Plasma generation mechanism and light source device

Abstract

Provided are a plasma generation mechanism and a light source device capable of preventing the deposition of debris caused by plasma generation.　A plasma generation mechanism according to one embodiment of the present invention is provided with a light source device that extracts radiation by converting a liquid plasma raw material into plasma by irradiation with an energy beam. The plasma generation mechanism comprises a rotating body, a rotation driving source, a raw material supply unit, a shielding part, a heating mechanism, and a liquid guiding part. The rotating body has a rotation surface that rotates around a rotation axis. The rotation driving source rotates the rotating body around the rotation axis. The raw material supply unit supplies the plasma raw material to the rotation surface. The shielding part faces an irradiation position of the rotation surface which is irradiated with the energy beam. The heating mechanism heats the shielding part to a temperature greater than or equal to the melting point of the plasma raw material. The liquid guiding part guides, to the raw material supply unit, the plasma raw material introduced from the shielding part.

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] However, when a plasma raw material is irradiated with a laser beam, debris, which is vapor and fumes of the plasma raw material, is generated along with the plasma. As described in Patent Document 1, when a laser beam is irradiated onto the surface of a rotor coated with a plasma raw material, a large amount of debris is ejected in the direction normal to the rotor surface and adheres to an area of ​​the rotor cover facing the irradiated area (hereinafter referred to as the "facing area").

[0007] The stored plasma raw material is heated by a heater and melted, but the heat does not reach the vicinity of the facing region, so the debris adhering to the facing region solidifies. If a large amount of debris is ejected, the debris will accumulate in the direction of its arrival, which could affect the EUV light emission mechanism.

[0008] Furthermore, of the plasma raw material that adheres to the surface of the rotating body, the plasma raw material that is not irradiated with the laser light is returned to the storage tank and reused. However, if debris accumulates in the opposing region, the plasma raw material does not return to the storage tank, and the stored plasma raw material decreases. In particular, if the laser light irradiation frequency is high, the amount of plasma raw material that is depleted increases, making it necessary to replenish it early.

[0009] In view of the above circumstances, an object of the present invention is to provide a plasma generation mechanism and a light source device that are capable of preventing the accumulation of debris that occurs as a result of plasma generation.

[0010] In order to achieve the above object, one embodiment of the present invention provides a plasma generation mechanism included in a light source device that converts a liquid plasma raw material into plasma by irradiating it with an energy beam to extract radiation, and includes a rotor, a rotary drive source, a raw material supply unit, a shielding unit, a heating mechanism, and a liquid guide unit. The rotor has a rotation surface that rotates around a rotation axis. The rotary drive source rotates the rotor around the rotation axis. The raw material supply unit supplies the plasma raw material to the rotation surface. The shielding unit faces an irradiation position on the rotation surface where the energy beam is irradiated. The heating mechanism heats the shielding unit to a temperature equal to or higher than the melting point of the plasma raw material. The liquid guide unit guides the plasma raw material flowing in from the shielding unit to the raw material supply unit.

[0011] According to this configuration, liquid plasma raw material is supplied to the rotating surface from the raw material supply unit, and when an energy beam is irradiated onto the irradiation position on the rotating surface, plasma is generated and debris is ejected. The debris reaches the shielding unit opposite the irradiation position, but because the shielding unit is heated to a temperature above the melting point of the plasma raw material, the debris that reaches the shielding unit melts and becomes liquid plasma raw material, which returns to the raw material supply unit via the liquid guide unit. This makes it possible to reuse the plasma raw material that has become debris, reducing the frequency of replenishment of the plasma raw material. Furthermore, because the debris does not accumulate on the shielding unit, the adverse effect of the debris on radiation emission can be avoided.

[0012] The raw material supply unit may have a storage tank that stores the plasma raw material that flows in from the liquid guide unit, and a portion of the rotation surface of the rotor may be immersed in the plasma raw material stored in the storage tank.

[0013] The heating mechanism may be disposed on the opposite side of the shielding part from the rotor.

[0014] The heating mechanism may be disposed in the reservoir.

[0015] The plasma generation mechanism may further include a cover that surrounds the rotating body and has an opposing surface that faces the rotating surface, an opening being provided in the opposing surface, and the shielding portion may have a shielding surface that faces the irradiation position via the opening.

[0016] The shielding surface may be further away from the rotation surface than the opposing surface.

[0017] The raw material supply section may have a storage tank that stores the plasma raw material that flows in from the liquid guide section, and the opposing surface may coincide with the periphery of the storage tank when viewed from a direction perpendicular to the rotation axis.

[0018] The plasma processing apparatus may further include a cover surrounding the rotating body and having an opposing surface facing the rotating surface, the opposing surface being located between the liquid guiding section and the raw material supply section, and the liquid guiding section may cause the plasma raw material flowing in from the shielding section to flow onto the opposing surface.

[0019] The shielding portion may have a shielding surface facing the irradiation position, and the liquid guiding portion may have a liquid guiding surface that gradually approaches the rotation surface from the shielding surface toward the facing surface.

[0020] The liquid-guiding surface may be an inclined surface.

[0021] The liquid-guiding surface may be curved.

[0022] The shielding surface may have grooves through which the plasma raw material flows.

[0023] The shielding surface and the liquid-guiding surface may be hemispherical and at a certain distance from the irradiation position.

[0024] The plasma generation mechanism may further include a cover surrounding the rotating body and having an opposing surface facing the rotating surface, and a shield having the shielding portion and the liquid guide portion and detachable from the cover.

[0025] The energy beam may be a laser beam.

