Light source device and radiation extraction method

Abstract

To provide a light source device and a radiation extraction method that enable the efficient removal of debris. [Solution] The raw material supply unit supplies raw materials to the energy irradiation position. The energy source injects energy into the energy irradiation position to generate plasma. The port has a conduit and is arranged so that radiation or energy passes through its internal space, with the area of ​​the downstream opening being larger than the area of ​​the emission-side opening. The gas introduction unit is located closer to the energy irradiation position than the downstream opening. The minimum value S(mm) of the cross-sectional area of ​​the conduit and internal space by a plane perpendicular to the optical axis of the radiation or the optical axis of the energy 2 The aperture angle θ of port 23 is determined by the distance X (mm) between the energy irradiation position and the cross section with the minimum cross-sectional area, and the distance d (mm) between the energy irradiation position and the light-emitting aperture is determined based on the aperture angle θ.

Description

[Technical Field]

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

[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 inspected using a method called actinic inspection, which uses radiation at a wavelength that matches the working wavelength 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 (Discharge Pressure) light source device utilizes extreme ultraviolet light emitted from a gaseous plasma material (discharge gas) containing EUV emitting species by applying a high voltage between electrodes to which a gaseous plasma material (discharge gas) is supplied, thereby generating a high-density, high-temperature plasma through discharge.

[0006] An LDP light source device is an improved version of a DPP light source device. For example, it supplies liquid high-temperature plasma raw materials 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 raw materials with a laser beam to vaporize them, and then generates high-temperature plasma by discharge.

[0007] LPP (Low-Pressure Pulsed Light) light sources generate high-temperature plasma by exciting EUV-emitting 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 rays 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 (Low-Power Plasma) method, but it uses the centrifugal force of a rotating body to supply liquid plasma material to the energy beam irradiation area, 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. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2014-216286 [Overview of the project] [Problems that the invention aims to solve]

[0011] In light source devices such as those described in Patent Document 1, there is a need for technology that can efficiently remove 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 and a radiation extraction method that enable the efficient removal of debris. [Means for solving the problem]

[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 through energy injection, and comprises a chamber, a raw material supply unit, an energy source, a radiation extraction unit, and a gas introduction unit. The raw material supply unit is housed in the chamber and supplies the raw material to the energy irradiation position. The energy source injects the energy at the energy irradiation position to generate plasma. The port has a conduit, and is arranged such that the radiation or energy passes through the internal space surrounded by the conduit, and in the arrangement, when the opening closer to the energy irradiation position is designated as the light-emitting side opening and the opening further away is designated as the downstream side opening, the area of ​​the downstream side opening is larger than the area of ​​the light-emitting side opening. The gas introduction section is configured to be closer to the energy irradiation position than the downstream opening. The minimum cross-sectional area of ​​the conduit and the internal space, measured by a plane perpendicular to the optical axis of the radiation or the optical axis of the energy, is S(mm²). 2 Let X (mm) be the distance between the energy irradiation position and the cross-section with the minimum cross-sectional area.

number

number

[0014] In this light source device, a radiation extraction part having an area of a downstream-side opening larger than that of a light-emitting-side opening is arranged, and a gas introduction part is configured at a position closer to the energy irradiation position than the downstream-side opening. Further, the minimum value of the cross-sectional area of the radiation extraction part, the distance between the energy irradiation position and the cross-section where the cross-sectional area is minimum, and the distance between the energy irradiation position and the light-emitting-side opening satisfy a predetermined relational expression. Thereby, it becomes possible to efficiently remove debris.

[0015] The port may be arranged such that the internal space surrounded by the conduit allows the radiation to pass through. In this case, the S (mm 2 ) may be the minimum value of the cross-sectional area of the conduit and the internal space by a plane perpendicular to the optical axis of the radiation.

[0016] The port may be arranged such that the internal space surrounded by the conduit allows the energy to pass through. In this case, the S (mm 2 ) may be the minimum value of the cross-sectional area of the conduit and the internal space by a plane perpendicular to the optical axis of the energy.

[0017] The light source device may further include a debris reduction device that captures debris generated at the energy irradiation position.

[0018] In the light source device, 5° ≤ θ ≤ 20° may be satisfied.

[0019] The conduit may have a frustum of a cone shape.

[0020] The conduit may have two opposing substantially fan-shaped surfaces and two opposing rectangular surfaces.

[0021] The gas introduction part may be an opening formed in the conduit. [[ID=3,7]]

[0022] The gas introduction part may be configured in a space between the energy irradiation position and the light-emitting-side opening.

[0023] The raw material supply unit may have a housing that surrounds the energy irradiation position and forms a plasma generation space.

[0024] The port may be fixed to the housing.

[0025] The light source device may further include a focusing mirror positioned on the optical axis at a location further from the energy irradiation position than the port. In this case, the chamber may have a partition separating the port and the focusing mirror. The port may also be fixed to the partition.

[0026] The minimum cross-sectional area of ​​the internal space only, as defined by the aforementioned plane, is S(mm) 2 Even in the case of ), the condition 5°≦θ≦20° may still hold.

[0027] The port may have an adjustment mechanism for adjusting the position of the conduit.

[0028] The light source device may further include a measuring unit for measuring the amount of gas introduced by the gas introduction unit.

