JP2011199001A - Extreme ultraviolet light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a supply amount of gas for a gas curtain that is formed in an EUV light extraction unit, and to minimize effects on an internal pressure of an EUV light-source unit and an exposure system.SOLUTION: EUV light emitted from a discharge unit 1 is converged by an EUV converging mirror 2 and is guided to the exposure system 31 in an exposure system housing 30 via an opening in the EUV light extraction unit 4. To prevent debris generated in the EUV light-source unit 10 from entering the exposure system 31, a gas-feed port 22 and an exhaust port 23 are arranged in the EUV light extraction unit 4 and the gas curtain is formed by flowing gas so that it may traverse the EUV light extraction unit 4. When light exposure is not performed, the EUV light-source unit stops operations (burst operations) for emitting light by pulse-like discharge and does not supply gas for forming the gas curtain or reduces the supply amount during this period. In this way, the amount of stop gas can be reduced.

Description

  The present invention relates to an extreme ultraviolet light source device, and more particularly to an extreme ultraviolet light source device in which a gas curtain is formed at an extreme ultraviolet light extraction portion in order to prevent debris generated in the light source device from entering an exposure machine. is there.

FIG. 5 shows a configuration example of a conventional extreme ultraviolet light source device (hereinafter, EUV light source device). This figure is a cross-sectional view in the direction along the optical axis.
The EUV light source apparatus 10 has a chamber 9 that is a discharge vessel. The chamber 9 collects EUV light emitted from a discharge unit 1 that is a heating excitation unit that heats and excites the EUV radiation species, and high-temperature plasma generated by heating and exciting the EUV radiation species by the discharge unit 1. A light-emitting EUV collector mirror 2 is provided. The EUV collector mirror 2 collects the EUV light and guides it from the EUV light extraction unit 4 provided in the chamber 9 to an irradiation optical system (not shown) of the exposure device 31 provided in the exposure device housing 30. . An exhaust unit 8 is connected to the chamber 9, and the inside of the chamber 9 is made a reduced pressure atmosphere by the exhaust unit 8.
The discharge unit 1 of the EUV light source device 10 is configured such that the first discharge electrode 11 that is a metal disk-shaped member and the second discharge electrode 12 that is also a metal disk-shaped member sandwich the insulating material 13. Arranged structure. The center of the first discharge electrode 11 and the center of the second discharge electrode 12 are arranged substantially coaxially, and the first discharge electrode 11 and the second discharge electrode 12 are separated by the thickness of the insulating material 13. It is fixed at the position. Here, the diameter of the second discharge electrode 12 is larger than the diameter of the first discharge electrode 11. Further, the thickness of the insulating material, that is, the separation distance between the first discharge electrode 11 and the second discharge electrode 12 is about 1 mm to 10 mm.

A rotation shaft 6 a of the motor 6 is attached to the second discharge electrode 12. The rotation shaft 6a is attached so that the center of the first discharge electrode 11 and the center of the second discharge electrode 12 are positioned substantially coaxially with the rotation axis. The rotating shaft 6a is introduced into the chamber 9 via, for example, a mechanical seal. The mechanical seal allows rotation of the rotating shaft 6a while maintaining a reduced pressure atmosphere in the chamber. Below the second discharge electrode 12, a first slider 12a and a second slider 12b made of, for example, a carbon brush are provided.
The second slider 12 b is electrically connected to the second discharge electrode 12. On the other hand, the first slider 12 a is electrically connected to the first discharge electrode 11 through a through hole 12 c that penetrates the second discharge electrode 12. In addition, it is comprised so that a dielectric breakdown may not generate | occur | produce between the 1st slider 12a and the 2nd discharge electrode 12. FIG. The first slider 12 a and the second slider 12 b are electrical contacts that maintain electrical connection while sliding, and are connected to the pulse power source 15. The pulse power power supply 15 has a frequency of, for example, 10 kHz between the rotating first discharge electrode 11 and the second discharge electrode 12 via the first slider 12a and the second slider 12b. Supply pulsed power.
Peripheral portions of the first discharge electrode 11 and the second discharge electrode 12 that are metal disk-shaped members are formed in an edge shape. As will be described later, when electric power is applied from the pulse power source 15 to the first discharge electrode 11 and the second discharge electrode 12, a discharge is generated between the edge-shaped portions of both electrodes. When discharge occurs, the vicinity of the electrodes becomes high temperature, so the first main discharge electrode 11 and the second main discharge electrode 12 are made of a refractory metal such as tungsten, molybdenum, or tantalum. The insulating material is made of, for example, silicon nitride, aluminum nitride, diamond, or the like.

