Plasma generating mechanism and light source device

Abstract

To provide a plasma generating mechanism and a light source device which are capable of suppressing failure by debris which occurs with plasma production.SOLUTION: A light source device is equipped with a plasma generating mechanism which takes out a radiation ray by converting liquid-state plasma raw material into plasma by emission of an energy beam, and comprises a rotor, a rotary drive source, a raw material supply part and a debris reflection surface. The rotor has a rotational surface being a surface rotating about a rotation axis. The rotary drive source rotates the rotor about the rotation axis. The raw material supply part supplies the plasma raw material to the rotor. The debris reflection surface is positioned in a normal direction of an irradiation position where the energy beam is emitted, and reflects debris entering from the irradiation position in a direction different from an incident route of the energy beam to the irradiation position.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a plasma generation mechanism and a light source device that supply a plasma raw material to an energy beam irradiation position and generate plasma.

Background Art

[0002] Conventionally, X-rays have been used in medical applications, industrial applications, and research applications. In the medical field, X-rays are used for applications such as chest X-ray imaging, dental X-ray imaging, and CT (Computer Tomogram). In the industrial field, X-rays are used for applications such as non-destructive inspection for observing the inside of substances such as structures and welded parts, and tomographic non-destructive inspection. In the research field, X-rays are used for applications such as X-ray diffraction for analyzing the crystal structure of substances and X-ray spectroscopy (fluorescent X-ray analysis) for analyzing the constituent elements of substances. Extreme ultraviolet light with a wavelength of 13.5 nm in the relatively long-wavelength soft X-ray region of X-rays (hereinafter also referred to as "EUV (Extreme Ultra Violet) light") has been used as exposure light in recent years.

[0003] Some EUV light source devices that generate EUV light generate high-temperature plasma by irradiating a plasma raw material such as molten tin or lithium with an energy beam to excite it, and extract EUV light from the high-temperature plasma. A method using laser light as the energy beam is called LPP (Laser Produced Plasma), and a method using discharge is called DPP (Discharge Produced Plasma) or LDP (Laser Assisted Discharge Produced Plasma).

[0004] As an EUV light source device using the LPP method, there is known one that generates plasma by exciting a raw material by condensing laser light on droplets of the plasma raw material. In contrast, in recent years, a method has been developed in which a plasma raw material is supplied to the laser light irradiation region by the centrifugal force of a rotating body (see, for example, Patent Document 1). In this method, the rotating body rotates while being immersed in the plasma raw material stored at the lower part, so that the plasma raw material adheres to the surface of the rotating body, and the plasma raw material is supplied to the irradiation region on the surface of the rotating body. Since this method does not require the plasma raw material to be supplied as droplets, it has a relatively simple configuration compared to the method of condensing laser light on droplets, and it is possible to obtain high-intensity radiation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when laser light is irradiated onto the plasma raw material, debris, which is the vapor and smoke of the plasma raw material, is generated together with the plasma. When laser light is irradiated onto the surface of the rotating body coated with the plasma raw material as described in Patent Document 1, a large amount of debris is ejected in the normal direction of the surface of the rotating body. Even if the rotating body is surrounded by a cover and the debris is sealed with the cover, the cover needs to have an opening for passing the laser light and EUV light.

[0007] If debris is released from this opening, there is a risk of causing problems such as adhering to external members and causing unnecessary conduction. Also, if debris adheres to the opening, the opening is narrowed, and the laser light and EUV light passing through the opening may be blocked or attenuated, resulting in a decrease in the output of EUV light. Furthermore, if debris floats near the opening, the EUV light may be absorbed by the debris, and there is also a risk of a decrease in the output of EUV light in this regard.

[0008] In view of the above circumstances, an object of the present invention is to provide a plasma generation mechanism and a light source device capable of suppressing problems caused by debris generated during plasma generation.

Means for Solving the Problems

[0009] To achieve the above object, a plasma generation mechanism according to one embodiment of the present invention is a plasma generation mechanism included in a light source device that converts a liquid plasma raw material into plasma by irradiating an energy beam and extracts radiation, and includes a rotating body, a rotation drive source, a raw material supply unit, and a debris reflecting surface. The rotating body has a rotating surface that rotates around a rotation axis. The rotation drive source rotates the rotating body around the rotation axis. The raw material supply unit supplies the plasma raw material to the rotating body. The debris reflecting surface is located in the normal direction of the irradiation position where the energy beam is irradiated, and reflects debris incident from the irradiation position in a direction different from the incident path of the energy beam to the irradiation position.

[0010] According to this configuration, when an energy beam is incident on the irradiation position and debris is generated at the irradiation position, the debris enters the debris reflecting surface located in the normal direction of the irradiation position and is reflected in a direction different from the incident path of the energy beam. As a result, the influence of the debris on the energy beam is suppressed, and a decrease in the output of the radiation is prevented.

[0011] The irradiation position may be located on the rotating surface.

