Plasma generation mechanism and light source device

Abstract

Provided are: a plasma generation mechanism for which the cost of supplying a plasma raw material is low, and which is highly durable; and a light source device.　A plasma generation mechanism according to one embodiment of the present invention is provided with a rotor, a rotary drive source, a storage chamber, a heating unit, and a raw material supply unit. The rotor rotates around a rotating shaft. The rotary drive source causes the rotor to turn around the rotating shaft. The storage chamber stores a liquid plasma raw material, and a part of the rotor is immersed in the stored liquid plasma raw material. The heating unit heats the liquid plasma raw material stored in the storage chamber. The raw material supply unit comprises: a raw material introduction path through which a solid plasma raw material that is the plasma raw material in a solid state passes; and a raw material supply port which is provided to the raw material introduction path, and through which the solid plasma raw material cannot pass but a liquid plasma raw material, resulting from the melting of the solid plasma raw material, can pass. The liquid plasma raw material that has passed through the raw material supply port flows into the storage chamber.

Description

Plasma generation mechanism and light source device

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

[0002] Traditionally, X-rays have been used for medical, industrial, and research applications. In the medical field, X-rays are used for applications such as chest radiography, dental radiography, and CT (Computer Tomography). In the industrial field, X-rays are used for applications such as non-destructive testing and tomographic non-destructive testing to observe the interior of materials such as structures and welds. In the research field, X-rays are used for applications such as X-ray diffraction to analyze the crystalline structure of materials and X-ray spectroscopy (X-ray fluorescence analysis) to analyze the constituent elements of materials. Extreme ultraviolet light (hereinafter also referred to as "EUV (Extreme Ultra Violet) light") with a wavelength of 13.5 nm, which is in the soft X-ray region with a relatively long wavelength among X-rays, has recently been used as exposure light.

[0003] Some EUV light source devices generate EUV light by irradiating a plasma raw material, such as molten tin or lithium, with an energy beam to excite it, thereby generating high-temperature plasma, from which EUV light is extracted. Methods that use laser light as the energy beam are called LPP (Laser Produced Plasma), and methods that use electrical discharge are called DPP (Discharge Produced Plasma) or LDP (Laser Assisted Discharge Produced Plasma).

[0004] Known LPP-type EUV light source devices generate plasma by exciting plasma raw material droplets by focusing laser light on the droplets. In contrast, a method has recently been developed for supplying plasma raw material to a laser light irradiation area using the centrifugal force of a rotor (see, for example, Patent Document 1). In this method, the rotor rotates with its lower portion immersed in the stored plasma raw material, causing the plasma raw material to adhere to the rotor surface, supplying the plasma raw material to the irradiation area on the rotor surface. This method does not require the plasma raw material to be supplied as droplets, and therefore can produce high-intensity radiation with a relatively simple configuration compared to methods that focus laser light on droplets.

[0005] JP 2014-216286 A

[0006] In EUV light source devices such as those described in Patent Document 1, the method of supplying plasma raw material to the storage tank poses a problem. In a method of circulating a large amount of plasma raw material between the storage tank and the raw material supply mechanism, as in Patent Document 1, a large amount of energy is required to melt the plasma raw material. In addition, the path along which the molten plasma raw material circulates must be made of a material or coating that is corrosion-resistant to the plasma raw material, which increases costs.

[0007] On the other hand, if the plasma raw material is not circulated and only plasma raw material stored in a storage tank is used, the large amount of energy described above is unnecessary, but the need to replenish the plasma raw material remains. Furthermore, the supply path for the plasma raw material must be at or above the melting point, and the supply path must be made of a material or coating that is corrosion-resistant to the plasma raw material. Furthermore, the supply path must use expensive heat-resistant valves, and even if they are heat-resistant, their lifespan will inevitably be shortened.

[0008] In view of the above circumstances, an object of the present invention is to provide a plasma generating mechanism and a light source device that are low cost and highly durable in terms of supplying plasma raw material.