[0029] A radiation extraction method according to one form of this technology is a light source device that generates radiation by turning a raw material into plasma through energy injection, Chamber and, A raw material supply unit housed in the chamber and supplying the raw material to the energy irradiation position, An energy source that injects the energy at the energy irradiation position to generate plasma, A port having a conduit, arranged such that the radiation or energy passes through the internal space surrounded by the conduit, wherein in the arrangement, the opening closer to the energy irradiation position is designated as the light-emitting side opening, and the opening further away is designated as the downstream side opening, and the area of ​​the downstream side opening is larger than the area of ​​the light-emitting side opening, A gas introduction section is configured at a position closer to the energy irradiation position than the downstream opening. In a light source device comprising, The minimum cross-sectional area of ​​the conduit and the internal space, measured by a plane perpendicular to the optical axis of the radiation or the optical axis of the energy, is S(mm²). 2 )year, Let X (mm) be the distance between the energy irradiation position and the cross-section with the minimum cross-sectional area.

number

number

[0030] According to the present invention, it is possible to efficiently remove debris. However, the effects described herein are not necessarily limited, and any of the effects described herein may be present. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram showing an example configuration of the light source device according to this embodiment. [Figure 2] This is a schematic diagram showing an example of a port configuration. [Figure 3] This is a diagram illustrating the overview of the simulation model. [Figure 4] This graph shows the relationship between conductance and the P×D value. [Figure 5] This diagram shows the shape and arrangement of the ports. [Figure 6] This graph shows the relationship between d, L, and θ. [Figure 7] This is a graph showing the relationship between d and θ. [Figure 8] This is a schematic diagram showing an example of a distorted port configuration. [Figure 9A] This is a schematic diagram showing how to fix a port. [Figure 9B] This is a schematic diagram showing how to fix a port. [Figure 10] This is a schematic diagram showing examples of variations in port shape. [Figure 11] This is a schematic diagram showing an example of the configuration of an injection unit. [Modes for carrying out the invention]

[0032] [Basic configuration of a light source device] Figure 1 is a schematic diagram showing an example configuration of the light source device 100 according to this embodiment. The light source device 100 is an LPP (Low-Power Plasma) type light source device. That is, the light source device 100 is a device that generates plasma P by irradiating the plasma material 101 with an energy beam EB, 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. Energy beam EB represents one embodiment of energy.

[0033] The plasma raw material 101 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. Plasma raw material 101 corresponds to one embodiment of the raw material.

[0034] 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 diagram 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.

[0035] 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.

[0036] 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.

[0037] 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 housing 102 along the incident axis IA. An electron beam or laser light can be used as the energy beam EB. The beam source corresponds to one embodiment of the energy source.

[0038] The light source device 100 is provided with a chamber section C that includes multiple 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.

[0039] 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 located inside the exit chamber 105. A plasma generation mechanism 106 for generating plasma P is located inside the vacuum chamber 103.

[0040] 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 (e.g., an inert gas) from a gas injection passage as needed, and exhausted by an exhaust means not shown. A filter membrane 111 or an opening is provided between the application chamber 110 and the ejection chamber 105 to physically separate the region where plasma P is generated from the application chamber 110.

[0041] The chamber body 109 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 chamber body 109.

[0042] 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.

[0043] 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. The plasma generation mechanism 106 includes a rotating body 20 as shown in Figure 1.

[0044] 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 incident axis IA and the exit axis EA.

[0045] The plasma generation mechanism 106 corresponds to one embodiment of the raw material supply unit. Irradiation position I corresponds to one embodiment of the energy irradiation position.

[0046] 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 chamber body 109 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.

[0047] 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 chamber body 109. This ensures smooth rotation while maintaining the airtightness of the vacuum chamber 103.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Furthermore, as shown in Figure 1, in this embodiment, a radiation diagnostic unit 119 is connected to the chamber body 109. The radiation diagnostic unit 119 is positioned where radiation R is incident, radiated in a direction different from the radiation R emission axis EA, and measures the state of radiation R emitted from the plasma P.

[0052] Furthermore, in this embodiment, a light extraction unit 22 is positioned between the irradiation position I and the emission chamber 105. In Figure 1, the position where the light extraction unit 22 is positioned is schematically shown by a shaded rectangle.

[0053] [Port configuration example] Figure 2 is a schematic diagram showing an example configuration of port 23. Figure 2 schematically illustrates the entire light extraction unit 22. The light extraction unit 22 has a port 23, a focusing mirror 24, and a flow meter 28. Note that the angle of the rotating body 20 and the irradiation position I on the rotating body 20 are different in Figures 1 and 2, but the arrangement of the rotating body 20 and the specific irradiation position I may be arbitrary.

[0054] Port 23 is a mechanism for extracting radiation R and has a conduit 25. In this embodiment, the conduit 25 has a frustoconical shape and has a smaller diameter opening 26a and a larger diameter opening 26b. That is, the area of ​​opening 26b is larger than the area of ​​opening 26a. The shape of the internal space T surrounded by the conduit 25 is also a frustoconical shape, and port 23 is positioned so that radiation R passes through this internal space T.

[0055] In this embodiment, the port 23 is positioned such that the central axis of the frustum of the conduit 25 coincides with the emission axis EA of the radiation R. That is, the conduit 25 faces the irradiation position I, and its central axis is parallel to the Y-axis. In Figure 2, the emission axis EA (which is also the central axis of the conduit 25) is shown as a dashed line. Furthermore, the port 23 is positioned such that the opening 26a is closer to the irradiation position I, and the opening 26b is further away from the irradiation position I. The opening 26a corresponds to one embodiment of the light-emitting side opening according to this technology. The opening 26b corresponds to one embodiment of the downstream opening according to this technology.

