are grounded in the container in which EUV is generated, and the first container and the first main discharge electrode are grounded. The high voltage pulse voltage is applied from the high voltage pulse generator.
As a result, creeping discharge is generated on the surface of the insulating material, and the first main discharge electrode and the second main discharge electrode are substantially short-circuited, and the first main discharge electrode and the second main discharge electrode are short-circuited. A large pulse current flows between the discharge electrodes.

A rare gas plasma generated by a discharge having a sufficiently large dI / dt, which is the rise of the discharge current, generates a high-temperature, high-density pinch plasma on the central axis due to a pinch effect that is radially contracted by a magnetic field generated by the discharge current. Generate. This pinch plasma is in an electrically neutral state and is composed of neutral atoms, ions, and electrons.
As the discharge current falls, that is, the discharge current value decreases, the self-magnetic field of the discharge current attenuates. For this reason, the force for contracting the plasma is reduced, and it is gradually difficult to maintain the pinch plasma, and the pinch plasma adiabatically expands in the direction of the solid angle 4π. That is, the pinch plasma collapses, and ions and neutral atoms are scattered at high speeds in all directions. For example, when the rare gas is Xe, the speed of Xe ions scattered at a high speed may be several thousand m / s or more. High-speed ions are neutralized as they move away from the plasma by colliding with neutral atoms for charge exchange or recombining with electrons when they move through the gas.
When these high-speed ions or neutral atoms collide with impurities deposited on the surfaces of the first and second main discharge electrodes, the insulating material, the EUV collector mirror, the first and second containers, the high-speed ions or The elastic collision between the neutral atom and the impurity atom gives high-speed ions or kinetic energy of the neutral atom to the impurity atom, and the impurity atom jumps into the gas to remove the impurity.

Here, consider the case of applying a sputtering apparatus for generating a film on a general substrate. In this case, ions irradiated from an ion source or the like generally have low kinetic energy. Therefore, the kinetic energy given to the atoms on the impurity surface deposited on the first and second main discharge electrodes and the like by the elastic collision is small, and the atoms cannot jump out from the impurity surface. For this reason, in order to give ions sufficient kinetic energy for ejecting atoms from the impurity surface, it is necessary to accelerate the ions by applying a bias having a polarity opposite to that of the ions to the impurities.
Even in the case of general film formation, a high DC voltage is applied between the substrate and the target (material to be deposited), and ions are collided with the target so that the repelled target material is deposited on the substrate. Yes. That is, it is difficult to blow off the target material unless a DC high voltage is applied.
On the other hand, in this cleaning with ions or neutral atoms from the pinch plasma, since the ions or neutral atoms themselves have high kinetic energy, it is not necessary to apply a bias to the cleaning target.
Here, when performing cleaning using the adiabatic expansion of the pinch plasma described above, it is not always necessary to use a rare gas as a plasma raw material to be introduced into the container. However, for the reason that it is easy to adhere to each part in the container to be cleaned and there is no reactivity with each part in the container, it is most preferable to use a rare gas as the cleaning plasma raw material. It is valid.

  In the present invention, cleaning is performed by causing high-speed ions or neutral atoms generated by adiabatic expansion of high-density high-temperature plasma to collide with impurities and releasing the impurities. High-density and high-temperature plasma can be generated by any of the Z-pinch method, capillary discharge method, plasma focus method, hollow cathode trigger Z-pinch method, etc., and cleaning is possible by adiabatic expansion of the generated high-density and high-temperature plasma. Become. That is, in the DPP type EUV light source device, it is possible to implement the present invention regardless of the plasma generation method.

Based on the knowledge described above, the present invention solves the above-described problems as follows.
(1) A container in which high-density and high-temperature plasma is generated, a raw material supply means for supplying a raw material containing an extreme ultraviolet light emitting species and / or a compound of an extreme ultraviolet light emitting species into the container, and the supply in the container Pre-ionization means for pre-ionizing the raw material, heating / excitation means for heating and exciting the pre-ionized raw material in the container to generate high-density high-temperature plasma, and extreme ultraviolet light emitted from the high-density high-temperature plasma. In an extreme ultraviolet light source device having a condensing optical means for condensing and an extreme ultraviolet light extraction unit for extracting extreme ultraviolet light through the condensing optical means, a rare gas supply means for introducing a rare gas, and the container There is provided a switching means for switching between a raw material supply from the raw material supply means and a rare gas supply from the rare gas supply means, and generates a rare gas plasma in the container to add the raw material. · Removing deposits deposited in the container when excited to generate high density and high temperature plasma.
(2) In the above (1), the raw material supply flow path from the raw material supply means and the rare gas supply flow path from the rare gas supply means are connected to each other in the container independently of each other.
(3) In the above (1) and (2), the container is provided with a light shielding means for shielding the extreme ultraviolet light emitted from the high-density and high-temperature plasma from being output to the outside.
(4) In the above (3), the light shielding means includes a first space in which the raw material is heated and excited to generate a high-density and high-temperature plasma when extreme ultraviolet light is shielded, and the condensing optical means. It is provided so as to be divided into the included second space.
(5) In the above (1) to (4), there is provided a control means for controlling the operation of the raw material supply means, the preionization means and the drive power source for the heating excitation means, the rare gas supply means, and the switching means.
(6) In the above (1) to (5), the extreme ultraviolet light emitting species is either tin (Sn) or lithium (Li).
(7) In the above (1) to (5), the raw material is stannane (SnH ₄ ).
(8) In the above (1) to (7), the rare gas is xenon (Xe).
(9) In the above (1) to (8), a hydrogen gas supply means is further provided, and the switching means supplies the raw material supplied from the raw material supply means into the container and supplies the rare gas from the rare gas supply means. When the rare gas is supplied into the container by switching to, the hydrogen gas is switched to be supplied from the hydrogen gas supply means into the container together with the rare gas.
(10) Extreme ultraviolet light emitted from a high-density and high-temperature plasma generated by heating and exciting a raw material containing an extreme ultraviolet light emitting species and / or a compound of an extreme ultraviolet light emitting species in a container. In the deposit removal method for removing deposits in a container in an ultraviolet light source device, while the generation of extreme ultraviolet light is suspended, the raw material supply into the container is switched to the rare gas supply, and the rare gas is supplied. A rare gas plasma discharge is generated in the container, and deposits deposited in the container generated when the high-density and high-temperature plasma is generated are removed by the rare gas plasma.
(11) In (10), when the generation of extreme ultraviolet light is suspended, the supply of the raw material into the container is stopped, the inside of the container is evacuated, and then a rare gas is supplied into the container.
(12) In the above (10) and (11), when supplying the rare gas into the container, the inside of the container is heated and excited in order to generate extreme ultraviolet light and condensed. A rare gas plasma discharge is generated in the space where the heating and excitation are performed.
(13) In the above (10) to (12), when switching between the raw material supply from the raw material supply means and the rare gas supply from the rare gas supply means, one supply flow rate is gradually reduced and the other supply Increase the flow rate gradually.
(14) In the above (10) to (13), when the number of occurrences of extreme ultraviolet light reaches a predetermined number, it is determined that the deposit has reached a predetermined amount, and a warning signal is output.
(15) In (10) to (14), the deposit amount of the deposit is calculated by monitoring, and when the calculated deposit amount reaches a predetermined value, it is determined that the deposit has reached a predetermined amount, Output a warning signal.

In the present invention, the following effects can be obtained.
(1) Since a rare gas supply function as a cleaning gas is provided in addition to the EUV radiation source gas supply function, it is possible to generate a plasma discharge of the rare gas. Deposits deposited on the main discharge electrode, the second main discharge electrode, and the insulating material can be removed using, for example, the time during which the EUV light is not emitted when the exposure process is interrupted.
Further, even if the discharge is stopped and the electrode temperature is lowered and impurities are deposited in the low temperature portion of the apparatus, the deposits can be removed by the cleaning operation using the rare gas plasma. For this reason, it becomes possible to remove the deposits in the EUV light source device without reducing the operating time of the exposure apparatus equipped with the EUV generator.
Therefore, destabilization of plasma discharge can be prevented, and conduction between the first main discharge electrode and the second main discharge electrode due to deposition of deposits on the insulating portion can be prevented, and stable EUV can be achieved. Light can be obtained.
(2) Rare gas plasma discharge is performed while flowing a rare gas (Xe gas), and the range in which the rare gas plasma spreads is large. For this reason, depending on the rare gas plasma discharge conditions, not only the first and second electrodes, the insulating material but also the debris trap and the deposit deposited on the EUV collector mirror may be removed by the cleaning operation using the rare gas plasma. Is possible.
(3) The rare gas plasma generation means and the EUV radiation source gas (for example, SnH ₄ ) heating / excitation means can be used in combination. For this reason, it is possible to generate a rare gas plasma discharge only by switching the supply of the source gas of the EUV radiation species to the supply of a rare gas that is a cleaning gas. Separately, a rare gas plasma discharge generating means is provided in the container. The apparatus can be configured compactly.
(4) If the rare gas (for example, Xe gas) discharge is continued even when the generation of EUV is interrupted, the temperature drop amount of the first and second main discharge electrodes is also reduced, The amount of deposited Sn and / or Sn compound is also reduced. For this reason, it becomes possible to shorten the rare gas cleaning process.
(5) When switching the gas supply, the gas flow rate of the rare gas supply channel is gradually increased and the gas flow rate of the source gas supply channel is gradually decreased so that the gas flow rate becomes almost zero. If the path is closed, it becomes easy to control the pressure in the chamber at the time of gas switching (that is, the pressure of the high-density and high-temperature plasma generator).
(6) After the exposure process, after exhausting the raw material gas (SnH ₄ gas) remaining in the chamber including the high-density and high-temperature plasma generation unit, the rare gas (Xe gas) is supplied and the rare gas (Xe gas) discharge is performed. By performing the above, it is possible to prevent the metal mirror (tin mirror) from being formed in the low temperature portion inside the chamber by the residual raw material gas (SnH ₄ gas) during the rare gas (Xe gas) plasma generation. .
(7) Hydrogen (H ₂ ) gas is also supplied as a cleaning gas in addition to a rare gas, and so-called reactive sputtering is performed, whereby not only cleaning is performed by Xe plasma, but also deposits in the container are converted to hydrogen plasma. It can be reacted, gasified and exhausted. For this reason, effective cleaning is possible, and the cleaning time can be shortened.
(8) At the time of the cleaning process using the rare gas plasma, the first space where the first main discharge electrode, the second main discharge electrode, the insulating material and the debris trap are present, and the second space where the EUV collector mirror and the like are present If the cleaning process using the rare gas plasma is performed only in the first space, the first main discharge electrode, the second main discharge electrode, and the insulating material collide with the rare gas (Xe gas) plasma. Impurities that are detached from the material are not reattached to the EUV collector mirror.
For this reason, the reflectivity with respect to 13.5 nm of the EUV collector mirror caused by the reattached impurities does not decrease, and the intensity of EUV light emitted to the outside does not decrease.
(9) Counting the number of times pulsed EUV light is emitted, and when the count reaches a predetermined value, or measuring the film thickness of the deposit deposited in the container, the film thickness reaches the predetermined value. When the cleaning process is required, a warning is displayed on the EUV light source and, for example, the cleaning process is started manually or automatically to remove impurities deposited on the electrodes. This makes it possible to perform the cleaning process efficiently.

Hereinafter, an EUV light source apparatus according to an embodiment of the present invention will be described.
1. First Embodiment (1) Apparatus Configuration FIG. 1 is a diagram showing a configuration of an EUV light source apparatus according to a first embodiment of the present invention. With reference to FIG. 1, an EUV light source apparatus according to the first embodiment of the present invention is shown. The configuration will be described.
The EUV light source apparatus according to the present embodiment has a chamber 1 that is a discharge vessel, similar to that shown in FIG. 26. In the chamber 1, for example, a ring-shaped first main discharge electrode (cathode) 3a and A second main discharge electrode (anode) 3b is disposed with a ring-shaped insulating material 3c interposed therebetween.
The chamber 1 includes a first container 1a on the first main discharge electrode side made of a conductive material and a second container 1b on the second main discharge electrode side made of the same conductive material. . The first container 1a and the second container 1b are separated and insulated by the insulating material 3c, and the second container 1b and the second main discharge electrode 3b of the chamber 1 are grounded.
As described above, the ring-shaped first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c are arranged so that the respective through holes are positioned substantially on the same axis to form communication holes. ing. When electric power is supplied between the first main discharge electrode 3a and the second main discharge electrode 3b by the high voltage pulse generator 12 to generate discharge, high-density and high-temperature plasma is generated in or near the communication hole. Is done.
In addition, the portion that is composed of the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c, and discharges by the pulse power from the high voltage pulse generation unit 12 to generate high density high temperature plasma, In the present invention, this is called heating / excitation means.

A gas inlet 2 connected to a gas supply unit 20 that supplies a source gas (for example, SnH ₄ ) that is an EUV radiation species is provided on the first container 1 a side of the chamber 1.
In the present embodiment, the gas supply unit 20 has a cleaning gas supply function in addition to the EUV radiation source gas supply function shown in FIG.
That is, each gas supply source is provided in the gas supply unit 20 so that both the source gas and the rare gas of the EUV radiation type can be supplied to the high-density and high-temperature plasma generation unit 9.
For example, SnH ₄ (stannane) is used as a source gas for EUV radiation species, and Xe (xenon) is used as a rare gas for cleaning. In that case, the gas supply unit is provided with an SnH ₄ gas supply source 20a and an Xe gas supply source 20b.
Valves V1, V2 and gas flow regulators MFC1, MFC2 are attached to the outlet sides of the gas supply sources 20a, 20b, respectively. As the valves V1 and V2, for example, air operated valves are used. In FIG. 1, an air supply source for opening and closing the air operated valve, an electromagnetic valve for controlling the supply of air from the air supply source, and the like are omitted. As the gas flow rate adjusters MFC1 and MFC2, for example, mass flow controllers are used.

