JP2009026935A - Pre-treatment and cleaning method for condensing reflector and extreme ultraviolet light source device provided with condensing reflector - Google Patents

Abstract

To provide a pre-processing and cleaning method for a condensing reflector and an extreme ultraviolet light source device capable of completely removing contaminants deposited on the light reflecting surface of the condensing reflector.
A discharge gas is supplied to a plasma generation unit, and a high voltage pulse voltage is applied from a high voltage pulse generation unit to a first main discharge electrode and a second main discharge electrode. Thereby, high temperature plasma is generated and extreme ultraviolet light having a wavelength of 13.5 nm is emitted. This extreme ultraviolet light is collected by the condensing reflecting mirror 4 and emitted from the EUV light extraction unit 5. The debris generated by the generation of the high temperature plasma forms a contaminant layer on the light reflecting surface of the condensing reflector 4, and in order to completely remove this, in the present invention, the contaminant layer is collected before the contaminant layer is formed. A cleaning gas constituent material is adhered to the surface of the light reflecting mirror. Thereby, the contaminant can be removed almost completely by circulating the cleaning gas from the cleaning gas supply nozzle 25.
[Selection] Figure 1

Description

As an exposure light source for the next generation semiconductor integrated circuit, an extreme ultraviolet light source device (hereinafter also simply referred to as EUV light source device) that emits extreme ultraviolet light (hereinafter also simply referred to as EUV light) is expected.
The present invention relates to a pretreatment and cleaning method for a condensing reflector used in the extreme ultraviolet light source device and an extreme ultraviolet light source device including such a condensing reflector.

As the semiconductor integrated circuit is miniaturized and highly integrated, an improvement in resolution is required for an exposure apparatus for manufacturing the semiconductor integrated circuit. In order to improve the resolution, it is common to use an exposure light source that emits light of a short wavelength. An excimer laser device is used as an exposure light source that emits light having a short wavelength, but an extreme ultraviolet light source device that emits extreme ultraviolet light having a wavelength of 13.5 nm as an alternative light source for next-generation exposure. Development is underway.
As one method for generating extreme ultraviolet light, there is a method in which high temperature plasma is generated by heating and exciting a discharge gas including an extreme ultraviolet light radiation source, and the extreme ultraviolet light emitted from the plasma is taken out. Extreme ultraviolet light source devices that employ such a method are roughly classified into an LPP (Laser Produced Plasma) method and a DPP (Discharge Produced Plasma) method, depending on the method of generating high-temperature plasma.

The LPP type extreme ultraviolet light source device irradiates a target made of raw materials including an extreme ultraviolet light source with laser light, generates high-temperature plasma by laser ablation, and uses the extreme ultraviolet light emitted therefrom. To do.
The extreme ultraviolet light source device of the DPP system generates high temperature plasma by discharge by applying a high voltage between electrodes supplied with a discharge gas including an extreme ultraviolet light radiation source, and emits extreme ultraviolet light emitted therefrom. Is to be used. Such a DPP type extreme ultraviolet light source device is advantageous in that the light source device can be made smaller and the power consumption of the light source system is smaller than that of the LPP type extreme ultraviolet light source device. Therefore, practical application is expected.

Xe (xenon) ions having about 10 valences are known as raw materials for generating the high-temperature plasma, but Li (lithium) ions and Sn (tin) are used as raw materials for radiating stronger extreme ultraviolet light. Ions are attracting attention.
For example, Sn has a high output because the extreme ultraviolet light conversion efficiency given by the ratio of the electrical input required for generating high temperature plasma and the radiation intensity of extreme ultraviolet light with a wavelength of 13.5 nm is several times larger than Xe. It is expected as a radiation source for obtaining extreme ultraviolet light. For example, as shown in Patent Document 1, development of an extreme ultraviolet light source device using, for example, SnH ₄ (stannane) gas as an extreme ultraviolet light radiation source has been advanced.

Hereinafter, a conventional DPP type extreme ultraviolet light source device will be described.
(1) Structure of Conventional Extreme Ultraviolet Light Source Device FIG. 7 shows the configuration of a DPP extreme ultraviolet light source device.
As shown in FIG. 7, the DPP type extreme ultraviolet light source device includes a first chamber in which a plasma generation unit 2 including a first main discharge electrode 2a, a second main discharge electrode 2b, and an insulating material 2c is accommodated. 1a and a second chamber 1b in which the condenser reflector 4 is accommodated.
In the first chamber 1a, for example, a ring-shaped first main discharge electrode (cathode) 2a and a ring-shaped second main discharge electrode (anode) 2b are arranged with a ring-shaped insulating material 2c interposed therebetween. Is done. The first main discharge electrode 2a and the second main discharge electrode 2b are made of a refractory metal such as tungsten, molybdenum, or tantalum. The insulating material 2c is made of, for example, silicon nitride, aluminum nitride, diamond, or the like. The first main discharge electrode 2 a and the second main discharge electrode 2 b are connected to the high voltage pulse generator 11.

The ring-shaped first main discharge electrode 2a, the ring-shaped second main discharge electrode 2b, and the ring-shaped insulating material 2c are arranged so that the respective through holes are positioned substantially on the same axis to form a communication hole. is doing. When pulse power is supplied between the first main discharge electrode 2a and the second main discharge electrode 2b to generate discharge, high-temperature plasma is generated in the communication hole or in the vicinity of the communication hole.
Supply of pulse power between the first main discharge electrode 2a and the second main discharge electrode 2b is performed by a high voltage pulse generator 11 connected to the first main discharge electrode 2a and the second main discharge electrode 2b. Made.
The first main discharge electrode 2a, the second main discharge electrode 2b, and the insulating material 2c constitute a DPP-type plasma generation unit 2. There are various examples of the DPP type extreme ultraviolet light source device other than the one shown in FIG. 7, but refer to Non-Patent Document 1 for that. In addition, you may provide the preionization means to preionize the raw material containing the extreme ultraviolet light radiation seed | species supplied in the chamber as needed.

The second chamber 1b is provided with a condensing reflecting mirror 4 that condenses extreme ultraviolet light. The condensing reflecting mirror 4 includes, for example, a plurality of spheroid shapes, rotating paraboloid shapes, or Walter type mirrors having different diameters. 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 extreme ultraviolet light with an oblique incident angle of 0 ° to 25 ° can be reflected well.
Further, in the second chamber 1b, metal powder or the like generated by sputtering a metal (for example, a discharge electrode) in contact with the high temperature plasma in the space between the plasma generator 2 and the condensing reflector 4 A foil trap 3 is installed for trapping the debris and the debris caused by the radioactive species and reducing the kinetic energy and passing the EUV light.

The foil trap 3 includes two rings, an inner ring and an outer ring, which are concentrically arranged, and a plurality of thin plates which are radially arranged with both sides supported by the two rings. By finely dividing the space where the plate is placed, the pressure in that portion is raised, the kinetic energy of the debris is lowered, and the plate or ring captures it. On the other hand, when viewed from the high temperature plasma, the foil trap 3 can only see the thickness of the plate except for two rings, and most of the extreme ultraviolet light passes through.
In the second chamber 1b, a gas curtain is formed in the space between the first main discharge electrode 2a and the foil trap 3 in order to further reduce the amount of debris reaching the condenser reflector 4. For this reason, a gas curtain nozzle 7a inserted from an opening formed in the side wall of the second chamber 1b is arranged inside the second chamber 1b so as to supply a gas that does not possibly attenuate extreme ultraviolet light. The gas supply unit 7 is connected to the gas curtain nozzle 7a. When the gas curtain is formed, a space having a high gas pressure is locally formed with respect to the debris scattered toward the condensing reflecting mirror 4. Accumulation of debris can be suppressed.
Further, a gas exhaust unit 8 for adjusting the pressure inside the plasma generating unit 2 and exhausting the inside of the chamber is connected to a gas exhaust port 8a provided in the second chamber 1b. The gas exhaust unit 8 has gas exhaust means (not shown) such as a vacuum pump.

Further, the control unit 12 provided in the DPP type extreme ultraviolet light source apparatus shown in FIG. The gas supply unit 7 and the gas exhaust unit 8 are controlled.
For example, when the control unit 12 of the extreme ultraviolet light source apparatus receives a light emission command signal from the control unit 13 of the exposure machine, the control unit 12 controls the discharge gas supply unit 7 to discharge the discharge gas into the plasma generation unit in the chamber 1b. Supply.
Further, based on pressure data from a pressure monitor (not shown) provided in the second chamber 1b, the discharge gas supply amount from the discharge gas supply unit 6 is controlled so that the inside of the plasma generation unit 2 has a predetermined pressure. In addition, the exhaust amount by the gas exhaust unit 8 is controlled. Thereafter, in order to generate high-temperature plasma that emits extreme ultraviolet light, the high-voltage pulse generator 11 is controlled to supply power between the first main discharge electrode 2a and the second main discharge electrode 2b.