The discharge unit 1 is supplied with tin (Sn) and lithium (Li), which are raw materials for high-temperature plasma. The raw material is supplied from the raw material supply unit 14 to the groove 12 d formed in the peripheral portion of the second discharge electrode 12. The motor 6 rotates only in one direction. When the motor 6 operates, the rotating shaft 6a rotates, and the second discharge electrode 12 and the first discharge electrode 11 attached to the rotating shaft 6a rotate in one direction. . Sn or Li supplied to the groove 12 d of the second discharge electrode 12 moves to the EUV light emission side in the discharge unit 1 by the rotation of the second discharge electrode 12.
On the other hand, the chamber 9 is provided with a laser irradiator 5 that irradiates the Sn or Li moved to the EUV light emission side with laser light. The laser irradiator 5 is composed of a YAG laser or a carbon dioxide gas laser. Laser light from the laser irradiator 5 passes through a laser light transmitting window portion (not shown) provided in the chamber 9 and laser light condensing means, and the groove portion 12d of the second discharge electrode 12 moved to the EUV emission side. Irradiation on Sn or Li. As described above, the diameter of the second discharge electrode 12 is larger than the diameter of the first discharge electrode 11. Accordingly, the laser light passes through the side surface of the first discharge electrode 11 and is irradiated to the groove portion of the second discharge electrode 12.

The emission of EUV light from the discharge unit 2 is performed as follows. From the laser irradiator 5, the laser light is irradiated to Sn or Li of the groove. Sn or Li irradiated with the laser light is vaporized between the first discharge electrode 11 and the second discharge electrode 12, and a part thereof is ionized. Under such a state, when a pulse power having a voltage of about +20 kV to −20 kV is applied between the first and second discharge electrodes 11 and 12 from the pulse power power supply 15, the first discharge electrode 11 and the second discharge electrode 11 and 12. Discharge occurs between the edge-shaped portions provided in the periphery of the two discharge electrodes 12.
At this time, a pulsed large current flows through a part of Sn or Li partially vaporized between the first discharge electrode 11 and the second discharge electrode 12. Thereafter, Joule heating by the pinch effect forms high-temperature plasma due to vaporized Sn or Li in the peripheral portion between both electrodes, and EUV light having a wavelength of 13.5 nm is emitted from this high-temperature plasma. As described above, since pulse power is applied between the first and second discharge electrodes 11 and 12, the discharge becomes a pulse discharge, and the emitted EUV light becomes pulsed light emitted in a pulse shape. Such light emission by pulsed discharge is called burst operation.

