JP2008098274A - Extreme ultra-violet ray source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extreme ultra-violet ray source device capable of evading the supply of discharge gas to a chamber in the case of an intermission, and appropriately adjusting pressure in a discharge gas introduction pipe, so as to excellently restart the discharge when the discharge is being stopped. <P>SOLUTION: The discharge gas containing an extreme ultra-violet ray radiation species is supplied to a plasma generating part 106 inside the chamber 100 via the discharge gas introduction pipe 11. EUV light generated in the plasma generating part 106 is collected by a condensing mirror 101 and emitted from a light take-out part 104. A second pressure monitor 6 detects the pressure inside the discharge gas introduction pipe 11. When the detected pressure exceeds the prescribed pressure, an exhaust valve 5 arranged in a discharge gas exhaust pipe 12 is opened, so that the discharge gas is exhausted from a second exhaust unit 8. When the pressure inside the discharge gas introduction pipe 11 is reduced, the exhaust valve 5 is closed, so that the discharge gas is prevented from being exhausted by the second exhaust unit 8. It is also adequate that purge gas is introduced to the discharge gas introduction pipe 11 in a plasma non-generating period. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an extreme ultraviolet light source device that emits extreme ultraviolet light. In particular, the present invention relates to an extreme ultraviolet light source device expected as an exposure light source for the next generation semiconductor integrated circuit.

As the semiconductor integrated circuit is miniaturized and highly integrated, an exposure machine for manufacturing the semiconductor integrated circuit is required to improve the resolution. 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 a high-density and 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-density and high-temperature plasma.

The LPP type extreme ultraviolet light source device emits laser light to a target made of raw materials including an extreme ultraviolet light source, generates high-density high-temperature plasma by laser ablation, and emits extreme ultraviolet light emitted therefrom. Is to be used.
On the other hand, a DPP type extreme ultraviolet light source device generates high-density and high-temperature plasma by discharge by applying a high voltage between electrodes supplied with a discharge gas including an extreme ultraviolet light source, and is emitted from there. It uses extreme ultraviolet light.
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 materials for generating the above-described high-density high-temperature plasma, but Li (lithium) ions, Sn ( Tin) ions are attracting attention.
For example, Sn is large because the extreme ultraviolet light conversion efficiency given by the ratio between the electric input necessary for generating high-density and high-temperature plasma and the radiation intensity of extreme ultraviolet light having a wavelength of 13.5 nm is several times larger than Xe. It is expected as a radiation source to obtain output 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.

(1) Structure of Conventional Extreme Ultraviolet Light Source Device FIG. 13 shows the configuration of a DPP extreme ultraviolet light source device.
As shown in FIG. 13, the DPP extreme ultraviolet light source device has a chamber 100 that is a discharge vessel. In the chamber 100, for example, a flange-shaped first main discharge electrode (cathode) 121 and a ring-shaped second main discharge electrode (anode) 122 are arranged with a ring-shaped insulating material 123 interposed therebetween. The first main discharge electrode 121 and the second main discharge electrode 122 are made of a refractory metal such as tungsten, molybdenum, or tantalum.
The insulating material 123 is made of, for example, silicon nitride, aluminum nitride, diamond, or the like. Here, the chamber 100 and the second main discharge electrode 122 are grounded.
The flange-shaped first main discharge electrode 121, the ring-shaped second main discharge electrode 122, and the ring-shaped insulating material 123 are arranged so that the respective through holes are positioned substantially on the same axis, thereby forming a communication hole. is doing. When pulse power is supplied between the first main discharge electrode 121 and the second main discharge electrode 122 to generate a discharge, high-density and 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 121 and the second main discharge electrode 122 is performed by a high voltage pulse generator 113 connected to the first main discharge electrode 121 and the second main discharge electrode 122. Made.

The first main discharge electrode 121, the second main discharge electrode 122, and the insulating material 123 constitute a DPP type plasma generation unit 106. The DPP type extreme ultraviolet light source device has various configuration examples other than the one shown in FIG. 1, but refer to Non-Patent Document 1 for that.
A tubular preionization insulating material 125 is provided on the convex portion of the flange-shaped first main discharge electrode 121. Further, a raw material introduction pipe 124 is connected to the preionization insulating material 125. A discharge gas introduction tube 111 provided in the discharge gas supply unit 110 is connected to the raw material introduction tube 124. Then, a discharge gas, which is a raw material containing extreme ultraviolet radiation species, is supplied from the discharge gas supply unit 110 to the inside of the plasma generation unit via the discharge gas introduction tube 111 and the raw material introduction tube 124.
On the second main discharge electrode 122 side of the chamber 100, a gas exhaust unit 112 for adjusting the pressure inside the plasma generation unit 106 and exhausting the inside of the chamber is connected to the gas exhaust port 105, and plasma generation is performed. A pressure monitor 126 for monitoring the pressure inside the unit 106 is connected. The gas exhaust unit 112 has gas exhaust means (not shown) such as a vacuum pump.

The chamber 100 is provided with a condenser mirror 101 that collects extreme ultraviolet light. The condensing mirror 101 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.
In addition, between the high-density and high-temperature plasma 107 and the condensing mirror 101, debris such as metal powder generated by sputtering a metal (for example, a discharge electrode) in contact with the high-density and high-temperature plasma 107 or the radioactive species A foil trap 102 is installed for capturing debris and the like caused by the above and reducing kinetic energy and passing EUV light.

Further, the control unit 115 provided in the DPP type extreme ultraviolet light source device shown in FIG. 13 is based on a light emission command signal from the control unit 116 of the exposure machine and the like, and the high voltage pulse generation unit 113 and the discharge gas supply unit 110. The gas exhaust unit 112 is controlled. For example, when the control unit 115 of the extreme ultraviolet light source device receives a light emission command signal from the control unit 116 of the exposure machine, the control unit 115 controls the discharge gas supply unit 110 to discharge into the plasma generation unit 106 in the chamber 100. Supply gas.
Further, based on the pressure data from the pressure monitor 126 provided in the chamber 100, the discharge gas supply amount from the discharge gas supply unit 110 is controlled so that the inside of the plasma generation unit 106 has a predetermined pressure, and the gas exhaust unit. The exhaust amount by 112 is controlled. Thereafter, in order to generate high-density and high-temperature plasma that emits extreme ultraviolet light, the high-voltage pulse generator is controlled to supply power between the first main discharge electrode and the second main discharge electrode.

(2) Radiation of extreme ultraviolet light In the extreme ultraviolet light source device of FIG. 13, radiation of extreme ultraviolet light is performed as follows.
A discharge gas is introduced into the chamber 100, which is a discharge vessel, from a discharge gas supply unit 110 through a raw material introduction tube 124 provided on the first main discharge electrode 121 side. The discharge gas is for efficiently forming a radiation source that emits extreme ultraviolet light having a wavelength of 13.5 nm in the high-density and high-temperature plasma generation unit of the plasma generation unit 106, and is, for example, stannane (SnH ₄ ). .
SnH ₄ introduced into the plasma generation unit 106 passes through a communication hole formed by the ring-shaped first main discharge electrode 121, second main discharge electrode 122, and insulating material 123, and is then supplied to the chamber 100. The gas flows to the side and reaches the gas discharge port 105. That is, the discharge gas that has reached the gas discharge port 105 is exhausted by the gas exhaust means provided in the gas exhaust unit 112.
Here, the pressure inside the plasma generation unit 106 is adjusted to 1 to 20 Pa.
This pressure adjustment is performed as follows, for example. First, the control unit 115 receives pressure data inside the plasma generation unit 106 output from the pressure monitor 126 provided in the chamber 100. The control unit 115 controls the discharge gas supply unit 110 and the gas exhaust unit 112 based on the received pressure data to adjust the supply amount and the exhaust amount of SnH ₄ into the chamber 100, so that the plasma generation unit 106. The pressure is adjusted to a predetermined pressure.

In a state where the discharge gas flows through the communication hole formed by the flange-shaped first main discharge electrode 121, the ring-shaped second main discharge electrode 122, and the ring-shaped insulating material 123, the second main A high voltage pulse voltage of approximately +20 kV to −20 kV is applied between the discharge electrode 122 and the first main discharge electrode 121 from the high voltage pulse generator 113.
As a result, creeping discharge is generated on the surface of the insulating material 123, so that the first main discharge electrode 121 and the second main discharge electrode 122 are substantially short-circuited. A large pulse current flows between the electrode 121 and the second main discharge electrode 122.
Thereafter, extreme ultraviolet light having a wavelength of 13.5 nm is emitted from the high-density and high-temperature plasma generated by the discharge gas generated inside the plasma generation unit 106 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 emitted extreme ultraviolet light is collected by the condensing mirror 101 provided on the second main discharge electrode 122 side, and is irradiated from the extreme ultraviolet light extraction unit 104 as an exposure machine side optical system (not shown). It is emitted to the part.

Here, the DPP type extreme ultraviolet light source device may be provided with a preionization means for preionizing the raw material containing the extreme ultraviolet light radiating species supplied into the chamber 100 when a discharge is generated in the chamber 100. . When generating extreme ultraviolet light, the pressure of the discharge part 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.
In FIG. 13, the preionization unit 127 includes a conductive convex portion of the first main discharge electrode 121, and a tubular preionization insulating material 125 inserted into the convex portion of the first main discharge electrode 121. The conductive material introduction tube 124 is inserted into the preionization insulating material 125.
The convex portion of the first main discharge electrode 121 and the raw material introduction tube 124 which are conductive are connected to the power source unit 114 for preliminary ionization. When a voltage pulse is applied from the preionization power supply unit 114 between the convex portion of the first main discharge electrode 121 and the raw material introduction tube 124, as shown in FIG. A creeping discharge is generated to promote ionization of the raw material containing the extreme ultraviolet radiation species introduced into the chamber 100. The preliminary ionization power supply unit 114 is controlled by the control unit 115.
Here, the convex portion of the first main discharge electrode 121, the preionization insulating material 125, and the raw material introduction tube 124 that are coaxially arranged also serve as a raw material supply path for supplying the raw material containing the extreme ultraviolet radiation species. ing. An example in which the preliminary ionization unit 127 is combined with the DPP type extreme ultraviolet light source device is disclosed in, for example, Patent Document 2.