[0009] In order to achieve the above object, one aspect of the present invention provides a plasma generation mechanism included in a light source device that converts a liquid plasma raw material, which is a molten plasma raw material, into plasma by irradiating it with an energy beam and extracts radiation, and the plasma generation mechanism includes a rotor, a rotary drive source, a reservoir, a heating unit, and a raw material supply unit. The rotor rotates about a rotation axis. The rotary drive source rotates the rotor about the rotation axis. The reservoir tank stores the liquid plasma raw material, and a portion of the rotor is immersed in the stored liquid plasma raw material. The heating unit heats the liquid plasma raw material stored in the reservoir. The raw material supply unit has a raw material inlet path through which a solid plasma raw material, which is a solid plasma raw material, passes, and a raw material supply port provided in the raw material inlet path, through which the solid plasma raw material cannot pass but which the liquid plasma raw material formed by melting the solid plasma raw material can pass, and the liquid plasma raw material that passes through the raw material supply port flows into the reservoir.

[0010] With this configuration, when solid plasma raw material is introduced into the raw material inlet of the raw material supply unit, the solid plasma raw material cannot pass through the raw material supply port, and only the liquid plasma raw material generated by melting passes through the raw material supply port and flows into the storage tank. Supplying liquid plasma raw material to the plasma generation mechanism requires a large amount of energy to maintain the molten state of the plasma raw material. However, by supplying solid plasma raw material and melting it only when it is supplied to the storage tank, the required energy can be reduced. Furthermore, some molten metals are corrosive, requiring the use of corrosion-resistant coatings or materials. However, this reduces the number of locations where such coatings or materials are used, thereby reducing costs. Furthermore, no valves are required to control the liquid plasma raw material, achieving high durability.

[0011] The raw material supply port may be configured so that the solid plasma raw material does not come into contact with the liquid surface of the liquid plasma raw material stored in the storage tank, or so that only the lower end of the solid plasma raw material comes into contact with the liquid surface.

[0012] The maximum width of the raw material supply port may be smaller than the minimum width of the solid plasma raw material.

[0013] The heating section may further heat and melt the solid plasma raw material located in the raw material introduction path.

[0014] The raw material supply unit may include an outer peripheral member that forms the outer periphery of the cylindrical raw material inlet channel, and a stopper that is provided at the end of the raw material inlet channel on the storage tank side and that keeps the solid plasma raw material inside the raw material inlet channel.

[0015] The heating section may further heat and melt the solid plasma raw material held by the stopper.

[0016] The rotating body may have a rotation surface on which the energy beam is incident.

[0017] The raw material supply unit may be provided on a rear side of the rotation surface of a cover member that houses the rotor and forms the storage tank.

[0018] The radiation may be extreme ultraviolet light or x-rays.

[0019] The plasma raw material may be tin, lithium, gadolinium, terbium, gallium, bismuth, indium, or an alloy containing at least one of these materials.

[0020] To achieve the above object, one embodiment of the present invention provides a light source device that converts a liquid plasma raw material (a molten plasma raw material) into plasma by irradiating it with an energy beam to produce radiation, and includes a plasma generation mechanism and a beam source. The plasma generation mechanism includes a rotor that rotates about an axis of rotation, a rotary drive source that rotates the rotor about the axis of rotation, a reservoir tank that stores the liquid plasma raw material and in which a portion of the rotor is immersed in the stored liquid plasma raw material, a heating unit that heats the liquid plasma raw material stored in the reservoir, a raw material inlet path through which a solid plasma raw material (the solid plasma raw material) passes, and a raw material supply unit that is provided in the raw material inlet path and has a raw material supply port that prevents the solid plasma raw material from passing through but allows the liquid plasma raw material (the solid plasma raw material melted from the solid plasma raw material) to pass through, and through which the liquid plasma raw material that has passed through the raw material supply port flows into the reservoir. The beam source directs the energy beam toward the plane of rotation.