(2) Radiation of extreme ultraviolet light Radiation of extreme ultraviolet light is performed as follows.
A discharge gas is introduced into the first chamber 1a through the raw material introduction tube 6a connected to the second main discharge electrode 2b side from the discharge gas supply unit 6. The discharge gas is for efficiently forming a radiation source that emits extreme ultraviolet light having a wavelength of 13.5 nm in the plasma generation unit 2, and is, for example, stannane (SnH ₄ ).
The SnH ₄ introduced into the plasma generation unit 2 passes through the communication hole formed by the ring-shaped first main discharge electrode 2a, second main discharge electrode 2b, and insulating material 2c, and the second It flows to the chamber 1b side and reaches the gas discharge port 8a. The discharge gas that has reached the gas discharge port 8 a is exhausted by the gas exhaust unit 8.

Here, the pressure inside the plasma generation unit 2 is adjusted to 1 to 20 Pa by controlling the exhaust speed of the gas exhaust unit 8.
This pressure adjustment is performed as follows, for example. First, the control unit 12 receives pressure data inside the plasma generation unit 2 output from a pressure monitor (not shown). The control unit 12 controls the discharge gas supply unit 6 and the gas exhaust unit 8 based on the received pressure data to adjust the supply amount and the exhaust amount of SnH ₄ into the chamber 1a, whereby the plasma generation unit 2 is controlled. The pressure is adjusted to a predetermined pressure.

In a state where the discharge gas flows through the communication hole formed by the ring-shaped first main discharge electrode 2a, the ring-shaped second main discharge electrode 2b, and the ring-shaped insulating material 2c, the second main A high voltage pulse voltage of about +20 kV to −20 kV is applied from the high voltage pulse generator 11 between the discharge electrode 2b and the first main discharge electrode 2a. As a result, creeping discharge is generated on the surface of the insulating material 2c, whereby the first main discharge electrode 2a and the second main discharge electrode 2b are substantially short-circuited, and the first main discharge A large pulse current flows between the electrode 2a and the second main discharge electrode 2b.
Thereafter, extreme ultraviolet light having a wavelength of 13.5 nm is radiated from the high-temperature plasma generated by the discharge gas generated inside the plasma generation unit 2 by Joule heating due to the pinch effect. That is, the extreme ultraviolet light emitted from the DPP type extreme ultraviolet light source device becomes pulsed light. The extreme ultraviolet light emitted from the plasma generation unit 2 is collected by a condensing reflecting mirror 4 provided in the second chamber 1b, and is an exposure machine side optical system not shown from the EUV light extraction unit 5. It is emitted to the irradiation unit.

Here, the DPP extreme ultraviolet light source device may be provided with a preionization means for preionizing the raw material including the extreme ultraviolet light radiation source supplied into the chamber when a discharge is generated in the chamber. When generating extreme ultraviolet light, the pressure of the plasma generation unit 2 is adjusted to 1 to 20 Pa, for example. 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 in a situation where the discharge is difficult to occur, it is desirable to perform preionization.
For reference, an example in which a preionization unit is combined with a DPP type extreme ultraviolet light source device is disclosed in, for example, Patent Document 2.

JP 2004-279246 A JP 2003-218025 A JP 2006-529057 A “Current Status and Future Prospects of EUV (Extreme Ultraviolet) Light Source Research for Lithography”

According to such an extreme ultraviolet light source device, the following problems actually occurred.
That is, as the usage time of the extreme ultraviolet light source device elapses, contaminants accumulate on the light reflecting surface of the condensing reflector 4 and a contaminant layer is formed on the light reflecting surface, so that the extreme on the light reflecting surface is increased. As the reflectivity of the ultraviolet light is reduced, there is a problem that the intensity of the extreme ultraviolet light condensed at the intermediate condensing point of the extreme ultraviolet light source device is reduced.
The cause of the formation of the pollutant layer on the light reflecting surface of the condensing reflector 4 is not clear, but is made of a metal powder produced by sputtering a metal (for example, a discharge electrode) in contact with the high temperature plasma. It is considered that debris and debris caused by the radioactive species contained in the discharge gas are deposited on the light reflecting surface. Below, the mechanism by which the contaminant layer is formed on the light reflecting surface of the condensing reflector 4 will be described.

In the extreme ultraviolet light source device described above, the extreme ultraviolet light source is made of stannane (SnH ₄ ), lithium (Li), or the like, and the first and second main discharge electrodes 2a and 2b are tungsten (W), thallium ( Th), copper (Cu), etc., insulating material 2c is made of silicon nitride (SiN), silicon carbide (SiC), etc., foil trap 3 is made of molybdenum (Mo), etc., and these substances form a pollutant layer. Can be a factor.
That is, when the discharge plasma formed between the first and second main discharge electrodes 2a and 2b expands, SnH ₄ which is an extreme ultraviolet light radiation source is decomposed into Sn and H, and Sn generated is collected. By being driven into the light reflecting surface of the light reflecting mirror 4 at a high speed, a contaminant layer made of Sn is formed on the light reflecting surface of the condensing reflecting mirror 4. On the other hand, there is SnH ₄ that is not decomposed into Sn and H even if it is affected by the expansion of the discharge plasma. In this case, SnH ₄ floats toward the vicinity of the light reflecting surface of the condenser reflector. In some cases, Sn is deposited on the light reflecting surface by being decomposed into Sn and H on the light reflecting surface.

Further, W, Th, Cu, and the insulating material 2c constituting the electrodes 2a and 2b are constituted by erosion caused by discharge plasma formed between the first and second main discharge electrodes 2a and 2b or a thermal load caused by discharge. SiN, SiC, and Mo constituting the foil trap 3 are driven onto the light reflecting surface of the condensing reflecting mirror 4 at a high speed, so that these contaminants are formed on the light reflecting surface of the condensing reflecting mirror 4. A contaminant layer is formed.
As described above, between the plasma generation unit 2 and the condenser reflector 4, debris such as metal powder or debris caused by radioactive species contained in the discharge gas is captured, or these kinetic energy A foil trap 3 is installed for reducing EUV and allowing EUV light to pass through. However, in practice, it is difficult to completely remove the above-described debris with the foil trap 3, and contamination of the light reflecting surface of the condensing reflecting mirror 4 is an unavoidable problem.

Patent Document 3 describes a method of cleaning contamination of an optical element by reacting a cleaning gas with a contaminant (debris) deposited on the optical element. By carrying out this method, it is expected that contaminants deposited on the light reflecting surface of the condensing reflector 4 can be completely removed.
However, actually, even if the cleaning method disclosed in Patent Document 3 is performed, the contaminants on the light reflecting surface cannot be completely removed. The inventors of the present invention can completely remove the contamination of the light reflecting surface by simply reacting the cleaning gas with the contaminants deposited on the light reflecting surface of the condenser reflector by performing an experiment described later. Make sure you can't.
As described above, the conventional cleaning method cannot completely remove the contaminants on the light reflecting surface of the condenser reflector. The present invention has been made based on such circumstances, and it is possible to completely remove the contaminants deposited on the light reflecting surface of the converging reflector with the passage of time of use of the extreme ultraviolet light source device. An object of the present invention is to provide a pre-processing and cleaning method for a condensing reflecting mirror and an extreme ultraviolet light source device.

In order to solve the above problems, the present inventors have intensively studied, and as a result, before the contaminant layer is formed on the surface of the converging reflector, the cleaning gas structure is formed on the light reflecting surface constituting material of the condensing mirror By performing a pretreatment process to attach substances, even if a contaminant layer is formed on the surface of the condenser reflector, it is possible to effectively remove accumulated contaminants by cleaning with a cleaning gas or the like. I found.
The reason for this is not clear, but is considered as follows.
FIG. 2 is a diagram conceptually illustrating the reason why the effect of the present invention is expected. FIG. 2A is a conceptual diagram schematically showing a reaction between a conventional contaminant layer and a cleaning gas, and FIG. 2B is a light reflecting surface constituent material in the light reflecting surface of the light collecting mirror of the present invention. It is a conceptual diagram which shows roughly reaction of a layer and cleaning gas. FIG. 2 shows an example in which the radioactive species contained in the discharge gas is tin (Sn) and the cleaning gas is chlorine (Cl).

As shown in FIG. 2A, in the conventional condenser reflector, with the passage of the usage time of the extreme ultraviolet light source device, ruthenium (Ru) which is a light reflecting surface constituent material and Sn which is a contaminant. Reacts with each other to form a (Ru—Sn) layer, and further deposits Sn to form a Sn layer on the Ru—Sn layer. When the cleaning gas (Cl) is circulated from the light reflecting surface side to the condensing reflector in this state, the Sn layer and Cl react to finally produce tin chloride (SnCl ₄ ), whereby Sn. Sn in the layer can be removed. The generated gaseous SnCl ₄ is exhausted to the outside of the chamber by the gas exhaust unit.
However, Cl introduced as a cleaning gas has a stronger bond strength between Ru and Sn than the reaction strength between Sn and Cl, so it is difficult to react with Sn in contact with Ru. Can easily react to produce and remove SnCl ₄ , but Sn in contact with Ru is difficult to remove. As described above, conventionally, it has not been possible to completely remove the contaminant layer deposited on the light reflecting surface of the condensing reflector with the passage of the use time of the extreme ultraviolet light source device.

