Light-emitting unit

Abstract

A light-emitting unit according to one embodiment of the present technology generates radiation by turning a liquid raw material into plasma by irradiation with an energy beam, and comprises a rotating body and a liquid raw material supply mechanism. The rotating body can rotate about a prescribed rotation axis and is a substantially flat plate. The liquid raw material supply mechanism supplies the liquid raw material to a supply position on the rotating body. As viewed from the extending direction of the rotation axis, the supply position is present at a position closer to the rotation axis in comparison to the irradiation position of the energy beam.

Description

Light-emitting unit

[0001] This invention relates to a light-emitting unit that generates radiation such as X-rays and extreme ultraviolet light.

[0002] Extreme ultraviolet (EUV) light, a type of X-ray, has recently been used as exposure light. The substrate for an EUV lithography mask is constructed by patterning a material that absorbs EUV lithography radiation onto a multilayer film (for example, molybdenum and silicon) that reflects EUV light.

[0003] The size of unacceptable defects in EUV masks has become significantly smaller, making them difficult to detect. Therefore, EUV masks are now inspected using a method called actinic inspection, which uses radiation at wavelengths that match the working wavelengths of lithography.

[0004] Generally, EUV light sources include DPP (Discharge Produced Plasma) light sources, LDP (Laser Assisted Discharge Produced Plasma) light sources, and LPP (Laser Produced Plasma) light sources.

[0005] A DPP (Dynamic Pulsed Power) light source device utilizes extreme ultraviolet light emitted from a high-density, high-temperature plasma generated by a discharge, which is created by applying a high voltage between electrodes supplied with gaseous plasma material (discharge gas) containing EUV emitting species.

[0006] An LDP light source device is an improved version of a DPP light source device. For example, it supplies a liquid high-temperature plasma material containing EUV emitting species (e.g., Sn (tin) or Li (lithium)) to the surface of an electrode that generates a discharge (discharge electrode), irradiates the material with a laser beam to vaporize it, and then generates a high-temperature plasma by discharge.

[0007] LPP (Low-Pressure Pulsed Plasma) light sources generate high-temperature plasma by exciting EUV (Extremely Ultraviolet) radiation species with a laser beam or the like. One known type of light source uses a laser beam focused onto droplets of high-temperature plasma raw material ejected in the form of tiny liquid droplets to excite the target material and generate plasma.

[0008] Patent Document 1 proposes a method for generating radiation such as X-rays and EUV by supplying plasma material to a rotating body and irradiating the region of the rotating body to which the plasma material is supplied with an energy beam (laser beam) to obtain radiation. A cylindrical container with one end open is used as the rotating body, liquid plasma material is supplied to this container, and laser light is irradiated onto the inner surface of the container.

[0009] This method is equivalent to the so-called LPP method, but it supplies liquid plasma material to the energy beam irradiation area using the centrifugal force of a rotating body, eliminating the need to supply liquid plasma material as droplets. Therefore, compared to methods that focus a laser beam onto droplets, it is possible to obtain high-brightness radiation with a relatively simple configuration.

[0010] Japanese Patent Publication No. 2014-216286

[0011] In light source devices such as those described in Patent Document 1, there is a need for a technology that enables the stable emission of radiation.

[0012] In view of the above circumstances, the object of the present invention is to provide a light-emitting unit that can stably emit radiation.

[0013] To achieve the above objective, a light-emitting unit according to one embodiment of this technology is a light-emitting unit that generates radiation by plasmaizing a liquid raw material by irradiation with an energy beam, and comprises a rotating body and a liquid raw material supply mechanism. The rotating body is rotatable about a predetermined axis of rotation and is generally flat. The liquid raw material supply mechanism supplies the liquid raw material to a supply position which is a position on the rotating body. When viewed from the direction of extension of the axis of rotation, the supply position is located closer to the axis of rotation than the irradiation position of the energy beam.

[0014] In this light-emitting unit, a liquid raw material is supplied to a supply position on a rotating body that is roughly flat. Furthermore, when viewed from the direction of the rotation axis of the rotating body, the supply position is located closer to the rotation axis than the irradiation position of the energy beam. This makes it possible to emit radiation stably.

[0015] When viewed from the extending direction of the rotating shaft, the supply position may be located at the same position as the rotating shaft.

[0016] When viewed from the direction of extension of the rotating shaft, the supply position may be located at a position different from that of the rotating shaft.

[0017] The light-emitting unit may further include a cover member that surrounds the rotating body.

[0018] The light-emitting unit may further include a circulation mechanism that supplies the liquid raw material captured by the cover member to the liquid raw material supply mechanism.

[0019] The irradiation position may be a position on the rotating body.

[0020] The irradiation position may be a position other than the position on the rotating body.

[0021] The light-emitting unit may further include a container positioned on the opposite side of the irradiation position from the incident side of the energy beam, with respect to the irradiation position, for capturing debris scattered from the irradiation position.

