JP6075096B2 - Foil trap and light source device using the foil trap - Google Patents

Description

  The present invention relates to a foil trap that protects a condensing mirror and the like from debris emitted from high-temperature plasma, which is an extreme ultraviolet light source, and a light source device using the foil trap.

  As semiconductor integrated circuits are miniaturized and highly integrated, exposure light sources have become shorter in wavelength, and as a next-generation semiconductor exposure light source, in particular, extreme ultraviolet light with a wavelength of 13.5 nm (hereinafter referred to as EUV (Extreme Ultra Violet)). Development of an extreme ultraviolet light source device (hereinafter also referred to as an EUV light source device) that emits light) is underway.

There are several known methods for generating EUV light in an EUV light source device. One of them is a method of generating high-temperature plasma by heating and exciting extreme ultraviolet light radiation species (hereinafter referred to as EUV radiation species). There is a method for extracting EUV light from this high-temperature plasma.
EUV light source devices that employ such a method are largely divided into LPP (Laser Produced Plasma) EUV light source devices and DPP (Discharge Produced Plasma) EUV light source devices, depending on the high temperature plasma generation method. Divided.

[DPP EUV light source device]
FIG. 6 is a diagram for simply explaining the DPP-type EUV light source device described in Patent Document 1. In FIG.
The EUV light source apparatus has a chamber 1 that is a discharge vessel. In the chamber 1, an EUV condensing unit that houses a discharge unit 1 a that houses a pair of disc-shaped discharge electrodes 2 a and 2 b, a foil trap 5, an EUV condensing mirror 6 that is a condensing optical means, and the like. Part 1b.
1c is a gas exhaust unit for exhausting the discharge part 1a and the EUV condensing part 1b to make the inside of the chamber 1 into a vacuum state.
2a and 2b are disk-shaped electrodes. The electrodes 2a and 2b are separated from each other by a predetermined interval, and the rotation motors 16a and 16b rotate to rotate about the rotation axes 16c and 16d, respectively.
Reference numeral 14 denotes a high-temperature plasma raw material that emits EUV light having a wavelength of 13.5 nm. The high-temperature plasma raw material 14 is heated molten metal, for example, liquid tin (Sn), and is accommodated in the containers 15a and 15b.

The electrodes 2a and 2b are arranged so that a part of the electrodes 2a and 2b is immersed in a container 15 that accommodates the high temperature plasma raw material 14. The liquid high-temperature plasma raw material 14 placed on the surfaces of the electrodes 2a and 2b is transported to the discharge space as the electrodes 2a and 2b rotate. The high temperature plasma raw material 14 transported to the discharge space is irradiated with laser light 17 from a laser source 17a. The high temperature plasma raw material 14 irradiated with the laser beam 17 is vaporized.
After the pulse voltage is applied to the electrodes 2a and 2b from the power supply means 3, the high-temperature plasma raw material 14 is vaporized by the irradiation of the laser light 17, whereby a pulse discharge starts between the electrodes 2a and 2b. Plasma P is formed by the plasma raw material 14. When the plasma is heated and excited by a large current flowing at the time of discharge, the EUV is emitted from the high temperature plasma P.
The EUV light radiated from the high temperature plasma P is collected by the EUV collector mirror 6 at a condensing point (also referred to as an intermediate condensing point) f of the condensing mirror 6, emitted from the EUV light extraction unit 7, and sent to the EUV light source device. The light enters the exposure device 40 indicated by the connected dotted line.

  The EUV collector mirror 6 generally has a structure in which a plurality of thin concave mirrors are arranged with high precision in a nested manner. The shape of the reflecting surface of each concave mirror is, for example, a spheroidal shape, a rotating parabolic shape, or a Walter shape, and each concave mirror is a rotating body shape. Here, the Walter shape is a concave shape in which the light incident surface is composed of a rotation hyperboloid and a rotation ellipsoid, or a rotation hyperboloid and a rotation paraboloid in order from the light incident side.