The valve V1 opens and closes the SnH ₄ gas supply path, and the gas flow rate regulator MFC1 adjusts the flow rate. Similarly, the valve V2 opens and closes the Xe gas supply path, and the gas flow rate adjuster MFC2 adjusts the flow rate.
The opening and closing of the valves V1, V2 is controlled by a signal from the control unit 14. When the valves V1 and V2 are air operated valves, the opening and closing of the valves V1 and V2 is controlled by opening and closing an electromagnetic valve for controlling the air supply from the air supply source for opening and closing the air operated valve.
Further, the gas flow rate adjusters MFC1 and MFC2 are controlled by signals from the control unit 14 based on parameters input from the setting unit included in the control unit 14. The setting unit may be provided independently of the control unit 14.
The SnH ₄ gas supply path and the Xe gas supply path are coupled downstream of the flow rate adjusting units MFC1 and MFC2 to form one system supply path, which is connected to the gas inlet 2 provided in the first container of the chamber. Is done.
The cleaning gas may be other rare gas such as Ar or Kr, but not Xe gas, as long as it does not generate debris and can be expected to be plasma sputtering cleaned. If it is equivalent to the above, deposits are effectively removed by elastic collision during cleaning with rare gas plasma.
For example, when the deposit is Sn, since the atomic weight of Sn is 50, it is preferable to use Xe gas having an atomic weight of 54 as the cleaning gas.
Furthermore, when the SnH ₄ gas is diluted with a rare gas or the like and supplied to the high-density and high-temperature plasma generation unit 2, a gas supply path for the dilution gas may be added. In this case, the dilution gas supply path is provided with a valve and a gas flow rate regulator. When the cleaning rare gas is also used for dilution, it is not necessary to provide a new dilution gas supply path.

A pressure monitor 15 is provided on the second container 1b side of the chamber 1 to monitor the pressure in the chamber (high-density and high-temperature plasma generating part pressure). Further, an exhaust unit 13 for adjusting the pressure of the high-density and high-temperature plasma generation unit 9 and exhausting the interior of the chamber 1 is connected to a gas exhaust port 7 provided on the second container 1b side of the chamber. .
Further, as described above, the EUV collector mirror 5 is provided in the second container 1b of the chamber. Between the high-density high-temperature plasma and the EUV collector mirror 5, a metal ( For example, a debris trap 4 is provided for capturing debris such as metal powder generated by sputtering of the discharge electrode) by the plasma or debris caused by a radiation species such as Sn and allowing only EUV light to pass therethrough. .
Further, the EUV light source apparatus according to the present embodiment is provided with a shutter 21 that blocks emission of light such as EUV light to the outside. The shutter 21 is installed between the EUV collector mirror 5 and the EUV light extraction unit 6. The shutter 21 is opened and closed by operating the shutter drive mechanism 21 a based on the control of the shutter drive control unit 16. The shutter drive control unit 16 controls the drive of the shutter drive mechanism 16 based on the opening / closing command from the control unit 14.

By the way, as described above, when EUV light is generated by applying pulse power between the first and second main discharge electrodes 3a and 3b from the high voltage pulse generator 12, the pressure of the high temperature and high density plasma generator 9 is increased. Is adjusted to 1-20 Pa. Under such a low pressure, it is difficult for electric discharge to occur depending on the electrode structure, and as a result, the output of EUV light may become unstable.
In order to generate a stable discharge under conditions where discharge is difficult to occur, it is desirable to perform preionization. In this embodiment, a preionization unit 17 for performing preionization and a preionization power source 18 are provided. .
As the preliminary ionization unit 17, for example, an electron beam generator is used. As an electron beam generator, the electron beam generator described in patent document 3 can be used, for example.
In the electron beam generator constituting the preliminary ionization unit 17, a filament heater 17b and a cathode 17c, which are electron beam sources, are provided in an insulating container 17a made of an insulating member such as glass. A power supply terminal connected to each of the filament heater 17b and the cathode 17c protrudes outside the insulating container 17a. The insulating container 17a is sealed and the inside is kept in a vacuum.
The insulating container 17a is provided with an electron beam transmissive film 17d that transmits the electron beam. The electron beam permeable film 17d is conductive. The electron beam permeable film 17d is directly attached to the first container 1a.

The filament heater 17b is heated by being supplied with a current from a filament power transformer Tr1, which is an insulating transformer connected to an AC power source in the preliminary ionization power source 18. Further, a negative high voltage -HV2 is applied to the cathode 17c from the insulation transformer Tr2 connected to the AC power source 18b via a booster circuit 18a such as a cockcroft circuit. Normally, the electron beam is drawn out by setting the electron beam transmission window 17d to the ground potential, and the electron beam is emitted through the electron beam transmission window 17d as shown by the arrow in FIG.
Here, the second main discharge electrode 3b on the side where the EUV collector mirror 5 or the like is provided is set to the ground potential in order to prevent discharge from occurring between the EUV collector mirror 5 and the like. Therefore, a minus high voltage −HV1 of −several tens kV is applied from the high voltage pulse generator 12 to the first main discharge electrode 3a and the first container 1a. Therefore, the potential of the electron beam transmissive film 17d is also -HV1. Therefore, the negative high voltage −HV2 applied to the cathode 17c of the electron beam generator is set so that | HV1 | <| HV2 | so that the electron beam can be effectively extracted.
Note that the preliminary ionization may not be performed using an electron beam. For example, as described in Patent Document 4, a sliding discharge is generated in the chamber and may be performed by ultraviolet rays from the sliding discharge. Good.

The control unit 14 is composed of, for example, a processor and a memory, etc., and executes the program stored in the memory to generate the high voltage pulse based on the command from the control unit 40 of the exposure machine as described above. The unit 12, the gas supply unit 20, the gas exhaust unit 13, the preliminary ionization power source 18, etc. are controlled by the operation procedure described below.
1 shows a monitor unit 22 and a film thickness measuring means 19 for monitoring the film thickness of the deposit deposited in the chamber 1, and a warning display means for displaying that the amount of the deposit in the chamber 1 has increased. These operations are described in the fourth and fifth embodiments described later.

(2) Operation of the EUV light source apparatus of the present embodiment The following describes the exposure process in the EUV light source apparatus of the first embodiment of the present invention and the cleaning process during the exposure process interruption. In the following description, a case where preliminary ionization is performed by the preliminary ionization unit shown in FIG. 1 will be described.
2, 3, and 4 are flowcharts showing the operation procedure of the EUV light source apparatus of the present embodiment, FIGS. 2 and 3 are flowcharts showing the operation procedure in the exposure process, and FIG. 4 is the operation procedure in the cleaning process. FIG. 5 is a time chart showing operations in the exposure process and the cleaning process.
In the following first to third embodiments, the case where the cleaning process is automatically performed while the exposure process is interrupted will be described. However, as in the fourth embodiment to be described later, the worker performs the cleaning process. Can also be done manually.
(A) Exposure Processing Step As shown in the flowcharts of FIGS. 2 and 3 and the time chart of FIG. 5, the operation in the exposure processing step is as follows.
(i) In FIGS. 2 and 5, a standby signal is sent from the controller 40 of the exposure machine to the controller 14 of the EUV light source apparatus. Here, the shutter 21 is in a closed state (step S101 in FIG. 2, a in FIG. 5).

(ii) Upon receiving the standby signal, the control unit 14 of the EUV light source device opens the valve V1 that opens and closes the SnH ₄ gas flow path and closes the valve V2 that opens and closes the Xe gas flow path. In addition, the control unit 14 of the EUV light source device that has received the standby signal controls the operation of the gas flow rate regulator MFC1 based on parameters previously input to the setting unit so that the SnH ₄ gas flow rate becomes a predetermined value. (Step S102, f, g, h in FIG. 5).
By this step, SnH ₄ gas whose flow rate is set by the MFC 1 is introduced into the chamber 1 of the EUV light source device through the gas inlet 2. In order to facilitate understanding, here, only one SnH ₄ gas supply path is used as the source gas supply path, and dilution of SnH ₄ gas and rare gas is not considered.
(iii) Based on the pressure data sent from the pressure monitor 15, the control unit 14 of the EUV light source apparatus performs gas exhaust so that the pressure of the high-density and high-temperature plasma generation unit 9 becomes a predetermined pressure (for example, 1 to 20 Pa). The unit 13 is controlled to adjust the gas exhaust amount (step S103, j in FIG. 5).

(iv) The control unit 14 of the EUV light source apparatus sends an open signal of the shutter 21 to the shutter drive control unit 16 (step S104).
(v) Upon receiving the shutter open signal, the shutter drive control unit 16 drives the shutter drive mechanism 21a to open the shutter 21 (step S105, k in FIG. 5).
(vi) The control unit 14 of the EUV light source device sends a standby completion signal to the control unit 40 of the exposure machine (step S106, not shown in FIG. 5).
(vii) Upon receiving the standby completion signal, the controller 40 of the exposure apparatus sends out an EUV light emission command signal to the controller 14 of the EUV light source device (step S107, b in FIG. 5).
(viii) Upon receiving the EUV light emission command signal, the control unit 14 of the EUV light source apparatus controls the preliminary ionization power source 18 to irradiate the high-density and high-temperature plasma generation unit 9 with the electron beam from the preliminary ionization unit 17 and perform preliminary ionization. At the same time, a trigger signal is sent to the high voltage pulse generator 12 (step S108, l, m in FIG. 5).

(ix) The high voltage pulse generator 12 that has received the trigger signal applies pulse power between the first main discharge electrode 3a (cathode) and the second main electrode (anode) 3b.
A creeping discharge is generated on the surface of the insulating material 3c, and the first main discharge electrode 3a and the second main discharge electrode 3b are substantially short-circuited, and the first main discharge electrode 3a and the second main discharge electrode 3 A large pulse current flows between the main discharge electrodes 3b. Thereafter, high-density and high-temperature plasma is generated in the high-density and high-temperature plasma generator 9 by Joule heating due to the pinch effect, and EUV light having a wavelength of 13.5 nm is emitted from this plasma (step S109, n in FIG. 5).
(x) The emitted EUV light is reflected by the EUV collector mirror 5 provided on the second main discharge electrode 3b side (anode), and includes an EUV light extraction unit including wavelength selection means (for example, an optical filter) 8. 6, the light is emitted to an irradiation unit (not shown) which is an exposure system side optical system (step S110).

(xi) Hereinafter, in accordance with exposure specifications, pulsed EUV light is repeatedly emitted until an EUV radiation stop signal (e in FIG. 5) is input from the control unit of the exposure machine to the control unit of the EUV light source device. . That is, in step S111, it is verified whether an EUV radiation stop signal is input from the controller 40 of the exposure machine to the controller 14 of the EUV light source apparatus, and when the above signal is not input at the time of verification (when No). ) Proceeds to step S107, and the above-described processing is repeated.
On the other hand, when the EUV radiation stop signal is input (Yes), the process proceeds to step S112 in FIG. 3, and the control unit 14 of the EUV light source apparatus stops outputting the EUV light emission command. As a result, the high voltage pulse generator 12 stops the generation of the high voltage pulse, and the standby ionization power source 18 stops the power supply to the backup ionization unit (b, l, m in FIG. 5). In addition, the discharge operation in the EUV light generation unit constituted by the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c is stopped.
This EUV radiation stop signal corresponds to an EUV radiation stop signal when the exposure process is ended, and corresponds to an EUV radiation stop signal when the exposure process is stopped. For example, the exposure of the wafer is completed, and is issued at the beginning of a rest period in which the exposed workpiece is replaced with the next unexposed workpiece. That is, the EUV radiation pause signal substantially corresponds to a signal for informing the start of work exchange.
(xii) A shutter close signal is sent from the control unit 14 of the EUV light source device to the shutter drive control unit 16 (step S113, k in FIG. 5).
Accordingly, the shutter drive control unit 16 drives the shutter drive mechanism 21a to close the shutter 21. Further, the valve V1 is closed, and the supply of SnH ₄ gas is stopped (step S114, g in FIG. 5).

(xiii) The control unit 14 of the EUV light source apparatus determines whether there is a cleaning signal (step S115).
When the cleaning process is always performed during the EUV radiation pause period, the EUV radiation pause signal can be used as the cleaning signal. In this case, the cleaning process is started each time the EUV radiation pause signal is given.
For example, when cleaning is required, or when the number of times of EUV light emission reaches a predetermined number as described in the embodiments described later, or the film thickness measured by the film thickness measuring means 19 is a threshold value. If the cleaning process is not performed every EUV radiation suspension period, the cleaning may be performed only when a cleaning signal is sent from the control unit 40 of the exposure machine.
For example, when an operator inputs a cleaning command, the control unit 14 of the EUV light source apparatus notifies the exposure unit control unit 40 to that effect, and when the exposure unit control unit 40 sends an EUV radiation pause signal, A cleaning signal is sent to the control unit 14 of the EUV light source device.
In the following first to third embodiments, it is assumed that the cleaning unit 40 generates a cleaning signal in addition to the EUV radiation pause signal when cleaning is performed. It may be a signal.

(xiv) When there is the cleaning signal (c in FIG. 5), the control unit 14 of the EUV light source apparatus shifts to the cleaning mode. In the case of performing cleaning, the process goes to step S118, and cleaning described later in FIG. 4 is started.
If the cleaning signal is not generated, the control unit 14 of the EUV light source apparatus determines whether there is an apparatus operation stop signal. If the apparatus operation stop is not performed, the process returns to step S101 in FIG.
On the other hand, if the apparatus operation stop signal is input, the gas exhaust unit 13 is stopped and the operation of the apparatus is stopped (step S117).
In some cases, EUV radiation is paused or terminated without sending an EUV radiation stop signal from the exposure unit controller 40 to the control unit 14 of the EUV light source device.
In such a case, for example, the control unit 14 of the EUV light source apparatus measures the elapsed time from the previous EUV light emission command signal, and when this elapsed time exceeds a predetermined time, the EUV radiation is paused or terminated. Judge that Detailed procedures for this are omitted.

