Light source device and pressure operation mechanism

Abstract

The purpose of the present invention is to provide a light source device and a pressure operation mechanism that make it possible to operate gas pressure at a light emission point with a simple configuration.　A light source device according to an aspect of the present invention generates radiation by converting a starting material into plasma by energy injection, and comprises a chamber, a starting material supply part, an energy source, and a pressure operation mechanism. The pressure operation mechanism comprises a radiation emission part and a gas introduction part. The radiation emission part is connected to a housing forming a plasma generation space, has a cylindrical shape having a forward end protruding into the plasma generation space, has an opening communicating with the plasma generation space and facing an energy injection position at the forward end, and forms a radiation emission space the inner diameter of which increases from the opening with distance from the energy injection position. The gas introduction part introduces gas into the plasma generation space and / or the radiation emission space, and a gas ejection direction faces a wall surface facing a wall surface to which the gas introduction part is connected.

Description

Light source device and pressure operating mechanism

[0001] The present invention relates to a light source device and a pressure operating mechanism that convert a raw material into plasma by energy supply and generate radiation.

[0002] An EUV (Extreme Ultra Violet) light source device that generates EUV generates high-temperature plasma by supplying and exciting a plasma raw material, which is a molten metal such as tin, with powerful energy, and extracts EUV from the high-temperature plasma. A device that uses a laser for powerful energy is called an LPP (Laser Produced Plasma) light source device, and a device that uses discharge is called a DPP (Discharge Produced Plasma) light source device (see, for example, Patent Document 1). Among DPP light source devices, a method that additionally uses a laser in the process of obtaining plasma is called LDP (Laser Assisted Discharge Produced Plasma) (see, for example, Patent Document 2).

[0003] An LPP light source device is known to generate plasma by condensing a laser on droplets of a plasma raw material. In contrast, in recent years, a method has been developed in which a liquid plasma raw material is applied to a rotating body and the plasma raw material is supplied to the laser irradiation region (see, for example, Patent Document 3). This method does not require the supply of the liquid plasma raw material as droplets. Therefore, a relatively simple configuration is possible compared to a method such as condensing a laser on droplets, and high-intensity radiation can be obtained.

[0004] Japanese Patent Application Laid-Open No. 2008-108945, Japanese Patent Application Laid-Open No. 2012-209182, Japanese Patent Application Laid-Open No. 2014-216286

[0005] However, in any light source device, it is necessary to inject enormous amounts of energy to generate the high-temperature plasma that produces EUV, and plasma raw materials are scattered from the plasma generated by that energy. These scattered materials are called debris. This debris is released in various forms and damages various components placed inside the chamber. In particular, the focusing mirror that focuses the EUV emitted from the plasma and transmits it to the tool is affected by the debris, resulting in sputtering, where the reflective surface is abraded by the debris, deposition, where the debris accumulates on the reflective surface, and implantation, where the debris is driven deep into the reflective surface.

[0006] In this context, a high light intensity is generally required for the light source. Naturally, a high light intensity is also required for EUV light sources. In this case, if the input energy is large, the light intensity will increase accordingly, but there is a limit to the energy that can be injected locally. Therefore, it is necessary to use the emission efficiently, and this requires increasing the angle at which the light is extracted (hereinafter referred to as the light extraction angle).

[0007] However, widening the light extraction angle increases the amount of debris scattered within that angle. One method to remove this debris is to increase the pressure of a gas that is relatively transparent to EUV directly above the energy incidence point, which is the EUV emission point. This gas reduces or stops the velocity of incoming debris, thereby reducing the amount of debris that reaches the downstream optical system. However, increasing the light extraction angle increases the gas conductance. When the gas conductance increases, the gas is more likely to dissipate from the optical path, making it difficult to form a localized high-pressure space.

[0008] Furthermore, the gas pressure at the EUV emission point is extremely important for users of EUV light sources because it affects the energy input to the EUV emission point, the plasma shape at the EUV emission point, the shape of the EUV light spot, and the direction of EUV radiation. Therefore, it is desirable for EUV light sources to not only create the high-pressure space mentioned above, but also to be able to manipulate the gas pressure at the EUV emission point according to the intended use of EUV.