[0012] The debris reflecting surface may reflect debris incident from the irradiation position in a direction different from the incident path of the energy beam to the irradiation position and the emission path of the radiation from the irradiation position.

[0013] The raw material supply unit has a storage tank for storing the plasma raw material. A part of the rotating surface of the rotating body may be immersed in the plasma raw material stored in the storage tank.

[0014] The apparatus further includes a cover that forms the storage tank and surrounds the rotating body. The debris reflecting surface may be such that the normal direction at each position on the debris reflecting surface faces inward of the cover.

[0015] The cover has an opening through which the energy beam passes. The debris reflecting surface may reflect debris incident from the irradiation position in a direction different from that of the opening.

[0016] The opening includes an incident port through which the energy beam passes and an emission port through which the radiation passes. The debris reflecting surface may face the irradiation position through the opening.

[0017] The cover has a facing surface facing the rotating surface. The debris reflecting surface may be the surface of a debris reflecting structure provided at a position on the facing surface that faces the irradiation position.

[0018] The debris reflecting surface may be the surface of a debris reflecting structure supported by a support member different from the cover.

[0019] At least a part of the debris reflecting surface may be curved.

[0020] The debris reflecting surface may be the surface of a rotating debris reflecting structure.

[0021] The radiation may be extreme ultraviolet light or X-rays.

[0022] The plasma raw material may be tin, lithium, gadolinium, terbium, gallium, bismuth, indium, or an alloy containing at least one of these materials.

[0023] To achieve the above object, a light source device according to an aspect of the present invention is a light source device that converts a liquid plasma raw material into plasma by irradiating an energy beam and extracts radiation, and includes a plasma generation mechanism and a beam source. The plasma generation mechanism includes a rotating body having a rotating surface that is a surface rotating around a rotation axis, a rotation drive source that rotates the rotating body around the rotation axis, a raw material supply unit that supplies the plasma raw material to the rotating body, and a debris reflection surface that is located in the normal direction of the irradiation position where the energy beam is irradiated and reflects debris incident from the irradiation position in a direction different from the incident path of the energy beam to the irradiation position of the energy beam. The beam source makes the energy beam enter the irradiation position.

Advantages of the Invention

[0024] According to the present invention, it is possible to provide a plasma generation mechanism and a light source device capable of suppressing problems caused by debris generated during plasma generation.

Brief Description of the Drawings

[0025]

Figure 1

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Figure 15

Embodiments for Carrying Out the Invention

[0026] A light source device according to an embodiment of the present invention will be described.

[0027] [Basic Configuration of Light Source Device] FIG. 1 is a schematic diagram showing a configuration example of a light source device 100 according to the present embodiment. The light source device 100 is a light source device of the LPP (Laser Produced Plasma) method. That is, as shown in FIG. 1, the light source device 100 irradiates a plasma raw material 101 with an energy beam EB to excite the plasma raw material 101 to generate a plasma P, and extracts radiation R emitted from the plasma P and uses it as a light source. The radiation R is EUV (Extreme Ultraviolet) light, X-rays, or other electromagnetic waves.

[0028] The plasma raw material 101 is an alloy containing tin (Sn), lithium (Li), gadolinium (Gd), terbium (Tb), gallium (Ga), bismuth (Bi), indium (In), or at least one of these materials, and is in a liquid state. When EUV light is emitted as the radiation R, molten Sn or Li is used as the plasma raw material 101. When X-rays are emitted as the radiation R, molten Ga, Ga alloy, Sn compound, etc. are used as the plasma raw material 101.

[0029] FIG. 1 is a view seen from directly above, showing a schematic cross-section when the light source device 100 is cut horizontally along a position at a predetermined height from the installation surface. In FIG. 1, for the sake of easy understanding of the configuration and operation of the light source device 100, the illustration of the cross-section is omitted for parts where the explanation of the cross-section configuration is not necessary. Hereinafter, the X direction is the left-right direction in the horizontal direction (the positive side of the X-axis is the right side, and the negative side is the left side), the Y direction is the front-rear direction in the horizontal direction (the positive side of the Y-axis is the front side, and the negative side is the rear side), and the Z direction is the vertical direction (the positive side of the Z-axis is the upper side, and the negative side is the lower side). Of course, regarding the application of the present technology, the orientation in which the light source device 100 is used is not limited.

[0030] As shown in FIG. 1, the light source device 100 includes a housing 102, a vacuum chamber 103, an energy beam incident chamber 104, a radiation emission chamber 105, a plasma generation mechanism 106, a control unit 107, and a beam source 108.

[0031] In the example shown in FIG. 1, the housing 102 has an emission hole 102a, an incident hole 102b, and a through hole 102c. In the present embodiment, the emission axis EA of the radiation R is set so as to pass through the emission hole 102a. The radiation R is taken out along the emission axis EA and emitted from the emission hole 102a. Also in the present embodiment, the incident axis IA of the energy beam EB is set so as to pass through the incident hole 102b.