On the other hand, as shown in FIG. 2 (B), in the light collecting / reflecting mirror of the present invention, the light reflecting surface of the light collecting / reflecting mirror is preliminarily treated with a cleaning gas to thereby obtain the light reflecting surface. Cl, which is a cleaning gas constituent material, adheres to the Ru layer, which is a constituent material layer. When an extreme ultraviolet light source device equipped with this condensing reflector is used, an Sn layer is formed on the Ru layer made of the light reflecting surface constituent material even if Sn is deposited on the light reflecting surface over time. In other words, an Sn layer is only formed on Cl.
Therefore, when the cleaning gas (Cl) is circulated from the light reflecting surface side to the condenser reflector in this state, Sn and Cl react to generate tin chloride (SnCl ₄ ), and Sn disappears. The generated SnCl ₄ is exhausted to the outside of the chamber by the exhaust unit.
According to experiments, it has been found that the effect of the present invention can be expected if a cleaning gas constituent material such as Cl is attached to the light reflecting surface of the condenser reflector at least 0.2 nm in thickness.

Based on the above, the present invention solves the above problems as follows.
(1) In a condensing reflector for condensing extreme ultraviolet light emitted from an extreme ultraviolet light emitting species of metal or metal compound at a predetermined position, before a contaminant layer is formed on the surface of the condensing reflector Then, a pretreatment step of attaching a cleaning gas constituent material to the light reflecting surface constituent material of the condenser mirror is performed.
(2) After the pretreatment step (1) above, after the contaminant layer is formed on the surface of the condenser reflector, a posttreatment step is performed to remove the contaminant with a cleaning gas.
(3) In the above (1) and (2), chlorine (Cl) is used as the cleaning gas constituent material. At that time, it is preferable to attach chlorine (Cl) to the light reflecting surface constituting material by 0.2 mm or more.
(4) In the above (1) and (2), the light reflecting surface constituting material is ruthenium (Ru). (5) In the above (1) and (2), the contaminant layer is made of tin (Sn) or a tin (Sn) compound contained in the discharge gas.
(6) In the above (2), the pretreatment step and the posttreatment step are performed in the same container.
(7) A chamber having a light outlet, a raw material supply means for supplying a raw material containing an extreme ultraviolet light emitting species of metal or metal compound to the chamber, and heating and exciting the extreme ultraviolet light emitting species supplied in the chamber A plasma generating unit for generating high temperature plasma, a condensing reflecting mirror for condensing extreme ultraviolet light at a predetermined position, and a cleaning gas for removing a contaminant layer deposited on the surface of the condensing reflecting mirror An extreme ultraviolet light source device comprising: a cleaning gas supply means that supplies a light reflecting surface that reflects extreme ultraviolet light on the condensing reflector, and chlorine is added to the light reflecting surface by a pretreatment with a cleaning gas. A compound is generated.
(8) In the above (7), a shutter is provided in the chamber to partition the plasma generation unit and the chamber in which the condenser reflector is accommodated.
(9) In a condensing reflector having a light reflecting surface that reflects extreme ultraviolet light, a cleaning gas constituent material is adhered to the light reflecting surface constituent material.

According to the present invention, the following effects can be obtained.
(1) Since the cleaning gas constituent material is attached to the light reflecting surface constituent material layer constituting the light reflecting surface of the condensing reflector, it is removed on the light reflecting surface as described above. The possibility of forming a contaminant layer that cannot be removed can be eliminated.
For this reason, it is expected that the contaminant layer inevitably formed on the light reflecting surface of the condensing reflector as the plasma generation time elapses can be almost completely removed by the cleaning process.
(2) When the light reflecting surface of the condensing reflector is made of ruthenium (Ru), the light reflecting surface is not deteriorated by reacting with a halogen gas such as chlorine (Cl). There is no possibility that the reflectance of extreme ultraviolet light will decrease.
(3) If the pre-processing step and the post-processing step are performed in the same container, the pre-processing step can be performed using the chamber of the extreme ultraviolet light source device as it is without preparing a special device. it can.
In addition, by providing a shutter that divides the plasma generation unit and the chamber that stores the condenser reflector, the main discharge electrode and the cleaning gas react in the pre-processing step and the post-processing step, and the main discharge electrode deteriorates. Or the cleaning gas flows out of the chamber, so that there is no fear that the precision instrument mounted on the exposure machine is corroded by the cleaning gas.

FIG. 1 is a cross-sectional view schematically showing the configuration of an extreme ultraviolet light source device according to a first embodiment of the present invention. FIG. 1 shows a configuration when the present invention is applied to the DPP-type extreme ultraviolet light source device shown in FIG. 7, and the same parts as those in FIG. The cleaning gas constituent material is attached to the light reflecting surface constituent material layer constituting the light reflecting surface 4, the first, second and third gates 21 to 23, the cleaning gas supply unit 24, and the cleaning gas supply The configuration is the same as that shown in FIG. 7 except that the nozzle 25 and the like are provided.
3 is an enlarged cross-sectional view of the main part of the condenser reflector 4 arranged in the extreme ultraviolet light source device shown in FIG. 1, and FIG. 4 shows the cleaning gas supply nozzle 25 from the direction in which the cleaning gas blows out. Schematic view when seen.

As described above, the extreme ultraviolet light source device according to the present embodiment fills the discharge gas introduced into the plasma generation unit 2 made of the first main discharge electrode 2a, the second main discharge electrode 2b, and the insulating material 2c. The first chamber 1a, the plasma generation unit 2 connected to the first chamber 1a, and the second chamber 1b in which the condenser reflector 4 and the foil trap 3 are accommodated. The second chamber 1b is continuous with the main body portion 10 in which the foil trap 3 and the condenser reflector 4 are accommodated, and has a step with respect to the main body portion 10 because it has a smaller diameter than the main body portion 10. The connecting part 10a is connected to the plasma generating part 2.
In the extreme ultraviolet light source device of the present invention, the discharge gas supply unit 6 side of the plasma generation unit 2 with the plasma generation unit 2 interposed therebetween is referred to as a first chamber 1a, and the foil is more than the plasma generation unit 2. The side of the trap 3 and the condenser reflector 4 is referred to as a second chamber 1b.

A ring-shaped second main discharge electrode 2b is connected to the first chamber 1a having a connection port of the discharge gas supply unit 6. A discharge gas supply unit 6 is connected to the first chamber 1a via a raw material introduction tube 6a.
As described above, the ring-shaped first main discharge electrode 2a, the ring-shaped second main discharge electrode 2b, and the ring-shaped insulating material 2c are arranged so that the respective through holes are positioned substantially coaxially. When pulse power is supplied between the first main discharge electrode 2a and the second main discharge electrode 2b to generate a discharge, high temperature plasma is generated in the communication hole or in the vicinity of the communication hole.
Supply of pulse power between the first main discharge electrode 2a and the second main discharge electrode 2b is performed by a high voltage pulse generator 11 connected to the first main discharge electrode 2a and the second main discharge electrode 2b. Made.

A foil trap 3 that captures debris scattered from the plasma generation unit 2 and a condensing reflector 4 that collects extreme ultraviolet light are disposed in the second chamber 1 b having the EUV light extraction port 5.
Further, as described above, the gas curtain nozzle 7a inserted from the opening formed in the side wall of the second chamber 1b is arranged inside the second chamber 1b, and there is no risk of attenuating extreme ultraviolet light. A gas supply unit 7 is connected to the gas curtain nozzle 7a. When the gas curtain is formed, the debris is decelerated and it is possible to suppress the debris from accumulating on the condenser reflector 4.
Furthermore, the pressure of the discharge gas containing the extreme ultraviolet light radiation species introduced into the plasma generator 2 is optimal for the second chamber 1b for adjusting the pressure inside the plasma generator 2 and exhausting the chamber. Therefore, a gas exhaust port 8 a communicating with the gas exhaust unit 8 is provided. Further, the control unit 12 controls the high voltage pulse generation unit 11, the discharge gas supply unit 6, the gas supply unit 7, and the gas exhaust unit 8 based on a light emission command signal from the control unit 13 of the exposure machine.
About the above structure, it is common with the conventional extreme ultraviolet light source device shown in FIG.