[0009] Specifically, if the gas pressure at the EUV emission point is high, the bright spot becomes smaller, which is suitable for applications such as high-resolution imaging. However, if the input energy is not high enough, the plasma may not light up, or it may fluctuate due to the gas pressure, potentially causing flicker. On the other hand, if the gas pressure at the EUV emission point is low, the plasma becomes larger, which is unsuitable for applications such as high-resolution imaging, but the plasma lights up easily, providing stability.

[0010] Thus, to enable application to a wide range of uses, it is desirable to be able to manipulate the gas pressure at the EUV emission point. One method of pressure manipulation is adjusting the gas introduction rate. However, relying solely on increasing or decreasing the gas introduction rate makes it difficult to optimize the gas distribution along the entire optical path, including the plasma generation region. In particular, the vicinity of the EUV emission point is a concentration of various elements and components, making it difficult to add gas inlets. Therefore, there is a need for a mechanism that manipulates gas pressure using a simpler method or structure that does not rely solely on adjusting gas inlets or introduction rates.

[0011] In view of the above circumstances, the object of the present invention is to provide a light source device and a pressure control mechanism that can control the gas pressure at the light source point with a simple configuration.

[0012] To achieve the above objective, a light source device according to one embodiment of the present invention is a light source device that generates radiation by plasmaizing a raw material by injecting energy, and comprises a chamber, a raw material supply unit, an energy source, and a pressure operation mechanism. The raw material supply unit has a housing that is housed in the chamber, supplies the raw material to the energy injection position, and forms a plasma generation space surrounding the energy injection position. The energy source injects energy to the energy injection position to generate plasma in the plasma generation space. The pressure operation mechanism comprises a radiation emission unit and a gas introduction unit. The radiation emission unit is connected to the housing, is cylindrical with its tip protruding into the plasma generation space, and has an opening at its tip that communicates with the plasma generation space and faces the energy injection position, forming a radiation emission space from the opening whose inner diameter increases as it moves away from the energy injection position. The gas introduction unit is a gas introduction unit that introduces gas into at least one of the plasma generation space and the radiation emission space, wherein the gas ejection direction faces the wall surface opposite to the wall surface to which the gas introduction unit is connected.

[0013] With this configuration, by introducing gas from the gas introduction section into at least one of the plasma generation space and the radiation emission space, it becomes possible to control the gas pressure near the energy injection point, shield the debris, and emit radiation through the radiation emission space.

[0014] The radiation emitting portion has an inner circumferential surface facing the radiation emitting space, an outer circumferential surface opposite to the inner circumferential surface, and an end surface at the tip connecting the inner circumferential surface and the outer circumferential surface, and the angle between the inner circumferential surface and the end surface may be 10° or more and 90° or less.

[0015] The angle formed above may be between 10° and 60°.

[0016] The radiation emitting portion has an inner circumferential surface facing the radiation emitting space, an outer circumferential surface opposite to the inner circumferential surface, and an end surface at the tip connecting the inner circumferential surface and the outer circumferential surface, and the angle between the inner circumferential surface and the end surface may be 90° or more and 170° or less.

[0017] The area of ​​the aforementioned opening is 625 mm². ２ The following is also acceptable.

[0018] The gas introduction unit may include a first gas inlet located in the plasma generation space, a second gas inlet located in the radiation emission space, and a flow control unit that controls the gas flow rate from the first gas inlet and the gas flow rate from the second gas inlet.

[0019] The energy source may inject energy into the energy injection position by laser irradiation.

[0020] To achieve the above objective, a pressure operation mechanism according to one embodiment of the present invention is a pressure operation mechanism provided in a light source device that generates radiation by plasmaizing a raw material by injecting energy, and comprises a radiation emission section and a gas introduction section. The radiation emission section is connected to a housing that forms a plasma generation space surrounding an energy injection position where the energy is injected into the raw material, and is cylindrical with its tip protruding into the plasma generation space, and has an opening at its tip that communicates with the plasma generation space and faces the energy injection position, forming a radiation emission space in which the inner diameter increases from the opening as it moves away from the energy injection position. The gas introduction section is a gas introduction section that introduces gas into at least one of the plasma generation space and the radiation emission space, and the direction of gas ejection faces a wall surface facing the wall surface to which the gas introduction section is connected.

[0021] According to the present invention, it is possible to provide a light source device and a pressure control mechanism that can control the gas pressure at the light-emitting point with a simple configuration.