[0032] As shown in FIG. 1, a beam source 108 that emits an energy beam EB is installed outside the housing 102. The beam source 108 is installed such that the energy beam EB enters the inside of the housing 102 along the incident axis IA. As the energy beam EB, an electron beam or a laser beam can be used.

[0033] The light source device 100 is provided with a chamber section C including a plurality of chambers. Specifically, the chamber section C includes a vacuum chamber 103, an energy beam incident chamber (hereinafter simply referred to as the incident chamber) 104, and a radiation emission chamber (hereinafter simply referred to as the emission chamber) 105. The vacuum chamber 103 and the incident chamber 104 are connected to each other, and the vacuum chamber 103 and the emission chamber 105 are connected to each other.

[0034] The incident chamber 104 is configured to be located on the incident axis IA of the energy beam EB, and the emission chamber 105 is configured to be located on the emission axis EA of the radiation R. A collector (condensing lens) 112 for guiding the radiation R is disposed in the emission chamber 105. Further, a plasma generation mechanism 106 for generating a plasma P is disposed in the vacuum chamber 103.

[0035] A utilization device such as a mask inspection device is connected to the end of the emission chamber 105 on the side opposite to the plasma generation mechanism 106. In the example shown in FIG. 1, an application chamber 110, which is a part of the utilization device, is connected. The pressure inside the application chamber 110 may be atmospheric pressure. Further, the inside of the application chamber 110 may be purged by introducing a gas (for example, an inert gas) from a gas injection passage as necessary. Also, the gas inside the application chamber 110 may be exhausted by an exhaust means (not shown). A filter film 111 that physically separates the region where the plasma P is generated from the application chamber 110 is provided between the application chamber 110 and the emission chamber 105.

[0036] The chamber body 109 is provided with an incident window 114. The incident window 114 is arranged at a position aligned with the incident hole 102b on the incident axis IA of the energy beam EB. Further, an exhaust pump 117 is connected to the chamber body 109.

[0037] Also, as shown in FIG. 1, the emission chamber 105 and the incident chamber 104 are respectively provided with gas injection paths 116a and 116b, and gas is supplied from a gas supply device (not shown) into the emission chamber 105 and the incident chamber 104. A gas with a high transmittance to radiation R such as argon or helium is supplied to the emission chamber 105. Also, a gas with a high transmittance to the energy beam EB such as argon or helium is supplied to the incident chamber 104.

[0038] The plasma generation mechanism 106 is a mechanism for generating plasma P in the vacuum chamber 103 and emitting radiation R (X-rays or EUV light). The plasma generation mechanism 106 includes a rotating body 120 as shown in FIG. 1, and the energy beam EB is incident on the rotating body 120. The rotating body 120 is arranged in the vacuum chamber 103 such that the irradiation position I of the energy beam EB is at the intersection of the incident axis IA and the emission axis EA. Details of the plasma generation mechanism 106 will be described later.

[0039] The control unit 107 controls the operations of the respective components of the light source device 100. For example, the control unit 107 controls the operations of the beam source 108 and the exhaust pump 117. The control unit 107 has hardware circuits necessary for a computer such as a CPU and a memory (RAM, ROM). By loading the control program stored in the memory into the RAM and executing it by the CPU, various processes are executed. As the control unit 107, a device such as a PLD (Programmable Logic Device) may be used. In FIG. 1, the control unit 107 is schematically illustrated as a functional block, but the position where the control unit 107 is configured and the like may be arbitrarily designed.

[0040] Also, as shown in FIG. 1, in the present embodiment, a radiation diagnostic unit 119 is connected to the chamber body 109. The radiation diagnostic unit 119 is disposed at a position where radiation R radiated in a direction different from the emission axis EA of the radiation R is incident, and measures the state of the radiation R from the plasma P.

[0041] [Configuration of Plasma Generation Mechanism] As described above, the plasma generation mechanism 106 is a mechanism for generating a plasma P in the vacuum chamber 103 and emitting radiation R (X-rays or EUV light). FIG. 2 is a schematic diagram of the plasma generation mechanism 106. As shown in the figure, the plasma generation mechanism 106 includes a rotating body 120, a rotation drive source 131, a shaft portion 132, a storage tank 133, and a film thickness adjustment mechanism 134.

[0042] The rotation drive source 131 is disposed outside the vacuum chamber 103 and generates the rotational power of the rotating body 120. The rotation drive source 131 is, for example, a motor. The shaft portion 132 penetrates the chamber body 109 and the housing 102 to connect the rotation drive source 131 and the rotating body 120, and transmits the rotational power generated by the rotation drive source 131 to the rotating body 120. The storage tank 133 is disposed vertically below the rotating body 120 and stores the plasma raw material 101.

[0043] The rotating body 120 is disposed in the vacuum chamber 103 and is connected to the shaft portion 132. The rotating body 120 rotates as shown by the arrow S in FIG. 2 due to the rotation of the shaft portion 132. Hereinafter, the rotation axis of the rotating body 120 and the shaft portion 132 is defined as the rotation axis M.

