Light source device

Abstract

The purpose of the present technology is to provide a light source device in which it is possible to efficiently remove low-speed debris.　A light source device according to one embodiment of the present technology generates radiation by converting a raw material to plasma through injection of energy, the light source device comprising a chamber, a rotating body (20), an energy source, and a plurality of foils (25a to 25g). The rotating body (20) is accommodated in the chamber, is capable of rotating about a prescribed rotation axis, and has a region to which the raw material adheres. The energy source injects the energy into the region and generates the plasma at the position where the energy is injected. The plurality of foils (25a to 25g) have a planar shape. Each of the plurality of foils (25a to 25g) is disposed such that the end thereof on the side close to the injection position faces the injection position and intersects the movement direction of the rotating body (20) at the injection position.

Description

Light source device

[0001] The present technology relates to a light source device that generates radiation such as X-rays and extreme ultraviolet light.

[0002] Among X-rays, extreme ultraviolet light (hereinafter also referred to as "EUV (Extreme Ultra Violet) light") has been used as exposure light in recent years. The substrate of a mask for EUV lithography is configured by patterning a material that absorbs radiation for EUV lithography on a multilayer film (for example, molybdenum and silicon) for reflecting EUV light.

[0003] The size of unacceptable defects in EUV masks has been significantly reduced and detection has become difficult. Therefore, for the inspection of EUV masks, inspection using radiation with a wavelength that matches the working wavelength of lithography, called actinic inspection, is performed.

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

[0005] The DPP light source device applies a high voltage between electrodes to which a gaseous plasma raw material (discharge gas) containing an EUV radiation species is supplied, generates a high-density high-temperature plasma by discharge, and utilizes the extreme ultraviolet light emitted therefrom.

[0006] The LDP light source device is an improved version of the DPP light source device. For example, a liquid high-temperature plasma raw material (for example, Sn (tin), Li (lithium), etc.) containing an EUV radiation species is supplied to the surface of an electrode (discharge electrode) that generates discharge, the raw material is vaporized by irradiating it with a laser beam, and then a high-temperature plasma is generated 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 technology that can efficiently remove relatively slow-moving debris generated by the irradiation of an energy beam.

[0012] In view of the above circumstances, the object of the present invention is to provide a light source device that enables the efficient removal of slow-moving debris.

[0013] To achieve the above objective, a light source device according to one embodiment of this technology is a light source device that generates radiation by plasmaizing a raw material by injecting energy, and comprises a chamber, a rotating body, an energy source, and a plurality of foils. The rotating body is housed in the chamber, is rotatable about a predetermined axis of rotation, and has a region to which the raw material is attached. The energy source injects the energy into the region and generates the plasma at the energy injection position. The plurality of foils have a planar shape. Each of the plurality of foils is arranged so that the end closest to the injection position faces the injection position and intersects with the direction of movement of the rotating body at the injection position.

[0014] In this light source device, each of the multiple foils is positioned so that the end closest to the injection point faces the injection point and intersects with the direction of movement of the rotating body at the injection point. This makes it possible to efficiently remove slow-moving debris.

[0015] Each of the plurality of foils may be arranged such that the ends furthest from the injection position are aligned at the same distance in the direction of movement.

[0016] Each of the plurality of foils may be arranged along the direction of emission of the radiation.

[0017] The light source device may include a housing having an internal space through which the radiation passes and through which the plurality of foils are arranged. In this case, each of the plurality of foils has a single, unseparated surface shape, and the internal space may be separated by this single surface shape. In this case, the plurality of foils and the housing can serve as debris reduction members.

[0018] Each of the plurality of foils may have a shape obtained by dividing a single, unseparated surface shape with a plane perpendicular to the radiation emission axis.

[0019] Each of the plurality of foils may have the same length L (m) in the direction of the radiation emission axis. In this case, when the moving speed of the rotating body at the injection position is V (m / s) and the spacing is I (m), L ≥ 70I / V may be used.

[0020] The distance between the ends of each of the plurality of foils furthest from the injection position in the direction of movement may be 5.3 mm or less.

[0021] Each of the plurality of foils may consist of a plurality of first foils having the same length in the direction of the radiation emission axis, and a plurality of second foils having a length in the direction of the emission axis that is shorter than the length of the first foils. In this case, the first foil and

[0022] The light source device may further include a gas introduction unit that introduces gas to a position closer to the injection position than the plurality of foils.

[0023] Each of the aforementioned foils may have a planar shape.