[0022] This is a schematic diagram of a light source device according to an embodiment of the present invention. This is a schematic diagram of the raw material supply unit of the light source device. This is a schematic diagram of the raw material supply unit and pressure operation mechanism of the light source device. This is a schematic diagram showing various shapes of the tip of the radiation emission unit of the pressure operation mechanism. This is a simulation model of the effect of the tip shape of the radiation emission unit on the pressure in the radiation emission space. This is an enlarged view of the simulation model shown in Figure 5. This is a graph showing the results of the above simulation. This is a graph showing the results of the above simulation. This is a graph showing the results of the above simulation.

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

[0024] [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 (Laser Produced Plasma) type light source device. That is, as shown in Figure 1, the light source device 100 is a device that excites the liquid plasma material 101 by irradiating it with an energy beam EB to generate plasma P, and extracts the radiation R emitted from the plasma P to use as a light source. The radiation R is EUV (Extreme Ultraviolet) light, X-rays, or other electromagnetic waves.

[0025] The liquid plasma raw material 101 is a molten metal or alloy, such as 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. When EUV light is emitted as radiation R, molten Sn or Li is used as the liquid plasma raw material 101. When X-rays are emitted as radiation R, molten Ga, Ga alloys, Sn compounds, etc., are used as the liquid plasma raw material 101.

[0026] 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 direction will be described as the left-right direction within the horizontal direction (the positive side of the X axis is the right side, and the negative side is the left side), the Y direction as the front-back direction within the horizontal direction (the positive side of the Y axis is the front side, and the negative side is the rear side), and the Z direction as the vertical direction (the positive side of the Z axis is the upper side, and the negative side is the lower side). Of course, the application of this technology is not limited to the orientation in which the light source device 100 is used.

[0027] As shown in Figure 1, the light source device 100 includes an outer peripheral member 102, a vacuum chamber 103, an energy beam injection chamber 104, a radiation emission chamber 105, a raw material supply unit 106, a pressure operation mechanism 107, a control unit 108, and a beam source 109.

[0028] In the example shown in Figure 1, the outer peripheral member 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.

[0029] As shown in Figure 1, a beam source 109 that emits an energy beam EB is installed outside the outer peripheral member 102. The beam source 109 is positioned so that the energy beam EB is incident on the interior of the outer peripheral member 102 along the incident axis IA. An electron beam or laser light can be used as the energy beam EB.

[0030] The light source device 100 is provided with a chamber section C 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.

[0031] The injection chamber 104 is configured to be located on the injection axis IA of the energy beam EB, and the output chamber 105 is configured to be located on the output axis EA of the radiation R. A collector (focusing mirror) 113 that guides the radiation R is placed inside the output chamber 105. A raw material supply unit 106 that supplies liquid plasma raw material 101 to the injection position of the energy beam EB is located inside the vacuum chamber 103.

[0032] A user device, such as a mask inspection device, is connected to the end of the ejection chamber 105 opposite the raw material supply section 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. The gas inside the application chamber 110 may also be exhausted by an exhaust means not shown. A filter membrane 111 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.

[0033] The chamber body 112 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 112.

[0034] 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.

[0035] The raw material supply unit 106 is a mechanism that supplies liquid plasma raw material 101 to the incidence position of the energy beam EB. As shown in Figure 1, the raw material supply unit 106 includes a rotating body 120, to which the energy beam EB is incident. The rotating body 120 is positioned within the vacuum chamber 103 such that the injection position I, where the energy beam EB is irradiated and energy is injected, is located at the intersection of the incidence axis IA and the output axis EA. Details of the raw material supply unit 106 will be described later.

[0036] The pressure control mechanism 107 controls the gas pressure near the injection position I. As shown in Figure 1, the pressure control mechanism 7 is housed in the vacuum chamber 103 and connected to the raw material supply unit 106. Details of the pressure control mechanism 107 will be described later.

[0037] The control unit 108 controls the operation of each component of the light source device 100. For example, the control unit 108 controls the operation of the pressure operating mechanism 107, the beam source 109, and the exhaust pump 117. The control unit 108 has hardware circuits necessary for a computer, such as a CPU and memory (RAM, ROM). Various processes are executed by the CPU loading a control program stored in memory into the RAM and executing it. A device such as a PLD (Programmable Logic Device) may be used as the control unit 108. In Figure 1, the control unit 108 is schematically shown as a functional block, but the position and other aspects of the control unit 108 can be designed arbitrarily.