[0026] The radiation may be extreme ultraviolet light or x-rays.

[0027] The plasma feedstock may be tin, lithium, gadolinium, terbium, gallium, bismuth, or an alloy containing at least one of these materials.

[0028] To achieve the above object, one aspect of the present invention provides a light source device that converts a liquid 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 having a rotation surface that rotates around an axis of rotation, a rotary drive source that rotates the rotor about the axis of rotation, a raw material supply unit that supplies the plasma raw material to the rotation surface, a shielding unit that faces an irradiation position on the rotation surface where the energy beam is irradiated, a heating mechanism that heats the shielding unit to a temperature equal to or higher than the melting point of the plasma raw material, and a liquid guide unit that guides the plasma raw material that flows in from the shielding unit to the raw material supply unit. The beam source irradiates the energy beam at the irradiation position.

[0029] According to the present invention, it is possible to provide a plasma generation mechanism and a light source device that are capable of preventing the accumulation of debris that occurs as a result of plasma generation.

[0030] 1 is a schematic diagram of a light source device according to a first embodiment of the present invention; FIG. 1 is an enlarged view of a partial configuration of the light source device; FIG. 1 is a schematic diagram of a plasma generation mechanism provided in the light source device; FIG. 2 is a perspective view of a rotating body unit provided in the plasma generation mechanism; FIG. 2 is a cross-sectional view of the rotating body unit; FIG. 3 is an exploded perspective view of the rotating body unit; FIG. 4 is a perspective view of a second cover member provided in the rotating body unit; FIG. 4 is a cross-sectional view of the second cover member; FIG. 5 is a cross-sectional view of the rotating body unit; FIG. 6 is a cross-sectional view of a partial configuration of the rotating body unit; FIG. 7 is a schematic diagram showing the operation of the rotating body unit; FIG. 8 is a cross-sectional view of the rotating body unit; FIG. 9 is a cross-sectional view of a rotating body unit having another configuration; FIG. 10 is a cross-sectional view of a partial configuration of the rotating body unit; FIG. 11 is a perspective view of a rotating body unit having another configuration; FIG. 12 is a cross-sectional view of a partial configuration of the rotating body unit; FIG. 13 is a perspective view of an enlarged portion of the rotating body unit; FIG. 14 is a cross-sectional view of a partial configuration of the rotating body unit; FIG. 15 is a cross-sectional view of a partial configuration of the rotating body unit; FIG. 16 is a perspective view of a shield provided in the rotating body unit; FIG. 17 is a cross-sectional view of a partial configuration of the rotating body unit; FIG. 18 is an exploded perspective view of a shield provided in the rotating body unit; FIG. 19 is a cross-sectional view of a partial configuration of the rotating body unit; FIG. 19 is a perspective view of a second cover member provided in the rotating body unit.

[0031] First Embodiment A light source device according to a first embodiment of the present invention will be described.

[0032] [Basic Configuration of Light Source Device] Fig. 1 is a schematic diagram showing an example of the configuration of a light source device 100 according to this embodiment, and Fig. 2 is a schematic diagram showing an enlarged portion of the light source device 100. 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 irradiates a plasma raw material 101 with an energy beam EB to excite the 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.

[0033] The plasma raw material 101 is liquid and is tin (Sn), lithium (Li), gadolinium (Gd), terbium (Tb), gallium (Ga), bismuth (Bi), 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 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 plasma raw material 101.

[0034] 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.

[0035] 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.

[0036] In the example shown in Fig. 1, the housing 102 is configured so that its outer shape is roughly cubic. The shape of the housing 102 is not limited to a cubic shape, and any three-dimensional shape may be used. The housing 102 has an exit hole 102a formed on the front surface, an entrance hole 102b formed on the right side surface, and a through-hole 102c formed on the left side surface. The material of the housing 102 is not limited, and for example, metal is used.

[0037] In this embodiment, the emission axis EA of the radiation R is set so as to pass through the emission hole 102a on the front surface and extend substantially in the Y direction (front-rear direction). The radiation R is extracted along the emission axis EA and emitted forward from the emission hole 102a. In this embodiment, the incident axis IA of the energy beam EB is set so as to extend obliquely left toward the rear from the entrance hole 102b on the right surface.

[0038] 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 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. The beam source 108 may be configured in any manner that is capable of emitting such an energy beam EB.

[0039] 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.

[0040] 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. Also, a plasma generation mechanism 106 that generates plasma P is arranged in the vacuum chamber 103.

[0041] In this embodiment, the chamber section C (vacuum chamber 103, entrance chamber 104, and exit chamber 105) is configured by the chamber body 109, an outer protrusion 109a protruding forward from the front surface of the chamber body 109, and two inner protrusions 109b and 109c protruding inward from the inner peripheral surface of the chamber body 109. A metal material is used as the material of the chamber body 109.

[0042] The chamber body 109 is configured so that its outer shape is roughly a rectangular parallelepiped, and is disposed so that its front, rear, left, and right faces face the front, rear, left, and right faces of the housing 102. The chamber body 109 is also disposed so that its right front corner between the front face and right face is located on the incidence axis IA of the energy beam EB.

[0043] 1 , an emission hole 109d is formed in the front surface of the chamber main body 109. The emission hole 109d is formed at a position aligned with the emission hole 102a in the front surface of the housing 102 on the emission axis EA of the radiation R. An outer protrusion 109a is formed so as to protrude forward from the periphery of the emission hole 109d of the chamber main body 109. The outer protrusion 109a is configured to protrude farther forward than the emission hole 102a of the housing 102 so as to be inscribed within the emission hole 102a of the housing 102.