[0021] According to the present invention, it is possible to provide a plasma generating mechanism and a light source device that are low cost and highly durable in relation to the supply of plasma raw material.

[0022] Fig. 1 is a schematic diagram of a light source device according to an embodiment of the present invention. Fig. 2 is a schematic diagram of a plasma generation mechanism provided in the light source device. Fig. 3 is a schematic diagram showing the supply of liquid plasma raw material from the raw material supply unit. Fig. 4 is a cross-sectional view of the rotor unit. Fig. 5 is a cross-sectional view of the rotor unit. Fig. 6 is a schematic diagram showing the configuration of the raw material supply port.

[0023] A light source device according to an embodiment of the present invention will be described.

[0024] [Basic Configuration of Light Source Device] Fig. 1 is a schematic diagram showing an example configuration of a light source device 100 according to this embodiment. The light source device 100 is an LPP (Laser Produced Plasma) type light source device. That is, as shown in Fig. 2, the light source device 100 is a device that irradiates a liquid plasma raw material 101 with an energy beam EB to excite the liquid plasma raw material 101 and generate plasma P, and extracts radiation R emitted from the plasma P to use as a light source. The radiation R is EUV (Extreme Ultraviolet) light, X-rays, or other electromagnetic waves.

[0025] The liquid plasma raw material 101 is a molten metal or alloy, such as liquid-phase tin (Sn), lithium (Li), gadolinium (Gd), terbium (Tb), gallium (Ga), bismuth (Bi), indium (In), or an alloy containing at least one of these materials. When EUV light is emitted as the radiation R, molten Sn or Li is used as the liquid plasma raw material 101. When X-rays are emitted as the radiation R, molten Ga, a Ga alloy, an Sn compound, or the like is used as the liquid plasma raw material 101.

[0026] FIG. 1 is a diagram showing a schematic cross section of the light source device 100 taken along the horizontal direction at a predetermined height from the installation surface, as viewed from vertically above. In FIG. 1 , cross sections not necessary for explaining the cross-sectional configuration are omitted for ease of understanding the configuration and operation of the light source device 100. Hereinafter, the X direction will be described as the left-right direction of 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 will be described as the front-to-rear direction of 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 will be described as the vertical direction (the positive side of the Z axis is the upper side, and the negative side is the lower side). Of course, the application of the present technology is not limited to the orientation in which the light source device 100 is used.

[0027] As shown in FIG. 1, the light source device 100 includes a housing 102, a vacuum chamber 103, an energy beam entrance chamber 104, a radiation exit chamber 105, a plasma generation mechanism 106, a control unit 107, and a beam source 108.

[0028] 1 , the housing 102 has an exit hole 102a, an entrance hole 102b, and a through-hole 102c. In this embodiment, the exit axis EA of the radiation R is set so as to pass through the exit hole 102a. The radiation R is extracted along the exit axis EA and emitted from the exit hole 102a. In this embodiment, the entrance axis IA of the energy beam EB is set so as to pass through the entrance hole 102b.

[0029] 1, a beam source 108 that emits an energy beam EB is installed outside the housing 102. The beam source 108 is installed so that the energy beam EB enters the inside of the housing 102 along an incident axis IA. An electron beam or laser light can be used as the energy beam EB.

[0030] 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 an incident chamber) 104, and a radiation exit chamber (hereinafter simply referred to as an exit chamber) 105. The vacuum chamber 103 and the incident chamber 104 are connected to each other, and the vacuum chamber 103 and the exit chamber 105 are also connected to each other.

[0031] The entrance chamber 104 is configured to be located on an entrance axis IA of the energy beam EB, and the exit chamber 105 is configured to be located on an exit axis EA of the radiation R. A collector (condensing mirror) 112 that guides the radiation R is disposed within the exit chamber 105. Furthermore, a plasma generation mechanism 106 that generates plasma P is disposed within the vacuum chamber 103.