[LPP EUV light source device]
FIG. 7 is a diagram for simply explaining an LPP type EUV light source apparatus.
The LPP type EUV light source apparatus has a chamber 1. The chamber 1 is provided with a raw material supply unit 10 and a raw material supply nozzle 20 for supplying a raw material (high temperature plasma raw material) which is an EUV radiation species. From the raw material supply nozzle 20, for example, droplet-shaped tin (Sn) is released as a raw material.
The inside of the chamber 1 is maintained in a vacuum state by a gas exhaust unit 1c configured by a vacuum pump or the like.

A laser beam (laser beam) 22 from an excitation laser beam generator 21 which is a laser beam irradiation unit is introduced into the chamber 1 through a laser beam incident window 23 while being collected by a laser beam focusing unit 24. The raw material (for example, droplet-shaped tin) emitted from the raw material supply nozzle 20 is irradiated through a laser beam passage hole 25 provided in a substantially central portion of the EUV collector mirror 8. The excitation laser beam generation device 21 used here is, for example, a pulse laser device with a repetition frequency of several kHz, and a carbon dioxide (CO ₂ ) laser, a YAG laser, or the like is used.

  The raw material supplied from the raw material supply nozzle 20 is heated and excited by irradiation with the laser beam 22 to become plasma, and EUV light is emitted from this plasma. The emitted EUV light is reflected by the EUV collector mirror 8 toward the EUV light extraction unit, is collected at the condensing point (intermediate condensing point) of the EUV collector mirror, and is emitted from the EUV light extraction unit 7. Then, the exposure device 40 indicated by a dotted line connected to the EUV light source device enters.

Here, the EUV collector mirror 8 is a spherical reflecting mirror coated with, for example, a multilayer film of molybdenum and silicon. Depending on the arrangement of the excitation laser light generating device 21 and the laser light incident window 23, the laser light The passage hole 25 may not be required.
Further, the laser beam 22 for plasma generation may reach the EUV light extraction unit as stray light. Therefore, a spectral purity filter (not shown) that transmits EUV light and does not transmit laser light 22 may be disposed in front of the EUV light extraction unit (plasma side).

[Foil trap]
In the EUV light source device described above, various debris is generated from the plasma P. This is caused by, for example, debris such as metal powder generated by sputtering of the metal (for example, a pair of disc-shaped discharge electrodes 2a, 2b) in contact with the plasma P or Sn, which is the high-temperature plasma raw material 14. Debris.
These debris obtains large kinetic energy through the process of plasma contraction and expansion. That is, the debris generated from the plasma P is ions or neutral atoms that move at high speed. Such debris hits the EUV collector mirror, scrapes the reflecting surface, or deposits on the reflecting surface, and EUV. Reduces light reflectivity.

  Therefore, for example, in the EUV light source device shown in FIG. 6, in order to prevent damage to the EUV collector mirror 6 between the discharge unit 1a and the EUV collector mirror 6 accommodated in the EUV light collector 1b, a foil is used. A trap 5 is installed. The foil trap 5 functions to capture debris as described above and allow only EUV light to pass through.

An example of the foil trap is shown in Patent Literature 2 and Patent Literature 3, and is described as “Foil Trap” in Patent Literature 3.
FIG. 8 shows a schematic configuration of a foil trap as disclosed in Patent Document 2.
The foil trap 5 is composed of a plurality of thin films (foil) or thin flat plates (plates) (hereinafter referred to as radial plates) radially arranged around the central axis of the foil trap 5 (FIG. 8 coincides with the optical axis of EUV light). The thin film and the flat plate are collectively referred to as “foil 5a”, and support for the cone-shaped central column 5c and outer ring 5b made of molybdenum (Mo) alloy or the like arranged concentrically to support the plurality of foils 5a. It is composed of the body.
The foil 5a is arranged and supported so that its plane is parallel to the optical axis of the EUV light. Therefore, looking at the foil trap 5 from extreme ultraviolet light source (a high temperature plasma P) side, except for the portion of the centered post 5 c and the outer ring 5 b of the support, only visible thickness of the foil 5a. Therefore, most of the EUV light from the high temperature plasma P can pass through the foil trap 5.