[0056] The radiation R is emitted from the irradiation position I in all directions within the hemisphere, but due to the arrangement of the ports 23, some of the radiation R passes through the entire internal space T. In Figure 2, the radiation R passing through the internal space T is illustrated with a shaded area.

[0057] In addition, any other arrangement is possible in which the radiation R passes through the internal space T. For example, the central axis of the conduit 25 may be slightly inclined with respect to the emission axis EA. Furthermore, the conduit 25 may have any cylindrical shape such that the area of ​​the downstream opening is larger than the area of ​​the emission-side opening.

[0058] Furthermore, in this technology, the gas introduction section is configured closer to the irradiation position I than to the opening 26b. In particular, in this embodiment, the gas inlet 27 is configured in the conduit 25 as the gas introduction section. Specifically, the gas inlet 27 is configured on the cylindrical side surface of the conduit 25, at a position close to the opening 26a.

[0059] The gas inlet 27 communicates with the internal space T and a gas supply source (not shown). This gas supply source may be the same as the gas supply source for the gas injection passage 116a or 116b in Figure 1. When the gas supply source is driven, gas is introduced into the internal space T through the gas inlet 27. As the gas, for example, argon or other inert gases can be used. Note that multiple gas inlets may be configured.

[0060] The focusing mirror 24 is positioned downstream of the port 23 (on the right side in Figure 2). In Figure 2, the focusing mirror 24 is schematically shown as a rectangular block, but any shape of focusing mirror 24 that can focus the radiation R, such as a convex lens or a nested mirror, may be used. The radiation R refracted by the focusing mirror 24 converges to a point downstream of the focusing mirror 24, as shown in Figure 2, and then diffuses again before entering the exit chamber 105 in Figure 1.

[0061] The flow meter 28 is a mechanism for measuring the flow rate of gas introduced into the internal space T through the gas inlet 27. The flow meter 28 outputs the gas flow rate in units such as sccm (Standard Cubic Centimeter per Minute). Figure 2 schematically shows the flow meter 28 as a block, but the specific type and arrangement of the flow meter 28 are not limited. The flow meter 28 corresponds to one embodiment of the meter side part according to this technology.

[0062] [Debris removal] At irradiation position I, debris is generated simultaneously with the generation of plasma P. Like radiation R, the debris is emitted in all directions within the hemisphere. Of this debris, the debris emitted in the direction of the focusing mirror 24 adversely affects the focusing mirror 24 and other optical components. For example, sputtering (where the reflective surface is abraded by the debris), deposition (where the debris accumulates on the reflective surface), or implantation (where the debris is driven deep into the reflective surface) can occur. These impair the function of the optical components and reduce the overall performance of the light source device 100. Therefore, some measure is needed to protect the optical components from the debris.

[0063] In this embodiment, a port 23 is provided to capture the debris, and gas is introduced into the internal space T. As a result, the internal space T and the space between the irradiation position I and the aperture 26a are filled with gas. When the debris passes through the internal space T, etc., it collides with the gas particles filling the internal space T, etc., and the debris, having lost kinetic energy due to the collision, is removed from the optical path along the gas flow.

[0064] Since debris loses kinetic energy upon collision, the ability to remove debris depends on the length of the space where the gas is introduced in the direction of the exit axis EA, and the density of the gas particles. Here, the density of the gas particles can be considered as the gas pressure. In other words, the larger the P × D value, which is the product of the average value P of the gas pressure along the optical path and the length D of the high-pressure space in the direction of the exit axis EA, the greater the debris removal ability.

[0065] The range of the region where the pressure is locally increased varies depending on the light source's emission method. However, in a plasma generation light source like this one, which forms a layer of molten metal fuel on a rotating disk or drum and irradiates that metal layer with an energy beam EB, it is possible to raise the gas pressure around the light-emitting part (irradiation position I) to a relatively high level. This is because this method is less affected by the increase in pressure around the light-emitting part compared to plasma generation using, for example, electrical discharge.

[0066] Therefore, this method makes it possible to configure a system that forms a high-pressure region around the light-emitting part. The formation of such a localized high-pressure region can be achieved by devising the shape and arrangement of the port 23.

[0067] Here, one might consider increasing the gas introduction rate to raise the average gas pressure P. However, increasing the gas flow rate would necessitate a larger exhaust system. Therefore, there is a limit to the gas flow rate, and it is preferable to keep it below 3000 sccm, which can be easily handled by a combination of commercially available large turbomolecular pumps, etc. That is, if the gas flow rates introduced from multiple gas inlets are Q1, Q2, Q3, ..., then the sum of their flow rates is ΣQ. i , ΣQ i The value should be ≤ 3000 sccm.

[0068] [simulation] Figure 3 shows a schematic diagram of the simulation model. The inventor conducted a simulation to obtain a conductance C such that sufficient debris removal performance is achieved. Conductance is a value representing the ease of gas flow. The larger the C, the easier the gas flows, and the smaller the C, the more difficult the gas flows.

[0069] In FIG. 3, the experimental port 31 used in the simulation is shown. The port 31 has a cylindrical shape, and gas was introduced (dashed arrow) from a position on its side surface close to the bottom surface on the light-emitting point side.