(B) Cleaning process step during exposure processing interruption (when EUV light generation is stopped) As shown in the flowchart of FIG. 4 and the time chart of FIG. It is as follows.
(i) As described above, when an EUV radiation pause signal is sent from the exposure unit control unit 40 to the control unit 14 of the EUV light source device (e in FIG. 5), the shutter 21 is closed and the valve V1 is closed. Then, the supply of SnH ₄ gas is stopped (g in FIG. 5).
Here, when the cleaning signal is input as described above (c in FIG. 5), the control unit 14 opens the valve V2 (the valve V1 is closed), and supplies it to the high-density and high-temperature plasma generation unit 9. The gas to be switched is switched from SnH ₄ gas, which is a raw material gas for EUV radiation, to Xe gas, which is a cleaning gas. Further, the gas flow rate adjuster MFC2 is controlled to adjust the Xe gas flow rate.
That is, the control unit 14 of the EUV light source apparatus controls the operation of the gas flow rate adjuster MFC2 based on parameters previously input to the setting unit so that the Xe gas flow rate becomes a predetermined value (step S201, FIG. 5). H, i).
Through this step, Xe gas whose flow rate is set by the MFC 2 is introduced into the EUV light source device through the gas inlet 2.

(ii) The control unit 14 of the EUV light source device controls the gas exhaust unit 13 based on the pressure data sent from the pressure monitor 15 so that the pressure of the high-density and high-temperature plasma generation unit 9 becomes a predetermined pressure, The gas exhaust amount is adjusted (step S202).
Note that the Xe gas flow rate and the pressure of the high-density and high-temperature plasma generation unit 9 are set so that a rare gas (Xe gas) discharge plasma most suitable for removing deposits described later can be obtained.
(iii) The control unit 14 of the EUV light source apparatus is in a spontaneous discharge command mode in which a trigger signal is spontaneously sent to the high voltage pulse generation unit 12 without receiving an EUV light emission command signal from the control unit 40 of the exposure machine. Then, the trigger signal is sent to the high voltage pulse generator 12 (step S203, m in FIG. 5).
(iv) The high voltage pulse generator 12 that has received the trigger signal applies pulse power between the first main discharge electrode 3a (cathode) and the second main electrode (anode) 3b (step S204).

(v) Plasma discharge by Xe gas is generated in the high-density and high-temperature plasma generator 9 and its vicinity. The cleaning with the Xe gas plasma, SnH ₄ gas discharge (in EUV light generation), or, the first main discharge electrode 3a when the discharge stop from after EUV radiation pause signal send up shifts to spontaneous discharge command mode, the The Sn and / or Sn compound deposited on at least a part of the main discharge electrode 3b and the insulating portion 3c of the second is removed. That is, the electrodes 3a and 3b and the insulating part 3c are cleaned (step S205).
Hereinafter, a cleaning stop signal (corresponding to an exposure process end signal when the exposure process itself is ended, and a standby signal when restarting the exposure process) is sent from the exposure unit control unit 40 to the control unit 14 of the EUV light source apparatus. The above rare gas cleaning is repeated until input.
That is, in step S206, it is verified whether or not a cleaning stop signal is input from the controller 40 of the exposure machine to the controller 14 of the EUV light source apparatus, and at the time of verification, when the above signal is not input (when No). Moves to step S203.

(vi) On the other hand, when the cleaning stop signal is input (Yes), the process proceeds to the following step S207.
In step S207, the control unit 14 of the EUV light source device cancels the spontaneous discharge command mode, stops sending the trigger signal to the high voltage pulse generation unit 9, closes the valve V2, and this subroutine ends.
When the cleaning stop signal corresponds to the workpiece replacement end signal and the exposure process is resumed, the process proceeds from step S207 to step S101 shown in FIG. 2, and the exposure process is resumed. That is, as described above, when the standby signal is input, the above-described exposure process is resumed.

(C) Effects obtained by this embodiment In this embodiment, as described above, the gas supply unit has a function of supplying a rare gas, which is a cleaning gas, in addition to a source gas supply function of EUV radiation species, Furthermore, it has a switching function of both functions (corresponding to opening and closing of the valves V1 and V2 in the above example).
For this reason, the EUV radiation species into the container is included by the switching means in the rest period in which the exposure of the workpiece (for example, wafer) to be exposed is completed and the exposed workpiece is replaced with the next unexposed workpiece. A high voltage pulse generator is provided between the second container and the second main discharge electrode, which are grounded, and the first container and the first main discharge electrode, by switching the raw material to the rare gas supply. From the first main discharge electrode, the second main discharge electrode, and the communication hole of the EUV generator composed of the insulating material or in the vicinity of the communication hole, the rare gas (for example, Xe gas) High density and high temperature plasma can be formed.

In addition, the EUV light source material gas (for example, SnH ₄ ) generated during the generation of high-density and high-temperature plasma by discharge, the inside of the EUV light source device, particularly the first main discharge electrode, the second main discharge electrode, the insulation Impurities deposited on the material (in the case of using SnH ₄ as the source gas, Sn and / or Sn compound) are used to increase the amount of rare gas using the time during which the EUV light is not emitted when the exposure process is interrupted. A step can be performed in which high-speed ions or neutral atoms of a rare gas generated by adiabatic expansion of the high-density plasma collide with the impurities and the impurities are released.
That is, cleaning with rare gas plasma can be performed. Here, the rare gas does not generate fragments due to the decomposition of the metal clusters and the source gas unlike the case of the EUV radiation source gas (for example, SnH ₄ ) during plasma discharge. Therefore, there is no adhesion of impurities during plasma discharge, and only detachment occurs. Therefore, the deposit generated on the electrode or the like is scraped off and relatively reduced.
Further, when shifting from the EUV generation operation to the cleaning operation by the rare gas plasma, even if the discharge generation is stopped and the electrode temperature is lowered and impurities are deposited in the low temperature portion of the apparatus, Can be removed.
As a result, it is possible to remove deposits in the EUV light source device without reducing the operating time of the exposure apparatus equipped with the EUV generator.

In the above embodiment, the rare gas plasma generating means and the EUV radiation source gas (for example, SnH ₄ ) heating / excitation means (the first main discharge electrode to which the pulse power is supplied from the high voltage pulse generating section, the second The main discharge electrode).
For this reason, it is possible to generate a rare gas plasma discharge only by switching the supply of the source gas of the EUV radiation species to the supply of a rare gas that is a cleaning gas. Therefore, it is not necessary to separately provide a rare gas plasma discharge generating means in the container, and the apparatus can be configured compactly.
As described above, according to the present embodiment, it is possible to prevent the plasma discharge from becoming unstable due to the deposition of debris on the first main discharge electrode 3a and the second main discharge electrode 3b, and the insulating portion 3c. It is possible to prevent conduction between the first main discharge electrode 3a and the second main discharge electrode 3b due to the deposition of debris. For this reason, stable EUV light can be obtained.
Here, in the cleaning with ions or neutral atoms from the high-density high-temperature plasma of the rare gas, there is no need to apply a bias to the cleaning target because the ions or neutral atoms themselves have high kinetic energy. . Therefore, the insulating part 3c to which no bias is applied can also be cleaned.

Further, when performing the cleaning using the above-described adiabatic expansion of the high-density and high-temperature plasma, it is not always necessary to use a rare gas as the plasma raw material introduced into the container. However, for the reason that it is easy to adhere to each part in the container to be cleaned and there is no reactivity with each part in the container, it is most preferable to use a rare gas as the cleaning plasma raw material. It is valid.
In addition, since the rare gas plasma discharge is performed while flowing the rare gas (Xe gas), the range in which the rare gas plasma spreads is large. Therefore, depending on the rare gas plasma discharge conditions, the rare gas plasma may contact not only the first and second main discharge electrodes 3a and 3b and the insulating material 3c but also the upper part of the debris trap 4 and the EUV collector mirror 5. . At that time, impurities deposited on the debris trap 4 and the EUV collector mirror 5 (Sn and / or Sn compounds when SnH ₄ is used as the source gas) can also be removed by cleaning with rare gas plasma. It becomes possible.
When Xe gas is used as a cleaning rare gas, light in the EUV wavelength region including a wavelength of 13.5 nm is emitted from the plasma depending on the generation conditions of the high-density and high-temperature plasma. Since such light may lead to undesired exposure, it is desirable to close the shutter 21 before cleaning as described above.

In the above-described embodiment, the high voltage pulse generator 12 that applies high voltage pulses to the first main discharge electrode and the second main discharge electrode to heat and excite the source gas and the rare gas is also used. A high voltage pulse generator for heating and exciting the source gas and the rare gas may be provided.
Furthermore, a heating / excitation unit for heating and exciting the source gas and a heating / excitation unit for heating and exciting the rare gas may be provided.
If the exposure apparatus (not shown) has a shutter mechanism on the light incident side of the exposure apparatus optical system, the shutter, shutter drive mechanism, etc. can be omitted from the EUV light source apparatus of FIG. In this case, the opening / closing operation of the shutter in the operation procedure of the above-described embodiment is performed on the exposure machine side.
In addition, the workpieces are generally exchanged between cassettes provided in the exposure apparatus and capable of holding a plurality of workpieces. That is, a work is conveyed from the first cassette holding a plurality of unexposed works to a single exposure area. The conveyed workpiece is conveyed and held in the second cassette holding the exposed workpiece after the exposure process is completed. When the first cassette is empty and the second cassette is full of exposed workpieces, the first cassette is replaced with one that is full of unexposed workpieces, and the second cassette is an empty cassette. Will be replaced. In the description of FIG. 2, FIG. 3, FIG. 4, and FIG. 5, the exposure of the workpiece is completed as an example of the pause period, and the period for exchanging the exposed workpiece with the next unexposed workpiece is presented. The period may be this cassette exchange period.

(3) First Modification of First Embodiment Next, a first modification of the above embodiment will be described.
The apparatus configuration is the same as that shown in FIG. 1, and in this modification, immediately after the EUV radiation stop signal is input and the cleaning signal is input in the processing steps shown in FIGS. By shifting to the spontaneous discharge command mode, the noble gas cleaning process is shortened.
That is, in the above-described embodiment, no EUV light emission signal is input after the EUV radiation stop signal is input from the control unit 40 of the exposure machine to the control unit 14 of the EUV light source apparatus. Until the control unit 14 of the EUV light source device shifts to the spontaneous discharge command mode, the discharge operation in the EUV generation unit composed of the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c is Stop.
Therefore, during the discharge operation stop period, the temperature inside the EUV light source device, in particular, the first main discharge electrode and the second main discharge electrode are lowered. When SnH ₄ gas is used as the source gas, a portion of the metal cluster such as Sn, Sn _X and fragment SnH _{x of} the atomic gas that has been suspended comes into contact with the portion where the temperature has decreased, and Sn and / Or Sn compound deposits. By performing the cleaning process, these deposits are also removed. However, in this modification, the discharge operation is not performed, and the discharge operation is performed even during the switching of the supply gas type to the high-density and high-temperature plasma generation unit. Persist. Thereby, the temperature drop amount of the first and second main discharge electrodes 3a and 3b is also reduced, and the amount of Sn and / or Sn compound deposited on the first and second main discharge electrodes 3a and 3b is also reduced. For this reason, it becomes possible to shorten the rare gas cleaning process.

(A) Cleaning processing step Specifically, the cleaning processing step is as shown, for example, in the time chart of FIG. 6 (particularly, refer to the portion enclosed by an ellipse in the same drawing).
An EUV radiation pause signal is sent from the controller 40 of the exposure machine to the controller 14 of the EUV light source device (e in FIG. 6). As described above, this EUV radiation pause signal is issued at the beginning of a pause period in which exposure of a workpiece (for example, a wafer) to be exposed is completed and an exposed workpiece is replaced with the next unexposed workpiece.
The control unit 14 of the EUV light source apparatus that has received the EUV radiation pause signal is spontaneously generated without receiving the EUV emission command signal from the control unit 40 of the exposure machine when the cleaning signal is input (c in FIG. 6). Then, the process shifts to a spontaneous discharge command mode in which a trigger signal is sent to the high voltage pulse generator 9, and the trigger signal is sent to the high voltage pulse generator 12 (m in FIG. 6). Thereby, the discharge is maintained even after the EUV radiation pause signal is transmitted.

On the other hand, when the cleaning signal is generated, the control unit 14 of the EUV light source device first sends a shutter close signal to the shutter drive control unit 16. In response to this, the shutter drive controller 16 drives the shutter drive mechanism 21a to close the shutter 21 (k in FIG. 6).
Furthermore, the control unit 14 of the EUV light source device switches the gas supplied to the high-density and high-temperature plasma generation unit 9 of the EUV light source device from SnH ₄ gas, which is a source gas of EUV radiation, to Xe gas, which is a cleaning gas.
That is, the valve V1 for opening and closing the SnH ₄ gas flow path is closed, and the valve V2 for opening and closing the Xe gas flow path is opened (f, h in FIG. 6). In addition, the control unit 14 of the EUV light source device controls the operation of the gas flow rate adjuster MFC2 based on parameters previously input to the setting unit so that the Xe gas flow rate becomes a predetermined value. As a result, the Xe gas whose flow rate is set by the MFC 2 is introduced into the EUV light source device through the gas inlet 2 (i in FIG. 6).
Based on the pressure data sent from the pressure monitor 15, the control unit 14 of the EUV light source device controls the gas exhaust unit 13 so that the pressure of the high-density and high-temperature plasma generation unit 9 becomes a predetermined pressure, and the gas exhaust amount Adjust.
On the other hand, the high voltage pulse generator 12 that has received the trigger signal indicated by m in FIG. 6 applies pulse power between the first main discharge electrode 3a (cathode) and the second main discharge electrode 3b (anode). .