[0022] The light-emitting unit may further include a circulation mechanism that supplies the debris captured by the container to the liquid raw material supply mechanism.

[0023] The axis of rotation may be parallel to the vertical direction.

[0024] According to the present invention, it becomes possible to stably emit radiation. The effects described herein are not necessarily limited, and any of the effects described in this disclosure may be present.

[0025] This is a schematic diagram showing an example configuration of the light source device according to this embodiment. This is a schematic diagram showing an example configuration of the plasma generation mechanism. This is a schematic diagram showing the relationship between the irradiation position and the supply position. This is a schematic diagram showing an example of variations in the supply position. This is a schematic diagram showing an example of variations in the irradiation position. This is a schematic diagram showing an example of variations in the rotating body. This is a schematic diagram showing an example of variations in the rotating body. This is a schematic diagram showing an example of a configuration in which the cover member has a circulation mechanism. This is a schematic diagram showing an example of a configuration in which the cover member has a circulation mechanism. This is a schematic diagram showing an example of variations in the shape of the rotating body.

[0026] [Basic Configuration of the Light Source Device] Figure 1 is a schematic diagram showing an example of the configuration of the light source device 100 according to this embodiment. The light source device 100 is an LPP type light source device. That is, the light source device 100 is a device that excites a liquid raw material by irradiating (injecting) an energy beam EB into the liquid raw material to generate plasma P, and extracts radiation R emitted from the plasma P to use as a light source. The radiation R is EUV light, X-rays, or other electromagnetic waves.

[0027] The liquid raw material is a molten metal or alloy, such as tin (Sn), lithium (Li), gadolinium (Gd), terbium (Tb), gallium (Ga), bismuth (Bi), indium (In), or an alloy containing at least one of these materials in a liquid phase.

[0028] Figure 1 shows a schematic cross-section of the light source device 100, viewed from the positive side in the Z direction, when the device is cut horizontally at a predetermined height from the installation surface. In Figure 1, parts of the cross-section that do not require explanation are omitted in order to facilitate understanding of the configuration and operation of the light source device 100. Hereafter, the X and Y directions may be referred to as horizontal directions, and the Z direction as vertical directions.

[0029] As shown in Figure 1, the light source device 100 comprises a housing 102, a vacuum chamber 103, an energy beam injection chamber 104, a radiation emission chamber 105, a plasma generation mechanism 106, a control unit 107, and a beam source 108.

[0030] In the example shown in Figure 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 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 to pass through the entrance hole 102b.

[0031] As shown in Figure 1, a beam source 108 that emits an energy beam EB is installed outside the housing 102. The beam source 108 is positioned so that the energy beam EB is incident on the interior of the housing 102 along the incident axis IA. An electron beam or laser light can be used as the energy beam EB.

[0032] The light source device 100 is provided with a chamber section C that includes a plurality of chambers. Specifically, the chamber section C includes a vacuum chamber 103, an energy beam injection chamber (hereinafter simply referred to as the injection chamber) 104, and a radiation emission chamber (hereinafter simply referred to as the emission chamber) 105. The vacuum chamber 103 and the injection chamber 104 are connected to each other, and the vacuum chamber 103 and the emission chamber 105 are connected to each other.

[0033] The injection chamber 104 is configured to be located on the injection axis IA of the energy beam EB, and the exit chamber 105 is configured to be located on the exit axis EA of the radiation R. A focusing mirror 112 for guiding the radiation R is placed inside the exit chamber 105. A plasma generation mechanism 106 for generating plasma P is placed inside the vacuum chamber 103.

[0034] An apparatus for use such as a mask inspection apparatus is connected to the end of the exit chamber 105 on the side opposite to 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 apparatus for use. Further, the inside of the application chamber 110 may be purged by introducing a gas (for example, an inert gas) from a gas injection path as necessary, and may be evacuated by an unillustrated exhaust unit. Between the application chamber 110 and the exit chamber 105, a filter film 111 and an opening for physically separating the region where the plasma P is generated from the application chamber 110 are provided.

[0035] The vacuum chamber 103 is provided with an entrance window 114. The entrance window 114 is arranged at a position aligned with the entrance hole 102b on the incident axis IA of the energy beam EB. Further, an exhaust pump 117 is connected to the vacuum chamber 103.

[0036] Further, as shown in FIG. 1, the exit chamber 105 and the entrance chamber 104 are provided with gas injection paths 116a and 116b respectively, and a gas having high transmittance for the radiation R such as argon or helium and the energy beam EB is supplied into the exit chamber 105 and the entrance chamber 104 from an unillustrated gas supply apparatus.

[0037] The plasma generation mechanism 106 is a mechanism that generates plasma P and emits radiation R. The plasma generation mechanism 106 is accommodated in the vacuum chamber 103. The plasma generation mechanism 106 has a rotating body 20 and a cover member 21 as shown in FIG. 1.

[0038] The energy beam EB is incident on the rotating body 20. The rotating body 20 is arranged such that the irradiation position I of the energy beam EB is arranged at the intersection of the incident axis IA and the exit axis EA.