[0070] Here, the conductance from the gas introduction position to the outlet (right end) of the port 31 is designated as C (solid arrow). Also, the outflow direction of the gas is assumed to be the outlet side of the port 31. Note that although the purpose of this simulation is to obtain the conditions of the conductance C, in the actual light source device 100, the introduced gas particles may go toward both the light-emitting point side and the outlet side, and may also be adsorbed on the inner wall of the port 23 or the like.

[0071] The flow rate of the gas to be introduced satisfies the above conditions (ΣQ i ≦3000 sccm), and as a value that can actually be adopted, it was set to 1200 sccm. Also, the exhaust speed was appropriately set so that the space outside the outlet side of the port 31 becomes 2 Pa.

[0072] FIG. 4 is a graph showing the relationship between the conductance and the P×D value. Under the above conditions, the inventor measured the relationship between the conductance C and the P×D value. The conductance C is taken on the horizontal axis of the graph, and here its unit is m 3 / sec. The P×D value (Pa·cm) is taken on the vertical axis. Here, the P×D value is the value at a position that is 10 cm away from the light-emitting point toward the port 31 side.

[0073] As shown in Figure 4, a straight line showing the relationship between C and the P×D value was obtained by linearly approximating the three points obtained from the simulation results. Here, paragraph

[0079] of Japanese Patent Application Publication No. 2007-298980 states that a P×D product of 500 mT·cm is a preferred value for reducing debris. Converting this value to the numerical value on the vertical axis of Figure 4, it is 66.7 Pa·cm. Therefore, reading from the graph, the conductance C is 0.07 m 3 The result indicated that it needs to be less than or equal to / sec.

[0074] Figure 5 shows the shape and arrangement of port 23. The inventor further stated that for a port 23 having the shape of a frustocone, the conductance C is 0.07 m 3 We considered what shape and arrangement of port 23 is necessary to achieve a value of less than / sec. In particular, we examined the conditions that must be satisfied for the distance d (mm) between the irradiation position I and aperture 26a shown in Figure 2, and for the aperture angle θ of port 23 (the inclination of the side relative to the emission axis EA).

[0075] As shown in Figure 5, let L (mm) be the length of port 23 in the direction of the discharge axis EA. Also, let a (mm) be the characteristic length obtained by adding the thickness (margin) of the conduit 25 to the radius of opening 26b. Similarly, let b (mm) be the value obtained by adding the thickness of the conduit 25 to the radius of opening 26a.

[0076] Then,

number

number

[0077] Furthermore, the conductance C is approximately

number

[0078] Substituting equations (3) and (4) into equation (5) yields the relationship between C, d, L, and θ. Furthermore, the above C ≤ 0.07(m 3 Using the condition ( / sec), a conditional equation that d, L, and θ must satisfy can be obtained. The inventor further substituted several predetermined values ​​for L and calculated what the conditional equation that d and θ must satisfy would look like.

[0079] Figure 6 is a graph showing the relationship between d, L, and θ. The inventor substituted five different values ​​for L—5mm, 25mm, 50mm, 75mm, and 100mm—and investigated the relationship between d and θ for each value. The vertical axis of the graph represents d (mm), and the horizontal axis represents θ (°). Furthermore, the graph is illustrated with different line and point types for each value of L.

[0080] For each value of L, the region where d and θ satisfy the condition corresponds to the region to the lower left of the graph. For example, in the case of L=5mm, d=50mm, and θ=10°, the point where d=50mm and θ=10° is to the lower left of the graph for L=5mm, so the condition is satisfied. That is, C≦0.07(m 3 This results in a state where the P×D value is 66.7 Pa·cm or higher ( / sec).

[0081] As shown in the graph, it was found that the relationship between d and θ does not change much with the value of L. Therefore, the inventor approximated these multiple graphs and obtained a conditional equation that includes only d and θ.

[0082] Figure 7 is a graph showing the relationship between d and θ. Approximating each of the graphs in Figure 6 yielded the relationship shown in the graph in Figure 7. The equation for the region to the lower left of this graph is:

number

[0083] Furthermore, the experiment yielded the following results. (1) In general, in order to obtain sufficient radiation R output, it is desirable that the aperture angle be θ≧5°. (2) Since the debris removal performance strongly depends on the minimum area of ​​the opening, higher debris removal performance can be achieved if θ ≤ 20°. (3) Regarding d under the condition θ≦10°, since the amount of radiation R taken up increases as you get closer to the plasma P, d≦100(cm) is preferable.

[0084] Figure 8 is a schematic diagram showing an example of the configuration of a distorted port 34. The shape of a port can vary depending on its intended use and any additional mechanisms added. Through repeated experiments, the inventor discovered that even a typical port 34 (not limited to a truncated cone shape) as shown in Figure 8 can achieve debris removal performance if the following conditions are met.

[0085] (conditions) S(mm) is the minimum value of the cross-sectional area of ​​the conduit 35 and the internal space T, defined by a plane perpendicular to the ejection axis EA. 2 Let X (mm) be the distance between the irradiation position I and the cross-section with the minimum cross-sectional area.

number

number

[0086] The cross-section that minimizes the cross-sectional area S can take on any shape, but it could be a polygon such as a triangle or rectangle, a perfect circle, or an ellipse. In particular, in the case of port 23 which has the shape of a frustocone as shown in Figure 5, the cross-section is a perfect circle.