The EUV light emitted by the discharge unit 1 is collected by the oblique incidence type EUV collector mirror 2, and the exposure provided in the exposure machine casing 30 through the opening of the EUV light extraction unit 4 provided in the chamber 9. It is guided to the irradiation optical system of the machine 31 (not shown).
The EUV collector mirror 2 includes, for example, a plurality of spheroids having different diameters or mirrors having a rotating parabolic shape. These mirrors are arranged on the same axis so as to overlap the rotation center axis so that the focal positions substantially coincide with each other. For example, on the reflecting surface side of the base material having a smooth surface made of nickel (Ni) or the like, ruthenium ( By densely coating a metal film such as Ru), molybdenum (Mo), and rhodium (Rh), EUV light having an oblique incident angle of 0 ° to 25 ° can be favorably reflected.
A foil trap 3 is installed between the discharge unit 1 and the EUV light collecting mirror 2 in order to prevent damage to the EUV light collecting mirror 2. The foil trap 3 captures EUV by capturing debris such as metal powder generated by sputtering the first and second discharge electrodes 11 and 12 in contact with the high temperature plasma, debris caused by Sn or Li as a radioactive species, and the like. Allow only light to pass. The foil trap 3 includes a plurality of plates (foils) installed in the radial direction of the high temperature plasma generation region and a ring-shaped support that supports the plates so as not to block EUV light emitted from the high temperature plasma. It is configured.
If such a foil trap 11 is provided between the discharge part 1 and the EUV collector mirror 2, the pressure between the high temperature plasma and the foil trap 11 increases, and debris collision increases. Debris reduces kinetic energy by repeated collisions. Therefore, energy when debris collides with the EUV collector mirror 2 is reduced, and damage to the EUV collector mirror 2 can be reduced.

As described above, the EUV light emitted from the high-temperature plasma generated in the EUV light source device 10 is collected by the EUV collector mirror 2 and taken out from the EUV light extraction unit 4 of the chamber 9. The EUV light extraction unit 4 is connected to the EUV light incident unit 7 of the exposure machine 31 provided in the exposure machine housing 30. That is, the EUV light collected by the EUV collector mirror 2 enters the exposure unit 31 via the EUV light extraction unit 4 and the EUV incident unit 7.
The exposure machine 31 provided in the exposure machine housing 30 includes an illumination optical system (not shown) for using incident EUV light. The illumination optical system shapes the EUV light incident from the EUV light incident unit 7 and illuminates the mask on which the circuit pattern is formed. Since the optical system of the exposure machine 31 has no glass material that transmits EUV light, a reflection optical system including a mask is adopted, and the illumination optical system is also composed of one or more reflective optical elements such as a reflection mirror. . The light reflected by the reflective mask is reduced and projected onto a workpiece, for example, a wafer coated with a photoresist, by a projection optical system, and a reduced circuit pattern of the mask is formed on the workpiece. The projection optical system, like the illumination optical system, employs a reflective optical system and is composed of one or more reflective optical elements such as a reflective mirror.

Further, since EUV light is absorbed by air, all components such as the illumination optical system, mask, projection optical system, work, and work stage of the exposure machine 31 are placed in a vacuum. These components are installed in the exposure machine casing 30, and the interior of the casing 30 is exhausted by a gas exhaust unit (not shown) and maintained at a pressure lower than the pressure of the discharge container (chamber 9) of the EUV light source device 10. Is done. For example, the pressure in the discharge container of the EUV light source device 10 is about 1 Pa, and the pressure in the housing 30 of the exposure machine 31 is about 10 ⁻⁵ Pa.
As described above, the EUV light incident part 7 provided in the exposure machine casing 30 and the EUV light extraction part 4 provided in the EUV light source device 10 are connected. The inside of the chamber 9 and the inside of the exposure machine casing 30 of the EUV light source device 10 have a structure that enables differential exhaust by an exhaust unit provided in each.

By the way, various debris is generated in the EUV light source device. Examples of the debris include the following.
(1) Tin or lithium, which is a raw material for high-temperature plasma that scatters due to plasma expansion.
(2) High-speed (neutral) particles generated by plasma expansion are particles constituting the structure that are scattered by sputtering the structure in the light source device.
(3) Particles desorbed and suspended from the structure due to a photochemical reaction caused by irradiating the structure in the light source device with EUV light.
These debris generated in the EUV light source device 10 contaminates the illumination optical system when it enters the exposure unit 31 from the EUV light extraction unit 4. Therefore, the EUV light source device 10 must prevent debris from entering the exposure device 31 from the EUV light extraction unit 4. As one of the means, for example, as described in Patent Document 1, it is conceivable to provide a gas curtain.