[0024] According to the present invention, it is possible to efficiently remove slow-moving debris. The effects described herein are not necessarily limited, and any of the effects described herein may also be present.

[0025] This is a schematic diagram showing an example configuration of the light source device according to this embodiment. This is a front view showing an example configuration of the debris reduction member. This is a perspective view showing an example configuration of the debris reduction member. This is a perspective cross-sectional view showing an example configuration of the debris reduction member. This is a perspective cross-sectional view showing an example configuration of the debris reduction member. This is a schematic diagram showing the direction of movement. This is a schematic diagram showing the direction of movement. This is a schematic diagram showing the typical length of the foil. This is a schematic diagram showing a divided foil shape. This is a schematic diagram showing an example configuration of an additional foil.

[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 plasma material 101 by irradiating (injecting) an energy beam EB into the plasma material 101 to generate plasma P, and extracts radiation R emitted from the plasma P to use as a light source. Radiation R is EUV light, X-rays, or other electromagnetic waves. The energy beam EB corresponds to one embodiment of energy.

[0027] The plasma raw material 101 is a molten metal or alloy, for example, 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. The plasma raw material 101 corresponds to one embodiment of the raw material.

[0028] Figure 1 shows a schematic cross-section of the light source device 100, viewed from vertically above, when the device is cut horizontally at a predetermined height from the installation surface. In Figure 1, to facilitate understanding of the configuration and operation of the light source device 100, the cross-sectional view is omitted where it is not necessary to explain the configuration of the cross-section. Hereafter, the X and Y directions may be referred to as horizontal directions, and the Z direction as vertical directions. Of course, the application of this technology is not limited to the orientation in which the light source device 100 is used.

[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. The vacuum chamber 103 corresponds to one embodiment of the chamber.

[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 into the inside of the housing 102 along the incident axis IA. An electron beam or laser light can be used as the energy beam EB. The beam source 108 represents one embodiment of the energy source.

[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] A user device, such as a mask inspection device, is connected to the end of the ejection chamber 105 opposite the plasma generation mechanism 106. In the example shown in Figure 1, an application chamber 110 is connected as a chamber that forms part of the user device. The pressure inside the application chamber 110 may be atmospheric pressure. The inside of the application chamber 110 may also be purged by introducing gas (for example, an inert gas) from a gas injection passage as needed, and exhausted by an exhaust means not shown. Between the application chamber 110 and the ejection chamber 105, a filter membrane 111 or an opening is provided to physically separate the region where plasma P is generated from the application chamber 110.

[0035] The vacuum chamber 103 is provided with an entrance window 114. The entrance window 114 is positioned on the entrance axis IA of the energy beam EB, aligned with the entrance hole 102b. An exhaust pump 117 is also connected to the vacuum chamber 103.

[0036] Furthermore, as shown in Figure 1, the exit chamber 105 and the injection chamber 104 are provided with gas injection passages 116a and 116b, respectively, and gas is supplied to the interiors of the exit chamber 105 and the injection chamber 104 from a gas supply device (not shown). The exit chamber 105 is supplied with a gas that has high transmittance to radiation R, such as argon or helium. The injection chamber 104 is supplied with a gas that has high transmittance to energy beam EB, such as argon or helium.

[0037] The plasma generation mechanism 106 is a mechanism that generates plasma P and emits radiation R. The plasma generation mechanism 106 is housed in a vacuum chamber 103. As shown in Figure 1, the plasma generation mechanism 106 has a rotating body 20.

[0038] An energy beam EB is incident on the rotating body 20. The rotating body 20 is positioned such that the irradiation position I of the energy beam EB is located at the intersection of the incidence axis IA and the emission axis EA. The irradiation position I corresponds to one embodiment of the energy injection position.

[0039] A shaft member 72 is connected to the center of the back surface (the negative side of the Y-axis) of the rotating body 20. The shaft member 72 is positioned to penetrate the vacuum chamber 103 and the housing 102. A motor 71 is positioned outside the housing 102, and the motor 71 is connected to the end of the shaft member 72 that is not connected to the rotating body 20.

[0040] When the motor 71 is driven, the shaft member 72 and the rotating body 20 rotate together. The direction of these rotations is indicated by arrows in Figure 1. In this example, the rotating body 20 rotates counterclockwise when viewed from the positive side of the Y-axis, but it may also rotate clockwise. In this example, a mechanical seal 73 is provided at the portion of the shaft member 72 that penetrates the vacuum chamber 103. This ensures smooth rotation while maintaining the airtightness of the vacuum chamber 103.