[0044] As shown in FIG. 2, the rotating body 120 has a disk shape. Hereinafter, the surface of the rotating body 120 on the side opposite to the shaft portion 132 is defined as the rotation surface 120a. The rotation axis M is, for example, parallel to the horizontal direction (X - Y direction), and the rotation surface 120a is disposed so as to be parallel to the vertical direction. A part of the rotation surface 120a is immersed in the plasma raw material 101 stored in the storage tank 133, and the plasma raw material 101 adheres thereto as it rotates. The plasma raw material 101 adhering to the rotation surface 120a is transported to the irradiation position I as the rotating body 120 rotates, and is turned into plasma by the energy beam EB irradiated at the irradiation position I.

[0045] As shown in FIG. 2, the film thickness adjusting mechanism 134 is disposed on the rotating body 120 to adjust the film thickness of the plasma raw material 101 adhering to the rotating surface 120a. The film thickness adjusting mechanism 134 is, for example, a structure having a channel structure, and is disposed with a predetermined gap so as to sandwich the rotating body 120 inside thereof, and adjusts the film thickness of the plasma raw material 101 by scraping off the plasma raw material 101 that has not flowed into the gap. The film thickness adjusting mechanism 134 is provided on the upstream side of the irradiation position I in the rotation direction of the rotating body 120, and defines the film thickness of the plasma raw material 101 at the irradiation position I.

[0046] In the plasma generation mechanism 106, as described above, the plasma raw material 101 stored in the storage tank 133 adheres to the rotating surface 120a of the rotating body 120 and is transported to the irradiation position I by the rotation of the rotating body 120. Therefore, the storage tank 133 functions as a "raw material supply unit" that supplies the plasma raw material 101 to the rotating surface 120a.

[0047] [Configuration of the Rotating Body Unit] The plasma generation mechanism 106 includes a rotating body unit that houses the rotating body 120. FIG. 3 is a perspective view of the rotating body unit 150. As shown in the figure, the rotating body unit 150 includes a rotating body 120 and a cover 160, and the rotating body 120 is housed inside the cover 160. Note that the illustration of the cover 160 is omitted in FIGS. 1 and 2. FIG. 4 is a cross-sectional view of the rotating body unit 150, which is a cross-sectional view taken along line A1-A1 (X-Y plane) of FIG. 3.

[0048] The cover 160 surrounds the rotating body 120 to prevent the scattering of debris and forms the storage tank 133. The cover 160 is composed of a first cover member 161 and a second cover member 162. As shown in FIG. 3, the rotating body 120 is housed inside the cover 160. In addition, the plasma raw material 101 is stored in the vertically lower portion of the cover 160, and the vertically lower portion of the cover 160 constitutes the storage tank 133. A heating mechanism (not shown) is provided around the storage tank 133 to heat and melt the plasma raw material 101 stored in the storage tank 133.

[0049] As shown in FIG. 4, the first cover member 161 has a bottom portion 161a and a side wall portion 161b. The bottom portion 161a has a disk shape, and a through hole 161c is provided at the center as shown in FIG. 4. The through hole 161c is a hole through which the shaft portion 132 is inserted. The side wall portion 161b has a cylindrical shape and is continuous with the peripheral edge of the bottom portion 161a.

[0050] As shown in FIG. 4, the second cover member 162 is joined to the side wall portion 161b of the first cover member 161. As shown in the same figure, the second cover member 162 has a flat plate portion 163 and a debris reflection structure 164. The flat plate portion 163 has a flat plate shape and faces the rotating surface 120a of the rotating body 120 as shown in FIG. 4. As shown in FIG. 4, the surface of the flat plate portion 163 facing the rotating surface 120a is defined as the facing surface 163a. The facing surface 163a is a surface parallel to the rotating surface 120a, for example, a surface parallel to the vertical direction.

[0051] As shown in FIG. 4, an opening 166 is provided in the flat plate portion 163. The opening 166 is provided through the second cover member 162 and is an opening through which the energy beam EB and the radiation R pass.

[0052] The debris reflection structure 164 faces the irradiation position I and reflects the debris generated during plasma generation. As shown in FIG. 4, the debris reflection structure 164 is provided at a position on the facing surface 163a that faces the irradiation position I, specifically, adjacent to the opening 166.

[0053] The debris reflection structure 164 has a debris reflection surface 164a. The debris reflection surface 164a is the surface of the debris reflection structure 164 on the side of the rotating body 120 and is a surface that reflects the debris incident from the irradiation position I. As shown in FIG. 4, the debris reflection surface 164a is located in the normal direction H1 of the irradiation position I, and reflects the debris incident from the irradiation position I in a direction different from the incident path of the energy beam EB to the irradiation position I and the emission path of the radiation R from the irradiation position I. Specifically, the debris reflection surface 164a reflects the debris in a direction different from the opening 166.