As shown in FIG. 5, the gas curtain disclosed in Patent Document 1 is provided in a connection device 20 provided between the EUV light extraction unit 4 and the EUV light incident unit 7.
The connection device 20 has a communication hole 21, and the EUV light extraction unit 4 and the EUV light incident unit 7 face each other and are connected to open ends on both sides of the communication hole 21 of the connection device 20.
The communication hole 21 is provided with a gas introduction port 22 and an exhaust port 23 for exhausting the gas. The gas introduction port 22 is supplied with a stop gas that does not absorb extreme ultraviolet light from the gas supply unit 20a. The stop gas flows so as to intersect the EUV light passage direction and is forcibly exhausted from the gas exhaust port 23 by the exhaust unit 20b.
That is, a gas curtain is formed by the gas introduction port 22 and the exhaust port 23 to prevent inflow of a gas such as a cleaning gas from the EUV light source device to the exposure device 31.

FIG. 6 is a configuration example of a gas curtain including the gas supply unit 20 a and the exhaust unit 20 b provided in the connection device 20.
The gas inlet 22 is provided with a nozzle 22a for blowing out a stop gas from the nozzle 22a. As the stop gas, hydrogen that absorbs less EUV light or a rare gas (He, Ne, Ar, Kr, etc.) having no reactivity is used.
The gas exhaust port 23 is provided with a diffuser 23a, and the diffuser 23a is provided to face the nozzle 22a on the gas supply unit 20a side. The stop gas blown out from the nozzle 22a is sucked into the diffuser 23a of the gas exhaust unit 20b and exhausted.

JP 2009-212268 A

As shown in FIG. 5, a connecting device 20 is provided between the EUV light extraction unit 4 and the EUV light incident unit 7, and a stop gas introduction port 22 and an exhaust port 23 are opposed to the communication hole 21. The gas in the chamber 9 (first decompression container) is exposed to the exposure machine casing 30 (second chamber) by flowing a stop gas so as to intersect the direction of passage of extreme ultraviolet light and forming a gas curtain. The pressure can be reduced as much as possible.
However, in the case shown in FIG. 5, a connecting device 20 is provided between the EUV light extraction part 4 and the EUV light incident part 7, and a diffuser 23a and a nozzle 22a are provided in the middle of the communication hole 21 so as to face the gas curtain. The structure of the apparatus is relatively complicated.
Further, in order to prevent debris generated in the EUV light source device 10 from entering the exposure device 31 from the EUV light extraction unit 7, the stop gas needs a flow rate of about 20 liters / minute in calculation. When such a large amount of gas is supplied, it may be difficult to maintain the inside of the EUV light source device 10 at a desired pressure (about 1 Pa) even if exhaust is performed using exhaust means disposed opposite to each other. is there.
In addition, the inside of the exposure machine casing 30 must be kept at a high vacuum, for example, a pressure of about 10 ⁻⁵ Pa in order to prevent the EUV light from being attenuated. However, if the amount of the stop gas is large, it can be considered that it flows from the opening (communication hole 21) of the EUV light incident portion 7 to the exposure machine housing 30 side, and the pressure of the exposure machine 31 may be affected.
The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to reduce the amount of gas supplied to a gas curtain formed in an EUV light extraction portion that connects an EUV light source device and an exposure machine. It is possible to reduce the influence on the pressure in the EUV light source device and the exposure machine as much as possible.