[0039] A shaft member and a motor are connected to the center of the back surface (the surface on the negative side of the Z axis) of the rotating body 20. When the motor is driven, the shaft member and the rotating body 20 rotate integrally. The direction of rotation of the rotating body 20 is indicated by an arrow in FIG. 1. In this example, the rotating body 20 rotates clockwise when viewed from the positive side of the Z axis, but it may rotate counterclockwise.

[0040] Further details regarding the configuration of the plasma generation mechanism 106 will be explained later. The plasma generation mechanism 106 corresponds to one embodiment of the light-emitting unit related to this technology.

[0041] 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. In Figure 1, the control unit 107 is schematically shown as a functional block, but the location and other aspects of the control unit 107 can be designed arbitrarily.

[0042] As shown in Figure 1, in this embodiment, a radiation diagnostic unit 119 is connected to the vacuum chamber 103. The radiation diagnostic unit 119 is positioned where some of the radiation R', which is 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.

[0043] [Plasma Generation Mechanism] Figure 2 is a schematic diagram showing an example of the configuration of the plasma generation mechanism 106. Figure 2 shows the plasma generation mechanism 106 as viewed from the positive side in the Y direction. In addition to the rotating body 20, cover member 21, and shaft member 22 described above, the plasma generation mechanism 106 also has a supply mechanism 23 and a circulation mechanism 24.

[0044] The rotating body 20 has a generally flat shape and has a circular surface 25 and a circular surface 26. The rotating body 20 is positioned so that the surface 25 and the surface 26 are parallel to the horizontal direction, with the surface 25 on the positive side of the Z direction and the surface 26 on the negative side of the Z direction. The term "generally flat" is a concept that includes not only perfectly flat plates but also flat plates with shapes that are somewhat different from a perfectly flat plate, such as when the surface 25 and the surface 26 are not perfectly parallel. As shown in Figure 2, an energy beam EB is irradiated onto a predetermined irradiation position I on the surface 25.

[0045] The cover member 21 has an overall bowl shape, with a disc-shaped bottom 27 and ring-shaped sides 28. The rotating body 20 is placed in the space enclosed by the bottom 27 and the sides 28. In other words, the rotating body 20 is surrounded by the cover member 21.

[0046] The bottom portion 27 is parallel to the horizontal direction and has a through hole 29 in the center through which the shaft member 22 passes. A recess 30 is formed on the inner circumferential surface of the side portion 28 at approximately the same height as the surface 25. The recess 30 extends around the entire circumference of the inner circumferential surface of the side portion 28. The specific shape of the cover member 21 is not limited.

[0047] The shaft member 22 has a rod shape, with one end connected to the center of the back surface 26 of the rotating body 20, and is arranged parallel to the Z direction. The shaft member 22 passes through the through hole 29 of the cover member 21, and the other end is connected to a motor or the like (not shown). When the motor or the like is driven, the shaft member 22 and the rotating body 20 rotate as a single unit.

[0048] Since the shaft member 22 is positioned in the Z direction, the rotation axis J of the rotating body 20 is also parallel to the Z direction. In other words, in this embodiment, the rotation axis J is parallel to the vertical direction (direction of gravity), and the direction of extension of the rotation axis J is the vertical direction. In Figure 2, the rotation axis J is shown as a dashed line. Otherwise, the rotation axis J may be in any direction, such as slightly tilted with respect to the vertical direction. In this case, the shaft member 22 and the rotating body 20 can also be positioned in any orientation. That is, for example, the surface 25 and back surface 26 of the rotating body 20 may not be parallel to the horizontal direction.

[0049] The supply mechanism 23 is a straight, tubular member. The supply mechanism 23 is positioned on the upper part of the surface 25, parallel to the Z direction. The supply mechanism 23 is positioned such that the opening of the tube faces the surface 25, and is closer to the rotation axis J than the irradiation position I when viewed from the Z direction. The supply mechanism 23 corresponds to one embodiment of the liquid raw material supply mechanism according to this technology.

[0050] In this example, the circulation mechanism 24 is a tubular member including a tank section. One end of the pipe is connected to the supply mechanism 23, and the other end is a communication hole 35 that communicates with the recess 30 of the cover member 21. In this example, only one communication hole 35 is configured, but the pipe of the circulation mechanism 24 may branch, and multiple communication holes 35 may be configured on the recess 30.

[0051] It is also possible to consider, for example, a part of the tubing of the circulation mechanism 24 as the supply mechanism 23. In other words, the classification of the supply mechanism 23 and the circulation mechanism 24 in this example is merely an example and does not limit which parts are considered to be the supply mechanism 23 and which parts are considered to be the circulation mechanism 24. Nor are their specific shapes limited.