(3) About discharge gas supply unit In FIG. 14, schematic structure of the discharge gas supply unit 110 is shown.
The discharge gas supply unit 110 includes a discharge gas filling vessel 1 filled with the liquefied discharge gas 2, the discharge gas filling vessel 1, and a discharge gas introduction tube 111 that connects the raw material introduction tube 124 shown in FIG. And a mass flow controller (MFC) 3 that is provided in the discharge gas introduction tube 111 and adjusts the supply amount of the discharge gas into the chamber 100. The discharge gas introduction tube 111 on the downstream side of the MFC 3 is provided with a shutoff valve 4 that closes the discharge gas introduction tube so that the discharge gas is not supplied into the chamber 100 during a plasma non-generation period described later.
The discharge gas filling container 1 placed in the cooling refrigerant is filled with liquefied SnH ₄ . A discharge gas generated by evaporation of the liquefied SnH ₄ in the discharge gas filled container 1 in the space in the discharge gas filled container 1 is supplied into the chamber 100 via the discharge gas introduction tube 111. The supply amount of the discharge gas into the chamber 100 is adjusted by adjusting the opening degree of the valve for introducing the discharge gas provided in the MFC 3.
JP 2004-279246 A JP 2003-218025 A “Current Status and Future Prospects of EUV (Extreme Ultraviolet) Light Source Research for Lithography” "Gas Safety Handbook for Semiconductor Industry" (published by Japan Society for Safety Engineering) (page 163)

However, according to such an extreme ultraviolet light source device, the following problems actually occurred.
Since the extreme ultraviolet light source device shown in FIG. 13 often employs a usage method in which EUV light irradiation is intermittently applied to a workpiece at regular time intervals, a pulse discharge duration in which pulse discharge is performed for a certain time is employed. The (period in which plasma is repeatedly generated) and the pulse discharge stop period (plasma non-generation period) are alternately repeated. When exchanging the workpiece, there is a relatively long pulse discharge stop period (plasma non-generation period).
A plurality of workpieces are held in a cassette. The above-mentioned work replacement is performed by loading a workpiece that has been irradiated with EUV light into a cassette that holds a plurality of workpieces that have been irradiated with EUV light, and then unloading a workpiece that has not been irradiated with EUV light. This is realized by carrying out the sheet to the EUV light irradiation area. Then, all the EUV light irradiated workpieces were loaded into a cassette holding a plurality of EUV light irradiated workpieces, and all EUV light unirradiated workpieces were unloaded from a cassette holding a plurality of EUV light unirradiated workpieces. When both cassettes are replaced. A relatively long pulse discharge stop period (plasma non-generation period) also exists when exchanging both cassettes.

However, the conventional extreme ultraviolet light source device continues to supply SnH ₄ gas to the plasma generation unit in the chamber not only during the pulse discharge duration but also during the pulse discharge stop period. In particular, the SnH ₄ gas is continuously supplied to the plasma generation unit in the chamber even in a relatively long pulse discharge stop period (plasma non-generation period) corresponding to the work exchange period and the cassette exchange period.
According to Non-Patent Document 2, SnH ₄ gas is unstable in a room temperature atmosphere and decomposes in a few days. On the other hand, when the temperature of the atmosphere is, for example, 100 ° C. or higher, it quickly decomposes. Immediately after the transition from the pulse discharge duration to the pulse discharge stop period is immediately after the stop of discharge between the first and second main discharge electrodes in the chamber, the first main discharge electrode and the second main discharge electrode The surface becomes a high temperature exceeding several hundred degrees Celsius.
When such continue supplying SnH ₄ gas to the plasma generating portion 106 of the chamber 100 in the context, the first main discharge electrodes 121, SnH ₄ gas collides with the surface of the second main discharge electrodes 122 are soon Disassembled into Then, Sn or Sn compound generated by the decomposition of SnH ₄ may adhere to the insulating material 123 in the plasma generation unit 106, the preionization insulating material 125 in the preionization unit unit 127, or the condenser mirror 101. found.

When Sn or an Sn compound adheres to the surface of the insulating material 123, the first main discharge electrode 121 and the second main discharge electrode 122 become conductive and short-circuited. As a result, the electric power supplied to the plasma generation unit 106 is supplied to the deposited Sn or Sn compound, and is not injected into the plasma, so that high-density and high-temperature plasma is less likely to be generated. descend.
In addition, the diameter of the ring-shaped plasma generation unit 107, which is a space surrounded by the first main discharge electrode 121, the second main discharge electrode 122, and the insulating material 123, is reduced, or the spatial shape of the plasma generation unit 107 is reduced. It becomes uneven. This makes the plasma discharge unstable.
Similarly, also on the inner surface of the preionization insulating material 125 in which creeping discharge occurs, immediately after the transition from the pulse discharge duration to the pulse discharge stop period, the temperature becomes higher than room temperature. Therefore, the SnH ₄ gas is quickly decomposed also in the preliminary ionization unit portion 127. As a result, Sn or an Sn compound adheres to the surface of the preionization insulating material 125 in the preionization unit portion 127, and the raw material introduction tube 124 and the first main discharge electrode 121 become conductive and short-circuited.

As a result, the electric power supplied to the preliminary ionization unit 127 is supplied to the adhered Sn or Sn compound, and does not contribute to the promotion of ionization of the raw material containing the extreme ultraviolet radiation species introduced into the chamber 100.
Due to these factors, the pulse-to-pulse energy stability of extreme ultraviolet light emitted from the plasma generation unit and the emission position stability of extreme ultraviolet light become unstable. That is, the characteristics of extreme ultraviolet light emitted from the extreme ultraviolet light source device become unstable.
Further, since Sn or Sn compound adheres to the surface of the condensing mirror 101, the reflectance of extreme ultraviolet light having a wavelength of 13.5 nm is reduced on the surface of the condensing mirror 101, so that the light is emitted from the light extraction portion 104 of the chamber. The intensity of emitted extreme ultraviolet light is reduced.

In order to deal with such a problem, the shutoff valve 4 is closed in a state in which the solenoid valve of the MFC 3 is closed or the solenoid valve of the MFC 3 is opened in order to avoid the supply of SnH ₄ gas into the chamber 100 when the discharge is stopped. Closing is not preferable in that it may cause the following problems.
When the electromagnetic valve of the MFC 3 is closed, a large amount of SnH ₄ gas stays in the discharge gas introduction tube 111. As described above, SnH ₄ gas decomposes in a few days in a room temperature atmosphere, so the decomposition of SnH ₄ gas does not progress so much in the pulse discharge stop period corresponding to workpiece replacement or cassette replacement. However, since the decomposition reaction has occurred, the influence of solid Sn produced by decomposition of SnH ₄ gas will be ignored if the accumulated pulse discharge stop period becomes longer after using the extreme ultraviolet light source device for a long time. Can not. That is, a large amount of solid Sn produced by decomposition of SnH ₄ gas adheres to the inner wall of the discharge gas introduction tube 111, thereby narrowing the flow path of SnH ₄ gas in the discharge gas introduction tube 111, There is a possibility that the supply of SnH ₄ gas to the surface becomes unstable.

Further, when the electromagnetic valve of the MFC 3 is closed, the pressure in the discharge gas introduction tube 111 is excessively increased, and the gas input side pressure of the MFC 3 is excessively increased. Therefore, when the MFC 3 is operated by opening the solenoid valve of the MFC 3 prior to the resumption of discharge, it takes time until the operation of the MFC 3 is stabilized. In some cases, the MFC itself may be defective.
Further, when the shutoff valve 4 is closed with the electromagnetic valve of the MFC 3 opened, as described above, a large amount of solid Sn produced by decomposition of the SnH ₄ gas adheres to the inner wall of the discharge gas introduction tube 111. The flow path of the SnH ₄ gas is narrowed in the discharge gas introduction pipe 111, and there is a possibility that the supply of SnH ₄ gas into the chamber 100 may become unstable, and the electromagnetic valve of the MFC 3 is opened prior to the restart of the discharge to open the MFC 3 When operating the MFC, it takes time until the operation of the MFC 3 is stabilized. In some cases, the MFC itself may be defective.

Even if the solenoid valve or shutoff valve 4 of the MFC 3 is closed in order to avoid such a problem, the pressure in the sealed discharge gas filling container 1 rises, so that when the discharge is restarted, It takes time until the pressure on the gas input side becomes excessively high and the operation of the MFC 3 is stabilized. In some cases, the MFC itself may be defective.
The occurrence of such a problem is not limited to the case where SnH ₄ is used as a radiation source of extreme ultraviolet light. For example, it is a problem that can be assumed even when Li or a Li compound is used as a radiation source for extreme ultraviolet light, which is expected as a radiation source for obtaining high output extreme ultraviolet light other than SnH ₄ .
The present invention has been made to solve the above-described problems of the prior art, and can prevent the discharge gas from being supplied into the chamber during the pause, and can properly resume the discharge when the discharge is stopped. An object of the present invention is to provide an extreme ultraviolet light source device capable of appropriately adjusting the pressure in the discharge gas introduction tube so as to be able to do so.