An EUV light source when the exposure machine is not performing exposure, that is, while the wafer is moving from one exposure area to the next exposure area or when the exposed wafer is replaced with the next exposure wafer. The apparatus stops the burst operation (the operation of emitting light by pulsed discharge) and does not emit EUV light.
Therefore, in the present invention, while the generation of the EUV light is stopped, the stop gas for forming the gas curtain is not supplied in the EUV light extraction unit or the supply amount of the stop gas is reduced. Thereby, the amount of stop gas can be reduced.
As described above, the present invention solves the above problems as follows.
(1) A first decompression vessel provided with an extreme ultraviolet light generating unit that generates extreme ultraviolet light by a burst operation, and an interior from the first decompression vessel into which extreme ultraviolet light emitted from the first vessel is incident A second decompression container having a low pressure, and the first decompression container and the second decompression container are connected via a partition wall having an opening through which extreme ultraviolet light passes, and the extreme ultraviolet light in the opening is In an extreme ultraviolet light source device provided with a gas supply means for supplying a gas for forming a gas curtain and a gas exhaust means for exhausting the supplied gas on the incident side, the gas from the gas supply means The supply is synchronized with the burst operation in the extreme ultraviolet light generation unit, and the gas supply amount is controlled to increase during the burst operation, and the gas supply amount is reduced or zero when the burst operation is not performed. .
(2) In the above (1), the supply of gas from the gas supply means is stopped while the generation of extreme ultraviolet light is stopped between burst operations.

In the present invention, the following effects can be obtained.
(1) Since the gas supply amount is controlled to increase during the burst operation, and the gas supply is stopped or reduced when the burst operation is not being performed, the amount of the stop gas for forming the gas curtain is reduced. Can be reduced. For this reason, it becomes possible to maintain the inside of the EUV light source device at a desired pressure (about 1 Pa).
(2) Since the amount of the stop gas flowing into the exposure machine can be reduced, the influence on the pressure of the exposure machine is reduced.

It is a figure which shows the structure of the EUV light source device of the Example of this invention. It is a figure which shows the structural example of the gas supply means and gas exhaust means for forming a gas curtain. It is a time chart which shows the operation timing of operation | movement of a gas curtain and burst operation | movement. It is a time chart which shows the other operation example of a gas curtain and burst operation | movement. It is a figure which shows the structural example of the conventional extreme ultraviolet light source device. It is a figure which shows the structural example of the gas supply means and gas exhaust means for forming the gas curtain in the conventional extreme ultraviolet light source device.

FIG. 1 shows the configuration of an EUV light source apparatus according to an embodiment of the present invention. This figure is a cross-sectional view in the direction along the optical axis. Compared to the conventional EUV light source device shown in FIG. 5, the chamber 9 (first decompression container) and the exposure machine casing 30 (second decompression container). ) Are different from each other in configuration, and the operation of the gas supply unit 20a configuring the gas curtain is controlled by the control unit 40, and the other configurations are the same.
As described above, the EUV light source device has the chamber 9 which is a discharge container, and in the chamber 9, the discharge unit 1 which is a heating excitation means for heating and exciting the EUV radiation species, the foil trap 3, and An EUV collector mirror 2 that collects EUV light is provided. The EUV collector mirror 2 collects the EUV light and guides it from an EUV light extraction unit 4 provided in the chamber 9 to an irradiation optical system (not shown) of the exposure machine 31 provided in the exposure machine housing 30. . An exhaust unit 8 is connected to the chamber 9, and the inside of the chamber 9 is made a reduced pressure atmosphere by the exhaust unit 8.
As described above, the discharge unit 1 is provided with the first discharge electrode 11 and the second discharge electrode 12 that are rotated by the motor 6, and the pulse power power supply 15 supplies the first slider 12 a and the second slider. For example, pulse power having a frequency of 10 kHz is supplied between the first and second discharge electrodes 11 and 12 via the moving element 12b. When power is applied to the first discharge electrode 11 and the second discharge electrode 12, a discharge is generated between the edge-shaped portions of both electrodes.