[0041] Furthermore, the plasma generation mechanism 106 has a raw material container 21. Plasma raw material 101 is stored in the raw material container 21, and the lower side of the rotating body 20 is immersed in the stored plasma raw material 101.

[0042] As the rotating body 20 rotates, the plasma raw material 101 is lifted while adhering to the rotating body 20. As a result, the plasma raw material 101 is always adhering to the surface of the rotating body 20, and the plasma raw material 101 is supplied to the irradiation position I. Furthermore, the energy beam EB is irradiated (energy is injected) onto the adhering plasma raw material 101 by the beam source 108. This generates plasma P at the irradiation position I.

[0043] 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.

[0044] 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.

[0045] Further, in the present embodiment, a debris reduction member 22 is disposed between the irradiation position I and the emission chamber 105. In FIG. 1, the position where the debris reduction member 22 is disposed is schematically illustrated as a shaded rectangle.

[0046] [Debris Reduction Member] FIG. 2 is a front view showing a configuration example of the debris reduction member 22. FIG. 3 is a perspective view showing a configuration example of the debris reduction member 22. FIG. 4 is a perspective cross-sectional view showing a configuration example of the debris reduction member 22. In FIGS. 2 to 4, in addition to the debris reduction member 22, a rotating body 20 is illustrated. Further, in FIGS. 3 and 4, the incident axis IA of the energy beam EB and the emission axis EA of the radiation R are illustrated. Other mechanisms such as the raw material container 21 are not illustrated.

[0047] FIG. 2 is a view of the debris reduction member 22 as seen from the positive side of the Y axis. FIG. 3 is a view of the debris reduction member 22 as seen from the direction of arrow A in FIG. 2 (upper right side). In FIG. 3, in order to make the internal structure of the debris reduction member 22 easy to understand, only the housing 24 of the debris reduction member 22 is illustrated as a cross-sectional view taken by a plane parallel to the Y axis passing through line B - B in FIG. 2. Also, although the Z axis is illustrated slightly diagonally downward to the right, this means that the Z axis is inclined toward the front side of the paper surface with respect to the right side. Similarly, the X axis is also inclined toward the back side of the paper surface.

[0048] FIG. 4 is a view of the cross-section of the debris reduction member 22 taken by a plane parallel to the Y axis passing through line C - C in FIG. 2 as seen from the direction of arrow C in FIG. 2 (upper left side). In FIG. 4, for the rotating body 20, a normal view that is not a cross-sectional view is illustrated.

[0049] Hereinafter, in addition to the XYZ axes, there may be cases where explanations are made using the axis formed by line B - B as the B axis and the axis formed by line C - C as the C axis. The positive side of the B axis is the upper left side in FIG. 2, the right side in FIG. 3, and the front side in FIG. 4. The positive side of the C axis is the lower left side in FIG. 2, the back side in FIG. 3, and the right side in FIG. 4.

[0050] Figure 2 shows the axis of rotation G of the rotating body 20 with a black circle, and Figures 3 and 4 show it with a dashed line. Furthermore, the direction of rotation is indicated by an arrow. When viewed from the orientation in Figure 2, the rotating body 20 rotates counterclockwise, and when viewed from the orientations in Figures 3 and 4, it rotates so that the front side moves to the right and the back side moves to the left.

[0051] Hereinafter, the circular surface on the positive side of the Y-axis of the rotating body 20 will be referred to as the main surface 23. The main surface 23 corresponds to one embodiment of the region to which the raw material related to this technology is attached. At the irradiation position I, radiation R is emitted in all directions of the hemisphere, but if the rotating body 20 is not rotating, the most radiation R is emitted in the direction normal to the main surface 23. Therefore, the emission axis EA of radiation R is a straight line extending from the irradiation position I in the direction normal to the main surface 23. The emission axis EA is parallel to the Y-axis and coincides with the rotation axis G when viewed from the direction in Figure 4.

[0052] The debris reduction member 22 comprises a housing 24 and seven foils 25 (25a to 25g). The housing 24 is a tubular member with a truncated cone shape. The housing 24 may have other tubular shapes or shapes other than tubular shapes, as long as the technology is feasible.

[0053] The foil 25 is a component having a planar shape, and in this embodiment, it has a trapezoidal planar shape. However, it is not limited to this, and any shape with a small thickness may be included in the planar shape referred to in this technology. For example, within the scope that this technology is feasible, the foil 25 may have a planar shape of another shape, or it may have a planar shape that is partially curved.