In the present invention, the above problem is solved as follows.
(1) Discharge gas supply means for supplying a discharge gas containing an extreme ultraviolet light radiation source of metal or metal compound to the chamber is discharged at the plasma generation unit by discharge generated between the main discharge electrodes arranged opposite to each other. In the extreme ultraviolet light source device that generates high density and high temperature plasma by heating and exciting gas, and emits extreme ultraviolet light from this high density and high temperature plasma,
The discharge gas supply means is provided in a discharge gas filling container filled with a discharge gas, a discharge gas introduction tube connecting the discharge gas filling container and the plasma generation unit, and a discharge gas introduction tube, and the plasma generation unit Discharge gas amount adjusting means for adjusting the amount of discharge gas introduced into the discharge gas, shut-off means for opening and closing the discharge gas introduction pipe, discharge gas exhaust pipe branched from the discharge gas introduction pipe upstream of the shut-off means, and discharge gas Exhaust means connected to the exhaust pipe, an exhaust valve provided in the discharge gas exhaust pipe for adjusting opening / closing of the discharge gas exhaust pipe, an exhaust valve control unit for controlling opening / closing of the exhaust valve, and upstream of the shut-off means and the exhaust valve And a pressure detection means provided in the discharge gas introduction pipe, and the exhaust valve controller adjusts the opening and closing of the exhaust valve in accordance with a detected pressure signal from the pressure detection means.
That is, a discharge gas exhaust pipe that branches from the discharge gas introduction pipe and is connected to an exhaust means for exhausting the discharge gas is provided. An exhaust valve is connected to the discharge gas exhaust pipe in order to adjust the pressure in the discharge gas introduction pipe. The exhaust valve controller controls the opening and closing of the exhaust valve according to the internal pressure of the discharge gas introduction pipe.
Then, when the discharge is stopped, the shutoff means for opening and closing the discharge gas introduction tube or the electromagnetic valve of the discharge gas amount adjustment means is closed so that the discharge gas is not supplied into the chamber, and the pressure in the discharge gas introduction tube is The pressure is adjusted so that the above-described problems do not occur when restarting the discharge.
In the above, the blocking means may not be provided, and the discharge gas amount adjusting means may also serve as the blocking means.
Further, in the above, when the discharge gas introduction pipe is closed by the shut-off means, the exhaust valve control unit adjusts the opening / closing of the exhaust valve according to the detected pressure signal from the pressure detecting means. May be.
(2) In the above (1), a gas supply means for supplying a gas that does not deposit metal or metal compound (hereinafter referred to as purge gas) or a gas that removes the metal or metal compound is provided, and the discharge gas is introduced into the plasma generator. When the operation is stopped, the gas is supplied to the discharge gas introduction tube.
(3) In the above (1) and (2), the gas supply means is connected to the discharge gas introduction pipe via a three-way valve, and either of the discharge gas or the gas of the above (2) is directed toward the chamber side by the three-way valve. Distribute one or the other.
(4) In the above (1), (2), and (3), the extreme ultraviolet light radiation source is any one of tin (Sn), lithium (Li), and stannane (SnH ₄ ).

In the present invention, the following effects can be obtained.
(1) In the pulse discharge stop period (plasma non-generation period), the electromagnetic valve of the shut-off means or discharge gas amount adjusting means is closed to avoid the supply of discharge gas into the chamber. There is no problem caused by the metal or metal compound adhering to the surface of the insulating material or reflecting mirror.
(2) By providing the discharge gas exhaust pipe and the exhaust valve connected to the exhaust means, the pressure in the discharge gas introduction pipe can be adjusted to a predetermined pressure during the pulse discharge stop period. As a result, it is avoided that the gas input side pressure of the discharge gas amount adjusting means becomes excessively high. When the discharge gas amount adjusting means is operated prior to restarting the discharge, the operation of the discharge gas amount adjusting means is stabilized until the operation is stabilized. Time can be shortened.
(3) The amount of gas staying in the discharge gas introduction tube is also small, and the amount of decomposition of the discharge gas such as SnH ₄ gas during the pulse discharge stop period corresponding to workpiece exchange or cassette exchange can be made smaller than before.
Therefore, even if the extreme ultraviolet light source device is used for a long time and the accumulated pulse discharge stop period becomes long, the influence of the solid metal or metal compound generated by the decomposition of the discharge gas can be reduced.
(4) In the non-plasma generation period, the purge gas is introduced into the discharge gas introduction tube, and the discharge gas staying in the discharge gas introduction tube is purged with the purge gas, whereby the influence of the amount of discharge gas staying in the discharge gas introduction tube is affected. It can be further reduced.
Further, by supplying a gas for removing the metal or metal compound to the discharge gas introduction tube, the influence of the discharge gas staying in the discharge gas introduction tube can be further reduced, and the discharge gas is generated by decomposition of the discharge gas. Even if solid metal or metal compound is deposited in the discharge gas introduction tube, it is possible to remove these deposits.
For this reason, even if the extreme ultraviolet light source device is used for a long time and the accumulated pulse discharge stop period becomes long, the influence of the metal or metal compound generated by the decomposition of the discharge gas such as SnH ₄ gas is further reduced. It becomes possible to do.

Hereinafter, embodiments of the present invention will be described.
(1) 1st Embodiment (when the interruption | blocking means is a solenoid valve of MFC)
FIG. 1 is a diagram showing a schematic configuration of an extreme ultraviolet light source device according to a first embodiment of the present invention. In this embodiment, the blocking means for opening and closing the discharge gas introduction tube described above is a discharge gas amount adjusting means ( The case where it is a solenoid valve of MFC) is shown.
In FIG. 1, 10 is a discharge gas supply unit of the present embodiment, 100 is the chamber described above, 113 is a high voltage pulse generator, and 115 is a control unit.
The configuration and operation of the chamber 100 are the same as those in FIG. 13, and the EUV light generated by the plasma generation unit 106 is collected by the condensing mirror 101 and is removed from the light extraction unit 104 by the side of the exposure apparatus not shown. The light is emitted to an irradiation unit that is an optical system.
The discharge gas supply unit 10 includes the discharge gas filling container 1 filled with the liquefied discharge gas 2 as described above, and discharge gas, which is a raw material containing the extreme ultraviolet radiation species, is discharged into the discharge gas introduction tube 11 (FIGS. 13 and 13). 14 to the plasma generation unit 106 in the chamber 100 through the discharge gas introduction tube 111).
For ease of understanding, the pressure monitor 126, the foil trap 102, the gas exhaust unit 112, the preionization power supply unit 114, the preionization insulating material 125, the raw material introduction pipe 124, etc. shown in FIG. 13 are omitted. Yes.

First, the discharge gas supply unit according to the present embodiment will be described below.
The discharge gas supply unit 10 is provided in the vicinity of the discharge gas filling container 1, the discharge gas introduction pipe 11 connecting the discharge gas filling container 1 and the chamber 100, and the chamber 100 of the discharge gas introduction pipe 11. A mass flow controller (MFC) 3 for adjusting the amount of discharge gas supplied to the discharge gas, a discharge gas exhaust pipe 12 branched from the discharge gas introduction pipe 11, a second exhaust unit 8 connected to the discharge gas exhaust pipe 12, An exhaust valve 5 for adjusting the opening and closing of the discharge gas exhaust pipe 12, an exhaust valve control section 7 for adjusting the opening of the exhaust valve, and a second pressure monitor 6 for detecting the pressure in the discharge gas introduction pipe 11. I have.
The discharge gas filling container 1 is immersed in a refrigerant such as fluorinate so that the liquefied discharge gas (SnH ₄ ) 2 filled in the internal space is in a liquid state.
In the internal space, the liquefied SnH ₄ is evaporated to generate a discharge gas.

The mass flow controller (MFC) 3 includes an electromagnetic valve 3 a that adjusts the supply amount of discharge gas into the chamber 100, an electromagnetic valve drive mechanism 3 b that operates the electromagnetic valve 3 a, and a discharge gas introduction tube 11 that connects the MFC 3 and the chamber 100. And an integrated flow rate comparison circuit unit 3c that detects the integrated flow rate of the discharge gas that has passed through and compares it with a reference integrated flow rate.
In the first embodiment, the electromagnetic valve 3a of the MFC 3 has a function as the shutoff valve 4 in FIG. 14, and a discharge gas introduction tube is provided so that the discharge gas is not supplied into the chamber 100 during the plasma non-generation period. 11 is closed.
The second exhaust unit 8 connected to the discharge gas exhaust pipe 12 is always in operation regardless of whether it is discharged or not. That is, at the time of discharge, the exhaust valve 5 is in a closed state so that the discharge gas is supplied into the chamber 100 without being guided to the discharge gas exhaust pipe 12. An example of the second exhaust unit 8 is a rotary pump.
The second pressure monitor 6 is provided in the discharge gas introduction pipe 11 upstream of the electromagnetic valve 3a and the exhaust valve 5 of the MFC 3 and always introduces discharge gas to the pressure comparison circuit section 7a of the exhaust valve control section 7. A detection pressure signal related to the pressure of the tube 11 is transmitted.

The exhaust valve control unit 7 includes a pressure comparison circuit unit 7a that receives the reference pressure signal transmitted from the control unit 115, an exhaust valve drive mechanism 7b that drives the exhaust valve 5 based on a command from the pressure comparison circuit unit 7a, It has.
When the detected pressure signal exceeds the reference pressure signal, the pressure comparison circuit unit 7a compares the detected pressure signal from the second pressure monitor 6 provided in the discharge gas introduction tube 11 with the reference pressure signal. The valve drive signal is transmitted to the exhaust valve drive mechanism 7b so as to open the exhaust valve 5.

In the present embodiment, in order to suppress the introduction of the discharge gas into the chamber 100 and to maintain the pressure in the discharge gas introduction tube 11 at a predetermined pressure during the rest, the second pressure monitor 6 The exhaust valve 5 is opened and closed according to the detected pressure signal.
Specifically, as will also be described with reference to FIGS. 2, 3 and 4 below, the pressure in the discharge gas introduction tube 11 is detected by the second pressure monitor 6 and the detected pressure becomes a predetermined pressure. When exceeding, the exhaust valve 5 provided in the discharge gas exhaust pipe 12 branched from the discharge gas introduction pipe 11 is opened, and the discharge gas is exhausted by the second exhaust unit 8.
On the other hand, when the detected pressure falls below a predetermined pressure, the exhaust gas is not exhausted in order to prevent the flow rate stability of the discharge gas from being impaired due to the pressure in the discharge gas introduction tube 11 being lowered. The valve 5 is closed so that the discharge gas is not exhausted by the second exhaust unit 8.
That is, the discharge valve 5 is controlled to be a predetermined pressure by opening and closing the exhaust valve 5 based on the pressure in the discharge gas inlet 11 detected by the second pressure monitor 6.