[0087] In Figure 8, the "plane perpendicular to the exit axis EA" is the XZ plane. Furthermore, the position where the cross-sectional area of ​​the conduit 25 and the internal space T is minimized by the XZ plane is the constriction position 37 of the port 34. In this example, the constriction position 37 can also be said to be the part that most restricts the shape of the radiation R. Moreover, the constriction position 37 can be said to be the part that defines the shape of the projection of radiation R at the downstream opening 36b.

[0088] Therefore, in this example, the cross-sectional area at the constriction is S, and the distance between this cross-section and the irradiation position I is X. Substituting these values ​​of S and X into equation (1) gives θ, which must satisfy equation (2).

[0089] Furthermore, it has been found that even for such a general port 34, higher debris removal performance can be achieved if the angle is 5°≦θ≦20°, similar to (1) and (2) above.

[0090] Furthermore, for port 23, which has a frustoconical shape, the θ obtained by equation (Equation 1) coincides with the true θ shown in Figure 5. This will be explained. First, in Figure 5, the "plane perpendicular to the exit axis EA" is the XZ plane. The position where the cross-sectional area of ​​the conduit 25 and the internal space T is minimized by the XZ plane is the position of the opening 26a. Therefore, S is the sum of the cross-sectional area of ​​the conduit 25 and the cross-sectional area of ​​the internal space T at the position of the opening 26a. Thus, S = πb 2 This is the result.

[0091] Furthermore, since X is the distance between the irradiation position I and the aperture 26a, X = d. Therefore, substituting these values ​​of S and X into the right-hand side of equation (Equation 1), we get θ = tan -1 We obtain (b / d). This value of θ is equal to the true value of θ.

[0092] In the light source device 100 according to this embodiment, a port 23 is provided in which the area of ​​the opening 26b is larger than the area of ​​the opening 26a, and a gas inlet 27 is configured closer to the irradiation position I than to the opening 26b. Furthermore, the minimum value S of the cross-sectional area of ​​the port 23, the distance X between the irradiation position I and the cross-section with the minimum cross-sectional area, and the distance d between the irradiation position I and the opening 26a satisfy a predetermined relational expression. This makes it possible to efficiently remove debris.

[0093] Debris is generated from the plasma P in various forms, such as droplets, clusters, neutral particles, and ions. The generated debris causes damage events such as deposition, sputtering, and implantation to optical components such as the focusing mirror 24 and structures within the vacuum chamber 103. In this embodiment, gas is introduced into the internal space T of the port 23 to remove the debris, creating a localized high-pressure space.

[0094] In this case, the light source device 100 is required to always increase the output of radiation R. One way to do this is to increase the intensity of the input energy beam EB, but there is a limit to that intensity. Therefore, it is necessary to make the aperture angle of the port 23 from which radiation R is extracted as large as possible.

[0095] However, increasing the opening angle increases the amount of debris that enters port 23. Furthermore, the gas conductance increases, reducing the debris removal efficiency. Therefore, it was necessary to appropriately configure the shape and arrangement of port 23 to ensure sufficient debris removal while maximizing the radiation output R.

[0096] In this technology, the shape and arrangement of the port 23 are defined to satisfy predetermined conditions, making it possible to ensure sufficient debris removal performance and radiation output R. In other words, it becomes possible to remove debris efficiently.

[0097] Furthermore, in this technology, the conduit 25 has a frustoconical shape. As a result, the shape of the internal space T is aligned with the radiation R, making it possible to further increase the output of the radiation R.

[0098] Furthermore, in this technology, a gas inlet 27 is configured in the conduit 25 as the gas introduction section. This makes it possible to introduce gas more efficiently into the internal space T and the space between the irradiation position I and the opening 26a.

[0099] Furthermore, in this technology, the gas flow rate is measured by a flow meter 28. This makes it possible to introduce the appropriate amount of gas.

[0100] <Other Embodiments> This technology is not limited to the embodiments described above, and various other embodiments can be realized. In the following description, parts that are similar to the configuration and operation of the light source device 100 described in the above embodiments will be omitted or simplified.

[0101] [Placement on the incident side] An injection unit 50, having a configuration substantially identical to that of the light extraction unit 22, may be placed on the injection side of the energy beam EB. In Figure 1, the position where the injection unit 50 is placed is indicated by a shaded rectangle. When the injection unit 50 is installed, it is possible to use the injection chamber 104 in combination as shown in Figure 1, but it is also possible to install only the injection unit 50 without providing a special compartment such as the injection chamber 104.

[0102] Figure 11 is a schematic diagram showing an example configuration of the injection unit 50. The injection unit 50 includes a port 51 and a flow meter 52, which have the same configuration as those in the light extraction unit 22. A focusing mirror is not included. Figure 11, like Figure 1, shows each mechanism viewed from the positive side in the Z direction, which is a different viewing orientation from Figure 2.

[0103] The internal space T' of the conduit 53 is the space through which the energy beam EB passes. This figure only shows the incident axis IA of the energy beam EB. Also, similar to the light extraction unit 22, the minimum value of the cross-sectional area of ​​the conduit 53 and the internal space T' by a plane perpendicular to the incident axis IA of the energy beam EB is S(mm²). 2 When this is the case, the conditions of equation (2) and 5°≦θ≦20° are satisfied. This makes it possible to suppress the amount of debris flying towards the incident side, and a further debris reduction effect is achieved.