[0054] The foil 25 is placed in the internal space S, which is the space enclosed by the cylindrical shape of the housing 24. The internal space S also has the shape of a frustocone. The internal space S is also the space through which radiation R passes. In this embodiment, seven foils 25 are placed, but any number of foils 25, two or more, may be placed. Furthermore, the specific arrangement of each foil 25 is not limited, and any arrangement can be taken within the range in which this technology can be realized. As for the material of the foil 25, for example, molybdenum, tungsten, tantalum, titanium alloy, stainless steel, alumina, silicon nitride, boron nitride, etc. can be used, but the specific material is not limited.

[0055] Figure 5 is a perspective cross-sectional view showing an example of the configuration of the debris reduction member 22. In this example, the debris reduction member 22 is positioned so as to be tilted with respect to the direction normal to the rotating body 23. In this example, as viewed from the orientation of Figure 5, the debris reduction member 22 is tilted to the left with respect to the direction normal to the rotating body 23, but it may also be tilted to the right.

[0056] [Foil Arrangement] The arrangement of the foils 25 will be explained in detail. In this embodiment, the foils 25 are arranged such that, when viewed from the direction shown in Figure 4, the cross-section of the foils 25 appears radially radiating from the irradiation position I. Hereafter, the foils 25 will be referred to as foils 25a, 25b, ..., 25g, starting from the one located on the left side of Figure 4. These are arranged symmetrically with respect to a plane that includes the emission axis EA and is parallel to the B axis. In particular, the central foil 25d is arranged to overlap with this plane. Figure 5 shows the optical axis EA' of the radiation R, which is the optical axis along the central foil 25d.

[0057] Each foil 25 is positioned so that its trapezoidal legs abut against the inner wall of the housing 24 (the surface facing the internal space S). Therefore, as shown in Figure 3, the relative widths of the foils 25 in the B direction are: foil 25d > foils 25c and 25e > foils 25b and 25f > foils 25a and 25g. Note that in Figure 3, foils 25e to 25g are hidden at the back of the paper and are therefore not visible.

[0058] More specifically, each of the foils 25 is positioned along the direction of emission of radiation R. That is, although the rays of radiation R are straight lines extending from the irradiation position I in any direction on the hemisphere, each of the foils 25 is aligned with, or overlaps with, at least one of these rays.

[0059] For example, the central foil 25d is aligned with the light ray emitted from the irradiation position I in the normal direction (which is the same as the emission axis EA). Note that if the number of foils 25 is even, there may be no foil 25 aligned with the light ray emitted in the normal direction. Furthermore, the other foils 25 are also aligned with the light ray at the center in direction B.

[0060] Typically, in Figure 4, if the straight line extending from the lower end of the foil 25 coincides with the irradiation position I, then the foil 25 will be aligned with at least one of the light rays. In this example, it can also be said that multiple foils 25 are arranged radially.

[0061] On the other hand, if, for example, the foil 25 is positioned parallel to the BC plane (XZ plane), this is not considered to be positioned along the direction of emission of radiation R. In addition, if the foil 25 is tilted from the state shown in Figure 4, it may no longer be positioned along the direction of emission of radiation R.

[0062] In Figure 4, each of the seven foils 25 is positioned so that the end closest to the irradiation position I (i.e., the lower end in Figure 4) faces the irradiation position I. Similarly, in Figure 5, the end closest to the irradiation position I also faces the irradiation position I. In other words, the fact that the ends face the irradiation position I does not only mean that the debris reduction member 22 is positioned directly in front of the irradiation position I.

[0063] Figures 6 and 7 are schematic diagrams showing the direction of movement. It can also be said that the foil 25 is positioned so as to intersect with the direction of movement of the rotating body 20 at the irradiation position I. "Direction of movement" refers to the direction in which a point on the rotating body 20 at the irradiation position I moves when the rotating body 20 rotates. In Figure 2, when the rotating body 20 rotates counterclockwise, the point moves to the positive side of the C-axis. Therefore, the positive side of the C-axis is the direction of movement. In Figure 2, the direction of movement is illustrated with an arrow.

[0064] As shown in Figure 6, this direction of movement can also be described as the direction of the tangent to the main surface 23 of the rotating body 20 at the upper left intersection of the straight line connecting the rotation axis G and the irradiation position I (corresponding to the line B-B in Figure 2) and the side of the rotating body 20, which is the direction of the positive C axis.

[0065] "Intersecting the direction of movement" means not being parallel to the direction of movement. In fact, none of the foils 25 are positioned parallel to the positive direction of the C-axis. Therefore, all of the foils 25 intersect the direction of movement.