Next, an exhaust valve control method for the extreme ultraviolet light source device of the present embodiment will be mainly described with reference to the flowcharts shown in FIGS. 2 and 3 and the time chart shown in FIG.
Here, it is assumed that an exposure machine (not shown) having the extreme ultraviolet light source device as an exposure light source exposes a mask pattern onto a wafer coated with a resist or the like.
The exposure is performed by the following procedure, for example.
For the exposure of the wafer, a well-known step and repeat method or scan method is employed. When the exposure of one wafer is completed, the emission of extreme ultraviolet light from the extreme ultraviolet light source device stops. Thereafter, the exposed wafer is withdrawn from the exposure area. Then, a new unexposed wafer is transferred to the exposure area and is adjusted to a predetermined position in the exposure area. Based on this premise, the exhaust valve control method will be described.

The extreme ultraviolet light emission command (hereinafter also referred to as EUV light emission command signal) transmitted from the control unit of the exposure machine (not shown) to the control unit 115 of the extreme ultraviolet light source device is stopped (step S1, FIG. 2). O) in FIG.
Based on the received EUV light emission command, the control unit 115 of the extreme ultraviolet light source device (hereinafter also referred to as EUV light source device) that has transmitted the trigger signal to the high voltage pulse generation unit 113 transmits the trigger signal. Stop. As a result, the emission of extreme ultraviolet light (hereinafter also referred to as EUV light) stops (step S2 in FIG. 2 and p and q in FIG. 4).
The exposure machine starts the operation of retracting the exposed wafer, transporting the unexposed wafer to the exposure area, and adjusting the position of the unexposed wafer. At the start of this operation, the exposure apparatus transmits a wafer replacement start signal to the control unit 115 of the EUV light source device (step S3 in FIG. 2 and a in FIG. 4).
The control unit 115 of the EUV light source device transmits a reference pressure data signal to the pressure comparison circuit unit 7a of the exhaust valve control unit 7 based on the wafer replacement start signal. The reference pressure data signal is a signal indicating the upper limit value P _R1 and the lower limit value P _R2 of the allowable pressure range in the discharge gas introduction pipe (step S4 in FIG. 2, c in FIG. 4).

Further, the control unit 115 of the EUV light source device transmits a discharge gas supply stop signal for stopping the supply of the discharge gas to the electromagnetic valve drive mechanism 3b of the MFC 3 based on the wafer replacement start signal (step S5 in FIG. 2). FIG. 4 d).
The electromagnetic valve drive mechanism 3b of the MFC 3 that has received the discharge gas supply stop signal drives the electromagnetic valve 3a to be closed to close the discharge gas introduction tube 11 so that the discharge gas is not supplied into the chamber 100. To do. The flow rate of the discharge gas flowing through the MFC 3 gradually becomes 0 (step S6 in FIG. 2, f in FIG. 4).
When the electromagnetic valve 3a of the MFC 3 is closed, the exhaust valve 5 provided in the discharge gas exhaust pipe 12 remains closed, so that the pressure in the discharge gas introduction pipe 11 gradually increases as time passes (FIG. 4 g).

Here, the control unit 115 of the EUV light source apparatus verifies whether or not a wafer exchange end signal has been input from the control unit of the exposure apparatus. If the wafer exchange end signal has not been input, the process proceeds to step S8. On the other hand, if a wafer exchange end signal has been input, the process proceeds to step S14 (step S7 in FIG. 2).
In step S8, the pressure comparison circuit unit 7a compares the detected pressure signal transmitted from the second pressure monitor 6 with the reference pressure signal already input in step S4, and the pressure value in the discharge gas introduction tube 11 is compared. to test the magnitude of the P _P and the pressure upper limit value P _R1. The result of the test is transmitted from the pressure comparison circuit unit 7a to the control unit 115 of the EUV light source device. As a result of the test, if P _P > P _R1 , the process proceeds to step S9. On the other hand, if P _P ≦ P _R1 , the process proceeds to step S11.

When P _P > P _R1 , the gas input side pressure of the MFC 3 becomes excessively high. Therefore, when the MFC 3 is operated by opening the solenoid valve 3a of the MFC 3 prior to the resumption of discharge, it takes time until the operation of the MFC 3 is stabilized. In some cases, the MFC 3 itself may be defective.
Therefore, it is necessary to depressurize the discharge gas introduction tube 11 so that the pressure in the discharge gas introduction tube 11 falls below the pressure upper limit value P _R1 . Therefore, in step S9, the control unit 115 of the EUV light source device transmits a valve opening command signal to open the exhaust valve 5 to the exhaust valve driving mechanism 7b (h in FIG. 4).
The exhaust valve drive mechanism 7b that has received the valve opening command signal opens the exhaust valve 5 and exhausts the discharge gas in the discharge gas introduction tube 11 by the second exhaust unit 8 (steps S10 and FIG. 4 in FIG. 2). J).
When the exhaust valve 5 is opened and the discharge gas is exhausted, the pressure in the discharge gas introduction tube 11 gradually decreases with time. Since a predetermined time elapses from when the valve opening command signal is transmitted from the control unit 115 of the EUV light source device until the exhaust valve 5 is completely opened, the pressure in the discharge gas introduction tube 11 is set to open the valve. It descends gradually after a predetermined time from the command (g in FIG. 4). Then, it returns to step S7.

On the other hand, if the test result in step S8 is P _P ≦ P _R1 , the magnitude of the pressure value P _P and the pressure lower limit value P _R2 in the discharge gas introduction tube 11 is tested in step S11. When P _P ≦ P _R2 , the discharge gas pressure in the discharge gas introduction tube is low. Therefore, when the electromagnetic valve 3a of the MFC 3 is opened when exposure is resumed, the gas input side pressure of the MFC 3 becomes excessively high. Defects are suppressed.
Here, when the exhaust valve 5 is in an open state, the electromagnetic valve 3a of the MFC 3 is in a closed state, so that the pressure in the discharge gas introduction tube 11 gradually decreases. As the pressure P _P in the discharge gas introduction tube 11 decreases, the amount of discharge gas exhausted to the outside by the second exhaust unit 8 increases. That is, since the amount of discharge gas released outside without being used for EUV light emission increases, CoO (Cost of Operation) increases. Therefore, it is desirable to maintain the discharge gas pressure P _P in the discharge gas introduction tube at a predetermined lower limit value P _R2 or higher.

In step S11, when P _P ≧ P _R2 , the discharge gas pressure P _P in the discharge gas introduction tube 11 satisfies the condition P _R1 ≧ P _P ≧ P _R2 . And the amount of discharge gas exhausted by the second exhaust unit 8 is small. That is, it is not necessary to control the discharge gas pressure P _P in the discharge gas introducing tube 11, the flow returns to step S7.
On the other hand, when P _P <P _R2 , the amount of discharge gas exhausted to the outside exceeds a predetermined amount and CoO increases. Therefore, the pressure P _P in the discharge gas inlet pipe 11 is required to pressure increase the discharge gas introducing tube 11 to exceed the pressure lower limit value P _R2. That is, if P _P <P _R2 , the process proceeds to step S12.
In step S12, the control unit 115 of the EUV light source device transmits a valve close command signal to the exhaust valve drive mechanism 7b to close the exhaust valve 5 (i in FIG. 4).
The exhaust valve drive mechanism 7b that has received the valve close command signal closes the exhaust valve 5 and stops exhaust of the discharge gas in the discharge gas introduction tube 11 (step S13 in FIG. 2, j in FIG. 4).

When the exhaust valve 5 is closed and the discharge of the discharge gas is stopped, the pressure in the discharge gas introduction tube 11 gradually increases with time. Since a predetermined time elapses after the valve close command signal is transmitted from the control unit 115 of the EUV light source device until the exhaust valve 5 is completely closed, the pressure in the discharge gas introduction tube 11 is set to close the valve. It gradually rises with a predetermined time delay from the command (g in FIG. 4).
Then, it returns to step S7. As described above, in steps S8 and S9, the pressure P _P in the discharge gas introduction tube satisfies the condition P _R1 ≧ P _P ≧ P _R2 until it is determined in step S7 that the wafer replacement end signal has been input. , S10, S12, S13 are repeated as appropriate.

When the wafer transfer / position adjustment is completed in the exposure machine, a wafer exchange end signal is transmitted from the controller of the exposure machine to the control unit 115 of the EUV light source apparatus. In step S7, the wafer exchange end signal is input. The determination is made (Yes in step S7 in FIG. 2, b in FIG. 4).
The control unit 115 of the EUV light source apparatus that has received the wafer replacement end signal transmits a discharge gas supply start signal for starting supply of the discharge gas into the chamber 100 to the electromagnetic valve drive mechanism 3b of the MFC 3 (FIG. Step S14 of FIG. 2, e) of FIG.
The electromagnetic valve drive mechanism 3b of the MFC 3 that has received the discharge gas supply start signal drives the electromagnetic valve 3a to be in an open state to open the discharge gas introduction tube 11. The flow rate of the discharge gas into the chamber 100 reaches a peak after a few seconds have elapsed since the electromagnetic valve driving mechanism 3b opened the electromagnetic valve 3a (step S15 in FIG. 2, f in FIG. 4).

The control unit 115 of the EUV light source apparatus that has received the wafer replacement end signal transmits a valve closing command signal to close the exhaust valve 5 to the exhaust valve drive mechanism 7b (step S16 in FIG. 2, i in FIG. 4). ). The exhaust valve drive mechanism 7b that has received the valve close command signal closes the exhaust valve 5 so that the discharge gas is not exhausted (step S17 in FIG. 2, j in FIG. 4).
The pressure P _P in the discharge gas introduction tube 11 gradually increases with time as the exhaust valve 5 is closed. However, the electromagnetic valve 3a of the MFC 3 is also in an open state, and the discharge gas begins to flow into the chamber 100, so that an increase in pressure is suppressed. Then, when the operation of the MFC 3 is stabilized and the flow rate of the discharge gas flowing through the MFC 3 becomes constant, the pressure P _P in the discharge gas introduction tube becomes substantially constant (g in FIG. 4).