  On the other hand, the plurality of foils 5a of the foil trap 5 function to increase the pressure by decreasing the conductance of the portion by finely dividing the arranged space. Therefore, the speed of debris from the high temperature plasma P decreases because the collision probability increases in a region where the pressure is increased by the foil trap 5. Some debris with reduced speed is captured by the foil 5a and the foil supports 5b and 5c.

In the DPP EUV light source device, light on the optical axis (light emitted from the high-temperature plasma P at an angle of 0 ° (radiation angle is 0 °)) or a concave surface located on the innermost side of the EUV collector mirror 6 Light that is incident on the EUV collector mirror 6 at an incident angle smaller than the incident angle that can be reflected by the mirror (hereinafter also referred to as the minimum incident angle) is not used for the exposure and is preferably not present. Therefore, centered post 5c is no problem even if present, is also possible to shield more aggressively centered arm 5c rather. Incidentally centered arms 5c, since a shape for blocking the minimum incident angle or less of the light is determined from the configuration of the EUV focusing mirror 6, is generally a cone shape. Therefore, hereinafter, the centered post also called cone (cone).
In addition, since the foil trap is disposed near the high temperature plasma, the heat load received is also large. Therefore, the foil and cone constituting the foil trap are formed of a high heat resistant material such as molybdenum (Mo), for example.

  The above-described foil trap is often employed mainly for DPP type EUV light source devices. In the case of an LPP type EUV light source device, the collision direction to the EUV collector mirror is controlled by controlling the debris traveling direction by a magnetic field, or the debris adhering to the EUV collector mirror is removed by a cleaning gas such as hydrogen gas. doing. However, as shown in FIG. 7, a foil trap as described above may be disposed between the high temperature plasma and the EUV collector mirror. That is, the foil trap can be employed not only in the DPP type EUV light source device but also in the LPP type EUV light source device.

[Rotating foil trap, fixed foil trap]
In recent years, as described in Patent Document 4, two foil traps are provided in series, and one foil trap is rotated.
FIG. 9 shows a schematic configuration. In the example shown in FIG. 9, the foil trap 4 closer to the high temperature plasma P has a function of rotating. Hereinafter, the foil trap having the rotation function is also referred to as a rotary foil trap 4, and the non-rotating fixed foil trap 5 is also referred to as a fixed foil trap 5. In FIG. 9, a rotary foil trap 4 is provided on the plasma P side between the EUV collector mirror 6 and the plasma P, and a fixed foil trap 5 is provided between the rotary foil trap 4 and the EUV collector mirror 6. It has been. The fixed foil trap 5 is the same as that shown in FIG. In FIG. 9, the outer ring 5b of the fixed foil trap 5 is omitted.

Rotating foil trap 4, centered strut (cones) 4c is connected to the rotary shaft and coaxial rotary drive mechanism (not shown). When the rotary shaft of the rotary drive mechanism rotates, the rotary foil trap 4 rotates around the rotary shaft of the cone 4c.
Each foil 4a of the rotary foil trap 4 is fixed to the cone 4c by, for example, brazing using a gold braze (see brazing portion 4b in FIG. 9), and each foil 4a is centered on the rotation axis of the cone 4c. It grows radially.
In the rotary foil trap 4, the foil 4a only needs to be fixed to the cone 4c, and therefore the outer ring 5b as shown in FIG. 9 need not be provided.

  The rotary foil trap 4 captures debris flying from the plasma P when a plurality of foils 4a rotate around the rotation axis of the cone. For example, debris caused by Sn which is the high temperature plasma raw material 14 is captured by each foil of the rotary foil trap 4 or deflected so that the traveling direction is different from the EUV collector mirror 6 side. That is, accumulation of debris on each concave mirror of the EUV collector mirror 6 is suppressed by using the rotary foil trap 4.

Here, as described above, since the rotary foil trap 4 faces the high temperature plasma P, it is heated by the high temperature plasma P or heated by debris collision. Therefore, the heat load received by the rotary foil trap 4 is high.
Therefore, the rotary foil trap 4 cools the cone 4c by providing a cooling pipe inside the cone 4c and flowing a coolant such as water through the cooling pipe. Since the foil 4a is thermally connected to the cone 4c by brazing or the like, the foil is also cooled by cooling the cone 4c.