[0054] At least a part of the debris reflecting surface 164a is a surface that is neither perpendicular to the normal direction H1 nor parallel to the normal direction H1. As shown in FIG. 4, the normal direction of the debris reflecting surface 164a is defined as the normal direction H2. As shown in the same figure, the debris reflecting surface 164a is a plane inclined with respect to the opposing surface 163a, and is a surface where the normal direction H2 at each position is parallel.

[0055] [Operation and Effect of Light Source Device] The operation and effect of the light source device 100 will be described. The energy beam EB plasmaizes the plasma raw material 101 at the irradiation position I, and generates a plasma P as shown in FIG. 4. Radiation R (see FIG. 1) is emitted from the plasma P and is emitted through the aperture 166. Along with this plasmaization, as shown in FIG. 4, debris D, which is the vapor and smoke of the plasma raw material 101, jets out from the irradiation position I. The debris D jets out mainly along the normal direction H1 (Y direction) of the rotating surface 120a.

[0056] Here, in the rotating unit 150, the debris reflecting surface 164a is located in the normal direction H1 of the irradiation position I. Therefore, the debris D ejected from the irradiation position I collides with the debris reflecting surface 164a and is reflected by the debris reflecting surface 164a. If the direction in which the debris D is reflected by the debris reflecting surface 164a is defined as the reflection direction T, the reflection direction T is a direction toward the inside of the cover 160 and is different from the direction of the aperture 166. Specifically, the reflection direction can be controlled by the normal direction H2 (see FIG. 4) of the debris reflecting surface 164a.

[0057] FIG. 5 is a schematic diagram showing the operation of the light source device 100 when the debris reflection structure 164 is not provided. As shown in the figure, when the debris D jets out from the irradiation position I, the debris D collides with the opposing surface 163a, and debris D' containing various small particles is generated. The debris D' diffuses within the cover 160, and a part of it adheres to the aperture 166. The debris D' adhering to the aperture 166 narrows the aperture 166 and shields or attenuates the energy beam EB and the radiation R passing through the aperture 166, resulting in a decrease in the output of the radiation R.

[0058] Also, when debris D' floats near the opening 166, the radiation R is absorbed by the debris D', and the output of the radiation R also decreases at this point. In addition, when the debris D' is released from the opening 166, it adheres to the members inside the vacuum chamber 103 (see FIG. 1), causing problems such as unnecessary conduction.

[0059] On the other hand, when the debris reflecting surface 164a is provided as shown in FIG. 4, the debris D is reflected by the debris reflecting surface 164a in a reflection direction T different from the opening 166, so that the adhesion of the debris D to the opening 166 is prevented. Thereby, the shielding and attenuation of the energy beam EB and the radiation R can be prevented, and the output decrease of the radiation R caused by the debris D can be prevented. In addition, since the release of the debris D from the opening 166 is also suppressed, it is also possible to prevent problems with external members.

[0060] [Regarding the entrance and exit openings] As described above, the debris reflecting surface 164a reflects the debris incident from the irradiation position I in a direction different from the opening 166. Here, the opening 166 may include an entrance and an exit. The entrance 167 is provided in the flat plate portion 163 and is an opening through which the energy beam EB passes. The exit 168 is provided in the flat plate portion 163 and is an opening through which the radiation R passes. In this case, the debris reflecting surface 164a is configured such that the component H3 faces a direction different from the entrance 167 and the exit 168. Also in this case, the adhesion of the debris D to the entrance 167 and the exit 168 and the release of the debris D from the entrance 167 and the exit 168 can be suppressed. Also, the debris reflecting surface 164a may be configured such that the component H3 faces the direction of the exit 168. Also in this case, the debris D reflected by the debris reflecting surface 164a scatters at a shallower angle with respect to the exit 168 than when the debris reflecting structure 164 is not provided (see FIG. 5), so that the adhesion of the debris D to the entrance 167 and the exit 168 and the release of the debris D from the entrance 167 and the exit 168 can be suppressed.

[0061] [Regarding the angle of the debris reflecting surface] The angle of the debris reflecting surface 164a will be described. FIG. 6 is a schematic diagram showing the incident angle and the reflection angle of the debris D incident on the debris reflecting surface 164a. As shown in the figure, the angle with respect to the normal direction H2 of the debris D incident on the debris reflecting surface 164a is defined as the incident angle θ1, and the angle with respect to the normal direction H2 of the debris D reflected by the debris reflecting surface 164a is defined as the reflection angle θ2.

[0062] Here, the angle of the debris reflecting surface 164a and the reflection angle of the debris D were examined by simulation. Using the two-body collision simulation software TRIM (TRanspotation of Ion in Material), the recoil direction of the ion N corresponding to the incident energy and the collision angle with respect to the collision surface G was obtained by Monte Carlo calculation using the two-body collision approximation, as shown in FIG. 6. The normal direction of the collision surface G is defined as the normal direction K, the angle with respect to the normal direction K of the ion N colliding with the collision surface G is defined as the collision angle φ1, and the angle with respect to the normal direction K of the ion N recoiling from the collision surface G is defined as the recoil angle φ2. In this simulation, attention is paid to the behavior of the ion N projected onto the X-Y plane.