As described above, in the procedure from step S1 to step S17 described above, the discharge gas (for example, SnH ₄ ) is supplied into the chamber 100 during the pulse discharge stop period (plasma non-generation period) accompanying the wafer exchange operation or the like. Further, the pressure is controlled so that the pressure in the discharge gas introduction tube in the gas supply unit is maintained within a predetermined range.
Therefore, immediately after the transition from the pulse discharge duration to the pulse discharge stop period, SnH ₄ gas does not flow to the surfaces of the first main discharge electrode, the second main discharge electrode, and the preliminary ionization portion that are in a high temperature state. Therefore, Sn or Sn compound generated by the decomposition of SnH ₄ supplied into the chamber 100 during the pulse discharge stop period is an insulating material in the plasma generation unit 106, an insulating material for preionization in the preionization unit unit, or It is possible to effectively avoid adhesion to the condenser mirror 101.
Further, the amount of gas staying in the discharge gas introduction tube 11 is also small, and the amount of decomposition of SnH ₄ gas during the pulse discharge stop period corresponding to work exchange or cassette exchange can be made smaller than before. Therefore, even when the EUV light source device is used for a long period of time and the accumulated pulse discharge stop period becomes long, the influence of solid Sn generated by decomposition of SnH ₄ gas can be reduced.
Furthermore, it is avoided that the pressure on the gas input side of the MFC 3 becomes excessively high, and when the MFC 3 is operated by opening the solenoid valve 3a of the MFC 3 prior to restarting the discharge, the time is shortened until the operation of the MFC 3 is stabilized. be able to.

In the above control method, after the wafer replacement end signal is input to the EUV light source device (Yes in step S7), the electromagnetic valve 3a of the MFC 3 is opened (step S15), and the exhaust valve 5 is closed (step S17). ), Exposure can be started.
However, actually, as described above, the time when the operation of the MFC 3 is stabilized and the flow rate of the discharge gas flowing through the MFC 3 becomes constant is delayed by a predetermined time from the time when the steps S15 to S17 are completed. When pulse discharge is started in such a transient period in which the flow rate of the discharge gas flowing through the MFC is not stable, the output of EUV light is not stable. For this reason, the exposure processing of a workpiece such as a wafer varies, and in some cases, a problem may occur.
In order to avoid such a problem, it is desirable to start exposure when the flow rate of the discharge gas flowing through the MFC is stabilized.

Hereinafter, an example of a resumption procedure for determining whether or not the flow rate of the discharge gas flowing through the MFC is stable and starting exposure when the flow rate is stable will be described.
In the procedure 1 described below, it is determined whether or not the discharge gas flow rate is stable by using the measurement result of the integrated flow rate of the discharge gas that has passed through the discharge gas introduction tube 11, and in the procedure 2, the measurement result of the elapsed time is determined. Is used to determine whether or not the discharge gas flow rate is stable. Procedure 1 will be described with reference to steps S18 to S24 in FIG. 3 and FIG. 4, and procedure 2 will be described with reference to FIGS.
(A) Procedure 1
After the wafer exchange end signal is input to the EUV light source device, the integrated flow rate F of the discharge gas passing through the discharge gas introduction tube 11 connecting the MFC 3 and the chamber 100 is measured. The integrated flow rate from when the wafer replacement end signal is input to the control unit 115 of the EUV light source device until the discharge gas flow rate flowing through the MFC 3 is stabilized is stored in advance as the reference integrated flow rate F _S. When the measured integrated flow rate F _M exceeds the reference integrated flow rate F _S , it is determined that the discharge gas flow rate flowing through the MFC 3 is stable, and exposure is started.

The actual procedure will be described below with reference to steps S18 to S24 in FIG.
In the integrated flow rate comparing circuit 3c of MFC3, measuring the integrated flow rate F _M is assumed to be previously reset.
The control unit 115 of the EUV light source apparatus that has received the wafer exchange end signal transmits the discharge gas supply start signal (step S14 in FIG. 2) and the valve close command signal (step S16 in FIG. 2) and simultaneously integrates the MFC3. An integrated flow rate measurement start signal is transmitted to the flow rate comparison circuit unit 3c (step S18 in FIG. 3, k in FIG. 4). The integrated flow rate comparison circuit unit 3c of the MFC 3 starts measuring the integrated flow rate (m in FIG. 4).
In step S19, the integrated flow rate comparing circuit 3c compares the signal corresponding to the reference integrated flow F _S of signals corresponding to the measured integrated flow rate F _M that is input in advance, measuring the integrated flow rate F _M and the reference accumulated flow Test the magnitude with F _S. The result of the verification is transmitted from the integrated flow rate comparison circuit unit 3c to the control unit 115 of the EUV light source device.
If F _M <F _{S as} a result of the test, it is determined that the discharge gas flow rate flowing through the MFC 3 is not stable. Therefore, the test in step S19 is repeatedly executed (Yes in step S19 in FIG. 3).

On the other hand, when F _M ≧ F _S , it is determined that the discharge gas flow rate flowing through the MFC 3 is stable, and the process proceeds to step S20.
In step S20, the control unit 115 of the EUV light source apparatus transmits a standby signal to the control unit of the exposure machine (n in FIG. 4).
Further, the control unit 115 of the EUV light source device resets the integrated flow rate so that the integrated flow rate comparison circuit unit 3c of the MFC 3 resets the integrated flow rate of the discharge gas that has passed through the discharge gas introduction tube 11 connecting the MFC 3 and the chamber 100. A signal is transmitted (step S21 in FIG. 3, l in FIG. 4).

Accumulated flow rate comparing circuit 3c that receives the accumulated flow reset signal resets the value of the measured accumulated flow rate F _M to 0 (step S22 in FIG. 3, m in Fig. 4).
The controller of the exposure apparatus that has received the standby signal resumes transmission of the EUV light emission command signal to the controller 115 of the EUV light source device (step S23 in FIG. 3, o in FIG. 4).
The control unit 115 of the EUV light source apparatus that has received the EUV light emission command signal transmits a trigger signal to the high voltage pulse generation unit 113 and applies a high voltage pulse to the plasma generation unit 106 by the high voltage pulse generation unit 113. Cause a discharge. That is, exposure is resumed. (Step S24 in FIG. 3, p, q in FIG. 4).

(B) Procedure 2
In the procedure 1, the discharge flowing through the MFC 3 using the measurement result of the integrated flow rate of the discharge gas that has passed through the discharge gas introduction tube 11 connecting the MFC 3 and the chamber 100 from the time when the wafer replacement end signal is input to the EUV light source device. It was judged whether the gas flow rate was stable.
In Procedure 2, it is determined whether the discharge gas flow rate flowing through the MFC 3 is stable using the measurement result of the elapsed time instead of the integrated flow rate.
That is, timing is started after a wafer replacement end signal is input to the control unit 115 of the EUV light source device. The time from when the wafer replacement end signal is input to the EUV light source device until the discharge gas flow rate flowing through the MFC 3 is stabilized is stored in advance as the reference time T _S. When the time T _M exceeds the reference time T _S , it is determined that the flow rate of the discharge gas flowing through the MFC is stable, and exposure is started.

Hereinafter, an actual procedure will be described with reference to FIGS. The process corresponding to the procedure 2 is after step S18 ′ in the flowchart shown in FIG. 5, and the steps S1 to S17 are the same as those in FIG. 2 and are not shown in FIG.
The control unit 115 of the EUV light source apparatus has time measuring means (not shown). Hereinafter, as an example, an example in which a counter is used as a timing unit will be shown. It is assumed that the counter has been reset in advance.
The control unit 115 of the EUV light source apparatus that has received the wafer replacement end signal counts by the counter simultaneously with the transmission of the discharge gas supply start signal (step S14 in FIG. 2) and the valve closing command signal (step S16 in FIG. 2). To start. (Step S18 ′ in FIG. 5, r in FIG. 6).

In step S19 ', the control unit 115 of the EUV light source device compares the count number C _S corresponding to the reference time T _S, which is previously inputted and the count number C _M corresponding to the measured time T _M, the count number C The magnitude of _M and the count number C _S is tested.
As a result of the test, if C _M <C _S, it is determined that the discharge gas flow rate flowing through the MFC 3 is not stable. Therefore, the count in step S19 ′ is continued (Yes in step S19 ′ in FIG. 5).
On the other hand, when C _M = C _S , it is determined that the discharge gas flow rate flowing through the MFC is stable, and the process proceeds to step S20 ′. In step S20 ′, the control unit 115 of the EUV light source apparatus transmits a standby signal to the control unit of the exposure apparatus (n in FIG. 6). Further, the control unit 115 of the EUV light source device resets the count value of the counter to 0 (step S21 ′ in FIG. 5, r in FIG. 6).
Upon receiving the standby signal, the controller of the exposure apparatus resumes transmission of the EUV light emission command signal to the controller 115 of the EUV light source device (step S22 ′ in FIG. 5, o in FIG. 6).
The control unit 115 of the EUV light source apparatus that has received the EUV light emission command signal transmits a trigger signal to the high voltage pulse generation unit 113 and applies a high voltage pulse to the plasma generation unit 106 by the high voltage pulse generation unit 113. Cause a discharge. That is, exposure is resumed. (Step S23 ′ in FIG. 5, p, q in FIG. 6).

(2) Second embodiment (when a shut-off valve is used as the shut-off means)
FIG. 7 is a diagram showing a second embodiment according to the extreme ultraviolet light source apparatus of the present invention. The figure shows the vicinity of the MFC 3 and the control unit 115 in FIG. 1, and the other components are omitted, but are the same as those in FIG.
The EUV light source device shown in FIG. 7 is provided with a shutoff valve 4 in the discharge gas introduction pipe 11 downstream from the MFC 3 so that the discharge gas is not supplied into the chamber 100 during the non-plasma generation period. A feature is that a shut-off valve drive mechanism 4a for driving the shut-off valve 4 is provided.
According to the present embodiment, during the plasma non-generation period, the discharge gas introduction tube 11 is closed by closing the shutoff valve 4 by the shutoff valve drive mechanism 4a while the electromagnetic valve 3a of the MFC 3 is open. Thereby, the discharge gas is not introduced into the chamber 100 during the plasma non-generation period.