  The fixed foil trap 5 captures debris that travels at a high speed that could not be captured by the rotary foil trap 4. Since the debris collision probability increases in the region where the pressure is increased by the fixed foil trap 5, the speed of the debris moving at a high speed decreases. Some debris with reduced speed is captured by the foil 5a and the foil supports 5b and 5c. That is, sputtering by high-speed debris of each concave mirror of the EUV collector mirror 6 is suppressed by using the fixed foil trap 5. If necessary, the cone 5c of the fixed foil trap 5 may be cooled.

Special table 2007-505460 gazette JP-T-2002-504746 Special table 2004-214656 gazette Special table 2012-513653 gazette

The cone portion 5c facing the plasma P when the fixed foil trap 5 shown in FIG. 6 is provided, or the cone facing the plasma P when the rotating foil trap 4 shown in FIG. 9 is provided. The portion 4c has a very short distance to the plasma P, which is a light emitting point, and is always exposed to debris (high-speed particles) moving at high speed from the plasma P, and wear (erosion) due to collision of the high-speed particles occurs. To do.
When erosion occurs, the foil trap itself may need to be replaced, increasing the maintenance frequency of the foil trap.

In addition, the foil trap disposed opposite to the high-temperature plasma has a large heat load during the operation of the EUV light source device, and is heated to 500 to 700 ° C. or more depending on the input energy to the plasma.
In the rotary foil trap 4, as described above, each foil 4a is fixed to the cone 4c by brazing or the like. As the hard brazing used for brazing, a relatively high heat-resistant gold brazing is used. doing. However, when high-temperature debris due to tin (Sn), which is a high-temperature plasma raw material, adheres to this brazed portion, a chemical reaction occurs between the hard solder (gold solder) and tin (Sn), and the hard solder to degrade.
The deteriorated hard solder has a lower mechanical strength than the original hard solder. For this reason, as shown in FIG. 10, for example, when the rotating foil trap 4 is rotating, there is a problem that the brazing portion 4b is detached by the centrifugal force applied to the foil 4a and the rotating foil trap is damaged.
The present invention has been made in view of the above-described circumstances, and the problem is that the maintenance of the fixed foil trap and the rotary foil trap can be facilitated and the frequency thereof can be reduced. The object is to provide a foil trap that can avoid the problem that the foil is detached from the foil trap due to the debris adhering to the hard brazing to be fixed.

As described above, the central strut (cone) of the foil trap is always exposed to debris (high-speed particles) moving at a high speed from the plasma, thereby causing erosion. Therefore, if a replaceable shield member is attached to the side of the central column facing the above debris, when the erosion occurs, it is not necessary to replace the foil trap itself if the shield member is replaced. become.
However, it has been found that when the temperature of the shield member rises, erosion in the high temperature portion of the shield member rapidly proceeds and the replacement frequency of the shield member increases. For this reason, it is desirable to be able to cool the shield member effectively.
In the present invention, the shield member is provided as described above, and an intermediate member that is softer and heat conductive is inserted between the shield member and the cone, and the material constituting the shield member and the member constituting the cone are soft. To do.
Thereby, the heat of a shield member can be effectively transmitted to a cone, the temperature rise of a shield member can be suppressed, and the replacement frequency of a shield member can be decreased.
Moreover, the said shield member is set to the magnitude | size which the said brazing part is shielded from plasma.
As a result, it is possible to prevent the deterioration of the hard brazing caused by the high temperature debris adhering to the brazed portion, and it is possible to prevent the occurrence of the problem that the rotary foil trap is broken.
That is, in the present invention, the above problem is solved as follows.
(1) It is disposed between a plasma and a collecting mirror that collects light emitted from the plasma, and includes a plurality of foils extending radially from a main axis, and the light passes through but debris from the plasma is captured. The foil trap is supported by a central support column disposed on the main shaft, the central support column is cooled by a cooling mechanism, and a shield member is provided on the surface of the central support column facing the plasma An intermediate member made of a material softer than both the material constituting the shield member and the material constituting the intermediate ring. Provide. The plurality of foils are brazed to and supported by a central column disposed on the main shaft, and the shield member is sized to shield the brazed portion from the plasma.
( 2 ) A vessel, a plasma raw material supply means for supplying a plasma raw material into the vessel, a discharge member comprising a pair of discharge electrodes for heating and exciting the plasma raw material to generate plasma, and radiated from the plasma A condensing mirror for condensing light, a foil trap provided between the discharge member and the condensing mirror, a light extraction portion formed in the container for extracting the condensed light, and the inside of the container In the light source device provided with the exhaust means for exhausting the air and adjusting the pressure in the container, the foil trap of (1) is used as the foil trap.
( 3 ) a container, plasma raw material supply means for supplying a plasma raw material into the container, laser beam irradiation means for irradiating the plasma raw material with a laser beam to heat and excite the plasma raw material to generate high temperature plasma, , A light collecting mirror for condensing light emitted from the plasma, a foil trap provided between the high temperature plasma and the light collecting mirror, and light formed in the container for taking out the condensed light. in the light source device, comprising: a take-out portion, and an exhaust means for adjusting the pressure in the evacuated container to the container, the foil trap uses a foil trap (1).