A raw material such as Sn or Li is supplied from a raw material supply unit 14 to a groove 12d formed in the peripheral portion of the second discharge electrode 12, while the chamber 9 is a laser that irradiates the raw material with laser light. An irradiator 5 is provided.
When laser light is irradiated to Sn or Li of the groove 12d from the laser irradiator 5, it is vaporized between the first discharge electrode 11 and the second discharge electrode 12, and a part thereof is ionized. Under such a state, when a pulse power having a voltage of about +20 kV to −20 kV is applied between the first and second discharge electrodes 11 and 12 from the pulse power power supply 15, the first discharge electrode 11 and the second discharge electrode 11 and 12. Discharge occurs between the edge-shaped portions provided in the periphery of the two discharge electrodes 12.
At this time, a pulsed large current flows through a part of Sn or Li partially vaporized between the first discharge electrode 11 and the second discharge electrode 12. Thereafter, Joule heating by the pinch effect forms high-temperature plasma due to vaporized Sn or Li in the peripheral portion between both electrodes, and EUV light having a wavelength of 13.5 nm is emitted from this high-temperature plasma. This discharge becomes a pulse discharge, and the emitted EUV light becomes pulsed light emitted in a pulse form.

The EUV light emitted by the discharge unit 1 is collected by the oblique incidence type EUV collector mirror 2 and provided in the exposure machine casing 30 through the communication hole 21 of the EUV light extraction unit 4 provided in the chamber 9. Then, the exposure apparatus 31 is guided to an irradiation optical system (not shown).
As described above, the EUV light emitted from the high-temperature plasma generated in the EUV light source device 10 is collected by the EUV collector mirror 2 and taken out from the EUV light extraction unit 4 of the chamber 9. The EUV light extraction unit 4 is connected to the EUV light incident unit 7 provided in the exposure machine casing 30 through a communication hole 21. That is, the EUV light collected by the EUV collector mirror 2 enters the exposure machine casing 30 via the EUV light extraction unit 4 and the EUV incident unit 7.
Further, in order to prevent debris generated in the EUV light source device 10 from entering the exposure machine housing 30, the EUV light extraction unit 4 is provided with a gas curtain.

The gas curtain is provided with a gas introduction port 22 and an exhaust port 23 on the light incident side of the EUV light extraction unit 4 so as to face each other, and gas is introduced from the introduction port 22 so as to cross the EUV light extraction unit 4. It is formed by flowing toward the exhaust port 23. This gas is called stop gas.
The gas introduction port 22 is supplied with a stop gas from the gas supply unit 20a, and the gas flowing out from the gas introduction port 22 and the debris generated in the EUV light source device 10 are exhausted from the exhaust port 23 by the gas exhaust unit 20b. .
The gas curtain by the stop gas includes a first decompression container (chamber 9) constituting the EUV light source device 10, and a second decompression container (exposure machine housing 30) having an internal pressure lower than that of the first decompression container. And prevents debris generated in the EUV light source device 10 from entering the exposure device 31. Then, the debris and the stop gas that are prevented from advancing by the stop gas are exhausted from the opposing exhaust port 23.

FIG. 2 is a diagram illustrating a configuration example of a gas supply unit and a gas exhaust unit for forming a gas curtain.
The gas supply means includes a gas supply unit 20a and a gas inlet 22 having a nozzle 22a. The gas supply unit 20a includes, for example, a gas cylinder 25a that is a gas source of a stop gas, a pressure adjustment valve 25b that adjusts the pressure of the supplied gas, a pressure gauge 25c, and a stop valve 25d that turns the gas flow on and off. The stop gas supplied from the supply unit 20a blows out from the nozzle 22a.
As will be described later with reference to FIG. 4, the flow rate of the stop gas is adjusted when the stop gas is continuously supplied at a rate of about 10% even during the burst operation or when the supply of the stop gas is gradually reduced. In this case, a valve having a flow rate adjusting function may be used instead of the stop valve 25d.

As described above, hydrogen that absorbs less EUV light or a rare gas (He, Ne, Ar, Kr, etc.) having no reactivity is used as the stop gas.
As shown in FIG. 6, the gas exhaust means includes a gas exhaust port 23 having a diffuser 23a and a gas exhaust unit 20b. The exhaust unit 20b is, for example, an exhaust pump. The diffuser 23a is provided to face the nozzle 22a. The stop gas blown out from the nozzle 22a is sucked into the diffuser 23a and exhausted from the exhaust pump.
In the present embodiment, control such as opening / closing operation of the stop valve 25d of the gas supply unit 20a is performed by the control unit 40.