[0044] Furthermore, an inner protrusion 109b is formed inside the chamber main body 109 so as to protrude inward from the periphery of the emission hole 109d. The space surrounded by the outer protrusion 109a and the inner protrusion 109b functions as the emission chamber 105. The outer protrusion 109a and the inner protrusion 109b that constitute the emission chamber 105 can also be called the emission chamber. The outer protrusion 109a and the inner protrusion 109b may be formed integrally with the chamber main body 109, or may be formed separately and then connected to the chamber main body 109. Furthermore, the inner protrusion 109b does not necessarily have to be provided.

[0045] The exit chamber 105 is configured to have a cone shape with the exit axis EA of the radiation R as its central axis. The exit chamber 105 is configured so that, in the direction along the exit axis EA of the radiation R, the cross-sectional area is large in the center and becomes smaller toward the front and rear ends. In other words, the exit chamber 105 has a shape that narrows toward the front and rear ends. The exit chamber 105 also has openings (apertures) at the front and rear ends that allow the radiation R to pass through.

[0046] A utilization device such as a mask inspection device is connected to the front end of the extraction chamber 105 (the front end of the outer protrusion 109a). In the example shown in FIG. 1, an application chamber 110 is connected as a chamber that forms part of the utilization device. The pressure inside the application chamber 110 may be atmospheric pressure. Furthermore, the inside of the application chamber 110 may be purged by introducing a gas (e.g., an inert gas) through a gas injection path, as necessary. Furthermore, the gas inside the application chamber 110 may be exhausted by exhaust means (not shown).

[0047] A filter film 111 is provided between the extraction chamber 105 and the application chamber 110 to physically separate the region where plasma P is generated from the application chamber 110. The filter film 111 has a structure that allows radiation R to pass through, and prevents the plasma raw material 101 and debris that are scattered as plasma P is generated from entering the application chamber 110.

[0048] A collector (condensing mirror) 112 is disposed inside the exit chamber 105 to guide and condense the radiation R that has entered the exit chamber 105 into a utilization device (inside the application chamber 110). In Figure 1, the components of the radiation R that enter the exit chamber 105 and are condensed are indicated by hatching.

[0049] A shielding member (central obscuration) 113 is also disposed inside the emission chamber 105. The shielding member 113 is disposed on the emission axis EA of the radiation R so as to be aligned with the emission hole 109d of the chamber body 109, the emission hole 102a of the housing 102, and the filter film 111. In this embodiment, the shielding member 113 can block radiation components that are not collected by the collector 112. Note that the shielding member 113 does not necessarily have to be provided.

[0050] An entrance window 114 is provided at the front right corner of the chamber body 109. The entrance window 114 is disposed on the entrance axis IA of the energy beam EB at a position aligned with the entrance hole 102b on the right side of the housing 102. Furthermore, an inner protrusion 109c is formed on the inside of the front right corner of the chamber body 109 so as to protrude from a position surrounding the entrance window 114 along the direction of the entrance axis IA of the energy beam EB.

[0051] Of the internal space of the chamber body 109, the space surrounded by the inner protrusion 109c functions as the incident chamber 104. The inner protrusion 109c and the front right corner portion of the chamber body 109 that constitute the incident chamber 104 can also be called the incident chamber. The inner protrusion 109c may be formed integrally with the chamber body 109, or may be formed separately and then connected to the chamber body 109.

[0052] The incidence chamber 104 is configured to have a cone shape with the incidence axis IA of the energy beam EB as its central axis. The incidence chamber 104 is configured so that its cross-sectional area decreases toward the inner end of the chamber body 109 in the direction of the incidence axis IA of the energy beam EB. In other words, the incidence chamber 104 has a shape that narrows toward the inner end. The incidence chamber 104 also has an opening (aperture) at its inner end that allows the energy beam EB to pass through.

[0053] A capture mechanism for capturing scattered plasma raw material 101 and debris is placed inside injection chamber 104. In the example shown in Fig. 1, the capture mechanism is a rotary window 115, which is a plate-shaped rotating member that transmits energy beam EB and captures plasma raw material 101 and debris. By rotating rotary window 115, the effective area of ​​the beam transmission region of rotary window 115 increases, making it possible to reduce the frequency of replacing rotary window 115.

[0054] 1, the extraction chamber 105 and the entrance 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 entrance chamber 104. A gas having a high transmittance to the radiation R is supplied to the extraction chamber 105. A gas having a high transmittance to the energy beam EB is supplied to the entrance chamber 104.

[0055] The gases supplied to the extraction chamber 105 and the incidence chamber 104 may be the same type of gas or different types of gas. For example, argon or helium can be used as gases that have high transmittance for both the energy beam EB and the radiation R. There are no other limitations on the type of gas supplied to the extraction chamber 105 and the incidence chamber 104. By supplying gas, the internal pressure of the extraction chamber 105 and the incidence chamber 104 can be set to a pressure higher than the internal pressure of the vacuum chamber 103, making it possible to suppress the intrusion of debris and the like.

[0056] Of the internal space of the chamber body 109, the space excluding the internal space of the inner protrusion 109b that functions as the emission chamber 105 and the internal space of the inner protrusion 109c that functions as the incidence chamber 104 functions as the vacuum chamber 103. The part that constitutes the vacuum chamber 103 itself can also be called the vacuum chamber.