[0052] A supply source (not shown) for the liquid raw material 31 is connected to the supply mechanism 23. This supply source has a pump or the like, and when the pump or the like is driven, the liquid raw material 31 is supplied to the supply mechanism 23, causing the liquid raw material 31 to flow out directly below the supply mechanism 23 as shown in Figure 2 and reach the surface 25. Figure 2 shows the supply position S of the liquid raw material 31. The supply position S is the position where the liquid raw material 31 flowing out of the supply mechanism 23 first adheres to the surface 25.

[0053] [Supply Position] Figure 3 is a schematic diagram showing the relationship between the irradiation position I and the supply position S. Figure 3 shows the surface 25 of the rotating body 20 as viewed from the positive side in the Z direction. The irradiation position I and the supply position S are indicated by black circles. As shown in this figure, the supply position S is located downstream of the irradiation position I in a clockwise direction. That is, as seen in Figure 2, the supply position S is located further back in the plane of the paper than the irradiation position I.

[0054] The supply mechanism 23 is positioned closer to the rotation axis J than to the irradiation position I. Therefore, the supply position S is also located closer to the rotation axis J than to the irradiation position I. In other words, in Figure 3, the supply position S is located inside a circle (shown by a dashed line) with the rotation axis J as its center and a diameter equal to the distance between the irradiation position I and the rotation axis J.

[0055] Note that the supply position S being closer to the rotation axis J than the irradiation position I includes both cases where the supply position S is at the same position as the rotation axis J and cases where it is at a different position. In this example, the supply position S is at a different position from the rotation axis J.

[0056] The specific location of the supply position S is not limited, provided that it is positioned inside the irradiation position I. For example, the supply position S may be positioned slightly upstream of the irradiation position I, or the angular positions of the supply position S and the irradiation position I may be the same. The supply position S may also be located to the right of the rotation axis J. Furthermore, the radial distance between the rotation axis J and the supply position S may be arbitrary.

[0057] Figures 2 and 3 show the liquid raw material 31 adhering to the surface 25 in gray. As the rotating body 20 rotates, the liquid raw material 31 adhering to the supply position S then moves clockwise as the rotating body 20 rotates, and also moves outward due to centrifugal force.

[0058] As a result, as shown in Figure 3, the liquid raw material 31 adheres to the surface 25 in a ring shape. In this example, for the sake of easier understanding of the figure, the inner boundary 33, which is the inner boundary of the liquid raw material 31, is shown as a perfect circle. However, in reality, as you move away from the supply position S in a clockwise direction, the inner boundary 33 expands outward.

[0059] When the energy beam EB is irradiated to the irradiation position I, the liquid raw material 31 attached to the surface 25 is excited, generating plasma P, and radiation R is emitted as shown in Figure 2. Although the liquid raw material 31 at the irradiation position I is instantaneously lost due to irradiation, new liquid raw material 31 is immediately supplied to the irradiation position I by the rotation of the rotating body 20 and centrifugal force. Therefore, a constant film thickness is always maintained at the irradiation position I, and there is no shortage of liquid raw material 31.

[0060] The rotation speed of the rotating body 20 may be set arbitrarily. For example, the faster the rotation speed, the smaller the film thickness becomes, and the degree of expansion of the inner boundary 33 also becomes more pronounced. Therefore, the rotation speed may be set to an appropriate value so that the film thickness is at an appropriate level. In addition, if the energy beam EB is emitted as a pulse wave, its frequency may also be taken into consideration.

[0061] [Circulation Mechanism] The circulation mechanism 24 supplies the liquid raw material 31 captured by the cover member 21 to the supply mechanism 23. As shown in Figure 2, the liquid raw material 31 that reaches the outer circumference of the surface 25 leaves the surface 25, but at this time it loses the normal force and surface tension of the surface 25 and scatters outwards toward the outside of the rotation while spreading vertically up and down.

[0062] The scattered liquid raw material 31 is captured by the recess 30 of the cover member 21. In other words, the recess 30 functions as a raw material receiver. The liquid raw material 31 flows along the recess 30 and into the communication hole 35. The circulation mechanism 24 has a pump (not shown), and when the pump is driven, the liquid raw material 31 that has flowed in from the communication hole 35 is transported to the supply mechanism 23 (arrow in Figure 2). In this way, the liquid raw material 31 is supplied to the supply mechanism 23.

[0063] Furthermore, there are no limitations on the specific methods for recovering and circulating the scattered liquid raw material 31. Typically, the liquid raw material 31 circulated by the circulation mechanism 24 is used for generating plasma P, but as plasma P is generated, the amount of liquid raw material 31 gradually decreases. Therefore, to compensate for the shortage, unused liquid raw material 31 can be supplied from the supply source of the supply mechanism 23. Of course, the circulation mechanism 24 may not be used at all, and unused liquid raw material 31 may always be supplied, with any unused liquid raw material 31 being immediately discarded.

[0064] In the plasma generation mechanism 106 according to this embodiment, the liquid raw material 31 is supplied to a supply position S on the rotating body 20, which is a generally flat plate. Furthermore, when viewed from the direction of the extension of the rotation axis J of the rotating body 20, the supply position S is located closer to the rotation axis J than to the irradiation position I of the energy beam EB. This makes it possible to stably emit radiation R.