[0104] Furthermore, as in this example, by installing a Debris Mitigation Tool (DMT) between the focusing mirror 24 and the plasma P generated by the energy beam EB on the radiation R emission side, it is also possible to guide the radiation R to the focusing mirror 24 while reducing debris. The debris mitigation tool 54 may be any mechanism capable of capturing debris, such as a foil trap. The debris reduction tool 54 corresponds to one embodiment of the debris reduction device according to this technology.

[0105] In this configuration, it is also possible to install a port 23 instead of the debris reduction tool 54 and configure a light extraction unit 22 similar to that in Figure 2. That is, ports 53 and 23 may be installed on both the input and output sides. If there are no space limitations from the plasma P to the focusing mirror 24, it is also possible to use the debris reduction tool 54 and port 23 together. In this case, it is preferable to use them together because it is expected that debris can be reduced significantly.

[0106] [Device configuration, etc.] The light extraction unit 22 may be positioned to communicate with multiple connected chambers. For example, the first to third chambers may be connected by a partition wall, with an opening provided in each partition wall for the passage of radiation R. The rotating body 20 and port 23 may be positioned in the first chamber, the focusing mirror 24 in the second chamber, and the radiation R may be focused to a single point in the third chamber.

[0107] If the aperture angle of port 23 is increased, or if port 23 is brought closer to the irradiation position I, a portion of port 23 may overlap with the path of the energy beam EB, obstructing the propagation of the energy beam EB. In such cases, an aperture may be provided in port 23 to allow the energy beam EB to pass through.

[0108] Even if the shape of the internal space T differs slightly from a precise frustocone due to a protrusion on part of the inside of port 23, the conditional equation can be applied under a shape that ignores the differing part. In other words, in practice, the most important elements of the shape of port 23 are the opening angle θ and the distance d, and the internal structure and fine details of port 23 are relatively insensitive.

[0109] In the example shown in Figure 1, the light extraction unit 22 is positioned on the path of radiation R toward the utilization device, but the light extraction unit 22 may also be positioned on the path toward the radiation diagnostic unit 119, etc. Furthermore, the specific location where the light extraction unit 22 is positioned is not limited.

[0110] A debris removal mechanism may be provided downstream of port 23 (near the opening 26b). Possible debris removal mechanisms include, for example, installing multiple thin plates or a thin film that allows a portion of the radiation R to pass through. In this case, it can be said that the debris removal mechanism separates port 23 and a portion of the internal space T, but these can still be considered as a single port 23 when applying the conditions of this technology.

[0111] The focusing mirror 24 may be placed inside the port 23. In this case, only the portion of the port 23 closer to the irradiation position I than the focusing mirror 24 may be considered, and the conditional expression may be applied to that portion.

[0112] [Gas inlet] The gas introduction section may be configured at any position closer to the irradiation position I than the opening 26b. However, it is preferable that the gas pressure distribution be relatively high between the irradiation position I and the port 23 or focusing mirror 24, and low downstream. This is because the larger the high-pressure region, the more radiation R is absorbed by the gas. Therefore, it is preferable that C1 ≥ C2 when the conductance from the gas introduction section to the irradiation position I is C1 and the conductance from the gas introduction section to the focusing mirror 24 is C2.

[0113] A configuration may be adopted in which the tip of the gas nozzle is positioned in the space between the irradiation position I and the opening 26a. In this case, a gas supply source is connected to the other end of the gas nozzle. This makes it possible to further efficiently increase the gas pressure around the irradiation position I. The gas nozzle corresponds to one embodiment of the gas introduction section according to this technology.

[0114] The specific type of gas introduced through the gas inlet is not limited, and any type of gas can be used as long as it is feasible for this technology. For example, using argon makes it possible to obtain high debris removal performance at a low cost. Hydrogen gas may also be used. In this case, hydrogen combines with tin, which is debris, to produce stannane, and the debris is removed when the stannane vaporizes.

[0115] [How to fix a port] Figures 9A and 9B are schematic diagrams showing how port 23 is fixed. In the example shown in Figure 9A, the plasma generation mechanism 106 includes a housing 19, and the rotating body 20 is positioned inside the housing 19. The housing 19 typically serves as a cover member that covers the rotating body 20 and the like. Although not shown in the figure, the housing 19 is provided with an opening for the energy beam EB to enter and an opening for the radiation R to exit.

[0116] The housing 19 is provided to prevent droplets of the plasma raw material 101 from scattering to the outside due to the generation of plasma P and the movement of the rotating body 20. The space surrounding the irradiation position I enclosed by the housing 19 becomes the plasma generation space where plasma P is generated.

[0117] In this example, the port 23 is fixed by connecting its tip to the housing 19. Alternatively, the port 23 may be fixed to a cover or the like to prevent the plasma material 101 from flowing out.

[0118] In Figure 9B, the vacuum chamber 103 has a partition wall 40 that separates the port 23 from the focusing mirror 24 (not shown), and the port 23 is fixed by connecting its rear end to the partition wall 40. With the configurations in Figures 9A and B, a high-pressure space is more easily formed around the irradiation position I, and further improvement in the P×D value can be expected.