Next, the operation of the EUV light source apparatus of the present invention will be described.
In an exposure apparatus equipped with an EUV light source device, wafer exposure is performed in the following procedure. (1) In the exposure machine 31, the wafer is placed on a processing stage (not shown) held at the time of exposure. The wafer is divided into a plurality of exposure areas. As the processing stage moves, the wafer moves to a position where the first exposure area is exposed.
(2) When the control unit 40 of the EUV light source apparatus receives a notification that the wafer has moved to the exposure position from an exposure unit control unit (not shown) that controls the exposure unit, the control unit 40 receives first and second from the pulse power source 15. Pulse electric power is supplied to the discharge electrodes 11 and 12 to generate a pulse discharge and emit EUV light. That is, as described above, the EUV light source device is caused to perform a burst operation.
As a result, the EUV light from the EUV light source device is irradiated to the first exposure region of the wafer while being scanned, and the pattern is exposed.
(4) When the exposure device control unit is notified that the pattern exposure is completed, the control unit 40 stops the irradiation of the EUV light. When the EUV light irradiation stops, the processing stage moves in the exposure machine 31, and the wafer moves to a position where the second exposure area is exposed.
(5) In the exposure machine 31, the EUV light is irradiated to the second exposure area in the same manner as described above, and the pattern is exposed.
(6) By repeating this, when the entire exposure area of the wafer is exposed, the wafer is replaced with the next wafer.

When the EUV light is irradiated onto the wafer, a discharge is generated in the discharge unit 1 of the EUV light source device 10, and the EUV light is emitted. At the same time, debris is also generated as described above, so that the EUV light extraction unit 4 is supplied with a stop gas sufficient to stop the entry of the debris into the exposure device 31 to form a gas curtain.
However, when the wafer is moved to the next exposure area or when the wafer is replaced with the next wafer, the discharge is stopped and the generation of EUV light is stopped. At this time, no debris is generated from the discharge part 1. Therefore, the control unit 40 stops the supply of the stop gas or reduces the supply amount. The exhaust unit 20b desirably operates even when the supply of the stop gas is stopped, so that debris and the like in the chamber 9 can be discharged even when the burst operation is stopped.

FIG. 3 is a time chart showing the operation timing of the operation of the gas curtain and the burst operation, showing the timing of discharge (EUV emission) (burst operation timing) and the timing of ON / OFF of the supply of stop gas. 3A shows the ON / OFF operation of the gas curtain, and FIG. 3B shows the discharge (burst operation).
In the discharge unit 1, as described above, pulsed EUV light is generated by pulse discharge with a frequency of 10 kHz, for example. The wafer is divided into a plurality of exposure areas, and EUV light is sequentially scanned and exposed for each exposure area.
When one exposure area is exposed, discharge is continuously performed at a frequency of 10 kHz, and EUV light is emitted in accordance with the discharge. This is called a burst operation. When the EUV light is generated by the burst operation of the discharge, the control unit 40 opens the stop valve 25d (see FIG. 2) and supplies the stop gas, and the opening (communication) of the light extraction unit 4 of the EUV light source device 10 is supplied. Gas is allowed to flow across the hole 21) to form a gas curtain (ON in the figure).
When the irradiation of the EUV light to one exposure region is finished, the discharge is stopped (burst operation is stopped) and the emission of the EUV light is also stopped. At the same time, the work moves so that the next area is exposed, and when the movement is finished, the burst operation is resumed and EUV light is generated to perform exposure. During this burst operation and between burst operations (between EUV light generation and EUV light generation), the control unit 40 closes the stop valve 25d and stops the supply of stop gas (OFF).