[0038] Furthermore, as shown in Figure 1, in this embodiment, a radiation diagnostic unit 119 is connected to the chamber body 112. The radiation diagnostic unit 119 is positioned where radiation R, which is emitted in a direction different from the radiation emission axis EA, is incident, and measures the state of radiation R emitted from the plasma P.

[0039] [Configuration of the raw material supply unit] As described above, the raw material supply unit 106 is a mechanism that supplies liquid plasma raw material 101 to the incident position of the energy beam EB. Figure 2 is a schematic diagram of the raw material supply unit 106. As shown in Figures 1 and 2, the raw material supply unit 106 comprises a rotating body 120, a rotary drive source 131, a shaft portion 132 and a storage tank 133, a housing 134 and a heating unit 135.

[0040] The rotary drive source 131 generates rotational power for the rotating body 120. The rotary drive source 131 is, for example, a motor. The rotary drive source 131 may be located outside the vacuum chamber 103 or inside the vacuum chamber 103. The shaft 132 connects the rotary drive source 131 and the rotating body 120 and transmits the rotational power generated in the rotary drive source 131 to the rotating body 120. The shaft 132 is rotatably supported by a mechanical seal 136. The storage tank 133 is located vertically below the rotating body 120 and stores the liquid plasma material 101.

[0041] The rotating body 120 is placed inside the vacuum chamber 103 and connected to the shaft portion 132. The rotating body 120 rotates due to the rotation of the shaft portion 132, as shown by arrow S1 in Figure 2. Hereafter, the axis of rotation of the rotating body 120 and the shaft portion 132 will be referred to as the rotation axis M.

[0042] As shown in Figure 2, the rotating body 120 has a disc shape. Hereinafter, the surface of the rotating body 120 opposite to the shaft portion 132 will be referred to as the rotating surface 120a. The rotation axis M is, for example, parallel to the horizontal direction (X-Y direction), and the rotating surface 120a is positioned parallel to the vertical direction. A portion of the rotating surface 120a is immersed in the liquid plasma material 101 stored in the storage tank 133, and the liquid plasma material 101 adheres to it as it rotates. The liquid plasma material 101 adhering to the rotating surface 120a is transported to the injection position I as shown by arrow S2 in the figure as the rotating body 120 rotates, and is plasma-generated by the energy beam EB irradiated onto the injection position I.

[0043] The housing 134 houses the rotating body 120 to prevent debris from scattering. Further, the housing 134 forms a plasma generation space 137 which is a space where plasma is generated, surrounding the periphery of the injection position I. The liquid plasma raw material 101 is stored in the vertically lower part of the housing 134, and the vertically lower part of the housing 134 constitutes the storage tank 133.

[0044] The heating unit 135 heats the liquid plasma raw material 101. The heating unit 135 is disposed on the outer periphery of the vertically lower part of the housing 134, that is, the storage layer 133, and heats the liquid plasma raw material 101 through the housing 134. Further, the heating unit 135 may be disposed in the storage tank 133 to directly heat the liquid plasma raw material 101.

[0045] As shown in FIG. 1, a film thickness adjustment mechanism 138 may be disposed around the rotating body 120 with a predetermined gap so as to sandwich the rotating body 120, and the film thickness of the liquid plasma raw material 101 is adjusted by scraping off the liquid plasma raw material 101 that has not flowed into the gap. The film thickness adjustment mechanism 138 is provided on the upstream side of the injection position I in the rotation direction of the rotating body 120 and defines the film thickness of the liquid plasma raw material 101 at the injection position I.

[0046] The configuration of the raw material supply unit 106 is not limited to that shown here, and any configuration may be used as long as it supplies the liquid plasma raw material 101 to the injection position I and has a housing that surrounds the periphery of the injection position I and forms the plasma generation space 137.

[0047] [Regarding the configuration of the pressure operation mechanism] The pressure operation mechanism 107 operates the gas pressure in the vicinity of the injection position I as described above. FIG. 3 is a schematic diagram of the raw material supply unit 106 and the pressure operation mechanism 107. As shown in the figure, the pressure operation mechanism 107 includes a radiation emission unit 141, a gas introduction unit 142, and a flow rate control unit 143.