[0063] For example, when the collision angle φ1 is 45° and the recoil angle φ2 is -45°, the ion N will return to the injection point. Since the ease of recoil of the ion N changes depending on the incident energy and the collision angle of the ion N, the calculation was carried out until the number of recoiled ions N became a sufficient number of samples for investigating the angular distribution. For example, when the incident energy is 5 keV and the collision angle φ1 is 45°, 6 million sample ions were collided with the collision surface G, and the recoil angle φ2 was evaluated.

[0064] In calculation, the traveling direction of the ion may be slightly changed between the ion injection point and the collision surface G. Therefore, the collision angle φ1 does not become exactly the specified value. However, since it is considered that debris is generated with a certain degree of spread even in an actual light source device, there is no practical problem.

[0065] FIG. 7 is a graph showing the distribution of recoiled ions at each incident energy when the collision angle φ1 is 45°. FIG. 8 is a graph showing the distribution of recoiled ions at each incident energy when the collision angle φ1 is 60°.

[0066] As shown in these figures, when the incident energy is 1 keV, the recoil angle φ2 has a peak at about 30° to 40°. The incident energy of 1 eV is the lowest energy among the conditions examined. The higher the energy of the debris, the greater the damage to the condenser etc. during the collision. However, the ratio of low-energy debris in the total number of debris is considered to be larger than that of other energies for which the simulation was performed. Since the recoil angle φ2 has a peak at about 30° to 40°, when the incident energy is 1 keV, it can be said that the total number of debris D incident on the irradiation position I among the debris D reflected by the debris reflection surface 164a is clearly less than the total number of debris D incident on other positions. When the incident energy is 100 keV, in any of the calculation results, the recoil angle φ2 has a peak at about 30° to 40°.

[0067] From FIGS. 7 and 8, it can be seen that as the collision angle φ1 increases, the recoil angle φ2 converges around a certain angle. Also, in this model, since the angle of the collision surface G becomes steeper, the normal direction K moves away from the incident direction of the ion N, and it is shown that the reflection angle θ2 of the debris D can be controlled by changing the angle of the debris reflection surface 164a with respect to the direction in which the debris D is incident.

[0068] FIG. 9 is a graph plotting the average recoil angle against the collision angle φ1. The average recoil angle is the average value of the recoil angle φ2. As shown in the figure, it can be seen that regardless of the ion energy, the recoil angle φ2 [degrees] is 40Ln(0.018φ1) with respect to the collision angle φ1 [degrees]. However, the peak near 90° of the recoil angle φ2 when the incident energy is 1 keV and the collision angle φ1 is 75° is excluded from this calculation.

[0069] As described above, the recoil angle φ2 and the total number of reflected ions N depend on the incident energy and the collision angle φ1 of the ions N. Also, as the collision angle φ1 increases, ions N tend to recoil more easily. Therefore, it can be said that it is effective to provide the debris reflecting surface 164a in order not to return the debris D to the irradiation position I as much as possible. Note that the variation in the recoil angle φ2 was about σ = 15 to 35°. Multiple factors are considered for this variation. For example, it is considered that the calculated collision angle φ1 does not strictly become the specified value. Considering the variations in the collision angle φ1 and the recoil angle φ2, it is preferable to have means for restricting the destination of the debris D reflected by the debris reflecting surface 164a as described later.

[0070] [Regarding various configurations of the debris reflecting structure] As described above, the debris reflecting structure 164 only needs to be such that the debris reflecting surface 164a reflects the debris incident from the irradiation position I in a direction different from the incident path to the irradiation position I of the energy beam EB, and can have various configurations. FIGS. 10 to 12 are schematic views of the debris reflecting structure 164 having various configurations.

[0071] As shown in FIG. 10, the debris reflecting surface 164a may have a flat surface 171 and a curved concave portion 172. As described above, the normal direction H2 of the debris reflecting surface 164a is a direction in which the component H3 (see FIG. 4) parallel to the rotating surface 120a (Z-X plane) faces a direction different from the opening 166.

[0072] FIG. 11 is a schematic view showing the reflection of the debris D by this debris reflecting surface 164a. As shown in the figure, by making the debris reflecting surface 164a curved, the debris D can be reflected in a concentrated manner in one direction. When the irradiation position I and the debris reflecting surface 164a are close, only a part may be made curved in this way.

[0073] Also, the debris reflecting surface 164a may have a shape with a flat surface and a hemispherical concave portion. In this case, the debris D can be reflected in a form that converges it to a single point. Also, the debris reflecting surface 164a may be configured by combining a plurality of small curved surfaces. In this case, although the debris D cannot be converged in one direction, it is possible to suppress the divergence of the debris D. Further, the debris reflecting surface 164a can also be made into a stepped shape configured by combining a plurality of small flat surfaces.