[0057] As shown in FIG. 1 , the chamber main body 109 has a portion that protrudes outside the housing 102 through a through-hole 102c on the left side surface of the housing 102, and its tip is connected to an exhaust pump 117. The specific configuration of the exhaust pump 117 is not limited, and any pump such as a vacuum pump may be used. The exhaust pump 117 evacuates the vacuum chamber 103, reducing the pressure in the vacuum chamber 103. This suppresses attenuation of the radiation R generated in the vacuum chamber 103. The vacuum chamber 103 does not necessarily have to be a vacuum atmosphere as long as it has a reduced pressure atmosphere relative to the entrance chamber 104 and the exit chamber 105. An inert gas may be supplied into the vacuum chamber 103.

[0058] In this embodiment, a gas outlet 118 is provided so as to extend in the left-right direction toward the region between the incident axis IA and the exit axis EA. The gas outlet 118 is provided on the right side surface of the chamber body 109 via a seal member or the like. The gas outlet 118 is connected to a gas supply device (not shown) and supplies gas into the chamber body 109. In the example shown in FIG. 1 , gas is sprayed from the gas outlet 118 from the right side of the region between the incident axis IA and the exit axis EA toward the left side along the left-right direction. This makes it possible to move debris emitted from the plasma P in a direction away from the incident axis IA and the exit axis EA. The gas outlet 118 may be provided in another location in the chamber body 109 as long as it can supply gas into the chamber body 109.

[0059] 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. 2 , the plasma generation mechanism 106 includes a rotor 120, and an energy beam EB is incident on the rotor 120. 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.

[0060] 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 performing various processes. The control unit 107 may be implemented by a programmable logic device (PLD), such as a field programmable gate array (FPGA), or another device, such as an application specific integrated circuit (ASIC). While the control unit 107 is illustrated schematically as a functional block in FIG. 1 , the location of the control unit 107 may be arbitrarily designed.

[0061] 1 , in this embodiment, a radiological diagnostic unit 119 is provided in a region spatially connected to the vacuum chamber 103 on the front side of the chamber main body 109. The radiological diagnostic unit 119 is disposed at a position where radiation R emitted in a direction different from the emission axis EA of the radiation R is incident. The radiological diagnostic unit 119 measures the state of the radiation R from the plasma P. Here, the state of the radiation R refers to the physical state of the radiation R, such as the intensity, wavelength, and spectrum of the radiation R. For example, the radiological diagnostic unit 119 is configured by a detector that detects the presence or absence of radiation R and a measuring device that measures the radiation output. The measurement results by the radiological diagnostic unit 119 are used for diagnosing the radiation R and for controlling the operation of the raw material dropping device described below.

[0062] [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). Fig. 3 is a schematic diagram of the plasma generation mechanism 106. As shown in Figs. 2 and 3, the plasma generation mechanism 106 includes a rotor 120, a rotary drive source 131, a shaft 132, a storage tank 133, and a film thickness adjustment mechanism 134.

[0063] 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. Storage tank 133 is disposed vertically below rotating body 120 and stores plasma raw material 101.

[0064] The rotating body 120 is disposed in the vacuum chamber 103 and is connected to a shaft portion 132. The rotating body 120 rotates due to the rotation of the shaft portion 132, as shown by an arrow S in Fig. 3. Hereinafter, the rotation axis of the rotating body 120 and the shaft portion 132 will be referred to as a rotation axis M.

[0065] As shown in Figure 3, 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 plasma raw material 101 stored in the storage tank 133, and the plasma raw material 101 adheres to the rotation surface 120a as the rotor 120 rotates. The plasma raw material 101 adhered to the rotation surface 120a is transported to the irradiation position I as the rotor 120 rotates, and is converted into plasma by the energy beam EB irradiated at the irradiation position I.

[0066] 3, film thickness adjustment mechanism 134 is disposed on rotor 120 and adjusts the film thickness of plasma raw material 101 adhering to rotation surface 120a. Film thickness adjustment mechanism 134 is, for example, a structure having a channel structure, and is disposed inside thereof with a predetermined gap so as to sandwich rotor 120, and adjusts the film thickness of plasma raw material 101 by scraping off any plasma raw material 101 that has not flowed into the gap. Film thickness adjustment mechanism 134 is disposed upstream of irradiation position I in the rotation direction of rotor 120, and determines the film thickness of plasma raw material 101 at irradiation position I.

[0067] In the plasma generation mechanism 106, the plasma raw material 101 stored in the storage tank 133 as described above adheres to the rotation surface 120a of the rotor 120 and is transported to the irradiation position I by the rotation of the rotor 120. Therefore, the storage tank 133 functions as a "raw material supply unit" that supplies the plasma raw material 101 to the rotation surface 120a.

[0068] [Configuration of Rotating Body Unit] The plasma generation mechanism 106 includes a rotating body unit that houses the rotating body 120. FIG. 4 is a perspective view showing the configuration of the rotating body unit 150. As shown in the figure, the rotating body unit 150 includes the rotating body 120, a cover 160, and a heating mechanism 180, and the rotating body 120 is housed in the cover 160. Note that the cover 160 and the heating mechanism 180 are omitted from illustration in FIGS. 1 to 3. FIGS. 5 and 6 are cross-sectional views of the rotating body unit 150. FIG. 5 is a cross-sectional view taken along line A1-A1 (X-Y plane) in FIG. 4, and FIG. 6 is a cross-sectional view taken along line A2-A2 (Y-Z plane) in FIG. 4.