The movement of the wafer ends in about 1 second, and the discharge unit 1 resumes the burst operation to generate EUV light, and performs the exposure process for the next exposure region. At the same time, the control unit 40 opens the stop valve 25d to supply a stop gas to form a gas curtain (ON). This is repeated until the exposure of one wafer is completed.
When the exposure processing of one wafer is completed, the wafer is taken out from the processing stage of the exposure machine 31, and the next wafer is placed on the processing stage. During the wafer exchange, the discharge is stopped and EUV light is not emitted. Therefore, the control unit 40 also closes the stop valve 25d at this time, stops the supply of the stop gas, and does not form the gas curtain.
In this way, by reducing the gas supply amount between the burst operations less than the supply amount during the burst operation, the total amount of gas supplied as the gas curtain is reduced, and the pressure in the EUV light source device is set to a desired value. It becomes easy to maintain at (about 1 Pa). Further, the amount of stop gas flowing into the exposure machine can be reduced.
Furthermore, in this embodiment, the apparatus configuration can be simplified.

4A and 4B are time charts showing other operation examples of the gas curtain and burst operation.
FIG. 4A shows a case where the stop gas continues to flow at a rate of, for example, about 10% with respect to the flow rate of the stop gas during the burst operation, and FIG. 4B is slightly delayed from the stop of the burst operation. The operation example in the case of gradually decreasing the supply of stop gas is shown. (A) shows the operation of the gas curtain, and (b) shows the discharge (burst operation).
Even if the burst operation is stopped, the debris in the chamber 9 of the EUV light source device does not immediately disappear, but the debris is floating in the chamber 9 for a while.
As shown in FIG. 4A, the stop gas is kept flowing even while the burst operation is stopped, or the burst operation is stopped for a while after the burst operation is stopped as shown in FIG. 4B. In addition, debris and the like remaining in the chamber can be prevented from entering the exposure apparatus. In FIG. 4B, as shown in FIG. 4A, a small amount of stop gas may continue to flow even while the burst operation is stopped.

  In the above, the present invention is applied to a LADPP type EUV light source device in which solid or liquid tin or lithium supplied to the surface of the electrode where discharge occurs is irradiated with an energy beam such as a laser to vaporize and then high temperature plasma is generated by discharge. However, the present invention is not limited to the DPP type EUV light source device that emits EUV light from the high-temperature plasma generated by the discharge between the electrodes without irradiating the laser beam as described above, The present invention can be similarly applied to an LPP-type EUV light source device that emits EUV light from high-temperature plasma generated by irradiating tin or lithium with an energy beam such as a laser.

DESCRIPTION OF SYMBOLS 1 Discharge part 2 EUV condensing mirror 3 Foil trap 4 EUV light extraction part 5 Laser irradiation machine 6 Motor 7 EUV light incident part 8 Exhaust unit 9 Chamber 10 EUV light source device 11 First discharge electrode 12 Second discharge electrode 13 Insulation Material 14 Raw material supply unit 15 Pulse power power supply 20a Gas supply unit 20b Gas exhaust unit 21 Communication hole 22 Gas inlet 22a Nozzle 23 Gas exhaust 23a Diffuser 25a Gas cylinder 25b Pressure adjustment valve 25c Pressure gauge 25d Stop valve 30 Exposure machine housing 31 Exposure unit 40 controller

Claims (2)

The first pressure reducing container provided with the extreme ultraviolet light generating unit that generates extreme ultraviolet light by the burst operation and the extreme ultraviolet light emitted from the first container are incident, and the internal pressure from the first pressure reducing container is A low second decompression vessel,
The first decompression vessel and the second decompression vessel are connected via a partition wall having an opening through which extreme ultraviolet light passes,
An extreme ultraviolet light source device provided with a gas supply means for supplying a gas for forming a gas curtain and a gas exhaust means for exhausting the supplied gas on the side where the extreme ultraviolet light is incident on the opening. ,
The extreme ultraviolet light source device characterized in that the gas supply amount from the gas supply means is controlled so as to increase the gas supply amount during the burst operation in synchronization with the burst operation in the extreme ultraviolet light generation unit . 2. The extreme ultraviolet light source device according to claim 1, wherein the supply of gas from the gas supply means is stopped while the generation of extreme ultraviolet light between the burst operations is stopped.

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