[0074] Furthermore, as shown in FIG. 12, the debris reflecting surface 164a may have a C-shaped configuration when viewed from the normal direction H1 (Y direction). As shown in FIG. 12, it is preferable that the component H3 at each position is inside the C-shaped configuration and faces a direction different from the opening 166. Also, the debris reflecting surface 164a may have a flat surface and a curved concave portion.

[0075] Furthermore, the debris reflecting surface 164a may have a C-shaped configuration when viewed from the normal direction H1 (Y direction), and the component H3 at each position may be outside the C-shaped configuration and face a direction different from the opening 166. Also, a plurality of debris reflecting structures 164 may be provided, and there may also be a plurality of debris reflecting surfaces 164a. Also in this case, the component H3 at each position can be made to face a direction different from the opening 166.

[0076] The support structure of the debris reflecting structure 164 is not limited to being disposed on the flat plate portion 163 of the cover 160 as described above. FIG. 13 is a schematic diagram showing the support structure of the debris reflecting structure 164. As shown in the figure, the flat plate portion 163 is provided with an opening 169 at a position facing the irradiation position I. The debris reflecting structure 164 is supported by a support member 181 different from the cover 160, and the debris reflecting surface 164a faces the irradiation position I through the opening 169. The support member 181 is not particularly limited, but for example, it can be a cantilever structure that connects an external member such as the chamber body 109 (see FIG. 1) and the debris reflecting structure 164. The support member 181 can approach and separate from the rotating body 120 as shown by the arrow in the figure, and the distance between the debris reflecting surface 164a and the rotating surface 120a can be adjusted.

[0077] Also, the debris reflecting structure 164 may be rotatable. FIG. 14 is a cross-sectional view of a rotating body unit 150 including a rotatable debris reflecting structure 164. As shown in the figure, the debris reflecting structure 164 includes a rotation axis 164b and is configured to be rotatable around the rotation axis 164b. The rotation axis 164b is an axis extending in a direction (X direction) perpendicular to the normal direction H1 (see FIG. 4). The debris reflecting surface 164a is the surface around the rotation axis 164b of the debris reflecting structure 164, and a part thereof faces the irradiation position I through the opening 169. When the debris reflecting structure 164 rotates, the portion of the debris reflecting surface 164a facing the irradiation position I is replaced with the rotation.

[0078] When the debris D is incident on the debris reflecting surface 164a, the debris reflecting surface 164a is heated by the kinetic energy of the debris D. Here, by rotating the debris reflecting structure 164, the debris reflecting surface 164a facing the irradiation position I can be replaced, and the long life of the debris reflecting structure 164 can be achieved.

[0079] Also, in the rotatable debris reflecting structure 164, the debris reflecting surface 164a can also be formed into a curved surface. In addition, the debris reflecting structure 164 can be rotatable, and the debris reflecting surface 164a can have various shapes as described above.

[0080] It is also possible to use a rotary vane trap to rotate the debris reflecting structure 164. FIG. 15 is a cross-sectional view of a rotating unit 150 including a rotary vane trap 190. As shown in the figure, the rotary vane trap 190 includes a central support column 191, vanes 192, and an outer peripheral ring 193.

[0081] The central support column 191 is connected to a rotation drive source (not shown) and rotates around the rotation axis F. The vanes 192 are connected to the central support column 191, are plate-shaped in the traveling direction of the radiation R emitted from the irradiation position I, and a plurality of them are provided radially when viewed from the direction of the rotation axis F. The outer peripheral ring 193 is an annular member centered on the rotation axis F and surrounds the periphery of the vanes 192. In the rotary vane trap 190, as the vanes 192 rotate around the rotation axis F, the debris that has passed through the opening 166 collides with the vanes 192 and is captured by the vanes 192.

[0082] The debris reflecting structure 164 is connected to the rotary vane trap 190 and rotates as the rotary vane trap 190 rotates. Specifically, the debris reflecting structure 164 is disposed on the rotation axis F and is supported by a support member 194 fixed to the central support column 191. When the central support column 191 rotates, it rotates around the rotation axis F. The shape of the debris reflecting structure 164 is, for example, a conical shape centered on the rotation axis F. With this structure, it becomes possible to rotate the debris reflecting structure 164 by the rotation drive source for the rotary vane trap 190, and there is no need to separately provide a rotation drive source for the debris reflecting structure 164.

[0083] Furthermore, in a configuration where the debris reflection structure 164 is rotated by utilizing the rotation of the rotary foil trap 190, the debris reflection structure 164 may be supported by a support member, and the support member may be connected to the central support column 191 by a rotation transmission mechanism. The rotation transmission mechanism is a mechanism that transmits the rotation of the central support column 191 to the support member and is composed of gears or the like.