[0032] A utilization device such as a mask inspection device is connected to the end of the extraction chamber 105 opposite the plasma generation mechanism 106. In the example shown in FIG. 1 , an application chamber 110 is connected as a chamber forming part of the utilization device. The pressure inside the application chamber 110 may be atmospheric pressure. Furthermore, the interior of the application chamber 110 may be purged by introducing a gas (e.g., an inert gas) through a gas injection path as needed. Furthermore, the gas inside the application chamber 110 may be exhausted by an exhaust means (not shown). A filter film 111 is provided between the application chamber 110 and the extraction chamber 105 to physically separate the region where the plasma P is generated from the application chamber 110.

[0033] The chamber body 109 is provided with an entrance window 114. The entrance window 114 is arranged at a position aligned with the entrance hole 102b on the entrance axis IA of the energy beam EB. An exhaust pump 117 is also connected to the chamber body 109.

[0034] 1, the extraction chamber 105 and the incidence chamber 104 are provided with gas injection paths 116a and 116b, respectively, and gas is supplied from a gas supply device (not shown) to the extraction chamber 105 and the incidence chamber 104. A gas having a high transmittance to the radiation R, such as argon or helium, is supplied to the extraction chamber 105. A gas having a high transmittance to the energy beam EB, such as argon or helium, is supplied to the incidence chamber 104.

[0035] 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). As shown in FIG. 1 , the plasma generation mechanism 106 includes a rotor 120, onto which an energy beam EB is incident. The rotor 120 is disposed in the vacuum chamber 103 so that an irradiation position I of the energy beam EB is located at the intersection of an entrance axis IA and an exit axis EA. The plasma generation mechanism 106 will be described in detail later.

[0036] The control unit 107 controls the operation of each component of the light source device 100. For example, the control unit 107 controls the operation 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 memory (RAM, ROM). The CPU loads a control program stored in the memory into the RAM and executes it, thereby executing various processes. A device such as a PLD (Programmable Logic Device) may be used as the control unit 107. Although the control unit 107 is schematically illustrated as a functional block in FIG. 1 , the location where the control unit 107 is configured may be designed as desired.

[0037] 1 , in this embodiment, a radiological diagnostic unit 119 is connected to the chamber body 109. The radiological diagnostic unit 119 is disposed at a position where the radiation R emitted in a direction different from the emission axis EA of the radiation R is incident, and measures the state of the radiation R emitted from the plasma P.

[0038] [Configuration of Plasma Generation Mechanism] As described above, 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). Figure 2 is a schematic diagram of the plasma generation mechanism 106. As shown in the figure, the plasma generation mechanism 106 includes a rotor 120, a rotary drive source 131, a shaft 132, and a storage tank 133.

[0039] Rotational drive source 131 is disposed outside vacuum chamber 103 and generates rotational power for rotating body 120. Rotational drive source 131 is, for example, a motor. Shaft 132 passes through chamber main body 109 and housing 102 to connect rotational drive source 131 and rotating body 120 and transmits the rotational power generated by rotational drive source 131 to rotating body 120. Shaft 132 is rotatably supported by mechanical seal 134. Storage tank 133 is disposed vertically below rotating body 120 and stores liquid plasma raw material 101.

[0040] The rotating body 120 is disposed in the vacuum chamber 103 and is connected to the shaft portion 132. The rotating body 120 rotates due to the rotation of the shaft portion 132, as shown by the arrow S1 in Fig. 2. Hereinafter, the rotation axis of the rotating body 120 and the shaft portion 132 will be referred to as the rotation axis M.

[0041] As shown in Figure 2, the rotor 120 has a disk shape. Hereinafter, the surface of the rotor 120 opposite the shaft 132 will be referred to 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 arranged so that it is parallel to the vertical direction. A portion of the rotation surface 120a is immersed in the liquid plasma raw material 101 stored in the storage tank 133, and the liquid plasma raw material 101 adheres to the rotation surface 120a as the rotor 120 rotates. The liquid plasma raw material 101 adhering to the rotation surface 120a is transported to the irradiation position I as indicated by the arrow S2 in the figure as the rotor 120 rotates, and is converted into plasma by the energy beam EB irradiated at the irradiation position I.