[0066] In particular, foil 25d is positioned parallel to the BY plane, and the BY plane is perpendicular to the C axis. Therefore, it can also be said that foil 25d is perpendicular to the direction of movement. Note that if the number of foils 25 is even, there may be no foil 25 that is perpendicular to the direction of movement.

[0067] On the other hand, if the foil 25 is arranged parallel to the C-axis, for example, if it is arranged parallel to the CY plane, this is not considered to be arranged so as to intersect the direction of movement.

[0068] Figure 7 shows only the negative Y-axis ends of foils 25c, 25d, and 25e of foil 25. Figure 7 shows these foils as viewed from the negative Y-axis. The extension direction of the foil ends is along the B-axis, and the direction of movement is along the positive C-axis; therefore, the ends are perpendicular to the direction of movement. This is also true for the other foils 25.

[0069] Figure 8 is a schematic diagram showing the typical length of the foil 25. This figure shows a cross-section of only foils 25d and 25e of the foil 25, similar to that shown in Figure 4. In this embodiment, each of the foils 25 is arranged such that the ends furthest from the irradiation position I are aligned at the same distance in the direction of movement.

[0070] The foil 25 has an edge that is the rightmost and an edge that is the leftmost in Figure 8, with the edge furthest from the irradiation position I being the rightmost. As mentioned earlier, the direction of movement is in the C direction. That is, the rightmost foils 25 are lined up at the same interval (representative length) in the C direction. Hereafter, this representative length will be denoted as I (m). Since the foils 25 are arranged radially, the interval between the foils 25 gradually decreases from I (m) as you approach the irradiation position I from the rightmost foil.

[0071] In this embodiment, each of the foils 25 is configured to have the same length in the direction of the radiation emission axis EA. In this example, the direction of the emission axis EA corresponds to the Y direction. Hereinafter, this length will be denoted as L (m). Furthermore, the moving speed of the rotating body 20 at the irradiation position I will be denoted as V (m / s).

[0072] For the other foils 25 not shown in Figure 8, the characteristic length is similarly I (m), and the length in the Y direction is L (m). Note that since the foils 25 other than foil 25d are positioned diagonally with respect to the Y direction, the length of these foils 25 in the extending direction (diagonal direction) is slightly longer than L (m).

[0073] The inventor considered the relationship that I, L, and V, as defined in this way, must satisfy. If the rotating body 20 is not rotating, the debris will be released most in the direction normal to the main surface 23 of the rotating body 20. However, if the rotating body 20 is rotating, due to the effect of inertia, the direction of debris release is thought to be biased towards the direction of movement of the rotating body 20 at the irradiation position I.

[0074] Figures 4 and 5 schematically illustrate the direction of debris release using arrows. As shown, debris is released mostly in the direction of movement (the positive side of the C-axis). Note that the arrows in the figures are only schematic and may not correspond to the actual release state.

[0075] The main objective of this technology is to remove relatively slow-moving debris. Specifically, debris with a velocity of approximately 70 m / s or less in the Y direction is often difficult to remove even with other technologies, and it is desirable that this technology be able to remove debris of this velocity.

[0076] Focusing on the low-velocity debris released in the normal direction when the rotating body 20 is not rotating, this debris has a large mass and is therefore greatly affected by inertia when the rotating body 20 rotates. Accordingly, it can be assumed that this debris has the same velocity component V (m / s) as the rotating body 20 in the C direction. It also has a velocity component of approximately 70 (m / s) in the Y direction.

[0077] If debris enters from between foils 25d and 25e, and collides with foil 25e before exiting from the right edge of foils 25d and 25e, the debris will lose kinetic energy due to the collision and be removed.

[0078] In other words, if we consider the case where the debris enters from the upper end between foils 25d and 25e (the position marked with an "x" in Figure 8), then the time required for the debris to travel L (m) in the Y direction must be greater than or equal to the time required for the debris to travel I (m) in the C direction. Since the velocity of the debris in the Y direction is 70 (m / s), the time required to travel L (m) is L / 70 (s). Similarly, the time required to travel I (m) is I / V (s). Therefore, the condition becomes L / 70 ≥ I / V, and multiplying both sides by 70 gives L ≥ 70I / V.

[0079] Therefore, if this equation is satisfied, debris that entered from the position marked with an "x" will be removed. Similarly, if debris enters from any other position between foils 25d and 25e, it will also be removed. In this case, I in the equation will be a smaller value, resulting in a less stringent condition. Similarly, debris that enters between other foils 25 will also be removed.