When Xe gas is introduced through the gas introduction port 2 and Xe gas is present in the high-density and high-temperature plasma generation unit 9 and its vicinity, the high-density and high-temperature plasma generation unit 9 and its vicinity are caused by Xe gas. Plasma discharge occurs. The cleaning with the Xe gas plasma, SnH ₄ gas discharge (in EUV light generation), or, the first main discharge electrode 3a when the discharge stop from after EUV radiation pause signal send up shifts to spontaneous discharge command mode, the The Sn and / or Sn compound deposited on at least a part of the main discharge electrode 3b and the insulating portion 3c of the second is removed. That is, the electrode and the insulating part are cleaned.
Thereafter, the rare gas cleaning described above is repeatedly performed until a cleaning stop signal is input from the controller 40 of the exposure machine to the controller 14 of the EUV light source device.
The following operations are the same as those described above, and it is verified whether or not a cleaning stop signal is input from the controller 40 of the exposure machine to the controller 14 of the EUV light source apparatus, and at the time of verification, the above signals are not input. The cleaning process is continued when (No), and the cleaning process is stopped when the signal is input (Yes).
When the cleaning process is stopped and a standby signal is input as described above, the exposure process is started.
The above processing can be realized by shifting “transition to the spontaneous discharge mode” in step S203 before step 201 in the flowchart of FIG.

(B) Effects of this Modification According to this modification, the same effects as in the first operation procedure can be obtained, and the following effects can be obtained.
That is, since the discharge is continued with the rare gas (Xe gas) even when the generation of EUV is interrupted, the temperature drop amount of the first and second main discharge electrodes is reduced, and Sn and / or The amount of deposited Sn compound also decreases. Therefore, it is possible to shorten the rare gas cleaning process.

(4) Second Modification of First Embodiment Here, in the first modification described above, if discharge with a rare gas is started before the shutter 21 is closed, undesired light may be emitted. Arise.
When it is necessary to avoid this, the above processing steps may be modified as shown in the time chart of FIG. 7 (particularly, refer to the portion surrounded by an ellipse in FIG. 7).
That is, as shown by k, h, m in FIG. 7, the process waits until the shutter 21 is closed. When the shutter 21 is closed, the valve V2 is opened to introduce a rare gas and shift to the spontaneous discharge mode.
In this case, the discharge operation is stopped after the EUV radiation stop signal is given from the control unit 40 of the exposure apparatus until the control unit 14 of the EUV light source device shifts to the spontaneous discharge command mode. For this reason, during the discharge operation stop period, for example, Sn and / or Sn compounds are deposited on the temperature drop portions of the first main discharge electrode 3a and the second main discharge electrode 3b.
However, since the discharge operation stop period in FIG. 7 is shorter than that in the first operation procedure shown in FIG. 5, the temperature drop amount of the first and second main discharge electrodes is also reduced. The amount of deposited Sn and / or Sn compound is also reduced. Therefore, it is possible to shorten the rare gas cleaning process.
The above process can be realized by adding a process of waiting until the shutter is closed before step S201 in the flowchart of FIG.

(5) Third Modification of First Embodiment In the first embodiment and the first modification described above, in the cleaning process, the supply of EUV radiation source gas and the supply of a rare gas as a cleaning gas are performed. Is switched off with either the source gas supply path or the rare gas supply path closed with the valve V1 or V2 closed, and the other gas flow regulator (MFC1 or MFC2) that is not blocked. ) Was operating.
However, when switching the gas supply, first, the valves V1 and V2 are opened to open both gas supply paths, and the gas flow rate regulators MFC1 and MFC2 gradually increase the gas flow rate in the Xe gas supply flow path. At the same time, the gas flow rate of the SnH ₄ gas supply flow path may be gradually decreased to close the valve V1 of the SnH ₄ gas supply flow path where the gas flow rate is substantially zero. By performing such processing, it becomes easy to control the pressure in the chamber at the time of gas switching (that is, the pressure of the high-density and high-temperature plasma generator).

The cleaning process steps of this modification are shown in the time chart of FIG.
FIG. 8 shows a case where the present modification is applied to the cleaning process shown in FIG. 4, and the same can be applied to the cleaning process shown in the time charts of FIGS.
As shown in FIG. 8, the control unit 14 of the EUV light source device opens the valve V1 that opens and closes the SnH ₄ gas supply channel and the valve V2 that opens and closes the Xe gas channel (f in FIG. 8). H).
Next, the control unit 14 of the EUV light source apparatus uses parameters previously input to the setting unit so that the flow rate of the SnH ₄ gas flow path gradually decreases and the flow rate flow rate of the Xe gas gradually increases. Based on the above, the operation of the gas flow regulators MFC1 and MFC2 is controlled (g and i in FIG. 8).
Further, the control unit 14 of the EUV light source device closes the valve V1 when the gas flow rate of the SnH ₄ gas flow path becomes almost zero (f in FIG. 8).
The other steps in FIG. 8 are the same steps as those in the first embodiment described above, and thus the description thereof is omitted here.
The above process does not perform the valve V1 closing process in step S114 of the flowchart of FIG. 3, and after step S201 of FIG. 4, the gas flow rate of the SnH ₄ gas flow path gradually decreases as described above and the Xe gas This can be realized by adding a process for gradually increasing the flow rate gas flow rate.

(6) Fourth Modified Example of First Embodiment In the cleaning process described above, after performing a process of switching between a source gas supply of EUV radiation species and a rare gas supply as a cleaning gas, a high-density high-temperature plasma The pressure of the generating part 9 was adjusted to be a predetermined pressure.
However, it is conceivable that SnH ₄ gas remains in the chamber including the high-density and high-temperature plasma generation unit 9 for a while even after the gas supply is switched. The staying SnH ₄ gas may form a tin mirror in the low temperature part inside the chamber.
In consideration of such circumstances, in this modification, a step of exhausting SnH ₄ gas that may remain is provided in the following procedure.
When the exposure process is completed, the valve V1 of the SnH ₄ gas supply channel is closed (the valve V2 of the Xe gas supply channel is closed) and the supply of SnH ₄ gas to the high-density and high-temperature plasma generator 9 is stopped. In addition, voltage application from the high voltage pulse generator 12 to the first and second main discharge electrodes 3a and 3b is also stopped, but the exhaust by the gas exhaust unit 13 continues and remains in the chamber 1. The SnH ₄ gas is exhausted. This evacuation is continued for a predetermined time, and then the valve V2 is opened (the valve V1 remains closed) to supply Xe gas, and the voltage from the high voltage pulse generator 12 is also applied to generate plasma by Xe gas. Is generated.
As described above, after the exposure process, the SnH ₄ gas remaining in the chamber 1 including the high-density and high-temperature plasma generation unit 9 is exhausted, so that the remaining SnH ₄ gas generates a low-temperature portion inside the chamber during the Xe gas plasma generation. Can prevent the formation of a tin mirror.

FIG. 9 shows a time chart of the cleaning process step of this modification (particularly, refer to the portion surrounded by an ellipse in the figure).
In FIG. 9, when the control unit 14 of the EUV light source device closes the valve V1 that opens and closes the SnH ₄ gas supply flow path according to the EUV radiation suspension command, the exhaust measurement means (exhaust timer) provided in the control unit 14 is closed. ) Is started (j in FIG. 9).
As described above, after the EUV radiation pause signal is sent from the control unit 40 of the exposure machine, the EUV composed of the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c. The discharge operation at the generator is stopped.
Further, in order to adjust the pressure inside the chamber 1 including the high-density and high-temperature plasma generation unit 9 during supply of SnH ₄ gas, the inside of the chamber is exhausted by a predetermined exhaust amount by the gas exhaust unit 13.

Next, the control unit 14 of the EUV light source device supplies a gas to be supplied to the high-density and high-temperature plasma generation unit 9 of the EUV light source device after a predetermined time has elapsed (that is, after the exhaust time measuring means has been counted) as a raw material of EUV radiation species. Switching from SnH ₄ gas, which is a gas, to Xe gas, which is a cleaning gas.
That is, the valve V2 that opens and closes the Xe gas flow path is opened, and the operation of the gas flow rate regulator MFC2 is controlled based on the parameters input in advance to the setting unit so that the Xe gas flow rate becomes a predetermined value ( FIG. 9 h, i). As a result, Xe gas whose flow rate is set by the MFC 2 is introduced into the EUV light source device via the gas inlet 2.
Here, the predetermined time is a time during which the SnH ₄ gas remaining from the inside of the chamber is sufficiently exhausted by the gas exhaust unit 13, and is set in advance in the control unit 14 of the EUV light source device.
The other parts of FIG. 9 are the same as the processes described with reference to FIGS. 2 to 5 and are not described here.

(7) Fifth Modification of the First Embodiment In the cleaning process step of the above-described embodiment, when generating a rare gas (Xe gas) plasma discharge, the first and second high voltage pulse generators 12 Pulse power is applied between the main discharge electrodes 3a and 3b. At that time, no preionization is performed as in the case of generating EUV light.
In this modification, pre-ionization is also performed when the rare gas (Xe gas) plasma discharge is generated in the cleaning process described above.
When pre-ionization is not performed, when there is a change in the pressure of the rare gas, the pulse power applied from the high voltage pulse generator, the rare gas plasma discharge becomes non-uniform, and the first and second main discharges A so-called arc-like discharge in which the discharge is concentrated on a part of the electrodes 3a and 3b may occur. When such arc-like discharge occurs in the portion where the Sn and / or Sn compound is deposited on the first and second main discharge electrodes 3a and 3b, relatively large particle-shaped Sn having a diameter of 100 nm to several tens of μm and / Or Sn compound scatters in the 1st container 1a and the 2nd container 1b.

Since the particles are separated from the electrode by an arc-like discharge in which energy is concentrated, they are scattered relatively far and reach, for example, the debris trap 4 and the EUV collector mirror 5. Sn and / or Sn compounds that have reached the debris trap 4 adhere to the debris trap 4 and are deposited. Therefore, the amount of EUV light passing through the debris trap 4 is reduced by the amount deposited.
Further, the Sn and / or Sn compound that reaches the EUV collector mirror 5 and deposits causes a situation in which the EUV light reflectance of the EUV collector mirror 5 decreases.
As described above, Sn and / or Sn compounds resulting from arc-like discharge have a relatively large particle size. Therefore, it takes a lot of time to remove it by cleaning with rare gas plasma. In general, the debris trap 4 and the EUV collector mirror 5 are separated from the first and second main discharge electrodes 3a and 3b where mainly rare gas plasma discharge is generated by several tens mm to several hundreds mm. The amount that the rare gas plasma reaches from the point where the discharge of the rare gas plasma occurs is inversely proportional to the square of the distance. Therefore, the amount of rare gas plasma that reaches the debris trap 4 and the EUV collector mirror 5 is also reduced, and the cleaning with the rare gas plasma is less effective for the above-mentioned distance.

That is, when impurities with a large particle size adhere to and deposit on a portion where the distance from the discharge of the rare gas plasma occurs, a huge amount of time is spent trying to remove by cleaning with the rare gas plasma. In practice, it is impossible to suppress degradation of the device performance due to impurities.
Here, when the rare gas (Xe gas) plasma discharge is generated, if pre-ionization is also performed, the occurrence of discharge concentration is suppressed, and uniform rare gas plasma can be formed. That is, since the occurrence of discharge concentration is suppressed, relatively large particles of Sn and / or Sn compounds reach the debris trap 4 and the EUV collector mirror 5 that have a large distance from the rare gas plasma formation region. Is almost gone. Therefore, the time spent for cleaning with the rare gas plasma can be greatly shortened, and it is easy to suppress the deterioration of the apparatus performance due to impurities.
In addition, since it is possible to form uniform rare gas plasma by preliminary ionization, cleaning with the rare gas plasma can be performed uniformly.
Specifically, in the flowchart and time chart of the cleaning process shown in FIGS. 4 to 9, the control unit 14 of the EUV light source device controls the preliminary ionization power source 18 and also performs the preliminary ionization unit 17 during the cleaning process. Then, an electron beam is irradiated toward the high-density and high-temperature plasma generation unit 9 to perform preionization.
By doing so, pre-ionization is also performed when the rare gas (Xe gas) plasma discharge is generated in the cleaning process described above. In addition, since it is not necessary to change especially about the other step in each operation | movement procedure, description is abbreviate | omitted here.

2. Second Embodiment (1) Apparatus Configuration FIG. 10 is a diagram showing a configuration of an EUV light source apparatus according to a second embodiment of the present invention.
Differences from the one shown in Figure 1, the H ₂ gas supply source 20c and the valve V3 and a gas flow regulator MFC3 provided in the gas supply unit 20, in the cleaning process, together with the noble gas into the chamber 1, H ₂ gas Is to supply. The other configuration is the same as that shown in FIG. 1, and the description of the same configuration is omitted.
When cleaning is performed only with a rare gas (for example, Xe), Sn attached to the electrode surface by high-speed ions generated from discharge receives kinetic energy from the high-speed ions and is evaporated or peeled off from the electrode surface.
These Sn ride on the flow of the discharge gas and move away from the vicinity of the electrodes. However, if there is a low temperature part in the path to the exhaust system, it adheres to that part and remains in the chamber 1.
Therefore, in this embodiment, Sn is gasified by mixing hydrogen with a cleaning rare gas. The chemical reaction formula is shown in Formula 1.
Sn + 2H ₂ (+ hv) → Sn + 4H → SnH ₄ (Formula 1)

Hydrogen normally exists in a molecular state, but when energy is applied from the outside, the H—H bond is broken and it is decomposed into hydrogen radicals. This hydrogen radical is rich in chemical reactivity, and is bonded to the electrode, which is a problem in this case, and bonds to Sn to form stannane (SnH ₄ ) or a Sn hydrogen compound.
When hydrogen gas is mixed with the gas being cleaned, as shown above, the external energy of the photon energy from the discharge plasma and the light source is received and decomposed into hydrogen radicals, which combine with Sn adhering to the electrode, and are caused by fast ions. Together with the cleaning, the Sn adhered to the electrode is cleaned by two effects. Further, the floating Sn separated from the electrode by cleaning the electrode is combined with the floating hydrogen radical, and becomes stannane or Sn hydrogen compound, which is gasified. By being gasified, it is possible to prevent redeposition in a low temperature part from the electrode to the exhaust system, and it is easy to exhaust from the chamber 1.