[0119] In the configuration shown in Figure 9B, the exhaust system may be located closer to the irradiation position I than the partition wall 40. The inside of port 23 is under relatively high pressure, and the mean free path of the gas is usually sufficiently smaller than the length of the internal space T of port 23. Therefore, it is presumed that the gas behaves like an intermediate flow inside port 23. Debris that collides with the gas and loses kinetic energy is thought to be discharged along the gas flow.

[0120] At this time, if the debris that has lost its kinetic energy is transported to the focusing mirror 24 side, the debris will adhere to the surface of the focusing mirror 24, causing a decrease in reflectivity, etc. Therefore, it is desirable for the gas to flow toward the irradiation position I. By providing an exhaust system, the gas pressure around the irradiation position I decreases, and if a gas inlet 27 is provided on the side of the port 23, it becomes easier to form a gas flow from the internal space T toward the irradiation position I. The effective exhaust velocity of the exhaust system may be adjusted as appropriate according to the configuration of the plasma generation mechanism 106 and the partition wall 40.

[0121] Port 23 may be fixed to the inner wall of the vacuum chamber 103. Specifically, in Figures 9A and 9B, a fixing part, for example, a rod shape, protrudes downward from an inner wall (not shown) located on the upper side of the paper, and the port 23 is fixed by connecting the conduit 25 of the port 23 to this fixing part.

[0122] This achieves the same effects as the configurations shown in Figures 9A and 9B. In addition, port 23 becomes less susceptible to the effects of thermal deformation of the plasma generation mechanism 106 and the vacuum chamber 103. That is, it prevents the inability to adequately transmit radiation R due to the position of port 23 shifting from its design position. To further suppress thermal deformation, a cooling mechanism may be provided in the vacuum chamber 103.

[0123] Port 23 may have an adjustment mechanism to adjust the position of the conduit 25. For example, the adjustment mechanism adjusts the position of port 23 in the Z direction in Figure 2. This makes it possible to maintain the radiation R transmission performance by correcting any unintended positional or morphological displacement of port 23 due to thermal deformation or the like.

[0124] The specific configuration of the adjustment mechanism is not limited. In particular, in the configuration in which the aforementioned port 23 is fixed to the inner wall of the vacuum chamber 103, it is possible to easily provide an adjustment mechanism by attaching it to the inner wall. Conversely, the irradiation position I of the energy beam EB may also be adjusted. This method is also useful when an adjustment mechanism cannot be provided.

[0125] [Port shape] Figure 10 is a schematic diagram showing examples of variations in port shape. Figure 10 shows a box-shaped port 43 viewed from approximately the negative side in the Y direction. Specifically, the conduit 44 of the port 43 has two opposing, roughly fan-shaped surfaces 45a and 45b, and two opposing, rectangular surfaces 46a and 46b.

[0126] Faces 45a and 45b have a shape obtained by removing sector B, which is part of circle B, from sector A, which is part of circle A, when considering circle A and circle B, which has a smaller radius than circle A but the same center. Furthermore, the central angles of sectors A and B are equal. Faces 45a and 45b are arranged opposite each other, parallel to the XY plane.

[0127] Both surfaces 46a and 46b are rectangles formed by the edges of surface 45a, the edges of surface 45b, and two edges parallel to the Z direction, and are arranged opposite each other and parallel to the Z direction. Surfaces 45a, 45b, 46a, and 46b form a cylindrical shape, and the space enclosed by these surfaces becomes the internal space T of port 43, where the ejection axis EA is located.

[0128] The area of ​​the aperture 47b downstream of port 43 is larger than the area of ​​the aperture 47a on the light-emitting side. Also, the cross-sectional area of ​​the most negative portion in the Y direction, as defined by the XZ plane, is approximately S, and the distance from the irradiation position I to that portion is X.

[0129] If there are spatial constraints when arranging port 43, such a shape may be adopted in accordance with the arrangement of other mechanisms. In addition, any port shape and arrangement may be adopted that has a cylindrical shape, through which radiation R passes, and where the area of ​​the downstream opening is larger than the area of ​​the emission-side opening, satisfying the conditional equation.

[0130] Furthermore, a foil trap for capturing debris may be placed in the internal space of the port 23 in this invention. For example, by arranging the foil along the radiation R emitted from the irradiation position I, it is possible to allow the radiation R to pass through the internal space T of the port 23 while further enhancing the removal of debris generated from the irradiation position I.

[0131] [margin] In the example shown in Figure 8, the minimum cross-sectional area of ​​the conduit 35 and the internal space T was defined as S, so S included the cross-sectional area of ​​the conduit 35 itself. This was done to allow a margin in S to avoid a situation where radiation R would not be sufficiently transmitted, taking into account the positional displacement of the port 23.

[0132] On the other hand, margins do not need to be considered. That is, even if the minimum value of the cross-sectional area of ​​only the internal space T is taken as S, equation (2) may still be satisfied for θ calculated by equation (1).

[0133] Furthermore, even if we consider the minimum value of the cross-sectional area of ​​only the internal space T as S, the condition 5°≦θ≦20° may still hold.

[0134] Furthermore, in the case of a port 23 having a frustoconical shape, if the design opening angle is θ', the conditional equation may be examined based on a margin of θ = θ' + α. In addition, a safety factor may be taken into consideration, such as multiplying a predetermined parameter by 150%.

[0135] [Types of plasma raw materials] The specific type of plasma raw material 101 is not limited. For example, not only completely liquid plasma raw material 101, but also plasma raw material 101 in which solid material in the process of melting is mixed in with the liquid may be used.