[0042] 1, film thickness adjustment mechanisms 135 may be arranged around the rotor 120 with a predetermined gap between them, and adjust the film thickness of the liquid plasma raw material 101 by scraping off any liquid plasma raw material 101 that has not flowed into the gap. The film thickness adjustment mechanism 135 is located upstream of irradiation position I in the direction of rotation of the rotor 120, and determines the film thickness of the liquid plasma raw material 101 at irradiation position I.

[0043] [Configuration of Rotating Body Unit] The plasma generation mechanism 106 includes a rotating body unit that houses the rotating body 120. As shown in Fig. 2, the rotating body unit 150 includes the rotating body 120, a cover member 161, a heating unit 162, and a raw material supply unit 163, and the rotating body 120 is housed in the cover member 161. Note that the cover member 161, the heating unit 162, and the raw material supply unit 163 are not shown in Fig. 1.

[0044] Cover member 161 houses rotor 120 to prevent debris from scattering, and also forms storage tank 133. Liquid plasma raw material 101 is stored in the vertically lower portion of cover member 161, and this vertically lower portion of cover member 161 constitutes storage tank 133.

[0045] The heating unit 162 heats the liquid plasma raw material 101. The heating unit 162 is located vertically below the cover member 161, i.e., on the outer periphery of the reservoir 133, and heats the liquid plasma raw material 101 via the cover member 161. Alternatively, the heating unit 162 may be located inside the reservoir 133 and heat the liquid plasma raw material 101 directly.

[0046] The raw material supply unit 163 supplies the liquid plasma raw material 101 to the storage tank 133. As shown in Figure 2, the raw material supply unit 163 has a raw material introduction path 171, a raw material inlet 172, and a raw material supply port 173. In Figure 2, the movement of the solid plasma raw material 141 is indicated by white arrows.

[0047] As shown in Figure 2, the raw material inlet path 171 is a cylindrical passage through which the solid plasma raw material 141 passes. The solid plasma raw material 141 is a plasma raw material in a solid phase, and when the solid plasma raw material 141 melts, it becomes the liquid plasma raw material 101. The solid plasma raw material 141 is a metal or alloy in a solid phase. There are no particular restrictions on the shape of the solid plasma raw material 141, but it may be spherical, for example.

[0048] As shown in Figure 2, raw material inlet path 171 extends from the outside of cover member 161 toward storage tank 133 and is a passage through which solid plasma raw material 141 can pass. As shown in Figure 2, raw material inlet path 171 is formed by an outer peripheral member 174 that surrounds the periphery in a tubular shape. Hereinafter, the end of raw material inlet path 171 on the storage tank 133 side will be referred to as storage tank side end 171a. Storage tank side end 171a is provided with a stopper 175 that closes raw material inlet path 171 and keeps solid plasma raw material 141 within raw material inlet path 171. Stopper 175 may be made of the same material as outer peripheral member 174, or a different material.

[0049] As shown in FIG. 2 , if the extension direction of the raw material introduction channel 171 is defined as extension direction D, extension direction D includes a component C that is directed vertically downward, and the solid plasma raw material 141 is configured to move toward the storage tank 133 due to gravity.

[0050] The raw material inlet 172 is provided near the end of the raw material introduction path 171 opposite the reservoir tank 133, and is an opening through which the solid plasma raw material 141 is introduced. The raw material inlet 172 may be any opening as long as the solid plasma raw material 141 can pass through.

[0051] Raw material supply port 173 is provided in raw material introduction path 171 and is an opening through which liquid plasma raw material 101 passes. Raw material supply port 173 is provided vertically below raw material introduction path 171 at reservoir tank side end 171a of raw material introduction path 171, and can be an opening provided in stopper 175 as shown in Figure 2. Raw material supply port 173 is configured so that solid plasma raw material 141 cannot pass through, but liquid plasma raw material 101 can.