[0069] The cover 160 surrounds the rotor 120 to prevent debris from scattering and also forms the storage tank 133. The cover 160 is made up of a first cover member 161 and a second cover member 162. FIG. 7 is an exploded perspective view of the rotor unit 150, showing the first cover member 161 and the second cover member 162 disassembled. As shown in the figure, the rotor 120 is housed inside the cover 160. Furthermore, the plasma raw material 101 is stored in the vertically lower part of the cover 160, and this vertically lower part of the cover 160 forms the storage tank 133. A heating mechanism (not shown) is provided around the storage tank 133, and the plasma raw material 101 stored in the storage tank 133 is heated and melted.

[0070] As shown in Fig. 7, the first cover member 161 has a bottom 161a and a side wall 161b. The bottom 161a has a disk shape and has a through hole 161c provided in the center as shown in Fig. 5. The through hole 161c is a hole through which the shaft 132 is inserted. The side wall 161b has a cylindrical shape and is continuous with the periphery of the bottom 161a.

[0071] As shown in Fig. 7, the second cover member 162 is joined to the side wall portion 161b of the first cover member 161. Fig. 8 is a perspective view of the second cover member 162 as seen from the side opposite the rotation surface 120a, and Fig. 9 is a perspective view of the second cover member 162 as seen from the rotation surface 120a side. Fig. 10 is a cross-sectional view of the second cover member 162, taken along line A3-A3 (YZ plane) in Figs. 8 and 9.

[0072] 8 to 10 , the second cover member 162 has a flat plate portion 163, a shielding portion 164, and a liquid guide portion 165. The flat plate portion 163 has a flat plate shape and faces the rotation surface 120a of the rotor 120 as shown in Fig. 7 . As shown in Fig. 9 , the surface of the flat plate portion 163 facing the rotation surface 120a is defined as an opposing surface 163a. ​​The opposing surface 163a is a surface parallel to the rotation surface 120a, for example, a surface parallel to the vertical direction.

[0073] 9, the flat plate portion 163 is provided with an opening 163b, an entrance hole 166, and an exit hole 167. The opening 163b is an opening formed by recessing the shielding portion 164 into the opposing surface 163a. ​​The entrance hole 166 is provided through the second cover member 162 and is a hole through which the energy beam EB enters. The exit hole 167 is also provided through the second cover member 162 and is a hole through which the radiation R exits.

[0074] The opposing surface 163a forms the storage tank 133 together with the first cover member 161, as shown in Fig. 7. Fig. 11 is a plan view of the cross section of the rotating body unit 150 as seen from a direction perpendicular to the rotation axis M (Z direction), and is a cross section taken along line A4-A4 (X-Y plane) in Fig. 4. In this figure, the periphery T (broken line) of the storage tank 133 is shown. The periphery T is the periphery of the liquid surface of the plasma raw material 101 stored in the storage tank 133. As shown in this figure, the opposing surface 163a coincides with the periphery T when viewed from a direction perpendicular to the rotation axis M (Z direction).

[0075] The shielding portion 164 faces the irradiation position I and shields from debris generated as plasma is generated. FIG. 12 is a cross-sectional view of the vicinity of the shielding portion 164 of the rotating body unit 150, taken along line A2-A2 (YZ plane) in FIG. 4. As shown in the figure, the shielding portion 164 has a shielding surface 164a that faces the irradiation position I on the plane of rotation 120a. The shielding surface 164a is parallel to the plane of rotation 120a and can be, for example, a surface parallel to the vertical direction. Furthermore, the shielding surface 164a does not have to be a surface parallel to the plane of rotation 120a, and may be a curved surface or an inclined surface, as will be described later.

[0076] The shielding surface 164a is recessed from the opposing surface 163a, is farther from the surface of rotation 120a than the opposing surface 163a, and faces the irradiation position I via an opening 163b (see FIG. 10 ) in the opposing surface 163a. ​​As shown in FIG. 8 , the shielding portion 164 has an entrance hole 166 and an exit hole 167 formed continuously with the flat plate portion 163.

[0077] Liquid guide section 165 is provided between shield section 164 and flat plate section 163, and guides plasma raw material 101 flowing in from shield section 164 to storage tank 133, which serves as the raw material supply section. Specifically, as shown in Figure 12, liquid guide section 165 has liquid guide surface 165a located between shield surface 164a and opposing surface 163a.

[0078] Liquid leading surface 165a has a shape that does not retain plasma raw material 101 flowing in from above shielding surface 164a. Specifically, liquid leading surface 165a has a shape that gradually approaches rotation surface 120a from shielding surface 164a toward opposing surface 163a. ​​Figure 10 shows liquid leading surface 165a in a curved shape. Liquid leading surface 165a may also be inclined, as will be described later. Furthermore, the entire liquid leading surface 165a does not have to have a shape that gradually approaches rotation surface 120a, and at least a portion may be horizontal.

[0079] The heating mechanism 180 heats the shielding part 164 to a temperature equal to or higher than the melting point of the plasma raw material 101. As shown in Figure 12, the heating mechanism 180 is placed on the opposite side of the shielding surface 164a of the shielding part 164 and is in contact with the shielding part 164. The heating mechanism 180 may also be placed on the opposite side of the liquid-guiding surface 165a of the liquid-guiding part 165. Furthermore, the heating mechanism 180 may be a heating mechanism placed in the storage tank 133 for melting the plasma raw material 101 stored in the storage tank 133. The heating mechanism 180 is, for example, a resistance heater.

[0080] [Operation and Effects of Light Source Device] The operation and effects of light source device 100 will now be described. Figure 13 is a schematic diagram showing the operation of light source device 100. In rotor unit 150, when rotor 120 rotates as described above, plasma raw material 101 stored in reservoir 133 adheres to rotation surface 120a (see Figure 3). In this state, when energy beam EB is emitted from beam source 108 (see Figure 1), energy beam EB passes through entrance hole 166 (see Figure 4) and enters irradiation position I on rotation surface 120a.