The condensing reflector 4 according to the extreme ultraviolet light source device of the present invention has ruthenium (Ru), molybdenum (Mo), and rhodium (Rh) on the reflecting surface side of the base material having a smooth surface made of nickel (Ni) or the like. ) And the like are densely coated to form a plurality of light reflecting surfaces nested so that extreme ultraviolet light having an oblique incident angle of 0 ° to 25 ° can be favorably reflected, as shown in FIG. The cleaning gas constituent material adheres to the light reflecting surface constituting material layer constituting the light reflecting surface. That is, as shown in the figure, the cleaning gas constituent material 4b adheres to the surface side of the light reflecting surface constituent material 4a such as ruthenium (Ru) on the surface of the condenser reflector 4.
The cleaning gas constituent material 4b is not trapped by the gas curtain or the foil trap 3, for example, the material constituting the extreme ultraviolet light source or the main discharge electrode adheres directly to the light reflecting surface of the condenser reflector. In order to prevent this, it is attached to the light reflecting surface constituting material. Specifically, the cleaning gas is, for example, a halogen gas.

The cleaning gas constituent material is not limited to the type of cleaning gas, but especially ruthenium (Ru) constituting the light reflecting surface of the condensing reflector 4 when it is composed of chlorine (Cl). There is an advantage that it does not react so much and there is little fear of deteriorating the reflectance of the extreme ultraviolet light on the light reflecting surface.
Such a cleaning gas constituent material 4b adheres to the light reflecting surface constituent material of the condensing reflector 4 as follows, for example.
Prior to mounting the condensing / reflecting mirror 4 on the extreme ultraviolet light source device, the condensing / reflecting mirror 4 is disposed in a pretreatment container having a halogen gas atmosphere such as Cl.
Introducing Cl at a flow rate of 500 sccm, placing the condensing reflector in a pretreatment container in which the Cl pressure becomes 2.0 × 10 ³ pa for 1 minute, and constituting the light reflecting surface of the condensing reflector 4 A cleaning gas constituent 4b is attached to 4a.
In this manner, the extreme ultraviolet light source device is completed by mounting the condensing reflecting mirror 4 having the light reflecting surface to which the cleaning gas constituent material 4b is attached in the second chamber 1b.
As will be described later, after the extreme reflecting light source device is completed by mounting the condensing reflecting mirror 4 to which the cleaning gas constituent material is not attached in the second chamber 1b, the inside of the second chamber 1b is cleaned. By setting the gas atmosphere, the cleaning gas constituent material 4b can be attached to the light reflecting surface constituent material 4a of the condensing reflector 4.

Here, in the extreme ultraviolet light source device according to the present invention, as the process (plasma generation process) in which discharge is generated between the first and second main discharge electrodes 2a and 2b elapses, the discharge gas A part of the material constituting the main discharge electrode in contact with the extreme ultraviolet light radiation source or the high temperature plasma contained therein is not captured by the gas curtain or the foil trap 3 on the light reflecting surface of the condensing reflecting mirror 4. As a result, a contaminant layer consisting of these contaminants is formed.
This contaminant layer is deposited on the cleaning gas constituent material 4b attached to the light reflecting surface constituent material 4a of the condenser reflector 4.
In order to remove such a contaminant layer, the cleaning gas is directly blown onto the second chamber 1 b against the cleaning gas supply unit 24 that supplies the cleaning gas and the light reflecting surface of the condensing reflector 4. A cleaning gas supply nozzle 25 is provided. The cleaning gas supply nozzle 25 includes a delivery part 24a having a cylindrical shape connected to the cleaning gas supply unit 24, and a blowing part 25a connected to the distal end side of the delivery part 24a.

FIG. 4 is a schematic view when the cleaning gas supply nozzle 25 is viewed from the direction in which the cleaning gas blows out.
The blowing portion 25a passes through the center point of the annular frame body portion 25b and the annular frame body portion 25b, and extends radially from the center point toward the inner periphery of the frame body portion 25b. It consists of a plurality of cylindrical frame portions 25c fixed to the inner periphery. In each of the cylindrical frame portions 25c, a plurality of outlets 25d for blowing out the cleaning gas are formed at equal intervals along the longitudinal direction of the frame portion 25c. According to such a blowout part 25a, each of the blowout openings 25d formed in each of the frame parts 25c is arranged side by side on a plurality of concentric circles formed starting from the center of the frame part 25b.

Such a cleaning gas supply nozzle 25 condenses light during the plasma generation time so that the radiation intensity at the intermediate condensing point does not decrease by shielding the condensed light emitted from the condensing reflecting mirror 4. It is necessary not to be disposed on the optical path connecting the reflecting mirror 4 and the extreme ultraviolet light outlet 5.
Therefore, in the process of stopping the generation of plasma and cleaning the light reflecting surface of the condenser reflector 4, the cleaning gas supply nozzle 25 is blown out from each of a plurality of concentric circles formed by each of the blowing ports 25d. The cleaning gas is disposed in the light emitting direction of the condensing reflector 4 so as to be directly blown toward each of the plurality of light reflecting surfaces formed in a nested manner. It is possible to move inside the chamber 1b by a predetermined nozzle driving means 24b so as to retreat from the optical path connecting the extreme ultraviolet light outlet.

When cleaning the light reflecting surface of the condensing reflector 4, the first and second main discharge electrodes 2a and 2b react with a cleaning gas such as a halogen gas by the reaction of the first and second main discharge electrodes 2a and 2b. In addition, it is necessary to avoid the possibility that the second main discharge electrodes 2a and 2b are deteriorated, or that the precision instrument mounted in the exposure machine connected to the chamber 1b is eroded by the halogen gas. Therefore, the second chamber 1b includes the first to third gates 21 to 23 and the first to third gates for sealing the inside of the second chamber 1b when the condenser mirror 4 is cleaned. Gate valves 21a to 23a are provided.
The first to third gates 21 to 23 are provided at three locations in the vicinity of the connecting portion 10 a connected to the plasma generating portion 2, the extreme ultraviolet light outlet 5, and the gas exhaust port 8 a leading to the gas exhaust unit 8. As will be described later, the first and third gate valves 21a to 23a are opened and closed before and after cleaning the light reflecting surface of the condenser reflector 4.

According to the extreme ultraviolet light source device having such a configuration, as the plasma generation time elapses, in order to remove the contaminant layer deposited on the light reflecting surface of the converging reflector, the light reflection is performed as follows. The surface is cleaned.
In the following, when the cleaning gas constituent material is attached in advance to the light reflecting surface of the condensing reflecting mirror (the cleaning gas constituent material is placed on the light reflecting surface of the condensing reflecting mirror before mounting in the extreme ultraviolet light source device). When attached: First method) and when a cleaning gas constituent material is attached to the light reflecting surface of the condensing reflector afterwards (after the condensing reflector is mounted on the extreme ultraviolet light source device, Both the case where the cleaning gas constituent material is deposited on the light reflecting surface of the light reflecting mirror: the second method) will be described.
In the following, the “pretreatment step” means a step of attaching a cleaning gas constituent material to the light reflecting surface constituent material of the condensing reflector, and the “post treatment step” means that the plasma generation time has elapsed. Along with this, it means a step of removing the contaminant layer deposited on the light reflecting surface of the condenser reflector.

A. First Method The first method is to perform a post-processing step using a cleaning gas on the premise that the pre-processing step is performed at a stage before the condenser reflector is mounted on the extreme ultraviolet light source device. It is the cleaning method of the condensing reflective mirror characterized. The method and conditions for attaching the cleaning gas constituents are as described above.
That is, the condensing reflector 4 is installed in a pretreatment container having a halogen gas atmosphere such as Cl, Cl is introduced into the container at a predetermined flow rate (for example, 500 sccm), and a predetermined pressure (for example, in the container) 2.0 × 10 ³ pa), and the condensing reflector 4 is disposed for a predetermined time (for example, 1 minute), so that the cleaning gas constituent material 4b is attached to the light reflecting surface constituent material 4a of the condensing reflector 4.
The light reflection surface of the condensing reflector 4 has an allowable reflectance range for extreme ultraviolet light. In the plasma generation process, the thickness of the contaminant layer deposited on the light reflecting surface of the condenser reflector 4 is generally increased in proportion to the plasma generation time. Therefore, when the plasma generation time reaches a certain time, it is necessary to perform a post-treatment process using a cleaning gas.

The post-processing process is performed as follows.
(1) First, a discharge stop signal is transmitted from the control unit 12 to the high voltage pulse generator 11 based on the discharge stop signal received from the exposure apparatus. The high voltage pulse generator 11 stops the application of the high voltage pulse voltage to the first and second main discharge electrodes 2a and 2b by receiving the discharge stop signal from the controller 12, and discharges in the plasma generator 2 Stop.
Further, the control unit 12 transmits a discharge gas stop signal to the discharge gas supply unit 6. The discharge gas supply unit 6 that has received the discharge gas stop signal stops the supply of the discharge gas to the plasma generator 2.
(2) With the supply of the discharge gas to the plasma generation unit 2 stopped, the control unit 12 applies a gas supply unit 7 for forming a gas curtain in the space between the foil trap 3 and the plasma generation unit 2. To send a gas stop signal. The gas supply unit 7 that has received the gas stop signal stops the supply of gas.