(2) Operation of the EUV light source apparatus of this embodiment FIG. 11 is a time chart showing the operation of this embodiment. The operation in the exposure processing step is the same as the operation shown in the flowcharts of FIGS. 2 and 3, and the operation in the cleaning processing step will be described below.
(i) As described above, when the EUV radiation stop signal is sent from the controller 40 of the exposure machine to the controller 14 of the EUV light source device (e in FIG. 11), the shutter 21 is closed and the valve V1 is closed. Then, the supply of SnH ₄ gas is stopped (m, f, g in FIG. 11).
When the cleaning signal is input as described above (c in FIG. 11), the control unit 14 opens the valve V2 (valve V1 is closed) and supplies the high-density and high-temperature plasma generation unit 9 to the valve V2. The gas to be switched is switched from SnH ₄ gas, which is a raw material gas for EUV radiation, to Xe gas, which is a cleaning gas. Further, the gas flow rate adjuster MFC2 is controlled to adjust the Xe gas flow rate.
At the same time, the valve V3 is opened, hydrogen gas H ₂ is supplied into the chamber 1, and the gas flow rate regulator MFC3 is controlled to adjust the gas flow rate of the hydrogen gas H ₂ (h, i in FIG. 11). , J, k).

(ii) The control unit 14 of the EUV light source device controls the gas exhaust unit 13 based on the pressure data sent from the pressure monitor 15 so that the pressure of the high-density and high-temperature plasma generation unit 9 becomes a predetermined pressure, Adjust the gas displacement.
The Xe gas flow rate, the H ₂ gas flow rate, and the pressure of the high-density and high-temperature plasma generation unit 9 can obtain a rare gas (Xe gas) discharge plasma that is most suitable for removal of deposits described later, and can be cleaned. Set to be done effectively.
The following processing is the same as the processing shown in FIG. 4, and as described above, the mode is shifted to the spontaneous discharge command mode, the trigger signal is sent to the high voltage pulse generator 12, and the first main discharge electrode 3a, pulse power is applied to the second main electrode 3b.
Thereby, cleaning by Xe gas plasma is performed. In accordance with this, as described above, the deposit attached to the electrode or the like by the hydrogen radical is gasified and exhausted from the chamber 1.
Thereafter, the rare gas cleaning described above is repeated until a cleaning stop signal is input from the controller of the exposure machine to the controller of the EUV light source device.

In the present embodiment, as described above, not only a rare gas is supplied as a cleaning gas but also a hydrogen (H ₂ ) gas is supplied, and not only cleaning with a rare gas plasma but also so-called reactive sputtering is performed. Since this is done, the cleaning time can be shortened.
For example, if SnH ₄ is supplied as a source gas and Xe gas or H ₂ gas is used as a cleaning gas, Sn and / or Sn compounds adhering to the inside of the EUV light source device are not only cleaned by Xe plasma, It reacts with the hydrogen plasma to become Sn hydride with a high vapor pressure and is exhausted by the exhaust means without reattaching to the low temperature part.
In the above embodiment, the case where the H ₂ gas is supplied in the cleaning process described in the first embodiment has been described, but the cleaning process in the first to fifth modifications described above. In this case, H ₂ gas may be supplied.

3. Third Embodiment (1) Apparatus Configuration FIG. 12 is a diagram showing a configuration of an EUV light source apparatus according to a third embodiment of the present invention.
The difference from the one shown in FIG. 1 is that a configuration in which the second container can be divided into two spaces in the chamber at the time of cleaning with Xe gas plasma is adopted. It is the same as that shown, and the description of the same configuration is omitted.
In the first embodiment described above, Xe gas is supplied to the high-density and high-temperature plasma generator 9, and discharge is performed by the EUV generator composed of the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c. The generated Xe gas plasma is generated, and the impurities deposited on the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c are particularly removed by cleaning with the Xe gas plasma.
According to the first embodiment, depending on the Xe gas plasma discharge conditions, the Xe gas plasma is not limited to the first and second electrodes 3a and 3b, the insulating material 3c, but also the debris trap 4 and the upper part of the EUV collector mirror 5. You may come in contact with. At that time, impurities deposited on the top of the debris trap and EUV collector mirror (Sn and / or Sn compound when SnH ₄ is used as the source gas of EUV radiation species) should also be removed by cleaning with rare gas plasma. Is possible.

However, when the impurities deposited on the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c are removed by cleaning with a rare gas plasma, the first main discharge electrode 3a collides with the Xe gas plasma. The impurities detached from the second main discharge electrode 3b and the insulating material 3c are not without possibility of reattaching to the EUV collector mirror 5.
In this case, the reflectance with respect to 13.5 nm of the EUV collector mirror 5 is lowered, and as a result, the intensity of the EUV light emitted to the outside is lowered.
In the present embodiment, in order to eliminate the possibility of the above-described problems, the first main discharge electrode 3a, the second main discharge electrode 3b, the insulation are formed in the second container 1b during cleaning with Xe gas plasma. The space is separated into a space where the material 3c and the debris trap 4 are located and a space where the EUV collector mirror 5 is located. A specific configuration will be described below.

The EUV light source apparatus according to the present embodiment includes a shutter 24a that blocks emission of light such as EUV light to the outside in the space between the debris trap 4 and the EUV collector mirror 5 in the second container 1b of the chamber 1. A shutter 24b is provided. The shutter 24a and the shutter 24b are held so as to be movable in the left-right direction on the paper surface of FIG.
When the shutter 24a and the shutter 24b are in the closed state, the emission of light such as EUV light is blocked, and the first main discharge electrode 3a and the second main discharge electrode 3b are disposed in the second container 1b. The space is divided into a space where the insulating material 3c and the debris trap 4 are located (hereinafter referred to as a cleaning space) and a space where the EUV collector mirror is located (hereinafter referred to as a blocking space).
The shutter 24a and the shutter 24b are opened and closed by operating the shutter drive mechanism 25a and the shutter drive mechanism 25b based on the control of the shutter drive control unit 26a and the shutter drive control unit 26b. The shutter drive control unit 26a and the shutter drive control unit 26b drive and control the shutter drive mechanism 25a and the shutter drive mechanism 25b based on a shutter open / close command from the control unit 14 of the EUV light source device.

In addition, a pressure monitor 15b and a gas exhaust unit 13b are provided in a cleaning space formed by dividing the interior of the second container 1b when the shutter 24a and the shutter 24b are closed during cleaning with Xe gas plasma. It is done.
The pressure monitor 15b monitors the pressure in the cleaning space. In addition to the pressure monitor 15b, a pressure monitor 15a is provided for monitoring the pressure in the blocking space (in the chamber 1 when the shutters 24a and 24b are open).
Further, the gas exhaust unit 13b adjusts the pressure in the cleaning space and exhausts gas. In addition to the gas exhaust unit 13b, a gas exhaust unit 13a for exhausting the blocking space (in the chamber 1 when the shutters 24a and 24b are open) is provided.
Pressure data as detection results of the pressure monitors 15a and 15b is sent to the control unit 14 of the EUV light source device. The gas exhaust units 13a and 13b are controlled by the control unit 14.
When the shutters 24a and 24b are in the open state, the pressure in the chamber 1 is monitored by the pressure monitor 15a, and the chamber is exhausted by the gas exhaust unit 13a through the gas exhaust port 7a.
When the shutters 24a and 24b are closed, the pressures in the cleaning space and the blocking space are monitored by the pressure monitors 15a and 15b, respectively, and the cleaning space is exhausted by the gas exhaust unit 13a through the gas exhaust port 7b. At the same time, the shut-off space is exhausted by the gas exhaust unit 13b through the gas exhaust port 7a.

In the EUV light source device of the first embodiment shown in FIG. 1, the SnH ₄ gas supply path and the Xe gas supply path are coupled downstream of the flow rate adjusting units MFC1 and MFC2 to form one system supply path. , Connected to the gas inlet 2 provided in the first container of the chamber.
Although such a configuration may be adopted as it is, in this embodiment, as shown in FIG. 12, the SnH ₄ gas supply channel and the Xe gas supply channel from the gas supply unit are completely separated, Is configured to be connected to the gas inlet 2.
With this configuration, when the gas supply is switched, gas mixing due to the residual gas in the gas supply path does not occur, and a gas with a desired purity can be supplied.
In FIG. 12, the separated SnH ₄ gas supply flow path and Xe gas supply flow path are connected to one gas introduction port 2, but two gas introduction ports are provided in the first container 1a. You may make it connect a gas supply flow path.

(2) Operation of EUV light source apparatus of this embodiment FIGS. 13 and 14 are exposure process steps of this embodiment, FIG. 15 is a flowchart of cleaning process steps, and FIG. 16 is a time chart of this embodiment. Hereinafter, the operation procedure of the present embodiment will be described with reference to the flowchart and the time chart.
(A) Exposure processing step The exposure processing step is substantially the same as the processing of the first embodiment, and the same step name is used for the same step, and the flowcharts of FIGS. 13 and 14 and the time chart of FIG. Will be described in brief.
(i) A standby signal is sent from the control unit 40 of the exposure machine to the control unit 14 of the EUV light source device (step S1011, a in FIG. 16).
(ii) Upon receiving the standby signal, the control unit 14 of the EUV light source device sends open signals for the shutters 24a and 24b to the shutter drive control unit 26a and the shutter drive control unit 26b, respectively. Here, when the gas exhaust unit 13b is operating, it is stopped (step S1012).

(iii) Upon receipt of the shutter open signal, the shutter drive control unit 26a and the shutter drive control unit 26b drive the shutter drive mechanism 25a and the shutter drive mechanism 25b to open the shutter 24a and the shutter 24b, respectively (step S1013). FIG. 16 l).
Here, unlike the first embodiment, the shutters (shutters 24a and 24b) are opened before the SnH ₄ gas is supplied if the shutter 24a and the shutter 24b remain closed. This is because the inside 1b is separated into two spaces, and it becomes impossible for the gas exhaust unit 13a to perform the subsequent pressure adjustment process of the high-density and high-temperature plasma generation unit 9 after the SnH ₄ gas supply.
(iv) The control unit 14 of the EUV light source device opens the valve V1 and closes the valve V2 to supply the SnH ₄ gas at a predetermined flow rate to the high-density and high-temperature plasma generation unit 9, and operates the gas flow rate regulator MFC1. (Step S102, f and g in FIG. 16)
(v) The control unit 14 of the EUV light source apparatus controls the gas exhaust unit 13a to set the pressure of the high-density and high-temperature plasma generation unit 9 to a predetermined pressure based on the pressure data sent from the pressure monitor 15a. The exhaust amount is adjusted (step S103).

(vi) The control unit 14 of the EUV light source device sends a standby completion signal to the control unit 40 of the exposure machine (step S106).
(vii) Upon receiving the standby completion signal, the controller 40 of the exposure apparatus sends an EUV light emission command signal to the controller 14 of the EUV light source device (step S107, FIG. 16B).
(viii) Upon receiving the EUV light emission command signal, the control unit 14 of the EUV light source apparatus controls the preliminary ionization power source 18 to irradiate the high-density and high-temperature plasma generation unit 9 with the electron beam from the preliminary ionization unit 17 and perform preliminary ionization. At the same time, a trigger signal is sent to the high voltage pulse generator 12 (step S108, m, n in FIG. 16).
(ix) The high voltage pulse generator 12 that has received the trigger signal applies pulse power between the first main discharge electrode 3a and the second main electrode 3b, and the high-density and high-temperature plasma generator 12 Plasma is generated, and EUV light emission from the plasma is realized (step S109, o in FIG. 16).
(x) The emitted EUV light is reflected by the EUV collector mirror 5 and is emitted from an EUV light extraction unit 6 including a wavelength selection unit 8 to an irradiation unit (not shown) which is an exposure machine side optical system (step S110). ).

(xi) Hereinafter, in accordance with exposure specifications, pulsed EUV light is repeatedly emitted until an EUV radiation stop signal (e in FIG. 16) is input from the controller of the exposure machine to the controller of the EUV light source device. . That is, in step S111, it is verified whether or not the EUV radiation stop signal is input. If the signal is not input (No), the process proceeds to step S107, and the above-described processing is repeated. On the other hand, when the EUV radiation stop signal is input (Yes), the process goes to step S112 in FIG. 16 to stop the output of the EUV emission command.
As a result, the high voltage pulse generator 12 stops the generation of the high voltage pulse, and the standby ionization power source 18 stops the power supply to the backup ionization unit (m, n in FIG. 16). Discharging operation stops.

(xii) A shutter close signal is sent from the control unit 14 of the EUV light source device to the shutter drive control units 26a and 26b. Accordingly, the shutter drive control units 26a and 26b drive the shutter drive mechanisms 25a and 25b to close the shutters 24a and 24b. Further, the valve V1 is closed and the supply of SnH ₄ gas is stopped. Further, the operation of the gas exhaust unit 13b is started (steps S1131 to S1141, k and l in FIG. 16).
(xiii) The control unit 14 of the EUV light source device determines whether a cleaning signal is input. When this cleaning signal is input, the process goes to step S118, and cleaning described later in FIG. 15 is started.
(xiv) When the cleaning signal is not generated, the control unit 14 of the EUV light source apparatus determines whether there is an apparatus operation stop signal, and if not, the process returns to step S1011 of FIG. When the apparatus operation stop signal is input, the gas exhaust unit 13a is stopped (when the gas exhaust unit 13b is operating, the gas exhaust unit 13b is also stopped), and the operation of the apparatus is stopped (step S117).