In the present invention, the following effects can be obtained.
(1) Since a replaceable shield member is provided on the surface of the foil trap center column facing the plasma, even if wear (erosion) occurs due to high-speed debris (high-speed particles), only the shield member is used. If it is replaced, it is not necessary to replace the foil trap itself, and maintenance can be facilitated.
In particular, by providing an intermediate member between the shield member and the central support column and capable of transferring heat and made of a material softer than both the material constituting the shield member and the material constituting the intermediate ring, the shield Heat transfer from the member to the central column is performed well, and the shield member can be effectively cooled. For this reason, the rapid progress of the erosion in the high temperature part of a shield member can be suppressed, the replacement frequency of a shield member can be decreased, and a maintenance can be made easy.
(2) The shield member has a structure in which the brazed portion of the foil and the central column is shielded against the debris made of tin (Sn) flying from the high-temperature plasma, so that the debris is the brazed portion. It will not adhere to. For this reason, deterioration of the hard brazing material is suppressed. For this reason, in a rotary foil trap, the malfunction that the joining in a brazing part breaks can be prevented.

It is a figure which shows schematic structure of the 1st Example of this invention. It is a figure explaining attachment of the shield member to a cone in a rotary foil trap. It is a figure explaining the intermediate member provided between the shield member and the cone. It is a figure which shows the example applied to the fixed type foil trap . It is a figure explaining attachment to the cone of a shield member in a fixed type foil trap. It is a figure explaining simply a DPP type EUV light source device. It is a figure explaining simply the LPP type EUV light source device. It is a figure which shows schematic structure of a foil trap. It is a figure explaining a rotary foil trap. It is a figure explaining a mode that a brazing part remove | deviates and foil is scattered.

It shows a schematic configuration of an embodiment of the present invention in FIG. In this embodiment, the present invention is applied to the rotary foil trap.
In the figure, the foil trap 4 closer to the high-temperature plasma P is a rotating foil trap having a rotating function as described above, and a fixed foil trap between the rotating foil trap 4 and the EUV collector mirror 6. 5 is provided.