[0048] The radiation emission unit 141 allows radiation R to pass through while shielding the debris. As shown in Figure 3, the radiation emission unit 141 is connected to the housing 134, and its tip 141a protrudes into the plasma generation space 137. The radiation emission unit 141 has a first opening 151, a second opening 152, and a side wall portion 153. The first opening 151 is the opening on the tip 141a side and communicates with the plasma generation space 137. The first opening 151 also faces the injection position I. The second opening 152 is the opening on the opposite side from the tip 141a and communicates with the vacuum chamber 103.

[0049] The side wall portion 153 is provided between the first opening 151 and the second opening 152, and separates the internal space from the external space, except for the first opening 151 and the second opening 152. Hereinafter, this internal space will be referred to as the radiation emission space 154. As shown in Figure 3, the side wall portion 153 has a shape in which the inner diameter D of the radiation emission space 154 gradually increases from the first opening 151 to the second opening 152, that is, the inner diameter gradually increases as it moves away from the injection position I. Specifically, the side wall portion 153 can be conical. The side wall portion 153 may also be other conical shapes such as a square pyramidal shape or a triangular pyramidal shape, and may have a shape other than a conical shape in which the inner diameter gradually increases as it moves away from the injection position I. The side wall portion 153 may be provided with a through hole for the energy beam EB to pass through, but since this through hole is extremely small compared to the first opening 151 and the second opening 152, it has almost no effect.

[0050] The radiation emission section 141 only needs to have its first opening 151 facing the injection position I. As shown in Figure 3, if the normal of the rotational surface 120a at the injection position I is taken as the normal H, the radiation emission section 141 may have its central axis coincide with the normal H, or it may be inclined from the normal H. Since the radiation R is emitted by diffusion from the injection position I, it can pass through the radiation emission space 154 if the first opening 151 faces the injection position I. As for the specific configuration of the radiation emission section 141, the preferred value of the distance K between the tip 141a and the injection position I depends on the opening angle of the pressure operation mechanism 107. The distance K is preferably 100 mm or less. This makes it easier to secure a sufficient opening angle, and is even more preferably 50 mm or less. In practice, it is 10 mm or less. Also, the area of ​​the first opening 151 is 625 mm². ２The following are preferred.

[0051] The gas introduction unit 142 introduces gas into at least one of the plasma generation space 137 and the radiation emission space 154. Specifically, as shown in Figure 3, the gas introduction unit 142 has a first gas inlet 155 and a second gas inlet 156. The first gas inlet 155 is located in the plasma generation space 137 and is connected to a gas source (not shown) via a first pipe 157. The second gas inlet 156 is located in the radiation emission space 154 and is connected to a gas source (not shown) via a second pipe 158. The gas introduced by the gas introduction unit 142 can be any gas that can penetrate radiation R, such as argon or helium. The gases introduced from the first gas inlet 155 and the second gas inlet 156 may be the same type of gas or different types of gas.

[0052] As shown in Figure 3, among the walls of the housing 134, the wall to which the first gas inlet 155 is connected is designated as the first wall surface 134a, and the wall surface opposite to the first wall surface 134a is designated as the second wall surface 134b. The first gas inlet 155 is preferably one in which the gas ejection direction faces the second wall surface 134b. In addition, among the side walls 153 of the radiation emission section 141, the wall to which the second gas inlet 156 is connected is designated as the third wall surface 153a, and the wall surface opposite to the third wall surface 153a is designated as the fourth wall surface 153b. The second gas inlet 156 is preferably one in which the gas ejection direction faces the fourth wall surface 153b. Note that both the first gas inlet 155 and the second gas inlet 156 may be provided, or only one of them may be provided.

[0053] The flow rate control unit 143 controls the flow rate of gas discharged from the first gas inlet 155 and the second gas inlet 156. The flow rate control unit 143 can control the flow rate by adjusting the opening of valves provided in the first pipe 157 and the second pipe 158, respectively. The flow rate control unit 143 is connected to the control unit 108 (see Figure 1) and controls the flow rate in response to instructions from the control unit 108. Alternatively, the user may control the flow rate instead of the flow rate control unit 143.

[0054] The light source device 100 has the configuration described above. When liquid plasma raw material 101 is supplied to the injection position I (see Figure 2) by the raw material supply unit 106, and an energy beam EB is irradiated to the injection position I from the beam source 109, the liquid plasma raw material 101 is converted into plasma at the injection position I, and plasma P is generated. Radiation R such as EUV is emitted from the plasma P, and the radiation R is emitted by passing through the radiation emission space 154. Debris is scattered from the liquid plasma raw material 101 as it is converted into plasma, but the debris is shielded by the radiation emission space 154 which is adjusted to high pressure, preventing it from adhering to optical systems such as the collector 113 (see Figure 1).