(3) Next, each of the first and second gate valves 21a and 22a receives the gate closing signal transmitted from the control unit, thereby opening the first and second gates. 21 and 22 are driven to close the connecting portion 10a of the second chamber 1b and the EUV light extraction port 5. Thereby, the gas for forming the discharge gas and the gas curtain containing the extreme ultraviolet light radiation species remaining in the second chamber 1b and the gas exhaust unit 8 which is always in operation from the time of plasma generation are chambered. It is discharged outside.
(4) In this state, the control unit 12 transmits a drive signal to the nozzle drive unit 24b. The nozzle driving means 24b that has received the drive signal drives the cleaning gas supply nozzle 25, and the cleaning gas blown out from each of the plurality of concentric circles formed by each of the outlets 25d is formed in a nested manner. The cleaning gas supply nozzle 25 is disposed in the light emission direction of the condensing reflection mirror 4 so that it is blown directly toward each of the plurality of light reflection surfaces of the light reflection mirror 4.

(5) Further, in this state, the control unit 12 transmits a cleaning gas supply signal to the cleaning gas supply unit 24. The cleaning gas supply unit 24 that has received the cleaning gas supply signal supplies the cleaning gas into the delivery section 24 a of the cleaning gas supply nozzle 25. As a result, the cleaning gas is blown to each of the plurality of light reflecting surfaces of the condensing reflector 4 from the outlet 25d provided in the frame portion 25c, and the contaminant layer deposited on the light reflecting surface is efficiently removed. Is done.
It is preferable that the gas exhaust unit 8 is always driven while the third gate 23 is opened while the condensing reflector 4 is being cleaned with the cleaning gas. By doing so, the cleaning gas is sucked through the gas exhaust port 8a, so that the cleaning gas is improved from the end on the EUV light extraction side of the condensing reflector 4 toward the end on the plasma generation unit side. It is expected that it can be distributed and the post-treatment process can be carried out efficiently.

(6) The control unit 12 transmits a cleaning gas stop signal to the cleaning gas supply unit 24 after performing a post-processing step for a predetermined time. The cleaning gas supply unit 24 that has received the cleaning gas stop signal stops the supply of the cleaning gas. Further, the control unit 12 transmits a drive signal to the nozzle drive unit 24b. The nozzle driving means 24 b that has received the drive signal drives the cleaning gas supply nozzle 25 to retract the cleaning gas supply nozzle 25 from the optical path connecting the condenser reflector 4 and the extreme ultraviolet light outlet 5.
(7) In the second chamber 1b, the supplied cleaning gas is exhausted to the outside of the second chamber 1b by the gas exhaust unit 8 that is always in operation, so that no cleaning gas remains. In this state, the control unit 12 transmits a gate open signal to each of the first and second gate valves 21 and 22. The first and second gate valves 21 and 22 that have received the gate opening signal open the first and second gates 21 and 22, respectively, and the connecting portion 10a provided in the second chamber 1b and the EUV light. Each of the outlets 5 is opened. As a result, all of the first and second gates are opened. In this method, the third gate is kept open.

(8) In this state, the control unit 12 transmits a discharge gas supply signal to the discharge gas supply unit 6. The discharge gas supply unit 6 that has received the discharge gas supply signal supplies the discharge gas to the plasma generator 2. Moreover, the control part 12 transmits a gas supply signal with respect to the gas supply unit 7 for forming a gas curtain. The gas supply unit 7 that has received the gas supply signal supplies a gas curtain forming gas into the second chamber 1 b, and a gas curtain is formed between the plasma generator 2 and the foil trap 3.
(9) The controller 12 transmits a discharge start signal to the high voltage pulse generator 11 after the pressure of the discharge gas in the plasma generator 2 is optimized and the gas curtain is formed. The high voltage pulse generator 11 that has received the discharge start signal applies a high voltage pulse voltage to the first and second main discharge electrodes 2a and 2b, and discharge in the plasma generator 2 is resumed.

B. Second Method The second method is based on the premise that the plasma generator 2 has never discharged, and the cleaning gas constituent material is disposed on the light reflecting surface of the condensing reflecting mirror 4 in the second chamber 1b. The cleaning method is characterized in that both a pretreatment step for depositing and a posttreatment step for removing the contaminant layer deposited on the light reflecting surface of the condensing reflector 4 by the cleaning gas are performed.
The pretreatment process is performed as follows.
(1) The control unit 12 transmits a gate closing signal to each of the first, second, and third gate valves 21a, 22a, and 23a. The first, second, and third gate valves 21a, 22a, and 23a that have received the gate closing signal drive the first, second, and third gates 21, 22, and 23, respectively. 10a, EUV light extraction part 5, gas discharge port 8a is closed.
The controller 12 transmits a drive signal to the gas exhaust unit 8 to drive the gas exhaust unit 8.

(2) In this state, the control unit 12 transmits a drive signal to the nozzle drive unit 24b. The nozzle driving means 24b that has received the drive signal drives the cleaning gas supply nozzle 25 so that the cleaning gas blown out from each of the plurality of concentric circles formed by each of the outlets 25d is nested in the condenser reflector 4. The cleaning gas supply nozzle 25 is arranged in the light emitting direction of the condensing reflector 4 so that it can be sprayed directly toward each of the plurality of light reflecting surfaces formed in a shape.
(3) After the cleaning gas supply nozzle 25 is disposed at a predetermined position, the control unit 12 transmits a gas supply signal to the cleaning gas supply unit 24. The cleaning gas supply unit 24 that has received the gas supply signal supplies the cleaning gas into the delivery unit 24a. As a result, the cleaning gas is sprayed from the outlet provided in the frame portion 25c toward each of the plurality of light reflecting surfaces of the condensing reflecting mirror 4, and the cleaning gas constituent material adheres to each of the light reflecting surfaces. . The conditions for attaching the cleaning gas constituent material are as described in the first method.
At this time, since the gas is filled in the second chamber 1 b sealed by the first to third gates 21, 22, and 23, the cleaning gas constituent material is easily attached to the light reflecting surface. be able to.

(4) The control unit 12 transmits a cleaning gas stop signal to the cleaning gas supply unit 24 after depositing the cleaning gas constituent material on the light reflecting surface of the condenser reflector 4. The cleaning gas supply unit 24 that has received the cleaning gas stop signal stops the supply of the cleaning gas into the cleaning gas supply nozzle 25.
(5) Furthermore, the control unit 12 transmits a drive signal to the nozzle drive unit 24b. The nozzle driving means 24 b that has received the drive signal drives the cleaning gas supply nozzle 25 to retract the cleaning gas supply nozzle 25 from the optical path connecting the condenser reflector 4 and the extreme ultraviolet light outlet 5.
Then, the third gate 23 is opened by the third gate valve 23a, and the operating gas exhaust unit 8 exhausts the cleaning gas to the outside of the chamber 1b, so that no cleaning gas remains in the chamber 1b. Then, the control unit 12 transmits a gate open signal to each of the first and second gate valves 21 and 22. The first and second gate valves 21a and 22a that have received the gate opening signal open the first and second gates 21 and 22, respectively, and the connecting portion 10a of the second chamber 1b and the EUV light extraction outlet. Open each of 5. As a result, all of the first, second and third gates 21, 22, and 23 are opened.

(6) In this state, the control unit 12 transmits a discharge gas supply signal to the discharge gas supply unit 6. The discharge gas supply unit 6 that has received the discharge gas supply signal supplies the discharge gas to the plasma generator 2. Moreover, the control part 12 transmits a gas supply signal with respect to the gas supply unit 7 for forming a gas curtain. The gas supply unit 7 that has received the gas supply signal supplies a gas curtain forming gas into the second chamber 1 b, and a gas curtain is formed between the plasma generator 2 and the foil trap 3.
(7) The control unit 12 transmits a discharge start signal to the high voltage pulse generation unit 11 after the pressure of the discharge gas in the plasma generation unit 2 is optimized. The high voltage pulse generator 11 that has received the discharge start signal applies a high voltage pulse voltage to the first and second main discharge electrodes 2a and 2b, and discharge in the plasma generator 2 is started.
Then, when the plasma generation time elapses for a certain period of time, the thickness of the contaminant layer formed on the cleaning gas constituent material of the condensing reflector 4 is such that the reflectivity for extreme ultraviolet light on the light reflecting surface of the condensing reflector is When the value reaches a level below the allowable range, the post-processing step using the cleaning gas is performed by performing the procedure of (1) to (9) described in the first method, and deposited on the light reflecting surface. The contaminated layer is removed.

According to the extreme ultraviolet light source device of the present invention as described above, since the cleaning gas constituent material adheres to the light reflecting surface constituting material layer constituting the light reflecting surface of the condenser reflector, the extreme ultraviolet light emission Contamination that cannot be removed on the light reflection surface because the material constituting the source, the main discharge electrode, the material constituting the insulating material, the material constituting the foil trap, and the light reflection surface constituting material do not react. The possibility that the material layer is formed can be eliminated. Therefore, it is expected that the contaminant layer inevitably formed on the light reflecting surface of the condensing reflector can be completely removed as the plasma generation time elapses.
Furthermore, since the light reflecting surface is made of ruthenium (Ru), there is no possibility of reacting with the halogen gas, so that there is no possibility that the reflectance of the light reflecting surface with respect to extreme ultraviolet light will be lowered.