Rotating foil trap 4, as described above, the cone (middle center strut) 4c is connected to the rotary shaft and coaxial rotation mechanism which is not shown, the rotary shaft of the rotary mechanism is rotated, the rotary foil trap 4 rotates around the rotation axis of the cone 4c.
Each foil 4a of the rotary foil trap 4 is fixed to the cone 4c by brazing using, for example, a gold brazing, at the brazing portion 4b as described above. Each foil 4a extends radially about the rotation axis of the cone 4c.
In the rotary foil trap 4 of the present embodiment, a plate-like shield member 4d made of a high heat resistant material such as molybdenum (Mo) or tungsten (W) is disposed on the surface of the cone 4c facing the high temperature plasma. .
Compared with both the material constituting the shield member 4d and the member constituting the cone 4c, as shown in FIG. 3 to be described later, between the flat surface of the shield member 4d and the upper surface of the cone 4c. A soft and heat transferable intermediate member 4e is inserted.
The size of the shield member 4d is set to a size that can shield the brazed portion 4b between the cone 4c and the foil 4a from the high temperature plasma, and the brazed portion 4b has a plate shape from the direction facing the position of the high temperature plasma. The shield member 4d cannot be seen.
That is, the diameter of the shield member 4d is larger than the diameter of the cone 4c in contact with the shield member 4d, and the difference between the diameter of the shield member and the diameter of the central column on the surface facing the plasma is the center of the brazing braze. The height is greater than the height of the exposed part from the column.
The cone 4c is disposed in a region shielded from the direction facing the position of the high temperature plasma, and the shape thereof is preferably a cylindrical shape or a truncated cone shape, particularly a truncated cone shape.

By configuring the size of the shield member 4d as described above, debris made of tin (Sn) flying from high-temperature plasma collides with the plate-like shield member 4d, but does not contact the plate-like shield member 4d. By being blocked, it will not adhere directly to the brazed portion 4b between the cone 4c and the foil 4a.
Therefore, in a state where the foil trap 4 is heated to a high temperature (500 to 700 ° C.), a chemical reaction between the brazing material (gold brazing) and tin (Sn) is avoided, and the above-mentioned hard coating is avoided. The mechanical strength of the wax is maintained. Therefore, in the rotating foil trap 4, during the rotation of the foil trap 4, it is possible to prevent a problem that the joint at the brazed portion is broken due to the deterioration of the brazed portion 4b.

Here, it is desirable that the shield member 4 d has a shape that shields light having a minimum incident angle or less determined from the configuration of the EUV collector mirror 6. That is, it is preferable that the effective EUV light collected by the EUV collector mirror 6 is sized so as not to block as much as possible.
Therefore, the shape of the cone 4c (cone) arranged behind the shield member 4d (on the EUV emission side) is relatively more than the cone shape that shields light having a minimum incident angle or less determined from the configuration of the conventional EUV collector mirror. Becomes smaller.

  By the way, as described above, the cone 4c portion that fixes the foil 4a of the rotating foil trap 4 to the rotating shaft has a very short distance to the plasma P that is a light emitting point. For this reason, the shield member 4d attached to the cone 4c is always exposed to debris (high-speed particles) moving at high speed from the plasma, and wear (erosion) due to collision of the high-speed particles occurs.

  Therefore, by providing a structure in which the shield member 4d can be exchanged for the cone 4c, the rotating foil trap 4 itself associated with erosion need not be exchanged. Therefore, there is an effect that the maintenance frequency of the rotating foil trap 4 is reduced.

  Here, it has been found by the inventors' experiments that when the temperature of the shield member 4d increases as the input power to the high-temperature plasma increases, erosion in the high-temperature portion of the shield member 4d rapidly proceeds. That is, when the temperature of the shield member 4d rises, the replacement frequency of the shield member 4d accompanying erosion increases. Therefore, in order to increase the input power to the high temperature plasma in order to obtain high output EUV radiation, it is preferable to cool the shield member 4d.

As described above, the cone 4c of the rotating foil trap 4 is cooled by the cooling mechanism (not shown). Therefore, it is desirable to attach the shield member to the cone 4c in an exchangeable manner so that the upper surface portion (surface facing the high temperature plasma) of the cone 4c and the flat portion of the plate-like shield member 4d are in contact with each other.
In the example shown in FIG. 2, two screw holes 4f are provided on the upper surface side of the cone 4c, two through holes 4g are provided in the shield member 4d, and fixing screws 4h that pass through the through holes 4g are screw holes 4f. The shield member 4d and the cone 4c are fixed by fitting to each other. Since the fixing screw 4h is also required to have high heat resistance, the fixing screw 4h is made of, for example, molybdenum (Mo).
Note that if the tightening force by the screw 4h is increased and the pressing force of the shield member 4d against the cone 4c is increased, the heat transfer from the shield member 4d to the cone 4c is improved, but molybdenum which is the material of the cone 4c and the screw 4h. High heat-resistant materials such as (Mo) and tungsten (W) have high hardness and are brittle, so that they are difficult to work and easily cracked, and it is difficult to increase the pressing force by the screws 4h.