According to the first and second embodiments of the EUV light source apparatus of the present invention as described above, the electromagnetic valve 3a or the cutoff of the MFC 3 during the pulse discharge stop period (plasma non-generation period) accompanying the wafer exchange operation or the like. By closing the bulb 4, the discharge gas is not supplied into the chamber 100.
Therefore, immediately after the transition from the pulse discharge duration to the pulse discharge stop period, SnH ₄ gas or the like is applied to the surfaces of the first main discharge electrode 121 and the second main discharge electrode 122 that are in a high temperature state and the preliminary ionization unit 127. Discharge gas does not flow. Therefore, a metal such as Sn or a metal compound such as Sn compound generated by the decomposition of the discharge gas supplied into the chamber 100 during the pulse discharge stop period causes the insulating material 123, the preionization unit portion in the plasma generation unit 106 It is possible to effectively avoid adhesion to the pre-ionization insulating material 125 or the condenser mirror 101.
As a result, the power input to the plasma generation unit 106 and the power input to the preliminary ionization unit unit 127 are not supplied to the metal or metal compound attached to the plasma generation unit 106 or the preliminary ionization unit unit 127. Therefore, the electric power input to the preliminary ionization unit 127 surely contributes to the promotion of ionization of the raw material including the extreme ultraviolet light radiation species introduced into the chamber 100. Moreover, the electric power input to the plasma generation unit 106 is reliably supplied to the plasma. As described above, the conventional EUV light radiation intensity does not decrease.

In addition, the diameter of the ring-shaped plasma generation unit 106, which is a space surrounded by the first main discharge electrode 121, the second main discharge electrode 122, and the insulating material 123, is reduced, or the spatial shape of the plasma generation unit 106 is reduced. A stable plasma discharge can be realized without becoming non-uniform. That is, it is possible to maintain the pulse-to-pulse energy stability of extreme ultraviolet light emitted from the plasma generation unit 106 and the emission stability of extreme ultraviolet light (pointing stability).
Moreover, the pressure in the discharge gas introduction tube 11 can be adjusted as appropriate by opening and closing the exhaust valve 5 provided in the discharge gas exhaust tube 12. Therefore, it is avoided that the pressure on the gas input side of the MFC 3 becomes excessively high, and when the MFC 3 is operated by opening the solenoid valve of the MFC 3 prior to restarting the discharge, the time can be shortened until the operation of the MFC 3 is stabilized. it can. Further, the amount of gas staying in the discharge gas introduction tube 11 is also small, and the amount of decomposition of SnH ₄ gas during the pulse discharge stop period corresponding to work exchange or cassette exchange can be made smaller than before. Therefore, even when the EUV light source device is used for a long period of time and the accumulated pulse discharge stop period becomes long, the influence of solid Sn generated by decomposition of SnH ₄ gas can be reduced.
In particular, for example, the exposure is started after the operation of the MFC3 is stabilized and the flow rate of the discharge gas flowing through the MFC3 becomes constant, or after the output of the EUV light becomes stable, as in the above-described procedure 1 and procedure 2. By doing so, it is possible to effectively suppress variations in exposure processing in a workpiece such as a wafer.

(3) Third embodiment (using a three-way valve as means for introducing and shutting off purge gas)
As described above, in the first and second embodiments, the pressure in the discharge gas introduction tube can be adjusted as appropriate during the pulse discharge stop period (plasma non-generation period) associated with the wafer exchange operation. Therefore, the amount of discharge gas staying in the discharge gas introduction tube is also small, and the amount of decomposition of the discharge gas such as SnH ₄ gas during the pulse discharge stop period corresponding to workpiece exchange or cassette exchange can be made smaller than before. Therefore, even when the EUV light source device is used for a long period of time and the accumulated pulse discharge stop period becomes long, the influence of solid Sn generated by decomposition of SnH ₄ gas can be reduced.
In the third embodiment described below, a gas that does not deposit metal or a metal compound (referred to as a purge gas) or a gas that removes the metal or metal compound is introduced into the discharge gas introduction tube 11 in the plasma non-generation period. It is a thing.

By supplying the purge gas into the discharge gas introduction tube 11, the amount of the discharge gas staying in the discharge gas introduction tube becomes smaller than that in the first embodiment, and the discharge gas such as SnH ₄ gas is decomposed. The influence of the metal or metal compound produced can be further reduced.
Further, by supplying a gas for removing the metal or metal compound into the discharge gas introduction tube 11, the amount of the discharge gas staying in the discharge gas introduction tube 11 can be further reduced, and the discharge gas introduction Even if a metal or a metal compound generated by decomposition of a discharge gas such as SnH ₄ gas is deposited in the tube 11, these deposits can be removed.
For this reason, it is possible to further reduce the influence of the metal or metal compound generated by the decomposition of the discharge gas such as SnH ₄ gas.
As the purge gas, N ₂ (nitrogen) gas, rare gas [(He (helium), Ne (neon), Ar (argon)] so as not to deteriorate the constituent material (for example, stainless steel) of the discharge gas introduction tube. It is preferable to use an inert gas such as
As the gas for removing the metal or metal compound, hydrogen radical, halogen gas, halogen compound gas, or the like can be used.

FIG. 8 is a diagram showing a third embodiment according to the extreme ultraviolet light source apparatus of the present invention. In the following, the case where the purge gas is supplied into the discharge gas introduction tube during the non-plasma generation period will be described. However, the case where the gas for removing the metal or the metal compound is supplied can be similarly realized. 8, the same parts as those in FIGS. 1 and 13 are denoted by the same reference numerals, and the discharge gas supply container 1, the discharge gas introduction pipe 11, and the discharge gas supply amount into the chamber 100 are adjusted. The mass flow controller (MFC) 3, the discharge gas exhaust pipe 12 branched from the discharge gas introduction pipe 11, the second exhaust unit 8 connected to the discharge gas exhaust pipe 12, and the opening and closing of the discharge gas exhaust pipe 12 are adjusted And an exhaust valve controller 7 for adjusting the opening degree of the exhaust valve, and a second pressure monitor 6 for detecting the pressure in the discharge gas introduction pipe 11. In the internal space of the discharge gas filled container 1, the liquefied SnH ₄ is evaporated and a discharge gas is generated.

In addition to the above configuration, in this embodiment, a purge gas introduction pipe 13 is provided that branches from the discharge gas introduction pipe 11, and a purge gas supply unit 14 is connected to the purge gas introduction pipe 13. A three-way valve 9 is provided at a location where the discharge gas introduction tube 11 and the purge gas introduction tube 13 intersect. The three-way valve 9 is provided with a three-way valve drive mechanism 9 a that drives the three-way valve 9 based on a command from the control unit 115.
The three-way valve drive mechanism 9a is in response to a command from the control unit 115, and in the pulse discharge duration period, the downstream (chamber side) discharge gas introduction tube 11 side and the upstream (discharge gas filling container side) discharge gas introduction tube 11 side The three-way valve 9 is controlled such that the purge gas introduction pipe 13 side is closed (that is, the A direction open state and the B direction closed state in the gas flow direction).
Further, during the pulse discharge stop period, the upstream discharge gas introduction tube 11 side is closed and the downstream discharge gas introduction tube 11 side and the purge gas introduction tube 13 side are open (that is, in the gas flow direction, The three-way valve 9 is controlled so as to be in the A-direction closed state and the B-direction open state), and the purge gas is circulated in the discharge gas introduction pipe 11 on the downstream side of the three-way valve 9. In the present embodiment, the electromagnetic valve 3a of the MFC 3 is always open.
Here, the purge gas supply unit 14 is controlled by the control unit of the EUV light source device.

A control method for the third embodiment according to the extreme ultraviolet light source device of the present invention will be described below. 9 and 10 are flowcharts, and FIG. 11 is a time chart.
The EUV light emission command signal transmitted from the control unit of the exposure machine (not shown) to the control unit 115 of the EUV light source device stops (step S1 in FIG. 9 and o in FIG. 11).
Based on the received EUV light emission command, the control unit 115 of the EUV light source apparatus that has transmitted the trigger signal to the high voltage pulse generation unit 113 stops the transmission of the trigger signal. As a result, the emission of EUV light stops (step S2 in FIG. 9, p, q in FIG. 11).
The exposure machine starts the operation of retracting the exposed wafer, transporting the unexposed wafer to the exposure area, and adjusting the position of the unexposed wafer. At the start of this operation, the exposure apparatus transmits a wafer exchange start signal to the control unit 115 of the EUV light source device (step S3 in FIG. 9 and a in FIG. 11).
The control unit 115 of the EUV light source device transmits a reference pressure data signal to the pressure comparison circuit unit 7a based on the wafer exchange start signal. The reference pressure data signal is a signal indicating the upper limit value P _R1 and the lower limit value P _R2 of the allowable pressure range in the discharge gas introduction pipe (step S4 in FIG. 9, c in FIG. 11).

The control unit 115 of the EUV light source device transmits a discharge gas supply stop signal for stopping the supply of the discharge gas to the three-way valve drive mechanism 9a (step S5 ′ in FIG. 9, d in FIG. 11). The three-way valve drive mechanism 9a that has received the discharge gas supply stop signal closes the upstream discharge gas introduction pipe 11 side of the three-way valve 9 and also between the downstream discharge gas introduction pipe 11 side and the purge gas introduction pipe 13 side. The three-way valve 9 is controlled so as to be in an open state (that is, in the gas flow direction, the A direction closed state and the B direction open state) (step S6 ′ in FIG. 9, y in FIG. 11). As a result, the supply of the discharge gas into the chamber 100 is stopped (z1 in FIG. 11).
The control unit 115 of the EUV light source device controls the purge gas supply unit 14 and starts the purge gas supply operation. The purge gas flows in the direction B of the three-way valve 9, flows through the discharge gas introduction tube 11 and the MFC 3, and is introduced into the chamber 100 (step S65 in FIG. 9, z2 in FIG. 11). Note that the electromagnetic valve 3a of the MFC 3 is always open.
Here, in step S6 ′, the three-way valve 9 is closed on the upstream discharge gas introduction pipe 11 side, and the exhaust valve 5 provided in the discharge gas exhaust pipe 12 remains closed. The pressure in the discharge gas introduction tube 11 on the upstream side gradually increases with time (g in FIG. 11).
Here, the control unit 115 of the EUV light source apparatus verifies whether or not a wafer exchange end signal has been input from the control unit of the exposure apparatus (step S7 in FIG. 9). If the wafer exchange end signal has not been input, the process proceeds to step S8. On the other hand, if a wafer exchange end signal has been input, the process proceeds to step S14 (step S7 in FIG. 9).