[0052] Specifically, raw material supply port 173 has a shape and size that does not allow passage of solid plasma raw material 141. As shown in Figure 2, if the minimum width of solid plasma raw material 141 is width W1 and the maximum width of raw material supply port 173 is width W2, width W2 is smaller than width W1.

[0053] 2 shows a case where the solid plasma raw material 141 is spherical and the raw material supply port 173 is circular, but in this case, width W2, which is the diameter of the raw material supply port 173, is smaller than width W1, which is the diameter of the solid plasma raw material 141. Similarly, width W2 is smaller than width W1 when the solid plasma raw material 141 and raw material supply port 173 have other shapes. Any other shape may be used for raw material supply port 173 as long as it does not allow the solid plasma raw material 141 to pass through but allows the liquid plasma raw material 101 to pass through.

[0054] The raw material supply unit 163 has the above-described configuration. The raw material supply unit 163 is configured so that the vicinity of the storage tank side end 171a is heated by the heating unit 162. Specifically, when the heating unit 162 generates heat, the stopper 175 and the peripheral member 174 in the vicinity thereof are heated by heat conduction via the liquid plasma raw material 101 stored in the storage tank 133 and the cover member 161. Alternatively, a heating unit separate from the heating unit 162 may be provided near the storage tank side end 171a to directly heat the storage tank side end 171a.

[0055] Figure 3 is a schematic diagram showing the introduction of plasma raw material by the raw material supply unit 163. As shown in Figure 2, when solid plasma raw material 141 is introduced into raw material inlet 172, the solid plasma raw material 141 moves within raw material inlet channel 171 due to gravity and stops when it comes into contact with stopper 175. Because stopper 175 and outer peripheral member 174 at reservoir side end 171a are heated by heating unit 162, as shown in Figure 3, the solid plasma raw material 141 within raw material inlet channel 171 gradually melts, generating liquid plasma raw material 101. The generated liquid plasma raw material 101 passes through raw material supply port 173 and flows into reservoir 133.

[0056] In the plasma generation mechanism 106, the liquid plasma raw material 101 is supplied to the storage tank 133 in the manner described above. The solid plasma raw material 141 passes through the raw material inlet path 171 in a solid state and melts at the storage tank end 171a, so only the storage tank end 171a needs to be heated, thereby reducing the energy required for heating. For example, if the solid plasma raw material 141 is tin, the melting point of tin is 232°C, so heating the entire supply path above its melting point would require a large amount of energy, but the plasma generation mechanism 106 makes it possible to reduce this amount of energy.

[0057] Furthermore, since molten metals such as tin are corrosive, it is necessary to use a corrosion-resistant coating or corrosion-resistant material in the supply path. In the plasma generation mechanism 106, the liquid plasma raw material 101 passes only near the raw material supply port 173, so the corrosion-resistant coating or corrosion-resistant material can be used in only a few places, thereby reducing manufacturing costs.

[0058] Furthermore, when supplying molten metal to a storage tank, a valve is required to supply it at the appropriate time. This valve must be expensive and able to withstand the high temperature of the molten metal, and even if an expensive valve is used, its lifespan is limited. On the other hand, with the plasma generation mechanism 106, the solid plasma raw material 141 can be simply fed into the raw material inlet 172 at any time, eliminating the need for a valve and making it possible to reduce manufacturing and maintenance costs.

[0059] 3, height H is the height of the bottom end of solid plasma raw material 141 located at storage tank side end 171a of raw material supply unit 163. Raw material supply unit 163 is configured so that liquid level 101a stored in storage tank 133 does not exceed height H, that is, so that the height at which liquid level 101a contacts only the bottom end of solid plasma raw material 141 is the upper limit of the height of liquid level 101a.