[0081] The energy beam EB converts the plasma raw material 101 into plasma at irradiation position I, generating plasma P as shown in Figure 13. Radiation R (see Figure 2) is emitted from the plasma P and is emitted through the exit hole 167 (see Figure 4). As this plasma is converted into plasma, debris D, which is vapor and mist of the plasma raw material 101, is ejected from irradiation position I as shown in Figure 13. The debris D is ejected mainly along the normal direction H (Y direction) of the plane of rotation 120a.

[0082] Here, because the rotator unit 150 has a shielding surface 164a disposed opposite the irradiation position I, the debris D ejected from the irradiation position I reaches the shielding surface 164a. Because the shielding surface 164a is heated by the heating mechanism 180 to a temperature above the melting point of the plasma raw material 101, the debris D that reaches the shielding surface 164a melts and becomes liquid plasma raw material 101, which flows down the shielding surface 164a (arrow F1 in the figure).

[0083] Plasma raw material 101 that has flowed down shielding surface 164a flows onto liquid-leading surface 165a and continues to flow down liquid-leading surface 165a. Because liquid-leading surface 165a has a shape that does not allow plasma raw material 101 to be stored, plasma raw material 101 flows down liquid-leading surface 165a (arrow F2 in the figure) and onto opposing surface 163a. ​​Plasma raw material 101 that has flowed onto opposing surface 163a flows down on opposing surface 163a (arrow F3 in the figure) and into storage tank 133.

[0084] This allows the ejected plasma raw material 101 to be collected in the storage tank 133 as debris D and reused. If the shielding section 164 were not provided, the debris D would reach the area of ​​the second cover member 162 facing the irradiation position I, solidify, and accumulate. This could cause the entrance hole 166 and exit hole 167 to become blocked, adversely affecting the emission of radiation R. Furthermore, if debris D accumulates, the plasma raw material 101 does not return to the storage tank 133, and the consumption of plasma raw material 101 increases, making it necessary to replenish plasma raw material 101 at short intervals.

[0085] In contrast, in light source device 100, debris D does not accumulate on shielding surface 164a, and therefore does not adversely affect the emission of radiation R. Furthermore, plasma raw material 101 that is ejected as debris D returns to storage tank 133, which reduces the consumption of plasma raw material 101 and makes it possible to reduce the frequency with which plasma raw material 101 is replenished.

[0086] Furthermore, shielding surface 164a is provided at a distance from surface of rotation 120a relative to opposing surface 163a (see FIG. 13). If shielding surface 164a were too close to surface of rotation 120a, there would be a risk that plasma raw material 101 melted on shielding surface 164a would be scattered by shock waves caused by irradiation with energy beam EB. In particular, at irradiation position I, the film thickness of plasma raw material 101 is adjusted by film thickness adjustment mechanism 134, but there is a risk that this film thickness will fluctuate due to scattered plasma raw material 101.

[0087] Furthermore, if the shielding surface 164a is close to the rotation surface 120a, the ejected debris D may collide with the shielding surface 164a and be reflected, adhering to the rotation surface 120a without melting. Fluctuations in the film thickness of the plasma raw material 101 or the adhesion of foreign matter at the irradiation position I can cause the output of radiation R to become unstable. Therefore, by providing the shielding surface 164a at a distance from the rotation surface 120a, these problems can be resolved and the output of radiation R can be stabilized.

[0088] It is also possible to separate opposing surface 163a from rotation surface 120a together with shielding surface 164a, but in that case the volume of storage tank 133 increases, and the energy required to melt stored plasma raw material 101 also increases. For this reason, it is more preferable to separate shielding surface 164a from rotation surface 120a relative to opposing surface 163a.

[0089] [Regarding the Shape of the Shielding Section and the Liquid Guide Section] The shielding section 164 and the liquid guide section 165 may also have the following shapes. FIG. 14 is a perspective view of a rotator unit 150 in which the shielding section 164 and the liquid guide section 165 have other shapes. FIG. 15 is a cross-sectional view of this rotator unit 150, taken along line A5-A5 (X-Y plane) in FIG. 14. As shown in these figures, a gap 168 may be provided between the shielding section 164 and the flat plate section 163. As described above, the debris D generated at the irradiation position I is mainly ejected along the normal direction H (Y direction) of the rotation plane 120a (see FIG. 13). Therefore, even if the gap 168 is provided, almost all of the debris D reaches the shielding surface 164a and is reused.

[0090] Fig. 16 is a perspective view of a rotator unit 150 in which the shielding portion 164 and the liquid guide portion 165 have different shapes. Figs. 17 and 18 are cross-sectional views of this rotator unit 150, with Fig. 17 being a cross-sectional view taken along line A6-A6 (X-Y plane) in Fig. 16 and Fig. 18 being a cross-sectional view taken along line A7-A7 (Y-Z plane) in Fig. 14. As shown in these figures, the shielding portion 164 and the liquid guide portion 165 are hemispherical, and the shielding surface 164a and the liquid guide surface 165a are hemispherical with the irradiation position I as their center. In other words, the liquid guide surface 165a is curved from the shielding surface 164a toward the opposing surface 163a and gradually approaches the rotation surface 120a.