[0065] For example, in an EUV light source device in which a rotating body is immersed in a bath containing liquid raw materials, one way to improve performance is to increase the repetition frequency of the incident laser. However, increasing the frequency narrows the distance between the area irradiated with the laser and the next area irradiated with the laser, causing energy to accumulate at the irradiated area and resulting in high temperatures.

[0066] If the rotation speed of the rotating body is slow, it takes time for the hot parts to be immersed in the liquid raw material again, so immediate cooling does not occur, and the rotating body can be damaged by heat. Therefore, when increasing the frequency, the rotation speed of the rotating body must also be increased.

[0067] However, increasing the rotation speed also increases the amount of liquid material that is stirred up from the bathtub. As a result, the liquid material adheres to other mechanisms such as the laser entrance window and the EUV output port, interfering with stable EUV emission.

[0068] Furthermore, in configurations where film thickness is adjusted using a skimmer, the skimmer's support structure is made elastic to track fluctuations in the liquid film. However, at high rotation speeds, such mechanical tracking becomes impossible, resulting in unstable light emission. In addition, contact between the skimmer and the rotating body can cause a jam, potentially leading to an emergency shutdown of the light source device itself.

[0069] In this technology, the rotation of the rotating body 20 and centrifugal force continuously generate a flow of liquid raw material 31 from the supply position S through the irradiation position I to the outside, so that the irradiation position I is always cooled. This makes it possible to suppress damage to the rotating body 20 due to heat.

[0070] Furthermore, since the film thickness can be changed simply by changing the rotation speed of the rotating body 20, it is possible to adjust the film thickness more easily and with greater precision compared to using a skimmer or the like. Also, since a skimmer is not required in the first place, the above-mentioned stacking cannot occur. As a result, stable light emission is achieved.

[0071] Furthermore, since the rotating body 20 is not immersed in the liquid raw material 31, contamination of other mechanisms by splashes is also suppressed.

[0072] Furthermore, in this technology, the supply position S is located at a different position from the rotation axis J when viewed from the direction of extension of the rotation axis J. Depending on the arrangement of other mechanisms and the required film thickness, such a configuration may be useful.

[0073] Furthermore, in this technology, the rotating body 20 is surrounded by the cover member 21. This prevents the liquid raw material 31 that has left the surface 25 and scattered from adhering to external mechanisms.

[0074] Furthermore, in this technology, the liquid raw material 31 captured by the cover member 21 is supplied to the supply mechanism 23 by the circulation mechanism 24. As a result, the liquid raw material 31 is reused, reducing the operating cost of the light source device 100. In addition, the labor involved in disposing of the liquid raw material 31 is reduced.

[0075] Furthermore, in this technology, the irradiation position I is located on the rotating body 20. As a result, the energy beam EB is irradiated onto the liquid raw material 31, which has been appropriately adjusted in film thickness, thereby achieving stable light emission.

[0076] Furthermore, in this technology, the rotation axis J is parallel to the vertical direction. This ensures uniform effects from gravity, thereby stabilizing the film thickness. Depending on the arrangement of other mechanisms, this configuration may be more advantageous than cases where the rotation axis J is parallel to the horizontal direction.

[0077] <Other Embodiments> This technology is not limited to the embodiments described above, and various other embodiments can be realized.

[0078] [Variations in Supply Position] Figure 4 is a schematic diagram showing examples of variations in the supply position S. In this example, when viewed from the Z direction, the supply position S is in the same position as the rotation axis J. That is, the supply mechanism 23 is also located on the rotation axis J. Note that "same position" includes not only perfectly identical positions but also states where the rotation axis J and the supply position S are slightly misaligned. In this example, the liquid raw material 31 flows out toward the center of the surface 25, and the liquid raw material 31 spreads and adheres to the entire surface 25.

[0079] If the supply mechanism 23 is close to the irradiation position I, the supply mechanism 23 may block the energy beam EB or radiation R. In this embodiment, since the supply position S and the rotation axis J are at the same position, this problem is suppressed. Also, because the supply position S is located at the center of rotation, the liquid raw material 31 tends to accumulate at the supply position S. As a result, the supply position S functions as a buffer, and the liquid raw material 31 adheres stably to the entire surface 25. Therefore, even more stable light emission is achieved.

[0080] To further improve its function as a buffer, a recess may be provided in the center of the surface 25. Similarly, even when the supply position S is at a different position from the rotation axis J, as shown in Figure 2, a recess may be provided on the surface 25 at a position corresponding to the supply position S. However, in the case of Figure 2, it becomes necessary to provide a ring-shaped recess, so Figure 4 is simpler.

[0081] [Variations in Irradiation Position] Figure 5 is a schematic diagram showing examples of variations in irradiation position I. In this example, irradiation position I is not located on the rotating body 20. Specifically, when viewed from the Z direction, irradiation position I is located between the rotating body 20 and the cover member 21. At irradiation position I, the liquid raw material 31 is slightly spread out, but plasma P is generated by irradiation, as in other configuration examples.