[0084] Accordingly, when the central support column 191 rotates around the rotation axis, the rotation is transmitted to the support member by the rotation transmission mechanism, and the support member and the debris reflection structure 164 rotate around the rotation axis. By using the rotation transmission mechanism, even if the debris reflection structure 164 is disposed at a distance from the rotation axis of the rotary foil trap 190, it becomes possible to rotate the debris reflection structure 164 by a rotation drive source for the rotary foil trap 190. The shape of the debris reflection structure 164 is, for example, a conical shape centered on the rotation axis.

[0085] The rotary foil trap 190 and the configuration for rotating the debris reflection structure 164 by its rotation are not limited to those described above, and any configuration may be used as long as it can rotate the debris reflection structure 164 by the rotation of the rotary foil trap 190.

[0086] [Regarding the present disclosure] Among the characteristic portions of the present technology described above, it is also possible to combine at least two characteristic portions. Also, the various effects described above are merely examples and are not limiting, and other effects may be exhibited.

Explanation of reference numerals

[0087] 100... Light source device 101... Plasma raw material 106... Plasma generation mechanism 108... Beam source 120... Rotating body 131... Rotation drive source 132... Shaft portion 133... Storage tank 134... Film thickness adjustment mechanism 150…Rotating body unit 160…Cover 161…First cover member 162…Second cover member 164…Debris reflection structure 164a…Debris reflection surface 164b…Rotation axis 166…Opening 167…Inlet 168…Outlet 169…Opening 190…Rotary foil trap

Claims

1. A plasma generation mechanism included in a light source device that converts a liquid plasma raw material into plasma by irradiating an energy beam and extracts radiation, a rotating body having a rotating surface that is a surface rotating around a rotation axis, a rotation drive source that rotates the rotating body around the rotation axis, a raw material supply unit that supplies the plasma raw material to the rotating body, and a debris reflection surface that is located in the normal direction of the irradiation position where the energy beam is irradiated and reflects debris incident from the irradiation position in a direction different from the incident path of the energy beam to the irradiation position. A plasma generation mechanism comprising the above.

2. The plasma generation mechanism according to Claim 1, wherein the irradiation position is located on the rotating surface A plasma generation mechanism.

3. The plasma generation mechanism according to Claim 1, wherein the debris reflection surface reflects debris incident from the irradiation position in a direction different from the incident path of the energy beam to the irradiation position and the emission path of the radiation from the irradiation position. A plasma generation mechanism.

4. The plasma generation mechanism according to Claim 1, wherein the raw material supply unit has a storage tank for storing the plasma raw material, and a part of the rotating surface of the rotating body is immersed in the plasma raw material stored in the storage tank. A plasma generation mechanism.

5. The plasma generation mechanism according to Claim 4, further comprising a cover that forms the storage tank and surrounds the rotating body, wherein the normal direction at each position on the debris reflection surface faces inward of the cover. A plasma generation mechanism.

6. The plasma generation mechanism according to Claim 5, wherein the cover has an opening through which the energy beam passes, and the debris reflection surface reflects debris incident from the irradiation position in a direction different from the opening. A plasma generation mechanism.

7. The plasma generation mechanism according to Claim 6, wherein the opening includes an incident port through which the energy beam passes and an emission port through which the radiation passes, and the debris reflection surface faces the irradiation position through the opening. A plasma generation mechanism

8. The plasma generation mechanism according to Claim 5, wherein the cover has a facing surface facing the rotating surface, and the debris reflection surface is the surface of a debris reflection structure provided at a position on the facing surface that faces the irradiation position. A plasma generation mechanism

9. The plasma generation mechanism according to Claim 7, The debris reflecting surface is the surface of a debris reflecting structure supported by a support member different from the cover. Plasma generation mechanism

10. The plasma generation mechanism according to claim 1, wherein at least a part of the debris reflecting surface is curved. Plasma generation mechanism.

11. The plasma generation mechanism according to claim 1, wherein the debris reflecting surface is the surface of a rotating debris reflecting structure. Plasma generation mechanism.

12. The plasma generation mechanism according to claim 1, wherein the radiation is extreme ultraviolet light or X-rays. Plasma generation mechanism.

13. The plasma generation mechanism according to claim 1, wherein the plasma raw material is an alloy containing tin, lithium, gadolinium, terbium, gallium, bismuth, indium, or at least one of these materials. Plasma generation mechanism.

14. A light source device that converts a liquid plasma raw material into plasma by irradiating it with an energy beam and extracts radiation, comprising a rotating body having a rotating surface that is a surface rotating around a rotation axis, a rotation drive source that rotates the rotating body around the rotation axis, a raw material supply unit that supplies the plasma raw material to the rotating body, and a debris reflecting surface that is located in the normal direction of the irradiation position where the energy beam is irradiated and reflects debris incident from the irradiation position in a direction different from the incident path of the energy beam to the irradiation position, a beam source that makes the energy beam incident on the irradiation position, and a light source device.

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