[0080] As mentioned above, by installing a foil that satisfies the condition L ≥ 70 I / V, it is possible to remove debris with a velocity of 70 m / s or less, which is relatively difficult to remove, but it is also acceptable to install one that can remove faster debris. For example, if the goal is to remove debris with a velocity component up to 110 m / s, the condition L ≥ 110 I / V may be used, and if the goal is to remove debris with a velocity component up to 250 m / s, it is desirable to install a foil of a length that satisfies the condition L ≥ 250 I / V.

[0081] In reality, the debris is also affected by gravity. However, since the rotation of the rotating body 20 is sufficiently fast, the effect of gravity is extremely small compared to the effect of inertia. Therefore, the effect of gravity is ignored in the above calculation. Not limited to this, conditional equations that take the effect of gravity into account may also be used.

[0082] In Figure 4, the lengths of each foil 25d in the Y direction are slightly different, but even when the lengths differ slightly due to the design, this is still considered "same length" in this technology. In this case, the design may be such that the smallest length L satisfies the condition.

[0083] In the light source device 100 according to this embodiment, each of the multiple foils 25 is arranged such that the end closest to the irradiation position I faces the irradiation position I and intersects with the direction of movement of the rotating body 23 at the irradiation position I. This makes it possible to efficiently remove slow-moving debris.

[0084] In a light source device like the one in this embodiment, it is necessary to increase the opening angle of the radiation extraction port (corresponding to the housing 24 of this technology) in order to obtain more radiation. However, increasing the opening angle of the port allows a lot of debris to enter the port. The debris that enters will have an adverse effect on structures installed downstream of the port.

[0085] Light source devices are equipped with optical systems that can handle radiation specifically according to its wavelength. To utilize radiation more effectively, these optical systems need to be brought as close as possible to the irradiation position. However, this can lead to sputtering, where the reflective surface of optical components is abraded by the aforementioned debris; deposition, where debris accumulates on the reflective surface; or implantation, where debris is driven deep into the reflective surface. These can impair the function of the optical system and reduce the overall performance of the light source device. Therefore, some measures are needed to protect the optical system and other structures from debris.

[0086] For example, one could consider increasing the rotational speed of the rotating body to make it more difficult for debris to enter the port due to the effect of inertia. However, considering the wear and tear on mechanical parts such as bearings, it is difficult to increase the rotational speed to a degree that sufficiently prevents debris from entering.

[0087] Another possible method is to install a rotating foil trap. This method physically collides the debris with the rotating foil, resulting in a high removal effect regardless of the debris's mass or size. However, since the motor for rotating the foil is installed in the path of the radiation, the motor can obstruct the radiation's propagation, leading to a decrease in radiation output. Furthermore, there may be structural constraints on the placement of the motor itself.

[0088] Another possible method for removing debris is to introduce gas into the space between the irradiation position and the optical system, thereby creating a localized high-pressure space. In this high-pressure space, the debris collides with gas particles, and the debris, having lost kinetic energy due to the collisions, is removed from the optical path along the gas flow.

[0089] This method uses a gas that is transparent to radiation, so radiation attenuation is unlikely to occur. Also, as mentioned above, it does not require a motor, so the propagation of radiation is less likely to be hindered. However, slow-moving debris has a large mass and cannot be sufficiently held back by the gas. Therefore, the problem of not being able to completely remove slow-moving debris remains.

[0090] In contrast to these, this technology arranges multiple foils 25 so as to intersect with the direction of movement of the rotating body 20 at the irradiation position I, thereby enabling debris removal by utilizing the bias in the ejection direction of low-speed debris.

[0091] Furthermore, in this technology, each of the multiple foils 25 is arranged to align with the direction of emission of radiation R. As a result, radiation R is less likely to be reflected by the foils 25, making it possible to extract radiation R more efficiently.

[0092] Furthermore, in this technology, the foil 25 and other components are configured such that the length L (m) of the foil 25 in the direction of the ejection axis EA, the moving speed V (m / s) of the rotating body 20 at the irradiation position I, and the characteristic length I (m) satisfy L ≥ 70I / V. This makes it possible to reliably cause the debris to collide with the foil 25.

[0093] Furthermore, in this technology, the housing 24 of the debris reduction member 22 has a frustoconical shape. As a result, the internal space S of the housing 24 is shaped to align with the optical path of the radiation R, making it possible to extract the radiation R more efficiently.