[0091] In this structure, the shielding surface 164a and the liquid-guiding surface 165a are equidistant from the irradiation position I. Since the shock waves caused by the irradiation of the energy beam EB described above spread isotropically, it is possible to suppress the shock waves at the shielding surface 164a and the liquid-guiding surface 165a. It is also possible to suppress the reflection of debris D by the shielding surface 164a and the liquid-guiding surface 165a.

[0092] Fig. 19 is a perspective view of a rotating body unit 150 in which the shielding portion 164 and the liquid guide portion 165 have different shapes. Fig. 20 is an enlarged view of the shielding portion 164. Figs. 21 and 22 are cross-sectional views of this rotating body unit 150, Fig. 21 being a cross-sectional view taken along line A8-A8 (X-Y plane) in Fig. 19, and Fig. 22 being a cross-sectional view taken along line A9-A9 (Y-Z plane) in Fig. 19. As shown in these figures, the shielding portion 164 and the liquid guide portion 165 have shapes that are mainly planar in structure.

[0093] Specifically, the shielding surface 164a has a shape such that its center is farthest from the rotation surface 120a in the horizontal plane (X-Y plane). The liquid-guiding surface 165a has a center that is farthest from the rotation surface 120a in the horizontal plane (X-Y plane), and is an inclined surface that gradually approaches the rotation surface 120a from the shielding surface 164a toward the opposing surface 163a. ​​Hereinafter, the valley-shaped portion farthest from the rotation surface 120a in the centers of the shielding surface 164a and the liquid-guiding surface 165a will be referred to as the liquid collecting portion 169.

[0094] As shown in Figures 20 and 21, grooves 170 are provided on shielding surface 164a. Grooves 170 guide plasma raw materials 101 that flow down grooves 170 to liquid-guiding surface 165a, so that plasma raw materials 101 that flow down grooves 170 are collected in liquid-collecting sections 169 and easily flow from liquid-collecting sections 169 onto opposing surface 163a. ​​By making shielding section 164 and liquid-guiding section 165 primarily planar in shape, manufacturing is facilitated. Note that although heating mechanism 180 is provided only on shielding section 164 in Figure 19, it may also be provided on liquid-guiding section 165.

[0095] Fig. 23 is a perspective view of a rotating body unit 150 in which the shielding portion 164 and the liquid guide portion 165 have another configuration, and Fig. 24 is an exploded perspective view of a portion of the configuration. Fig. 25 is a cross-sectional view of this rotating body unit 150, taken along line A10-A10 (X-Y plane) in Fig. 23. As shown in these figures, the rotating body unit 150 may have a shielding body 190 that is detachable from the second cover member 162, and the shielding body 190 may have the shielding portion 164 and the liquid guide portion 165.

[0096] 26 is a perspective view of the second cover member 162 in this case. As shown in the figure, the second cover member 162 is not provided with a shielding portion 164 or a liquid guide portion 165, and the flat plate portion 163 is provided with an opening 163b, a through hole 163c, an entrance hole 166, and an exit hole 167.

[0097] 24 , the shield 190 has a shielding portion 164, a liquid guide portion 165, an engaging portion 191, and a through hole 192. As shown in the same figure, a stud 193 is inserted into the through hole 163c. The shield 190 is fixed to the second cover member 162 by engaging the engaging portion 191 with the opening 163b and fastening a screw 194 to the stud 193 through the through hole 192. The shield 190 can be removed from the second cover member 162 by removing the screw 194. The number of studs 192 is, for example, two, but may be one or three or more.

[0098] Engagement portion 191 is provided at the end of liquid guiding portion 165 opposite shielding portion 164, and abuts against opposing surface 163a around opening 163b, fixing the lower portion of shielding body 190 to second cover member 162. Engagement portion 191 is preferably shaped so that it continues from liquid guiding surface 165a and overlaps opposing surface 163a to prevent leakage of plasma raw material 101.

[0099] In this configuration, the shield 190 is detachable from the second cover member 162, allowing for replacement of the shield 190. As described above, the shielding surface 164a is the surface that is directly hit by debris ejected from the irradiation position I, and therefore needs to be replaced at predetermined intervals. Since this configuration allows for replacement of the shield 190, it is easy to maintain.

[0100] In addition to the above, the shielding section 164 and the liquid guiding section 165 can have various other configurations, and the shielding section 164 need only face the irradiation position I. The liquid guiding section 165 need only be capable of guiding the plasma raw material 101 flowing in from the shielding section 164 to the storage tank 133. In various configurations, the shielding surface 164a can be provided with a groove 170 that guides the plasma raw material 101 to the liquid guiding surface 165a.

[0101] (Regarding the Present Disclosure) In the present disclosure, when the word "approximately" is used, this is used merely to facilitate understanding of the description, and the use or non-use of the word "approximately" does not have any special meaning. That is, in the present disclosure, concepts that define shape, size, positional relationship, state, etc., such as "center," "central," "uniform," "equal," "same," "orthogonal," "parallel," "symmetrical," "extended," "axial direction," "circular," "arc-shaped," "rectangular," "rectangular," "polygonal," "ring-shaped," "cubic," "cuboid," "cylindrical," "disk-shaped," and "cone-shaped," are concepts that include "substantially center," "substantially central," "substantially uniform," "substantially equal," "substantially the same," "substantially orthogonal," "substantially parallel," "substantially symmetrical," "substantially extended," "substantially axial," "substantially circular," "substantially arc-shaped," "substantially rectangular," "substantially rectangular," "substantially polygonal," "substantially ring-shaped," "substantially cubic," "substantially rectangular," "substantially cylindrical," "substantially disk-shaped," "substantially cone-shaped," etc. For example, states that fall within a predetermined range (e.g., a range of ±10%) based on standards such as "perfectly centered," "perfectly central," "perfectly uniform," "perfectly equal," "perfectly the same," "perfectly orthogonal," "perfectly parallel," "perfectly symmetrical," "perfectly extended," "perfectly axial," "perfectly circular," "perfectly arc-shaped," "perfectly rectangular," "perfectly oblong," "perfectly polygonal," "perfectly ring-shaped," "perfectly cubic," "perfectly rectangular," "perfectly cylindrical," "perfectly disk-shaped," and "perfectly cone-shaped" are also included. Therefore, even if the word "approximately" is not added, a concept expressed by adding "approximately" may be included. Conversely, a state expressed by adding "approximately" does not exclude a perfect state.