[0055] [Regarding the tip shape of the radiation emission section] The shape of the tip 141a of the radiation emission section 141 will be described below. Figure 4 is a schematic diagram showing various shapes of the tip 141a. In Figures 4(a) to (c), the side of the side wall 153 facing the radiation emission space 154 is defined as the inner circumferential surface 153c, and the side opposite to the inner circumferential surface 153c is defined as the outer circumferential surface 153d. The surface connecting the inner circumferential surface 153c and the outer circumferential surface 153d at the tip 141a is defined as the end surface 153e. A part of the inner circumferential surface 153c constitutes the third wall surface 153a and the fourth wall surface 153b described above (see Figure 3). As shown in Figures 4(a) to (c), the angle between the inner circumferential surface 153c and the end surface 153e is defined as angle θ, and the diameter of the first opening 151 is defined as diameter A.

[0056] As shown in Figures 4(a) and (b), the angle θ can be between 10° and 90°, and can be an acute angle. An angle θ of 10° to 60° is more preferable. Also, as shown in Figure 4(c), the angle θ can be between 90° and 170°, and can be an obtuse angle. As shown in Figures 4(a) to (c), even if the diameter A is the same, the pressure in the radiation emission space 154 can be controlled by adjusting the angle θ.

[0057] The following describes the results of a simulation of the effect of angle θ on the pressure in the radiation emission space 154. Figures 5 and 6 show the simulation model, and Figures 6(a) to (c) are enlarged views of Figure 5. As shown in Figure 5, a conical radiation emission space 154 is connected to the center of the end of a Φ400 mm × 400 mm space, and a plasma generation space 137 of Φ60 mm × 20 mm is connected to the end of the radiation emission space 154. In this specification, Φ always refers to the diameter. The radiation emission space 154 protrudes into the plasma generation space 137, and its tip shape is one of three types shown in Figures 6(a) to (c). In Figure 6(a), the angle θ is 30°, and this shape is referred to as "shape a". In Figure 6(b), the angle θ is 65°, and this shape is referred to as "shape b". In Figure 6(c), the angle θ is 150°, and this shape is referred to as "shape c". The distance K (see Figure 3) was set to 10 mm in all cases.

[0058] The first gas inlet 155 was connected to the plasma generation space 137 and had a diameter of Φ3 mm. The second gas inlet 156 was connected to the vicinity of the tip 141a of the radiation emission space 154 and had a diameter of Φ3 mm. In each shape shown in Figures 6(a) to (c), gas was introduced from the first gas inlet 155 and the second gas inlet 156 at the flow rates shown in Table 1 below, and the pressure distribution along line N (see Figure 5) was calculated. Line N is a line that extends in the X direction with the injection position I as the origin.

[0059]

[0060] Figures 7 to 9 show the calculated pressure distribution. As shown in Figure 7, when 1000 sccm of gas was introduced from the first gas inlet 155 and no gas was introduced from the second gas inlet 156, the pressure was as follows: shape a ≥ shape b > shape c. In particular, shapes a and b were able to achieve high pressures exceeding 180 Pa near the light emission point (injection position I).

[0061] Furthermore, as shown in Figure 8, when gas is not introduced from the first gas inlet 155 and 1000 sccm of gas is introduced from the second gas inlet 156, the pressure near the light-emitting point becomes 40 Pa in all shapes, indicating that the pressure at the light-emitting point can be controlled by the tip shape of the radiation emission section 141. In addition, focusing on the results for shapes a and b from these results, it was found that these shapes allow for the largest fluctuation range of pressure at the light-emitting point.

[0062] Figure 9 shows the pressure distribution for shape a, which had the largest amplitude of fluctuation. It was found that when gas was introduced only from the first gas inlet 155, the pressure at the emission point increased, and when the amount of gas introduced was halved, the pressure at the emission point was also halved accordingly. Furthermore, when gas was introduced from the second gas inlet 156, the pressure at the emission point did not rise much, and it was found that the region with a relatively high pressure of about 70 Pa could be expanded not only to the tip 141a of the radiation emission space 154 but also to the interior. This showed that a high-pressure space could be maintained to some extent on the tip 141a side of the radiation emission space 154.