[0094] <Other Embodiments> This technology is not limited to the embodiments described above, and various other embodiments can be realized. [Combination of Multiple Thin Plate Structures] Figure 9 is a schematic diagram showing a divided foil 28. Foil 28 is a foil positioned in the center in the C direction and corresponds to foil 25d in Figure 3, etc. Figure 9 shows the foil 28 as viewed from the direction of arrow A in Figure 2, with the irradiation position I on the left side. Note that the rotating body 20 is not shown. In this embodiment, the foil 28 has a shape in which a single, undivided surface shape is divided by a plane perpendicular to the radiation emission axis EA of the radiation R.

[0095] The "single, unseparated surface shape" corresponds to the trapezoidal planar shape of foil 25d. The "plane perpendicular to the radiation emission axis EA" corresponds to the BC plane (XZ plane). Foil 28 consists of foils 28a to 28c, which are obtained by dividing the trapezoidal planar shape into three parts by the BC plane. Each of foils 28a to 28c also has a trapezoidal planar shape.

[0096] It can be said that foils 28a to 28c are arranged in a substantially continuous manner. That is, if we ignore the divided parts, foils 28a to 28c are continuous. For example, the positions of the right end of foil 28a and the left end of foil 28b in the C direction are not significantly different.

[0097] When the lateral length L of foil 25d is large, it may be difficult to form foil 25d as a single piece. In such cases, the method of using divided foil 28 as in this example is effective. In this case, the conditional formula is applied with L being the combined length of the three foils 28a to 28c, and I being the representative length at the rightmost end of the rightmost foil 28c.

[0098] The foils 25 positioned other than the center may be similarly divided. Furthermore, the foils 25 with shapes other than trapezoidal planar shapes may also be similarly divided. In addition, within the scope of what is feasible for this technology, division may be performed using planes other than those perpendicular to the radiation emission axis EA, and the specific number of divisions is not limited.

[0099] In contrast to this example, the foil 25 in Figure 3, etc., has a single, undivided surface shape. That is, the foil 25 is integrally constructed from a single member. Furthermore, this single surface shape acts as a partition, separating the internal space S into multiple distinct spaces. By using such a configuration, it becomes possible to more reliably cause debris to collide with the foil 25.

[0100] Furthermore, even if the foil 25 has small holes, for example, it is still considered to have a single, undivided surface shape. In such cases, a gas introduction section, described later, may be configured, and holes may be provided in the foil 25 to allow gas to pass through.

[0101] [Addition of thin sheets of different lengths] Figure 10 is a schematic diagram showing an example of the configuration of an additional foil 31. In this example, the additional foil 31 is inserted between foils 25d and 25e. Foils 25d and 25e have the same length L (m) in the Y direction. On the other hand, the additional foil 31 has a length shorter than L (m) in the Y direction. The positions of the right ends of foils 25d, 25e, and 31 in the figure are approximately the same. Foil 25 corresponds to one embodiment of the first foil according to this technology. Additional foil 31 corresponds to one embodiment of the second foil according to this technology.

[0102] The foils 25 and 31 are arranged alternately in the direction of movement of the rotating body 20. That is, in direction C, they are arranged in the order of foil 25d, 31, and 25e, with the 31 being sandwiched between the foils 25.

[0103] The arrangement is not limited to this configuration; multiple additional foils 31 may be placed between the two foils 25. Furthermore, smaller additional foils 31 may be placed between the two additional foils 31. The specific configuration of the additional foils 31, including their length, number, and arrangement, is not limited.

[0104] When a large number of foils 25 are arranged, the foils 25 may become densely packed near the left end, obstructing the propagation of radiation R. In such cases, by adopting a configuration in which additional foils 31 are arranged from the middle, as in this example, it becomes possible to arrange the foils 25 without difficulty. In this case, the characteristic length at the right end of the foils 25 and additional foils 31 is denoted as I, and the conditional formula is applied.

[0105] [Gas Inlet] A gas inlet may be provided, and gas may be introduced at a position closer to the irradiation position I than to the foil 25. For example, as a gas inlet, a gas inlet hole is provided in the inner wall of the housing 24, near the opening 26. When gas flows in from this gas inlet hole, the space T (shown in Figures 3 and 4) near the irradiation position I outside the debris reduction member 22 and the internal space S of the housing 24 become filled with gas. This gas filling causes the debris to lose speed and become slow debris. As a result, more debris is removed by the foil 25, making it possible to improve the debris reduction effect.