Furthermore, according to the extreme ultraviolet light source device of the present invention, since the first gate for partitioning the first chamber and the second chamber and the second gate for closing the EUV light extraction outlet are provided, the light is reflected by reflection. When cleaning the light reflecting surface of the mirror, the main discharge electrode and the cleaning gas react to deteriorate the main discharge electrode, or the cleaning gas flows out of the second chamber so that it is mounted on the exposure machine. There is no worry that the precision instrument will be corroded by the cleaning gas.
Further, according to the method for cleaning a condensing reflector according to the present invention, the cleaning gas constituent material can be reliably attached to the light reflecting surface constituent material of the condensing reflector, and as the plasma generation time elapses. It is possible to reliably remove the contaminant layer deposited on the condenser mirror.

Below, the experiment conducted in order to confirm the effect of this invention is demonstrated. Experimental samples according to examples and comparative examples were produced. In the following, Cl corresponds to a cleaning gas constituent material and Sn corresponds to a contaminant.
A. Example An example sample was prepared by placing a single QCM (Quartz Crystal Microbarance) sensor in a container kept in a chlorine (Cl) atmosphere, and performing a pretreatment step for depositing Cl on the surface of the sensor. Further, it was obtained by further performing a process of attaching Sn.
The QCM sensor has a very small amount of attachment based on the change in the electrical resonance frequency when a substance is attached to the surface of the crystal unit and the dimensions, elastic modulus, density, etc. of the crystal unit are changed equivalently. It is a sensor that quantitatively detects the kimono.
In the experiment, gold (Au) was vapor-deposited as an electrode on a quartz plate, and ruthenium (Ru) of the same degree as that provided on the actual condenser mirror was deposited thereon to collect and reflect the surface roughness. What was polished to the same extent as a mirror was used.

The details of the pretreatment process are as follows.
Flow rate of C1 gas supplied into the container: 500 sccm
Pressure due to Cl gas in the container: 2.0 × 10 ³ pa
Time for placing the QCM sensor in the container at the above pressure: 1 minute The thickness of the Cl layer and the thickness of the Sn layer formed on the surface of the QCM sensor in this case are as follows.
Cl layer thickness: 0.22 nm, 0.25 nm, 0.76 nm, 0.31 nm, 0.28 nm
Sn layer thickness: 1.29 nm, 1.07 nm, 0.9 nm, 0.98 nm, 1.11 nm

B. Comparative Example The comparative sample is a sample in which only Sn is adhered to each surface of the QCM sensor having the same specifications as the example sample, without depositing Cl. There are two types of comparative example samples, and the thickness of the Sn layer formed on each sample is different as follows.
Sn layer thickness of Comparative Sample 1: 0.72 nm
Sn layer thickness of Comparative Sample 2: 1.78 nm

C. Comparison of Example and Comparative Example Each of the example sample, the comparative example sample 1 and the comparative example sample 2 is placed in a container maintained in a Cl atmosphere, and a post-treatment process for removing the Sn layer is performed, and the QCM sensor The ratio of removal of the Sn layer formed on the surface of was measured. The detailed conditions of the post-treatment process are as shown below.
-Example The flow rate of Cl supplied into the sample container: 200 sccm
Pressure due to Cl gas in the container: 4.0 × 10 ² pa
・ Comparative sample 1
Flow rate of Cl supplied into the container: 200 sccm
Pressure due to Cl gas in the container: 4.0 × 10 ² pa
Comparative sample 2
Flow rate of Cl supplied into the container: 200 sccm
Pressure due to Cl gas in the container: 1.3 × 10 ⁴ pa
The experimental results are shown in Table 1.

As shown in Table 1, Comparative Examples Samples 1 and 2 that were not pretreated (Cl was not attached) had Sn layer removal rates of 58.9% and 41.6%, respectively. It was.
On the other hand, in the example samples 1 to 5 in which Cl was adhered to the surface by performing the pretreatment process, the removal rates of the Sn layer were 88.3%, 92.7%, 90.6%, and 97.4, respectively. The removal rate of the Sn layer was remarkably improved as compared with Comparative Samples 1 and 2.
Here, in Example Samples 1 to 5, the film thickness (nm) of the Cl layer deposited by the pretreatment process was 0.22, 0.25, 0.76, 0.31, and 0.28, respectively. . From these results, it is considered that the effect of the present invention can be obtained if at least the thickness of the Cl layer is 0.2 nm or more.
This is because the entire surface is covered with the Cl layer if the film thickness of the Cl layer is 0.2 nm or more, but the entire surface is not covered with the Cl layer when the film thickness of the Cl layer is small. Conceivable.
From this experimental result, even when the cleaning gas constituent material is adhered to the light reflecting surface constituent material of the condenser reflector instead of the QCM sensor, the contaminant layer deposited on the surface of the condenser reflector is surely It can be removed.
Therefore, in the extreme ultraviolet light source device equipped with the condensing reflector according to the present invention, the contaminant layer deposited on the light reflecting surface of the condensing reflector can be surely removed as the plasma generation time elapses. it is conceivable that.

  Further, extreme ultraviolet light having a wavelength of 13.5 nm is incident at an incident angle of 15 ° on the surface on which each of the example sample, the comparative example sample 1 and the comparative example sample 2 is formed, and before the post-processing step. The reflectance of extreme ultraviolet light after the post-treatment process was measured. The experimental results are shown in Table 2.

The present invention can be similarly applied to an extreme ultraviolet light source device other than the extreme ultraviolet light source having the configuration described in the above embodiment, and hereinafter, a DPP method employing a rotating electrode with reference to FIGS. 5 and 6. A case where the present invention is applied to an EUV light source apparatus will be described.
FIG. 5 shows a schematic configuration example of a DPP-type EUV light source apparatus employing a rotating electrode according to the second embodiment of the present invention.
The EUV light source device shown in FIG. 5 is basically the EUV light source device shown in FIG. 1 in which the first main discharge electrode and the second main discharge electrode are configured to be rotatable. This is almost the same as the EUV light source device shown in FIG. Therefore, the description of the components common to those in FIG.

In the example shown in FIG. 5, the chamber 1 is largely divided into a discharge space 31 that accommodates the discharge unit 20 and a condensing space 32 that accommodates the condensing reflector 4, and a partition wall is formed between the discharge space and the condensing space. 1c is provided, and a foil trap 3 is provided on the partition wall 1c.
The discharge space is connected to the first gas exhaust unit 81, and the condensing space is connected to the second gas exhaust unit 82. Each space is reduced in pressure by the gas exhaust units 81 and 82 connected thereto.
The pressure in the discharge space 31 and the pressure in the light collection space 32 connected to the optical system of the exposure apparatus (not shown) may need to cause a pressure difference depending on discharge conditions or other factors. With the exhaust configuration as described above, the two spaces can be differentially exhausted, and the pressure difference between the spaces can be set to a predetermined value.

The discharge unit 20 is arranged such that the first main discharge electrode 20a, which is a metal disk-shaped member, and the second main discharge electrode 20b, which is also a metal disk-shaped member, sandwich the insulating material 20c. Structure.
The center of the first main discharge electrode 20a and the center of the second main discharge electrode 20b are arranged substantially coaxially, and the first main discharge electrode 20a and the second main discharge electrode 20b have a thickness of the insulating material 20c. It is fixed at a position separated by the amount of. Here, the diameter of the second main discharge electrode 20b is larger than the diameter of the first main discharge electrode 20a.
A rotating shaft 20e of a motor 20d is attached to the second main discharge electrode 20b. Here, the rotation axis 20e is substantially the same as that of the second main discharge electrode 20b so that the center of the first main discharge electrode 20a and the center of the second main discharge electrode 20b are positioned substantially on the same axis as the rotation axis 20e. Mounted in the center.
The rotating shaft 20e is introduced into the chamber 1 through, for example, a mechanical seal 20f. The mechanical seal 20f allows rotation of the rotating shaft 20e while maintaining a reduced pressure atmosphere in the chamber 1.

A first slider 20g and a second slider 20h made of, for example, a carbon brush are provided below the second main discharge electrode 20b. The second slider 20h is electrically connected to the second main discharge electrode 20b. On the other hand, the first slider 20g is electrically connected to the first main discharge electrode 20a through a through hole penetrating the second main discharge electrode 20b. It should be noted that an insulation mechanism that is not shown in the figure prevents dielectric breakdown from occurring between the first slider 20g and the second main discharge electrode 20b that are electrically connected to the first main discharge electrode 20a. It is configured.
The first slider 20g and the second slider 20h are electrical contacts that maintain electrical connection while sliding, and are connected to the high voltage pulse generator 11. The high voltage pulse generator 11 supplies pulse power between the first main discharge electrode 20a and the second main discharge electrode 20b via the first slider 20g and the second slider 20h. To do.
That is, even if the motor 20d is operated and the first main discharge electrode 20a and the second main discharge electrode 20b are rotating, the first main discharge electrode 20a and the second main discharge electrode 20b are between the first main discharge electrode 20a and the second main discharge electrode 20b. Is supplied with pulsed power from the high voltage pulse generator 11 via the first slider 20g and the second slider 20h.