[0136] [Applications to other devices] In this example, we have described the application of this technology 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.

[0137] It is also possible to combine at least two of the feature elements of this technology described above. Furthermore, the various effects described above are merely examples and are not limiting, and other effects may also occur. [Explanation of Symbols]

[0138] EA...Emission axis EB... Energy beam I…Irradiation position P...Plasma R...Radiation T, T'...Inner space 19… cabinet 22…Light extraction unit Ports 23, 34, 43, 51… 24... Light-gathering mirror 25, 35, 44, 53…conduit 26a, 26b, 36a, 36b, 47a, 47b...Aperture 27...Gas inlet 28, 52...Flowmeter 40...Bulkhead 45a, 45b, 46a, 46b...surface 50…Injection Unit 54…Debris reduction tools 100...Light source device 101... Plasma raw materials 103... Vacuum Chamber 106…Plasma generation mechanism

Claims

1. A light source device that generates radiation by turning raw materials into plasma through energy injection, Chamber and, A raw material supply unit housed in the chamber and supplying the raw material to the energy irradiation position, An energy source that injects the energy at the energy irradiation position to generate plasma, A port having a conduit, arranged such that the radiation or energy passes through the internal space surrounded by the conduit, wherein in the arrangement, the opening closer to the energy irradiation position is designated as the light-emitting side opening, and the opening further away is designated as the downstream side opening, and the area of ​​the downstream side opening is larger than the area of ​​the light-emitting side opening, It comprises a gas introduction section configured to be closer to the energy irradiation position than the downstream opening, The minimum cross-sectional area of ​​the conduit and the internal space, measured by a plane perpendicular to the optical axis of the radiation or the optical axis of the energy, is S (mm²). ２ )year, Let X (mm) be the distance between the energy irradiation position and the cross-section with the minimum cross-sectional area. [Math 1] year, When the distance between the energy irradiation position and the light-emitting aperture is d (mm), [Math 2] That is Light source device.

2. A light source device according to claim 1, The port is arranged such that the radiation passes through the internal space surrounded by the conduit. The aforementioned S (mm ２ ) is the minimum value of the cross-sectional area of ​​the conduit and the internal space by a plane perpendicular to the optical axis of the radiation. Light source device.

3. A light source device according to claim 1 or 2, The port is arranged such that the energy passes through the internal space surrounded by the conduit. The aforementioned S (mm ２ ) is the minimum value of the cross-sectional area of ​​the conduit and the internal space by a plane perpendicular to the optical axis of the energy. Light source device.

4. A light source device according to claim 3, further, The system includes a debris reduction device for capturing debris generated at the energy irradiation location. Light source device.

5. A light source device according to claim 1 or 2, 5° ≤ θ ≤ 20° Light source device.

6. A light source device according to claim 1 or 2, The conduit has the shape of a truncated cone. Light source device.

7. A light source device according to claim 1 or 2, The conduit has two opposing, substantially fan-shaped surfaces and two opposing, rectangular surfaces. Light source device.

8. A light source device according to claim 1 or 2, The gas introduction section is an opening formed in the conduit. Light source device.

9. A light source device according to claim 1 or 2, The gas introduction section is configured in the space between the energy irradiation position and the light-emitting side opening. Light source device.

10. A light source device according to claim 1 or 2, The raw material supply unit has a housing that surrounds the energy irradiation position and forms a plasma generation space. Light source device.

11. A light source device according to claim 10, The port is fixed to the housing. Light source device.

12. A light source device according to claim 1 or 2, further, The system comprises a focusing mirror positioned on the optical axis at a location further from the energy irradiation position than the port, The chamber has a partition wall separating the port and the focusing mirror. The port is fixed to the partition wall. Light source device.

13. A light source device according to claim 1 or 2, The minimum cross-sectional area of ​​the internal space only, as defined by the plane, is S (mm²). ２ Even if you do this, The condition 5° ≤ θ ≤ 20° holds true. Light source device.

14. A light source device according to claim 1 or 2, The port has an adjustment mechanism for adjusting the position of the conduit. Light source device.

15. A light source device according to claim 1 or 2, further, The system includes a measuring unit for measuring the amount of gas introduced by the aforementioned gas introduction unit. Light source device.

16. A light source device that generates radiation by turning raw materials into plasma through energy injection, Chamber and, A raw material supply unit housed in the chamber and supplying the raw material to the energy irradiation position, An energy source that injects the energy at the energy irradiation position to generate plasma, A port having a conduit, arranged such that the radiation or energy passes through the internal space surrounded by the conduit, wherein in the arrangement, the opening closer to the energy irradiation position is designated as the light-emitting side opening, and the opening further away is designated as the downstream side opening, and the area of ​​the downstream side opening is larger than the area of ​​the light-emitting side opening, A gas introduction section is configured at a position closer to the energy irradiation position than the downstream opening. In a light source device comprising, The minimum cross-sectional area of ​​the conduit and the internal space, measured by a plane perpendicular to the optical axis of the radiation or the optical axis of the energy, is S (mm²). ２ )year, Let X (mm) be the distance between the energy irradiation position and the cross-section with the minimum cross-sectional area. [Math 1] year, When the distance between the energy irradiation position and the light-emitting aperture is d (mm), [Math 2] That is Method for extracting radiation.

Images