In step S8, the pressure comparison circuit unit 7a compares the detected pressure signal transmitted from the second pressure monitor 6 with the reference pressure signal that has already been input in step S4. The magnitude of the pressure value P _P and the pressure upper limit value P _R1 is tested. The result of the test is transmitted from the pressure comparison circuit unit 7a to the control unit 115 of the EUV light source device. As a result of the test, if P _P > P _R1 , the process proceeds to step S9. On the other hand, if P _P ≦ P _R1 , the process proceeds to step S11.
When P _P > P _R1 , the pressure on the upstream discharge gas introduction tube 11 side of the three-way valve 9 becomes excessively high. Therefore, when resuming exposure, if the gas flow direction of the three-way valve 9 is the A direction, the gas input side pressure of the MFC 3 becomes excessively high. Therefore, when the MFC 3 is operated by opening the solenoid valve 3a of the MFC 3 prior to the resumption of discharge, it takes time until the operation of the MFC 3 is stabilized. In some cases, the MFC 3 itself may be defective.
Therefore, it is necessary to depressurize the discharge gas introduction tube 11 so that the pressure in the upstream discharge gas introduction tube 11 falls below the pressure upper limit value _PR1 .

Therefore, in step S9, the control unit 115 of the EUV light source device transmits a valve opening command signal to open the exhaust valve 5 to the exhaust valve driving mechanism 7b (h in FIG. 11).
Upon receiving the valve opening command signal, the exhaust valve drive mechanism 7b opens the exhaust valve 5 and exhausts the discharge gas in the upstream discharge gas introduction pipe 11 by the second exhaust unit 8 (step S10 in FIG. 9). J) in FIG.
When the exhaust valve 5 is opened and the discharge gas is exhausted, the pressure in the upstream discharge gas introduction pipe 11 gradually decreases with time. Since a predetermined time elapses from when the valve opening command signal is transmitted from the control unit 115 of the EUV light source device until the exhaust valve 5 is completely opened, the pressure in the discharge gas introduction tube 11 is set to open the valve. It descends gradually after a predetermined time from the command (g in FIG. 11). Then, it returns to step S7.

On the other hand, when P _P ≦ P _R1 , the magnitude of the pressure value P _P and the pressure lower limit value P _R2 in the discharge gas introduction tube 11 is tested in step S11. When P _P ≦ P _R2 , the discharge gas pressure in the upstream discharge gas introduction tube 11 is low. Therefore, when the gas flow direction of the three-way valve 9 is changed to the A direction upon resuming discharge, the gas input side pressure of the MFC 3 is Problems such as excessively high levels are suppressed.
Here, when the exhaust valve 5 is open, the pressure inside the discharge gas introduction tube 11 gradually decreases because the upstream discharge gas introduction tube 11 side of the three-way valve 9 is closed. As the pressure P _P in the discharge gas introduction pipe decreases, the amount of discharge gas exhausted to the outside by the second exhaust unit 8 increases. That is, since the amount of discharge gas released outside without being used for EUV light emission increases, CoO (CostofOperation) increases. Therefore, it is desirable to maintain the discharge gas pressure P _P in the discharge gas introduction tube 11 at a predetermined lower limit value P _R2 or more.

In step S11, when P _P ≧ P _R2 , the discharge gas pressure P _P in the discharge gas introduction tube 11 satisfies the condition P _R1 ≧ P _P ≧ P _R2 . When the gas flow direction is the A direction, the problem that the pressure on the gas input side of the MFC 3 becomes excessively high is suppressed, and the amount of discharge gas exhausted by the second exhaust unit 8 is small. That is, it is not necessary to control the discharge gas pressure P _P in the discharge gas introducing tube 11, the flow returns to step S7.
On the other hand, when P _P <P _R2 , the amount of discharge gas exhausted to the outside exceeds a predetermined amount and CoO increases. Therefore, it is necessary to depressurize the discharge gas introduction tube 11 so that the pressure P _P in the discharge gas introduction tube 11 exceeds the pressure lower limit value _PR2 . That is, if P _P <P _R2 , the process proceeds to step S12.
In step S12, the control unit 115 of the EUV light source device transmits a valve closing command signal to the exhaust valve driving mechanism 7b to close the exhaust valve 5 (i in FIG. 11).

The exhaust valve drive mechanism 7b that has received the valve close command signal closes the exhaust valve 5 and stops exhaust of the discharge gas in the discharge gas introduction tube 11 (step S13 in FIG. 9, j in FIG. 11). When the exhaust valve 5 is closed and the discharge of the discharge gas is stopped, the pressure in the discharge gas introduction tube 11 gradually increases with time. Since a predetermined time elapses after the valve close command signal is transmitted from the control unit 115 of the EUV light source device until the exhaust valve 5 is completely closed, the pressure in the discharge gas introduction tube 11 is set to close the valve. It gradually rises after a predetermined time delay from the command (g in FIG. 11). Then, it returns to step S7.
As described above, in steps S8 and S9, the pressure P _P in the discharge gas introduction tube satisfies the condition P _R1 ≧ P _P ≧ P _R2 until it is determined in step S7 that the wafer replacement end signal has been input. , S10, S12, S13 are repeated as appropriate.

When the wafer transfer / position adjustment is completed in the exposure machine, a wafer exchange end signal is transmitted from the controller of the exposure machine to the control unit 115 of the EUV light source apparatus. In step S7, the wafer exchange end signal is input. It is determined (Yes in step S7 in FIG. 9, b in FIG. 11).
The control unit 115 of the EUV light source apparatus that has received the wafer exchange end signal transmits a discharge gas supply start signal for starting supply of the discharge gas into the chamber 100 to the three-way valve drive mechanism 9a (FIG. 10). Step S14 ′, e) of FIG.
The three-way valve drive mechanism 9a that has received the discharge gas supply start signal opens the space between the upstream discharge gas introduction tube 11 side and the downstream discharge gas introduction tube 11 side of the three-way valve 9, and the purge gas introduction tube 13 side The three-way valve 9 is controlled so as to be in the closed state (that is, the A direction open state and the B direction closed state in the gas flow direction) (step S15 ′ in FIG. 10, y in FIG. 11). As a result, the supply of the purge gas into the chamber 100 is stopped (z2 in FIG. 11). Further, the supply of the discharge gas into the chamber 100 is started. The flow rate of the discharge gas into the chamber 100 reaches a peak after a few seconds have elapsed after the three-way valve 9 is controlled as described above (z1 in FIG. 11).

The control unit 115 of the EUV light source device controls the purge gas supply unit 14 and stops the purge gas supply operation (step S155 in FIG. 10).
Further, the control unit 115 of the EUV light source apparatus that has received the wafer exchange end signal transmits a valve close command signal to close the exhaust valve 5 to the exhaust valve drive mechanism 7b (step S16 in FIG. 10, i in FIG. 11). ). The exhaust valve drive mechanism 7b that has received the valve drive signal closes the exhaust valve 5 so that the discharge gas is not exhausted (step S17 in FIG. 10, j in FIG. 11).
The pressure P _P in the discharge gas introduction tube 11 gradually increases with time as the exhaust valve 5 is closed. However, the electromagnetic valve 3a of the MFC 3 is also in an open state, and the discharge gas begins to flow into the chamber 100, so that an increase in pressure is suppressed. Then, when the operation of the MFC 3 is stabilized and the flow rate of the discharge gas flowing through the MFC 3 becomes constant, the pressure P _P in the discharge gas introduction tube becomes substantially constant (g in FIG. 11).

In the above control method, after the wafer replacement end signal is input to the EUV light source device (Yes in step S7 in FIG. 9), the gas flow direction in the three-way valve 9 is the A direction open state and the B direction closed state. (Step S15 ′), exposure can be started when the exhaust valve 5 of the discharge gas supply unit 10 is closed (Step S17).
However, actually, as in the example shown in the first embodiment, the time when the operation of the MFC 3 is stabilized and the flow rate of the discharge gas flowing through the MFC 3 becomes constant is predetermined from the time when the steps S15 ′ and S17 are completed. Delay time. When pulse discharge is started in such a transient period in which the flow rate of the discharge gas flowing through the MFC 3 is not stable, the output of EUV light is not stable. For this reason, the exposure processing of a workpiece such as a wafer varies, and in some cases, a problem may occur.
In order to avoid such a problem, it is desirable to start the exposure when the flow rate of the discharge gas flowing through the MFC 3 is stabilized. As a procedure for determining whether or not the flow rate of the discharge gas flowing through the MFC 3 is stable and starting the exposure at the stable time, for example, any one of the procedures 1 and 2 shown in the first embodiment can be adopted. . The time chart shown in FIG. 11 shows an example in which the above procedure 1 is adopted, and the flowchart shown in FIG. 10 omits the restart procedure 1, but details of the procedure 1 are the same as those in the first embodiment. Since it is the same as the example shown, description will be omitted.
The reference integrated flow rate F _S is an integrated flow rate until the flow rate of the purge gas flowing through the MFC 3 becomes completely zero and the discharge gas flow rate flowing through the MFC 3 becomes stable.
When the procedure 2 is adopted, the reference time T _S is a time until the flow rate of the purge gas flowing through the MFC 3 becomes completely zero and the discharge gas flow rate flowing through the MFC 3 becomes stable.