Here, as shown in FIG. 3A, there is actually a certain degree of surface roughness on the surface of the flat surface portion of the shield member 4d and the surface of the upper surface portion of the cone 4c. Therefore, the contact area when the flat surface portion of the shield member 4d and the upper surface portion of the cone 4c are brought into contact with each other is reduced due to the surface roughness. Therefore, when the temperature of the shield member that has been heated to the cooled cone 4c side is heat-exchanged by heat conduction, the efficiency is poor due to the small contact area.
Therefore, when the input to the high-temperature plasma becomes large, the shield member is arranged so that the upper surface portion of the cone 4c cooled by a cooling mechanism (not shown) and the flat portion of the plate-like shield member 4d come into contact with each other. Even if it is attached to the cone 4c, the shield member may not be sufficiently cooled.

In order to avoid such a problem, in the present invention, as shown in FIG. 3B, a shield member 4d is formed between the flat surface of the shield member 5d and the upper surface of the cone 4c. The intermediate member 4e, which is softer and heat transferable than both the material to be formed and the member constituting the cone 4c, is inserted.
Thereby, heat transfer from the shield member 4d to the cone 4c can be performed satisfactorily, the shield member 4d can be effectively cooled, and the temperature rise of the shield member 4d can be suppressed. For this reason, rapid progress of the erosion in the high temperature part of the shield member 4d can be suppressed, and the replacement frequency of the shield member 4d can be reduced.
Here, in FIG. 3, in order to facilitate understanding, a fixing screw for attaching the shield member to the cone 4c, a through hole of the shield member, and a screw hole of the cone 4c are omitted. The intermediate member 4e is also actually provided with a through hole through which the screw portion of the fixing screw passes.

That is, when the shield member 4d and the cone 4c are attached using the fixing screw 4h via the intermediate member 4e, a force is applied in the direction from the shield member 4d toward the cone 4c. At this time, since the intermediate member 4e is softer than the material constituting the shield member 4d, the surface of the intermediate member 4e that contacts the shield member 4d is deformed corresponding to the surface roughness of the contact surface of the shield member 4d. Moreover, since the intermediate member 4e is softer than the material which comprises the cone 4c, the surface which contacts the cone 4c of the intermediate member 4e deform | transforms according to the surface roughness of the contact surface of the cone 4c. Therefore, the contact area between the shield member 4d and the intermediate member 4e and the contact area between the intermediate member 4e and the cone 4c are larger than the contact area when the shield member 4d and the cone 4c are contacted except for the intermediate member 4e. . Therefore, when the intermediate member 4e is made of a material capable of transferring heat, the thermal conductivity between the shield member 4d and the cone 4c is substantially improved, and the shield member 4d can be sufficiently cooled.
Therefore, the progress of erosion of the shield member 4d can be suppressed, and the replacement frequency of the shield member 4d can be reduced.
As a specific material of the intermediate member 4e, graphite, copper, brass, and aluminum are adopted, and graphite is particularly preferable.

The case where the present invention is applied to the rotary foil trap has been described above . FIG. 4 shows a case where the present invention is applied to the fixed foil trap.
In FIG. 2A, a fixed foil trap 5 is provided between the high temperature plasma P and the EUV collector mirror 6. The fixed foil trap 5 is, for example, the same as that shown in FIG. 9, and the outer ring 5b of the fixed foil trap 5 is omitted in FIG.
A plate-like shield member 5d made of a high heat resistant material such as molybdenum (Mo) or tungsten (W) is replaceably attached to the surface of the fixed foil trap 5 facing the high temperature plasma P of the cone 5c.