[0082] In this example, since irradiating with the energy beam EB from the upper left of the diagram would be blocked by the cover member 21, irradiation is performed from the upper right. However, irradiation from the upper left is also possible if it is not blocked by the cover member 21.

[0083] During irradiation, debris D is generated from the plasma P along with radiation R. In examples such as Figure 2, a rotating body 20 is present, so the debris D is scattered above the irradiation position I (not shown). On the other hand, in this example, the rotating body 20 is not present at the irradiation position I, and pressure is generated by the vaporization of the liquid raw material 31, so most of the debris D is scattered downwards.

[0084] This reduces the amount of debris D directed towards the radiation extraction direction (upward), preventing contamination of the optical system that processes the radiation R. Furthermore, since the irradiation position I is not located on the rotating body 20, thermal damage to the rotating body 20 can be suppressed.

[0085] Debris D scattered downwards is stored on the bottom surface 37 of the cover member 21 (the upper surface of the bottom portion 27). Therefore, the bottom portion 27 is positioned on the negative side of the Z direction, which is opposite to the positive side of the Z direction, which is the incident side of the energy beam EB, with respect to the irradiation position I, and functions as a container for capturing debris D scattered from the irradiation position I.

[0086] A drain is provided on the bottom surface 37. The drain is a mechanism for collecting debris D, and for example, a pipe or groove is provided to serve as a flow path for the debris D. Furthermore, a communication hole 38 is provided near the bottom surface 27 on the side portion 28 of the cover member 21, which communicates with the circulation mechanism 24. Debris D accumulated on the bottom surface 37 reaches the communication hole 38 via the drain and flows into the inside of the circulation mechanism 24 from the communication hole 38.

[0087] As a result, debris D is supplied to the supply mechanism 23 and reused. Debris D is transported by pumps, etc., of the circulation mechanism 24, but since debris D flows continuously into the bottom surface 37, it may be possible to realize the circulation mechanism 24 without the need for pumps, etc., due to the propulsion force of the debris D.

[0088] The debris D is captured by the bottom portion 27, which suppresses the scattering of debris D to the outside even in a configuration where there is no irradiation position I on the rotating body 20. Furthermore, in this example, the captured debris D is reused, further reducing the operating cost of the light source device 100. However, the debris D may be discarded without being reused.

[0089] [Variations of the Rotating Body] Figure 6 is a schematic diagram showing an example of a variation of the rotating body 20. In this example, the shaft member 22 is connected to the upper side of the rotating body 20, resulting in an inverted state. Of the surfaces of the rotating body 20, the surface 25 where the illumination position I is located is the vertically downward surface, and the back surface 26 is the upper surface.

[0090] The cover member 21 is also arranged in an inverted bowl shape as shown in Figure 2, etc., but has a bottom 40 on its lower side that is different from the original bottom 27. The upper surface 41 of the bottom 40 is parallel to the XY plane. The rotating body 20 and the cover member 21 are arranged such that the surface 25 of the rotating body 20 and the upper surface 41 of the bottom 40 are spaced apart in the Z direction.

[0091] A through-hole 42 is provided in the center of the bottom portion 40 for the supply mechanism 23 to pass through. An opening 43 is also provided in the bottom portion 40 for the energy beam EB to enter. The opening 43 is located above the rotating body 20.

[0092] When the liquid raw material 31 is supplied from the supply mechanism 23 (arrow in the figure), the liquid raw material 31 enters the space between the surface 25 and the upper surface 41. The liquid raw material 31 flows outward due to centrifugal force, passes over the top of the opening 43, and continues to flow outward. At this time, since the centrifugal force is sufficiently large compared to gravity, the liquid raw material 31 passing over the top of the opening 43 hardly falls.

[0093] In order to achieve this flow, a certain degree of affinity between the liquid raw material 31 and the surface 25, and between the liquid raw material 31 and the upper surface 41 are necessary. Therefore, the surface 25 and the upper surface 41 are made of appropriate materials.

[0094] Under these conditions, by injecting the energy beam EB into the aperture 43 from below, plasma P is generated and radiation R is emitted downwards. In this example, as in Figure 2, the irradiation position I is a position on the rotating body 20. In this embodiment, since the film thickness at irradiation position I is determined according to the size of the gap between the surface 25 and the upper surface 41, it is possible to adjust the film thickness with even greater precision. Furthermore, if other mechanisms are located on the upper side and it is not possible to inject the energy beam EB from above or extract radiation R, a configuration like this example is useful.

[0095] Furthermore, the cover member 21 has a storage 44 on the outside of the side portion 28. The liquid raw material 31 that passes through the opening 43 is temporarily stored in the storage 44 and then discharged. By providing the storage 44, it is prevented that the liquid raw material 31 will overflow from the gap between the rotating body 20 and the side portion 28. The discharged liquid raw material 31 may be recycled to the supply mechanism 23 and reused.