(B) Cleaning process during exposure process interruption (when EUV light generation is stopped) The cleaning process is substantially the same as that shown in the first embodiment. This will be briefly described with reference to the flowchart of FIG. 15 and the time chart of FIG.
(i) As described above, when an EUV radiation stop signal is sent from the controller 40 of the exposure machine to the controller 14 of the EUV light source device (e in FIG. 16), the shutters 24a and 24b are closed, and the valve V1. Closes and the supply of SnH ₄ gas is stopped (f, g in FIG. 16).
Here, when the cleaning signal is input as described above (c in FIG. 16), the control unit 14 opens the valve V2 (the valve V1 is closed) and supplies it to the high-density and high-temperature plasma generation unit 9. The gas to be switched is switched to Xe gas which is a cleaning gas. Further, the gas flow rate adjuster MFC2 is controlled to adjust the Xe gas flow rate (h, i in FIG. 16).

(ii) The control unit 14 of the EUV light source device controls the gas exhaust unit 13b based on the pressure data sent from the pressure monitor 15b so that the pressure of the high-density and high-temperature plasma generation unit 9 becomes a predetermined pressure, The gas exhaust amount is adjusted (step S2021).
(iii) The control unit 14 of the EUV light source apparatus is in a spontaneous discharge command mode in which a trigger signal is spontaneously sent to the high voltage pulse generation unit 12 without receiving an EUV light emission command signal from the control unit 40 of the exposure machine. Then, the trigger signal is sent to the high voltage pulse generator 12 (step S203, n in FIG. 16).
(iv) The high voltage pulse generator 12 that has received the trigger signal applies pulse power between the first main discharge electrode 3a (cathode) and the second main electrode (anode) 3b (step S204). (v) Plasma discharge by Xe gas is generated in the high-density and high-temperature plasma generator 9 and its vicinity. By this cleaning with Xe gas plasma, Sn and / or Sn compounds deposited on at least a part of the first main discharge electrode, the second main discharge electrode, and the insulating portion are removed (step S205).

Hereinafter, a cleaning stop signal (corresponding to an exposure process end signal when the exposure process itself is ended, and a standby signal when restarting the exposure process) is sent from the exposure unit control unit 40 to the control unit 14 of the EUV light source apparatus. The above rare gas cleaning is repeated until input.
That is, in step S206, it is verified whether or not a cleaning stop signal is input from the controller 40 of the exposure machine to the controller 14 of the EUV light source apparatus, and at the time of verification, when the above signal is not input (when No). Moves to step S203.
(vi) On the other hand, when the cleaning stop signal is input (Yes), the process proceeds to the following step S207.
In step S207, the control unit 14 of the EUV light source device cancels the spontaneous discharge command mode, stops sending the trigger signal to the high voltage pulse generation unit 9, closes the valve V2, and this subroutine ends.

(C) Effects obtained by this embodiment The EUV light source apparatus of this embodiment has the same effects as the EUV light source apparatus according to the first embodiment described above, but can further obtain the following effects.
In the present embodiment, during the cleaning process using the Xe gas plasma, in the second container, the space containing the first main discharge electrode 3a, the second main discharge electrode 3b, the insulating material 3c, the debris trap 4 and the EUV collection are collected. The optical mirror 5 and the like are separated into a space, and a cleaning process using rare gas plasma is performed only in the space where the first main discharge electrode 3a, the second main discharge electrode 3b, the insulating material 3c, and the debris trap 4 are present. .
For this reason, the impurities separated from the first main discharge electrode 3a, the second main discharge electrode 3b, and the insulating material 3c by colliding with the Xe gas plasma are not reattached to the EUV collector mirror 5. Therefore, the reflectance of the EUV collector mirror 5 with respect to 13.5 nm light due to the reattached impurities does not decrease, and as a result, the intensity of the EUV light emitted to the outside does not decrease.
In this embodiment as well, preionization may be performed in the cleaning processing step as in the fifth modification of the first embodiment described above.
Thereby, when generating rare gas (Xe gas) plasma discharge, the occurrence of discharge concentration is suppressed, and uniform rare gas plasma can be formed. Therefore, the relatively large particulate Sn and / or Sn compound hardly reaches the debris trap 4 and the EUV collector mirror 5 which have a large distance from the formation region of the rare gas plasma, so that cleaning with the rare gas plasma is possible. The time spent can be greatly shortened, and it is easy to suppress a decrease in device performance due to impurities.
In addition, since it is possible to form uniform rare gas plasma by preliminary ionization, cleaning with the rare gas plasma can be performed uniformly.
Further, the first to fourth modifications of the first embodiment may be applied to the present embodiment. In the present embodiment, as in the second embodiment, in the cleaning process, H ₂ Gas may be introduced.

4). Fourth Embodiment In the above-described embodiments, the exposure processing pause time is a pause period for exchanging an exposed workpiece with the next unexposed workpiece or a pause interval for exchanging a cassette holding a plurality of workpieces. In addition, a cleaning process using a rare gas plasma has been performed.
On the other hand, the amount of impurities deposited in the EUV light source device increases as the period in which the pulsed EUV light is emitted (that is, the number of times the pulsed EUV light is emitted increases). Therefore, when the number of times the pulsed EUV light is emitted exceeds a predetermined value, the deposit can be effectively removed by performing the cleaning process.
Therefore, in this embodiment, the number of times the pulsed EUV light is emitted is counted, and when the count reaches a predetermined value, a warning display is displayed on the EUV light source. When the warning is displayed, for example, the operator manually switches the gas supplied to the high-density and high-temperature plasma generation unit from SnH ₄ gas to Xe gas to remove impurities deposited on the electrodes and the like.
When exposure is performed by an exposure machine, the exposure process cannot normally be interrupted until a series of exposure operations are completed. For example, when a warning is output, a warning is output. This is notified to the controller 40 of the exposure machine, and when an EUV radiation stop signal is sent from the controller 40 of the exposure machine, a cleaning process is performed.

(1) Apparatus Configuration The configuration of the EUV light source apparatus according to the fourth embodiment is equivalent to, for example, the configuration example of the EUV light source apparatus according to the first to third embodiments shown in FIGS. 1, 10, and 12. However, in this embodiment, the warning display means 23 shown in FIGS. 1, 10, and 12 is used to display a warning when the number of times the pulsed EUV light is emitted exceeds a predetermined value. Other configurations are the same as those described in the above embodiment, and a detailed description thereof is omitted.
As shown in FIGS. 1, 10, and 12, the first container 1 a of the chamber 1 is provided with a warning display means 23, and the control unit 14 of the EUV light source apparatus according to the present embodiment is configured to transmit EUV light. Counting means (not shown) for counting the number of times of radiation is provided.
Then, the control unit 14 of the EUV light source apparatus of the present embodiment causes the warning display means 23 to output a warning signal when the count value of the counting means reaches a predetermined value. The warning display means 23 is, for example, a warning lamp. The warning signal may be sent by an external device such as an exposure apparatus, or an alarm sound may be generated by using a voice generating means (not shown) when the warning display means is turned on or when the warning signal is sent. Good.

(2) Operation of the EUV light source apparatus of this embodiment FIGS. 17 and 18 are flowcharts of the exposure processing steps of this embodiment. Hereinafter, the operation of this embodiment will be described with reference to the flowchart.
(A) Exposure processing step The exposure processing step of this embodiment counts the number of times EUV light is emitted, and outputs a warning signal when the count value reaches a predetermined value. The exposure process steps of this embodiment will be briefly described below.

(i) A standby signal is sent from the controller 40 of the exposure machine to the controller 14 of the EUV light source device. Here, the shutter 21 is closed (step S301 in FIG. 17).
Here, it is assumed that the control unit 14 of the EUV light source apparatus has a counter (not shown) as described above, and the counter count is reset (in an initial state).
(ii) Upon receiving the standby signal, the control unit 14 of the EUV light source device opens the valve V1 that opens and closes the SnH ₄ gas flow path and closes the valve V2 that opens and closes the Xe gas flow path. In addition, the control unit 14 of the EUV light source device that has received the standby signal controls the operation of the gas flow rate regulator MFC1 based on parameters previously input to the setting unit so that the SnH ₄ gas flow rate becomes a predetermined value. .
Further, the control unit 14 of the EUV light source device is based on the pressure data sent from the pressure monitor 15 so that the pressure of the high-density and high-temperature plasma generation unit 9 becomes a predetermined pressure (for example, 1 to 20 Pa). 13 is controlled to adjust the gas displacement. Further, the shutter drive mechanism 21a is driven to open the shutter 21 (step S302).

(iii) The control unit 14 of the EUV light source apparatus sends a standby completion signal to the control unit 40 of the exposure machine (step S303).
(iv) Upon receipt of the standby completion signal, the controller 40 of the exposure apparatus sends an EUV light emission command signal to the controller 14 of the EUV light source device (step S304).
(v) Upon receiving the EUV light emission command signal, the control unit 14 of the EUV light source apparatus controls the preliminary ionization power source 18 to irradiate the high-density and high-temperature plasma generation unit 9 with the electron beam from the preliminary ionization unit 17 and perform preliminary ionization. At the same time, a trigger signal is sent to the high voltage pulse generator 12 (step S305).
(vi) After sending the trigger signal, the counter provided in the control unit of the EUV light source device is updated by one (step S306).
(vii) The high voltage pulse generator 12 that has received the trigger signal applies pulse power between the first main discharge electrode (cathode) 3a and the second main electrode (anode) 3b. As a result, high-density and high-temperature plasma is generated in the high-density and high-temperature plasma generator 9, and EUV light having a wavelength of 13.5 nm is emitted from this plasma (step S307).

(viii) Next, a test is performed to determine whether or not light has been emitted a predetermined number of times (nm). That is, in step S308, when the count number n of the counter is n, n <nm
If so, the process proceeds to step S310. When n = nm, the process proceeds to step S309.
The above-mentioned predetermined number of times of light emission nm is the number of times of EUV light emission when an adverse effect due to the amount of impurities deposited in the EUV light source device cannot be overlooked (that is, a trigger signal input to the high voltage pulse generator). The minimum number of times.
The amount of impurities deposited in the EUV light source device is considered to depend on the EUV light intensity and the number of times of EUV light emission. On the other hand, the EUV light intensity depends on the operating conditions of the EUV light source device such as the amount of SnH ₄ gas introduced, the pressure in the chamber, and the amount of pulse power applied between the first and second main discharge electrodes from the high voltage pulse generator. Dependent.

Therefore, when the operating conditions of the EUV light source apparatus according to the exposure specifications are known in advance, the above-mentioned predetermined number of times of light emission nm is calculated in advance based on the EUV light intensity corresponding to the above-described operating conditions, and control of the EUV light source apparatus. Stored in the unit 14.
(ix) When n <nm, an adverse effect due to the amount of impurities deposited in the EUV light source device (particularly, the first and second main discharge electrodes and the insulating material) is in an overlookable state.
Therefore, in step S310, it is verified whether or not an EUV radiation stop signal is input from the exposure unit controller 40 to the control unit 14 of the EUV light source apparatus. If the EUV radiation stop signal is not input (No), the process proceeds to step S304. Migrate and repeat the above process.
On the other hand, when n ≧ nm, an adverse effect due to the amount of impurities deposited in the EUV light source device (in particular, the first and second main discharge electrodes and the insulating material) cannot be overlooked. Therefore, in step S309, the control unit 14 of the EUV light source device turns on a warning lamp that is a warning display means. Further, a counter value for counting the number of times of EUV emission is reset to an initial value. Further, the controller 40 of the exposure machine is notified that the warning lamp has been turned on. Then, the process goes to step S310.

When notified that the warning lamp is lit, the control unit 40 of the exposure machine outputs an EUV radiation stop signal at a timing at which the exposure process can be interrupted. Further, as described above, a cleaning signal may be transmitted in addition to the EUV radiation stop signal.
The EUV radiation stop signal is a signal issued at the beginning of a pause period in which an exposed workpiece is replaced with the next unexposed workpiece as described above (the EUV radiation pause signal of the first to third embodiments). It may be.
Here, the predetermined number of times of light emission nm is not set to the number of times in which the adverse effect due to the amount of impurities deposited in the EUV light source device cannot be overlooked, but set to a small value with some margin. Also good. Operator determines that the maintenance timing the warning display is output, for example, as a maintenance timing such as after exposure work is completed by switching the manual gas supplied to the high density and high temperature plasma generating unit in Xe gas SnH ₄ gas Impurities deposited on the electrodes and the like are removed.

(x) In step S310, it is verified whether an EUV radiation stop signal is input from the control unit 40 of the exposure machine. If the EUV radiation stop signal is input (Yes), output of the EUV emission command is stopped. . Further, a shutter close signal is sent to the shutter drive controller 16 (step S311 in FIG. 18). Accordingly, the shutter drive control unit 16 drives the shutter drive mechanism 21a to close the shutter 21.
(xi) If the warning display means 23 is not lit, the control unit 14 of the EUV light source apparatus determines whether there is an apparatus operation stop signal (step S315). Return.
When the warning display means 23 is lit, the operation stops at this stage and enters a standby state. The worker confirms that the warning display means is turned on and manually performs the cleaning process described in the first to third embodiments. That is, the control unit 14 of the EUV light source apparatus is manually controlled to generate a rare gas (Xe gas) plasma discharge and perform a cleaning process as described above.
Since the specific control contents are the same as those in the cleaning process of the above-described embodiment, the description thereof is omitted here. When the cleaning process is completed, the warning display means is turned off.

(xi) When the manual cleaning process is completed and the warning display means 23 is turned off (steps S313 and S314), the control unit 14 of the EUV light source device notifies the exposure unit control unit 40 that the cleaning process has been completed. The standby state is released.
(xii) The control unit 14 of the EUV light source apparatus determines whether there is an apparatus operation stop signal (step S315). If the apparatus operation is not stopped, the process returns to step S301.
If the apparatus operation stop signal is input, the gas exhaust unit 13 is stopped and the operation of the apparatus is stopped (step S316).