[0063] As described above, the radiation emission unit 141 can control the pressure at the light emission point by the shape of its tip 141a, as shown in Figures 4(a) to (c). Furthermore, the pressure distribution near the light emission point and in the radiation emission space 154 can be controlled by the flow rate of the gas introduced from the first gas inlet 155 and the second gas inlet 156, respectively.

[0064] [Modification] In the above description, the light source device 100 is described as an LPP (Laser Assisted Discharge Produced Plasma) type light source device, but it is not limited to this, and may be a DPP (Discharge Produced Plasma) type or LDP (Laser Assisted Discharge Produced Plasma) type light source device. In the DPP and LDP types, energy is injected into the injection position by discharge to turn the liquid plasma material into plasma. In these types as well, by providing the above-described radiation emission unit 141 near the injection position, it is possible to shield the debris generated during plasma formation.

[0065] [About this disclosure] It is possible to combine at least two of the feature features of the present technology described above. That is, the various feature features described in each embodiment may be combined arbitrarily without distinction between embodiments. Furthermore, the various effects described above are merely examples and are not limiting, and other effects may also be exhibited.

[0066] 100...Light source device 141...Radiation emission unit 142...Gas introduction unit 143...Flow rate control unit 151...First opening 152...Second opening 153...Side wall 153c...Inner circumferential surface 153d...Outer circumferential surface 153e...End face 154...Radiation emission space 155...First gas inlet 156...Second gas inlet

Claims

1. A light source device for generating radiation by plasmaizing a raw material by injecting energy, comprising: a chamber; a raw material supply unit housed in the chamber and having a housing that supplies the raw material to an energy injection position and forms a plasma generation space surrounding the energy injection position; an energy source for injecting energy to the energy injection position to generate plasma in the plasma generation space; and a pressure operation mechanism comprising a radiation emission unit and a gas introduction unit, wherein the radiation emission unit is connected to the housing, is cylindrical with its tip protruding into the plasma generation space, has an opening at its tip that communicates with the plasma generation space and faces the energy injection position, and forms a radiation emission space in which the inner diameter increases from the opening as it moves away from the energy injection position; and the gas introduction unit is a gas introduction unit for introducing gas into at least one of the plasma generation space and the radiation emission space, wherein the direction of gas ejection faces the wall surface facing the wall surface to which the gas introduction unit is connected.

2. A light source device according to claim 1, wherein the radiation emitting portion has an inner circumferential surface facing the radiation emitting space, an outer circumferential surface opposite to the inner circumferential surface, and an end surface at the tip connecting the inner circumferential surface and the outer circumferential surface, and the angle between the inner circumferential surface and the end surface is 10° or more and 90° or less.

3. A light source device according to claim 2, wherein the angle formed is 10° or more and 60° or less.

4. A light source device according to claim 1, wherein the radiation emitting portion has an inner circumferential surface facing the radiation emitting space, an outer circumferential surface opposite to the inner circumferential surface, and an end surface at the tip connecting the inner circumferential surface and the outer circumferential surface, and the angle between the inner circumferential surface and the end surface is 90° or more and 170° or less.

5. The light source device according to claim 1, wherein the area of ​​the aperture is 625 mm². ２ The following is the light source device.

6. A light source device according to claim 1, wherein the gas introduction unit comprises a first gas inlet located in the plasma generation space, a second gas inlet located in the radiation emission space, and a flow rate control unit that controls the gas flow rate from the first gas inlet and the gas flow rate from the second gas inlet.

7. A light source device according to claim 1, wherein the energy source is a light source device that injects energy to the energy injection position by laser irradiation.

8. A pressure operating mechanism for a light source device that generates radiation by plasmaizing a raw material by injecting energy, comprising: a radiation emission section connected to a housing that forms a plasma generation space surrounding an energy injection position where the energy is injected into the raw material, having a cylindrical tip protruding into the plasma generation space, the tip having an opening that communicates with the plasma generation space and faces the energy injection position, and forming a radiation emission space in which the inner diameter increases from the opening as it moves away from the energy injection position; and a gas introduction section for introducing gas into at least one of the plasma generation space and the radiation emission space, wherein the direction of gas ejection of the gas introduction section faces a wall surface facing the wall surface to which the gas introduction section is connected.

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