[0096] Figure 7 is a schematic diagram showing an example of a variation of the rotating body 20. In this example, the opening 43 is an opening for the passage of debris D, and a debris receiver 45 is connected to the lower side of the opening 43. In addition, an opening 46 is provided at the upper bottom 27 of the cover member 21 for the incidence of the energy beam EB. Both openings 43 and 46 are provided in positions where the rotating body 20 is not present.

[0097] Under these conditions, by injecting the energy beam EB into the aperture 46 from above, radiation R is extracted from the aperture 46. In other words, in this example, as in Figure 4, the irradiation position I is not a position on the rotating body 20. Also, the debris D is emitted downwards from the aperture 43 and is captured by the debris receiver 45.

[0098] In this example, similar to Figure 4, it is possible to reduce the debris D directed towards the radiation extraction direction (upward) while suppressing damage to the rotating body 20. Also, similar to Figure 7, it is possible to precisely adjust the film thickness. Furthermore, the debris D captured by the debris receiver 45 may be collected in a drain (not shown) and reused.

[0099] Figure 8 is a schematic diagram showing an example of a variation of the rotating body 20. In this example, the rotating body 20 and the cover member 48 are lying on their sides. Figure 8 is a cross-sectional view when these are cut by a plane parallel to the YZ plane and containing the axis of rotation J.

[0100] The rotation axis J of the rotating body 20 is parallel to the horizontal direction (in this example, the Y direction). The rotating body 20 is positioned in the internal space N of the cover member 48. The supply mechanism 23 passes through the center of the positive side portion 49 in the Y direction of the cover member 48, and an opening 50 for the energy beam EB to enter is provided below the center.

[0101] When the liquid raw material 31 is supplied from the supply mechanism 23, the liquid raw material 31 moves outward along the surface 25 of the rotating body 20 due to centrifugal force. Since the centrifugal force is sufficiently large compared to gravity, the liquid raw material 31 also spreads upward from the center. Under these conditions, when the energy beam EB is incident on the aperture 50 from the positive side in the Y direction, radiation R is emitted from the aperture 50.

[0102] Furthermore, the liquid raw material 31 that flows below the opening 50 is stored in the lower part of the internal space N. As a result, the lower part of the rotating body 20 is immersed in the liquid raw material 31. In this example, both the supply of liquid raw material 31 by the supply mechanism 23 and the supply of liquid raw material 31 by immersion are performed, so the liquid raw material 31 is supplied even more stably. Note that the liquid raw material 31 that flows to the lower side is immediately discarded, and the rotating body 20 does not need to be immersed.

[0103] [Circulation by Cover Member] Figures 9 and 10 are schematic diagrams showing an example configuration in which the cover member 21 has a circulation mechanism 24. In Figure 9, a part of the internal mechanism of the cover member 21 and the rotating body 20 arranged in the internal space N of the cover member 21 are shown with solid lines without distinction from the external shape. Figure 10 is a cross-sectional view along line A-A in Figure 9, showing only roughly the upper half. Note that the rotation axis J and direction of rotation are omitted for clarity.

[0104] As shown in Figure 9, liquid raw material 31 is stored in the lower part of the internal space N, similar to the example in Figure 8. The lower part of the rotating body 20 is immersed in the stored liquid raw material 31. Unlike the example in Figure 8, the cover member 21 has an opening 50 on the left side when viewed from the positive side in the Y direction.

[0105] When focusing on the portion of the internal space N that is on the positive side in the Y direction relative to the rotating body 20, the majority of it is a single layer of internal space N sandwiched between the side portion 49 and the rotating body 20. １ This is the case. However, as shown in Figure 9, a narrow, two-layered space exists only above the center of the rotating body 20. Figure 10 is a cross-sectional view of the portion where this two-layered space exists. Specifically, it is the internal space N sandwiched between the side portion 49 and the inner wall 52. ２and an internal space N sandwiched between the inner wall 52 and the rotating body 20 ３ are present. The internal space N ２ communicates with the internal space N at the position of the rotation axis J ３ .

[0106] In FIG. 10, the flow of the liquid raw material 31 is indicated by arrows. When the rotating body 20 starts to rotate, the liquid raw material 31 stored in the lower portion of the internal space N adheres to the entire surface of the rotating body 20. The adhered liquid raw material 31 is wound up by rotation, and enters the internal space N from the upper portion ２ (dashed arrow). The liquid raw material 31 flows downward through the internal space N ２ , and enters the internal space N at the position of the rotation axis J ３ . As a result, the liquid raw material 31 adheres to the center of the surface 25 of the rotating body 20.

[0107] A part of the adhered liquid raw material 31 continues to adhere to the surface 25 and flows upward through the internal space N by centrifugal force ３ , and enters the internal space N again from the upper portion ２ . In this way, the state in which the liquid raw material 31 that has entered the internal space N from the upper portion is returned to the center of the surface 25 continues ２ .