Here, in the fixed foil trap 5, it is not always necessary to firmly fix the foil to the cone (center column) like the rotary foil trap, and the foil 5a is not usually fixed to the cone 5c by brazing. .
Therefore, in such a fixed foil trap 5, the size of the shield member 5 d is made larger than the size of the surface of the cone 5 c facing the high temperature plasma as in the rotary foil trap 4. There is no need to be able to shield the brazed portion of the cone and foil. In the structure shown in FIG. 4, the diameter of the shield member 5d is set to be approximately equal to the diameter of the surface of the cone 5c facing the high temperature plasma.
As shown in FIG. 5, for example, as shown in FIG. 5, the shield member 5d has a fixing screw 5h that passes through two through holes 5g provided in the shield member 5d fitted into the screw hole 5f of the cone 5c. Thus, the cone 5c is fixed.

Further, as shown in FIG. 4B, between the flat surface of the shield member 5d and the upper surface of the cone 5c, both the material constituting the shield member 5d and the member constituting the cone 5c In comparison, the intermediate member 5e which is soft and capable of transferring heat is inserted.
As a result, heat transfer from the shield member 5d to the cone 5c is favorably performed, the shield member 5d can be effectively cooled, and the temperature rise of the shield member 5d can be suppressed.
For this reason, the rapid progress of the erosion in the high temperature part of the shield member 5d can be suppressed, and the replacement frequency of the shield member 5d can be reduced.

The foil trap of the present invention described above can be applied to any of the DPP EUV light source device shown in FIG. 6 and the LPP light source device shown in FIG. As shown in FIG. 1, both a rotary foil trap and a fixed foil trap can be provided, or only a fixed foil trap can be provided as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Chamber 1a Discharge part 1b EUV condensing part 1c Gas exhaust unit 2a, 2b Discharge electrode 3 Power supply means 4 Rotating foil trap 4a Foil 4b Brazing part 4c Cone (center support | pillar)
4d Shield member 4e Intermediate member 4h Fixing screw 5 Fixed foil trap 5a Foil 5c Cone (center strut)
5d Shield member 5e Intermediate member 5h Fixing screw 6, 8 EUV collector mirror 7 EUV light extraction unit 10 Raw material supply unit 14 High temperature plasma raw material 15 Containers 16a, 16b Rotating motors 16c, 16d Rotating shaft
17 Laser beam 17a Laser source 20 Raw material supply nozzle 22 Laser beam 21 Excitation laser beam generator 22 Laser beam (laser beam)
23 Laser beam incident window 24 Laser beam focusing means 40 Exposure machine P High temperature plasma

Claims (3)

A foil trap disposed between a plasma and a collecting mirror that collects light emitted from the plasma, and includes a plurality of foils extending radially from a main axis, and the light passes therethrough but traps debris from the plasma. Because
The plurality of foils are supported by a central column disposed on the main shaft, and the central column is cooled by a cooling mechanism,
In the foil trap in which a shield member is provided on the surface of the central column facing the plasma,
Between the shield member and the center pillar, a possible heat transfer, the intermediate member is provided, et al is made of a softer material than both the material constituting the material and the central post constituting the shield member,
The plurality of foils are supported by being brazed to a central column disposed on the main shaft,
The foil trap , wherein the shield member is sized to shield the brazed portion from the plasma. A vessel, a plasma source supply means for supplying plasma source into the vessel, a discharge member comprising a pair of discharge electrodes for heating and exciting the plasma source to generate plasma, and collecting light emitted from the plasma. A condensing mirror that emits light, a foil trap provided between the discharge member and the condensing mirror, a light extraction portion formed in the container for extracting the condensed light, and exhausting the inside of the container. In the light source device comprising an exhaust means for adjusting the pressure in the container,
It said foil trap comprises a light source device which is a foil trap according to claim 1. A plasma source supply means for supplying a plasma raw material into the container; a laser beam irradiation means for irradiating the plasma raw material with a laser beam to heat and excite the plasma raw material to generate a high temperature plasma; and the plasma A condensing mirror that condenses the light emitted from the foil, a foil trap provided between the high-temperature plasma and the condensing mirror, and a light extraction portion formed in the container for extracting the condensed light In the light source device comprising the exhaust means for exhausting the inside of the container and adjusting the pressure in the container,
It said foil trap comprises a light source device which is a foil trap according to claim 1.

Images