[0102] In the present disclosure, expressions using "than", such as "greater than A" and "smaller than A", are expressions that comprehensively include both concepts that include the case where it is equivalent to A and concepts that do not include the case where it is equivalent to A. For example, "greater than A" is not limited to cases that do not include equivalent to A, but also includes "A or greater". Furthermore, "smaller than A" is not limited to "less than A" but also includes "A or less". When implementing the present technology, specific settings and the like can be appropriately adopted from the concepts included in "greater than A" and "smaller than A" so that the effects described above can be achieved.

[0103] It is also possible to combine at least two of the features of the present technology described above. That is, the various features described in each embodiment may be combined in any manner without distinguishing between the embodiments. Furthermore, the various effects described above are merely examples and are not intended to be limiting, and other effects may also be achieved.

[0104] DESCRIPTION OF SYMBOLS 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... Shielding portion 165... Liquid guide portion 170... Groove 180... Heating mechanism 190... Shielding body

Claims

1. A plasma generation mechanism provided in a light source device which converts liquid plasma raw material into plasma by irradiating it with an energy beam to extract radiation, the plasma generation mechanism comprising: a rotor having a rotation surface which rotates around an axis of rotation; a rotary drive source which rotates said rotor about said axis of rotation; a raw material supply unit which supplies said plasma raw material to said rotation surface; a shielding unit which faces an irradiation position on said rotation surface where the energy beam is irradiated; a heating mechanism which heats said shielding unit to a temperature equal to or higher than the melting point of the plasma raw material; and a liquid guiding unit which guides the plasma raw material flowing in from the shielding unit to the raw material supply unit.

2. A plasma generation mechanism as claimed in claim 1, wherein the raw material supply section has a storage tank for storing the plasma raw material flowing in from the liquid guide section, and the rotating body has a portion of its rotation surface immersed in the plasma raw material stored in the storage tank.

3. A plasma generation mechanism according to claim 1, wherein the heating mechanism is disposed on the opposite side of the shielding part to the rotor.

4. A plasma generating mechanism according to claim 2, wherein the heating mechanism is disposed in the storage tank.

5. A plasma generation mechanism as claimed in claim 1, further comprising a cover surrounding the rotor and having an opposing surface facing the rotational surface, an opening being provided in the opposing surface, and the shielding portion having a shielding surface facing the irradiation position via the opening.

6. A plasma generating mechanism according to claim 5, wherein the shielding surface is spaced farther from the rotating surface than the opposing surface is.

7. A plasma generation mechanism as described in claim 6, wherein the raw material supply section has a storage tank for storing the plasma raw material flowing in from the liquid guide section, and the opposing surface coincides with the periphery of the storage tank when viewed from a direction perpendicular to the rotation axis.

8. A plasma generation mechanism as described in claim 1, further comprising a cover surrounding the rotor and having an opposing surface facing the rotation surface, the opposing surface being positioned between the liquid guiding section and the raw material supply section, and the liquid guiding section directs the plasma raw material flowing in from the shielding section onto the opposing surface.

9. A plasma generation mechanism as claimed in claim 8, wherein the shielding section has a shielding surface facing the irradiation position, and the liquid guide section has a liquid guide surface which gradually approaches the rotating surface from the shielding surface towards the facing surface.

10. The plasma generating mechanism according to claim 9, wherein the liquid-guiding surface is inclined.

11. The plasma generating mechanism according to claim 9, wherein the liquid-guiding surface is curved.

12. A plasma generation mechanism according to claim 9, wherein the shielding surface has a groove through which the plasma raw material flows.

13. A plasma generating mechanism according to claim 9, wherein the shielding surface and the liquid-guiding surface are hemispherical and equidistant from the irradiation position.

14. A plasma generation mechanism as claimed in claim 1, further comprising a cover surrounding the rotating body and having an opposing surface facing the rotating surface, and a shield having the shielding portion and the liquid guide portion and being detachable from the cover.

15. A plasma generation mechanism according to claim 1, further comprising a film thickness adjustment mechanism for adjusting the film thickness of the plasma raw material on the rotating surface.

16. The plasma generation mechanism according to claim 1, wherein the energy beam is a laser beam.

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

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

19. A light source device that converts liquid plasma raw material into plasma by irradiating it with an energy beam to extract radiation, comprising: a rotating body having a rotational surface that rotates around an axis of rotation, a rotary drive source that rotates said rotating body about said axis of rotation, a raw material supply unit that supplies said plasma raw material to said rotating surface, a shielding unit that faces an irradiation position on said rotating surface where the energy beam is irradiated, a heating mechanism that heats the shielding unit to a temperature equal to or higher than the melting point of the plasma raw material, and a plasma generation mechanism that includes a liquid guiding unit that guides the plasma raw material flowing in from the shielding unit to the raw material supply unit, and a beam source that irradiates the energy beam at said irradiation position.

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