[0108] That is, portions of the side portion 49 and the inner wall 52 near the rotation axis J function as the supply mechanism 23 according to the present technology. Of these, the upper portion of the rotation axis J functions as the circulation mechanism 24 according to the present technology. In FIG. 10, these are schematically illustrated by dashed frames.

[0109] The liquid raw material 31 adhering to the surface 25 eventually leaves the surface 25. Further, when the rotation speed of the rotating body 20 increases, the liquid raw material 31 is vigorously wound up. In this example, a part of such liquid raw material 31 enters the internal space N ２ and is returned to the surface 25, so that the liquid raw material 31 is supplied more stably.

[0110] The liquid raw material 31 that has entered the internal space N ２ is not returned to the surface 25, and re-enters the internal space N １It may be stored on the lower side. Also, if the rotation speed increases, the film thickness decreases, and it may become impossible to secure the film thickness necessary for stable light emission. In this case, a separate supply source may be connected to the supply mechanism 23 of this example, and additional liquid raw material 31 may be supplied.

[0111] In this example, a recess 53 is provided in the center of the shaft member 22, and the tip of the supply mechanism 23 is inserted into the recess 53. This allows the recess 53 to function as a buffer, reducing the amount of liquid raw material 31 flowing downwards. In this example, the shaft member 22 passes through the center of the rotating body 20, but if the shaft member 22 does not pass through, the recess 53 may be configured in the center of the rotating body 20. Also, if the rotation speed of the rotating body is fast, the transport speed of the liquid raw material 31 increases, resulting in faster circulation. Consequently, the recess 53 in the center of the shaft member 22 or the center of the rotating body 20 may become unnecessary. Therefore, the presence of the recess 53 depends on the rotation speed.

[0112] Each internal space N １ ~N ３ The specific shape is not limited. Also, there are multiple internal spaces N ２ These may be configured such that each is in communication with the center of the surface 25.

[0113] [Variations in the Shape of the Rotating Body] Figure 11 is a schematic diagram showing examples of variations in the shape of the rotating body 20. In this example, the rotating body 20 has a shape that is concave toward the surface 25. Since this shape is also generally flat, it is included in "generally flat". In addition, the rotating body 20 may have any shape that is generally flat.

[0114] [Types of liquid raw materials] The specific type of liquid raw material 31 is not limited. For example, not only liquid raw materials 31 that are completely liquid, but also liquid raw materials 31 in which solids that are in the process of melting are mixed in the liquid may be used.

[0115] [Application to other devices] In this example, we have described the case in which this technology is applied to an LPP light source device, but it is not limited to this, and this technology may also be applied to DPP or LDP light source devices.

[0116] It is also possible to combine at least two of the feature features of this technology described above. Furthermore, the various effects described above are merely examples and are not limiting, and other effects may also be exhibited.

[0117] D...Debris EB...Energy beam I...Irradiation position J...Rotation axis N, N １ , N ２ , N ３ …Internal space R…Radiation S…Supply location 20…Rotating body 21, 48…Cover member 23…Supply mechanism 24…Circulation mechanism 25…Surface 27…Bottom 30…Recess 31…Liquid raw material 48…Cover member 49…Side 50…Opening 52…Inner wall 53…Recess 100…Light source device 106…Plasma generation mechanism

Claims

1. A light-emitting unit that generates radiation by plasmaizing a liquid raw material by irradiation with an energy beam, comprising: a rotating body having a plate shape and being rotatable about a predetermined rotation axis; and a liquid raw material supply mechanism that supplies the liquid raw material to a supply position which is a position on the rotating body, wherein, when viewed from the direction of extension of the rotation axis, the supply position is located closer to the rotation axis than the irradiation position of the energy beam.

2. A light-emitting unit according to claim 1, wherein the supply position is located at the same position as the rotation axis when viewed from the extending direction of the rotation axis.

3. A light-emitting unit according to claim 1, wherein the supply position is located at a position different from the rotation axis when viewed from the extending direction of the rotation axis.

4. A light-emitting unit according to claim 1 or 2, further comprising a cover member surrounding the rotating body.

5. A light-emitting unit according to claim 4, further comprising a circulation mechanism for supplying the liquid raw material captured by the cover member to the liquid raw material supply mechanism.

6. A light-emitting unit according to claim 1 or 2, wherein the irradiation position is a position on the rotating body.

7. A light-emitting unit according to claim 1 or 2, wherein the irradiation position is a position other than the position on the rotating body.

8. A light-emitting unit according to claim 7, further comprising a container positioned on the opposite side of the irradiation position from the incident side of the energy beam with respect to the irradiation position, for capturing debris scattered from the irradiation position.

9. A light-emitting unit according to claim 8, further comprising a circulation mechanism for supplying the debris captured by the container to the liquid raw material supply mechanism.

10. A light-emitting unit according to claim 1 or 2, wherein the rotation axis is parallel to the vertical direction.

11. A light-emitting unit according to claim 1 or 2, wherein the rotating body is a generally flat plate.

Images