Wiring from the high voltage pulse generator 11 to the first slider 20g and the second slider 20h is made through an insulating current introduction terminal (not shown). The current introduction terminal is attached to the chamber 1 and makes electrical connection from the high voltage pulse generator 11 to the first slider 20g and the second slider 20h while maintaining a reduced-pressure atmosphere in the chamber 1. Make it possible.
The peripheral portions of the first main discharge electrode 20a and the second main discharge electrode 20b, which are metal disk-shaped members, are configured in an edge shape. When power is supplied from the high voltage pulse generator 11 to the first main discharge electrode 20a and the second main discharge electrode 20b, a discharge is generated between the edge-shaped portions of both electrodes. When discharge occurs, the peripheral portions of the first main discharge electrode 20a and the second main discharge electrode 20b become high temperature due to the discharge, so that the first and second main discharge electrodes 20a and 20b are made of, for example, tungsten or molybdenum. And made of a refractory metal such as tantalum. The insulating material 20c is made of, for example, silicon nitride, aluminum nitride, diamond, or the like.
A groove is provided in the periphery of the second main discharge electrode 20b, and solid Sn or solid Li, which is a raw material for high-temperature plasma, is supplied to the groove. In the raw material supply, solid Sn or solid Li may be disposed in the groove portion in advance, or may be supplied from the raw material supply unit 61. The raw material supply unit 61 is configured to supply, for example, solid Sn or Li to the groove portion of the second main discharge electrode 20b periodically.
Sn or Li disposed or supplied in the groove portion of the second main discharge electrode 20b moves to the EUV light condensing portion side that is the EUV light emission side of the discharge portion 20 by the rotation of the second main discharge electrode 20b.

On the other hand, the chamber 1 is provided with a laser irradiator 30 that irradiates the Sn or Li moved to the EUV collector side with laser light. The laser light from the laser irradiator 30 is condensed on the Sn or Li moved to the EUV condensing part side through a laser light transmitting window part (not shown) provided in the chamber 1 and laser light condensing means. Irradiated as light.
As described above, the diameter of the second main discharge electrode 20b is larger than the diameter of the first main discharge electrode 20a. Therefore, the laser beam can be easily aligned so that it passes through the side surface of the first main discharge electrode 20a and is irradiated to the groove portion of the second main discharge electrode 20b.

Sn or Li irradiated with laser light from the laser irradiator 30 is vaporized between the first main discharge electrode 20a and the second main discharge electrode 20b, and a part thereof is ionized. Under such a state, when pulse power having a voltage of about +20 kV to −20 kV is supplied from the high voltage pulse generator 11 between the first and second main discharge electrodes 20a and 20b, the first main discharge is generated. Discharge occurs between the edge-shaped portions provided in the periphery of the electrode 20a and the second main discharge electrode 20b.
Thereby, high temperature plasma is generated and EUV light having a wavelength of 13.5 nm is emitted from the high temperature plasma. The emitted extreme ultraviolet light is incident on the condensing reflecting mirror 4 provided in the condensing space 32 through the foil trap 3, is condensed, and is exposed from the EUV light extraction unit 5. The light is emitted to an irradiation unit that is a system.
As described above, the condensing reflector 4 is made of a dense metal such as ruthenium (Ru), molybdenum (Mo), and rhodium (Rh) on the reflecting surface side of the base material having a smooth surface made of nickel (Ni) or the like. As a result of coating, a plurality of light reflecting surfaces are formed in a nested manner so that extreme ultraviolet light having an oblique incident angle of 0 ° to 25 ° can be favorably reflected.

Here, also in the extreme ultraviolet light source device of the present embodiment, a process of generating discharge between the first and second main discharge electrodes 20a and 20b (plasma generation process) as in the first embodiment. As time elapses, a part of the material constituting the main discharge electrode in contact with the extreme ultraviolet light radiation source or the high-temperature plasma contained in the discharge gas is not captured by the foil trap 3 and the condensing reflector 4 A pollutant layer made of these pollutants is formed on the light reflecting surface.
Therefore, in the condensing reflector 4, the cleaning gas constituent material is adhered to the light reflecting surface constituting material layer constituting the light reflecting surface as shown in FIG. The condensing space 32 is provided with a cleaning gas supply unit 24 for supplying a cleaning gas and a cleaning gas supply nozzle 25. The cleaning gas supply nozzle 25 has the same configuration as that shown in FIG.
Then, the contaminant layer deposited on the light reflecting surface of the condensing reflecting mirror 4 due to the generation of plasma is removed by blowing a cleaning gas from the cleaning gas supply nozzle 25 to the light reflecting surface of the condensing reflecting mirror 4.

As described above, the cleaning gas supply nozzle 25 has a plurality of cleaning gases formed in a nested manner in the step of stopping the generation of plasma and cleaning the light reflecting surface of the condensing reflecting mirror 4. Arranged in the light exit direction of the condenser reflector 4 so as to be blown directly toward each of the light reflecting surfaces, and after the cleaning is finished, retreats from the optical path connecting the condenser reflector and the extreme ultraviolet light outlet. Thus, the inside of the chamber 1b can be moved by a predetermined nozzle driving means 24b.
Further, when cleaning the light reflecting surface of the condensing reflecting mirror 4, the first and second main discharge electrodes 20 a and 20 b are deteriorated by a cleaning gas such as a halogen gas, or connected to the condensing space 32. Therefore, it is necessary to prevent the precision instrument mounted in the exposed exposure machine from being eroded by the halogen gas. For this reason, the chamber 1 includes the first to third gates 21 to 23 and the first to third gate valves for sealing the inside of the second chamber 1b when the condenser reflector 4 is cleaned. 21a to 23a are provided.
The first to third gates 21 to 23 are provided between the discharge space 31 and the condensing space 32, the extreme ultraviolet light outlet 5, and three locations in the vicinity of the exhaust port leading to the gas exhaust unit 82, As will be described later, the first and third gate valves 21a to 23a are opened and closed before and after cleaning the light reflecting surface of the condenser reflector 4.

In the present embodiment, the cleaning for removing the contaminant layer deposited on the light reflecting surface of the condensing reflector is the same as in the first embodiment described above, the first method and the second method. Can be done.
In the first method, as described above, the cleaning gas constituent material is attached in advance to the light reflecting surface of the condensing reflecting mirror in the pretreatment step, and the light reflecting surface of the condensing reflecting mirror 4 is formed in the plasma generating step. When the contaminant layer is deposited, the post-treatment process is performed as described above to remove the contaminant layer deposited on the light reflecting surface of the condensing reflecting mirror 4.
That is, the generation of plasma is stopped, and the cleaning gas supply nozzle 25 is arranged in the light emitting direction of the condenser reflector 4. Then, the first to second gates 21 to 22 are closed, and cleaning is performed by blowing cleaning gas from the cleaning gas supply nozzle 25 toward each of the light reflecting surfaces of the condensing reflecting mirror 4.

Further, in the second method, as described above, after the condensing reflector is mounted on the extreme ultraviolet light source device, a cleaning gas constituent material is adhered to the light reflecting surface of the condensing reflector as a pretreatment step. When the contaminant layer is deposited on the light reflecting surface of the condensing reflector 4 in the plasma generation process, the post-treatment process is performed as described above, and the contaminant layer deposited on the light reflecting surface of the condensing reflector 4 is changed. Remove.
That is, in the pretreatment step in the second method, as described above, the first, second, and third gates 21, 22, and 23 are closed, the cleaning gas supply nozzle 25 is moved, and the cleaning gas is condensed into the reflecting mirror. 4 is arranged so as to be sprayed toward each of the plurality of light reflection surfaces formed in a nested manner, and a cleaning gas is supplied so that the cleaning gas constituent material is adhered onto the light reflection surface of the condensing reflection mirror 4. .
Then, when the pollutant layer is deposited on the light reflecting surface of the condensing reflector 4 in the plasma generation step, the post-treatment process is performed as described above, and the pollutant layer deposited on the light reflecting surface of the condensing reflector 4 is changed. Remove.

FIG. 6 shows a schematic configuration example of a DPP type EUV light source apparatus employing a rotating electrode according to a third embodiment of the present invention, and the configuration of the rotating electrode is different from that shown in FIG. Other configurations are almost the same as those of the EUV light source apparatus shown in FIG. Therefore, the description of the components common to those in FIG. In FIG. 6, the control unit 12, the exposure unit 13, and the like are omitted.
In FIG. 6, the first and second main discharge electrodes 20a and 20b, which are metal disk-shaped members, are arranged such that the edge portions of the peripheral edge where the electric field is concentrated when supplying pulse power are separated from each other by a predetermined distance. Placed in. That is, it is preferable to arrange each electrode so that a virtual plane including each electrode surface intersects.
The predetermined distance is the distance at the shortest distance between the edges of the peripheral portions of the electrodes 20a and 20b. By disposing in this way, a large amount of discharge is generated in the portion (discharge portion 45) where the distance between the edge portions of the peripheral portions of both electrodes is the shortest, so the discharge position is stabilized.