FIG. 19 is a time chart for explaining the cleaning process according to this embodiment.
As shown in the figure, the control unit of the EUV light source apparatus is provided with a counter for counting the number of times of EUV light emission as described above, and the count value of this counter increases every time EUV light emission is repeated. When the count value of the counter exceeds nm, the counter is reset and the warning display means 23 is turned on.
When an EUV radiation stop signal is given from the control unit 40 of the exposure machine, the output of the EUV light emission command is stopped as described above. Further, the shutter 21 is closed.
In this state, the worker manually performs the cleaning process described above. When the cleaning process is finished, the warning display means 23 is turned off.

(B) Effects obtained by this embodiment This embodiment counts the number of times pulsed EUV light is emitted, and causes the EUV light source to display a warning when the count reaches a predetermined value. When the warning is displayed, the operator manually switches the gas supplied to the high-density and high-temperature plasma generation unit from SnH ₄ gas to Xe gas and removes impurities deposited on the electrodes and the like.
Therefore, it is possible to perform the cleaning process only when the cleaning process is necessary, and it is more efficient than performing the cleaning process each time the EUV radiation is stopped.

(3) Modified example of the fourth embodiment In the above-described embodiment, when the number of times of EUV light emission (n) reaches the predetermined number of times of light emission (nm), a warning lamp is displayed and the cleaning process is performed manually. . However, the cleaning process may be performed automatically as described below.
20 and 21 are flowcharts showing the exposure processing steps of the present embodiment, and the operation procedure in the present embodiment will be described below.
The procedure up to comparing / testing the number of EUV emission (n) and the predetermined number of emission (nm) is the same as the procedure from step S301 to S308 in the fourth embodiment described above, so the explanation is omitted here. To do.
(i) If it is determined in step S308 that n <nm, the adverse effect due to the amount of impurities deposited in the EUV light source device can be overlooked, as described in the fourth embodiment. In step S310, it is verified whether or not an EUV radiation stop signal is input from the control unit of the exposure apparatus to the control unit of the EUV light source apparatus.
If the EUV radiation stop signal is not input (No), the process proceeds to step S304 and the above process is repeated.

(ii) On the other hand, when n ≧ nm, the control unit 14 of the EUV light source apparatus sends an alarm signal to the control unit 40 of the exposure machine. Further, a counter value for counting the number of times of EUV emission is reset to an initial value. Then, the process goes to step S310.
When the alarm is notified, the controller 40 of the exposure apparatus outputs an EUV radiation stop signal at a timing at which the exposure process can be interrupted.
(iii) In step S310, it is verified whether an EUV radiation stop signal is input from the controller 40 of the exposure machine. If the EUV radiation stop signal is not input (No), the process returns to step S304 and the exposure process is continued.
When the EUV emission stop signal is input from the control unit 40 of the exposure machine (Yes), the process goes to step S311 to stop outputting the EUV emission command. In addition, a shutter close signal is sent to the shutter drive control unit 16. Accordingly, the shutter drive control unit 16 drives the shutter drive mechanism 21a to close the shutter 21.
If an alarm is notified to the controller 40 of the exposure machine as described above (step S3121), the cleaning mode is started and the cleaning process is started (step S3131).
(iv) Next, the control unit 14 of the EUV light source apparatus determines whether there is an apparatus operation stop signal (step S315). If the apparatus operation is not stopped, the process returns to step S301.
If the apparatus operation stop signal is input, the gas exhaust unit 13 is stopped and the operation of the apparatus is stopped (step S316).

In the cleaning process, for example, the cleaning procedure as described in the first embodiment is partially changed and applied. In this embodiment, the control unit 14 of the EUV light source device also serves as a second counter (counter for counting the number of times the EUV light is emitted) for counting the number of trigger signals during the cleaning process. And the cleaning process is performed until the count value reaches a predetermined value.
FIG. 22 is a flowchart showing a cleaning procedure in this embodiment.
(i) The control unit of the EUV light source apparatus changes the gas supplied to the high-density and high-temperature plasma generation unit of the EUV light source apparatus from SnH ₄ gas, which is a source gas of EUV radiation, to Xe gas, which is a cleaning gas using rare gas plasma. Switch.
That is, the valve V1 that opens and closes the SnH ₄ gas flow path is closed, and the valve V2 that opens and closes the Xe gas flow path is opened. Further, the control unit of the EUV light source device controls the operation of the gas flow rate adjuster MFC2 based on parameters previously input to the setting unit so that the Xe gas flow rate becomes a predetermined value (step S201). Through this step, Xe gas whose flow rate is set by the MFC 2 is introduced into the EUV light source device through the gas inlet 2.

(ii) The control unit of the EUV light source device controls the gas exhaust unit 13 based on the pressure data sent from the pressure monitor 15 so that the pressure of the high-density and high-temperature plasma generation unit becomes a predetermined pressure. The amount is adjusted (step S202).
(iii) The control unit 14 of the EUV light source apparatus is in a spontaneous discharge command mode in which a trigger signal is spontaneously sent to the high voltage pulse generation unit 12 without receiving an EUV light emission command signal from the control unit 40 of the exposure machine. Then, the trigger signal is sent to the high voltage pulse generator (step S203).
(vi) As described above, the control unit 14 of the EUV light source apparatus has a counter (not shown), and updates the count by one after sending the trigger signal (step S2035).
(vii) The high voltage pulse generator 12 that has received the trigger signal applies pulse power between the first main discharge electrode 3a (cathode) and the second main electrode 3b (anode) (step S204).

(viii) Plasma discharge by Xe gas is generated in the vicinity of the high-density and high-temperature plasma generating portion. The cleaning with the Xe gas plasma, SnH ₄ gas discharge (in EUV light generation), or, the first main discharge electrode 3a when the discharge stop from after EUV radiation pause signal send up shifts to spontaneous discharge command mode, the The Sn and / or Sn compound deposited on at least a portion of the second main discharge electrode 3b and the insulating portion 3c is removed (step S205).
Here, the removal amount of impurities deposited in the EUV light source device by cleaning with rare gas (for example, Xe gas) plasma increases as the number of pulsed rare gas plasma discharges generated during the rare gas supply increases. To do.
On the other hand, the removal amount of impurities (for example, Sn and / or Sn compound) by one pulsed noble gas plasma discharge is the first and second from the amount of Xe gas introduced, the pressure in the chamber, and the high voltage pulse generator. It depends on the operating conditions of the EUV light source device such as the amount of pulse power applied between the main discharge electrodes.
Therefore, when the operation conditions of the EUV light source device according to the exposure specifications and the cleaning operation conditions by the rare gas plasma are known in advance, the deposition is performed when the EUV light emission is performed for the predetermined light emission number nm of the above-mentioned EUV light emission number. The number of rare gas plasma discharges (ne) necessary for removing the impurities is calculated in advance and stored in the control unit 14 of the EUV light source device.

(ix) In the next step S2055, it is verified whether or not the number of rare gas plasma discharges has reached the above ne.
When n <ne, the impurities deposited in the EUV light source device (particularly, the first and second main discharge electrodes 3a and 3b and the insulating material 3c) are not sufficiently removed. Therefore, cleaning with the rare gas plasma is continued. That is, at the time of verification, when n ≧ ne is No, the process proceeds to step S203.
On the other hand, when n ≧ ne is Yes at the time of verification in step S2055, the process proceeds to step S2061, and in step S2061, the control unit 14 of the EUV light source device cancels the spontaneous discharge command mode, and the trigger signal high voltage The delivery to the pulse generator is stopped and the valve V2 is closed. Further, the count of the second counter is reset and the process is terminated.
When the exposure process is restarted, the process proceeds from step S2061 to step S301 shown in FIG.

In this modification as well, the predetermined number of times of light emission nm is not set to the number of times in which the adverse effect due to the amount of impurities deposited in the EUV light source device cannot be overlooked, but set to a small number with some margin. You may keep it.
In step S309, when the exposure unit control unit 40 receives an alarm signal, the exposure unit control unit 40 sends an EUV radiation stop signal to the control unit 14 of the EUV light source apparatus. The timing at which the alarm signal is received is one workpiece. In some cases, such as during the exposure process, a series of exposure processes cannot be interrupted. In such a case, the control unit 40 of the exposure machine sends out an EUV radiation stop signal to the control unit of the EUV light source apparatus after receiving the alarm signal as described above and after the processing of the workpiece being exposed is completed.
Further, when the preparation for exposure of the workpiece is completed during the cleaning process, the controller of the exposure machine may send a forced termination command signal to the EUV light source device at any timing in steps S201 to S2061. In this case, the control unit 14 of the EUV light source device forcibly ends the process when receiving the forcible end signal.

Furthermore, in this embodiment, preliminary ionization may be performed as in the fifth modification of the first embodiment described above.
In that case, as described above, when the rare gas (Xe gas) plasma discharge is generated, the occurrence of discharge concentration is suppressed, and uniform rare gas plasma can be formed. Therefore, relatively large particulate Sn and / or Sn compounds hardly reach the debris trap or EUV collector mirror having a large distance from the rare gas plasma formation region, and are consumed for cleaning with the rare gas plasma. The time can be greatly shortened, and it becomes easy to suppress a decrease in apparatus performance due to impurities.
In addition, since it is possible to form uniform rare gas plasma by preliminary ionization, cleaning with the rare gas plasma can be performed uniformly.

FIG. 23 is a time chart for explaining the cleaning process according to the present embodiment.
As shown in the figure, the control unit of the EUV light source apparatus is provided with a counter for counting the number of times of EUV light emission as described above, and the count value of this counter increases every time EUV light emission is repeated. When the count value of the counter exceeds nm, the counter is reset and an alarm is notified to the control unit 40 of the exposure apparatus.
As described above, the controller 40 of the exposure machine outputs an EUV radiation stop signal at a timing when the series of exposure processes is completed and the EUV light radiation can be stopped.
When the EUV emission stop signal is given, the output of the EUV emission command is stopped as described above. Further, the shutter 21 is closed.
Next, the control unit 14 of the EUV light source device shifts to a spontaneous discharge command mode in which a trigger signal is spontaneously transmitted to the high voltage pulse generation unit 12 and transmits the trigger signal to the high voltage pulse generation unit 12. As a result, a plasma discharge is generated by Xe gas in the high-density and high-temperature plasma generation portion and its vicinity, and cleaning is performed.
On the other hand, the number of plasma discharges by Xe gas is counted by the second counter, and when this count value reaches a predetermined value ne, the cleaning process is terminated.

5. Fifth Embodiment In the above-described third embodiment, the number of times the pulsed EUV light is emitted is counted, so that the inside of the EUV light source device (particularly, the first and second main discharge electrodes and the insulating material). The effect of the amount of impurities deposited on the surface was judged.
In this embodiment, instead of the count, the amount of impurities deposited in the EUV light source device (especially, the first and second main discharge electrodes 3a and 3b and the insulating material 3c) is monitored. When the value reaches a predetermined value, a warning is displayed on the EUV light source.
When the warning is displayed, for example, the operator manually switches the gas supplied to the high-density and high-temperature plasma generation unit from SnH ₄ gas to Xe gas to remove impurities deposited on the electrodes and the like.

(1) Apparatus Configuration The configuration of the EUV light source apparatus according to the present embodiment may be the same as the configuration example of the EUV light source apparatus according to the first embodiment shown in FIG. Therefore, detailed description is omitted.
In the above description related to FIG. 1, the description of the configuration related to the present embodiment has been omitted. Therefore, this configuration will be described below.
In FIG. 1, a monitor unit 22 is provided in the vicinity of the second main discharge electrode 3 b in the second container 1 b of the chamber 1. The monitor unit 22 is for detecting the amount of impurities deposited in the EUV light source device (in particular, the first and second main discharge electrodes 3a and 3b and the insulating material 3c). It is used as a monitor for checking the presence or absence of deposits and calculating the cleaning processing rate of deposits.
The monitor unit 22 is, for example, a crystal oscillator type film thickness monitor. That is, the deposit state of the deposit is detected by detecting the deposit deposited on the film thickness monitor disposed in the EUV light source device.
A detection signal from the monitor unit 22 is sent to the film thickness measuring means 19. Based on the received detection signal, the film thickness measuring means 19 calculates the deposit amount of the deposit deposited in the EUV light source device, the cleaning processing speed, etc., and determines the presence or absence of the deposit. The calculation result and the determination result are sent from the film thickness measurement means to the control unit of the EUV light source device.

(A) Exposure processing step and cleaning processing step The exposure processing step and cleaning processing step of this embodiment are basically the same as the flowcharts shown in FIGS. 17 and 18, but in this embodiment, FIG. Step S306 is deleted, and instead, a step of calculating the deposition amount of impurities deposited in the container by the film thickness measuring means is added. Also, step S308 in FIG. 17 is deleted, and a step of comparing the film thickness tc with the film thickness set value tm is added instead. The other processes are the same as those described with reference to FIGS. Therefore, only the above changes will be described here.
(i) When the processing of steps S301 to S305 is performed as described above and EUV light is emitted, a detection signal is sent from the monitor unit 22 to the film thickness measuring means 19, and the film thickness measuring means 19 Based on the signal, the accumulation amount tc of the deposit in the EUV light source device is calculated, and the calculation result is sent to the control unit 14 of the EUV light source device.
(ii) The control unit 14 of the EUV light source apparatus that has received the calculated deposition amount data from the film thickness measuring means 19 examines the magnitude of the calculated deposition amount tc and the threshold value tm.
When tc <tm, the adverse effect due to the amount of impurities deposited in the EUV light source device can be overlooked, and the cleaning process is not performed.