[0060] When the liquid surface 101a exceeds height H and the solid plasma raw material 141 is immersed in the liquid plasma raw material 101, the liquid plasma raw material 101 is cooled by contact with the solid plasma raw material 141, and the energy required to keep the liquid plasma raw material 101 molten increases.

[0061] Therefore, by configuring the raw material supply unit 163 so that the liquid surface 101a does not exceed height H, it is possible to prevent the solid plasma raw material 141 from cooling the liquid plasma raw material 101 and to prevent destabilization of the output of radiation R. Note that there is no problem if the liquid surface 101a is less than height H, i.e., if the solid plasma raw material 141 is separated from the liquid surface 101a.

[0062] 4 and 5 are schematic diagrams showing a specific configuration of the raw material supply section 163, with FIG. 4 being a cross-sectional view of the rotator unit 150 as seen from vertically above, and FIG. 5 being a cross-sectional view taken along line A-A in FIG. 4. As shown in the figures, the raw material supply section 163 is provided on the rear side of the rotation surface 120a of the cover member 161 that houses the rotator 120, and the raw material introduction path 171 can be a hole formed in the cover member 161. In this case, the outer peripheral member 174 shown in FIG. 2 and the like corresponds to the cover member 161. Alternatively, the raw material introduction path 171 may be formed by inserting the tubular outer peripheral member 174 into a hole formed in the cover member 161.

[0063] [Various Configurations of the Raw Material Supply Unit] A description will be given of various configurations of the raw material supply unit 163. FIG.

[0064] The raw material supply port 173 may be composed of a plurality of minute holes. There are no particular restrictions on the shape of the holes, and the raw material supply port 173 may be in the form of a louver or mesh opening. In addition, the raw material supply port 173 may be any port as long as it does not allow the solid plasma raw material 141 to pass through but allows the liquid plasma raw material 101 to pass through.

[0065] Furthermore, the position of the raw material supply port 173 is not limited to being on the stopper 175. As shown in FIG. 6, the raw material supply port 173 may be formed between the stopper 175 and the outer peripheral member 174. As shown in the figure, the stopper 175 does not completely close the storage tank side end 171a of the outer peripheral member 174, and a gap serving as the raw material supply port 173 can be formed between the stopper 175 and the outer peripheral member 174 on the vertically lower side. Alternatively, the stopper 175 can be positioned slightly spaced apart from the outer peripheral member 174, and a gap serving as the raw material supply port 173 can be formed between the stopper 175 and the outer peripheral member 174. Furthermore, the raw material supply port 173 may be provided on the vertically lower side of the outer peripheral member 174.

[0066] The shape of raw material inlet path 171 is not limited to a straight line, and may be curved or bent. In addition, raw material inlet path 171 may have any shape that allows solid plasma raw material 141 introduced into raw material inlet 172 to be transported by gravity to the vicinity of raw material supply port 173.

[0067] Furthermore, the raw material supply unit 163 does not necessarily have to be equipped with a stopper 175. The raw material introduction path 171 can also be shaped so that its diameter gradually decreases near the reservoir tank side end 171a. The solid plasma raw material 141 introduced through the raw material inlet 172 stops upon contact with the outer peripheral member 174, and the generated liquid plasma raw material 101 flows into the reservoir tank 133 through the raw material supply port 173.

[0068] Alternatively, raw material inlet path 171 may be bent vertically upward near reservoir tank end 171 a. Solid plasma raw material 141 introduced through raw material inlet 172 stops at the bottom of raw material inlet path 171 due to gravity, and the generated liquid plasma raw material 101 flows into reservoir tank 133 through raw material supply port 173.

[0069] Furthermore, raw material supply unit 163 may be equipped with a vacuum exhaust port. The vacuum exhaust port is an opening provided in raw material inlet path 171, connects raw material inlet path 171 to a vacuum exhaust path (not shown), and is used to evacuate raw material inlet path 171. By evacuating raw material inlet path 171 via the vacuum exhaust port, the pressure difference between the inside of cover member 161 (see FIG. 2) and the inside of raw material inlet path 171 is eliminated, and mid-flow stoppage of solid plasma raw material 141 due to the pressure difference can be prevented. The vacuum exhaust port may be provided anywhere in raw material inlet path 171. Furthermore, raw material supply port 173 may have any of the above configurations.