(4) Fourth embodiment (purge gas introduction, use of a valve other than a three-way valve)
In the fourth embodiment described below, the discharge gas and the purge gas are switched using a valve other than the three-way valve in the third embodiment described above. That is, the discharge gas supply valve 15 provided in the discharge gas introduction tube 11 is used as the shut-off means, and the purge gas supply valve 16 is used as the purge gas supply means.
FIG. 12 shows a fourth embodiment according to the extreme ultraviolet light source apparatus of the present invention. This figure shows the vicinity of the discharge gas supply valve 15 and the purge gas supply valve 16 provided in place of the three-way valve 9 in FIG. 8 and the control unit 115, and the same parts as those shown in FIGS. Will not be described.
A purge gas introduction tube 13 is provided branched from the discharge gas introduction tube 11, and a purge gas supply unit 14 is connected to the purge gas introduction tube 13. A discharge gas supply valve 15 that opens and closes the discharge gas introduction tube 11 is provided upstream of the intersection of the discharge gas introduction tube 11 and the purge gas introduction tube 13, and a purge gas supply valve 16 is provided in the purge gas introduction tube 13. It is a feature.

The discharge gas supply valve 15 is provided with a discharge gas supply valve drive mechanism 15 a that drives the discharge gas supply valve 15 based on a command from the control unit 115. The purge gas supply valve 16 is provided with a purge gas supply valve drive mechanism 16 a that drives the purge gas supply valve 16 based on a command from the control unit 115.
During the pulse discharge duration, the discharge gas supply valve 15 is in the open state and the purge gas supply valve 16 is in the closed state (that is, in the gas flow direction, the A direction is open and the B direction is closed). The discharge gas supply valve 15 and the purge gas supply valve 16 are controlled.
During the pulse discharge stop period, the discharge gas supply valve 15 is closed and the purge gas supply valve 16 is open (that is, in the gas flow direction, the A direction is closed and the B direction is open). The discharge gas supply valve 15 and the purge gas supply valve 16 are controlled.
Note that the solenoid valve of the MFC 3 is normally open. The purge gas supply unit 14 is controlled by the control unit 115 of the EUV light source device.

According to the third and fourth embodiments of the EUV light source apparatus of the present invention as described above, as in the first and second embodiments, a pulse discharge stop period (plasma non-generation) accompanying a wafer exchange operation or the like is performed. In the period), the discharge gas is not supplied into the chamber 100. Therefore, immediately after the transition from the pulse discharge duration to the pulse discharge stop period, SnH ₄ gas or the like is applied to the surfaces of the first main discharge electrode 121 and the second main discharge electrode 122 that are in a high temperature state and the preliminary ionization unit 127. Discharge gas does not flow.
Therefore, a metal such as Sn or a metal compound such as Sn compound generated by the decomposition of the discharge gas supplied into the chamber 100 during the pulse discharge stop period causes the insulating material 123, the preionization unit portion in the plasma generation unit 106 It is possible to effectively avoid adhering to the preionization insulating material 125 or the condenser mirror 101 at 127.
As a result, as in the first embodiment, the pulse-to-pulse energy stability of extreme ultraviolet light emitted from the plasma generation unit 106 and the emission position stability of extreme ultraviolet light (pointing stability) are satisfactorily maintained. be able to.

Moreover, the pressure in the discharge gas introduction tube 11 can be adjusted as appropriate by opening and closing the exhaust valve 5 provided in the discharge gas exhaust tube 12. Therefore, when the gas flow direction of the three-way valve 9 becomes the A direction upon resuming the discharge, it is possible to suppress a problem that the gas input side pressure of the MFC 3 becomes excessively high.
Therefore, when the MFC 3 is operated by opening the electromagnetic valve of the MFC 3 prior to the resumption of discharge, the time can be shortened until the operation of the MFC 3 is stabilized.
In particular, in the third and fourth embodiments, the purge gas is introduced into the discharge gas introduction tube 11 during the non-plasma generation period, and the discharge gas staying in the discharge gas introduction tube is purged with the purge gas.
As a result, the amount of the discharge gas staying in the discharge gas introduction tube 11 becomes even smaller than that of the first embodiment, and the accumulated pulse discharge stop period becomes longer by using the EUV light source device for a long time. However, it is possible to further reduce the influence of the metal or metal compound generated by the decomposition of the discharge gas such as SnH ₄ gas.
Further, instead of the purge gas, in the non-plasma generation period, a gas for removing the metal or metal compound is supplied into the discharge gas introduction tube 11, or a gas for removing the metal or metal compound is mixed and supplied to the purge gas. You may do it.
In this way, even if solid metals or metal compounds generated by the decomposition of the discharge gas are deposited in the discharge gas introduction tube, these deposits can be removed.

In the first to fourth embodiments, the exhaust valve 5 is controlled to open and close according to the detected pressure signal from the second pressure monitor 6 during the pulse discharge stop period (plasma non-generation period). However, the opening and closing of the exhaust valve 5 may be controlled not only during the above period, but also while the discharge gas is supplied to the chamber 100 and pulse discharge is performed.
By performing such control, even if the amount of source gas supplied to the chamber 100 is smaller than the amount of source gas discharged from the discharge gas filling container 1, the pressure increase in the discharge gas introduction tube 11 is suppressed. Can do. Further, when the supply amount of the source gas to the chamber 100 is large, the pressure of the discharge gas introduction tube 11 is lowered and the exhaust valve 5 is closed, so that the operation is not hindered.
Moreover, in the said embodiment, although discharge gas is exhausted by the exhaust means 8, you may make it collect | recover and reuse the exhausted discharge gas.

It is a figure which shows the structure of the extreme ultraviolet light source device of the 1st Embodiment of this invention. It is a flowchart (1) which shows operation | movement of the 1st Embodiment of this invention. It is a flowchart (2) which shows operation | movement of the 1st Embodiment of this invention. It is a time chart which shows the operation | movement of the 1st Embodiment of this invention. It is a flowchart which shows the restart procedure 2 at the time of starting exposure. It is a time chart of the restart procedure 2 at the time of starting exposure. It is a figure which shows 2nd Embodiment which concerns on the extreme ultraviolet light source device of this invention. It is a figure which shows 3rd Embodiment which concerns on the extreme ultraviolet light source device of this invention. It is a flowchart (1) which shows operation | movement of the 3rd Embodiment of this invention. It is a flowchart (2) which shows operation | movement of the 3rd Embodiment of this invention. It is a time chart which shows the operation | movement of the 3rd Embodiment of this invention. It is a figure which shows 4th Embodiment which concerns on the extreme ultraviolet light source device of this invention. It is a figure which shows the structural example of the extreme ultraviolet light source device of a DPP system. It is a figure which shows schematic structure of the conventional discharge gas supply unit.

Explanation of symbols

1 Discharge gas filling container 2 Liquefied discharge gas 3 Mass flow controller (MFC)
3a Solenoid valve 3b Solenoid valve drive mechanism 3c Integrated flow rate comparison circuit section 4 Shut-off valve 4a Shut-off valve drive mechanism 5 Exhaust valve 6 Second pressure monitor 7 Exhaust valve control section 7a Pressure comparison circuit section 7b Exhaust valve drive mechanism 8 Second Exhaust unit 9 Three-way valve 9a Three-way valve drive mechanism 10 Discharge gas supply unit 11 Discharge gas introduction pipe 12 Discharge gas exhaust pipe 13 Purge gas introduction pipe 14 Purge gas supply unit 15 Discharge gas supply valve 16 Purge gas supply valve 100 Chamber 113 High voltage pulse generator DESCRIPTION OF SYMBOLS 115 Control part 106 Plasma production | generation part 101 Condensing mirror 104 Light extraction part 121 1st main discharge electrode 122 2nd main discharge electrode 123 Insulation material

Claims (6)

A chamber having a light outlet;
A discharge gas supply means for supplying a discharge gas including a metal or metal compound extreme ultraviolet radiation source to the chamber;
A plasma generator for generating high-density and high-temperature plasma by heating and exciting the discharge gas by the discharge generated between the main discharge electrodes arranged opposite to each other;
A condenser reflector for condensing extreme ultraviolet light emitted from the high-density high-temperature plasma at a predetermined position;
In an extreme ultraviolet light source device comprising a control unit,
The discharge gas supply means includes
A discharge gas filling container filled with the discharge gas;
A discharge gas introduction tube connecting the discharge gas filling container and the plasma generation unit;
A discharge gas amount adjusting means provided in a discharge gas introduction tube for adjusting the amount of discharge gas introduced into the plasma generation unit;
Blocking means for opening and closing the discharge gas introduction tube;
A discharge gas exhaust pipe branched from the discharge gas introduction pipe upstream of the blocking means;
Exhaust means connected to the discharge gas exhaust pipe;
An exhaust valve provided in the discharge gas exhaust pipe for adjusting the opening and closing of the discharge gas exhaust pipe;
An exhaust valve controller for controlling the opening and closing of the exhaust valve;
Pressure detecting means provided in the discharge gas introduction pipe upstream of the shutoff means and the exhaust valve,
The exhaust valve controller adjusts the opening and closing of the exhaust valve according to a detected pressure signal from the pressure detecting means. 2. The extreme ultraviolet light source device according to claim 1, wherein the discharge gas amount adjusting means also serves as the blocking means. 2. The exhaust valve controller adjusts opening and closing of the exhaust valve according to a detected pressure signal from the pressure detecting means when the discharge gas introduction pipe is closed by the shut-off means. Alternatively, the extreme ultraviolet light source device according to claim 2. In the extreme ultraviolet light source device, when the introduction of the discharge gas to the plasma generation unit is stopped, the gas that does not deposit the metal or the metal compound or the gas that removes the metal or the metal compound in the discharge gas introduction tube The extreme ultraviolet light source device according to claim 1, further comprising gas supply means for supplying the gas. The gas supply means is connected to a discharge gas introduction pipe through a three-way valve, and the three-way valve circulates either the discharge gas or the gas of claim 4 toward the chamber side. The extreme ultraviolet light source device according to claim 1, 2 or 3. The extreme ultraviolet light radiation source is any one of tin (Sn), lithium (Li), and stannane (SnH ₄ ). Ultraviolet light source device.

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