On the other hand, when tc ≧ tm, an adverse effect due to the amount of impurities deposited in the EUV light source device cannot be overlooked. Therefore, as described above, the warning lamp which is the warning display means 23 is turned on to perform manual cleaning processing by the worker.
Note that the control unit 14 of the EUV light source device stores in advance a threshold tm of the deposit amount, and this threshold tm of the deposit amount is adversely affected by the amount of impurities deposited in the EUV light source device. This is the threshold value when it becomes impossible to overlook.
Other processes are the same as those described with reference to FIGS.
The threshold value tm of the deposition amount is not set to a threshold value in a state where the adverse effect due to the deposition amount of impurities deposited in the EUV light source device cannot be overlooked, but may be set to a small value with some margin. Good. When the warning is displayed, the operator determines that it is a maintenance time. For example, as a maintenance after the completion of the exposure operation, the operator manually switches the gas supplied to the high-density and high-temperature plasma generation unit from SnH ₄ gas to Xe gas. The impurities deposited on the electrodes and the like may be removed.

FIG. 24 is a time chart for explaining the cleaning process according to the present embodiment.
As shown in the figure, every time EUV light is emitted, the measured film thickness value detected by the monitor unit 22 increases, and when the measured film thickness value reaches the deposition amount threshold value tm, the warning lamp is turned on.
When the warning lamp is turned on and an EUV radiation stop signal is given from the controller 40 of the exposure machine, the output of the EUV emission command is stopped as described above. Further, the shutter 21 is closed.
In this state, the worker manually operates the control unit 14 of the EUV light source device to perform a cleaning process. When the cleaning process is finished, the warning display means 23 is turned off.

(B) Effects obtained by this embodiment In this embodiment, the amount of impurities deposited in the EUV light source device (especially the first and second main discharge electrodes and the insulating material) is monitored, and the amount deposited is accumulated. When the amount threshold tm is reached, a warning is displayed on the EUV light source. When the warning is displayed, for example, the operator manually switches the gas supplied to the high-density and high-temperature plasma generating unit from SnH ₄ gas to Xe gas to remove impurities deposited on the electrodes and the like. .
Therefore, it is possible to perform the cleaning process only when the cleaning process is necessary, which is more efficient than performing the cleaning process each time the EUV radiation is stopped.

(2) Modification of Fifth Embodiment In the above-described embodiment, when the impurity deposition amount tc obtained by monitoring and calculating reaches the deposition amount threshold value tm, a warning lamp is displayed and the cleaning process is manually performed. I was trying to do it. However, when the deposition amount reaches the threshold value tm, as shown in FIGS. 20, 21, and 22, the cleaning process may be automatically performed.
FIG. 25 is a time chart for explaining the cleaning process according to this embodiment.
As shown in the figure, every time the EUV light is emitted, the measured film thickness value detected by the monitor unit 22 increases, and when the measured film thickness value reaches the deposition amount threshold value tm, an alarm is issued. Is sent out.
Thereby, when an EUV radiation stop signal is given from the controller 40 of the exposure machine, the output of the EUV light emission command is stopped as described above. Further, the shutter 21 is closed.
Next, the control unit 14 of the EUV light source device shifts to a spontaneous discharge command mode in which a trigger signal is spontaneously transmitted to the high voltage pulse generation unit 12 and transmits the trigger signal to the high voltage pulse generation unit 12. As a result, a plasma discharge is generated by Xe gas in the high-density and high-temperature plasma generation portion and its vicinity, and cleaning is performed.
On the other hand, when the film thickness of the deposit reaches te by performing cleaning, the cleaning process is terminated.

Also in this modification, the threshold value tm of the deposition amount is not set to a threshold value in a state in which the adverse effect due to the deposition amount of impurities deposited in the EUV light source device can not be overlooked, but to some extent with some margin. You may set it.
Further, as described above, when the timing at which the alarm signal is received is during the exposure process for one workpiece, the control unit 40 of the exposure machine performs processing of the workpiece during the exposure process after receiving the alarm signal. After completion, an EUV radiation pause signal may be sent to the control unit 14 of the EUV light source device.
Further, when the preparation for exposure of the workpiece is completed during the cleaning process, the controller 40 of the exposure machine may send a forced termination command signal to the EUV light source device.
Also in this embodiment, preliminary ionization may be performed as in the fifth modification of the first embodiment described above. Thereby, when generating rare gas (Xe gas) plasma discharge, the occurrence of discharge concentration is suppressed, and uniform rare gas plasma can be formed.
Therefore, relatively large particulate Sn and / or Sn compounds hardly reach the debris trap or EUV collector mirror having a large distance from the rare gas plasma formation region, and are consumed for cleaning with the rare gas plasma. The time can be greatly shortened, and it becomes easy to suppress a decrease in apparatus performance due to impurities.
Further, since the uniform ionization of the rare gas plasma can be formed by the preliminary ionization, the cleaning with the rare gas plasma can be performed uniformly.
Further, the fourth and fifth embodiments are applied to the second and third embodiments, the number of times of EUV light emission is counted, and when the count value reaches a predetermined value, or impurity deposition When the amount reaches a predetermined value, a warning may be generated or cleaning may be started automatically.

In the first to fifth embodiments, the SnH ₄ gas plasma discharge and the Xe gas plasma discharge are performed by the single high voltage pulse generator 12, but the power source for discharging the Xe gas ( A pulse discharge power source, a DC discharge power source, an RF discharge power source, or the like) may be provided separately. For example, the discharge of SnH ₄ for generating EUV light and the discharge of a rare gas (Xe gas) for cleaning have different applications, so that the optimum power supply characteristics (current value, voltage value, pulse waveform) are different for each. , Frequency) is different.
When the power supply characteristics are extremely different, the power supply gives priority to one efficiency and lowers the other efficiency. In that case, it is possible to maintain each efficiency (EUV light and cleaning) by providing separately.
In addition, when supplying Sn as an EUV radiation species to the high-density and high-temperature plasma generation unit, not only SnH ₄ but also Sn can be supplied as Sn vapor by evaporation by laser irradiation to Sn or by self-heating of the Sn supply source by discharge. Good.
Further, Li (lithium) may be adopted as the EUV radiation species. In that case, the source gas may be Li vapor or Li compound.
In the cleaning method of the present invention, when the surfaces of the first and second main discharge electrodes, the insulating material, the EUV collector mirror, etc. are cleaned, the shape of the discharge part such as the electrodes is of course the drive current waveform and By appropriately setting the discharge frequency, the cleaning gas type and flow rate, the gas pressure distribution inside the container, and the like, it is possible to control the distribution of the cleaning region and the cleaning speed.

It is a figure which shows the structure of the EUV light source device of 1st Example of this invention. It is a flowchart (1) which shows the operation | movement procedure in the exposure process of the 1st Example of this invention. It is a flowchart (2) which shows the operation | movement procedure in the exposure process of the 1st Example of this invention. It is a flowchart which shows the operation | movement procedure in the cleaning process process of 1st Example of this invention. It is a time chart which shows operation | movement of a 1st Example. It is a time chart which shows the operation | movement of the 1st modification of a 1st Example. It is a time chart which shows operation | movement of the 2nd modification of a 1st Example. It is a time chart which shows the operation | movement of the 3rd modification of a 1st Example. It is a time chart which shows the operation | movement of the 4th modification of a 1st Example. It is a figure which shows the structure of the EUV light source device of the 2nd Example of this invention. It is a time chart which shows operation | movement of the EUV light source apparatus of the 2nd Example of this invention. It is a figure which shows the structure of the EUV light source device of the 3rd Example of this invention. It is a flowchart (1) which shows the operation | movement procedure in the exposure process of the 3rd Example of this invention. It is a flowchart (2) which shows the operation | movement procedure in the exposure process of the 3rd Example of this invention. It is a flowchart which shows the operation | movement procedure in the cleaning process process of the 3rd Example of this invention. It is a time chart which shows operation | movement of the EUV light source device of the 3rd Example of this invention. It is a flowchart (1) which shows the operation | movement procedure in the exposure process of the 4th Example of this invention. It is a flowchart (2) which shows the operation | movement procedure in the exposure process of the 4th Example of this invention. It is a time chart which shows operation | movement of the EUV light source apparatus of the 4th Example of this invention. It is a flowchart (1) which shows the operation | movement procedure in the exposure process of the modification of the 4th Example of this invention. It is a flowchart (2) which shows the operation | movement procedure in the exposure process of the modification of the 4th Example of this invention. It is a flowchart which shows operation | movement of the modification of the 4th Example of this invention. It is a time chart explaining the cleaning process by the modification of the 4th Example of this invention. It is a time chart which shows operation | movement of the 5th Example of this invention. It is a time chart which shows the operation | movement of the modification of the 5th Example of this invention. It is a figure which shows the structural example of a DPP type EUV light source device. It is a figure which shows the state which Sn and / or Sn compound deposited on the surface of the 1st, 2nd main discharge electrode and an insulating material.

Explanation of symbols

1 Chamber 2 Gas inlet 3a Main discharge electrode (cathode)
3b Main discharge electrode (anode)
3c Insulating material 4 Debris trap 5 EUV collector mirror 6 EUV light extraction part 7 Gas outlet 8 Wavelength selection means 9 High density high temperature plasma generation part 12 High voltage pulse generation part 13 Gas exhaust unit 14 Control part (EUV light source device)
DESCRIPTION OF SYMBOLS 15 Pressure monitor 16 Shutter drive control part 17 Pre-ionization unit 18 Pre-ionization power supply 19 Film thickness measurement means 20 Gas supply unit 21 Shutter 22 Monitor unit 23 Warning display means 24a Shutter 24b Shutter

Claims (15)

A container in which high-density and high-temperature plasma is generated, and a raw material supply means for supplying a raw material containing the extreme ultraviolet light emitting species and / or the compound of the extreme ultraviolet light emitting species in the container;
Preionization means for preionizing the supplied raw material in the container;
Heating / excitation means for heating / exciting the raw material pre-ionized in the container to generate high-density high-temperature plasma;
Condensing optical means for condensing extreme ultraviolet light emitted from high-density high-temperature plasma,
In an extreme ultraviolet light source device having an extreme ultraviolet light extraction unit that extracts extreme ultraviolet light through the condensing optical means,
A rare gas supply means for introducing a rare gas;
A switching means for switching between a raw material supply from the raw material supply means and a rare gas supply from the rare gas supply means into the container,
An extreme ultraviolet light source device, wherein rare gas plasma is generated in the container, and deposits deposited in the container are removed when the raw material is heated and excited to generate high-density and high-temperature plasma. 2. The extreme according to claim 1, wherein the raw material supply flow path from the raw material supply means and the rare gas supply flow path from the rare gas supply means are connected to each other in the container independently of each other. Ultraviolet light source device. 3. The extreme according to claim 1, wherein a light shielding means for shielding the extreme ultraviolet light emitted from the high-density and high-temperature plasma from being output to the outside is provided in the container. Ultraviolet light source device. The light shielding means divides the inside of the container into a first space in which the raw material is heated and excited to generate a high-density and high-temperature plasma and a second space including the condensing optical means when extreme ultraviolet light is shielded. The extreme ultraviolet light source device according to claim 3, wherein the extreme ultraviolet light source device is provided. 4. A power source for the raw material supply means, preliminary ionization means and heating excitation means, a rare gas supply means, and a control means for controlling the operation of the switching means. Item 5. The extreme ultraviolet light source device according to any one of Items 4 to 5. 6. The extreme ultraviolet light source device according to claim 1, wherein the extreme ultraviolet light emitting species is either tin (Sn) or lithium (Li). . 6. The extreme ultraviolet light source apparatus according to claim 1, wherein the raw material is stannane (SnH ₄ ). The extreme ultraviolet light source device according to any one of claims 1, 2, 3, 4, 5, 6 and 7, wherein the rare gas is xenon (Xe). Hydrogen gas supply means is further provided,
The switching means switches the raw material supply from the raw material supply means into the container to the rare gas supply from the rare gas supply means, and supplies the rare gas into the container.
9. The switch according to any one of claims 1, 2, 3, 4, 5, 6, 7 or 8, wherein the hydrogen gas is supplied from the hydrogen gas supply means into the container together with the rare gas. The extreme ultraviolet light source device described in 1. Extreme ultraviolet light source that collects and extracts extreme ultraviolet light radiated from high-density and high-temperature plasma generated by heating and exciting raw materials containing extreme ultraviolet radiation species and / or compounds containing extreme ultraviolet radiation species in a container A deposit removal method for removing deposits in a container in an apparatus, comprising:
While the generation of extreme ultraviolet light is suspended, the raw material supply into the container is switched to the rare gas supply to supply the rare gas,
An extreme ultraviolet light source characterized in that a rare gas plasma discharge is generated in a container, and deposits deposited in the container generated when the high-density and high-temperature plasma is generated are removed by the rare gas plasma. A method for removing deposits in an apparatus. 11. The extreme ultraviolet light source according to claim 10, wherein when the generation of the extreme ultraviolet light is stopped, the supply of the raw material into the container is stopped, the inside of the container is evacuated, and then the rare gas is supplied into the container. A method for removing deposits in an apparatus. When supplying a rare gas into the container, the container is divided into a space that has been heated and excited to generate extreme ultraviolet light and a space that has been focused,
12. The method for removing deposits in an extreme ultraviolet light source device according to claim 10, wherein a plasma discharge of a rare gas is generated in the space where the heating and excitation are performed. 2. When switching between the raw material supply from the raw material supply means and the rare gas supply from the rare gas supply means, one supply flow rate is gradually decreased and the other supply flow rate is gradually increased. The deposit removal method in the extreme ultraviolet light source device in any one of Claim 10 or Claim 12. 14. The device according to claim 10, wherein the deposit is judged to have reached a predetermined amount when the number of occurrences of extreme ultraviolet light reaches a predetermined number, and a warning signal is output. The deposit removal method in the extreme ultra violet light source device described in 1. The deposit amount of the deposit is calculated by monitoring, and when the calculated deposit amount reaches a predetermined value, it is determined that the deposit has reached a predetermined amount, and a warning signal is output. , 11, 12 or the method for removing deposits in an extreme ultraviolet light source device according to claim 13.

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