[0070] [About the present disclosure] It is possible to combine at least two of the above-described features of the present technology. Furthermore, the various effects described above are merely examples and are not intended to be limiting, and other effects may also be achieved.

[0071] DESCRIPTION OF SYMBOLS 100... Light source device 101... Liquid plasma raw material 106... Plasma generation mechanism 108... Beam source 120... Rotating body 131... Rotation drive source 132... Shaft portion 133... Storage tank 141... Solid plasma raw material 150... Rotating body unit 161... Cover member 162... Heating portion 163... Raw material supply portion 171... Raw material introduction path 172... Raw material inlet 173... Raw material supply port 174... Peripheral member 175... Stopper

Claims

1. A plasma generation mechanism provided in a light source device which converts a liquid plasma raw material, which is a molten plasma raw material, into plasma by irradiating it with an energy beam and extracts radiation, comprising: a rotor which rotates about a rotation axis; a rotary drive source which rotates said rotor about said rotation axis; a storage tank which stores the liquid plasma raw material and in which a portion of said rotor is immersed in the stored liquid plasma raw material; a heating unit which heats the liquid plasma raw material stored in the storage tank; a raw material inlet path through which a solid plasma raw material, which is the plasma raw material in a solid state, passes; and a raw material supply unit which is provided in the raw material inlet path and has a raw material supply port through which the solid plasma raw material cannot pass but through which the liquid plasma raw material formed by melting the solid plasma raw material can pass, and through which the liquid plasma raw material which has passed through the raw material supply port flows into the storage tank.

2. A plasma generation mechanism as claimed in claim 1, wherein the raw material supply port is configured so that the solid plasma raw material does not come into contact with the liquid surface of the liquid plasma raw material stored in the storage tank, or so that only the lower end of the solid plasma raw material comes into contact with the liquid surface.

3. A plasma generation mechanism according to claim 1, wherein the maximum width of the raw material supply port is smaller than the minimum width of the solid plasma raw material.

4. A plasma generation mechanism according to claim 1, wherein said heating section further heats and melts said solid plasma raw material located within said raw material introduction passage.

5. A plasma generation mechanism according to claim 1, wherein the raw material supply section comprises an outer peripheral member which forms the outer periphery of the cylindrical raw material inlet passage, and a stopper which is provided at the end of the raw material inlet passage on the reservoir tank side and which keeps the solid plasma raw material within the raw material inlet passage.

6. A plasma generation mechanism according to claim 5, wherein the heating section further heats and melts the solid plasma raw material held by the stopper.

7. A plasma generation mechanism according to claim 1, wherein the rotating body has a rotation surface onto which the energy beam is incident.

8. A plasma generation mechanism according to claim 7, wherein the raw material supply unit is provided on the rear side of the rotation surface of a cover member that houses the rotor and forms the storage tank.

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

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

11. A light source device that converts a liquid plasma raw material, which is a molten plasma raw material, into plasma by irradiating it with an energy beam and extracts radiation, comprising: a rotor that rotates around a rotation axis; a rotary drive source that rotates the rotor around the rotation axis; a storage tank that stores the liquid plasma raw material and in which a portion of the rotor is immersed in the stored liquid plasma raw material; a heating unit that heats the liquid plasma raw material stored in the storage tank; a raw material inlet path through which a solid plasma raw material, which is the plasma raw material in a solid state, passes; and a raw material supply unit that is provided in the raw material inlet path and has a raw material supply port through which the solid plasma raw material cannot pass but through which the liquid plasma raw material formed by melting the solid plasma raw material can pass, and through which the liquid plasma raw material that has passed through the raw material supply port flows into the storage tank; and a beam source that irradiates the energy beam onto the rotation surface.

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