In the EUV light source device shown in FIG. 6, Sn, Li, etc., which are raw materials containing EUV radiation species, are liquefied by heating and stored in the containers 41, 42, and the liquefied raw materials are rotated about the rotation shaft 46. A part of the first and second main discharge electrodes 20a, 20b is configured to pass therethrough. By comprising in this way, the raw material containing EUV radiation seed | species is supplied to the edge part of each main discharge electrode 20a, 20b.
Specifically, as shown in FIG. 6, the first rotating electrode 20 a is immersed in a conductive first container 41 that houses a raw material 43 containing EUV radiation species that is partially liquefied. Are arranged as follows. Similarly, the second rotating electrode 20b is arranged so that a part thereof is immersed in the conductive second container 42 containing the liquefied raw material 43.
The first container 41 and the second container 42 are connected to the high voltage pulse generation unit 11 via an insulating power introduction unit 44 capable of maintaining a reduced pressure atmosphere in the first chamber 1a.
Since the liquefied Sn or Li as the raw material 43 is conductive, and the first and second containers 41 and 42 are also conductive, a high voltage pulse generator is provided between the first container 41 and the second container 42. By supplying the pulse power to 11, the pulse power is supplied between the first main discharge electrode 20a and the second main discharge electrode 20b partially immersed in the conductive raw material 43.
That is, the DPP type EUV light source device shown in FIG. 6 is configured such that the raw material supply unit (first and second containers) is positioned on the lower side and the EUV light extraction unit 5 is positioned on the upper side.

When the first and second main discharge electrodes 20a and 20b partially immersed in the conductive raw material 43 are rotated, the electrode portion to which the raw material is attached moves to the EUV light emission side. A laser irradiator 30 is provided on the EUV light emission side, and irradiates the raw material with laser light. The raw material is vaporized and ionized by this laser beam.
In this state, when pulse power is applied from the high voltage pulse generator 11 to the first and second main discharge electrodes, high temperature plasma is generated in the periphery between the electrodes, and EUV light is emitted from this plasma. Is done.
The emitted extreme ultraviolet light is incident on the condensing reflecting mirror 4 provided in the condensing space 32 through the foil trap 3 provided in the partition wall 1c, and is collected and collected from the EUV light extraction unit 5 as shown in the figure. The light is emitted to an irradiation unit which is an exposure machine side optical system which is omitted.
As described above, the condensing reflector 4 includes a plurality of light reflecting surfaces in which a metal such as ruthenium (Ru) is densely coated on the reflecting surface side of the base material having a smooth surface made of nickel (Ni) or the like. Is formed.

Also in the extreme ultraviolet light source device of this embodiment, as in the first and second embodiments, the debris is not captured by the foil trap 3 as the plasma generation process elapses. 4 is deposited on the light reflecting surface to form a contaminant layer. Therefore, in the condensing reflector 4, the cleaning gas constituent material is adhered to the light reflecting surface constituting material layer constituting the light reflecting surface as shown in FIG. The condensing space 32 is provided with a cleaning gas supply unit 24 for supplying a cleaning gas and a cleaning gas supply nozzle 25. The cleaning gas supply nozzle 25 has the same configuration as that shown in FIG.
Then, the contaminant layer deposited on the light reflecting surface of the condensing reflecting mirror 4 by the generation of plasma is blown directly from the cleaning gas supply nozzle 25 onto the light reflecting surface of the condensing reflecting mirror 4. Remove.

As described above, the cleaning gas supply nozzle 25 is arranged in the light emitting direction of the condensing reflector 4 in the cleaning step, and after the cleaning is finished, the condensing reflector and the extreme ultraviolet light outlet It is possible to move in the second chamber 1b by a predetermined nozzle driving means 24b so as to retreat from the optical path connecting the two.
The second chamber 1b includes first to third gates 21 to 23 and first to third gates for sealing the inside of the second chamber 1b when the condenser mirror 4 is cleaned. Gate valves 21a to 23a are provided.
In the present embodiment, the cleaning for removing the contaminant layer deposited on the light reflecting surface of the condensing reflector is performed in the same manner as in the first and second embodiments described above. Two methods can be used.
In the first method, as described above, the cleaning gas constituent material is attached in advance to the light reflecting surface of the condensing reflecting mirror in the pretreatment step, and the light reflecting surface of the condensing reflecting mirror 4 is formed in the plasma generating step. When the contaminant layer is deposited, the post-treatment process is performed as described above to remove the contaminant layer deposited on the light reflecting surface of the condensing reflecting mirror 4.
Further, in the second method, as described above, after the condensing reflector is mounted on the extreme ultraviolet light source device, a cleaning gas constituent material is adhered to the light reflecting surface of the condensing reflector as a pretreatment step. When the contaminant layer is deposited on the light reflecting surface of the condensing reflector 4 in the plasma generation process, the post-treatment process is performed as described above, and the contaminant layer deposited on the light reflecting surface of the condensing reflector 4 is changed. Remove.

It is sectional drawing which shows the outline of a structure of the extreme ultraviolet light source device of 1st Example of this invention. It is a figure which illustrates notionally the effect | action at the time of making a cleaning gas constituent material adhere before a contaminant layer is formed on the surface of a condensing reflector. It is a figure which expands and shows the cross section of the condensing reflective mirror which the cleaning gas component adhered. It is the schematic when a cleaning gas supply nozzle is seen from the direction which cleaning gas blows off. It is sectional drawing which shows the outline of a structure of the extreme ultraviolet light source device of 2nd Example of this invention. It is sectional drawing which shows the outline of a structure of the extreme ultraviolet light source device of the 3rd Example of this invention. It is a figure which shows the structure of the extreme ultraviolet light source device of a DPP system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chamber 1a 1st chamber 1b 2nd chamber 2 Plasma generation part 2a 1st main discharge electrode 2b 2nd main discharge electrode 2c Insulation material 3 Foil trap 4 Condensing reflecting mirror 5 EUV light extraction port 6 Discharge gas supply Unit 7 Gas supply unit 8 Gas exhaust unit 11 High voltage pulse generation unit 12 Control unit 13 Exposure unit 21 First gate 22 Second gate 23 Third gate 24 Cleaning gas supply unit 25 Cleaning gas supply nozzle 20 Discharge unit 20a First main discharge electrode 20b Second main discharge electrode 20c Insulating material 20d Motor 30 Laser irradiation machine

Claims (9)

A pre-processing method for a condensing reflector that collects extreme ultraviolet light emitted from an extreme ultraviolet light emitting species of a metal or metal compound at a predetermined position,
Condensation characterized by having a pretreatment step of attaching a cleaning gas constituent material to the light reflecting surface constituent material of the condenser mirror before the contaminant layer is formed on the surface of the condenser reflector. Reflector pre-processing method.   The pre-processing step according to claim 1 and the post-processing step after the pre-processing step, and after the contaminant layer is formed on the surface of the condenser reflector, the contaminant is removed by the cleaning gas. A method for cleaning a condensing reflecting mirror. The method for cleaning a condensing reflector according to claim 1, wherein the cleaning gas constituent material is chlorine (Cl).   The method for cleaning a condensing reflector according to claim 1, wherein the light reflecting surface constituent material is ruthenium (Ru). The method for cleaning a condensing reflector according to claim 1, wherein the contaminant layer is made of tin (Sn) or a tin (Sn) compound contained in the discharge gas. The method of cleaning a condensing reflector according to claim 2, wherein the pretreatment step and the posttreatment step are performed in the same container. A chamber having a light outlet;
A raw material supply means for supplying a raw material containing an extreme ultraviolet light emitting species of metal or metal compound to the chamber;
A plasma generator for generating high-temperature plasma by heating and exciting the extreme ultraviolet radiation species supplied into the chamber;
A condensing reflector that collects extreme ultraviolet light at a predetermined position;
In an extreme ultraviolet light source device comprising a cleaning gas supply means for supplying a cleaning gas for removing a contaminant layer deposited on the surface of the condenser reflector,
An extreme ultraviolet light source characterized in that a light reflecting surface for reflecting extreme ultraviolet light is formed on the condensing reflector, and a chlorine compound is generated on the light reflecting surface by a pretreatment with a cleaning gas. apparatus. The extreme ultraviolet light source device according to claim 7, wherein the chamber is provided with a shutter that divides the plasma generation unit and the chamber in which the condenser reflector is accommodated. A condensing reflecting mirror having a light reflecting surface for reflecting extreme ultraviolet light,
A condensing reflecting mirror characterized in that a cleaning gas constituent material adheres to a light reflecting surface constituent material.

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