[0106] Alternatively, the gas nozzle may be positioned so that its tip faces into space T. The gas supply source for the gas inlet section may be the same for the gas injection passages 116a and 116b. The specific configuration of the gas inlet section is not limited to these other aspects.

[0107] Furthermore, buffer gases such as argon or hydrogen gas can be used as the gas. Any other type of gas may also be used.

[0108] [Shape of the foil] For example, a nest-type foil may be used as foil 25. Each nest-type foil has a frustoconical shape with a different radius, and these are arranged in a nested manner. The cross-section of multiple nest-type foils by the BC plane will have a shape of concentric circles, like the cross-section of an onion.

[0109] Since each nested foil is arranged so that at least one part intersects with the direction of movement of the rotating body 20, it can be said that they are arranged to intersect with the direction of movement. Furthermore, the difference in the radii of the concentric circles at the end furthest from the irradiation position I is the characteristic length.

[0110] Alternatively, honeycomb-shaped foil may be used. Honeycomb-shaped foil has a hexagonal structure in cross-section, similar to a beehive, and extends in one direction while expanding or contracting this cross-section.

[0111] Even if two sides of the hexagon of the honeycomb foil are parallel to the direction of movement, the remaining four sides will intersect with the direction of movement. Therefore, it can be said that the foil is arranged to intersect with the direction of movement. In addition, any shape of foil 25, such as a combination of polygonal pyramids, may be used within the scope of what is feasible for this technology.

[0112] [Number of foils, etc.] As an example, the characteristic length can be a value such as I = 5.3 (mm) or less. Also as an example, if the intake angle (the inclination of both sides of the housing 24 with respect to the output axis EA) is 20°, the length of the foil 25 in the Y direction is L = 100 (mm), and the distance between the irradiation position I and the end of the foil 25 on the irradiation position I side is 10 (mm), then 14 foils 25 are used.

[0113] [Types of Plasma Materials] The specific type of plasma material 101 is not limited. For example, not only completely liquid plasma material 101, but also plasma material 101 in which solid material in the process of melting is mixed in with the liquid may be used.

[0114] [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.

[0115] 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.

[0116] EA... Exit axis EB... Energy beam I... Irradiation position R, R'... Radiation S... Internal space 20... Rotating body 22... Debris reduction member 23... Main surface 24... Housing 25, 28... Foil 31... Additional foil 100... Light source device 101... Plasma raw material 103... Vacuum chamber 106... Plasma generation mechanism 108... Beam source

Claims

1. A light source device for generating radiation by plasmaizing a raw material by injecting energy, comprising: a chamber; a rotating body housed in the chamber and rotatable about a predetermined axis of rotation, having a region to which the raw material is attached; an energy source for injecting the energy into the region and generating the plasma at the energy injection position; and a plurality of foils having a planar shape, wherein each of the plurality of foils is positioned such that the end closest to the injection position faces the injection position and intersects with the direction of movement of the rotating body at the injection position.

2. A light source device according to claim 1, wherein each of the plurality of foils is arranged such that the ends furthest from the injection position are aligned at the same distance in the direction of movement.

3. A light source device according to claim 1, wherein each of the plurality of foils is arranged along the direction of emission of the radiation.

4. A light source device according to claim 1 or 2, further comprising a housing having an internal space through which the radiation passes and through which the plurality of foils are arranged, wherein each of the plurality of foils has a single, unseparated surface shape, and the internal space is separated by the single surface shape.

5. A light source device according to claim 1 or 2, wherein each of the plurality of foils has a shape obtained by dividing a single, unseparated surface shape with a plane perpendicular to the radiation emission axis.

6. A light source device according to claim 1 or 2, wherein each of the plurality of foils has the same length L (m) in the direction of the radiation emission axis, and L ≥ 70I / V, where V (m / s) is the moving speed of the rotating body at the injection position and I (m) is the spacing between them.

7. A light source device according to claim 1 or 2, wherein the distance between the ends of each of the plurality of foils furthest from the injection position in the direction of movement is 5.3 mm or less.

8. A light source device according to claim 1 or 2, wherein each of the plurality of foils comprises a plurality of first foils having the same length in the direction of the radiation emission axis, and a plurality of second foils having a length in the direction of the emission axis that is shorter than the length of the first foils, and the first foils and the second foils are arranged alternately in the direction of movement.

9. A light source device according to claim 1 or 2, further comprising a gas introduction unit for introducing gas at a position closer to the injection position than the plurality of foils.

10. A light source device according to claim 1 or 2, wherein each of the plurality of foils has a planar shape.

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